Microarray analysis of homocysteine‐responsive genes in cardiac neural crest cells in vitro

Abstract

The amino acid homocysteine increases in the serum when there is insufficient folic acid or vitamin B 12 , or with certain mutations in enzymes important in methionine metabolism. Elevated homocysteine is related to increased risk for cardiovascular and other diseases in adults and elevated maternal homocysteine increases the risk for certain congenital defects, especially those that result from abnormal development of the neural crest and neural tube. Experiments with the avian embryo model have shown that elevated homocysteine perturbs neural crest/neural tube migration in vitro and in vivo. Whereas there have been numerous studies of homocysteine-induced changes in gene expression in adult cells, there is no previous report of a homocysteine-responsive transcriptome in the embryonic neural crest. We treated neural crest cells in vitro with exogenous homocysteine in a protocol that induces significant changes in neural crest cell migration. We used microarray analysis and expression profiling to identify 65 transcripts of genes of known function that were altered by homocysteine. The largest set of effected genes (19) included those with a role in cell migration and adhesion. Other major groups were genes involved in metabolism (13); DNA/RNA interaction (11); cell proliferation/apoptosis (10); and transporter/receptor (6). Although the genes identified in this experiment were consistent with prior observations of the effect of homocysteine upon neural crest cell function, none had been identified previously as response to homocysteine in adult cells.

Maternal intake of fat, riboflavin and nicotinamide and the risk of having offspring with congenital heart defects

“…Nevertheless, our findings are in line with the associations demonstrated between maternal dietary intake of nicotinamide and riboflavin and the risk of a child with an orofacial cleft or spina bifida [11,19]. CHDs share similarities in the pathogenesis of spina bifida and orofacial clefts, because of the involvement of neural crest cells which are very sensitive to exposures of folate and homocysteine [1,4,28]. Riboflavin and Cut off values were based on the lowest quartile of intake of the control mothers.…”

“…Furthermore, low dietary intakes of riboflavin and nicotinamide have been associated with an increased risk of orofacial clefts [29] and spina bifida [11], respectively. Neural tube defects and orofacial clefts share many similarities in the pathogenesis of CHDs as these birth defects originate from disturbances in neural crest cell behaviour by for example hyperhomocysteinemia and low folate [1,4,28]. Therefore, it is conceivable that nutritional factors implicated in the pathogenesis of neural tube defects and orofacial clefts also apply to CHDs.…”

Methionine synthase reductase deficiency results in adverse reproductive outcomes and congenital heart defects in mice

“…Clinical studies suggest that maternal hyperhomocysteinemia and hypomethioninemia are significant risk factors for CHD in offspring [14,20,32]. In chickens, homocysteine has been reported to induce CHD [33] and microarray analysis of cardiac neural crest cells showed differential expression of a large number of genes involved in cell migration and adhesion in response to homocysteine [34].…”

Homocysteine enhances cardiac neural crest cell attachment in vitro by increasing intracellular calcium levels

“…A recent microarray analysis of cardiac NC cells treated with Hcys in vitro found a down-regulation of expression of the gene encoding the potential-store-activated Ca 2ϩ channel, TRPC7 (transient receptor potential channel canonical C-member 7; Rosenquist et al, 2007). Therefore, many of the effects of elevated Hcys on NC morphogenesis in avian embryos could be due to altered Ca 2ϩ signaling.…”