Effects of adenoviral gene transfer of wild-type, constitutively active, and kinase-defective protein kinase C-λ on insulin-stimulated glucose transport in L6 myotubes
G Bandyopadhyay, Y Kanoh, MP Sajan… - …, 2000 - academic.oup.com
G Bandyopadhyay, Y Kanoh, MP Sajan, ML Standaert, RV Farese
Endocrinology, 2000•academic.oup.comWe used adenoviral gene transfer methods to evaluate the role of atypical protein kinase Cs
(PKCs) during insulin stimulation of glucose transport in L6 myotubes. Expression of wild-
type PKC-λ potentiated maximal and half-maximal effects of insulin on 2-deoxyglucose
uptake, but did not alter basal uptake. Expression of constitutively active PKC-λ enhanced
basal 2-deoxyglucose uptake to virtually the same extent as that observed during insulin
treatment. In contrast, expression of kinase-defective PKC-λ completely blocked insulin …
(PKCs) during insulin stimulation of glucose transport in L6 myotubes. Expression of wild-
type PKC-λ potentiated maximal and half-maximal effects of insulin on 2-deoxyglucose
uptake, but did not alter basal uptake. Expression of constitutively active PKC-λ enhanced
basal 2-deoxyglucose uptake to virtually the same extent as that observed during insulin
treatment. In contrast, expression of kinase-defective PKC-λ completely blocked insulin …
Abstract
We used adenoviral gene transfer methods to evaluate the role of atypical protein kinase Cs (PKCs) during insulin stimulation of glucose transport in L6 myotubes. Expression of wild-type PKC-λ potentiated maximal and half-maximal effects of insulin on 2-deoxyglucose uptake, but did not alter basal uptake. Expression of constitutively active PKC-λ enhanced basal 2-deoxyglucose uptake to virtually the same extent as that observed during insulin treatment. In contrast, expression of kinase-defective PKC-λ completely blocked insulin-stimulated, but not basal, 2-deoxyglucose uptake. Similar to alterations in glucose transport, constitutively active PKC-λ mimicked, and kinase-defective PKC-λ completely inhibited, insulin effects on GLUT4 glucose transporter translocation to the plasma membrane. Expression of kinase-defective PKC-λ, in addition to inhibition of atypical PKC enzyme activity, was attended by paradoxical increases in GLUT4 and GLUT1 glucose transporter levels and insulin-stimulated protein kinase B enzyme activity. Our findings suggest that in L6 myotubes, 1) atypical PKCs are required and sufficient for insulin-stimulated GLUT4 translocation and glucose transport; and 2) activation of protein kinase B in the absence of activation of atypical PKCs is insufficient for insulin-induced activation of glucose transport.
Oxford University Press