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SEL1L-HRD1 ER-Associated Degradation Facilitates Prohormone Convertase 2 Maturation and Glucagon Production in Islet α Cells

Zhu, W.; Pan, L.; Cui, X.; Russo, A. C.; Ray, R.; Pederson, B.; Wei, X.; Lin, L. L.; Hafner, H.; Gregg, B.; Shrestha, N.; Liu, C.; Naji, A.; Arvan, P.; Sandoval, D.; Lindberg, I.; Qi, L.; Reinert, R. B.

2025-03-20 cell biology
10.1101/2025.03.20.644437 bioRxiv
Show abstract

Proteolytic cleavage of proglucagon by prohormone convertase 2 (PC2) is required for islet cells to generate glucagon. However, the regulatory mechanisms underlying this process remain largely unclear. Here, we report that SEL1L-HRD1 endoplasmic reticulum (ER)-associated degradation (ERAD), a highly conserved protein quality control system responsible for clearing misfolded proteins from the ER, plays a key role in glucagon production by regulating turnover of the nascent proform of the PC2 enzyme (proPC2). Using a mouse model with SEL1L deletion in proglucagon-expressing cells, we observed a progressive decline in stimulated glucagon secretion and a reduction in pancreatic glucagon content. Mechanistically, we found that endogenous proPC2 is a substrate of SEL1L-HRD1 ERAD, and that degradation of misfolded proPC2 ensures the maturation of activation-competent proPC2 protein. These findings identify ERAD as a novel regulator of PC2 biology and an essential mechanism for maintaining cell function.

Published in Nature Communications (predicted rank #8) · training set

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