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XB-ART-36523
Dev Biol November 15, 2007; 311 (2): 297-310.

The amphibian second heart field: Xenopus islet-1 is required for cardiovascular development.

Brade T , Gessert S , Kühl M , Pandur P .


Abstract
Islet-1 is a LIM-homeodomain transcription factor that has been defined to label cardiac progenitor cells of the second heart field. Here we provide the first analysis of the expression pattern of Xenopus islet-1 (Xisl-1) in the context of cardiovascular development. During early stages of heart development Xisl-1 is co-expressed with Nkx2.5 in the cardiac crescent in Xenopus supporting the notion of an initially single heart field. At subsequent stages of cardiogenesis the expression domains of Xisl-1 and Nkx2.5 become more distinct with Xisl-1 being detected more anterior to Nkx2.5, however both factors continue to be co-expressed in the dorsal mesocardium and pericardial roof of the linear heart tube. The presence of a cardiac Xisl-1 progenitor pool in an amphibian whose heart lacks an anatomically separated right ventricle is intriguing. Functional analyses show that Xisl-1 is required for normal heart development. Inhibition of Xisl-1 results in defects in heart morphogenesis and in the downregulation of early cardiac markers implicating a role for Xisl-1 in cardiac specification. Additionally, Xisl-1 loss-of-function affects the expression of several vascular markers demonstrating the involvement of Xisl-1 in vasculogenesis.

PubMed ID: 17900553
Article link: Dev Biol

Genes referenced: actc1 actl6a frzb2 isl1 nkx2-5 tbx20 tnni3
Morpholinos: isl1 MO1


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