Sequential activation of phospholipase-C and -D in agonist-stimulated gonadotrophs

Lixin Zheng, Stanko S. Stojilkovic, L. Hunyady, Lazar Z. Krsmanovic, Kevin J. Catt

Research output: Contribution to journalArticle

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Abstract

The contributions of phospholipase-C and -D to diacylglycerol (DG) formation during agonist-induced cell signaling were investigated in rat pituitary cells and αT3-1 gonadotrophs. In both cell types, GnRH caused a biphasic increase in DG formation, with an initial spike within 60 sec, followed by a larger and sustained rise to reach a second peak after 15 min of stimulation. Both phases of DG production were temporally correlated with inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] formation, consistent with the dependence of DG formation on phospholipase-C-mediated phosphoinositide hydrolysis. However, the ability of GnRH to stimulate phosphatidylethanol (PEt) in the presence of ethanol suggested that phospholipase-D may also participate in DG formation. Two inhibitors of phospholipase-C-dependent phosphoinositide hydrolysis. U73122 and neomycin sulfate, reduced the PEt as well as the Ins(1,4,5)P3 response to GnRH, indicating that phospholipase-D is activated during phospholipase-C-dependent signaling in pituitary gonadotrophs. The production of both DG and PEt was increased by treatment with the active phorbol ester phorbol 12-myristate 13-acetate (PMA), but not with inactive 4α-phorbol 13-didecanoate, indicating that stimulation of protein kinase-C leads to activation of phospholipase-D. In accord with this, GnRH- and PMA-induced elevations of DG and PEt production were attenuated or abolished in protein kinase-C-depleted cells. In contrast, short and long term stimulation with PMA had no effect on basal inositol phosphate production. Also, GnRH-induced inositol phosphate production was not affected by protein kinase-C depletion. Finally, U73122 and neomycin sulfate did not inhibit PMA-induced PEt formation. These data indicate that GnRH activates a dual phospholipase pathway in a sequential and synchronized manner; phospholipase-C initiates the biphasic increase in Ins(1,4,5)P3 and DG formation, and protein kinase-C mediates the integration of phospholipase-D into the signaling response during the sustained phase of agonist stimulation.

Original languageEnglish
Pages (from-to)1446-1454
Number of pages9
JournalEndocrinology
Volume134
Issue number3
DOIs
Publication statusPublished - Mar 1994

Fingerprint

Gonadotrophs
Phospholipase D
Diglycerides
Type C Phospholipases
Gonadotropin-Releasing Hormone
Protein Kinase C
Acetates
Phosphoinositide Phospholipase C
Inositol Phosphates
Neomycin
Hydrolysis
Diacylglycerol Kinase
Inositol 1,4,5-Trisphosphate
Phospholipases
Phorbol Esters
Ethanol
phosphatidylethanol
phorbol-12-myristate

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Sequential activation of phospholipase-C and -D in agonist-stimulated gonadotrophs. / Zheng, Lixin; Stojilkovic, Stanko S.; Hunyady, L.; Krsmanovic, Lazar Z.; Catt, Kevin J.

In: Endocrinology, Vol. 134, No. 3, 03.1994, p. 1446-1454.

Research output: Contribution to journalArticle

Zheng, L, Stojilkovic, SS, Hunyady, L, Krsmanovic, LZ & Catt, KJ 1994, 'Sequential activation of phospholipase-C and -D in agonist-stimulated gonadotrophs', Endocrinology, vol. 134, no. 3, pp. 1446-1454. https://doi.org/10.1210/en.134.3.1446
Zheng, Lixin ; Stojilkovic, Stanko S. ; Hunyady, L. ; Krsmanovic, Lazar Z. ; Catt, Kevin J. / Sequential activation of phospholipase-C and -D in agonist-stimulated gonadotrophs. In: Endocrinology. 1994 ; Vol. 134, No. 3. pp. 1446-1454.
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AU - Catt, Kevin J.

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N2 - The contributions of phospholipase-C and -D to diacylglycerol (DG) formation during agonist-induced cell signaling were investigated in rat pituitary cells and αT3-1 gonadotrophs. In both cell types, GnRH caused a biphasic increase in DG formation, with an initial spike within 60 sec, followed by a larger and sustained rise to reach a second peak after 15 min of stimulation. Both phases of DG production were temporally correlated with inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] formation, consistent with the dependence of DG formation on phospholipase-C-mediated phosphoinositide hydrolysis. However, the ability of GnRH to stimulate phosphatidylethanol (PEt) in the presence of ethanol suggested that phospholipase-D may also participate in DG formation. Two inhibitors of phospholipase-C-dependent phosphoinositide hydrolysis. U73122 and neomycin sulfate, reduced the PEt as well as the Ins(1,4,5)P3 response to GnRH, indicating that phospholipase-D is activated during phospholipase-C-dependent signaling in pituitary gonadotrophs. The production of both DG and PEt was increased by treatment with the active phorbol ester phorbol 12-myristate 13-acetate (PMA), but not with inactive 4α-phorbol 13-didecanoate, indicating that stimulation of protein kinase-C leads to activation of phospholipase-D. In accord with this, GnRH- and PMA-induced elevations of DG and PEt production were attenuated or abolished in protein kinase-C-depleted cells. In contrast, short and long term stimulation with PMA had no effect on basal inositol phosphate production. Also, GnRH-induced inositol phosphate production was not affected by protein kinase-C depletion. Finally, U73122 and neomycin sulfate did not inhibit PMA-induced PEt formation. These data indicate that GnRH activates a dual phospholipase pathway in a sequential and synchronized manner; phospholipase-C initiates the biphasic increase in Ins(1,4,5)P3 and DG formation, and protein kinase-C mediates the integration of phospholipase-D into the signaling response during the sustained phase of agonist stimulation.

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