Small interfering RNA knocks down heat shock factor-1 (HSF-1) and exacerbates pro-inflammatory activation of NF-kappaB and AP-1 in vascular smooth muscle cells.
OBJECTIVE
Heat shock and elevated expression of heat shock proteins suppress activation of the pro-inflammatory transcription factor NF-kappaB. We hypothesized that knocking down the expression of heat shock factor-1 (HSF-1) with RNAi technology would exacerbate angiotensin (Ang) II-induced inflammatory injury in vascular smooth muscle cells (VSMC).


METHODS
Rat aorta A10 cells and human intestinal smooth muscle cells were grown without transfection or with transfection with HSF-1 small interfering RNA (siRNA), or negative control siRNA. Cells were stimulated with Ang II (100 nM) to activate the NF-kappaB signaling pathway.


RESULTS
HSF-1 siRNA significantly knocked down HSF-1 expression, and one of the downstream heat shock proteins (Hsp), Hsp27, in both cells lines. HSF-1 siRNA also affected cells stressed with heat shock or Ang II treatment. Ang II induced activation of NF-kappaB and AP-1 in untransfected VSMCs, however, Ang II induced significantly higher activities of these pro-inflammatory transcription factors in HSF-1 siRNA transfected cells. Control siRNA had no apparent effect on HSF-1 and Hsp27 expression and Ang II-induced NF-kappaB and AP-1 activation.


CONCLUSIONS
These data indicate that the knock down of HSF-1 exacerbates Ang II-induced inflammation in VSMCs, and suggests that heat shock proteins protect against inflammatory injury by suppression of pro-inflammatory transcription factors such as NF-kappaB and AP-1.
Chen
Yu
Y
Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5.
Currie
R William
RW
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D055551:HSP27 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007422:Intestines; D009131:Muscle, Smooth, Vascular / Q000276:immunology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000276:immunology* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D013268:Stimulation, Chemical; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014162:Transfection / Q000379:methods
D004268:DNA-Binding Proteins; D055551:HSP27 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D016328:NF-kappa B; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D000804:Angiotensin II