Stress response roles in driving meiotic cellular remodeling
Through meiotic differentiation, in the absence of dynamic external stimuli, we have observed timed induction of prominent stress pathway factors . Many of these pathways include post-translational regulation, suggesting that these measurements underestimate their dynamic control. Nonetheless, the striking and stereotypical regulation of stress programs in meiosis suggests that while harsh exogenous treatment including heat and drugs may have enabled their discovery, categorization of such pathways as 'stress-responsive' may not reflect their sole or even major physiological role.
The DNA damage response is a case in which a conserved and dedicated role in meiotic differentiation is clear. In fact, studies of meiotic recombination have revealed general principles of DNA repair. We propose that this case reflects a broad theme. For instance, while central components of the Unfolded Protein Response (UPR) are conserved from yeast to human,they are dispensable for growth in yeast. Thus, study of the yeast UPR has relied on non-physiological experimentation, including the use of inhibitors of ER (endoplasmic reticulum) folding such as dithiothreitol (DTT). Drug-based studies have yielded significant insight into UPR function, but meiotic UPR induction provides the first physiological yeast model of timed induction akin to that seen in differentiating mammalian cells. This allows us access to previously inaccessible questions about natural UPR signaling, while also allowing an opportunity to learn about the role of ER remodeling in meiosis.