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HOP Signaling

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Cardiac myocyte proliferation and their differentiation early in development are dependent on the coordinate expression and action of SRF (Serum Response Factor), GATA4 (GATA Binding Protein-4) and the homeodomain factor NKX2.5 (NK2 Transcription Factor Related Locus-5). All three of these factors are expressed in developing cardiomyocytes and induce expression of cardiac genes. HOP (Homeodomain-Only Protein) physically interacts with SRF and inhibits activation of SRF-dependent transcription by inhibiting SRF binding to DNA. HOP gene encodes the smallest known homeodomain protein. HOP acts to modulate SRF-dependent transcription and cardiac-specific gene expression in the absence of intrinsic DNA binding capability (Ref.1). Although HOP is a homeodomain protein, it lacks a DNA-binding domain indicating that it does not regulate gene expression directly. SRF plays [...]


1.Hopping to the beat. Hop regulation of cardiac gene expression.
Kook H, Epstein JA.
Trends Cardiovasc. Med. 2003 Oct;13(7):261-4.
2.Hop is an unusual homeobox gene that modulates cardiac development.
Mullins MC, Epstein JA.
Cell. 2002 Sep 20;110(6):713-23.
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