The Transcription Factor Atonal homolog 8 Regulates Gata4 and Friend of Gata-2 during Vertebrate Development

David R Rawnsley,Jiping Xiao,John S Lee,Xi Liu,Patricia Mericko-Ishizuka,Vinayak Kumar,Jie He,Arindam Basu,Minmin Lu,Francis C Lynn,Michael Pack,Rosa Gasa,Mark L Kahn

doi:10.1074/jbc.m113.463083

Abstract

GATA and Friend of GATA (FOG) form a transcriptional complex that plays a key role in cardiovascular development in both fish and mammals. In the present study we demonstrate that the basic helix-loop-helix transcription factor Atonal homolog 8 (Atoh8) is required for development of the heart in fish but not in mice. Genetic studies reveal that Atoh8 interacts specifically with Gata4 and Fog1 during development of the heart and swim bladder in the fish. Biochemical studies reveal that ATOH8, GATA4, and FOG2 associate in a single complex in vitro. In contrast to fish, ATOH8-deficient mice exhibit normal cardiac development and loss of ATOH8 does not alter cardiac development in Gata4(+/-) mice. This species difference in the role of ATOH8 is explained in part by LacZ and GFP reporter alleles that reveal restriction of Atoh8 expression to atrial but not ventricular myocardium in the mouse. Our findings identify ATOH8 as a novel regulator of GATA-FOG function that is required for cardiac development in the fish but not the mouse. Whether ATOH8 modulates GATA-FOG function at other sites or in more subtle ways in mammals is not yet known.

Highlights

GATA and Friend of GATA (FOG) proteins are critical transcriptional regulators of multiple organ systems in vertebrate development
Our studies reveal essential roles for Atonal homolog 8 (Atoh8) in zebrafish cardiac and swim bladder development that are performed in concert with Gata and Fog transcription factors
Biochemical studies suggest that ATOH8-GATA-FOG interactions are conserved among the mouse proteins, but extensive genetic studies in the mouse fail to reveal an essential in vivo role for ATOH8, alone or with GATA4, in mice

Summary

Background

GATA and FOG proteins are critical transcriptional regulators of multiple organ systems in vertebrate development. Genetic studies reveal that Atoh interacts with Gata and Fog during development of the heart and swim bladder in the fish. ATOH8-deficient mice exhibit normal cardiac development and loss of ATOH8 does not alter cardiac development in Gata4؉/؊ mice This species difference in the role of ATOH8 is explained in part by LacZ and GFP reporter alleles that reveal restriction of Atoh expression to atrial but not ventricular myocardium in the mouse. We demonstrate that Atoh associates biochemically with Gata and Fog transcription factors and functions with these factors during cardiac and swim bladder development in the fish. Using morpholino knockdown of atoh, we identify a required role for atoh in the developing zebrafish heart and swim bladder, organs that require Gata factor function to develop. Expression analysis of Atoh using reporter alleles in the mouse suggests that the discrepancy between the mouse and fish loss of function phenotypes may be explained by restriction of Atoh expression to atrial myocardium in the mouse

EXPERIMENTAL PROCEDURES

RESULTS

Findings

DISCUSSION