title: Distinct effects of voltage- and store-dependent calcium influx on stretch-induced differentiation and growth in vascular smooth muscle.
abstract: Stretch of the vascular wall stimulates smooth muscle hypertrophy by activating the MAPK and Rho/Rho kinase (ROK) pathways. We investigated the role of calcium in this response. Stretch-stimulated expression of contractile and cytoskeletal proteins in mouse portal vein was inhibited at mRNA and protein levels by blockade of voltage-dependent Ca(2+) entry (VDCE). In contrast, blockade of store-operated Ca(2+) entry (SOCE) did not affect smooth muscle marker expression but decreased global protein synthesis. Activation of VDCE caused membrane translocation of RhoA followed by phosphorylation of its downstream effectors LIMK-2 and cofilin-2. Stretch-activated cofilin-2 phosphorylation depended on VDCE but not on SOCE. VDCE was associated with increased mRNA expression of myocardin, myocyte enhancer factor (MEF) -2A and -2D, and smooth muscle marker genes, all of which depended on ROK activity. SOCE increased ERK1/2 phosphorylation and c-Fos expression but had no effect on phosphorylation of LIMK-2 and cofilin-2 or on myocardin and MEF2 expression. Knockdown of MEF2A or -2D eliminated the VDCE-induced activation of myocardin expression and increased basal c-Jun and c-Fos mRNA levels. These results indicate that MEF2 mediates VDCE-dependent stimulation of myocardin expression via the Rho/ROK pathway. In addition, SOCE activates the expression of immediate-early genes, known to be regulated by MEF2 via Ca(2+)-dependent phosphorylation of histone deacetylases, but this mode of Ca(2+) entry does not affect the Rho/ROK pathway. Compartmentation of Ca(2+) entry pathways appears as one mechanism whereby extracellular and membrane signals influence smooth muscle phenotype regulation, with MEF2 as a focal point.
authors.affiliation: Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden.
authors.forename: Jingli
authors.initials: J
authors.lastname: Ren
authors.forename: Sebastian
authors.initials: S
authors.lastname: Albinsson
authors.forename: Per
authors.initials: P
authors.lastname: Hellstrand
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D051340:Cofilin 2 / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D055785:Gene Knockdown Techniques; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D054461:Lim Kinases / Q000235:genetics / Q000378:metabolism; D064326:MEF2 Transcription Factors; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D010766:Phosphorylation / Q000502:physiology; D011169:Portal Vein / Q000166:cytology / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein; D000099251:Myocardin
chemical_list: D002118:Calcium; D051340:Cofilin 2; D006655:Histone Deacetylases; D054461:Lim Kinases; D064326:MEF2 Transcription Factors; D048052:Mitogen-Activated Protein Kinase 3; D018006:Myogenic Regulatory Factors; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D015534:Trans-Activators; D020741:rho GTP-Binding Proteins; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D000099251:Myocardin; C495816:Cfl2 protein, mouse; C578036:Mef2a protein, mouse; C578044:Mef2d protein, mouse; C095325:Limk2 protein, mouse; C526380:RhoA protein, mouse