The Nature of (Un)Productivity
Hard Work, Failure, and Cellular Quiescence
Four years of lectures, labs, late-night study sessions and group projects had all been leading up to now. My grades were finalized, my GPA came out beautifully and the recommendation letters had worked their magic. I was about to enter my PhD program and for months now eagerly shared my good news with anyone who would listen.
“I’ll actually be starting my PhD program early. I was accepted into a lab already, so I’ll begin my research project in June to get a head start before my classes start in August.”
At the time, I thought I was modestly acknowledging my achievements, and the praise I received fed the cycle of self-adulation. My ego filtered out any sarcasm or withdrawal and all I heard was admiration. “Ohhhh, that’s WON-derful!”
“It’ll really give me some extra time to get a head start on getting some data for my dissertation.” Just think of how productive I would be over the summer! No classes, no outside responsibilities, no TA appointment, just me in the lab. I could imagine myself walking into my graduate classes that fall, meeting the other students in my program and knowing that I already had something they didn’t have yet — proof of my productivity. Proof of my contribution to science, proof that I was a worthwhile member of the university. This productivity could be enough to give me the advantage of graduating earlier than the departmental average of 5.5 years. After all, productivity and efficiency are the keys to success.
The wooden chair was sticky against my legs, and as I looked at the other faces at my table, I could tell I wasn’t the only one bored out of my mind. Good thing this was the last time I’d have to sit in this Hall, and listen to one of his talks. Commencement was tomorrow morning, and the assistant director of the IUP Honors College was giving us his final well-wishes. We had rehearsed the ceremony, handled all the administrative stuff, and really, what could he possibly have to say at this point that would be news to me?
“I remember when I got married the first time,” he began.
“Great, another tale of his lovelorn misadventures.” He loved to tell his sob stories. He took every opportunity to project an image of himself as an angsty lover.
“My friend told me something that stuck with me all these years. He told me ‘yeah, marriage will be a beautiful part of your life. You’ll do that for a while.’”
He paused for the snickers and chuckles, grinning along with us himself.
“But he was right. As much as I didn’t want to hear it, I needed to hear it. We think that if something changes or goes away, that it has failed. But success and failure are not so straightforward. A lesson I’ve had to learn over and over is to redefine my measures of success.”
It sounded something you’d tell a chubby girl who didn’t get asked to prom. Successful people don’t need this advice, only people who fail need it. I wouldn’t need this advice, because I was setting myself up to succeed. Productive and efficient, I was surely on the fast track to success. I walked in commencement the next day, moved out of my campus housing later that night and was off to start my PhD program early, precocious prodigy that I was.
On my first day of grad school I met with my research advisor and sat in his office as he drew a flow chart of my work for the summer. We had already talked about the basic idea of my project: characterize the biochemical activities of a specific protein found in human cells. Very little was known about this protein at the time, except that its amino acid sequence, typically an indicator of a protein’s function in the cell, very closely matched a well-characterized family of human proteins. The other members of this family of proteins have very specific, indispensible roles in DNA replication, which is the process of making a new copy of DNA to be passed on to a daughter cell during cell proliferation. So with a clue that this protein probably performs a function important for DNA replication, my dissertation would investigate what biochemical functions it actually performs.
When working with any naturally occurring material, like a protein found in a cell, the first step is separating that material from everything surrounding it. For me, that meant separating the protein not only from the cell wall, cell organelles and DNA, but also from every other protein produced by the cell. Biochemists have developed a number of tools for purifying proteins. Typically, these methods involve passing a solution containing all the contents of a cell sample through tiny beads that have molecules attached all over their surface. These molecules are chosen based on their predicted attraction to the target protein. Specifically, they are chosen because they are predicted to be more attracted to the target protein than all the other proteins in the mixture. If the predicted attraction is real, the target protein will “stick” to the molecules all over the surface of the beads, while all the other cell contents flow past. Some purification methods simply separate proteins based on size. More sophisticated methods involve cloning a “tag” made of a short amino acid sequence onto the end of a protein, and then attaching a molecule to the purification beads that has a strong attraction to that tag. For most proteins, a series of several of these purification methods is needed to produce a protein sample pure enough for biochemical analysis.
Since my protein had not been purified by conventional methods (it had been purified using insect cell expression, which I eventually attempted with no favorable outcome. But that’s a whole other story.), my first task was finding the best sequence of purification methods to produce a pure sample. But it wouldn’t completely be a shot in the dark. We knew the amino acid sequence, which gave us some clues about the protein’s affinities, and told us some basic information like what pH to use to ensure protein stability. Even so, my advisor prepared me for “about a month” of trial-and-error before I would have a pure protein sample. After that, the sky would be the limit on my productivity.
A few weeks before classes were scheduled to start, I started to realize I wasn’t going to be past the trial-and-error period that summer. When I saw my family over Labor Day weekend I felt hesitant to even talk about my PhD program. A few months before, all I could do was burst with exuberance. “I am going to be a PhD candidate!” But that candidacy hinged on one thing: productivity. Could I convince my dissertation committee that I was a meaningful contributor to the field if I had no publishable data? I was starting to envision 2 or 3 years in the future, having to explain to my family that no, the PhD hadn’t worked out.
Three years down the road, I was still in the trial-and-error period. What infuriated me the most was that I was doing everything right. I was able to convince my dissertation committee at my 2.5-year evaluation that I had a well-designed, worthwhile project, but I just had a string of unlucky string of experiments. They agreed to keep me as part of the department, due in large part to my advisor’s support. My experimental planning was careful, I worked diligently; the payoff simply hadn’t arrived yet.
The benefit of the doubt my committee afforded me did little to salve my disillusionment. I had been taught an algorithm and I believed it to be true. The algorithm is: if you work hard, you will make a product. If that algorithm was false, I had no idea what I could believe. And if I had no product from my work, what was the purpose of all my work? What was my purpose?
The years that followed were a mindless, empty sequence of going through the motions. I have few distinct memories of days or moments; the whole time span seems like a blur or a haze in my memory. Each day was a repetition of the day before and I expected nothing new, fresh or different. I would go to work, do my labwork, expecting nothing but failure, and keeping a forced smile on my face. And then about every seventh or tenth day, I completely broke down. The breakdown manifested itself in a variety of self-destructive behaviors, but the universal characteristic was shame. And lots and lots of tears. This was a failure on my part, and try as I might to distract myself, I couldn’t avoid the sense of guilt, shame and self-hatred I felt. I had one purpose as a graduate student: produce results efficiently. If this result was absent, there was no purpose left.
We talk about production and efficiency not only in a human context, but in a biological context. Our vocabulary for discussing cells, genes and proteins invokes machine-like metaphors: biology textbooks emphasize the importance of the cell cycle, the process by which a cell produces new daughter cells. This process must be tightly controlled, with each step proceeding only after the successful completion of the previous step, efficiently producing new cells. This process is central to the growth and health of the organism. Even once adulthood is reached, organ regeneration is a constant need, requiring continuous production of new cells.
This role of the cell as a cell-making factory has a very obvious purpose within the human body. We can quickly identify why proliferating cells are important in the body. The difficulty, however with the cell-as-factory metaphor is that it fails to explain the purpose of non-proliferating cells. The cell cycle contains an additional mode of life that is not part of cellular reproduction and typically receives 2–3 sentences in a biology textbook, although the vast majority of human cells exist in this state at any given time (1). Sometimes a tiny exit ramp is drawn off of the cell cycle diagram, leading to “G0” phase, or “quiescence.” This is a reversible state of rest, distinct from cell aging and cell death. Quiescent cells do not proliferate, but may re-enter the cell cycle at any time, given sufficient nutrients and growth conditions. Cells enter quiescence when nutrients are scarce or when growth area is limited. While the ability of a cell to sense and respond to a lack of resources in its environment is a beautifully sophisticated survival mechanism, it seems obvious that these cells couldn’t possibly by serving a purpose in the body as a whole. In fact, for decades, the science community assumed that these cells are simply lying dormant until they have enough nutrients and space to start making a contribution again — proliferating.
Quiescent cells were pushed to the sidelines of scientific investigation for decades due to these assumptions that it is not only a passive state devoid of productivity, but also a defective state in which proliferation has failed to occur. Research funds and efforts were directed toward proliferating cells that serve a purpose in the organism — the cells that actually contribute to the health, growth and vitality of the organism.
In the early 2000s, a few studies drew a correlation between quiescent cell populations and both cancer and aging. A few studies were done to begin characterizing these non-proliferating cells, and between 2006 and 2008, quiescent gene expression profiles were investigated (2) (3). It was expected that these investigations would reveal that quiescent cells have a normal gene expression profile, except that they lack expression of any proteins involved in proliferation. Reality was more complicated than this. There was certainly a gap in the protein expression profile where the proliferation genes would be, but there wasn’t just a lack; there was also a sharp increase in expression of an entirely novel set of genes. This finding alone revealed that quiescence is not solely a passive state. The implication is that these cells have not simply lost the ability to proliferate, but that proliferation has been replaced with something else.
The proteins showing uniquely high abundance in quiescent cell populations were quickly characterized . It was first noted that these proteins are distinct from proteins involved in programmed cell death (apoptosis) or cellular aging (senescence). Not only this, but some of the proteins overly abundant in quiescent cells actually suppress both apoptosis and senescence. Taken together, these results imply that quiescence is not likely to simply be a step along the way to either of these cellular fates. Others of the overly abundant proteins suppress proliferation, suggesting that the cell is safeguarded against re-entering proliferation spontaneously. This is a protected uniquely characterized cell state. It is not simply that proliferation has failed; in quiescent cells, proliferation has been replaced with dormancy.
Now that the quiescent mode of cellular life has gained significant attention from the science community, the importance of these cell populations has become clearer. Quiescent cells are only found in relatively complex organisms. Cells in simpler organisms with shorter lifespans are incapable of quiescence. These organisms, including worms and insects, contain solely proliferating cells during their maturation, and then, in adulthood, all cells become post-mitotic and lose the ability to proliferate further. In more complex animals and humans, lifespans become much longer and to sustain this longevity, cells need to be capable of extensive regeneration. To accommodate this, states of dormancy are necessary; not every single cell needs to proliferate constantly, but a deep pool of “reactivateable” cells is necessary to support a human lifespan. Cellular quiescence provides protection against stress and toxicity as well.
As a third-year PhD student, I looked back over my work in graduate school and saw a landscape of failed attempts. I had nothing to show for my work. No product, no evidence of success. But phases of unproductivity are not uniquely human; they are essential to life at every level of magnification. It’s illogical to conclude that slowed productivity or slumps in output are always the result of human laziness, negligence or apathy. Variation in purpose and multiplicitous meanings of existence are simply attributes of life. So don’t be surprised when this season looks sharply different from the last season. Don’t be surprised if the output slows for a while. Don’t be surprised if you look back over a day, a month, a project or a season and you can find nothing marketable, worthwhile or fruitful that has come out of it. It may be that this time of inactivity and dormancy is storing up within you the stamina you will need for your fullest longevity. It would only be natural for this to be the truth.
1. Yao G (2014). Modelling mammalian cellular quiescence. 4, 20130074.
2. Coller HA, Sang L & Roberts JM (2006). A New Description of Cellular Quiescence. 4, e83.
3. Sang L, Coller HA & Roberts JM (2008). Control of the Reversibility of Cellular Quiescence by the Transcriptional Repressor HES1. 321, 1095–1100.
