Transient and transgenic analysis of the zebrafish ventricular myosin heavy chain (vmhc) promoter: An inhibitory mechanism of ventricle-specific gene expression

Authors

  • Ruilin Zhang,

    1. Department of Biochemistry and Molecular Biology/Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota
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  • Xiaolei Xu

    Corresponding author
    1. Department of Biochemistry and Molecular Biology/Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota
    • Department of Biochemistry and Molecular Biology/Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Stabile 4-10, 200 1st Street SW, Rochester, MN 55905
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Abstract

The zebrafish ventricular myosin heavy chain (vmhc) gene exhibits restricted expression in the ventricle. However, the molecular mechanism underlying this chamber-specific expression is unclear. Here, we exploited both transient and transgenic technologies to dissect the zebrafish vmhc promoter. We demonstrated that a combination of two transient assays in this animal model quickly identified chamber-specific cis-elements, isolating a 2.2 kb fragment upstream from the vmhc gene that can drive ventricle-specific expression. Furthermore, deletion analysis identified multiple cis-elements that exhibited cardiac-specific expression. To achieve chamber specificity, a distal element was required to coordinate with and suppress a proximal enhancer element. Finally, we discovered that Nkx2.5-binding sites (NKE) were essential for this repressive function. In summary, our study of the zebrafish vmhc promoter suggests that ventricle-specific expression is achieved through an inhibitory mechanism that suppresses expression in the atrium. Developmental Dynamics 238:1564–1573, 2009. © 2009 Wiley-Liss, Inc.

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