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Mechanism of anthracycline-mediated down-regulation of GATA4 in the heart.

ABSTRACT: Anthracyclines such as daunorubicin (DNR) and doxorubicin are effective cancer chemotherapeutic agents, but can induce cardiotoxicity. GATA4 has been shown to serve as a survival factor of cardiac muscle cells, and anthracyclines promote apoptosis in part by down-regulating GATA4. The present study investigated the mechanism of anthracycline action to down-regulate GATA4.DNR inhibited the transcriptional activity exhibited by the 250 bp conserved region immediately upstream from the transcriptional start site of the Gata4 gene. Mapping this region identified that the CCAAT-binding factor/nuclear factor-Y (CBF/NF-Y) binding to the CCAAT box was inhibited by DNR in HL-1 cardiac muscle cells and in perfused isolated mouse hearts. The DNR action on the Gata4 promoter was found to be dependent on p53, since DNR promoted nuclear binding of p53 to CBF/NF-Y and pifithrin-? (a p53 inhibitor) attenuated DNR down-regulation of GATA4.Anthracycline down-regulation of GATA4 is mediated by the inhibition of Gata4 gene transcription via a novel mechanism that involves the p53-dependent inhibition of CBF/NF-Y binding to the CCAAT box within the Gata4 promoter.

SUBMITTER: Park AM

PROVIDER: S-EPMC3058732 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Mechanism of anthracycline-mediated down-regulation of GATA4 in the heart.

Park Ah-Mee AM Nagase Hiroko H Liu Lingling L Vinod Kumar Shilpashree S Szwergold Nava N Wong Chi-Ming CM Suzuki Yuichiro J YJ

Cardiovascular research 20101116 1

<h4>Aims</h4>Anthracyclines such as daunorubicin (DNR) and doxorubicin are effective cancer chemotherapeutic agents, but can induce cardiotoxicity. GATA4 has been shown to serve as a survival factor of cardiac muscle cells, and anthracyclines promote apoptosis in part by down-regulating GATA4. The present study investigated the mechanism of anthracycline action to down-regulate GATA4.<h4>Methods and results</h4>DNR inhibited the transcriptional activity exhibited by the 250 bp conserved region i ...[more]

PMID: 21084315

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Project description:Doxorubicin (Adriamycin) is an effective anti-cancer drug, but its clinical usage is limited by a dose-dependent cardiotoxicity characterized by widespread sarcomere disarray and loss of myofilaments. Cardiac ankyrin repeat protein (CARP, ANKRD1) is a transcriptional regulatory protein that is extremely susceptible to doxorubicin; however, the mechanism(s) of doxorubicin-induced CARP depletion and its specific role in cardiomyocytes have not been completely defined. We report that doxorubicin treatment in cardiomyocytes resulted in inhibition of CARP transcription, depletion of CARP protein levels, inhibition of myofilament gene transcription, and marked sarcomere disarray. Knockdown of CARP with small interfering RNA (siRNA) similarly inhibited myofilament gene transcription and disrupted cardiomyocyte sarcomere structure. Adenoviral overexpression of CARP, however, was unable to rescue the doxorubicin-induced sarcomere disarray phenotype. Doxorubicin also induced depletion of the cardiac transcription factor GATA4 in cardiomyocytes. CARP expression is regulated in part by GATA4, prompting us to examine the relationship between GATA4 and CARP in cardiomyocytes. We show in co-transfection experiments that GATA4 operates upstream of CARP by activating the proximal CARP promoter. GATA4-siRNA knockdown in cardiomyocytes inhibited CARP expression and myofilament gene transcription, and induced extensive sarcomere disarray. Adenoviral overexpression of GATA4 (AdV-GATA4) in cardiomyocytes prior to doxorubicin exposure maintained GATA4 levels, modestly restored CARP levels, and attenuated sarcomere disarray. Interestingly, siRNA-mediated depletion of CARP completely abolished the Adv-GATA4 rescue of the doxorubicin-induced sarcomere phenotype. These data demonstrate co-dependent roles for GATA4 and CARP in regulating sarcomere gene expression and maintaining sarcomeric organization in cardiomyocytes in culture. The data further suggests that concurrent depletion of GATA4 and CARP in cardiomyocytes by doxorubicin contributes in large part to myofibrillar disarray and the overall pathophysiology of anthracycline cardiomyopathy.

Project description:Recent studies indicate that mammals, including humans, maintain some capacity to renew cardiomyocytes throughout postnatal life. Yet, there is little or no significant cardiac muscle regeneration after an injury such as acute myocardial infarction. By contrast, zebrafish efficiently regenerate lost cardiac muscle, providing a model for understanding how natural heart regeneration may be blocked or enhanced. In the absence of lineage-tracing technology applicable to adult zebrafish, the cellular origins of newly regenerated cardiac muscle have remained unclear. Using new genetic fate-mapping approaches, here we identify a population of cardiomyocytes that become activated after resection of the ventricular apex and contribute prominently to cardiac muscle regeneration. Through the use of a transgenic reporter strain, we found that cardiomyocytes throughout the subepicardial ventricular layer trigger expression of the embryonic cardiogenesis gene gata4 within a week of trauma, before expression localizes to proliferating cardiomyocytes surrounding and within the injury site. Cre-recombinase-based lineage-tracing of cells expressing gata4 before evident regeneration, or of cells expressing the contractile gene cmlc2 before injury, each labelled most cardiac muscle in the ensuing regenerate. By optical voltage mapping of surface myocardium in whole ventricles, we found that electrical conduction is re-established between existing and regenerated cardiomyocytes between 2 and 4 weeks post-injury. After injury and prolonged fibroblast growth factor receptor inhibition to arrest cardiac regeneration and enable scar formation, experimental release of the signalling block led to gata4 expression and morphological improvement of the injured ventricular wall without loss of scar tissue. Our results indicate that electrically coupled cardiac muscle regenerates after resection injury, primarily through activation and expansion of cardiomyocyte populations. These findings have implications for promoting regeneration of the injured human heart.

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Mechanism of anthracycline-mediated down-regulation of GATA4 in the heart.

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Mechanism of anthracycline-mediated down-regulation of GATA4 in the heart.

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