Deteriorated high-fat diet-induced diabetes caused by pancreatic β-cell-specific overexpression of Reg3β gene in mice.
Reg family proteins have long been implicated in islet β-cell proliferation, survival, and regeneration. In our previous study, we reported that Reg3β overexpression did not increase islet growth but prevented streptozotocin-induced islet damage by inducing specific genes. In order to explore its role in type 2 diabetes (T2D), we established high-fat diet (HFD)-induced obesity and diabetes in RIP-I/Reg3β mice. Glucose and insulin tolerance tests, immunofluorescence for insulin, eIF2α, and GLUT2 in islets, Western blots on phosphorylated AMPKα and hepatic histology were performed. Both RIP-I/Reg3β and wild-type mice gained weight rapidly and became hyperglycemic after 10 weeks on the HFD. However, the transgenic mice exhibited more significant acceleration in blood glucose levels, further deterioration of glucose intolerance and insulin resistance, and a lower intensity of insulin staining. Immunofluorescence revealed similar magnitude of islet compensation to a wild-type HFD. The normal GLUT2 distribution in the transgenic β-cells was disrupted and the staining was obviously diminished on the cell membrane. HFD feeding also caused a further decrease in the level of AMPKα phosphorylation in the transgenic islets. Our results suggest that unlike its protective effect against T1D, overexpressed Reg3β was unable to protect the β-cells against HFD-induced damage.
Fraser Laboratories for Diabetes Research, Department of Medicine, RI-McGill University Health Centre, Room E02.7220, 1001 Décarie Blvd, Montreal, QC, H4A 3J1, Canada.
Xiaoquan
X
Xiong
Fraser Laboratories for Diabetes Research, Department of Medicine, RI-McGill University Health Centre, Room E02.7220, 1001 Décarie Blvd, Montreal, QC, H4A 3J1, Canada.
Qing
Q
Li
Department of Endocrinology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
Wei
W
Cui
Department of Pathology, RI-McGill University Health Centre, Room E04.1820, 1001 Decarie Boulevard, Montreal, QC, H4A 3J1, Canada. zu-hua.gao@mcgill.ca.
Zu-Hua
ZH
Gao
Fraser Laboratories for Diabetes Research, Department of Medicine, RI-McGill University Health Centre, Room E02.7220, 1001 Décarie Blvd, Montreal, QC, H4A 3J1, Canada. jun-li.liu@mcgill.ca.|Montreal Diabetes Research Centre, Montreal, Canada. jun-li.liu@mcgill.ca.
Jun-Li
JL
Liu
D000263:Adenylate Kinase / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000235:genetics / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism*; D059305:Diet, High-Fat; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D018149:Glucose Intolerance / Q000235:genetics / Q000378:metabolism; D051273:Glucose Transporter Type 2 / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D008297:Male; D051379:Mice; D000073718:Pancreatitis-Associated Proteins; D010766:Phosphorylation; D011506:Proteins / Q000235:genetics / Q000378:metabolism*
D001786:Blood Glucose; D015852:Eukaryotic Initiation Factor-2; D051273:Glucose Transporter Type 2; D007328:Insulin; D000073718:Pancreatitis-Associated Proteins; D011506:Proteins; C490253:Reg3b protein, mouse; D000263:Adenylate Kinase
AMPKα; Aging; GLUT2; Hepatic steatosis; Insulin resistance; eIF2α