Dominant-negative α-subunit of farnesyl- and geranyltransferase inhibits glucose-stimulated, but not KCI-stimulated, insulin secretion in INS 832/13 cells

被引:47
作者
Veluthakal, Rajakrishnan
Kaur, Hitchintan
Goalstone, Marc
Kowluru, Anjaneyulu
机构
[1] Wayne State Univ, Eugene Applebaum Coll Pharm & Hlth Sci, Dept Pharmaceut Sci, Detroit, MI 48201 USA
[2] John D Dingell Vet Affairs Med Ctr, Beta Cell Biochem Res Lab, Detroit, MI USA
[3] Denver VA Med Ctr, Res Serv, Denver, CO USA
[4] Univ Colorado, Hlth Sci Ctr, Dept Med, Denver, CO 80202 USA
关键词
D O I
10.2337/db06-0668
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
The majority of small G-proteins undergo posttranslational modifications (e.g., isoprenylation) at their C-terminal cysteine residues. Such modifications increase their hydrophobicity, culminating in translocation of the modified proteins to their relevant membranous sites for interaction with their respective effectors. Previously, we reported glucose-dependent activation and membrane association of Rac1 in INS 832/13 cells. We also demonstrated modulatory roles for Rac1/GDP dissociation inhibitor in glucose-stimulated insulin secretion (GSIS) in INS 832/13 cells, further affirming roles for Racl in GSIS. Herein, we demonstrate that geranylgeranyltransferase inhibitor-2147 (GGTI-2147), an inhibitor of protein prenylation, markedly increased cytosolic accumulation of Racl and elicited significant inhibition of GSIS from INS 832/13 cells. In the current study, we also examined the localization of protein prenyltransferases (PPTases) and regulation of GSIS by PPTases in INS 832/13 cells. Western blot analyses indicated that the regulatory alpha-subunit and the structural R-subunit of PPTase holoenzyme are predominantly cytosolic in their distribution. Overexpression of an inactive mutant of the regulatory alpha-subunit of PPTase markedly attenuated glucose- but not KCI-induced insulin secretion from INS 832/13 cells. Together, our findings provide the first evidence for the regulation of GSIS by PPTase in INS 832/13 cells. Furthermore, they support our original hypothesis that prenylation of specific G-proteins may be necessary for GSIS. Diabetes
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页码:204 / 210
页数:7
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