siRNA knocks down Hsp27 and increases angiotensin II-Induced phosphorylated NF-κB p65 levels in aortic smooth muscle cells

Abstract.

Objective and design:

Angiotensin II (Ang II) induces the proinflammatory nuclear factor κB (NF-κB) in the vasculature. Heat shock and elevated levels of heat shock proteins (Hsps) decrease Ang II-induced NF-κB transcriptional activity and inflammation, but little is known about the role of specific Hsps. Here we used small interfering RNA (siRNA) technology to examine the role of Hsp27 in the Ang II-induced NF-κB signaling pathway.

Methods:

Hsp27 siRNA was transfected into rat aortic vascular smooth muscle (A10) and 48 hrs later, the cells were stressed with 100 nM of Ang II for up to 24 hrs. Hsp27 levels were determined by immunofluorescence microscopy and Western analysis and inhibitor κB-α (IκB-α), the p65 subunit of NF-κB, and IκB kinase (IKK) levels were determined by Western analysis.

Results:

When Hsp27 was specifically knocked down with Hsp27 siRNA in A10 cells there was a trend toward an increase in Ang II-induced phosphorylated p65. IκB-α and IKK-β levels were not changed by the knockdown of Hsp27.

Conclusion:

Hsp27 may regulate the phosphorylation of the p65 subunit of NF-κB in the Ang II-induced signaling pathway of NF-κB in A10 cells. The proinflammatory effects of Ang II on NF-κB in vascular smooth muscle cells may be through a non-canonical pathway and be dependent on p65 phosphorylation.