title: Suppression of islet homeostasis protein thwarts diabetes mellitus progression.
abstract: During progression to type 1 diabetes, insulin-producing β-cells are lost through an autoimmune attack resulting in unrestrained glucagon expression and secretion, activation of glycogenolysis, and escalating hyperglycemia. We recently identified a protein, designated islet homeostasis protein (IHoP), which specifically co-localizes within glucagon-positive α-cells and is overexpressed in the islets of both post-onset non-obese diabetic (NOD) mice and type 1 diabetes patients. Here we report that in the αTC1.9 mouse α-cell line, IHoP was released in response to high-glucose challenge and was found to regulate secretion of glucagon. We also show that in NOD mice with diabetes, major histocompatibility complex class II was upregulated in islets. In addition hyperglycemia was modulated in NOD mice via suppression of IHoP utilizing small interfering RNA (IHoP-siRNA) constructs/approaches. Suppression of IHoP in the pre-diabetes setting maintained normoglycemia, glyconeolysis, and fostered β-cell restoration in NOD mice 35 weeks post treatment. Furthermore, we performed adoptive transfer experiments using splenocytes from IHoP-siRNA-treated NOD/ShiLtJ mice, which thwarted the development of hyperglycemia and the extent of insulitis seen in recipient mice. Last, IHoP can be detected in the serum of human type 1 diabetes patients and could potentially serve as an early novel biomarker for type 1 diabetes in patients.
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Seh-Hoon
authors.initials: SH
authors.lastname: Oh
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Marda L
authors.initials: ML
authors.lastname: Jorgensen
authors.affiliation: Department of Pathology, Diabetes Institute, Colleges of Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Clive H
authors.initials: CH
authors.lastname: Wasserfall
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Altin
authors.initials: A
authors.lastname: Gjymishka
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Bryon E
authors.initials: BE
authors.lastname: Petersen
mesh_terms: D000818:Animals; D002460:Cell Line; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D005260:Female; D005934:Glucagon / Q000032:analysis / Q000378:metabolism; D006681:HLA-D Antigens / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism; D007515:Islets of Langerhans / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D011506:Proteins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D006681:HLA-D Antigens; D018398:Homeodomain Proteins; D011506:Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D005934:Glucagon