Mutated insulin receptor Val996 reduces insulin-dependent generation of inositol glycan and diacylglycerol.
We evaluated whether insulin-receptor tyrosine kinase activity is required for activation of PDH, insulin-induced hydrolysis of PIG and generation of IG and 1,2-DAG. For the analysis, we used stable-transfected CHO cell lines expressing wild-type human insulin receptor (CHO-wt cells) or the mutant receptor (Val996) that lacks tyrosine kinase activity (CHO-mut cells) (1,2). Insulin stimulated PDH activity in three CHO cell lines in a dose-dependent manner. Half-maximal concentrations of insulin to activate PDH was 7 x 10(-11) M in the CHO-wt cells, 10(-9) M in the parental cells, and 8 x 10(-9) M in the CHO-mut cells. Insulin stimulated hydrolysis of PIG and generation of IG and DAG in three CHO cell lines in a dose-dependent manner. Half-maximal concentrations of insulin to induce generation of IG was 8 x 10(-11) M in the CHO-wt cells, 10(-9) M in the parental CHO cells, and 10(-8) M in the CHO-mut cells. ED50 for the stimulation of DAG generation was 7 x 10(-11) M in the CHO-wt cells, 10(-9) M in the parental cells, and 10(-8) M in the CHO-mut cells. It is concluded that insulin-dependent PDH activation, PIG hydrolysis, and IG and DAG generation are mediated by the wild-type but not by the mutated insulin receptor of Val996. This study suggests that tyrosine kinase activity of the insulin receptor might be a prerequisite for insulin-stimulated generation of IG and DAG.
Suzuki
S
S
Third Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Taneda
Y
Y
Hirai
S
S
Yamamoto-Honda
R
R
Toyota
T
T
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004075:Diglycerides / Q000096:biosynthesis*; D017261:Glycosylphosphatidylinositols; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D010716:Phosphatidylinositols / Q000096:biosynthesis*; D011134:Polysaccharides / Q000096:biosynthesis*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014633:Valine
D004075:Diglycerides; D017261:Glycosylphosphatidylinositols; D007328:Insulin; D010716:Phosphatidylinositols; D011134:Polysaccharides; D011768:Pyruvate Dehydrogenase Complex; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D014633:Valine