Mutations in the ANKRD1 gene encoding CARP are responsible for human dilated cardiomyopathy.
ABSTRACT Dilated cardiomyopathy (DCM) is familial in approximately 30% of cases, and mutations have been identified in several genes. However, in a majority of familial cases, the responsible genes are still to be discovered. The ANKRD1 gene is over-expressed in heart failure in human and animal models. The encoded protein CARP interacts with partners such as myopalladin or titin, previously shown to be involved in DCM. We hypothesized that mutations in ANKRD1 could be responsible for DCM.
We sequenced the coding region of ANKRD1 from 231 independent DCM cases. We identified five missense mutations (three sporadic and two familial) absent from 400 controls and affecting highly conserved residues. Expression of the mutant CARP proteins after transfection in rat neonate cardiomyocytes indicated that most of them led to both significantly less repressor activity measured in a reporter gene assay and greater phenylephrin-induced hypertrophy, suggesting altered function of CARP mutant proteins.
On the basis of genetic and functional analysis of CARP mutations, we have identified ANKRD1 as a new gene associated with DCM, accounting for approximately 2% of cases.
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ABSTRACT: Muscle ankyrin-repeat proteins (MARPs) have been shown to serve diverse functions within cardiac and skeletal muscle cells. Apart from their interactions with sarcomeric proteins like titin or myopalladin that locate them along myofilaments, MARPs are able to shuttle to the nucleus where they act as modulators for a variety of transcription factors. The deregulation of MARPs in many cardiac and skeletal myopathies contributes to their use as biomarkers for these diseases. Many of their functions are attributed to their domain composition. MARPs consist of an N-terminal coiled-coil domain responsible for their dimerization. The C-terminus contains a series of ankyrin repeats, whose best-characterized function is to bind to the N2A region of the giant sarcomeric protein titin. Here we investigate the nature of their dimerization and their interaction with titin more closely. We demonstrate that the coiled-coil domain in all MARPs enables their homo- and hetero-dimerization in antiparallel fashion. Protein complementation experiments indicate further antiparallel binding of the ankyrin repeats to titin's N2A region. Binding of MARP to titin also affects its PKA mediated phosphorylation. We demonstrate further that MARPs themselves are phosphorylated by PKA and PKC, potentially altering their structure or function. These studies elucidate structural relationships within the stretch-responsive MARP/titin complex in cross-striated muscle cells, and may relate to disease relevant posttranslational modifications of MARPs and titin that alter muscle compliance. Anat Rec, 297:1615–1629, 2014. © 2014 Wiley Periodicals, Inc.The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 09/2014; 297(9). · 1.34 Impact Factor
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ABSTRACT: The gene ankyrin repeat domain 1 (Ankrd1) is an enigmatic gene and may exert pleiotropic function dependent on its expression level, subcellular localization and even types of pathological stress, but it remains unclear how these factors influence the fate of cardiomyocytes. Here we attempted to investigate the role of CARP on cardiomyocyte hypertrophy. In neonatal rat ventricular cardiomyocytes (NRVCs), angiotensin II (Ang II) increased the expression of both calpain 1 and CARP, and also induced cytosolic translocation of CARP, which was abrogated by a calpain inhibitor. In the presence of Ang-II in NRVCs, infection with a recombinant adenovirus containing rat Ankrd1 cDNA (Ad-Ankrd1) enhanced myocyte hypertrophy, the upregulation of atrial natriuretic peptide and β-myosin heavy chain genes and calcineurin proteins as well as nuclear translocation of nuclear factor of activated T cells. Cyclosporin A attenuated Ad-Ankrd1-enhanced cardiomyocyte hypertrophy. Intra-myocardial injection of Ad-Ankrd1 in mice with transverse aortic constriction (TAC) markedly increased the cytosolic CARP level, the heart weight/body weight ratio, while short hairpin RNA targeting Ankrd1 inhibited TAC-induced hypertrophy. The expression of calcineurin was also significantly increased in Ad-Ankrd1-infected TAC mice. Olmesartan (an Ang II receptor antagonist) prevented the upregulation of CARP in both Ang II-stimulated NRVCs and hearts with pressure overload. These findings indicate that overexpression of Ankrd1 exacerbates pathological cardiac remodeling through the enhancement of cytosolic translocation of CARP and upregulation of calcineurin.PLoS ONE 08/2014; 9(8):e104040. · 3.53 Impact Factor
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ABSTRACT: Background: We sought to characterize the landscape of structural variation associated with the subset of congenital cardiac defects characterized by left-sided obstruction. Methods: Cases with left-sided cardiac defects (LSCD) and pediatric controls were uniformly genotyped and assessed for copy number variant (CNV) calls. Significance testing was performed to ascertain differences in overall CNV incidence, and for CNV enrichment of specific genes and gene functions in LSCD cases relative to controls. Results: A total of 257 cases of European descent and 962 ethnically matched, disease-free pediatric controls were included. Although there was no difference in CNV rate between cases and controls, a significant enrichment in rare LSCD CNVs was detected overall (p = 7.30 × 10−3, case/control ratio = 1.26) and when restricted either to deletions (p = 7.58 × 10−3, case/control ratio = 1.20) or duplications (3.02 × 10−3, case/control ratio = 1.43). Neither gene-based, functional nor knowledge-based analyses identified genes, loci or pathways that were significantly enriched in cases as compared to controls when appropriate corrections for multiple tests were applied. However, several genes of interest were identified by virtue of their association with cardiac development, known human conditions, or reported disruption by CNVs in other patient cohorts. Conclusion: This study examines the largest cohort to date with LSCD for structural variation. These data suggest that CNVs play a role in disease risk and identify numerous genes disrupted by CNVs of potential disease relevance. These findings further highlight the genetic heterogeneity and complexity of these disorders. Birth Defects Research (Part A), 2014. © 2014 Wiley Periodicals, Inc.Birth Defects Research Part A Clinical and Molecular Teratology 07/2014; 100(12). · 2.27 Impact Factor