Endocrinology, Vol 132, 431-443, Copyright © 1993 by Endocrine Society

ARTICLES

Identification and characterization of binding proteins for inhibin and activin in human serum and follicular fluids

LA Krummen, TK Woodruff, G DeGuzman, ET Cox, DL Baly, E Mann, S Garg, WL Wong, P Cossum and JP Mather
Genetech, Inc., South San Francisco, California 94080.

Inhibins and activins are produced by a variety of tissues and may have important endocrine and paracrine roles in development, reproduction, and hematopoiesis. However, little is known regarding the physical properties or concentrations of inhibin and activin in biological fluids. Binding proteins for inhibin or activin in serum or at production or target sites may have important implications for restricting the bioactivity of these hormones and may alter the immunoreactivity of these molecules in biological fluids. The objective of this study was to identify inhibin- and activin-binding proteins in human serum (HS) and follicular fluid (hFF) and determine the ability of these proteins to alter biological or immunological activity. In HS, [125I]activin and inhibin bound to a protein identified as alpha 2- macroglobulin (alpha 2M) using three criteria: 1) [125I]inhibin and activin bind purified alpha 2M, but not several other serum proteins tested; 2) complexes formed by [125I]inhibin and activin in HS and in the presence of purified alpha 2M elute with similar retention times on HPLC; and 3) preadsorption of HS with alpha 2M antiserum inhibits inhibin and activin binding to this protein while antiserum directed against follistatin or other serum proteins had no effect. A small amount of a lower mol wt [125I]activin-follistatin complex was also found in HS. This complex eluted with a retention time similar to that of activin bound to purified porcine follistatin. Binding of inhibin to follistatin could not be detected in HS. In contrast, follistatin was the major binding protein of both activin and inhibin in hFF. Concentrations up to 100 micrograms/ml purified alpha 2M had no effect on the bioactivity or immunoreactivity of either inhibin or activin. In contrast, follistatin inhibited both activin-stimulated pituitary FSH release and K562 hemoglobin production as well as antiserum binding in a specific activin-A immunoassay. Follistatin did not interfere with inhibin immunodetection. These data indicate that two inhibin- and activin-binding proteins are present in different relative amounts in HS and hFF, alpha 2M, the primary binding protein in HS, did not alter inhibin or activin bio- or immunoactivity under the conditions of these experiments, while follistatin, the major binding protein in hFF, may mask activin's bio- and immunoactivities.

This article has been cited by other articles:

				J. B. Hoffman, A. P. Benson, V. L. Christensen, B. D. Fairchild, and A. J. Davis Follicular Development and Expression of the Messenger Ribonucleic Acid for the Inhibin/Activin Subunits in Two Genetic Lines of Turkey Hens that Differ in Total Egg Production Poult. Sci., May 1, 2007; 86(5): 944 - 952. [Abstract] [Full Text] [PDF]

				T. R. Kumar Too Many Follistatins: Racing Inside and Getting Out of the Cell Endocrinology, December 1, 2005; 146(12): 5048 - 5051. [Full Text] [PDF]

				N. Safwat, J. Ninomiya-Tsuji, A. J. Gore, and W. L. Miller Transforming Growth Factor {beta}-Activated Kinase 1 Is a Key Mediator of Ovine Follicle-Stimulating Hormone {beta}-Subunit Expression Endocrinology, November 1, 2005; 146(11): 4814 - 4824. [Abstract] [Full Text] [PDF]

				A. L. Schneyer, Q. Wang, Y. Sidis, and P. M. Sluss Differential Distribution of Follistatin Isoforms: Application of a New FS315-Specific Immunoassay J. Clin. Endocrinol. Metab., October 1, 2004; 89(10): 5067 - 5075. [Abstract] [Full Text] [PDF]

				J. J. Hill, Y. Qiu, R. M. Hewick, and N. M. Wolfman Regulation of Myostatin in Vivo by Growth and Differentiation Factor-Associated Serum Protein-1: A Novel Protein with Protease Inhibitor and Follistatin Domains Mol. Endocrinol., June 1, 2003; 17(6): 1144 - 1154. [Abstract] [Full Text] [PDF]

				M. I. Suszko, D. J. Lo, H. Suh, S. A. Camper, and T. K. Woodruff Regulation of the Rat Follicle-Stimulating Hormone {beta}-Subunit Promoter by Activin Mol. Endocrinol., March 1, 2003; 17(3): 318 - 332. [Abstract] [Full Text] [PDF]

				J. J. Hill, M. V. Davies, A. A. Pearson, J. H. Wang, R. M. Hewick, N. M. Wolfman, and Y. Qiu The Myostatin Propeptide and the Follistatin-related Gene Are Inhibitory Binding Proteins of Myostatin in Normal Serum J. Biol. Chem., October 18, 2002; 277(43): 40735 - 40741. [Abstract] [Full Text] [PDF]

				M. Abe, Y. Shintani, Y. Eto, K. Harada, M. Kosaka, and T. Matsumoto Potent induction of activin A secretion from monocytes and bone marrow stromal fibroblasts by cognate interaction with activated T cells J. Leukoc. Biol., August 1, 2002; 72(2): 347 - 352. [Abstract] [Full Text] [PDF]

				Y.-G. Chen, H. M. Lui, S.-L. Lin, J. M. Lee, and S.-Y. Ying Regulation of Cell Proliferation, Apoptosis, and Carcinogenesis by Activin Experimental Biology and Medicine, February 1, 2002; 227(2): 75 - 87. [Abstract] [Full Text] [PDF]

				G. P. Risbridger, J. F. Schmitt, and D. M. Robertson Activins and Inhibins in Endocrine and Other Tumors Endocr. Rev., December 1, 2001; 22(6): 836 - 858. [Abstract] [Full Text] [PDF]

				A. J. Davis, C. F. Brooks, and P. A. Johnson Follicle-Stimulating Hormone Regulation of Inhibin {{alpha}}- and {beta}B-Subunit and Follistatin Messenger Ribonucleic Acid in Cultured Avian Granulosa Cells Biol Reprod, January 1, 2001; 64(1): 100 - 106. [Abstract] [Full Text]

				N. A. Klein, D. E. Battaglia, T. K. Woodruff, V. Padmanabhan, L. C. Giudice, W. J. Bremner, and M. R. Soules Ovarian Follicular Concentrations of Activin, Follistatin, Inhibin, Insulin-Like Growth Factor I (IGF-I), IGF-II, IGF-Binding Protein-2 (IGFBP-2), IGFBP-3, and Vascular Endothelial Growth Factor in Spontaneous Menstrual Cycles of Normal Women of Advanced Reproductive Age J. Clin. Endocrinol. Metab., December 1, 2000; 85(12): 4520 - 4525. [Abstract] [Full Text]

				H. Chong, S. A. Pangas, D. J. Bernard, E. Wang, J. Gitch, W. Chen, L. B. Draper, E. T. Cox, and T. K. Woodruff Structure and Expression of a Membrane Component of the Inhibin Receptor System Endocrinology, July 1, 2000; 141(7): 2600 - 2607. [Abstract] [Full Text] [PDF]

				S. J. Winters and T. M. Plant Partial Characterization of Circulating Inhibin-B and Pro-{alpha}C During Development in the Male Rhesus Monkey Endocrinology, December 1, 1999; 140(12): 5497 - 5504. [Abstract] [Full Text]

				J. R. McFarlane, L. M. Foulds, A. E. O’Connor, D. J. Phillips, G. Jenkin, M. T. W. Hearn, and D. M. de Kretser Uterine Milk Protein, a Novel Activin-Binding Protein, Is Present in Ovine Allantoic Fluid Endocrinology, October 1, 1999; 140(10): 4745 - 4752. [Abstract] [Full Text]

				R. Hertan, P. G. Farnworth, K. L. Fitzsimmons, and D. M. Robertson Identification of High Affinity Binding Sites for Inhibin on Ovine Pituitary Cells in Culture Endocrinology, January 1, 1999; 140(1): 6 - 12. [Abstract] [Full Text]

				E. Y. Wang, L. B. Draper, E. Lee, A. Polak, P. Sluss, J. Weiss, and T. K. Woodruff Identification of Naturally Occurring Follistatin Complexes in Human Biological Fluids Biol Reprod, January 1, 1999; 60(1): 8 - 13. [Abstract] [Full Text]

				N. E. Reame, T. L. Wyman, D. J. Phillips, D. M. de Kretser, and V. Padmanabhan Net Increase in Stimulatory Input Resulting from a Decrease in Inhibin B and an Increase in Activin A May Contribute in Part to the Rise in Follicular Phase Follicle-Stimulating Hormone of Aging Cycling Women J. Clin. Endocrinol. Metab., September 1, 1998; 83(9): 3302 - 3307. [Abstract] [Full Text]

				A. J. Davis and P. A. Johnson Expression Pattern of Messenger Ribonucleic Acid for Follistatin and the Inhibin/Activin Subunits during Follicular and Testicular Development in Gallus domesticus Biol Reprod, August 1, 1998; 59(2): 271 - 277. [Abstract] [Full Text]

				D. S. McConnell, Q. Wang, P. M. Sluss, N. Bolf, R. H. Khoury, A. L. Schneyer, A. R. Midgley Jr., N. E. Reame, W. F. Crowley Jr., and V. Padmanabhan A Two-Site Chemiluminescent Assay for Activin-Free Follistatin Reveals That Most Follistatin Circulating in Men and Normal Cycling Women Is in an Activin-Bound State J. Clin. Endocrinol. Metab., March 1, 1998; 83(3): 851 - 858. [Abstract] [Full Text]

				N. Di Simone, H. A. Hall, C. Welt, and A. L. Schneyer Activin Regulates {beta}A-Subunit and Activin Receptor Messenger Ribonucleic Acid and Cellular Proliferation in Activin-Responsive Testicular Tumor Cells Endocrinology, March 1, 1998; 139(3): 1147 - 1155. [Abstract] [Full Text] [PDF]

				L. Gnessi, A. Fabbri, and G. Spera Gonadal Peptides as Mediators of Development and Functional Control of the Testis: An Integrated System with Hormones and Local Environment Endocr. Rev., August 1, 1997; 18(4): 541 - 609. [Abstract] [Full Text] [PDF]

				S. S. Majumdar, S. J. Winters, and T. M. Plant A Study of the Relative Roles of Follicle-Stimulating Hormone and Luteinizing Hormone in the Regulation of Testicular Inhibin Secretion in the Rhesus Monkey (Macaca mulatta) Endocrinology, April 1, 1997; 138(4): 1363 - 1373. [Abstract] [Full Text] [PDF]

				K. Tsuchida, K. Y. Arai, Y. Kuramoto, N. Yamakawa, Y. Hasegawa, and H. Sugino Identification and Characterization of a Novel Follistatin-like Protein as a Binding Protein for the TGF-beta Family J. Biol. Chem., December 22, 2000; 275(52): 40788 - 40796. [Abstract] [Full Text] [PDF]