title: Uncoupling proteostasis and development in vitro with a small molecule inhibitor of the pancreatic endoplasmic reticulum kinase, PERK.
abstract: Loss-of-function mutations in EIF2AK3, encoding the pancreatic endoplasmic reticulum (ER) kinase, PERK, are associated with dysfunction of the endocrine pancreas and diabetes. However, to date it has not been possible to uncouple the long term developmental effects of PERK deficiency from sensitization to physiological levels of ER unfolded protein stress upon interruption of PERK modulation of protein synthesis rates. Here, we report that a selective PERK inhibitor acutely deregulates protein synthesis in freshly isolated islets of Langerhans, across a range of glucose concentrations. Acute loss of the PERK-mediated strand of the unfolded protein response leads to rapid accumulation of misfolded pro-insulin in cultured beta cells and is associated with a kinetic defect in pro-insulin processing. These in vitro observations uncouple the latent role of PERK in beta cell development from the regulation of unfolded protein flux through the ER and attest to the importance of the latter in beta cell proteostasis.
authors.affiliation: Metabolic Research Laboratories, University of Cambridge, and National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, United Kingdom. hph23@medschl.cam.ac.uk
authors.forename: Heather P
authors.initials: HP
authors.lastname: Harding
authors.forename: Alisa F
authors.initials: AF
authors.lastname: Zyryanova
authors.forename: David
authors.initials: D
authors.lastname: Ron
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D007328:Insulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D014176:Protein Biosynthesis / Q000187:drug effects; D017510:Protein Folding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051381:Rats; D056811:Unfolded Protein Response / Q000187:drug effects; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D015852:Eukaryotic Initiation Factor-2; D005947:Glucose; D007328:Insulin; D047428:Protein Kinase Inhibitors; D019892:eIF-2 Kinase