Smyd1 Orchestrates Early Heart Development Through Positive and Negative Gene Regulation.

Zhen Wang,Jing Liu,Robert J Schwartz,Yanlin Ma,Fei Sun,Qi Li

doi:10.3389/fcell.2021.654682

Abstract

SET and MYND domain-containing protein 1 (Smyd1) is a striated muscle-specific histone methyltransferase. Our previous work demonstrated that deletion of Smyd1 in either cardiomyocytes or the outflow tract (OFT) resulted in embryonic lethality at E9.5, with cardiac structural defects such as truncation of the OFT and right ventricle and impaired expansion and proliferation of the second heart field (SHF). The cardiac phenotype was accompanied by the downregulation of ISL LIM Homeobox 1 (Isl1) and upregulation of atrial natriuretic factor (ANF). However, the mechanisms of Smyd1 regulating Isl1 and ANF during embryonic heart development remain to be elucidated. Here, we employed various biochemical and molecular biological approaches including chromatin immunoprecipitation polymerase chain reaction (ChIP-PCR), pGL3 fluorescence reporter system, and co-immunoprecipitation (CoIP) and found that Smyd1 interacted with absent small homeotic-2-like protein (ASH2L) and activated the promoter of Isl1 by trimethylating H3K4. We also found that Smyd1 associated with HDAC to repress ANF expression using trichostatin A (TSA), a deacetylase inhibitor. In conclusion, Smyd1 participates in early heart development by upregulating the expression of Isl1 and downregulating the expression of ANF.

Highlights

Congenital heart disease affects 0.8–1 child per 100 live births and is responsible for the majority of prenatal deaths (Bonnet, 2017)
The mutation that disrupted SET and MYND domain-containing protein 1 (Smyd1) binding to SB4 reduced the activation of the ISL LIM Homeobox 1 (Isl1)-WT reporter by Smyd1, while the mutation on the SB3 site did not affect the activation of pLG3-Isl1 by Smyd1 (Figure 2E). These findings suggest that SB4 but not SB3 is important for Smyd1-dependent transcriptional activity of the Isl1 gene, which was consistent with the findings obtained from ChIPqPCR and Electrophoretic Mobility Shift Assays (EMSAs)
Recent study showed that Isl1 can produce notable therapeutic effects in the infarcted heart (Li et al, 2017) and that Isl1-cardiovascular progenitor cells repaired after myocardial infarction (Bartulos et al, 2016)

Summary

Introduction

Congenital heart disease affects 0.8–1 child per 100 live births and is responsible for the majority of prenatal deaths (Bonnet, 2017). Previous studies have shown that serum response factor (SRF), NK2 homeobox 5 (Nkx2.5), GATA binding protein 4 (GATA4), and Tbox transcription factor 20 (Tbx20) are important for both first and second heart fields, while Hand, Isl, Myocyte Enhancer Factor 2C (Mef2c), and fibroblast growth factor 10 (Fgf10) are important for the formation of the second heart field (Rochais et al, 2014; Quaranta et al, 2018; Chen et al, 2019; Han et al, 2019). Smyd Orchestrates Early Heart Development (Cai et al, 2003; Kattman et al, 2006; Moretti et al, 2006). Those findings suggest that Isl is critical for cardiac progenitor commitment and early heart development

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