title: Targeted inhibition of ANKRD1 disrupts sarcomeric ERK-GATA4 signal transduction and abrogates phenylephrine-induced cardiomyocyte hypertrophy.
abstract: OBJECTIVE
  Accumulating evidence suggest that sarcomere signalling complexes play a pivotal role in cardiomyocyte hypertrophy by communicating stress signals to the nucleus to induce gene expression. Ankyrin repeat domain 1 (ANKRD1) is a transcriptional regulatory protein that also associates with sarcomeric titin; however, the exact role of ANKRD1 in the heart remains to be elucidated. We therefore aimed to examine the role of ANKRD1 in cardiomyocyte hypertrophic signalling.
  
  
  RESULTS
  In neonatal rat ventricular myocytes, we found that ANKRD1 is part of a sarcomeric signalling complex that includes ERK1/2 and cardiac transcription factor GATA4. Treatment with hypertrophic agonist phenylephrine (PE) resulted in phosphorylation of ERK1/2 and GATA4 followed by nuclear translocation of the ANKRD1/ERK/GATA4 complex. Knockdown of Ankrd1 attenuated PE-induced phosphorylation of ERK1/2 and GATA4, inhibited nuclear translocation of the ANKRD1 complex, and prevented cardiomyocyte growth. Mice lacking Ankrd1 are viable with normal cardiac function. Chronic PE infusion in wild-type mice induced significant cardiac hypertrophy with reactivation of the cardiac fetal gene program which was completely abrogated in Ankrd1 null mice. In contrast, ANKRD1 does not play a role in haemodynamic overload as Ankrd1 null mice subjected to transverse aortic constriction developed cardiac hypertrophy comparable to wild-type mice.
  
  
  CONCLUSIONS
  Our study reveals a novel role for ANKRD1 as a selective regulator of PE-induced signalling whereby ANKRD1 recruits and localizes GATA4 and ERK1/2 in a sarcomeric macro-molecular complex to enhance GATA4 phosphorylation with subsequent nuclear translocation of the ANKRD1 complex to induce hypertrophic gene expression.
authors.affiliation: Department of Medicine, Cardiovascular Division, Vanderbilt University School of Medicine, 2220 Pierce Ave, Preston Research Building, Rm 332, Nashville, TN 37232, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhong
authors.affiliation: Department of Medicine, Cardiovascular Division, Vanderbilt University School of Medicine, 2220 Pierce Ave, Preston Research Building, Rm 332, Nashville, TN 37232, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Chiusa
authors.affiliation: Department of Medicine, Cardiovascular Division, Vanderbilt University School of Medicine, 2220 Pierce Ave, Preston Research Building, Rm 332, Nashville, TN 37232, USA Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Cadar
authors.affiliation: Department of Medicine, Cardiovascular Division, Vanderbilt University School of Medicine, 2220 Pierce Ave, Preston Research Building, Rm 332, Nashville, TN 37232, USA.
authors.forename: Angel
authors.initials: A
authors.lastname: Lin
authors.affiliation: Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Samaras
authors.affiliation: Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA Research Service, Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37232, USA.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Davidson
authors.affiliation: Department of Medicine, Cardiovascular Division, Vanderbilt University School of Medicine, 2220 Pierce Ave, Preston Research Building, Rm 332, Nashville, TN 37232, USA Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA chee.lim@vanderbilt.edu.
authors.forename: Chee C
authors.initials: CC
authors.lastname: Lim
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000139:chemically induced / Q000378:metabolism*; D002478:Cells, Cultured; D050991:GATA4 Transcription Factor / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010656:Phenylephrine / Q000633:toxicity*; D010766:Phosphorylation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C104844:Ankrd1 protein, mouse; D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D009124:Muscle Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D010656:Phenylephrine
keywords: CARP; GATA4; Hypertrophy; Sarcomere; Titin