title: EPAC expression and function in cardiac fibroblasts and myofibroblasts.
abstract: In the heart, cardiac fibroblasts (CF) and cardiac myofibroblasts (CMF) are the main cells responsible for wound healing after cardiac insult. Exchange protein activated by cAMP (EPAC) is a downstream effector of cAMP, and it has been not completely studied on CF. Moreover, in CMF, which are the main cells responsible for cardiac healing, EPAC expression and function are unknown. We evaluated in both CF and CMF the effect of transforming growth factor β1 (TGF-β1) on EPAC-1 expression. We also studied the EPAC involvement on collagen synthesis, adhesion, migration and collagen gel contraction.
  
  
  METHODS
  Rat neonatal CF and CMF were treated with TGF-β1 at different times and concentrations. EPAC-1 protein levels and Rap1 activation were measured by western blot and pull down assay respectively. EPAC cellular functions were determined by adhesion, migration and collagen gel contraction assay; and collagen expression was determined by western blot.
  
  
  RESULTS
  TGF-β1 through Smad and JNK significantly reduced EPAC-1 expression in CF, while in CMF this cytokine increased EPAC-1 expression through ERK1/2, JNK, p38, AKT and Smad3. EPAC activation was able to induce higher Rap1-GTP levels in CMF than in CF. EPAC and PKA, both cAMP effectors, promoted CF and CMF adhesion on fibronectin, as well as CF migration; however, this effect was not observed in CMF. EPAC but not PKA activation mediated collagen gel contraction in CF, while in CMF both PKA and EPAC mediated collagen gel contraction. Finally, the EPAC and PKA activation reduced collagen synthesis in CF and CMF.
  
  
  CONCLUSIONS
  TGF-β1 differentially regulates the expression of EPAC in CF and CMF; and EPAC regulates differentially CF and CMF functions associated with cardiac remodeling.
authors.affiliation: Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Chile.
authors.forename: Ivonne
authors.initials: I
authors.lastname: Olmedo
authors.forename: Claudia
authors.initials: C
authors.lastname: Muñoz
authors.forename: Nancy
authors.initials: N
authors.lastname: Guzmán
authors.forename: Mabel
authors.initials: M
authors.lastname: Catalán
authors.forename: Raúl
authors.initials: R
authors.lastname: Vivar
authors.forename: Pedro
authors.initials: P
authors.lastname: Ayala
authors.forename: Claudio
authors.initials: C
authors.lastname: Humeres
authors.forename: Pablo
authors.initials: P
authors.lastname: Aránguiz
authors.forename: Lorena
authors.initials: L
authors.lastname: García
authors.forename: Victoria
authors.initials: V
authors.lastname: Velarde
authors.forename: Guillermo
authors.initials: G
authors.lastname: Díaz-Araya
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000096:biosynthesis* / Q000502:physiology*; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D058628:Myofibroblasts / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D020257:Ventricular Remodeling / Q000502:physiology
chemical_list: D020662:Guanine Nucleotide Exchange Factors; C526973:Rapgef3 protein, rat; D053773:Transforming Growth Factor beta1; D003094:Collagen
keywords: Adhesion; Cardiac fibroblast and myofibroblast; Collagen; EPAC-1; Migration; TGF-beta1