Charron F, Paradis P, Bronchain O, Nemer G, Nemer M
Laboratoire de Développement et Différenciation Cardiaques, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada.
Mol Cell Biol. 1999 Jun;19(6):4355-65. doi: 10.1128/MCB.19.6.4355.
Two members of the GATA family of transcription factors, GATA-4 and GATA-6, are expressed in the developing and postnatal myocardium and are equally potent transactivators of several cardiac promoters. However, several in vitro and in vivo lines of evidence suggest distinct roles for the two factors in the heart. Since identification of the endogenous downstream targets of GATA factors would greatly help to elucidate their exact functions, we have developed an adenovirus-mediated antisense strategy to specifically inhibit GATA-4 and GATA-6 protein production in postnatal cardiomyocytes. Expression of several endogenous cardiac genes was significantly down-regulated in cells lacking GATA-4 or GATA-6, indicating that these factors are required for the maintenance of the cardiac genetic program. Interestingly, transcription of some genes like the alpha- and beta-myosin heavy-chain (alpha- and beta-MHC) genes was preferentially regulated by GATA-4 due, in part, to higher affinity of GATA-4 for their promoter GATA element. However, transcription of several other genes, including the atrial natriuretic factor and B-type natriuretic peptide (ANF and BNP) genes, was similarly down-regulated in cardiomyocytes lacking one or both GATA factors, suggesting that GATA-4 and GATA-6 could act through the same transcriptional pathway. Consistent with this, GATA-4 and GATA-6 were found to colocalize in postnatal cardiomyocytes and to interact functionally and physically to provide cooperative activation of the ANF and BNP promoters. The results identify for the first time bona fide in vivo targets for GATA-4 and GATA-6 in the myocardium. The data also show that GATA factors act in concert to regulate distinct subsets of genes, suggesting that combinatorial interactions among GATA factors may differentially control various cellular processes.
转录因子GATA家族的两个成员GATA-4和GATA-6在发育中和出生后的心肌中表达，并且是几种心脏启动子的同等有效的反式激活因子。然而，多条体外和体内证据表明这两种因子在心脏中具有不同的作用。由于鉴定GATA因子的内源性下游靶标将极大地有助于阐明它们的确切功能，我们开发了一种腺病毒介导的反义策略，以特异性抑制出生后心肌细胞中GATA-4和GATA-6蛋白的产生。在缺乏GATA-4或GATA-6的细胞中，几种内源性心脏基因的表达显著下调，表明这些因子是维持心脏遗传程序所必需的。有趣的是，某些基因如α和β肌球蛋白重链（α-MHC和β-MHC）基因的转录优先受GATA-4调控，部分原因是GATA-4对其启动子GATA元件具有更高的亲和力。然而，包括心房利钠因子和B型利钠肽（ANF和BNP）基因在内的其他几个基因的转录在缺乏一种或两种GATA因子的心肌细胞中同样下调，这表明GATA-4和GATA-6可能通过相同的转录途径起作用。与此一致的是，发现GATA-4和GATA-6在出生后心肌细胞中共定位，并在功能和物理上相互作用，以协同激活ANF和BNP启动子。这些结果首次确定了心肌中GATA-4和GATA-6真正的体内靶标。数据还表明，GATA因子协同作用以调节不同的基因子集，这表明GATA因子之间的组合相互作用可能以不同方式控制各种细胞过程。
