The transcription factor GATA 4 promotes myocardial regeneration in neonatal mice

Abstract

Heart failure is often the consequence of insufficient cardiac regeneration. Neonatal mice retain a certain capability of myocardial regeneration until postnatal day (P)7, although the underlying transcriptional mechanisms remain largely unknown. We demonstrate here that cardiac abundance of the transcription factor GATA4 was high at P1, but became strongly reduced at P7 in parallel with loss of regenerative capacity. Reconstitution of cardiac GATA4 levels by adenoviral gene transfer markedly improved cardiac regeneration after cryoinjury at P7. In contrast, the myocardial scar was larger in cardiomyocyte‐specific Gata4 knockout (CM‐G4‐KO) mice after cryoinjury at P0, indicative of impaired regeneration, which was accompanied by reduced cardiomyocyte proliferation and reduced myocardial angiogenesis in CM‐G4‐KO mice. Cardiomyocyte proliferation was also diminished in cardiac explants from CM‐G4‐KO mice and in isolated cardiomyocytes with reduced GATA4 expression. Mechanistically, decreased GATA4 levels caused the downregulation of several pro‐regenerative genes (among them interleukin‐13, Il13) in the myocardium. Interestingly, systemic administration of IL‐13 rescued defective heart regeneration in CM‐G4‐KO mice and could be evaluated as therapeutic strategy in the future.

Induction of cardiomyocyte proliferation and angiogenesis protects neonatal mice from pressure overload–associated maladaptation

“…In mice, cardiomyocyte GATA4 promotes intrauterine cardiac development, in part by driving cardiomyocyte proliferation; however, in the adult, GATA4 triggers cardiac hypertrophy, cell survival, and angiogenesis during pressure overload (17)(18)(19). As demonstrated by us and others, the high cardiac levels of GATA4 shortly after birth are necessary for neonatal mouse heart regeneration after myocardial injury at P1, as well as for zebrafish cardiac regeneration, because GATA4 promotes cardiomyocyte proliferation and capillary growth (15,20,21).…”

“…In order to be able to induce regeneration in patients suffering from pressure overload-induced cardiomyopathy in the future, one needs to identify crucial upstream regulators that promote this regenerative response. We have previously shown that GATA4 is highly abundant in the myocardium of 1-day-old mice and that it is essential for cardiac regeneration after myocardial infarction at this age, but its expression is dramatically reduced by P7 (15). Crossing our RNA-seq results from the current study with published myocardial GATA4 ChIP-seq data revealed that the majority (74%) of the upregulated genes in the regenerative compared with the nonregenerative phase after nTAC are bound by GATA4 in proximity to their TSS and are therefore likely direct targets of GATA4 (24).…”

“…Cell culture. Neonatal rat cardiomyocyte were isolated from 1-to 3-day-old neonatal rats, as previously described (15). The cells were treated with either 500 ng/ml rapamycin or solvent (0.2% sodium carboxymethyl cellulose and 0.25% polysorbate-80 in water; MilliporeSigma) or 500 ng/ml PTK or DMSO (NEB) for 24 hours in the presence of 15% FBS.…”

“…Echocardiography and Doppler flow velocity measurement. For echocardiography, mice were anesthetized with 0.5%-1.0% isoflurane and placed on a heating pad to maintain body temperature, as described (15). Noninvasive, echocardiographic parameters were measured with a linear 30-MHz transducer (Vevo 3100, Visualsonics).…”

“…Current research efforts aim to identify central regulators of neonatal heart regeneration that are differentially expressed after injury between P1 and P7, in order to design potentially novel therapeutic strategies for promoting cardiac restoration after myocardial infarction. Accordingly, we recently demonstrated a high myocardial expression of the transcription factor GATA4 shortly after birth at P1, which strongly diminishes until P7 (15). GATA4 belongs to the GATA family of transcription factors, which all share a conserved 2 zinc finger-containing DNA binding domain and bind to the DNA motif (A/T)GATA(A/G) (16).…”