GATA4 and the Two Sides of Gene Expression Reprogramming

Abstract

See related article, pages 837–845 During embryonic development as well as in postnatal life, cardiac cells are continuously exposed to a host of extracellular signals to which they adapt and respond by activating intracellular signaling pathways and modulating the expression of nuclear genes. In the adult heart, the most common and easily recognized response to stressful stimuli is hypertrophy of cardiomyocytes and remodeling of the entire organ.1 This reactive growth response requires de novo synthesis of contractile and structural proteins, obtained through a complex series of events culminating in gene expression reprogramming.2 GATA4 is a zinc-finger transcription factor highly expressed in cardiomyocytes at different developmental stages where it regulates the transcription of several structural and regulatory genes, including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), α- and β-myosin heavy chain (MHC).3 In human hearts, GATA4 has also been demonstrated to be a critical regulator of cardiac development, as shown by the association between GATA4 mutations and the presence of congenital cardiac malformations.4 The specific effects of GATA4 deletion during embryonic age have been extensively investigated in genetically modified mouse models.5–7 Mice homozygous for a GATA4 null allele6 or homozygous GATA4-deficient mice (GATA4−/−)5 die early in development because of abnormal …