High impact information on pitx2a

• Asymmetric isoform expression occurs in non-overlapping domains, with pitx2c in left dorsal diencephalon and developing gut and pitx2a in left heart primordium [1].
• Ectopic expression of pitx2 isoforms results in distinct morphological and molecular phenotypes, indicating that pitx2a and pitx2c have divergent regulatory functions [1].
• The pitx2 homeobox protein is required early for endoderm formation and nodal signaling. [2].
• Inhibition of pitx2 function using a chimeric EnR-pitx2 blocked specification of the mesoderm and endoderm and caused severe embryonic defects resembling those seen when Nodal signaling is inhibited [2].
• Our results provide direct evidence that pitx2 function is required for normal specification of the endodermal and mesodermal germ layers [2].

Anatomical context of pitx2a

• Following inhibition of pitx2 function, the fate of ventral vegetal blastomeres was shifted from an endodermal to a more mesodermal fate, an effect that was reversed by wild-type pitx2 [2].
• We found that pitx2 is expressed very early during Xenopus and zebrafish development and in many regions where Nodal signaling is required, including the presumptive mesoderm and endoderm at the blastula and gastrula stages and the prechordal mesoderm at later stages [2].

Other interactions of pitx2a

• The normally left-sided Nodal signal spaw as well as its inhibitor lefty are expressed bilaterally, while pitx2 may appear random or bilateral [3].

References