Hypoxia upregulates the synthesis of TGF-beta 1 by human dermal fibroblasts.
In this report, we have investigated the secretion and synthesis of transforming growth factor-beta 1 (TGF-beta 1) by human dermal fibroblast cultures in response to hypoxia (2% oxygen), and have compared it to standard oxygen culture conditions (15% oxygen at the cell surface). Sandwich enzyme-linked immunosorbent assay (SELISA) showed a selective and progressive increase in secretion of the TGF-beta 1 isoform in response to hypoxia, up to ninefold after cultures were exposed to low oxygen for 72 h; TGF-beta 2 peptide levels were not increased. We then investigated the transcriptional regulation of the TGF-beta 1 gene in response to low and standard oxygen tensions. In the first 24-48 h, TGF-beta 1 mRNA levels decreased steadily in both oxygen environments. This mRNA decline continued for up to 72 h in standard oxygen but not in cultures exposed to low oxygen tension. At 72 h, steady-state TGF-beta 1 mRNA levels were 8 times greater in low compared to standard oxygen, and this increase was reversible upon re-exposure of fibroblast cultures to standard oxygen tension for 24 h. Elevated TGF-beta 1 m-RNA levels in both low and standard oxygen declined steadily and with the same half-life after the addition of actinomycin D, suggesting that hypoxia increased TGF-beta 1 transcription rather than mRNA stability. We conclude that low oxygen tension upregulates the synthesis of TGF-beta 1 by human dermal fibroblasts, and leads to increased secretion of this peptide.
Falanga
V
V
University of Miami School of Medicine, Department of Dermatology and Cutaneous Surgery, Florida, 33101.
Qian
S W
SW
Danielpour
D
D
Katz
M H
MH
Roberts
A B
AB
Sporn
M B
MB
D015687:Cell Hypoxia; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D012867:Skin / Q000378:metabolism*; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*; D015854:Up-Regulation
D012333:RNA, Messenger; D016212:Transforming Growth Factor beta