OBJECTIVE: Our goal was to test whether formin homology protein 1 (FHOD1) plays a significant role in the regulation of smooth muscle cell (SMC) differentiation and, if so, whether Rho kinase (ROCK)-dependent phosphorylation in the diaphanous autoinhibitory domain is an important signaling mechanism that controls FHOD1 activity in SMC. METHODS AND RESULTS: FHOD1 is highly expressed in aortic SMCs and in tissues with a significant SMC component. Exogenous expression of constitutively active FHOD1, but not wild-type, strongly activated SMC-specific gene expression in 10T1/2 cells. Treatment of SMC with the RhoA activator sphingosine-1-phosphate increased FHOD1 phosphorylation at Thr1141, and this effect was completely prevented by inhibition of ROCK with Y-27632. Phosphomimetic mutations to ROCK target residues enhanced FHOD1 activity, suggesting that phosphorylation interferes with FHOD1 autoinhibition. Importantly, knockdown of FHOD1 in SMC strongly inhibited sphingosine-1-phosphate-dependent increases in SMC differentiation marker gene expression and actin polymerization, suggesting that FHOD1 plays a major role in RhoA-dependent signaling in SMC. CONCLUSIONS: Our results indicate that FHOD1 is a critical regulator of SMC phenotype and is regulated by ROCK-dependent phosphorylation. Thus, additional studies on the role of FHOD1 during development and the progression of cardiovascular disease will be important.
OBJECTIVE: Our goal was to test whether formin homology protein 1 (FHOD1) plays a significant role in the regulation of smooth muscle cell (SMC) differentiation and, if so, whether Rho kinase (ROCK)-dependent phosphorylation in the diaphanous autoinhibitory domain is an important signaling mechanism that controls FHOD1 activity in SMC. METHODS AND RESULTS:FHOD1 is highly expressed in aortic SMCs and in tissues with a significant SMC component. Exogenous expression of constitutively active FHOD1, but not wild-type, strongly activated SMC-specific gene expression in 10T1/2 cells. Treatment of SMC with the RhoA activator sphingosine-1-phosphate increased FHOD1 phosphorylation at Thr1141, and this effect was completely prevented by inhibition of ROCK with Y-27632. Phosphomimetic mutations to ROCK target residues enhanced FHOD1 activity, suggesting that phosphorylation interferes with FHOD1 autoinhibition. Importantly, knockdown of FHOD1 in SMC strongly inhibited sphingosine-1-phosphate-dependent increases in SMC differentiation marker gene expression and actin polymerization, suggesting that FHOD1 plays a major role in RhoA-dependent signaling in SMC. CONCLUSIONS: Our results indicate that FHOD1 is a critical regulator of SMC phenotype and is regulated by ROCK-dependent phosphorylation. Thus, additional studies on the role of FHOD1 during development and the progression of cardiovascular disease will be important.
Authors: A Jahraus; M Egeberg; B Hinner; A Habermann; E Sackman; A Pralle; H Faulstich; V Rybin; H Defacque; G Griffiths Journal: Mol Biol Cell Date: 2001-01 Impact factor: 4.138
Authors: P G Anderson; N J Boerth; M Liu; D B McNamara; T L Cornwell; T M Lincoln Journal: Arterioscler Thromb Vasc Biol Date: 2000-10 Impact factor: 8.311
Authors: Bo Cen; Ahalya Selvaraj; Rebecca C Burgess; Johann K Hitzler; Zhigui Ma; Stephan W Morris; Ron Prywes Journal: Mol Cell Biol Date: 2003-09 Impact factor: 4.272
Authors: Sankar Maiti; Alphee Michelot; Christopher Gould; Laurent Blanchoin; Olga Sokolova; Bruce L Goode Journal: Cytoskeleton (Hoboken) Date: 2012-06
Authors: Javier Gordon Ogembo; Danny A Milner; Keith G Mansfield; Scott J Rodig; George F Murphy; Jeffery L Kutok; Geraldine S Pinkus; Joyce D Fingeroth Journal: J Immunol Date: 2012-04-04 Impact factor: 5.422
Authors: Lindsey E Malloy; Kuo-Kuang Wen; Alyson R Pierick; Elesa W Wedemeyer; Sarah E Bergeron; Nicole D Vanderpool; Melissa McKane; Peter A Rubenstein; Heather L Bartlett Journal: J Biol Chem Date: 2012-06-29 Impact factor: 5.157