Developmental expression of D7, a novel gene identified in the embryonic mouse heart

Little is currently known regarding the molecular regulation of heart development. D7 is a novel gene isolated from the embryonic mouse heart. The purpose of this current study is to determine the normal spatial and temporal expression patterns of D7 transcripts during mouse development. cDNA probes were generated from both the 5' and 3' regions of a 2.6 kb D7 clone by RT-PCR. Nucleotide sequences of the cloned cDNA fragments were confirmed prior to use in Northern blot analyses and in situ hybridization studies. Northern blot analysis of whole mouse embryo RNA (E7-E17) using a ³²P-labeled probe from the 5' region of D7 detects 3 distinct mRNA transcripts (1.35, 3.5, and 4 kb) in all stages examined. The 1.35 kb transcript is more abundant than the larger transcripts at each of the developmental stages. Preliminary in situ hybridization studies in E12.5-13 mouse embryos with antisense probes from the 5' region of D7 demonstrate a ubiquitous expression pattern while antisense probe from the 3' region of the D7 gene demonstrate a more restricted expression pattern within the developing heart endothelium, the limb buds and the somite regions. These results indicate that D7 has multiple mRNA transcripts expressed during development. The restricted expression pattern of the larger D7 transcripts suggest a possible role in endothelial-mediated remodeling events during organogenesis. Additional studies are being conducted to more fully characterize the complete spatial and temporal expression of D7 mRNA transcripts during mouse development.