Protein kinase C epsilon mediates angiotensin II-induced activation of beta1-integrins in cardiac fibroblasts

Philipp Stawowy, Christian Margeta, Florian Blaschke, Carsten Lindschau, Chantel Spencer-Hänsch, Michael Leitges, Giuseppe Biagini, Eckart Fleck, Kristof Graf
Cardiovascular Research 2005 July 1, 67 (1): 50-9

OBJECTIVE: Angiotensin II (AII) promotes cardiac fibrosis by increased extracellular matrix production and enhanced interaction of matrix proteins with their cellular receptors, including integrins. AII and other growth factors augment beta(1)-integrin-dependent adhesion and spreading by "inside-out signaling" without affecting the total number of integrin receptors. "Inside-out signaling" involves specific signaling pathways, including protein kinase C (PKC), leading to activation of beta1-integrins. In the present study we investigated the mechanisms involved in AII-increased adhesion of adult rat cardiac fibroblasts (CFBs), obtained from Sprague-Dawley rats, to collagen I mediated by beta1-integrin.

METHODS AND RESULTS: Treatment of CFBs with AII induced a concentration-dependent increase in adhesion to collagen I (2.2-fold, p<0.01) within 3-6 h of treatment. This effect was mediated by beta1-integrin via the angiotensin AT1 receptor and was significantly reduced by protein kinase C inhibition. AII significantly induced phosphorylation of PKC epsilon (PKCepsilon), which is involved in beta1-integrin-dependent adhesion and motility, and phosphorylation of the cytoplasmatic tail of beta1-integrin at threonine 788/789, required for adhesion. Phosphorylation of beta1-integrin and an increase in adhesion was also induced by l-alpha-phosphatidylinositol-3,4,5-triphosphate (l-alpha-PIP3), an activator of endogenous PKCepsilon. AII failed to increase adhesion in myofibroblasts obtained from PKCepsilon (-/-) mice, but not in cells obtained from control mice. Co-immunoprecipitation and double immunofluorescence demonstrated that AII induced a close association of PKCepsilon with beta1-integrin in CFBs.

CONCLUSION: The present study demonstrates that AII increased beta1-integrin-dependent adhesion to collagen I in cardiac fibroblasts by inside-out signaling via PKCepsilon and phosphorylation of the cytoplasmatic tail of the beta1-integrin.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"