A bioinformatics approach to identifying fetal development genes

Gene regulation of fetal development is not well understood. In part, insulin and insulin-like growth factors (IGF) modulate placental steroid synthesis (PSS), which in turn modulates fetal growth. However, many of the genes that participate in this function remain to be identified. To find such genes, we examined the expression patterns of known IGF and placental steroid synthesis (IGF/PSS) genes in 1176 human cDNA libraries. We found a set of eight known IGF/PSS genes (PL-4, hCG, PAPP-A, EMBP, PLAP, P450 aromatase, P450scc, and 3-beta-HSD) that shared a highly similar expression profile across these libraries. We used these eight as bait in a search for other genes that showed very similar expression, and that might thus be related in function. We found ten genes closely co-expressed with the eight bait genes, but not previously reported as linked to IGF/PSS. Of these ten, six were previously reported as associated with cell growth in fetal and/or cancer tissues (malignant melanoma metastasis suppressor, PLAC-1, PSG10, PSG-beta1, serine palmitoyl transferase, and TONDU). Four are EST sequences, here named PLAC2, PLAC3, PLAC4, and PLAC5. Co-expression provides a method to identify which human genes are promising candidates for further experiments to determine their roles in fetal development.