Monomeric G-protein, Rhes, is not an imidazoline-regulated protein in pancreatic beta-cells.
The monomeric G-protein, Rhes, is a candidate imidazoline-regulated molecule involved in mediating the insulin secretory response to efaroxan [S.L. Chan, L.K. Monks, H. Gao, P. Deaville, N.G. Morgan, Identification of the monomeric G-protein, Rhes, as an efaroxan-regulated protein in the pancreatic beta-cell, Br. J. Pharmacol. 136 (1) (2002) 31-36]. This suggestion was based on observations regarding changes in Rhes mRNA expression in rat islets and pancreatic beta-cells after prolonged culture with efaroxan, leading to desensitization of the insulin response to the compound. To verify this report, we have evaluated the effects of the imidazoline compounds efaroxan and BL11282 on Rhes mRNA expression in isolated rat pancreatic islets maintained in conditions identical to those used by Chan et al. The results demonstrate that desensitization of the insulin response to efaroxan, or to another imidazoline, BL11282, does not change Rhes mRNA expression levels. Transfection of MIN6 cells with plasmids containing Rhes or Rhes-antisense also does not alter efaroxan- or BL11282-induced insulin secretion. Together, these data do not support the hypothesis that Rhes is an imidazoline-regulated protein.
Sharoyko
Vladimir V
VV
The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, Solna, SE-17176 Stockholm, Sweden.
Zaitseva
Irina I
II
Varsanyi
Mark
M
Portwood
Neil
N
Leibiger
Barbara
B
Leibiger
Ingo
I
Berggren
Per-Olof
PO
Efendić
Suad
S
Zaitsev
Sergei V
SV
D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D048288:Imidazolines / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar
D048288:Imidazolines; D007328:Insulin; D012333:RNA, Messenger; D019204:GTP-Binding Proteins; C442475:Rasd2 protein, rat; D020559:Monomeric GTP-Binding Proteins