Regulation of elastin synthesis in developing sheep nuchal ligament by elastin mRNA levels
Levels of elastin production in explant culture of fetal sheep nuchal ligament and corresponding levels of translatable elastin mRNA were determined in parallel studies during a period of rapid growth of the embryo. The identity of the explant culture and cell-free products was confirmed by peptide mapping, immunoprecipitation, and the characteristic lack of histidine and methionine. Elastin production was quantitated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and radioimmune precipitation. The translation products could be labeled with methionine only when NH2-terminally donated as f-Met-tRNAfMet. Explant cultures showed a large rise in elastin production from 70 days after conception to 150 days after conception. Cell-free translation of RNA demonstrated a parallel in elastin mRNA levels and in elastin mRNA per cell. It appears, therefore, that the marked emphasis the differentiating nuchal ligament places on elastin production is modulated, at least in part, by the quantities of available elastin mRNA.