Fatty acids modulate protein kinase C activation in porcine vascular smooth muscle cells independently of their effect on de novo diacylglycerol synthesis

X. Lu, X. Y. Yang, R. L. Howard, J. P. Walsh

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Aims/hypothesis. Diabetes-induced activation of protein kinase C has been associated with the development of vascular complications. Elevated de novo diacylglycerol synthesis has been postulated to underlie this protein kinase C activation. Diabetes also increases the circulating concentrations of non-esterified fatty acids, which are immediate precursors of diacylglycerol through the de novo pathway. We hypothesized that increased fatty acids contribute to de novo diacylglycerol synthesis and activation of protein kinase C in vascular cells. Methods. Primary cultures of porcine carotid smooth muscle cells were exposed to fatty acids, bound to albumin in physiologic ratios. Diacylglycerol and triacylglycerol were measured in extracts of these cells. Protein kinase C activation was measured as membrane translocation with isoform-specific antibodies. Results. Saturated fatty acids caused considerable accumulation of diacylglycerol through de novo synthesis. Unsaturated fatty acids increased triacylglycerol, but not diacylglycerol. Platelet-derived growth factor activated the α, ε and ζ protein kinase C isoforms. Activation of the α and ζ isoforms was amplified by oleate pretreatment but inhibited by palmitate. In the absence of growth factor stimulation, neither palmitate nor oleate had any effect on the membrane/cytosol distribution of any protein kinase C isoform. Conclusion/interpretation. Saturated fatty acids elicited de novo diacylglycerol synthesis in vascular smooth muscle cells without activating protein kinase C. Effects of fatty acids on protein kinase C activation by platelet-derived growth factor did not correlate with the effects on de novo diacylglycerol synthesis. These results indicate that de novo diacylglycerol synthesis is, by itself, insufficient to activate protein kinase C.

Original languageEnglish (US)
Pages (from-to)1136-1144
Number of pages9
JournalDiabetologia
Volume43
Issue number9
DOIs
StatePublished - 2000

Keywords

  • Cultured cells
  • Diabetes mellitus
  • Diacylglycerol
  • Non-esterified fatty acids
  • Platelet-derived growth factor
  • Protein kinase C
  • Vascular smooth muscle

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

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