EXPRESSION AND CDNA SEQUENCE OF HELIX DESTABILIZING PROTEIN (HDP) IN RAT LUNG

The current study was undertaken to investigate genes that show altera tion in expression during late fetal rat lung development. Using the d ifferential display (DD) method an initially unknown transcript was fo und to be abundant on day 18 compared to day 22 of gestation. This fin ding was confirmed by RNA blot analysis. Subsequent screening of a rat lung cDNA library with the unknown DD cDNA as a probe revealed a clon e that encodes helix destabilizing protein (HDP), similar to that repo rted in rat brain (J Biol Chem. 1986, 261:3536-3543. Although there we re several differences between lung and brain cDNAs at the 3' untransl ated region (UTR), the 5' end was well conserved. There was a gradual decrease in HDP mRNA content beyond day 18 of gestation, as lung matur ation increased. Similarly, a lower content of HDP mRNA was observed i n maternal heart and brain tissues than in fetal heart and brain tissu es from day 18 of gestation. Maternal dexamethasone treatment that pro motes lung maturation did not have an impact on HDP expression. Becaus e of the much higher abundance of HDP mRNA during fetal organ developm ent compared to adult tissues, we speculate that HDP plays an importan t role during lung development. A portion of this work was previously presented (FASEB J. 1996;10-A26).