PKC-delta mediates activation of ERK1/2 and induction of iNOS by IL-1beta in vascular smooth muscle cells.
Although the inflammatory cytokine interleukin-1beta (IL-beta) is an important regulator of gene expression in vascular smooth muscle (VSM), the signal transduction pathways leading to transcriptional activation upon IL-1beta stimulation are poorly understood. Recent studies have implicated IL-1beta-mediated ERK1/2 activation in the upregulation of type II nitric oxide synthase (iNOS) in VSM. We report that these events are mediated in a phospholipase C (PLC)- and protein kinase C (PKC)-delta-dependent manner utilizing a signaling mechanism independent of p21(ras) (Ras) and Raf1 activation. Stimulation of rat aortic VSM cells with IL-1beta activated PLC-gamma and pharmacological inhibition of PLC attenuated IL-1beta-induced ERK1/2 activation and subsequent iNOS expression. Stimulation with IL-1beta activated PKC-alpha and -delta, which was blocked using the PLC inhibitor U-73122. Pharmacological studies using isoform-specific PKC inhibitors and adenoviral overexpression of constitutively active PKC-delta indicated that ERK1/2 activation was PKC-alpha independent and PKC-delta dependent. Similarly, adenoviral overexpression of constitutively activated PKC-delta enhanced iNOS expression. IL-1beta stimulation did not induce either Ras or Raf1 activity. The absence of a functional role for Ras and Raf1 related to ERK1/2 activation and iNOS expression was further confirmed by adenoviral overexpression of dominant-negative Ras and treatment with the Raf1 inhibitor GW5074. Taken together, we have outlined a novel transduction pathway implicating PKC-delta as a critical component of the IL-1-dependent activation of ERK in VSM cells.
Ginnan
Roman
R
Center for Cardiovascular Sciences, MC-8, Albany Medical College, Albany, NY 12208, USA. ginnanr@mail.amc.edu
Guikema
Benjamin J
BJ
Singer
Harold A
HA
Jourd'heuil
David
D
D000818:Animals; D001011:Aorta / Q000378:metabolism; D015153:Blotting, Western; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000378:metabolism*; D007375:Interleukin-1 / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D051745:Protein Kinase C-delta / Q000187:drug effects / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014158:Transcription, Genetic; D020703:ras GTPase-Activating Proteins / Q000378:metabolism
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D007527:Isoenzymes; D020703:ras GTPase-Activating Proteins; D052247:Nitric Oxide Synthase Type II; D019908:Proto-Oncogene Proteins c-raf; D051745:Protein Kinase C-delta; D048049:Extracellular Signal-Regulated MAP Kinases