Hyperthermia with mild electrical stimulation protects pancreatic ?-cells from cell stresses and apoptosis.

ABSTRACT: Induction of heat shock protein (HSP) 72 improves metabolic profiles in diabetic model mice. However, its effect on pancreatic ?-cells is not known. The current study investigated whether HSP72 induction can reduce ?-cell stress signaling and apoptosis and preserve ?-cell mass. MIN6 cells and db/db mice were sham-treated or treated with heat shock (HS) and mild electrical stimulation (MES) (HS+MES) to induce HSP72. Several cellular markers, metabolic parameters, and ?-cell mass were evaluated. HS+MES treatment or HSP72 overexpression increased HSP72 protein levels and decreased tumor necrosis factor (TNF)-?-induced Jun NH(2)-terminal kinase (JNK) phosphorylation, endoplasmic reticulum (ER) stress, and proapoptotic signal in MIN6 cells. In db/db mice, HS+MES treatment for 12 weeks significantly improved insulin sensitivity and glucose homeostasis. Upon glucose challenge, a significant increase in insulin secretion was observed in vivo. Compared with sham treatment, levels of HSP72, insulin, pancreatic duodenal homeobox-1, GLUT2, and insulin receptor substrate-2 were upregulated in the pancreatic islets of HS+MES-treated mice, whereas JNK phosphorylation, nuclear translocation of forkhead box class O-1, and nuclear factor-?B p65 were reduced. Apoptotic signals, ER stress, and oxidative stress markers were attenuated. Thus, HSP72 induction by HS+MES treatment protects ?-cells from apoptosis by attenuating JNK activation and cell stresses. HS+MES combination therapy may preserve pancreatic ?-cell volume to ameliorate glucose homeostasis in diabetes.

SUBMITTER: Kondo T 

PROVIDER: S-EPMC3314363 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature