RESUMO
Eukaryotic genomes contain either one or two genes encoding homologs of the highly conserved histone chaperone Asf1, however, little is known of their in vivo roles in animal development. UNC-85 is one of the two Caenorhabditis elegans Asf1 homologs and functions in post-embryonic replication in neuroblasts. Although UNC-85 is broadly expressed in replicating cells, the specificity of the mutant phenotype suggested possible redundancy with the second C. elegans Asf1 homolog, ASFL-1. The asfl-1 mRNA is expressed in the meiotic region of the germline, and mutants in either Asf1 genes have reduced brood sizes and low penetrance defects in gametogenesis. The asfl-1, unc-85 double mutants are sterile, displaying defects in oogenesis and spermatogenesis, and analysis of DNA synthesis revealed that DNA replication in the germline is blocked. Analysis of somatic phenotypes previously observed in unc-85 mutants revealed that they are neither observed in asfl-1 mutants, nor enhanced in the double mutants, with the exception of enhanced male tail abnormalities in the double mutants. These results suggest that the two Asf1 homologs have partially overlapping functions in the germline, while UNC-85 is primarily responsible for several Asf1 functions in somatic cells, and is more generally involved in replication throughout development.
Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/genética , Genes de Helmintos , Proteínas de Helminto/metabolismo , Histonas/metabolismo , Chaperonas Moleculares/metabolismo , Animais , Caenorhabditis elegans/embriologia , Caenorhabditis elegans/fisiologia , Proteínas de Caenorhabditis elegans/genética , Replicação do DNA , Transtornos do Desenvolvimento Sexual/genética , Embrião não Mamífero , Feminino , Proteínas de Helminto/genética , Histonas/genética , Hibridização In Situ , Masculino , Meiose , Modelos Biológicos , Chaperonas Moleculares/genética , Oogênese/genética , RNA Mensageiro/metabolismo , Espermatogênese/genéticaRESUMO
The ovarian hormones, estradiol (E) and progesterone (P) facilitate the expression of sexual behavior in female rats. E and P mediate many of these behavioral effects by binding to their respective intracellular receptors in specific brain regions. Nuclear receptor coactivators, including Steroid Receptor Coactivator-1 (SRC-1) and CREB Binding Protein (CBP), dramatically enhance ligand-dependent steroid receptor transcriptional activity in vitro. Previously, our lab has shown that SRC-1 and CBP modulate estrogen receptor (ER)-mediated induction of progestin receptor (PR) gene expression in the ventromedial nucleus of the hypothalamus (VMN) and hormone-dependent sexual receptivity in female rats. Female sexual behaviors can be activated by high doses of E alone in ovariectomized rats, and thus are believed to be ER-dependent. However, the full repertoire of female sexual behavior, in particular, proceptive behaviors such as hopping, darting and ear wiggling, are considered to be PR-dependent. In the present experiments, the function of SRC-1 and CBP in distinct ER- (Exp. 1) and PR- (Exp. 2) dependent aspects of female sexual behavior was investigated. In Exp. 1, infusion of antisense oligodeoxynucleotides to SRC-1 and CBP mRNA into the VMN decreased lordosis intensity in rats treated with E alone, suggesting that these coactivators modulate ER-mediated female sexual behavior. In Exp. 2, antisense to SRC-1 and CBP mRNA around the time of P administration reduced PR-dependent ear wiggling and hopping and darting. Taken together, these data suggest that SRC-1 and CBP modulate ER and PR action in brain and influence distinct aspects of hormone-dependent sexual behaviors. These findings support our previous studies and provide further evidence that SRC-1 and CBP function together to regulate ovarian hormone action in behaviorally-relevant brain regions.