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Proc Natl Acad Sci U S A. 2011 Aug 16;108(33):13576-81. doi: 10.1073/pnas.1106911108. Epub 2011 Aug 8.

Iroquois homeobox gene 3 establishes fast conduction in the cardiac His-Purkinje network.

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  • 1Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA.

Abstract

Rapid electrical conduction in the His-Purkinje system tightly controls spatiotemporal activation of the ventricles. Although recent work has shed much light on the regulation of early specification and morphogenesis of the His-Purkinje system, less is known about how transcriptional regulation establishes impulse conduction properties of the constituent cells. Here we show that Iroquois homeobox gene 3 (Irx3) is critical for efficient conduction in this specialized tissue by antithetically regulating two gap junction-forming connexins (Cxs). Loss of Irx3 resulted in disruption of the rapid coordinated spread of ventricular excitation, reduced levels of Cx40, and ectopic Cx43 expression in the proximal bundle branches. Irx3 directly represses Cx43 transcription and indirectly activates Cx40 transcription. Our results reveal a critical role for Irx3 in the precise regulation of intercellular gap junction coupling and impulse propagation in the heart.

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PMID:
21825130
[PubMed - indexed for MEDLINE]
PMCID:
PMC3158173
Free PMC Article

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