Preservation of insulin mRNA levels and insulin secretion in HIT cells by avoidance of chronic exposure to high glucose concentrations.
Glucose toxicity of the pancreatic beta cell is considered to play a secondary role in the pathogenesis of type II diabetes mellitus. To gain insights into possible mechanisms of action of glucose toxicity, we designed studies to assess whether the loss of insulin secretion associated with serial passages of HIT-T15 cells might be caused by chronic exposure to high glucose levels since these cells are routinely cultured in media containing supramaximal stimulatory concentrations of glucose. We found that late passages of HIT cells serially cultured in media containing 11.1 mM glucose lost insulin responsivity and had greatly diminished levels of insulin content and insulin mRNA. In marked contrast, late passages of HIT cells cultured serially in media containing 0.8 mM glucose retained insulin mRNA, insulin content, and insulin responsivity to glucose in static incubations and during perifusion with glucose. No insulin gene mutation or alteration of levels of GLUT-2 were found in late passages of HIT cells cultured with media containing 11.1 mM glucose. These data uniquely indicate that loss of beta cell function in HIT cells passed serially under high glucose conditions is caused by loss of insulin mRNA, insulin content, and insulin secretion and is preventable by culturing HIT cells under low glucose conditions. This strongly suggests potential genetic mechanisms of action for glucose toxicity of beta cells.
Robertson
R P
RP
Diabetes Center, University of Minnesota Medical School, Minneapolis 55455.
Zhang
H J
HJ
Pyzdrowski
K L
KL
Walseth
T F
TF
D000818:Animals; D002455:Cell Division; D002460:Cell Line; D006224:Cricetinae; D003470:Culture Media; D015870:Gene Expression; D005796:Genes; D005947:Glucose / Q000633:toxicity*; D066298:In Vitro Techniques; D007328:Insulin / Q000235:genetics* / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D008647:Mesocricetus; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics
D003470:Culture Media; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D005947:Glucose