title: β-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-α (ERα) levels through opposing mechanisms of EMS-mediated trafficking and internalization. While ß-arrestin-mediated mERα 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 ERα 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 mERα. β-arrestin-1 (Arrb1) was found in the ARH and in N-38 neurons. In vitro, E2 increased trafficking and internalization of full-length ERα and ERαΔ4, an alternatively spliced isoform of ERα, 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 ERαΔ4 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 mERα, which are required for the E2-induction of female sexual receptivity.
authors: Department of Neurobiology David Geffen School of Medicine at UCLA and Laboratory of Neuroendocrinology of the Brain Research Institute, at University of California Los Angeles, Los Angeles, California, United States of America.
authors: Angela M
authors: AM
authors: Wong
authors: Department of Neurobiology David Geffen School of Medicine at UCLA and Laboratory of Neuroendocrinology of the Brain Research Institute, at University of California Los Angeles, Los Angeles, California, United States of America.
authors: Matthew C
authors: MC
authors: Abrams
authors: Department of Neurobiology David Geffen School of Medicine at UCLA and Laboratory of Neuroendocrinology of the Brain Research Institute, at University of California Los Angeles, Los Angeles, California, United States of America.
authors: Paul E
authors: PE
authors: Micevych
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000378:metabolism; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004958:Estradiol / Q000031:analogs & derivatives / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D005260:Female; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008297:Male; D009474:Neurons / Q000378:metabolism*; D011187:Posture; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D020318:Rats, Long-Evans; D060888:Real-Time Polymerase Chain Reaction; D012726:Sexual Behavior, Animal; D015398:Signal Transduction; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins
chemical_list: C000605256:Arrb1 protein, rat; D019390:Arrestins; D047628:Estrogen Receptor alpha; D034741:RNA, Small Interfering; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins; C074283:estradiol 3-benzoate; D004958:Estradiol