Cited by 60Metabolism, Diabetes, and CancerAdipokines, Inflammation, and Metabolic DiseasesProtein Kinase Regulation and GTPase Signaling

Role of atypical protein kinase C in activation of sterol regulatory element binding protein-1c and nuclear factor kappa B (NFκB) in liver of rodents used as a model of diabetes, and relationships to hyperlipidaemia and insulin resistance

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Sajan, M. P., Standaert, M. L., Rivas, J., Miura, A., Kanoh, Y., Soto, J., Taniguchi, C. M., Kahn, C. R. +1 more·2009·Diabetologia

Abstract

Aims/hypothesis Previous findings in rodents used as a model of diabetes suggest that insulin activation of atypical protein kinase C (aPKC) is impaired in muscle, but, unexpectedly, conserved in liver, despite impaired hepatic protein kinase B (PKB/Akt) activation. Moreover, aPKC at least partly regulates two major transactivators: (1) hepatic sterol receptor binding protein-1c (SREBP-1c), which controls lipid synthesis; and (2) nuclear factor kappa B (NFkappaB), which promotes inflammation and systemic insulin resistance.Methods In Goto-Kakizaki rats used as a model of type 2 diabetes, we examined: (1) whether differences in hepatic aPKC and PKB activation reflect differences in activation of IRS-1- and IRS-2-dependent phosphatidylinositol 3-kinase (PI3K); (2) whether hepatic SREBP-1c and NFkappaB are excessively activated by aPKC; and (3) metabolic consequences of excessive activation of hepatic aPKC, SREBP-1c and NFkappaB.Results In liver, as well as in muscle, IRS-2/PI3K activation by insulin was intact, whereas IRS-1/PI3K activation by insulin was impaired. Moreover, hepatic IRS-2 is known to control hepatic aPKC during insulin activation. Against this background, selective inhibition of hepatic aPKC by adenoviral-mediated expression of mRNA encoding kinase-inactive aPKC or short hairpin RNA targeting Irs2 mRNA and partially depleting hepatic IRS-2 diminished hepatic SREBP-1c production and NFkappaB activities, concomitantly improving serum lipids and insulin signalling in muscle and liver. Similar improvements in SREBP-1c, NFkappaB and insulin signalling were seen in ob/ob mice following inhibition of hepatic aPKC.Conclusions/interpretation In diabetic rodent liver, diminished PKB activation may largely reflect impaired IRS-1/PI3K activation, while conserved aPKC activation reflects retained IRS-2/PI3K activity. Hepatic aPKC may also contribute importantly to excessive SREPB-1c and NFkappaB activities. Excessive hepatic aPKC-dependent activation of SREBP-1c and NFkappaB may contribute importantly to hyperlipidaemia and systemic insulin resistance.

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Authors
Sajan, M. P., Standaert, M. L., Rivas, J., Miura, A., Kanoh, Y., Soto, J., Taniguchi, C. M., Kahn, C. R., & Farese, R. V.
Affiliations
  • James A. Haley Veterans' Hospital (US)
  • Harvard University (US)
Corresponding author
Farese, R. V.
Venue
Diabetologia
Published
2009-04-09
Volume
52
Issue
6
Pages
1197-1207
ISSN
  • 0012-186X (ISSN-L)
  • 1432-0428
OpenAlex
W2147359359
Cited by
60
References
24
Citations by year
2026: 3 · 2025: 1 · 2023: 3 · 2022: 1 · 2021: 2 · 2020: 4 · 2017: 1 · 2016: 1 · 2015: 9 · 2014: 8 · 2013: 5 · 2012: 5
FWCI
2.95
Type
journal article
Language
en
Open access
Locations
  • Diabetologia (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • U.S. Department of Veterans Affairs
  • National Institutes of Health (38079)
  • National Institute of Diabetes and Digestive and Kidney Diseases (DK 30136, R01DK038079, R01DK031036, DK 38079, R01DK065969)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Metabolism, Diabetes, and Cancer
  • Health Sciences › Medicine › Epidemiology › Adipokines, Inflammation, and Metabolic Diseases
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Kinase Regulation and GTPase Signaling
Keywords
SREBP-1c, NF-κB, insulin resistance, hyperlipidemia, type 2 diabetes, IRS-1, insulin receptor substrate 2, phosphatidylinositol 3-kinase, Akt, hepatic lipid synthesis, liver inflammation, Goto-Kakizaki rats, ob/ob mice
MeSH terms
Analysis of Variance, Animals, Blood Glucose, Cholesterol, Diabetes Mellitus, Disease Models, Animal, Hyperlipidemias, Insulin Resistance, Liver, Male, Muscles, Protein Kinase C, Triglycerides, Blotting, Western, NF-kappa B, Rats, Wistar, Phosphatidylinositol 3-Kinases, Electrophoretic Mobility Shift Assay, Rats, Sterol Regulatory Element Binding Protein 1, Insulin Receptor Substrate Proteins

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