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Evidence for gating roles of protein kinase A and protein kinase C in estradiol-induced luteinizing hormone receptor (lhcgr) expression in zebrafish ovarian follicle cells.

Liu KC, Ge W - PLoS ONE (2013)

Bottom Line: PKA inhibitor H89 showed reversed effects.In contrast, PKC pathway had consistent permissive effect on E2-induced lhcgr expression as evidenced by strong inhibition of E2 effect by PKC inhibitors GF109203X and Ro-31-8220 at both 3 and 24 h.One of the mechanisms by which PKA and PKC gated E2 effect might be through regulating nERs, particularly esr2a.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences and Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.

ABSTRACT
Estradiol (E2) stimulates luteinizing hormone receptor (lhcgr) expression in zebrafish follicle cells via nuclear estrogen receptors (nERs) that are likely expressed on the membrane, and lhcgr responds to E2 in a biphasic manner during 24-h treatment. These observations raise an interesting question on the signaling mechanism underlying E2 regulation, in particular the biphasic response of lhcgr expression. In the present study, we demonstrated that E2 regulation of lhcgr was significantly influenced by the activity of cAMP-PKA pathway. Activation of cAMP-PKA pathway by forskolin or db-cAMP suppressed E2-stimulated lhcgr expression in short-term (3 h) but enhanced its effect in long-term (24 h), suggesting differential roles of PKA at these two phases of lhcgr response. PKA inhibitor H89 showed reversed effects. In contrast, PKC pathway had consistent permissive effect on E2-induced lhcgr expression as evidenced by strong inhibition of E2 effect by PKC inhibitors GF109203X and Ro-31-8220 at both 3 and 24 h. One of the mechanisms by which PKA and PKC gated E2 effect might be through regulating nERs, particularly esr2a. Despite the strong influence of PKA and PKC, our data did not suggest direct mediating roles for these two pathways in E2 stimulation of lhcgr expression; yet they likely play critical gating roles in E2 signal transduction. As a follow-up study to our previous report on E2 regulation of gonadotropin receptors in the zebrafish ovary, the present study provides further evidence for the involvement of classical intracellular signal transduction pathways in E2 stimulation of lhcgr expression in the follicle cells.

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Hypothetical model showing the biphasic signaling pathways in E2-stimulated lhcgr expression in the zebrafish ovary.AC, adenylate cyclase; PKA, protein kinase A; PKC, protein kinase C; CREB, cAMP-responsive element binding protein.
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pone-0062524-g008: Hypothetical model showing the biphasic signaling pathways in E2-stimulated lhcgr expression in the zebrafish ovary.AC, adenylate cyclase; PKA, protein kinase A; PKC, protein kinase C; CREB, cAMP-responsive element binding protein.

Mentions: In summary, although we did not identify any direct mediators of E2 signaling downstream of its receptors, especially the ones responsible for the biphasic lhcgr response to E2, the current study demonstrated differential gating roles of cAMP-PKA and PKC pathways (Fig. 8). The gating role of cAMP-PKA pathway appeared to be time-dependent, which negatively modulated E2-stimulated lhcgr expression in short-term (3 h) but promoted it in long-term (24 h). The long-term effect was likely mediated by up-regulating esr2a to enhance E2 responsiveness of zebrafish follicle cells. In contrast, PKC pathway exerted a consistently positive gating role in E2-induced lhcgr expression, which also appeared to involve regulating the expression of esr2a to some extent. The present study provides strong evidence for the involvement of multiple signaling pathways in E2 stimulation of lhcgr expression in the zebrafish ovary. The exact roles and interactions of these pathways will be interesting issues for future studies.


Evidence for gating roles of protein kinase A and protein kinase C in estradiol-induced luteinizing hormone receptor (lhcgr) expression in zebrafish ovarian follicle cells.

Liu KC, Ge W - PLoS ONE (2013)

Hypothetical model showing the biphasic signaling pathways in E2-stimulated lhcgr expression in the zebrafish ovary.AC, adenylate cyclase; PKA, protein kinase A; PKC, protein kinase C; CREB, cAMP-responsive element binding protein.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643932&req=5

pone-0062524-g008: Hypothetical model showing the biphasic signaling pathways in E2-stimulated lhcgr expression in the zebrafish ovary.AC, adenylate cyclase; PKA, protein kinase A; PKC, protein kinase C; CREB, cAMP-responsive element binding protein.
Mentions: In summary, although we did not identify any direct mediators of E2 signaling downstream of its receptors, especially the ones responsible for the biphasic lhcgr response to E2, the current study demonstrated differential gating roles of cAMP-PKA and PKC pathways (Fig. 8). The gating role of cAMP-PKA pathway appeared to be time-dependent, which negatively modulated E2-stimulated lhcgr expression in short-term (3 h) but promoted it in long-term (24 h). The long-term effect was likely mediated by up-regulating esr2a to enhance E2 responsiveness of zebrafish follicle cells. In contrast, PKC pathway exerted a consistently positive gating role in E2-induced lhcgr expression, which also appeared to involve regulating the expression of esr2a to some extent. The present study provides strong evidence for the involvement of multiple signaling pathways in E2 stimulation of lhcgr expression in the zebrafish ovary. The exact roles and interactions of these pathways will be interesting issues for future studies.

Bottom Line: PKA inhibitor H89 showed reversed effects.In contrast, PKC pathway had consistent permissive effect on E2-induced lhcgr expression as evidenced by strong inhibition of E2 effect by PKC inhibitors GF109203X and Ro-31-8220 at both 3 and 24 h.One of the mechanisms by which PKA and PKC gated E2 effect might be through regulating nERs, particularly esr2a.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences and Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.

ABSTRACT
Estradiol (E2) stimulates luteinizing hormone receptor (lhcgr) expression in zebrafish follicle cells via nuclear estrogen receptors (nERs) that are likely expressed on the membrane, and lhcgr responds to E2 in a biphasic manner during 24-h treatment. These observations raise an interesting question on the signaling mechanism underlying E2 regulation, in particular the biphasic response of lhcgr expression. In the present study, we demonstrated that E2 regulation of lhcgr was significantly influenced by the activity of cAMP-PKA pathway. Activation of cAMP-PKA pathway by forskolin or db-cAMP suppressed E2-stimulated lhcgr expression in short-term (3 h) but enhanced its effect in long-term (24 h), suggesting differential roles of PKA at these two phases of lhcgr response. PKA inhibitor H89 showed reversed effects. In contrast, PKC pathway had consistent permissive effect on E2-induced lhcgr expression as evidenced by strong inhibition of E2 effect by PKC inhibitors GF109203X and Ro-31-8220 at both 3 and 24 h. One of the mechanisms by which PKA and PKC gated E2 effect might be through regulating nERs, particularly esr2a. Despite the strong influence of PKA and PKC, our data did not suggest direct mediating roles for these two pathways in E2 stimulation of lhcgr expression; yet they likely play critical gating roles in E2 signal transduction. As a follow-up study to our previous report on E2 regulation of gonadotropin receptors in the zebrafish ovary, the present study provides further evidence for the involvement of classical intracellular signal transduction pathways in E2 stimulation of lhcgr expression in the follicle cells.

Show MeSH
Related in: MedlinePlus