We previously established that increased hyaluronan synthesis in ductus arteriosus (DA) compared with aorta (Ao) endothelial cells (EC) from early gestation fetal lambs (100-d, term = 145 d) is transforming growth factor-β (TGF-β)-dependent. We now address whether this is associated with tissue- specific and developmentally up-regulated expression of TGF-β1 in the 100- d DA EC. Immunoprecipitation revealed TGF-β synthesis doubled in DA versus Ao EC from 100-d gestation lambs (p < 0.05). In 138-d DA EC, TGF-β protein levels were reduced (p < 0.05) and comparable to those in Ao cells. Western immunoblotting with a β1 isoform-specific antibody confirmed these differences as being related to TGF-β1. Northern blot analysis demonstrated that TGF-β1 mRNA levels were slightly but not significantly increased in 100-d DA compared with Ao EC, despite its short half-life in DA (9.5 h) versus Ao EC (20 h). TGF-β1 mRNA levels were reduced in 138-d DA and Ao EC (p < 0.05), and the mRNA half-life was comparable in DA (9 h) versus Ao (13 h). Nuclear run-on analysis confirmed increased TGF-β1 mRNA transcription in 100-d DA versus Ao and 138-d DA EC. Thus, up-regulated TGF-β1 expression in 100-d DA compared with Ao cells is due to increased transcription and translation of a relatively unstable mRNA, and its down-regulation in 138-d DA and Ao EC is related to reduced mRNA transcription and stability, respectively.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health