An active site of transforming growth factor-beta(1) for growth inhibition and stimulation.
Transforming growth factor-beta (TGF-beta) is a bifunctional growth regulator. It inhibits growth of many cell types, including epithelial cells, but stimulates growth of others (e.g. fibroblasts). The active site on the TGF-beta molecule, which mediates its growth regulatory activity, has not been defined. Here, we show that antibody to a TGF-beta(1) peptide containing the motif WSLD (52nd to 55th amino acid residues) completely blocked both (125)I-TGF-beta(1) binding to TGF-beta receptors and TGF-beta(1)-induced growth inhibition in mink lung epithelial cells. Site-directed mutagenesis analysis revealed that the replacement of Trp(52) and Asp(55) by alanine residues diminished the growth inhibitory activity of TGF-beta(1) by approximately 90%. Finally, while wild-type TGF-beta(1) was able to stimulate growth of transfected NIH 3T3 cells, the double mutant TGF-beta(1) W52A/D55A was much less active. These results support the hypothesis that the WSLD motif is an active site of TGF-beta(1), which is important for growth inhibition of epithelial cells and growth stimulation of fibroblasts.
Huang
S S
SS
Departments of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA. huangjs@slu.edu
Zhou
M
M
Johnson
F E
FE
Shieh
H S
HS
Huang
J S
JS
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001665:Binding Sites; D016466:CHO Cells; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D006224:Cricetinae; D004247:DNA / Q000096:biosynthesis; D004847:Epithelial Cells; D000939:Epitopes / Q000737:chemistry; D007700:Kinetics; D008168:Lung; D008907:Mink; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D017433:Protein Structure, Secondary; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D013552:Swine; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000737:chemistry* / Q000494:pharmacology / Q000502:physiology*
D000906:Antibodies; D000939:Epitopes; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D004247:DNA