Non-genomic actions of estrogen: physiological implications and signalling pathways
Thais F.G. Lucas, Erica R. Siu; Maria F.M. Lazari, Catarina S. Porto - Section of Experimental
Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil,
04044020.
17-estradiol (E2) plays an important role in the development, differentiation and growth of the
male reproductive system by binding to estrogen receptors (ER and ER) (see 1-4 for reviews). Our
previous studies showed that the effect of E2 on Sertoli cell (Sc) function involves: translocation of the
ER and ER to the plasma membrane mediated by the nonreceptor tyrosine kinase Src, activation of
the MAPK (Erk1/2) and cell proliferation (5). In addition, E2 or antiestrogen ICI 182,780 (ICI) can
also rapidly activate Erk1/2 after downregulation of both ERs in Sc, through unidentified ER-mediated
mechanisms. The rapid action of estrogen can be mediated by membrane translocation of ERs or
through proteins other than ERs, such as G-protein coupled receptor (GPR30), as previously shown in
different cells (see 6-8 for reviews). In the present study was shown the expression of GPR30 in
cultured Sertoli cells from immature rats and the role of E2 and ICI to induce Erk1/2 activation and Sc
proliferation. RT-PCR assays detected transcript of the expected size (662 pb) for GPR30. E2 (10-10M,
350C) induced a rapid and transient increase in the phosphorylation state of Erk1/2. Peak Erk1/2
phosphorylation levels occurred at 10 min (7- to 12-fold increase) with Erk1/2 activity returning to
basal levels by 15-30 min. Cells treated with cAMP-dependent protein kinase A inhibitor H89 (20 M,
2 h) maintained elevated levels of Erk1/2 activity for an extendent period of time (more than 30 min)
after E2 stimulation. Erk1/2 activation in Sc could also be achieved using ICI (10-9M). An increase in
cell proliferation was observed after these treatments. The activation of Erk1/2 and cell proliferation
induced by either E2 or ICI were blocked by pre-treatment of Sc with pertussis toxin (PTX, 100 µM,
16 h) or Src family tyrosine kinase inhibitor PP2 (5 nM, 30 min). EGF receptor kinase inhibitor AG
1478 (50 µM, 15 min), metalloprotease inhibitor GM 6001 (200 nM, 30 min) and MEK1/2 inhibitor
U0126 (100 M, 30 min) also blocked Erk1/2 activation. Taken together, these data suggest that E2GPR30 signaling occurs through a PTX-sensitive pathway and requires Src-related tyrosine kinase
activity. The activation of Erk1/2 induced by E2 or ICI is dependent upon transactivation of the EGF
receptor via release of heparin-bound EGF. Furthermore, the activation of cAMP-dependent PKA is
required to restore E2-induced Erk1/2 activity to basal levels.
Supported by FAPESP, PRONEX/FAPESP, CNPq.
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(5) Lucas et al., 2006 Abstract The Endocrine Society’s 88 th Annual Meeting., pp 718
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