scholarly journals Estradiol Modulates Translocator Protein (TSPO) and Steroid Acute Regulatory Protein (StAR) via Protein Kinase A (PKA) Signaling in Hypothalamic Astrocytes

Endocrinology ◽  
2014 ◽  
Vol 155 (8) ◽  
pp. 2976-2985 ◽  
Author(s):  
Claire Chen ◽  
John Kuo ◽  
Angela Wong ◽  
Paul Micevych
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Primary Cultures ◽  
Regulatory Protein ◽  
Estrogen Receptor Α ◽  
Translocator Protein ◽  
Calcium Stores ◽  
Female Rat ◽  
Transporter Protein ◽  
Kinase A

The ability of the central nervous system to synthesize steroid hormones has wide-ranging implications for physiology and pathology. Among the proposed roles of neurosteroids is the regulation of the LH surge. This involvement in the estrogen-positive feedback demonstrates the integration of peripheral steroids with neurosteroids. Within the female hypothalamus, estradiol from developing follicles stimulates progesterone synthesis in astrocytes, which activate neural circuits regulating gonadotropin (GnRH) neurons. Estradiol acts at membrane estrogen receptor-α to activate cellular signaling that results in the release of inositol trisphosphate-sensitive calcium stores that are sufficient to induce neuroprogesterone synthesis. The purpose of the present studies was to characterize the estradiol-induced signaling leading to activation of steroid acute regulatory protein (StAR) and transporter protein (TSPO), which mediate the rate-limiting step in steroidogenesis, ie, the transport of cholesterol into the mitochondrion. Treatment of primary cultures of adult female rat hypothalamic astrocytes with estradiol induced a cascade of phosphorylation that resulted in the activation of a calcium-dependent adenylyl cyclase, AC1, elevation of cAMP, and activation of both StAR and TSPO. Blocking protein kinase A activation with H-89 abrogated the estradiol-induced neuroprogesterone synthesis. Thus, together with previous results, these experiments completed the characterization of how estradiol action at the membrane leads to the augmentation of neuroprogesterone synthesis through increasing cAMP, activation of protein kinase A, and the phosphorylation of TSPO and StAR in hypothalamic astrocytes.

scholarly journals Spatial targeting of type II protein kinase A to filopodia mediates the regulation of growth cone guidance by cAMP

2007 ◽  
Vol 176 (1) ◽  
pp. 101-111 ◽  
Author(s):  
Jianzhong Han ◽  
Liang Han ◽  
Priyanka Tiwari ◽  
Zhexing Wen ◽  
James Q. Zheng
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Growth Cone ◽  
Regulatory Protein ◽  
Cyclic Adenosine Monophosphate ◽  
Spatial Localization ◽  
Adenosine Monophosphate ◽  
Type Ii ◽  
Regulation Of Growth ◽  
Kinase A

The second messenger cyclic adenosine monophosphate (cAMP) plays a pivotal role in axonal growth and guidance, but its downstream mechanisms remain elusive. In this study, we report that type II protein kinase A (PKA) is highly enriched in growth cone filopodia, and this spatial localization enables the coupling of cAMP signaling to its specific effectors to regulate guidance responses. Disrupting the localization of PKA to filopodia impairs cAMP-mediated growth cone attraction and prevents the switching of repulsive responses to attraction by elevated cAMP. Our data further show that PKA targets protein phosphatase-1 (PP1) through the phosphorylation of a regulatory protein inhibitor-1 (I-1) to promote growth cone attraction. Finally, we find that I-1 and PP1 mediate growth cone repulsion induced by myelin-associated glycoprotein. These findings demonstrate that the spatial localization of type II PKA to growth cone filopodia plays an important role in the regulation of growth cone motility and guidance by cAMP.

scholarly journals Convergence of 3′,5′-Cyclic Adenosine 5′-Monophosphate/Protein Kinase A and Glycogen Synthase Kinase-3β/β-Catenin Signaling in Corpus Luteum Progesterone Synthesis

Endocrinology ◽  
2009 ◽  
Vol 150 (11) ◽  
pp. 5036-5045 ◽  
Author(s):  
Lynn Roy ◽  
Claudia A. McDonald ◽  
Chao Jiang ◽  
Dulce Maroni ◽  
Anthony J. Zeleznik ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Corpus Luteum ◽  
Glycogen Synthase ◽  
Regulatory Protein ◽  
Glycogen Synthase Kinase ◽  
Proximal Promoter ◽  
Progesterone Secretion ◽  
Progesterone Synthesis ◽  
Kinase A

Progesterone secretion by the steroidogenic cells of the corpus luteum (CL) is essential for reproduction. Progesterone synthesis is under the control of LH, but the exact mechanism of this regulation is unknown. It is established that LH stimulates the LH receptor/choriogonadotropin receptor, a G-protein coupled receptor, to increase cAMP and activate cAMP-dependent protein kinase A (PKA). In the present study, we tested the hypothesis that cAMP/PKA-dependent regulation of the Wnt pathway components glycogen synthase kinase (GSK)-3β and β-catenin contributes to LH-dependent steroidogenesis in luteal cells. We observed that LH via a cAMP/PKA-dependent mechanism stimulated the phosphorylation of GSK3β at N-terminal Ser9 causing its inactivation and resulted in the accumulation of β-catenin. Overexpression of N-terminal truncated β-catenin (Δ90 β-catenin), which lacks the phosphorylation sites responsible for its destruction, significantly augmented LH-stimulated progesterone secretion. In contrast, overexpression of a constitutively active mutant of GSK3β (GSK-S9A) reduced β-catenin levels and inhibited LH-stimulated steroidogenesis. Chromatin immunoprecipitation assays demonstrated the association of β-catenin with the proximal promoter of the StAR gene, a gene that expresses the steroidogenic acute regulatory protein, which is a cholesterol transport protein that controls a rate-limiting step in steroidogenesis. Collectively these data suggest that cAMP/PKA regulation of GSK3β/β-catenin signaling may contribute to the acute increase in progesterone production in response to LH.

scholarly journals The Role of Protein Kinase A in the Ethanol-Induced Increase in Spontaneous GABA Release Onto Cerebellar Purkinje Neurons

2008 ◽  
Vol 100 (6) ◽  
pp. 3417-3428 ◽  
Author(s):  
M. Katherine Kelm ◽  
Hugh E. Criswell ◽  
George R. Breese
Keyword(s):  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Protein Kinase A ◽  
Calcium Release ◽  
Cannabinoid Receptor ◽  
Gaba Release ◽  
Calcium Stores ◽  
Postsynaptic Neuron ◽  
Current Frequency ◽  
Kinase A

Ethanol increases miniature inhibitory postsynaptic current frequency and decreases the paired-pulse ratio, which suggests that ethanol increases both spontaneous and evoked GABA release, respectively. We have shown previously that ethanol increases GABA release at the rat interneuron–Purkinje cell synapse and that this ethanol effect involves calcium release from internal stores; however, further exploration of the mechanism responsible for ethanol-enhanced GABA release was needed. We found that a cannabinoid receptor 1 (CB1) agonist, WIN-55212, and a GABAB receptor agonist, baclofen, decreased baseline spontaneous GABA release and prevented ethanol from increasing spontaneous GABA release. The CB1 receptor and GABAB receptor are Gα i–linked G protein–coupled receptors with common downstream messengers that include adenylate cyclase and protein kinase A (PKA). Adenylate cyclase and PKA antagonists blocked ethanol from increasing spontaneous GABA release, whereas a PKA antagonist limited to the postsynaptic neuron did not block ethanol from increasing spontaneous GABA release. These results suggest that presynaptic PKA plays an essential role in ethanol-enhanced spontaneous GABA release. Similar to ethanol, we found that the mechanism of the cannabinoid-mediated decrease in spontaneous GABA release involves internal calcium stores and PKA. A PKA antagonist decreased baseline spontaneous GABA release. This effect was reduced after incubating the slice with a calcium chelator, BAPTA-AM, but was unaffected when BAPTA was limited to the postsynaptic neuron. This suggests that the PKA antagonist is acting through a presynaptic, calcium-dependent mechanism to decrease spontaneous GABA release. Overall, these results suggest that PKA activation is necessary for ethanol to increase spontaneous GABA release.

scholarly journals The Lutropin/Choriogonadotropin Receptor-Induced Phosphorylation of the Extracellular Signal-Regulated Kinases in Leydig Cells Is Mediated by a Protein Kinase A-Dependent Activation of Ras

2003 ◽  
Vol 17 (11) ◽  
pp. 2189-2200 ◽  
Author(s):  
Takashi Hirakawa ◽  
Mario Ascoli
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Leydig Cells ◽  
Primary Cultures ◽  
Nucleotide Exchange ◽  
Camp Phosphodiesterase ◽  
Human Choriogonadotropin ◽  
Extracellular Signal ◽  
Guanosine Triphosphatase ◽  
Kinase A

Abstract The pathways involved in activation of the ERK1/2 cascade in Leydig cells were examined in MA-10 cells expressing the recombinant human LH receptor (hLHR) and in primary cultures of rat Leydig cell precursors. In MA-10 cells expressing the recombinant hLHR, human choriogonadotropin-induced activation of ERK1/2 is effectively inhibited by overexpression of a cAMP phosphodiesterase (a manipulation that blunts the human choriogonadotropin-induced cAMP response), by addition of H89 (a selective inhibitor of protein kinase A), or by overexpression of the heat-stable protein kinase A inhibitor, but not by overexpression of an inactive mutant of this inhibitor. Stimulation of hLHR did not activate Rap1, but activated Ras in an H89-sensitive fashion. Addition of H89 to MA-10 cells that had been cotransfected with a guanosine triphosphatase-deficient mutant of Ras almost completely inhibited the hLHR-mediated activation of ERK1/2. We also show that 8-bromo-cAMP activates Ras and ERK1/2 in MA-10 cells and in primary cultures of rat Leydig cells precursors in an H89-sensitive fashion, whereas a cAMP analog 8-(4-chloro-phenylthio)-2′-O-methyl-cAMP (8CPT-2Me-cAMP) that is selective for cAMP-dependent guanine nucleotide exchange factor has no effect. Collectively, our results show that the hLHR-induced phosphorylation of ERK1/2 in Leydig cells is mediated by a protein kinase A-dependent activation of Ras.

scholarly journals Phosphorylation of Human Estrogen Receptor α by Protein Kinase A Regulates Dimerization

1999 ◽  
Vol 19 (2) ◽  
pp. 1002-1015 ◽  
Author(s):  
Dongsheng Chen ◽  
Paul E. Pace ◽  
R. Charles Coombes ◽  
Simak Ali
Keyword(s):  
Estrogen Receptor ◽  
Protein Kinase ◽  
Dna Binding ◽  
Ligand Binding ◽  
Protein Kinase A ◽  
Estrogen Receptor Α ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Ici 182,780 ◽  
Kinase A

ABSTRACT Phosphorylation provides an important mechanism by which transcription factor activity is regulated. Estrogen receptor α (ERα) is phosphorylated on multiple sites, and stimulation of a number of growth factor receptors and/or protein kinases leads to ligand-independent and/or synergistic increase in transcriptional activation by ERα in the presence of estrogen. Here we show that ERα is phosphorylated by protein kinase A (PKA) on serine-236 within the DNA binding domain. Mutation of serine-236 to glutamic acid prevents DNA binding by inhibiting dimerization by ERα, whereas mutation to alanine has little effect on DNA binding or dimerization. Furthermore, PKA overexpression or activation of endogenous PKA inhibits dimerization in the absence of ligand. This inhibition is overcome by the addition of 17β-estradiol or the partial agonist 4-hydroxy tamoxifen. Interestingly, treatment with the complete antagonist ICI 182,780 does not overcome the inhibitory effect of PKA activation. Our results indicate that in the absence of ligand ERα forms dimers through interaction between DNA binding domains and that dimerization mediated by the ligand binding domain only occurs upon ligand binding but that the complete antagonist ICI 182,780 prevents dimerization through the ligand-binding domain. Heterodimer formation between ERα and ERβ is similarly affected by PKA phosphorylation of serine 236 of ERα. However, 4-hydroxytamoxifen is unable to overcome inhibition of dimerization by PKA. Thus, phosphorylation of ERα in the DNA binding domain provides a mechanism by which dimerization and thereby DNA binding by the estrogen receptor is regulated.

Renal cortical basolateral Na+/HCO 3 ? cotransporter III. Evidence for a regulatory protein in the inhibitory effect of protein kinase A

1995 ◽  
Vol 145 (1) ◽  
Author(s):  
A.A. Bernardo ◽  
F.T. Kear ◽  
J.A. Stim ◽  
Y.Y. Qiu ◽  
O.S. Ruiz ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Regulatory Protein ◽  
Inhibitory Effect ◽  
Kinase A
Sign in / Sign up

Export Citation Format

Share Document