title: Protein kinase C-lambda knockout in embryonic stem cells and adipocytes impairs insulin-stimulated glucose transport.
abstract: Atypical protein kinase C (aPKC) isoforms have been suggested to mediate insulin effects on glucose transport in adipocytes and other cells. To more rigorously test this hypothesis, we generated mouse embryonic stem (ES) cells and ES-derived adipocytes in which both aPKC-lambda alleles were knocked out by recombinant methods. Insulin activated PKC-lambda and stimulated glucose transport in wild-type (WT) PKC-lambda(+/+), but not in knockout PKC-lambda(-/-), ES cells. However, insulin-stimulated glucose transport was rescued by expression of WT PKC-lambda in PKC-lambda(-/-) ES cells. Surprisingly, insulin-induced increases in both PKC-lambda activity and glucose transport were dependent on activation of proline-rich tyrosine protein kinase 2, the ERK pathway, and phospholipase D (PLD) but were independent of phosphatidylinositol 3-kinase (PI3K) in PKC-lambda(+/+) ES cells. Interestingly, this dependency was completely reversed after differentiation of ES cells to adipocytes, i.e. insulin effects on PKC-lambda and glucose transport were dependent on PI3K, rather than proline-rich tyrosine protein kinase 2/ERK/PLD. As in ES cells, insulin effects on glucose transport were absent in PKC-lambda(-/-) adipocytes but were rescued by expression of WT PKC-lambda in these adipocytes. Our findings suggest that insulin activates aPKCs and glucose transport in ES cells by a newly recognized PI3K-independent ERK/PLD-dependent pathway and provide a compelling line of evidence suggesting that aPKCs are required for insulin-stimulated glucose transport, regardless of whether aPKCs are activated by PI3K-dependent or PI3K-independent mechanisms.
authors: James A Haley Veterans Hospital and University of South Florida College of Medicine, Tampa, 33612, USA.
authors: Gautam
authors: G
authors: Bandyopadhyay
authors: Mary L
authors: ML
authors: Standaert
authors: Mini P
authors: MP
authors: Sajan
authors: Yoshinori
authors: Y
authors: Kanoh
authors: Atsushi
authors: A
authors: Miura
authors: Uschi
authors: U
authors: Braun
authors: Friederike
authors: F
authors: Kruse
authors: Michael
authors: M
authors: Leitges
authors: Robert V
authors: RV
authors: Farese
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004622:Embryo, Mammalian / Q000166:cytology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051418:Focal Adhesion Kinase 2; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D007527:Isoenzymes; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000187:drug effects / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism*; D000099293:Protein Kinase C-lambda
chemical_list: D003847:Deoxyglucose; D004791:Enzyme Inhibitors; D051418:Focal Adhesion Kinase 2; D005947:Glucose; D051272:Glucose Transporter Type 1; D007328:Insulin; D007527:Isoenzymes; D020928:Mitogen-Activated Protein Kinases; D009004:Monosaccharide Transport Proteins; D019869:Phosphatidylinositol 3-Kinases; D010739:Phospholipase D; D011493:Protein Kinase C; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D000099293:Protein Kinase C-lambda