Activin A Binds to Perlecan through Its Pro-region That Has Heparin/Heparan Sulfate Binding Activity |
| |
Authors: | Shaoliang Li Chisei Shimono Naoko Norioka Itsuko Nakano Tetsuo Okubo Yoshiko Yagi Maria Hayashi Yuya Sato Hitomi Fujisaki Shunji Hattori Nobuo Sugiura Koji Kimata Kiyotoshi Sekiguchi |
| |
Affiliation: | From the ‡Laboratory of Extracellular Matrix Biochemistry, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.;the §Nippi Research Institute of Biomatrix, 520-11 Kuwabara, Toride, Ibaraki 302-0017, Japan, and ;the ¶Institute for Molecular Science of Medicine, Aichi Medical University, Nagakute, Aichi 480-1195, Japan |
| |
Abstract: | Activin A, a member of the transforming growth factor-β family, plays important roles in hormonal homeostasis and embryogenesis. In this study, we produced recombinant human activin A and examined its abilities to bind to extracellular matrix proteins. Recombinant activin A expressed in 293-F cells was purified as complexes of mature dimeric activin A with its pro-region. Among a panel of extracellular matrix proteins tested, recombinant activin A bound to perlecan and agrin, but not to laminins, nidogens, collagens I and IV, fibronectin, and nephronectin. The binding of recombinant activin A to perlecan was inhibited by heparin and high concentrations of NaCl and abolished by heparitinase treatment of perlecan, suggesting that activin A binds to the heparan sulfate chains of perlecan. In support of this possibility, recombinant activin A was capable of directly binding to heparin and heparan sulfate chains. Site-directed mutagenesis of recombinant activin A revealed that clusters of basic amino acid residues, Lys259-Lys263 and Lys270-Lys272, in the pro-region were required for binding to perlecan. Interestingly, deletion of the peptide segment Lys259-Gly277 containing both basic amino acid clusters from the pro-region did not impair the activity of activin A to stimulate Smad-dependent gene expressions, although it completely ablated the perlecan-binding activity. The binding of activin A to basement membrane heparan sulfate proteoglycans through the basic residues in the pro-region was further confirmed by in situ activin A overlay assays using frozen tissue sections. Taken together, the present results indicate that activin A binds to heparan sulfate proteoglycans through its pro-region and thereby regulates its localization within tissues. |
| |
Keywords: | Basement Membrane, Bone Morphogenetic Protein (BMP), Extracellular Matrix, Extracellular Matrix Proteins, Glycosaminoglycan, Growth Factors, Heparan Sulfate, Transforming Growth Factor β (TGFβ ) |
|
|