GATA4 suppresses satellite cell differentiation

Tomohide Takaya, Atsushi Asakura.

Stem Cell institute, Paul & Sheila Wellstone Muscular Dystrophy Center, Department of Neurology, University of Minnesota Medical School, Minneapolis, MN, USA.

The Greg Marzolf Jr Symposium 2013 (Minneapolis, USA), 2013/10/30 (Poster).

Abstract

GATA transcription factors are involved in various cell processes including cell proliferation and differentiation. Functions of GATA1, GATA2, and GATA3 in hematopoietic stem cells and those of GATA4, GATA5, and GATA6 in cardiovascular cells have been well studied. However, the roles of GATA factors in skeletal muscle development are still unclear. In this study, we investigated whether GATA factors regulate skeletal muscle satellite cell functions. qPCR and immunostaining indicated that GATA2, GATA3, GATA4, and GATA6 were expressed in growing myoblasts, while disappeared in differentiating myotubes. Overexpression experiments demonstrate that GATA4 and GATA6 but not GATA2 or GATA3 repressed myogenic differentiation judged by the number of myosin heavy chain-positive cells and cell fusion index. Recent work demonstrates that DNA-binding and transcriptional activity of GATA4 are regulated by post-translational acetylation. We utilized non-acetylated GATA4-K^mut which loses DNA-binding activity for the further GATA4 functional analysis. In contrast to intact GATA4, GATA4-K^mut overexpression showed no suppression of myogenic differentiation. These results demonstrate that DNA-binding activity is required for GATA4 to suppress myogenic differentiation. To explore downstream genes regulated by GATA4, we compared gene expressions between control and GATA4-overexpressing myoblasts. Overexpression of GATA4 dramatically reduced mRNAs of myogenic transcription factors (MyoD, myogenin), muscle structural proteins (skeletal α-actin, myosin light and heavy chains), and cyclin-dependent kinase inhibitors (p21, p27, p57). Interestingly, a negative bHLH transcription factor Mash4 was upregulated by GATA4. We recently identified that Mash4 is expressed in satellite cells and suppresses myogenic differentiation to promote satellite cell self-renewal. Therefore, these data suggest that GATA4 functions as a suppressor of myogenic differentiation mediated through Mash4 induction.