CHARACTERIZATION OF THE MITOCHONDIRAL UPR-REGULATED SERPIN SRP-1

The mitochondrial unfolded protein response (UPRmt) is a regulatory stress response that is involved in the protection of mitochondrial function. Cells activate this transcriptional response to promote cell survival and the recovery of the mitochondrial functionality. In the model organism Caenorhabditis elegans, the UPRmt is regulated by an essential transcription factor known as ATFS-1. When mitochondrial function is compromised, ATFS-1 regulates the expression of a variety of genes, including srp-1, which encodes an uncharacterized serpin. Serpins are part of a larger superfamily with classical roles in blocking protease enzymes, but their function during mitochondrial stress is unknown. We sought to examine the role of this UPRmt-regulated serpin during mitochondrial stress. We find that srp-1 gene knockdown by RNA interference enhances UPRmt activation during mitochondrial stress. Interestingly, srp-1 displays a refined expression in a subset of four small interfacial epithelial cells. Furthermore, srp-1 protein appears to localize to the endoplasmic reticulum suggesting inter-organellar stress crosstalk.