GN/ New insight into the possible origins of life
Genetics biweekly vol.24, 9th March — 23d March
TL;DR
- Researchers have for the first time been able to create an RNA molecule that replicates, diversifies and develops complexity, following Darwinian evolution. This has provided empirical evidence that simple biological molecules can lead to the emergence of complex lifelike systems.
- Scientists have developed a novel method of delivering drugs into human cells using large biological molecules, by first encasing them in a protein-based microdroplet. This discovery promises to be faster, safer, more effective, and better suited for gene therapy, cancer treatment, and vaccine delivery.
- Animal and cell studies show that as retinal cells die in degenerative eye diseases, they make other cells hyperactive, creating noise that further obscures vision. Tests to prove this in humans are hard to conduct, however. Antabuse, an approved drug used to wean people off alcohol, should tamp down this hyperactivity and conclusively show whether hyperactivity plays a role in humans, potentially driving work to find better drugs to help those with progressive vision loss.
- Parkinson’s disease is a neurodegenerative disorder characterized by the destruction of a specific population of neurons: the dopaminergic neurons. A team has investigated the destruction of these dopaminergic neurons using the fruit fly as study model. The scientists identified a key protein in flies, and also in mice, which plays a protective role against this disease and could be a new therapeutic target.
- An inhalable ‘aerogel’ loaded with DNA that encodes for the SARS-CoV-2 spike protein successfully induces an immune response against COVID-19 in the lungs of mice, according to new research. The team said its aerogel could be used to create an inhalable vaccine that blocks SARS-CoV-2 transmission by preventing the virus from establishing an infection in the lungs.
- The DNA of a vulnerable species, the iconic Arabian Oryx, has been decoded. An international team undertook this project to help ensure the survival of the species, by using the genetic data to inform breeding programs.
- The p53 protein protects our cells from cancer and is an interesting target for cancer treatments. The problem is, however, that it breaks down rapidly in the cell. Researchers have now found an unusual way of stabilizing the protein and making it more potent. By adding a spider silk protein to p53, they show that it is possible to create a protein that is more stable and capable of killing cancer cells.
- In pursuit of better ways to test new therapies and further explore the impacts of the unique genetics associated with Down syndrome, researchers have genetically engineered and characterized what is believed to be the first rat model of Down syndrome.
- Researchers applied sophisticated genetic strategies in laboratory fruit flies to determine the functional consequences of de novo variants identified in the Simons Simplex Collection (SSC), which includes approximately 2,600 families affected by autism spectrum disorder. Surprisingly, their work also allowed them to uncover a new form of rare disease due to a gene called GLRA2.
- In what they call surprise findings, scientists report that — unlike fruit flies — mosquitoes’ odor sensing nerve cells shut down when those cells are forced to produce odor-related proteins, or receptors, on the surface of the cell. This ‘expression’ process apparently makes the bugs able to ignore common insect repellents.
- And more!
Overview
Genetic technology is defined as the term which includes a range of activities concerned with the understanding of gene expression, advantages of natural genetic variation, modifying genes and transferring genes to new hosts. Genes are found in all living organisms and are transferred from one generation to the next. Gene technology encompasses several techniques including marker-assisted breeding, RNAi and genetic modification. Only some gene technologies produce genetically modified organisms.
Modern genetic technologies like genome editing would not be possible without all the previous generations of genetic technologies that have enabled scientists to discover what genes are, what they do and how DNA can be modified to add, remove or replace genes. You can find major genetic technologies development milestones via the link.
Gene Technology Market
- The valuation of the genetic engineering market is projected to escalate to USD 6.90 MN by the end of 2027.
- Global Genetic Engineering Market is projected to grow at 12.48% CAGR during the assessment period (2017–2027).
- North America holds the largest share in the global genetic engineering market, followed by Europe and the Asia Pacific, respectively.
- Another research provider, MarketsandMarkets, forecasts the genome editing, genome engineering market to grow from USD 3.19 billion in 2017 to USD 6.28 billion by 2022, at a compounded annual growth rate (CAGR) of 14.5% during the forecast period. The key factors propelling market growth are rising government funding and growth in the number of genomics projects, high prevalence of infectious diseases (like COVID-19) and cancer, technological advancements, increasing production of genetically modified (GM) crops, and growing application areas of genomics.
Latest News & Research
Evolutionary transition from a single RNA replicator to a multiple replicator network
by Mizuuchi, R., Furubayashi, T. & Ichihashi, N. in Nature Communications
Researchers at the University of Tokyo have for the first time been able to create an RNA molecule that replicates, diversifies and develops complexity, following Darwinian evolution. This has provided the first empirical evidence that simple biological molecules can lead to the emergence of complex lifelike systems.
Life has many big questions, not least being where did we come from? Maybe you’ve seen the T-shirts with pictures going from ape to human (to tired office worker). But how about from simple molecule to complex cell to ape? For several decades, one hypothesis has been that RNA molecules (which are vital for cell functions) existed on primitive Earth, possibly with proteins and other biological molecules. Then around 4 billion years ago, they started to self-replicate and develop from a simple single molecule into diverse complex molecules. This step-by-step change possibly eventually led to the emergence of life as we know it — a beautiful array of animals, plants, and everything in between.
Although there have been many discussions about this theory, it has been difficult to physically create such RNA replication systems. However, in a study, Project Assistant Professor Ryo Mizuuchi and Professor Norikazu Ichihashi at the Graduate School of Arts and Sciences at the University of Tokyo, and their team, explain how they carried out a long-term RNA replication experiment in which they witnessed the transition from a chemical system towards biological complexity.
The team was truly excited by what it saw. “We found that the single RNA species evolved into a complex replication system: a replicator network comprising five types of RNAs with diverse interactions, supporting the plausibility of a long-envisioned evolutionary transition scenario,” said Mizuuchi.
Compared to previous empirical studies, this new result is novel because the team used a unique RNA replication system that can undergo Darwinian evolution, i.e., a self-perpetuating process of continuous change based on mutations and natural selection, which enabled different characteristics to emerge, and the ones that were adapted to the environment to survive.
“Honestly, we initially doubted that such diverse RNAs could evolve and coexist,” commented Mizuuchi. “In evolutionary biology, the ‘competitive exclusion principle’ states that more than one species cannot coexist if they are competing for the same resources. This means that the molecules must establish a way to use different resources one after another for sustained diversification. They are just molecules, so we wondered if it were possible for nonliving chemical species to spontaneously develop such innovation.”
So what next? According to Mizuuchi, “The simplicity of our molecular replication system, compared with biological organisms, allows us to examine evolutionary phenomena with unprecedented resolution. The evolution of complexity seen in our experiment is just the beginning. Many more events should occur towards the emergence of living systems.”
Of course, there are still many questions left to answer, but this research has provided further empirically based insight into a possible evolutionary route that an early RNA replicator may have taken on primitive Earth. As Mizuuchi said, “The results could be a clue to solving the ultimate question that human beings have been asking for thousands of years — what are the origins of life?”
Retinoic acid inhibitors mitigate vision loss in a mouse model of retinal degeneration
by Michael Telias, Kevin K. Sit, Daniel Frozenfar, Benjamin Smith, Arjit Misra, Michael J. Goard and Richard H. Kramer in Science Advances
Researchers at the University of California, Berkeley, have found that a drug once widely used to wean alcoholics off of drinking helps to improve sight in mice with retinal degeneration.
The drug may revive sight in humans with the inherited disease retinitis pigmentosa (RP), and perhaps in other vision disorders, including age-related macular degeneration. A group of scientists led by Richard Kramer, UC Berkeley professor of molecular and cell biology, had previously shown that a chemical — retinoic acid — is produced when light-sensing cells in the retina, called rods and cones, gradually die off. This chemical causes hyperactivity in retinal ganglion cells, which ordinarily send visual information to the brain. The hyperactivity interferes with their encoding and transfer of information, obscuring vision.
He realized, however, that the drug disulfiram — also called Antabuse — inhibits not only enzymes involved in the body’s ability to degrade alcohol, but also enzymes that make retinoic acid. In new experiments, Kramer and collaborator Michael Goard, who directs a lab at UC Santa Barbara (UCSB), discovered that treatment with disulfiram decreased the production of retinoic acid and made nearly-blind mice much better at detecting images displayed on a computer screen. Kramer suspects that retinoic acid plays an identical role in people with vision loss. But experiments measuring retinoic acid in the eye have not been done on humans because they would be too invasive.
Disulfiram — which is already approved for use by the Food and Drug Administration (FDA) — could establish that link.The researchers are planning to partner with ophthalmologists to conduct a clinical trial of disulfiram on patients with RP. The trial would be carried out on a small set of people with advanced, but not yet complete, retinal degeneration.
“There may be a long window of opportunity in which suppressing retinoic acid with drugs like disulfiram could substantially improve low vision and make a real difference in people’s quality of life,” said Kramer, the CH and Annie Li Chair in Molecular Biology of Diseases at UC Berkeley and a member of the campus’s Helen Wills Neuroscience Institute. “Because the drug is already FDA-approved, the regulatory hurdles are low. It wouldn’t be a permanent cure, but right now there are no available treatments that even temporarily improve vision.”
Kramer, Goard and their colleagues — Michael Telias, a former UC Berkeley postdoctoral fellow now at the University of Rochester Medical Center, and Kevin Sit of UCSB — will publish their findings. Kramer acknowledged that disulfiram may not be for everyone. When combined with alcohol consumption, the drug can have severe side effects, including headache, nausea, muscle cramps and flushing.
“If you’re on the drug, and you backslide and take a drink, you will immediately get the worst hangover of your life,” he said, “and that is what makes it a strong deterrent for drinking alcohol.”
But if disulfiram can improve vision, more targeted therapies could be sought that don’t interfere with alcohol breakdown or other metabolic functions. The researchers have already tested an experimental drug named BMS 493 that inhibits the receptor for retinoic acid, and they have also used an RNA interference technique — a type of gene therapy — to knock down the receptor. Both of these procedures also dramatically improved vision in mice with RP.
Three years ago, Kramer and his colleagues reported that retinoic acid generated sensory noise that interfered with remaining vision in mice with RP in the same way that ringing in the ears, known as tinnitus, can interfere with hearing in people who are losing vibration-sensitive cells in the inner ear. They showed that inhibiting the retinoic acid receptor reduced the noise and increased simple light avoidance behaviors in those mice. But do mice treated with the drugs actually see better?
The new study provides evidence that they do. First, when the mice were young and had healthy retinas, they were trained to recognize and respond to a simple image of black and white stripes displayed on a computer screen. A month later, after most of the rods and cones had degenerated, the image was shown once again. The investigators found that mice treated with disulfiram or BMS 493 responded quite well, even if the image was blurry. By contrast, mice receiving a placebo failed to respond, even if the image was crisp and clear.
In a second type of study, the scientists used a special microscope and a fluorescent protein indicator to light up and examine the responses of thousands of cells in the brain to much more complex visual scenes — a Hollywood movie clip, replayed many times. Individual cells in the brains of vision-impaired mice with RP responded preferentially to particular frames in the movie, and their responses were much stronger and more reliable than those of mice that had been treated with disulfiram or BMS 493.
The responses were so reliable, Kramer said, that the investigators could deduce which specific scene had triggered the cell’s response, but only in the mice that had been treated with one of the drugs. Both the behavioral results and the brain imaging results suggest that the drugs improve vision and not just light detection.
“Treated mice really see better than mice without the drugs. These particular mice could barely detect images at all at this late stage of degeneration. I think that that’s quite dramatic,” Kramer said.
In 2019, Kramer and his team laid out the mechanism behind hyperactivity caused by degeneration. They found that retinoic acid, which is well-known as a signal for growth and development in embryos, floods the retina when photoreceptors — the rods, sensitive to dim light, and the cones, needed for color vision — die. That’s because photoreceptors are packed with light-sensitive proteins called rhodopsin, which contain retinaldehyde. When the retinaldehyde can no longer be absorbed by rods and cones, it is converted to retinoic acid by an enzyme called retinaldehyde dehydrogenase.
The retinoic acid, in turn, stimulates the retinal ganglion cells by adhering to retinoic acid receptors. It’s these receptors that make ganglion cells hyperactive, creating a constant buzz of activity that submerges the visual scene and prevents the brain from picking out the signal from noise. Drug developers could seek to prevent this by developing chemicals to stop production of retinoic acid by retinaldehyde dehydrogenase, or chemicals that interfere with the retinoic acid receptor.
“If a vision impaired human were given disulfiram, and their vision got better, even a little bit, that would be a great outcome in itself. But it would also strongly implicate the retinoic acid pathway in vision loss,” Kramer said. “And that would be an important proof of concept that could drive new drug development and a whole new strategy for helping to improve vision.”
Maintenance of mitochondrial integrity in midbrain dopaminergic neurons governed by a conserved developmental transcription factor
by Federico Miozzo, Eva P. Valencia-Alarcón, Luca Stickley, Michaëla Majcin Dorcikova, Francesco Petrelli, Damla Tas, Nicolas Loncle, Irina Nikonenko, Peter Bou Dib, Emi Nagoshi in Nature Communications
Parkinson’s disease is a neurodegenerative disorder characterized by the destruction of a specific population of neurons: the dopaminergic neurons. The degeneration of these neurons prevents the transmission of signals controlling specific muscle movements and leads to tremors, involuntary muscle contractions or balance problems characteristic of this pathology. A team from the University of Geneva (UNIGE) has investigated the destruction of these dopaminergic neurons using the fruit fly as study model. The scientists identified a key protein in flies, and also in mice, which plays a protective role against this disease and could be a new therapeutic target.
Apart from rare forms involving a single gene, most Parkinson’s cases result from an interaction between multiple genetic and environmental risk factors. However, a common element in the onset of the disease is a dysfunction of mitochondria in dopaminergic neurons. These small factories within cells are responsible for energy production, but also for activating the cell’s self-destruct mechanisms when damaged.
The laboratory of Emi Nagoshi, Professor in the Department of Genetics and Evolution at the UNIGE Faculty of Science, uses the fruit fly, or Drosophila, to study the mechanisms of dopaminergic neuron degeneration. Her group is particularly interested in the Fer2 gene, whose human homolog encodes a protein that controls the expression of many other genes and whose mutation might lead to Parkinson’s disease via mechanisms that are not yet well understood. In a previous study, this scientific team demonstrated that a mutation in the Fer2 gene causes Parkinson’s-like deficiencies in flies, including a delay in the initiation of movement. They had also observed defects in the shape of the mitochondria of dopaminergic neurons, similar to those observed in Parkinson’s patients.
Since the absence of Fer2 causes Parkinson’s disease-like conditions, the researchers tested whether — on the contrary — an increase in the amount of Fer2 in the cells could have a protective effect. When flies are exposed to free radicals, their cells undergo oxidative stress which leads to the degradation of dopaminergic neurons. However, the scientists were able to observe that oxidative stress no longer has any deleterious effect on the flies if they overproduce Fer2, confirming the hypothesis of its protective role.
“We have also identified the genes regulated by Fer2 and these are mainly involved in mitochondrial functions. This key protein therefore seems to play a crucial role against the degeneration of dopaminergic neurons in flies by controlling not only the structure of mitochondria but also their functions,” explains Federico Miozzo, researcher in the Department of Genetics and Evolution and first author of the study.
To find out whether Fer2 plays the same role in mammals, the biologists created mutants of the Fer2homolog in mouse dopaminergic neurons. As in the fly, they observed abnormalities in the mitochondria of these neurons as well as defects in locomotion in aged mice. “We are currently testing the protective role of the Fer2 homolog in mice and results similar to those observed in flies would allow us to consider a new therapeutic target for Parkinson’s disease patients,” concludes Emi Nagoshi.
Inhalable SARS-CoV-2 Mimetic Particles Induce Pleiotropic Antigen Presentation
by Atip Lawanprasert, Andrew W. Simonson, Sarah E. Sumner, McKayla J. Nicol, Sopida Pimcharoen, Girish S. Kirimanjeswara, Scott H. Medina in Biomacromolecules
An inhalable ‘aerogel’ loaded with DNA that encodes for the SARS-CoV-2 spike protein successfully induces an immune response against COVID-19 in the lungs of mice, according to new research conducted at Penn State. The team said its aerogel could be used to create an inhalable vaccine that blocks SARS-CoV-2 transmission by preventing the virus from establishing an infection in the lungs.
“There are many potential advantages of an inhalable formulation compared to an injectable vaccine,” said Atip Lawanprasert, graduate student in biomedical engineering and a lead author of the study. “One is avoidance of needles. Inhalable vaccines might be able to help increase the rate of vaccination because so many people are afraid of injections. No matter how high the efficacy of a vaccine, if people don’t get it, then it’s not useful.” Scott Medina, assistant professor of biomedical engineering, Penn State, added that inhalable vaccines may be more shelf stable than traditional vaccines.
“Importantly,” Medina said, “inhalable vaccines may induce an antibody response locally in the lungs where it can potentially neutralize and clear the virus before it fully infects the host and causes symptoms.”
By contrast, Girish Kirimanjeswara, associate professor of veterinary and biomedical sciences, explained that the injectable COVID-19 vaccines induce a systemic immune response, which is effective at fighting infections with SARS-CoV-2, but not as potent as an inhalable vaccine would be in stopping the infection at the location of the virus’s entry into the body.
“The current vaccines are not very good at preventing transmission because they allow the virus to replicate in the body, even for a short period, and then transmit to other individuals,” said Kirimanjeswara. “An inhalable vaccine would elicit local immunity at the primary site of infection, where SARS-CoV-2 could be rapidly neutralized and eliminated without the inflammatory response characteristic of systemic vaccination.”
Previously, the team had developed and patented a gel-like material, called an ‘aerogel,’ as a vehicle for delivering antimicrobials to the lungs to treat bacterial respiratory infections, particularly tuberculosis.
“When the pandemic started, we decided to develop an inhalable formulation for COVID-19 by combining our aerogel with a nucleic acid-encoded antigen — specifically, DNA that encodes the SARS-CoV-2 proteins,” said Medina.
The researchers developed their COVID-19 formulation, which they call CoMiP (coronavirus mimetic particle), to target alveolar macrophages — immune cells in the respiratory tract that ingest foreign particles.
“Alveolar macrophages represent attractive targets for inhalable vaccines because they are abundant within the lungs, and previous evidence has suggested that they may be important in early COVID-19 pathogenesis,” said Medina.
Specifically, he explained, alveolar macrophages may be one of the first cells to become infected by SARS-CoV-2 when the virus is inhaled.
“Alveolar macrophages are one of our key defenders against viral infection because they serve to present antigens to the rest of the immune system,” said Medina.
The scientists designed their CoMiPs to be rapidly ingested by alveolar macrophages, after which the macrophages would interpret the viral antigen and begin to express the viral proteins encoded in the DNA.
“You are essentially tricking the macrophage into interpreting this DNA and expressing this foreign spike protein,” said Medina. “Once it expresses the foreign protein, it shows it to the rest of the immune system so the immune system can learn to recognize the protein in the event of a SARS-CoV-2 infection.”
In the laboratory, when the scientists incubated their CoMiPs with cells designed to mimic naive alveolar immune cells, they found that the macrophages readily internalized the CoMiPs. Next, they optimized the formulation of the CoMiPs to identify the maximum safe dose in cells in vitro. They found that >80% of cells remained viable at a dose of ?0.01 mg/mL.
To test the efficacy of the CoMiP vaccine, the team immunized mice via an intranasal installation of the vaccine, followed by a booster dose two weeks later. Next, they collected serum samples from the animals on days 14 and 28 post vaccination and booster, respectively. They analyzed these samples for systemic immune responses and found no statistically significant change in systemic antibody levels between CoMiP-treated animals and control animals at either sampling time point. To explore nose, throat and lung immune responses, the researchers collected samples from immunized mice 30 days after vaccination to assess differences in the total and spike-protein specific lung mucosal IgA antibodies. They found a significant increase in the total IgA for mice vaccinated with CoMiPs, but IgA specifically targeting the SARS-CoV-2 spike protein was lower than expected for the vaccinated animals.
“On the benchtop, outside of the animal, we saw pretty good expression of the proteins,” said Medina. “And then when the CoMiPs were delivered into the animal, we saw an increase in antibodies in the lung that may provide some protection, but it was not to the extent that we would like. It’s encouraging data, but there is more optimization to be done.”
The team plans to continue to research the use of CoMiPs to protect against COVID-19 In addition, Kirimanjeswara noted, “Transmission blocking, inhalable vaccines can also be translated to multiple other viruses, such as flu, so our CoMiP has the potential to be widely applicable.”
Phase-separating peptides for direct cytosolic delivery and redox-activated release of macromolecular therapeutics
by Yue Sun, Sze Yi Lau, Zhi Wei Lim, Shi Chieh Chang, Farid Ghadessy, Anthony Partridge, Ali Miserez in Nature Chemistry
Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a novel method of delivering drugs into human cells using large biological molecules, by first encasing them in a protein-based microdroplet.
This discovery promises to be faster, safer, more effective, and better suited for gene therapy, cancer treatment, and vaccine delivery, including mRNA-based vaccines such as those currently used for Covid-19 vaccinations by Pfizer and Moderna.
These microdroplets, made up of small proteins named peptides, can encase large biomacromolecules that carry drugs inside them. In doing so, they allow these biological molecules to enter cells, something the molecules cannot do by themselves. Biomacromolecules are large biological molecules such as nucleic acids (DNA, mRNA), proteins and carbohydrates. They are of great research interest as drug carriers, as they can carry a large amount of drugs, are nontoxic, able to target specific sites, and do not trigger the body’s immune response. This makes them preferable and advantageous over synthetic carriers currently used in the market. However, their large size and inability to pass through the cell membrane have held them back from widespread clinical use.
Now, the NTU research team, led by Professor Ali Miserez from the School of Materials Science & Engineering and the School of Biological Sciences, showed in lab experiments that their method of first encasing drug-carrying biomacromolecules in protein-based microdroplets lets them reliably and effectively enter cells, overcoming the main challenge of cell entry.
“Biomacromolecules are promising therapeutic prospects for the treatment of various diseases as they have high potency, specificity, and are very safe,” said Prof Miserez. “Despite this broad potential, biomacromolecules suffer from a major drawback: they are impermeable to the cell membrane and thus cannot penetrate the cell by themselves. They need help, which is where our platform comes into place.”
The research team has filed two patents based on their published study and are working to commercialise their drug delivery platform method through NTUitive, the University’s innovation and enterprise company. The development of the team’s novel drug delivery system is aligned with NTU’s commitment to innovation in its recently announced 2025 strategic plan, which aims to translate research into products and outcomes that enhance the quality of life.
The researchers synthesised a peptide derived from squid beak to form the microdroplet due to its biological origin, high efficiency in storing molecules, and low toxicity. They were then able to entrap biomacromolecules inside it through a process called liquid-liquid phase separation (LLPS). This LLPS process, similar to how oil and water can mix together yet easily separate into two distinct liquids, forms what is known as a coacervate.
This coacervate is able to merge into the cell membrane, although the exact reason why is currently unknown. “Presumably, the liquid-like properties of coacervates achieved via the liquid-liquid phase separation process is critical in their ability to cross the cell membrane, although the precise entry mechanism is still unclear and currently under investigation,” said the paper’s first author, NTU PhD student Yue Sun. Crucially, this discovery allows biomacromolecules to avoid endocytosis — the process where cells allow foreign substances to enter by surrounding it with a protective membrane.
Traditional drug delivery methods cannot cross into the cell membrane without first being caught by the cell and wrapped within a ‘bubble’ of cell membrane, or endosome. Therefore, these types of drug packages must also be encoded with further instructions to ‘escape’ the endosome in order for them to efficiently release the drugs within the cell. The team’s coacervates are able to smoothly cross the cell membrane without triggering endocytosis. Once inside the cell, the carrier droplets disintegrate and release the biomacromolecules to do their job of treating various illnesses, including cancer and metabolic diseases.
“You can think about these droplets as molecular ‘Trojan Horses’: they trick the cells into letting them enter, and once inside, they deliver the biomacromolecular ‘soldiers’ that target the disease,” said Prof Miserez.
Bypassing endocytosis is crucial as it reduces drug efficacy. Since the peptide microdroplets developed by the NTU team can bypass this process to enter the cell unhindered, their drug cargo can operate at full strength, said Prof Miserez.
In lab experiments, the team was able to successfully deliver fluorescent proteins, which are commonly used to demonstrate the efficiency of drug carriers, as well as the protein drug saporin through this method. By themselves, these proteins cannot enter the cell. The protein-based cargo was not only able to successfully enter and be released into the cells, but also maintained its bioactivity and efficacy. The team discovered that the cell entry process had a 99 per cent success rate compared to the 50–70 per cent of current commercially-available synthetic carriers. The research team demonstrated that a wide range of biomacromolecules can be loaded into their microdroplets, from small peptides to enzymes to mRNAs. This makes it viable as a universal drug delivery system. All current delivery systems have to be created separately for different types of drugs.
“Using our peptide droplets as a drug delivery system does away with the need to fabricate drug carriers that have to escape the endosome in order to deliver their cargo,” said Prof Miserez. “Furthermore, the drawback of such drug carriers is that they also have to be tailored to the particular drug that is being used or delivered. Such fabrication methods can be complex, time-consuming, and often contain organic solvents that reduce the bioactivity and efficiency of the drug cargo.”
“However, our peptide droplets can work as a universal delivery system without the need for individual adjustment. One delivery system for a whole range of proteins of various sizes, from big to small, and that can carry both positively- and negatively-charged proteins, is very appealing,” added Prof Miserez.
This discovery can lead to better targeted drug delivery systems that are cheaper, safer, and more effective.
The researchers were also able to deliver mRNA molecules into cells with this method. This opens the potential of using mRNA in gene therapy, a possible treatment for serious diseases such as cancer, genetic disorders, or infectious diseases.
“The versatility of drug delivery and subsequent release allows these coacervates to deliver a single or a combination of macromolecular drugs, making this delivery platform very promising for the treatment of variety of illnesses such as cancer, and metabolic and infectious diseases,” said Prof Miserez.
Commenting independently on the study, Dr Mahmood Ahmed, Chief Scientific Officer at artificial intelligence drug development firm Biotech Talo Labs, said: “The exciting findings reported by the NTU scientists provide a path to addressing some key gaps in delivering a range of therapeutic modalities to the site of action. The data reported here demonstrates the potential of these biocompatible coacervates to traverse cell membranes and deliver diverse sets of large molecule entities, with the ability to tune and control the release of payload. Continued development of this discovery will further strengthen the translational utility of these unique coacervates and establish a transformational delivery technology platform.”
The team has filed two patents related to the study. The first patent is the team’s method of preparing the peptides into microdroplets for them to function as drug carriers. The other patent is for the method allowing the microdroplets to enter cells and then disintegrate once inside the cells such as to release the packaged drugs. While real-world applications remain at least five years away, the scientists say their research has garnered initial interest from pharmaceutical and drug development companies. The team is looking to further their research by beginning animal studies this year.
Odorant-receptor-mediated regulation of chemosensory gene expression in the malaria mosquito Anopheles gambiae
by Sarah E. Maguire, Ali Afify, Loyal A. Goff, Christopher J. Potter in Cell Reports
In what they call surprise findings, Johns Hopkins Medicine scientists report that — unlike fruit flies — mosquitoes’ odor sensing nerve cells shut down when those cells are forced to produce odor-related proteins, or receptors, on the surface of the cell. This “expression” process apparently makes the bugs able to ignore common insect repellents.
In contrast, when odor sensors in fruit flies are forced to express odor receptors, it prompts flight from some smelly situations. The findings reveal the variation in insect olfactory systems, say the researchers, and add to the growing body of research aimed at improving methods to repel mosquitoes from human skin.
Mosquito bites not only create irritating swelling and itching, but, worldwide, they play a role in spreading rampant and often lethal diseases such as malaria and dengue fever, as well as Zika virus infections.
“When experiments don’t go as predicted, there’s often something new to be discovered,” says Christopher Potter, Ph.D., associate professor of neuroscience at the Johns Hopkins University School of Medicine, describing the new study. It turns out, he says, that, “Mosquitoes are so much trickier than we thought.”
Potter and former postdoctoral fellow Sarah Maguire, Ph.D., designed their research project suspecting they’d find that mosquitoes have the same reaction as fruit flies when their new odor sensors are forced to be expressed. Other research showed that when odor receptors in fly olfactory neurons are abnormally expressed, a new signal, based on the expressed odor receptor, is delivered to the brain, and the bugs move away from an offending odor.
The researchers then tested this same scenario on female Anopheles mosquitoes, whose bite transmits parasites that cause malaria in humans. The idea was that if researchers could push mosquito odor neurons into a similar expression state, triggered by odorants already on the skin, the mosquitoes would avoid the scent and fly off.
In the mosquito experiments, the researchers used mosquitoes genetically modified to overexpress an odor receptor called AgOR2, which responds to animal odorants found on humans. By measuring the neuron activity generated by mosquitoes’ odor receptors, the scientists found that the mosquitoes with overexpressed AgOR2 receptors had very little response to common animal scents, benzaldehyde and indole, as well as chemical odorants in general.
“AgOR2 overexpression threw a wrench in the whole system by inactivating olfactory receptors in these mosquitoes,” says Potter.
Next, working with Johns Hopkins scientist Loyal Goff, Ph.D., the researchers did additional experiments to determine the level of messenger RNA output in olfactory neurons forced to express the AgOR2 gene, an indicator of the health of olfactory neurons. They determined this by using a technique called RNA sequencing which measures the amount of RNA, an intermediary between DNA and its protein output, in neurons found in the antennae of normal and the genetically modified mosquitoes. They found that mosquitoes genetically modified to overexpress AgOR2 had up to 95% less expression in their natural olfactory receptors as compared with unmodified mosquitoes. Finally, in the current study, the researchers tested how mosquitoes modified to overexpress AgOR2 responded to odorants in common insect repellents, such as lemongrass. They found that the genetically modified mosquitoes were able to ignore insect repellents.
The researchers suspect that the odor receptor shutdown may be a kind of failsafe in mosquitoes, ensuring that only one type of odorant receptor is expressed at a single time. Since Anopheles mosquito olfactory systems continue to develop into adulthood, about eight days after hatching, the researchers speculate that the insects’ olfactory neurons might be susceptible to which olfactory receptors to express, based on their surrounding environment. This type of flexibility in a mosquito’s olfactory neurons may allow the mosquito to adapt to its odor environment. The researchers are conducting experiments to test this theory. Potter hopes that the current findings may advance the search for methods that can trick the mosquito olfactory system into no longer preferring the smell of humans.
Rescued back from extinction in the wild: past, present and future of the genetics of the Arabian oryx in Oman
by Qais Al Rawahi, Jose Luis Mijangos, Mehar S. Khatkar, Mohammed A. Al Abri, Mansoor H. AlJahdhami, Jennifer Kaden, Helen Senn, Katherine Brittain, Jaime Gongora in Royal Society Open Science
In a world-first, the DNA of a vulnerable species, the iconic Arabian Oryx, has been decoded. An international team led by the University of Sydney undertook this project to ensure the survival of the species, by using the genetic data to inform breeding programs.
The Arabian oryx, a kind of antelope, became extinct in the wild in 1972 due to hunting and poaching. However, it continued to exist in captivity through breeding programs at the Phoenix Zoo and by private collectors in Saudi Arabia (indeed, it was the first animal to be rescued from extinction in the wild). It was historically — and remains — a cultural and national icon in the Gulf region. A decade later, the species was ‘rewilded’ and today, wild populations totalling 1,200 animals exist in around the world, mainly on the Arabian Peninsula. There are 6,000–7,000 animals in captivity, 600 of which are in the Al-Wusta Wildlife Reserve, in Oman.
According to the IUCN Red List of Threatened Species, the Arabian oryx continues to face a high risk of extinction in the wild. Yet, until now, no breeding strategies that account for the genetic diversity have been devised. Associate Professor Jaime Gongora, his former PhD student Qais Al Rawahi, and his colleagues decided to address this by analysing the population’s DNA and proposing breeding strategies based on the results.
“There is more to the preservation of the Arabian oryx than conservation,” Associate Professor Gongora said. “Historically and now, it has strong cultural significance in the Arabian Peninsula due to its unique physical features and strength, enabling it to live in harsh desert environments. It has even become a national icon in Saudi Arabia, Oman, Qatar, and the United Arab Emirates. That’s why we are working so hard to ensure it survives — for the oryx itself and to keep this cultural connection alive.”
“This work in such an iconic species could serve as a benchmark for the long-term sustainability of other conservation programs. This includes those taking place at the Al-Wusta Wildlife Reserve involving the Sand Gazelle, the Mountain Gazelle and the Nubian Ibex.”
Arabian oryx are unique animals distinguished by the length of their horns, which can grow up to one metre. They can travel 75km a day, searching for food, and are known for their ‘sixth sense’: they can sense the location of incoming rain and move towards it to drink, as well as consume plants that thrive in moister conditions, like acacias. With a lifespan of between 15 and 20 years, they are a key food source for other species on the Arabian Peninsula including striped hyenas, Arabian wolves, and lynxes.
The researchers gathered and tested genetic samples from 138 Arabian oryxes at the Al-Wusta Wildlife Reserve, as well as 36 historical samples from the Phoenix Zoo — the offspring of a herd established there in the 1970s. They studied the maternally inherited mitochondrial DNA and biparentally inherited single nucleotide polymorphisms — genetic variations used to identify species. To their relief, the Arabian oryx’s gene pool was moderately diverse, meaning that herds can respond to changing environments and maintain good health. In fact, at 58 percent of the total diversity, the current-day sample was more genetically diverse than the historical ones. “This means that conservation strategies based on random mating could be reasonably successful,” said the lead author of the study, Associate Professor Gongora.
Yet there was room for improvement: they discovered three ancestral groups, but their genetics were not evenly distributed across the current-day herds in the wildlife reserve. Based on this, they suggest a targeted breeding strategy whereby females can breed with males from the other genetic lineages. “To ensure the survival of the species, it’s not just about population size — it’s about genetic diversity,” Associate Professor Gongora said.
A “spindle and thread” mechanism unblocks p53 translation by modulating N-terminal disorder
by Margit Kaldmäe, Thibault Vosselman, Xueying Zhong,et al in Structure
The p53 protein protects our cells from cancer and is an interesting target for cancer treatments. The problem is, however, that it breaks down rapidly in the cell. Researchers at Karolinska Institutet in Sweden have now found an unusual way of stabilising the protein and making it more potent. By adding a spider silk protein to p53, they show that it is possible to create a protein that is more stable and capable of killing cancer cells.
P53 plays a key role in the body’s defence against cancer, in part by discovering and preventing genetic mutations that can lead to cancer. If a cell is lacking functional p53, it quickly becomes a cancer cell that starts to divide uncontrollably. Researchers around the world are therefore trying to develop cancer treatments that in some way target p53.
“The problem is that cells only make small amounts of p53 and then quickly break it down as it is a very large and disordered protein,” says the study’s last author Michael Landreh, researcher at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet. “We’ve been inspired by how nature creates stable proteins and have used spider silk protein to stabilise p53. Spider silk consists of long chains of highly stable proteins, and is one of nature’s strongest polymers.”
In a collaborative project with, amongst others, Jan Johansson and Anna Rising at KI’s Department of Biosciences and Nutrition, who use spider silk in their research, the researchers attached a small section of a synthetic spider silk protein onto the human p53 protein. When they then introduced it into cells, they found that the cells started to produce it in large quantities. The new protein also proved to be more stable than ordinary p53 and capable of killing cancer cells. Using electron microscopy, computer simulations, and mass spectrometry, they were able to show that the likely reason for this was the way the spider silk part managed to give structure to p53’s disordered sections.
The researchers now plan to study the protein’s structure in detail and how its different parts interact to prevent cancer. They also hope to find out how the cells are affected by the new potent p53 protein and how well they tolerate its spider-silk component.
“Creating a more stable variant of p53 in cells is a promising approach to cancer therapy, and now we have a tool for this that’s worth exploring,” says co-author and senior professor Sir David Lane at Karolinska Institutet. “We eventually hope to develop an mRNA-based cancer vaccine, but before we do so we need to know how the protein is handled in the cells and if large amounts of it can be toxic.”
Sir David Lane was one of the discoverers of the p53 protein in the late 1970s. P53 has been called the guardian of the genome since it can stop cells with DNA damage turning into cancer cells. Mutations of the p53 gene are found in roughly half of all cancer tumours, which makes it the most common genetic change in cancer.
A transchromosomic rat model with human chromosome 21 shows robust Down syndrome features
by Yasuhiro Kazuki, Feng J. Gao, Miho Yamakawa, et al in The American Journal of Human Genetics
In pursuit of better ways to test new therapies and further explore the impacts of the unique genetics associated with Down syndrome, researchers at Johns Hopkins Medicine and Tottori University in Japan have genetically engineered and characterized what is believed to be the first rat model of Down syndrome.
Scientists have long sought ways to improve medical care for people with Down syndrome, especially those suffering the physical and mental challenges that are hallmarks of the condition. These include a higher risk of heart defects, gastrointestinal problems and difficulties with learning and memory.
“Developing an animal model that shares these features with human Down Syndrome will allow us to test therapeutics more efficiently, with higher odds of developing ones that can work in people,” says Roger H. Reeves, Ph.D., professor of physiology at the Johns Hopkins University School of Medicine.
At its root, Down syndrome is an outcome of a so-called chromosomal “trisomy,” or tripling. A typical human cell has 23 pairs of chromosomes, which contain genetic instructions that govern its inner workings and how it interacts with the rest of the body. Down syndrome occurs when a person is born with an extra partial or entire copy of the 21st chromosome, a condition called trisomy 21. This extra chromosome’s effects are expressed widely across the body and its impacts vary among individuals.
Rats do not — as humans do — randomly produce offspring with extra 21st chromosomes, so the researchers set out to accomplish a complicated feat of genetic engineering to generate rats with an additional 21st chromosome. The process included transferring the 21st chromosome from human white blood cells to mouse cells, then to chicken cells, then hamster cells and, finally, into a rat embryo. At each transfer, the researchers made different genetic modifications, including the addition of a green glowing protein, which under ultraviolet light identified rats with extra 21st chromosomes.
Reeves and his team then assessed the genetically engineered rats’ cognition and physical characteristics for traits associated with an extra 21st chromosome. To test the rats’ learning and memory, for example, the researchers conducted standardized maze tests with the genetically engineered rats.
Rats with an extra 21st chromosome took longer to solve the maze than genetically typical rats. They also had a harder time remembering the maze’s solution when challenged to solve the same puzzle over four consecutive days. Other cognitive tests reflected that, overall, the rats with an extra 21st chromosome were more anxious and hyperactive than rats without the extra chromosome. These results are consistent with assessments in people with Down syndrome, who report having higher rates of anxiety, attention disorders and learning and memory impairments.
In anatomical studies, the researchers also found that a brain structure called the cerebellum was significantly smaller in rats with an extra 21st chromosome. The cerebellum is central to the body’s core functions, including message processing across the brain, and is much smaller in people with Down syndrome.
“There is already progress in developing pharmaceuticals that help the cerebellum grow in mice,” says Reeves. “If we eventually translate that into medicines for humans, we may be able to help people with Down syndrome improve their learning and memory skills.”
The distinct facial differences in people with Down syndrome — such as flatter faces, almond-shaped eyes and smaller heads — were also present in the rats. While people cannot look at a rat and determine whether its face looks different from a typical rodent, a computer program can measure the differences. The skulls were scanned in a CT machine and the data added to a computer modeling program, which revealed that the rats had shortened snouts. The bones making up these features in the rat skull correspond to those in human skulls that make up the characteristic facial “flattening” in people with Down syndrome. Finally, 17% of the rats with an extra 21st chromosome had an abnormality of heart ventricles that is similar to one diagnosed in up to 21% of children with Down syndrome.
Drosophila functional screening of de novo variants in autism uncovers damaging variants and facilitates discovery of rare neurodevelopmental diseases
by Paul C. Marcogliese, Samantha L. Deal, Jonathan Andrews, J. Michael Harnish, et al in Cell Reports
About 1 in 44 children in the U.S. are diagnosed with autism spectrum disorder (ASD) by the age of 8, according to the 2018 Centers for Disease Control and Prevention surveillance. How a child’s DNA contributes to the development of ASD has been more of a mystery. Recently, clinicians and scientists have looked more closely at new, or de novo, DNA changes, meaning they only are present in affected individuals but not in the parents. Researchers have seen that these changes could be responsible for about 30% of ASD. However, which de novo variants play a role in causing ASD remains unknown.
Researchers at Baylor College of Medicine and Texas Children’s Hospital have taken a new approach to looking at de novo ASD genetic variants. In this multi-institutional study, they applied sophisticated genetic strategies in laboratory fruit flies to determine the functional consequences of de novo variants identified in the Simons Simplex Collection (SSC), which includes approximately 2,600 families affected by autism spectrum disorder. Surprisingly, their work also allowed them to uncover a new form of rare disease due to a gene called GLRA2.
“ASDs include complex neurodevelopmental conditions with impairments in social interaction, communication and restricted interests or repetitive behaviors. In the current study, we initiated our work based on information from a cohort of ASD patients in the SSC whose genomes and those of their families had been sequenced,” said co-corresponding author Dr. Shinya Yamamoto, assistant professor of molecular and human genetics and of neuroscience at Baylor and investigator at the Jan and Dan Duncan Neurological Research Institute at Texas Children’s. “Our first goal was to identify gene variants associated with ASD that had a detrimental effect.”
The team worked with the fruit fly lab model to determine the biological consequences of the ASD-associated variants. They selected 79 ASD variants in 74 genes identified in the SSC and studied the effect of each ASD-linked gene variant compared to the commonly found gene sequence (reference) as a control, from three different perspectives. Co-first author, Dr. Paul Marcogliese, postdoctoral fellow in Dr. Hugo Bellen’s lab, coordinated the effort on knocking out the corresponding fly gene, and examining their biological functions and expression patterns within the nervous system. They then replaced the fly gene with the human gene variant identified in patients, or the reference sequence, and determined how it affected biological functions in the flies.
Working with fruit flies carrying either the reference human gene or the variant forms, co-first author Dr. Jonathan Andrews, postdoctoral fellow in Dr. Michael Wangler’s lab at Baylor, was the point person investigating how these gene variants affected fly behavior. As ASD patients exhibit patterns of repetitive behavior as well as changes in social interaction, he evaluated the effect of the patient variants on an array of social and non-social fly behaviors, such as courtship and grooming. “It’s interesting to see that manipulation of many of these genes also can cause behavioral changes in the flies,” Andrews said. “We found a number of human genes with ASD variants that altered behavior when expressed in flies, providing functional evidence that these have functional consequences.”
The third approach involved overexpressing the genes of interest in different tissue types in fruit flies. Co-first authors Samantha Deal and Michael Harnish, two graduate students in Baylor’s Graduate Programs in Developmental Biology and Genetics and Genomics, respectively, working in Dr. Yamamoto’s lab, headed these studies. “While some gene variants may lead to conditions because they produce defective proteins, others may lead to disease because they cause overabundance or aberrant function of a particular protein, which can disrupt biological processes. We investigated whether overexpressing gene variants found in individuals with ASD might explain the detrimental effect for some of these genes,” Deal said.
Altogether, the team generated more than 300 fly strains in which they conducted functional studies of human gene variants associated with ASD. Their screen elucidated 30 ASD-linked variants with functional differences compared to the reference gene, which was about 40% of the genes for which they were able to perform a comparative functional assay.
“Some of the variants we studied had functional consequences that were moderately or clearly predicted to be disruptive, but other variants were a surprise. Even the state-of-the-art computational programs couldn’t predict they would have detrimental effects,” said Yamamoto. “This highlights the value of using multiple, complementary approaches to evaluate the functional consequences of genetic variants associated with ASD or other conditions in a living animal. Our fruit fly approach is a valuable tool to investigate the biological relevance of gene variants associated with disease.”
In addition, the wealth of data generated by the researchers revealed gene variants not previously connected with other neurodevelopmental diseases and uncovered new aspects of the complexity of genetic diseases.
“GLRA2 was one gene we specifically focused on to follow up,” Dr. Ronit Marom, assistant professor of molecular and human genetics at Baylor and lead clinician of this work said. “We identified 13 patients, five males and eight females, carrying rare variants of this X-linked gene that had not been established as a neurological disease gene before. Furthermore, males and females carried variants with different types of functional consequences and the spectrum of neurological characteristics among these 13 patients was different between the two groups. For instance, many of the boys carried loss of function variants and had ASD, while the girls did not. They mainly presented with developmental delay as the main characteristic of their condition, and carried gain of function variants.”
“The picture that emerges is that ASD may not be one disorder involving many genes. It may actually be hundreds of genetic disorders, like those caused by certain GLRA2 variants,” said Wangler, assistant professor of molecular and human genetics at Baylor and co-corresponding author of the work. “We think that this information is important to physicians seeing patients with ASD.”
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