Meeting Abstract

P1.3  Jan. 4  The Effect of Homocysteine on Neural Crest Cell Migration and Expression of N-Cadherin and Associated Proteins CALLAWAY, KR*; WIENS, DJ; Univ. of Northern Iowa, Cedar Falls; Univ. of Northern Iowa, Cedar Falls kaciejo@uni.edu

At elevated levels the amino acid homocysteine has been linked to defects such as spina bifida and improper septation of the outflow tract of the heart. Neural crest cells (NCCs) originate from the neural tube, disassociate from their neighbors, and migrate throughout the body to form many essential structures. N-cadherin, a cell adhesion protein, plays a major role in cell shape change, long-range migration, and communication. RhoB, a Ras GTPase, is expressed as NCCs migrate and may play a role in their delamination. α-catenin is a member of the cadherin adhesion complex and can bind actin to modulate the cytoskeleton. Since homocysteine increases cell migration it is possible that it alters the expression and function of N-cadherin, rhoB, and/or α-catenin. To test this hypothesis the cardiac neural tube region was excised from stage 10-13 chick embryos and cultured for 24 hours. One group of explants was exposed to 100 mM D,L-homocysteine thiolactone while the other was left untreated (control). Explants were then fixed, immunostained with antibodies to N-cadherin, rhoB, or α-catenin and were subjected to color thresholding image analysis. N-cadherin expression was significantly reduced by homocysteine compared to controls, whereas rhoB expression was significantly increased. Preliminary results for α-catenin expression suggest it is not significantly altered. A 13.4% increase was observed in cell migration distance compared to controls. In vitro therefore, elevated homocysteine can be linked to an increase in cell migration distance, which can be explained in part by a significant reduction in the expression of the cell adhesion protein N-cadherin in combination with a significant increase in delamination inducing rhoB.