Protein Kinase C-λ Knockout in Embryonic Stem Cells and Adipocytes Impairs Insulin-Stimulated Glucose Transport

Bandyopadhyay, Gautam; Standaert, Mary L.; Sajan, Mini P.; Kanoh, Yoshinori; Miura, Asako; Braun, Ursula; Kruse, Friederike; Leitges, Michael; Farese, Robert V.

doi:10.1210/me.2003-0087

Cited by 51 publications

(50 citation statements)

References 17 publications

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“…This screen identified PKCζ as a true positive and thus a novel interactor with munc18c. This association merited investigation because PKCζ is one of the key enzymes regulated by insulin and has been shown to affect glucose transport through an as yet unidentified mechanism [1,2,28,29]. The interaction between munc18c and PKCζ was confirmed by GST pull-downs.…”

Section: Discussionmentioning

confidence: 96%

“…This is achieved by activation of a signalling cascade and the trafficking of a vesicle containing the glucose transporter GLUT4 to the plasma membrane. Several kinases involved in insulin-stimulated glucose transport have been discovered, namely, protein kinase (PK) Cζ/λ [1,2] and PKB [3,4]. CAP-Cbl has also been implicated in insulin-stimulated glucose transport [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Protein kinase-ζ interacts with munc18c: role in GLUT4 trafficking

2005

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Aims/hypothesis: Insulin-stimulated glucose transport requires a signalling cascade through kinases protein kinase (PK) Cζ/λ and PKB that leads to movement of GLUT4 vesicles to the plasma membrane. The aim of this study was to identify missing links between the upstream insulin-regulated kinases and the GLUT4 vesicle trafficking system. Materials and methods: A yeast twohybrid screen was conducted, using as bait full-length mouse munc18c, a protein known to be part of the GLUT4 vesicle trafficking machinery. Results: The yeast twohybrid screen identified PKCζ as a novel interactor with munc18c. Glutathione S transferase (GST) pull-downs with GST-tagged munc18c constructs confirmed the interaction, mapped a key region of munc18c that binds PKCζ to residues 295-338 and showed that the N-terminal region of PKCζ was required for the interaction. Endogenous munc18c was shown to associate with endogenous PKCζ in vivo in various cell types. Importantly, insulin stimulation increased the association by approximately three-fold. Moreover, disruption of PKCζ binding to munc18c by deletion of residues 295-338 of munc18c or deletion of the N-terminal region of PKCζ markedly inhibited the ability of insulin to stimulate glucose uptake or GLUT4 translocation. Conclusions/interpretation: We have identified a physiological interaction between munc18c and PKCζ that is insulin-regulated. This establishes a link between a kinase (PKCζ) involved in the insulin signalling cascade and a known component of the GLUT4 vesicle trafficking pathway (munc18c). The results indicate that PKCζ regulates munc18c and suggest a model whereby insulin triggers the docking of PKCζ to munc18c, resulting in enhanced GLUT4 translocation to the plasma membrane.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Protein kinase-ζ interacts with munc18c: role in GLUT4 trafficking

2005

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“…Here, we report on a muscle-specific PKC-λ KO created by breeding mice harboring Cre recombinase transgene controlled by a muscle creatine kinase (MCK) promotor/enhancer with mice carrying a targeted PKC-λ allele with loxP sites flanking an essential exon located at nucleotides 110-233; details of the floxed PKC-λ construct were described previously (22). In these mice, we directly tested the hypothesis that aPKC is required for glucose transport effects of insulin; moreover, we examined the metabolic consequences of defects in aPKC availability/activation and glucose transport occurring specifically in muscle.…”

Section: Introductionmentioning

confidence: 99%

Muscle-specific knockout of PKC-λ impairs glucose transport and induces metabolic and diabetic syndromes

Farese

Sajan²,

Yang³

et al. 2007

J. Clin. Invest.

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143

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Obesity, the metabolic syndrome, and type 2 diabetes mellitus (T2DM) are major global health problems. Insulin resistance is frequently present in these disorders, but the causes and effects of such resistance are unknown. Here, we generated mice with muscle-specific knockout of the major murine atypical PKC (aPKC), PKC-λ, a postulated mediator for insulin-stimulated glucose transport. Glucose transport and translocation of glucose transporter 4 (GLUT4) to the plasma membrane were diminished in muscles of both homozygous and heterozygous PKC-λ knockout mice and were accompanied by systemic insulin resistance; impaired glucose tolerance or diabetes; islet β cell hyperplasia; abdominal adiposity; hepatosteatosis; elevated serum triglycerides, FFAs, and LDL-cholesterol; and diminished HDL-cholesterol. In contrast to the defective activation of muscle aPKC, insulin signaling and actions were intact in muscle, liver, and adipocytes. These findings demonstrate the importance of aPKC in insulin-stimulated glucose transport in muscles of intact mice and show that insulin resistance and resultant hyperinsulinemia owing to a specific defect in muscle aPKC is sufficient to induce abdominal obesity and other lipid abnormalities of the metabolic syndrome and T2DM. These findings are particularly relevant because humans who have obesity, impaired glucose tolerance, and T2DM reportedly have defective activation and/or diminished levels of muscle aPKC.

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“…Second, genetic disruption of the PKCζ and PKCι/λ genes has very different effects on embryonic development in the mouse. Knock out of PKCι/λ is embryonic lethal (30), whereas knock out of PKCζ results in viable mice that develop essentially normally, exhibiting only subtle immunological deficiencies (31,32). Third, PKCζ and PKCι/λ preferentially couple to distinct downstream signaling pathways.…”

Section: Introductionmentioning

confidence: 99%

Protein kinase Cι: Human oncogene, prognostic marker and therapeutic target

Fields

Regala

2007

Pharmacological Research

112

113

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The Protein kinase C (PKC) family of serine/threonine kinases has been the subject of intensive study in the field of cancer since their initial discovery as major cellular receptors for the tumor promoting phorbol esters nearly thirty years ago. However, despite these efforts, the search for a direct genetic link between members of the PKC family and human cancer has yielded only circumstantial evidence that any PKC isozyme is a true cancer gene. This situation changed in the past year with the discovery that atypical protein kinase C iota (PKCι) is a bonafide human oncogene. PKCι is required for the transformed growth of human cancer cells and the PKCι gene is the target of tumor-specific gene amplification in multiple forms of human cancer. PKCι participates in multiple aspects of the transformed phenotype of human cancer cells including transformed growth, invasion and survival. Herein, we review pertinent aspects of atypical PKC structure, function and regulation that relate to the role of these enzymes in oncogenesis. We discuss the evidence that PKCι is a human oncogene, review mechanisms controlling PKCι expression in human cancers, and describe the molecular details of PKCι-mediated oncogenic signaling. We conclude with a discussion of how oncogenic PKCι signaling has been successfully targeted to identify a novel, mechanism-based therapeutic drug currently entering clinical trials for treatment of human lung cancer. Throughout, we identify key unanswered questions and exciting future avenues of investigation regarding this important oncogenic molecule.

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Protein Kinase C-λ Knockout in Embryonic Stem Cells and Adipocytes Impairs Insulin-Stimulated Glucose Transport

Cited by 51 publications

References 17 publications

Protein kinase-ζ interacts with munc18c: role in GLUT4 trafficking

Protein kinase-ζ interacts with munc18c: role in GLUT4 trafficking

Muscle-specific knockout of PKC-λ impairs glucose transport and induces metabolic and diabetic syndromes

Protein kinase Cι: Human oncogene, prognostic marker and therapeutic target

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