Document Detail


Correction of metabolic abnormalities in a rodent model of obesity, metabolic syndrome, and type 2 diabetes mellitus by inhibitors of hepatic protein kinase C-ι
MedLine Citation:
PMID:  22225955     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Excessive activity of hepatic atypical protein kinase (aPKC) is proposed to play a critical role in mediating lipid and carbohydrate abnormalities in obesity, the metabolic syndrome, and type 2 diabetes mellitus. In previous studies of rodent models of obesity and type 2 diabetes mellitus, adenoviral-mediated expression of kinase-inactive aPKC rapidly reversed or markedly improved most if not all metabolic abnormalities. Here, we examined effects of 2 newly developed small-molecule PKC-ι/λ inhibitors. We used the mouse model of heterozygous muscle-specific knockout of PKC-λ, in which partial deficiency of muscle PKC-λ impairs glucose transport in muscle and thereby causes glucose intolerance and hyperinsulinemia, which, via hepatic aPKC activation, leads to abdominal obesity, hepatosteatosis, hypertriglyceridemia, and hypercholesterolemia. One inhibitor, 1H-imidazole-4-carboxamide, 5-amino-1-[2,3-dihydroxy-4-[(phosphonooxy)methyl]cyclopentyl-[1R-(1a,2b,3b,4a)], binds to the substrate-binding site of PKC-λ/ι, but not other PKCs. The other inhibitor, aurothiomalate, binds to cysteine residues in the PB1-binding domains of aPKC-λ/ι/ζ and inhibits scaffolding. Treatment with either inhibitor for 7 days inhibited aPKC, but not Akt, in liver and concomitantly improved insulin signaling to Akt and aPKC in muscle and adipocytes. Moreover, both inhibitors diminished excessive expression of hepatic, aPKC-dependent lipogenic, proinflammatory, and gluconeogenic factors; and this was accompanied by reversal or marked improvements in hyperglycemia, hyperinsulinemia, abdominal obesity, hepatosteatosis, hypertriglyceridemia, and hypercholesterolemia. Our findings highlight the pathogenetic importance of insulin signaling to hepatic PKC-ι in obesity, the metabolic syndrome, and type 2 diabetes mellitus and suggest that 1H-imidazole-4-carboxamide, 5-amino-1-[2,3-dihydroxy-4-[(phosphonooxy)methyl]cyclopentyl-[1R-(1a,2b,3b,4a)] and aurothiomalate or similar agents that selectively inhibit hepatic aPKC may be useful treatments.
Authors:
Mini P Sajan; Sonali Nimal; Stephen Mastorides; Mildred Acevedo-Duncan; C Ronald Kahn; Alan P Fields; Ursula Braun; Michael Leitges; Robert V Farese
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-5
Journal Detail:
Title:  Metabolism: clinical and experimental     Volume:  -     ISSN:  1532-8600     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375267     Medline TA:  Metabolism     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Published by Elsevier Inc.
Affiliation:
Medical and Research Services, James A. Haley Veterans Medical Center, Tampa, FL 33612, USA.
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