Angiotensin AT(1) receptor stimulates heat shock protein 27 phosphorylation in vitro and in vivo.
The angiotensin type 1 receptor (AT(1)) exerts a variety of its signaling and cellular actions through its effects on protein phosphorylation. Phosphoproteomic analysis of angiotensin (Ang) II-stimulated aortic smooth muscle cells revealed that heat shock protein 27 (HSP27) represents a major protein phosphorylation target of the AT(1) signaling pathway. Stimulation of cells with Ang II resulted in 1.7-fold (P<0.05) and 5.5-fold (P<0.001) increases in HSP27 phosphoisoforms at pI 5.7 and pI 5.4, respectively. This was accompanied by a 54% (P<0.01) decrease in the nonphosphorylated HSP27 isoform, located at pI 6.4. Treatment of samples with alkaline phosphatase reversed this redistribution of HSP27 phosphoisoforms. Ang II-stimulated HSP27 phosphorylation was completely blocked by pretreatment of cells with the AT(1) antagonist CV11974. Phosphoamino acid analysis demonstrated that Ang II-induced phosphorylation of both HSP27 phosphoisoforms occurred exclusively on serine. Protein kinase C inhibition completely blocked phorbol ester-induced HSP27 phosphorylation but did not impair Ang II-stimulated phosphorylation of HSP27, suggesting that AT(1) increased HSP27 phosphorylation by a protein kinase C-independent pathway. Intrajugular infusion of Ang II in rats increased HSP27 in aorta by 1.7-fold (P<0.02), and this response was inhibited by CV11974. These results suggest that Ang II-induced HSP27 phosphorylation is a physiologically relevant AT(1) signaling event. Because serine phosphorylation of HSP27 blocks its ability to cap F-actin, Ang II/AT(1)-induced HSP27 phosphorylation may play a key role in actin filament remodeling required for smooth muscle cell migration and contraction.
Meier
M
M
Vascular Cell Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA.
King
G L
GL
Clermont
A
A
Perez
A
A
Hayashi
M
M
Feener
E P
EP
D000809:Angiotensins / Q000008:administration & dosage; D000818:Animals; D002478:Cells, Cultured; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008297:Male; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000378:metabolism*
D000809:Angiotensins; D006360:Heat-Shock Proteins; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D011493:Protein Kinase C