Merck, H4666-10UG, Activin A human

Biochem/physiol Actions
Activin-A participates in a diverse array of functions that include; hypothalamic/pituitary/gonadal hormone secretion, insulin secretion; cell growth, differentiation and survival (apoptosis); embryonic patterning and development; wound healing; and inflammation/immune response. It was initially identified as a follicle stimulating hormone/FSH-releasing protein (gonadal hormone), Ling N, et al. (1986) and erythroid differentiation factor (EDF), Schwall R, et al. (1989). The FSH activity is linked to an increase in the population of pituitary gonadotrophs by Katayama T, et al. (1990). In addition to gonadotrophs, activin-A also modifies somatotrophs and lactotrophs, Kitaoka, et al. (1988).

Activin-A stimulates glycogenolysis in isolated rat hepatocytes, Mine T ET. al. (1989) and elevates insulin release from rat pancreatic islets, Verspohl EJ et al. (1993). Activin-A stimulates insulin secretion in rat pancreatic islets, Totsuka Y, et al. (1988).

Follistatin, an activin-binding protein, is a principle regulator of activin activity, de Winter JP, et al. (1996); however during embryogenesis, Cripto is an important noncompetitive activin antagonist that facilitates Nodal signaling, Kelber JA, et al. (2008).

A role for activin-A as a regulator of cell proliferation was recognized by Gonzalez-Manchon C and Vale W. (1989); wherein Act-A inhibited the growth of and induced morphological changes in CHO-KI cells in culture, in a way similar to but less potent than TGF-β.

Activin A is involved with the entire process of embryo development from germ cells thru embryonic development to adult tissues. It stimulates spermatogonial proliferation in germ-Sertoli cell cocultures, Mather JP, et al. (1990) and is a maturation factor for oocytes, Itoh M, et al. (1990). Activin A promotes proliferation of human luteinized preovulation granulose cells (ovarian granulose cells), Rabinovici J, et al. (1990).
Analysis Note
The specific activity was determined by the dose-dependent inhibition of proliferation of the MPC-11 cell line (mouse plasmocytoma cell line).
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