Identification of Dep-1, a new gene regulated by the transcription factor Pax-3, as a marker for altered embryonic gene expression during diabetic pregnancy.

Abstract

The causes of diabetic embryopathy, in which congenital malformations arise in the early developing embryo of a pregnant mother with preexisting diabetes, are poorly understood. Previously, we reported that malformations may be caused by abnormal expression of important regulatory genes in the embryo (1). In particular, using a mouse model of diabetic embryopathy, a threefold increase in neural tube defects (NTDs) appears to result from reduced expression of Pax-3 (1). P a x - 3 e n c o d e s a transcription factor that is required for neural tube, neural crest, and somitic mesoderm development. Thus, altered expression of genes that are regulated as part of a Pax3‐dependent process may result from diabetic pregnancy, and altered expression of some of these genes may contribute to defective embryonic development. There are very few identified genes that are transcriptionally regulated as part of a Pax-3‐dependent process (2‐5), none of which, with the exception of the gene encoding N-CAM (6,7), which may be regulated posttranscriptionally by Pax-3, participate in neural tube development. To further characterize the molecular defects that occur as a consequence of altered expression of P a x - 3 during diabetic e m b r y o p a t h y, it is necessary to identify additional markers of Pax-3‐deficient transcriptional responses. Toward this end, we used differential polymerase chain reaction (PCR) display (8), using RNA obtained from day-9.5 embryos of diabetic and nondiabetic mice and from embryos derived from the S p l o t c h strain of mice, which carry loss of function P a x 3 alleles. A 237‐base pair (bp) cDNA that corresponds to a transcript that is reduced in embryos of diabetic mice and in homozygous S p l o t c h embryos was identified by this method. Sequence analysis of this cDNA suggested that it had not previously been identified. Because we identified this gene from embryos of diabetic mice that are prone to embryopat h y, we named it D e p - 1 (Diabetic Embryopathy-1).