Acute regulation by insulin of phosphatidylinositol-3-kinase, Rad, Glut 4, and lipoprotein lipase mRNA levels in human muscle.

Abstract

We have investigated the acute regulation by insulin of the mRNA levels of nine genes involved in insulin action, in muscle biopsies obtained before and at the end of a 3-h euglycemic hyperinsulinemic clamp. Using reverse transcriptioncompetitive PCR, we have measured the mRNAs encoding the two insulin receptor variants, the insulin receptor substrate-1, the p85 ␣ subunit of phosphatidylinositol-3-kinase, Ras associated to diabetes (Rad), the glucose transporter Glut 4, glycogen synthase, 6-phosphofructo-1-kinase, lipoprotein lipase, and the hormone-sensitive lipase. Insulin infusion induced a significant increase in the mRNA level of Glut 4 ( ϩ 56 Ϯ 13%), Rad ( ϩ 96 Ϯ 25%), the p85 ␣ subunit of phosphatidylinositol-3-kinase ( ϩ 92 Ϯ 18%) and a decrease in the lipoprotein lipase mRNA level ( Ϫ 49 Ϯ 5%), while the abundance of the other mRNAs was unaffected. The relative expression of the two insulin receptor variants was not modified. These results demonstrate an acute coordinated regulation by insulin of the expression of genes coding key proteins involved in its action in human skeletal muscle and suggest that Rad and the p85 ␣ regulatory subunit of phosphatidylinositol-3-kinase can be added to the list of the genes controlled by insulin. ( J. Clin. Invest. 1996. 98:43-49.)

Isoform-specific defects of insulin stimulation of Akt/protein kinase B (PKB) in skeletal muscle cells from type 2 diabetic patients

“…Type 2 diabetic patients were treated with oral hypoglycaemic agents (metformin and sulfonylurea). Participants were submitted to a 3 h hyperinsulinaemic-euglycaemic clamp with an insulin infusion rate of 2 mU kg -1 min -1 as described previously [26,27]. Skeletal muscle (vastus lateralis) biopsies (wet weight about 80 mg) from five control participants and five type 2 diabetic patients were taken under local anaesthesia before and after the clamp [26] to be used for determination of Akt-Ser 473 and -Thr 308 phosphorylation in vivo.…”

The RGK family of GTP-binding proteins: Regulators of voltage-dependent calcium channels and cytoskeleton remodeling

“…Among the most unique features of RGK proteins is their ability to be transcriptionally regulated [3,5,6,11,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] (Table 2). Indeed, Gem/Kir was discovered as a gene upregulated in human T cells after stimulation with mitogens [5] or in BCR-Abl-transformed B cells [11].…”

“…The other RGK subfamily members also demonstrate tissue and molecule-specific transcriptional regulation [3,4,6,20,21,24,25,27,[30][31][32][33][34][35]. Rem is expressed predominantly in cardiac muscle, but also at more modest levels in lung, kidney, and skeletal muscle [3]; Rem2 is highly expressed in the brain and kidney, but also in neuroendocrine tissues [4]; Rad is found in abundance in cardiac and skeletal muscle [6]; while Gem/Kir is found in a diverse set of tissues, including myeloid cells, kidney, liver, and lung [5].…”

“…Rad was initially identified as a gene overexpressed in the skeletal muscle of non-insulin dependent diabetics [6], though subsequent studies in Pima Indians and the Zucker diabetic rat model imply that this effect is not universal [39]. Regulation may result from the hyperinsulinemia associated with the disease [40] as insulin has been shown to increase Rad mRNA levels in muscle [25]. In addition, Rad expression is upregulated in both developing and post-amputation de-differentiating muscle cells in the newt [33].…”

Hormone sensitive lipase expression and adipose tissue metabolism show gender difference in obese subjects after weight loss

“…44 The construction of the competitor molecule, the validation of the assay and the sequences of the primers have been reported. 45 To improve the analysis of the competitive PCR products, the sense primers were 5 0 end labeled with the CY-5 fluorescent probe.…”