?-arrestin regulates estradiol membrane-initiated signaling in hypothalamic neurons.

ABSTRACT: Estradiol (E2) action in the nervous system is the result of both direct nuclear and membrane-initiated signaling (EMS). E2 regulates membrane estrogen receptor-? (ER?) levels through opposing mechanisms of EMS-mediated trafficking and internalization. While ß-arrestin-mediated mER? internalization has been described in the cortex, a role of ß-arrestin in EMS, which underlies multiple physiological processes, remains undefined. In the arcuate nucleus of the hypothalamus (ARH), membrane-initiated E2 signaling modulates lordosis behavior, a measure of female sexually receptivity. To better understand EMS and regulation of ER? membrane levels, we examined the role of ß-arrestin, a molecule associated with internalization following agonist stimulation. In the present study, we used an immortalized neuronal cell line derived from embryonic hypothalamic neurons, the N-38 line, to examine whether ß-arrestins mediate internalization of mER?. ?-arrestin-1 (Arrb1) was found in the ARH and in N-38 neurons. In vitro, E2 increased trafficking and internalization of full-length ER? and ER??4, an alternatively spliced isoform of ER?, which predominates in the membrane. Treatment with E2 also increased phosphorylation of extracellular-signal regulated kinases 1/2 (ERK1/2) in N-38 neurons. Arrb1 siRNA knockdown prevented E2-induced ER??4 internalization and ERK1/2 phosphorylation. In vivo, microinfusions of Arrb1 antisense oligodeoxynucleotides (ODN) into female rat ARH knocked down Arrb1 and prevented estradiol benzoate-induced lordosis behavior compared with nonsense scrambled ODN (lordosis quotient: 3 ± 2.1 vs. 85.0 ± 6.0; p < 0.0001). These results indicate a role for Arrb1 in both EMS and internalization of mER?, which are required for the E2-induction of female sexual receptivity.

SUBMITTER: Wong AM 

PROVIDER: S-EPMC4372564 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature