Microarray analysis of retinoid-dependent gene activity during rat embryogenesis: Increased collagen fibril production in a model of retinoid insufficiency

Retinoic acid (RA) is an essential mediator of embryogenesis. Some, but not all, of its targets have been identified. We previously developed a rat model of gestational retinoid deficiency (RAD; Power et al. [1999],Dev. Dyn. 216:469-480) and generated embryos with developmental impairments that closely resemble genetic and dietary models of retinoid insufficiency. Here, we used microarray analysis and expression profiling to identify 88 transcripts whose abundance was altered under conditions of retinoid insufficiency, as compared with normal embryos. Among these, the induction by R AD of genes involved in collagen I synthesis (COLA1, IA2 and VA2, prolyl-4-hydroxylase-alpha1) and protein galactosylation (galactokinase, ABO galactosyltransferase,. UDP-galactose transporter-related protein) was especially noteworthy because extracellular matrix regulates many developmental I events. We, also identified several genes involved With stress, responses (cathepsin H, UBC2E, IGFBP3, smoothelin). Real-time, polymerase chain reaction. analysis of selected candidates revealed excellent agreement with the, array findings. Further validation came from the demonstration that these. genies were similarly dysregulated in two genetic, models of retinoid insufficiency, the retinol binding protein null-mutant embryo and the RaIdh2 null-mutant embryo. In situ hybridization of RAID embryos. found increased. collagen IA1 and IGFBP3 mRNA within the connective mesenchyme and vasculature respectively, and a failure to repress the growth factor midkine within the RAD neural tube. Many of the. identified genes were not known previously to respond to retinoid status and will provide new insights to retinoid roles and, to the. consequences of retinoid insufficiency. Developmental Dynamics 229:886-898, 2004. (C) 2004 Wiley-Liss, Inc.