REGULATION OF EXTRACELLULAR MATRIX PROTEINS BY TRANSFORMING GROWTH FACTOR β1IN CULTURED PULMONARY ENDOTHELIAL CELLS

✍ Scribed by Gouri Shanker; Dan Olson; Roger Bone; Rajinder Sawhney

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 372 KB
• Volume: 23
• Category: Article
• ISSN: 1065-6995
• DOI: 10.1006/cbir.1998.0325

✦ Synopsis

Transforming growth factor beta-1 (TGF-1 ), which is present in lung tissue, has been suggested to play a role in modulating vascular cell function in vivo. The action of TGF-1 in vivo, especially at the local site of application to connective tissue, is anabolic and leads to pulmonary fibrosis and angiogenesis, strongly indicating that TGF-may have practical applications in repair of tissue injury caused by burns, trauma, or surgery. In the present study, we have used cultured bovine pulmonary artery endothelial (BPAE) cells as a model system. Expression of various proteins, including SPARC (secreted protein acidic and rich in cysteines), type IV procollagen and fibronectin (FN) was examined by radiolabeling the cells with [ 3 H]proline, immunoprecipitation with specific antibodies, and Northern blot analyses by using specific cDNA probes. Cultured cells were labeled with [ 3 H]proline for 24 h in either the absence or in the presence of TGF-1 (0-20 ng/ml). Incorporation of radioactivity was observed in a concentration-dependent manner, maximal at 5 ng/ml. Northern blot hybridization demonstrated that TGF-1 (5 ng/ml) treatment of BPAE cells caused an increase in steady-state levels of mRNA for SPARC (75%) and FN, thus, indicating a positive modulation. To determine whether TGF-1 has an effect on cell proliferation in the cultures, the incorporation of [ 3 H]thymidine into cellular nuclei was used to measure DNA replication; 5 ng/ml had an inhibitory effect (42%) on cell proliferation. Protein production by TGF-1 , surprisingly, showed decrease in SPARC levels (42%) and in contrast increased levels of FN (86%) and type IV procollagen (334%). Our results indicate that on exposure to TGF-1 , cultured BPAE cells differentially change expression of extracellular matrix proteins which may be important in remodeling of tissue and healing at sites of injury.