Abstract
The present study investigated the activation of mitogen activated protein kinases (MAPKs) by a GnRH agonist (GnRHa) in human granulosa-luteal cells (hGLCs). The phosphorylation state of p44 and p42 MAPK was examined using antibodies that distinguish phosphop44/42 MAPK (Thr202/Tyr204) from total p44/42 MAPK (activated plus inactivated). Activation of MAPK by GnRHa was observed within 5 min and was sustained for 60 min after treatment. GnRHa stimulated MAPK activation in a dose-dependent manner, with maximum stimulation (6.7-fold over basal levels) at 10-7 M. Pretreatment with a protein kinase C (PKC) inhibitor, GF109203X, completely blocked GnRHa-induced MAPK activation. In addition, pretreatment with a PKC activator, phorbol-12-myristate 13-acetate, potentiated GnRH-induced MAPK activation. These results indicate that GnRHa stimulates MAPK activation through a PKC-dependent pathway in hGLCs, possibly coupled to Gqα protein. MAPK activation was also observed in response to 8-bromo-cAMP or cholera toxin, but not pertussis toxin. Forskolin (50 μM) substantially stimulated a rapid cAMP accumulation, whereas GnRHa (10-7 M) or pertussis toxin (100 mg/ml) did not affect basal intracellular cAMP levels. Cotreatment of GnRHa (10-7 M) did not attenuate forskolin- or hCG-stimulated cAMP accumulation. These results suggest that the GnRH receptor is probably not coupled to Gsα or Giα in hGLCs. Finally, GnRHa (10-7 M) stimulated a significant increase in Elk-1 phosphorylation and c-fos messenger RNA expression, as revealed by an in vitro kinase assay and Northern blot analysis, respectively. These results clearly demonstrate that GnRH activates the MAPK cascade through a PKC-dependent pathway in the human ovary.
| Original language | English |
|---|---|
| Pages (from-to) | 671-679 |
| Number of pages | 9 |
| Journal | Endocrinology |
| Volume | 142 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2001 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
Cite this
Stimulation of mitogen-activated protein kinase by gonadotropin-releasing hormone in human granulosa-luteal cells. / Sung Keun Kang, Keun Kang; Tai, C. J.; Nathwani, P. S.; Choi, K. C.; Leung, P. C K.
In: Endocrinology, Vol. 142, No. 2, 2001, p. 671-679.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Stimulation of mitogen-activated protein kinase by gonadotropin-releasing hormone in human granulosa-luteal cells
AU - Sung Keun Kang, Keun Kang
AU - Tai, C. J.
AU - Nathwani, P. S.
AU - Choi, K. C.
AU - Leung, P. C K
PY - 2001
Y1 - 2001
N2 - The present study investigated the activation of mitogen activated protein kinases (MAPKs) by a GnRH agonist (GnRHa) in human granulosa-luteal cells (hGLCs). The phosphorylation state of p44 and p42 MAPK was examined using antibodies that distinguish phosphop44/42 MAPK (Thr202/Tyr204) from total p44/42 MAPK (activated plus inactivated). Activation of MAPK by GnRHa was observed within 5 min and was sustained for 60 min after treatment. GnRHa stimulated MAPK activation in a dose-dependent manner, with maximum stimulation (6.7-fold over basal levels) at 10-7 M. Pretreatment with a protein kinase C (PKC) inhibitor, GF109203X, completely blocked GnRHa-induced MAPK activation. In addition, pretreatment with a PKC activator, phorbol-12-myristate 13-acetate, potentiated GnRH-induced MAPK activation. These results indicate that GnRHa stimulates MAPK activation through a PKC-dependent pathway in hGLCs, possibly coupled to Gqα protein. MAPK activation was also observed in response to 8-bromo-cAMP or cholera toxin, but not pertussis toxin. Forskolin (50 μM) substantially stimulated a rapid cAMP accumulation, whereas GnRHa (10-7 M) or pertussis toxin (100 mg/ml) did not affect basal intracellular cAMP levels. Cotreatment of GnRHa (10-7 M) did not attenuate forskolin- or hCG-stimulated cAMP accumulation. These results suggest that the GnRH receptor is probably not coupled to Gsα or Giα in hGLCs. Finally, GnRHa (10-7 M) stimulated a significant increase in Elk-1 phosphorylation and c-fos messenger RNA expression, as revealed by an in vitro kinase assay and Northern blot analysis, respectively. These results clearly demonstrate that GnRH activates the MAPK cascade through a PKC-dependent pathway in the human ovary.
AB - The present study investigated the activation of mitogen activated protein kinases (MAPKs) by a GnRH agonist (GnRHa) in human granulosa-luteal cells (hGLCs). The phosphorylation state of p44 and p42 MAPK was examined using antibodies that distinguish phosphop44/42 MAPK (Thr202/Tyr204) from total p44/42 MAPK (activated plus inactivated). Activation of MAPK by GnRHa was observed within 5 min and was sustained for 60 min after treatment. GnRHa stimulated MAPK activation in a dose-dependent manner, with maximum stimulation (6.7-fold over basal levels) at 10-7 M. Pretreatment with a protein kinase C (PKC) inhibitor, GF109203X, completely blocked GnRHa-induced MAPK activation. In addition, pretreatment with a PKC activator, phorbol-12-myristate 13-acetate, potentiated GnRH-induced MAPK activation. These results indicate that GnRHa stimulates MAPK activation through a PKC-dependent pathway in hGLCs, possibly coupled to Gqα protein. MAPK activation was also observed in response to 8-bromo-cAMP or cholera toxin, but not pertussis toxin. Forskolin (50 μM) substantially stimulated a rapid cAMP accumulation, whereas GnRHa (10-7 M) or pertussis toxin (100 mg/ml) did not affect basal intracellular cAMP levels. Cotreatment of GnRHa (10-7 M) did not attenuate forskolin- or hCG-stimulated cAMP accumulation. These results suggest that the GnRH receptor is probably not coupled to Gsα or Giα in hGLCs. Finally, GnRHa (10-7 M) stimulated a significant increase in Elk-1 phosphorylation and c-fos messenger RNA expression, as revealed by an in vitro kinase assay and Northern blot analysis, respectively. These results clearly demonstrate that GnRH activates the MAPK cascade through a PKC-dependent pathway in the human ovary.
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U2 - 10.1210/en.142.2.671
DO - 10.1210/en.142.2.671
M3 - Article
VL - 142
SP - 671
EP - 679
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 2
ER -