Effects of antisense misexpression of CFC on downstream flectin protein expression during heart looping.

Dextral looping of the heart is regulated on multiple levels. In humans, mutations of the genes CFC and Pitx2/RIEG result in laterality-associated cardiac anomalies. In animal models, a common read-out after the misexpression of laterality genes is heart looping direction.

Directionality of heart looping: effects of Pitx2c misexpression on flectin asymmetry and midline structures.

A critical regulatory laterality gene expressed in the left side of the straight heart tube during development is Pitx2, which when mutated in humans underlies Rieger's Syndrome. Previously reported results have indicated that, when using gain-of-function and loss-of function approaches of the chick cPitx2c isoform, this results in randomization of heart looping. To determine whether Pitx2c misexpression affects downstream morphogenesis by altering the expression of specific proteins in the myocardium during looping, after experimental manipulations, we analyzed immunohistochemically for the extracellular matrix molecule flectin that normally is expressed predominantly in the left lateral plate mesoderm (LPM) and left side of the straight chick heart tube before and during looping.