posted on 2017-01-09, 00:00authored byS.C. Baumgarten, S.M. Convissar, M.A. Fierro, N.J. Winston, B. Scoccia, C. Stocco
Context: FSH is routinely administered to in vitro fertilization patients to induce folliclematuration.
During this process, granulosa cells differentiate and acquire specific functional characteristics that
are required to coordinate ovulation and oocyte maturation.
Objective: The objective of the study was to gain insight into the molecular mechanisms regulating
human granulosa cell differentiation.
Design, Setting, Patients, and Interventions: Cumulus and mural granulosa cells were isolated
from the follicular aspirates of in vitro fertilization patients and analyzed immediately or cultured
in serum-free media in the presence of FSH, IGFs, or an inhibitor of type I IGF receptor (IGF1R)
activity.
Main outcome:We quantified the mRNA and protein levels of steroidogenic enzymes, components
of the IGF system, and gonadotropin receptors; measured 17-estradiol levels; and examined the
activation of intracellular signaling pathways to assess the granulosa cell differentiation as well as
the FSH and IGF actions in both cumulus and mural cells.
Results: In freshly isolated cells, LH receptor (Lhr) and steroidogenic acute regulator (Star) were
expressed at lower levels in cumulus than mural cells, whereas FSH receptor (Fshr) and anti-Müllerian
hormone (Amh) were expressed at higher levels in cumulus than mural cells. In vitro, the
expression of Igf2, the differentiation markers Lhr, Star, and Cyp19a1 (aromatase) as well as 17-
estradiol production remained low in untreated cumulus cells but increased significantly after FSH
treatment. Strikingly, this stimulatory effect of FSH was abolished by the inhibition of IGF1R activity.
FSH-induced activation of v-akt murine thymoma viral oncogene homolog 3 (AKT) required
IGF1R activity, and overexpression of constitutively active AKT rescued the induction of differentiation
markers and 17-estradiol production by FSH in the presence of the IGF1R inhibitor.
Conclusions: The cumulus cell response to FSH resembles the differentiation of preantral to preovulatory
granulosa cells. This differentiation program requires IGF1R activity and subsequent AKT
activation. (J Clin Endocrinol Metab 99: 2995–3004, 2014)
Funding
This work was supported by National Institutes of Health
Grant R01HD057110 (to C.S.); S.C.B. and S.M.C. are supported
by National Institutes of Health Training Grant
T32HL07692.
History
Publisher Statement
This is a copy of an article published in the Journal of Clinical Endocrinology & Metabolism. Published by the Endocrine Society. jcem.endojournals.org