In zebrafish, ventricular myosin heavy chain (vmhc) gene is initially expressed at the anterior lateral mesoderm and thereafter its expression is restricted to the cardiac ventricle. The transcriptional control mechanisms in regulating chamber-specific expression of myosin heavy chains are not well defined. We isolated and analyzed zebrafish vmhc upstream region to examine the spatial and temporal regulation of vmhc using transgenic and transient expression techniques. Promoter deletion analyses defined a basal promoter region sufficient to drive vmhc expression in the ventricle and an upstream fragment necessary for repressing ectopic vmhc expression in the atrium. The transcriptional mechanism that prevents vmhc expression in the atrium is mediated through Nkx2.5 binding elements (NKE). We have further discovered that paired-related homeobox transcriptional factor 2 (Prx2/S8)-like binding elements are required for promoting vmhc expression, and Prrx1b, a Prx-related homeobox protein, participates in the regulation of vmhc expression with other transcriptional factors. Developmental Dynamics 238:1760-1767, 2009. (C) 2009 Wiley-Liss, Inc.
[1]Fudan Univ, Key Lab Mol Med, Shanghai Med Sch, Shanghai 200433, Peoples R China.
[2]Vanderbilt Univ, Sch Med, Dept Med, Nashville, TN 37212 USA.
[3]Vanderbilt Univ, Sch Med, Dept Cell & Dev Biol, Nashville, TN 37212 USA.
[4]Fudan Univ, Childrens Hosp, Shanghai 200433, Peoples R China.
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