title: Expression of activin receptors, follistatin and betaglycan by human endometrial stromal cells; consistent with a role for activins during decidualization.
abstract: Decidualization of the human endometrium is critical for implantation, but the mechanisms involved are largely unknown. Activin subunits are expressed in endometrium during decidualization. From its known actions in cell differentiation and tissue remodelling, we hypothesized that activin A is involved in the paracrine regulation of decidualization. We examined the expression of activin receptors (ActRs) by semi-quantitative and real-time RT-PCR. mRNA for all ActR subtypes (Ia, Ib, IIa and IIb) was detected in endometrium, with maximal expression in the early secretory phase and in early pregnancy. ActR protein was localized exclusively to stromal and endothelial cells. This expression pattern was confirmed by in-situ hybridization. Activin bioavailability is locally regulated by its binding protein, follistatin, and also by the antagonist, inhibin. Inhibin competition for ActRII binding is enhanced by the binding protein, betaglycan. Follistatin and betaglycan were also detected in the endometrium, localized to stromal and epithelial cells. This co-expression of activin subunits, receptors and binding proteins indicates that stromal cells are capable of responding to activin, and that there is tight local regulation of activin action within the endometrium. As activin production is up-regulated in decidual cells, this provides further evidence for an involvement of activins during stromal cell decidualization.
authors.affiliation: Prince Henry's Institute of Medical Research, P.O.Box 5152, Clayton, Victoria 3168, Australia. rebecca.jones@med.monash.edu.au
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Jones
authors.forename: Lois A
authors.initials: LA
authors.lastname: Salamonsen
authors.forename: Yi Chen
authors.initials: YC
authors.lastname: Zhao
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Ethier
authors.forename: Ann E
authors.initials: AE
authors.lastname: Drummond
authors.forename: Jock K
authors.initials: JK
authors.lastname: Findlay
mesh_terms: D029404:Activin Receptors / Q000096:biosynthesis* / Q000502:physiology; D028341:Activins / Q000096:biosynthesis* / Q000378:metabolism; D000328:Adult; D003656:Decidua / Q000502:physiology*; D004717:Endometrium / Q000166:cytology / Q000502:physiology*; D005260:Female; D038681:Follistatin; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007265:Inhibins / Q000378:metabolism; D011509:Proteoglycans / Q000096:biosynthesis* / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis* / Q000378:metabolism; D017154:Stromal Cells / Q000502:physiology
chemical_list: D038681:Follistatin; D011509:Proteoglycans; D018125:Receptors, Transforming Growth Factor beta; D028341:Activins; C071736:betaglycan; D007265:Inhibins; D029404:Activin Receptors