Investigating the role of a novel RNA binding protein during dauer in C. elegans

MicroRNAs (miRNAs) are a conserved class of small, endogenous noncoding RNAs that regulate gene expression post-transcriptionally. They play critical roles in essential biological processes, including animal growth and development. Dysregulation of the miRNA pathway has been implicated in the pathogenesis of various human diseases. miRNAs exert their function through the miRNA-induced silencing complex (miRISC), which comprises the Argonaute protein (ALG-1 in C. elegans) and other protein cofactors. The composition of miRISC—and thus its ability to degrade mRNA targets—varies based on tissue type and physiological conditions. For example, somatic and germline miRISC recruit distinct cofactors, leading to different outcomes for target mRNAs. miRISC composition also shifts dynamically in response to environmental stress or aging. Under adverse environmental conditions, C. elegans enters an alternative, stress-resistant developmental stage known as dauer. A key unanswered question in the field is how the miRNA pathway rapidly transitions from regulating pro-developmental gene expression to stress-adaptive gene expression during this stage. Our preliminary studies reveal two novel protein interactors of miRISC during dauer: the conserved RNA-binding protein UNK-1 (Unkempt) and its binding partner, CRI-1 (Headcase). I hypothesize that UNK-1 and CRI-1 are critical for stress adaptation in dauer by interacting with miRISC to promote the degradation of pro-developmental gene targets. I will test this hypothesis in three specific aims: In Aim 1, I will characterize the interactions between UNK-1, CRI-1, and miRISC, and determine whether they are mediated by direct protein-protein interactions or indirectly through a shared set of mRNA targets. In Aim 2, I will identify the mRNA targets of UNK-1 and assess their overlap with miRISC targets. Preliminary data indicate that UNK-1 expression is highly upregulated during the dauer stage. In Aim 3, I will investigate the regulation of UNK-1 and CRI-1 expression during dauer and evaluate their roles in stress adaptation. The conservation of UNK-1 and CRI-1 across species, including humans, suggests that their role in miRISC regulation during stress may be evolutionarily preserved. This work could provide insights into fundamental processes such as metabolism, aging, and cancer, offering broader implications for understanding stress adaptation in complex organisms.