Defining the contribution of AMP-activated protein kinase (AMPK) and protein kinase C (PKC) in regulation of glucose uptake by metformin in skeletal muscle cells

Sophie Turban, Clare Stretton, Olivier Drouin, Charlotte J. Green, Maria L. Watson, Alexander Gray, Fiona Ross, Louise Lantier, Benoit Viollet, D.Grahame Hardie, Andre Marette, Harinder S. Hundal (Lead / Corresponding author)

    Research output: Contribution to journalArticle

    61 Citations (Scopus)

    Abstract

    The importance of AMP-activated protein kinase (AMPK) and protein kinase C (PKC) as effectors of metformin (Met) action on glucose uptake (GU) in skeletal muscle cells was investigated. GUin L6 myotubes was stimulated 2-fold following 16 h of Met treatment and acutely enhanced by insulin in an additive fashion. Insulin-stimulatedGUwas sensitive to PI3K inhibition, whereas that induced by Met was not. Met and its related biguanide, phenformin, stimulated AMPK activation/phosphorylation to a level comparable with that induced by the AMPK activator, 5-amino-1-ß-D-ribofuranosyl-imidazole-4-carboxamide (AICAR). However, the increase in GU elicited by AICAR was significantly lower than that induced by either biguanide. Expression of a constitutively active AMPK mimicked the effects of AICAR on GU, whereas a dominant interferingAMPK or shRNA silencing of AMPK prevented AICAR-stimulated GU and Met-induced AMPK signaling but only repressed biguanide- stimulated GU by ~20%. Consistent with this, analysis of GU in muscle cells from a1 /a2 AMPK-deficient mice revealed a significant retention of Met-stimulated GU, being reduced by ~35% compared with that of wild type cells. Atypical PKCs (aPKCs) have been implicated in Met-stimulated GU, and in line with this, Met and phenformin induced activation/phosphorylation of aPKC in L6 myotubes. However, although cellular depletion of aPKC (>90%) led to loss in biguanide-induced aPKC phosphorylation, it had no effect on Met-stimulated GU, whereas inhibitors targeting novel/conventional PKCs caused a significant reduction in biguanide-induced GU. Our findings indicate that although Met activates AMPK, a significant component of Met-stimulated GU in muscle cells is mediated via an AMPK-independent mechanism that involves novel/conventional PKCs.
    Original languageEnglish
    Pages (from-to)20088-20099
    Number of pages12
    JournalJournal of Biological Chemistry
    Volume287
    Issue number24
    DOIs
    Publication statusPublished - 8 Jun 2012

    Fingerprint Dive into the research topics of 'Defining the contribution of AMP-activated protein kinase (AMPK) and protein kinase C (PKC) in regulation of glucose uptake by metformin in skeletal muscle cells'. Together they form a unique fingerprint.

  • Cite this