Main description:

Inhibin, activin, and follistatin were originally discovered as hormonal fac- tors a decade ago. Subsequent studies revealed that they are widely distrib- uted anatomically and have multiple biological functions in a wide range of cells and tissues. Since the last Symposium three years ago, there has been remarkable progress toward defining activin's roles in controlling hormone secretion, cell differentiation and proliferation, mesoderm induction in em- bryos, nerve cell survival, and promotion of bone growth. Furthermore, the characterization of activin receptors as serine and threonine kinases and the identification of intracellular mediators such as the Smads have provided key elements for the eventual understanding of signaling mechanisms for activin and the other members of the TGF-beta superfamily. The unknown in this integrative field, however, remains far greater than the known. For ex- ample, we are just beginning to exploit the recently improved activin, inhibin, and follistatin two-site assays for the evaluation of the physiological and pathophysiological functions of these proteins.
Also, we have only a rudi- mentary understanding of the mechanisms by which inhibin blocks activin, and many steps in the pathways linking the formation of ligand-receptor(s) complexes to transcriptional regulation are unclear. The aim of the Third Symposium was to bring together scientists from diverse fields to share technical and conceptual developments. The program was framed with the intention to include a wide range of timely research topics.

Contents:

1. Receptor Serine Kinases and Signaling by Activins and Inhibins.- 2. The Gene Expression of Activin Receptors in Rat Pituitary.- 3. Follistatin Physiology and Potential Mechanisms of Action in the Human.- 4. Inhibins, Activins, Follistatin, and GnRH: Regulators of Gonadotropin Subunit Gene Expression.- 5. Inhibin and Activin as Paracrine Regulators of Gonadal Function: In Vitro Model Systems.- 6. Production and Actions of Inhibin, Activin, and Follistatin in the Pituitary and Ovary.- 7. Expression of Inhibin Subunits, Follistatin, and Activin Receptors in Normal Testicular Cells and Testicular Tumors.- 8. Inhibin, Activin, and Follistatin: Observations on Their Role in the Physiology of Pregnancy.- 9. Changes of Activin A Secretion in Gestational Diseases.- 10. Two-Site Immunoassay for Native Inhibin A.- 11. Ultrasensitive Enzyme Immunoassays for Inhibins and Activins.- 12. Immunoassays for Activin and Follistatin: Results in Normal and Diseased Subjects.- 13. Circulating Inhibin.- 14. Evaluation of Matemal Serum Inhibin as a Marker for Complicated Pregnancy.- 15. Production of Inhibin-Related Peptides by Ovarian Tumors.- 16. Plasma Inhibin and Activin in Disease.- 17. Activin A: A Commitment Factor in Erythroid Differentiation.- 18. Effect of Activin A on the Formation of Pancreatic Endocrine Cells.- 19. The Role of Activin in Spermatogenesis in Fish.- 20. Control of Cell Differentiation and Morphogenesis by Activins During Early Amphibian Development.- 21. Neural Induction in the Frog Xenopus laevis.- 22. Transgenic Approaches to Study the Functions of the Transforming Growth Factor-? Superfamily Members.- 23. Activin Signaling Pathways and Their Role in Xenopus Mesoderm Formation.- 24. Activin Signal Transduction and the Role of TGF-? Superfamily in Cell Differentiation.- 25. The Role of Follistatin in Activin Signal Transduction.- 26. Transforming Growth Factor-? Receptors and Signal Transduction.- Short Communications from the Poster Session.- 27. Cytokine Inhibits Inhibin A Secretion in Cultured Rat Granulosa Cells.- 28. Mitosis and Inhibin Production in Ovarian Follicular Granulosa Cells During the Estrous Cycle of Rats.- 29. Induction of G1 Arrest by Activin A via Cooperative Modulation of Cyclin D2 and p21CIP1/WAF1 in Hybridoma Cells.- 30. Pharmacological Analysis of the Neurotrophic Effect of Activin.- 31. A Follistatin-Like Gene, mac25, as a Tumor Suppressor.- 32. Expresssion of Activin ?-Subunit and Type II Receptor Genes During Newt Spermatogenesis.- 33. Analysis of the Response of Human Embryonal Carcinoma Cells to Aetivin A.- 34. Regulation of Angiogenesis by TGF-? Superfamily.- Author Index.