Xiushan Wu
Hunan Normal University, China
Title: Do the valve endocardial progenitors originate from a single zebrafish blastula HPRG1+ cell?
Biography
Biography: Xiushan Wu
Abstract
The arguments regarding the origin of the endocardial progenitors remain unresolved. Here, we have identified a gene, tentatively named HPRG1 (heart progenitor regulation gene 1), through a large-scale screen of Drosophila mutants. The gene is expressed in heart valves in zebrafish and its expression pattern is conserved in mice. Knockdown of the gene resulted in a valve defect, suggesting it is involved in endocardial valve development. It is known that Isl1 or GATA4 positive cells are capable of differentiating into two cell types, endocardial and cardial progenitors and NKx2.5 is the direct activator of endocardial master regulator Etv2. Our results indicated that HPRG1 is expressed in a novel type of mesodermal progenitor cells that are co-expressed with each master regulators and HPRG1 activates the expressions of GATA4 and NKx2.5 and inhibits the expression of Isl1. It is especially interesting that HPRG1 determines the fate of a single cell of the 128-cells at zebrafish blastula stage, suggesting that it is a fate-determining gene. Thus, the HPRG1 positive blastula cells provide an appropriate experimental system for exploring the specification mechanism of the endocardial progenitors. A mechanism for heart valve progenitor specification beginning with HPRG1 through GATA4, Isl1 and NKx2.5 is under investigation.