CAV1 siRNA Reduces Membrane Estrogen Receptor-α Levels and Attenuates Sexual Receptivity

Although classic estrogen receptors (ER) have been proposed to mediate estradiol signaling, it has been relatively recently that mechanisms of trafficking these receptors have been elucidated. ERα is palmitoylated and associates with caveolin proteins to be targeted to the cell membrane. Caveolins are scaffold proteins that not only traffic ERα to the membrane but also are involved in establishing metabotropic glutamate receptor interactions that are necessary for activating G protein signaling. To demonstrate the role of caveolin proteins in regulating an estradiol-dependent behavior, sexual receptivity, we used small interfering RNA to knock down caveolin-1 (CAV1) expression in the arcuate nucleus of the hypothalamus. In CAV1 knockdown rats, membrane, but not intracellular levels of ERα, were significantly reduced. As expected, estrogenic stimulation of the arcuate nucleus of the hypothalamus to medial preoptic nucleus projection was abrogated in CAV1 knockdown rats, indicating that the membrane-initiated activation of this circuit was compromised. Moreover, estradiol-induced lordosis behavior that is dependent on activation of μ-opioid receptors in the medial preoptic nucleus was also significantly reduced. Thus, CAV1-mediated ERα trafficking to the cell membrane is required for estradiol activation of circuits underlying female sexual receptivity.

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Estradiol Dose-Dependent Regulation of Membrane Estrogen Receptor-α, Metabotropic Glutamate Receptor-1a, and Their Complexes in the Arcuate Nucleus of the Hypothalamus in Female Rats

Endocrinology ◽

10.1210/en.2013-1235 ◽

2013 ◽

Vol 154 (9) ◽

pp. 3251-3260 ◽

Cited By ~ 19

Author(s):

Matthew Mahavongtrakul ◽

Martha P. Kanjiya ◽

Maribel Maciel ◽

Shrey Kanjiya ◽

Kevin Sinchak

Keyword(s):

Estrogen Receptor ◽

Glutamate Receptor ◽

Arcuate Nucleus ◽

Metabotropic Glutamate Receptor ◽

Estradiol Benzoate ◽

Estrogen Receptor Α ◽

Female Rats ◽

Female Rat ◽

Metabotropic Glutamate ◽

Dose Dependent

Sexual receptivity in the female rat is dependent on dose and duration of estradiol exposure. A 2 μg dose of estradiol benzoate (EB) primes reproductive behavior circuits without facilitating lordosis. However, 50 μg EB facilitates lordosis after 48 hours. Both EB doses activate membrane estrogen receptor-α (mERα) that complexes with and signals through metabotropic glutamate receptor-1a (mGluR1a). This mERα-mGluR1a signaling activates a multisynaptic lordosis-inhibiting circuit in the arcuate nucleus (ARH) that releases β-endorphin in the medial preoptic nucleus (MPN), activating μ-opioid receptors (MOP). MPN MOP activation is maintained, inhibiting lordosis for 48 hours by 2 μg EB, whereas 50 μg EB at 48 hours deactivates MPN MOP, facilitating lordosis. We hypothesized that 50 μg EB down-regulates ERα and mERα-mGluR1a complexes in the ARH to remove mERα-mGluR1a signaling. In experiment I, 48 hours after 2 μg or 50 μg EB, the number of ARH ERα-immunopositive cells was reduced compared with controls. In experiment II, compared with oil controls, total ARH ERα protein was decreased 48 hours after 50 μg EB, but the 2 μg dose was not. These results indicate that both EB doses reduced the total number of cells expressing ERα, but 2 μg EB may have maintained or increased ERα expressed per cell, whereas 50 μg EB appeared to reduce total ERα per cell. In experiment III, coimmunoprecipitation and Western blot revealed that total mERα and coimmunoprecipitated mERα with mGluR1a were greater 48 hours after 2 μg EB treatment vs rats receiving 50 μg EB. These results indicate 2 μg EB maintains but 50 μg EB down-regulates mERα-mGluR1a to regulate the lordosis circuit activity.

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Alterations in Metabotropic Glutamate Receptor 1α and Regulator of G Protein Signaling 4 in the Prefrontal Cortex in Schizophrenia

American Journal of Psychiatry ◽

10.1176/appi.ajp.2010.10030318 ◽

2010 ◽

Vol 167 (12) ◽

pp. 1489-1498 ◽

Cited By ~ 83

Author(s):

David W. Volk ◽

Stephen M. Eggan ◽

David A. Lewis

Keyword(s):

Prefrontal Cortex ◽

G Protein ◽

Glutamate Receptor ◽

Metabotropic Glutamate Receptor ◽

G Protein Signaling ◽

Protein Signaling ◽

Metabotropic Glutamate

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Transcription Repressor Hes1 Contributes to Neuropathic Pain Development by Modifying CDK9/RNAPII-Dependent Spinal mGluR5 Transcription

International Journal of Molecular Sciences ◽

10.3390/ijms20174177 ◽

2019 ◽

Vol 20 (17) ◽

pp. 4177 ◽

Cited By ~ 3

Author(s):

Ming-Chun Hsieh ◽

Hsien-Yu Peng ◽

Yu-Cheng Ho ◽

Cheng-Yuan Lai ◽

Jen-Kun Cheng ◽

...

Keyword(s):

Neuropathic Pain ◽

Rna Polymerase Ii ◽

Dorsal Horn ◽

Nerve Injury ◽

Metabotropic Glutamate Receptor ◽

Receptor Subtype ◽

Cyclin Dependent Kinase ◽

Metabotropic Glutamate ◽

Interfering Rna ◽

Transcription Expression

Diverse transcriptional controls in the dorsal horn have been observed in pain hypersensitivity. However, the understanding of the exact causes and mechanisms of neuropathic pain development is still fragmentary. Here, the results demonstrated nerve injury decreased the expression of spinal hairy and enhancer of split 1 (Hes1), a transcriptional repressor, and enhanced metabotropic glutamate receptor subtype 5 (mGluR5) transcription/expression, which was accompanied with behavioral allodynia. Moreover, nerve injury decreased Hes1 levels and reciprocally increased cyclin dependent kinase-9 (CDK9) levels and recruited CDK9 to phosphorylate RNA polymerase II (RNAPII) in the promoter fragments of mGluR5, thereby enhancing mGluR5 transcription/expression in the dorsal horn. These effects were also induced by intrathecally administering naïve rats with Hes1 small interfering RNA (siRNA). Conversely, Hes1 overexpression using intrathecal lentiviral vectors in nerve injury rats produced reversal of pain behavior and reversed protein expressions, phosphorylation, and coupling to the promoter segments in the dorsal horn. Collectively, the results in this study indicated nerve injury diminishes spinal Hes1-dependent suppression of CDK9-dependent RNAPII phosphorylation on the mGluR5 promoter that possibly enhances mGluR5 transcription/expression for neuropathic pain development.

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