title: Mitogen-activated protein kinases and mitogen-activated protein kinase phosphatases mediate the inhibitory effects of all-trans retinoic acid on the hypertrophic growth of cardiomyocytes.
abstract: All-trans retinoic acid (RA) has been implicated in mediation of cardiac growth inhibition in neonatal cardiomyocytes. However, the associated signaling mechanisms remain unclear. Utilizing neonatal cardiomyocytes, we demonstrated that RA suppressed the hypertrophic features induced by cyclic stretch or angiotensin II (Ang II). Cyclic stretch- or Ang II-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAP kinase) was dose- and time-dependently inhibited by RA. Significant inhibition was observed by 5 microm RA, from 8 to 24 h of pretreatment. This inhibitory effect was not mediated at the level of mitogen-activated protein kinase kinases (MKKs), because RA had no effect on stretch- or Ang II-induced phosphorylation of MEK1/2, MKK4, and MKK3/6. However, the phosphatase inhibitor vanadate reversed the inhibitory effect of RA on MAP kinases and protein synthesis. RA up-regulated the expression level of MAP kinase phosphatase-1 (MKP-1) and MKP-2, and the time course was correlated with the inhibitory effect of RA on activation of MAP kinases. Overexpression of wild-type MKP-1 inhibited the phosphorylation of JNK and p38 in cardiomyocytes. These data indicated that MKPs were involved in the inhibitory effect of RA on MAP kinases. Using specific RAR and RXR antagonists, we demonstrated that both RARs and RXRs were involved in regulating stretch- or Ang II-induced activation of MAP kinases. Our findings provide the first evidence that the anti-hypertrophic effect of RA is mediated by up-regulation of MKPs and inhibition of MAP kinase signaling pathways.
authors.affiliation: Division of Molecular Cardiology, Department of Internal Medicine, Scott and White and The Texas A&M University System Health Science Center, College of Medicine, Temple, Texas 76504, USA.
authors.forename: Ants
authors.initials: A
authors.lastname: Palm-Leis
authors.forename: Ugra S
authors.initials: US
authors.lastname: Singh
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Herbelin
authors.forename: Greg D
authors.initials: GD
authors.lastname: Olsovsky
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Baker
authors.forename: Jing
authors.initials: J
authors.lastname: Pan
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology; D002455:Cell Division; D002478:Cells, Cultured; D054638:Dual Specificity Phosphatase 1; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D015870:Gene Expression; D017874:Immediate-Early Proteins / Q000235:genetics / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000166:cytology*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000187:drug effects; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018168:Receptors, Retinoic Acid / Q000032:analysis / Q000187:drug effects / Q000502:physiology; D047488:Retinoid X Receptors / Q000032:analysis / Q000187:drug effects / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D000804:Angiotensin II; D014212:Tretinoin; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D017027:Protein Tyrosine Phosphatases