Leptin stimulates insulin secretion and synthesis in HIT-T 15 cells.
Leptin, an ob gene product, corrects hyperinsulinemia in ob/ob mice. The leptin receptor may exist in pancreatic islets. The present studies were undertaken to determine the direct effect of 1-100 ng/ml recombinant leptin on insulin secretion and synthesis in HIT-T 15 cells by using static culture system. The addition of recombinant leptin significantly increased insulin secretion for 20 min at the highest concentration (100 ng/ml). The addition of recombinant leptin dose-dependently increased insulin secretion for 24 h in the 7 mM glucose-containing F-12 K medium. The incubation with recombinant leptin for 24 h increased preproinsulin mRNA expression, assessed with reverse transcription-polymerase chain reaction (RT-PCR) method. It was furthermore demonstrated that HIT-T 15 cells possessed the specific binding site for [125I]-labeled leptin. The present study demonstrated the existence of the leptin-specific binding sites that mediate its stimulatory effect on insulin secretion and synthesis in HIT-T 15 cells.
Shimizu
H
H
First Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Japan.
Ohtani
K
K
Tsuchiya
T
T
Takahashi
H
H
Uehara
Y
Y
Sato
N
N
Mori
M
M
D000199:Actins / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D007328:Insulin / Q000096:biosynthesis / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D020738:Leptin; D008647:Mesocricetus; D011384:Proinsulin / Q000096:biosynthesis / Q000235:genetics; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D011506:Proteins / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology
D000199:Actins; D002352:Carrier Proteins; D007328:Insulin; D020738:Leptin; D011498:Protein Precursors; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D011994:Recombinant Proteins; C013737:preproinsulin; D011384:Proinsulin