RESUMO
Small nuclear RING finger protein (SNURF/RNF4) is a steroid receptor coregulator that is down-regulated in testicular germ cell cancer. In this work, we examined SNURF expression during murine fetal gonad development and postnatal ovarian folliculogenesis by in situ hybridization and immunohistochemical staining. SNURF mRNA was detectable in gonads of both sexes from embryonic 10.5 days post conception onward. SNURF protein localized to gonocytes and somatic Leydig and Sertoli cells of fetal testis and in oogonia and supporting cells of fetal ovary. In murine postnatal ovary, SNURF mRNA and protein were expressed throughout folliculogenesis, peaking in the oocytes of preantral follicles. Lower amounts of SNURF mRNA and protein were also present in granulosa cells of secondary, antral, and preovulatory follicles and in luteal glands. Exposure of immature female mice and rats to gonadotropin from pregnant mare serum and human chorionic gonadotropin did not change dramatically SNURF mRNA levels in ovary. SNURF mRNA expression was increased in ovaries of immature mice treated with diethylstilbestrol, an effect that was blocked by the pure antiestrogen ICI 182,780. SNURF protein was constitutively expressed in oocytes of hypophysectomized rats, and its content was augmented by estradiol in granulosa cells. In granulosa cell culture, SNURF mRNA accumulation was transiently increased by treatment with the LH agonists phorbol myristate and forskolin at 4 h after treatment and at 48 h in differentiated cells expressing markers of the preovulatory phenotype. These results suggest a role for SNURF in fetal germ cell development as well as in oocyte and granulosa cell maturation in an estrogen- and gonadotropin-regulated fashion.
Assuntos
Estrogênios/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Gonadotropinas/farmacologia , Proteínas Nucleares/genética , Ovário/crescimento & desenvolvimento , Testículo/crescimento & desenvolvimento , Fatores de Transcrição/genética , Animais , Gonadotropina Coriônica/farmacologia , Colforsina/farmacologia , Feminino , Hormônio Foliculoestimulante/farmacologia , Idade Gestacional , Células da Granulosa/química , Humanos , Hormônio Luteinizante/farmacologia , Masculino , Camundongos , Oócitos/química , Folículo Ovariano/química , Folículo Ovariano/crescimento & desenvolvimento , Ovário/química , Ovário/embriologia , Sondas RNA , RNA Antissenso , RNA Mensageiro/análise , Ratos , Testículo/química , Testículo/embriologia , Acetato de Tetradecanoilforbol/farmacologia , Ubiquitina-Proteína LigasesRESUMO
OBJECTIVE: The role of estrogens and androgens in the etiology and progression of testicular germ cell cancer is poorly understood. To gain insight into the role of sex steroid action in testicular tumorigenesis, we have measured mRNAs encoding estrogen receptor beta (ERbeta), androgen receptor (AR), and their coregulators SNURF/RNF4, PIASx, and PIAS1 in testicular germ cell tumors. METHODS: We used real-time quantitative reverse transcription-PCR assay to compare the steroid receptor and coregulator mRNA levels in 12 matched samples of testicular tumors and adjacent normal tissues (seminomas n=8, nonseminomas n=4). In addition, ERbeta and SNURF/RNF4 protein immunoreactivity was analyzed from paraffin-embedded normal testis and tumor specimens. RESULTS: ERbeta mRNA levels were down-regulated by 59% in seminomas (p=0.017), and those of AR and SNURF/RNF4 mRNAs were decreased by 75% and 67%, respectively, in seminomas and teratocarcinomas compared to paired normal samples (p=0.034 for both, Wilcoxon signed rank test), whereas the PIASx and PIAS1 mRNA were unaltered. ERbeta and SNURF/RNF4 were also clearly down-regulated at the protein level in testicular tumors. CONCLUSIONS: Expression of ERbeta and SNURF/RNF4 was significantly lower in cancerous than in noncancerous testis tissue. Down-regulation of the ERbeta and the coregulator SNURF/RNF4 genes may play a role in testicular tumorigenesis.
Assuntos
Biomarcadores Tumorais/análise , Proteínas de Ligação a DNA/metabolismo , Germinoma/patologia , Receptores de Estrogênio/metabolismo , Neoplasias Testiculares/patologia , Fatores de Transcrição/metabolismo , Adulto , Biópsia por Agulha , Técnicas de Cultura , Proteínas de Ligação a DNA/análise , Regulação para Baixo , Receptor beta de Estrogênio , Germinoma/metabolismo , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Probabilidade , RNA Mensageiro/análise , Receptores Androgênicos/análise , Receptores Androgênicos/metabolismo , Receptores de Estrogênio/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade , Estatísticas não Paramétricas , Neoplasias Testiculares/metabolismo , Fatores de Transcrição/análiseRESUMO
A small nuclear RING finger protein, termed SNURF (or RNF4), is a coregulator of androgen receptor-dependent transcription. To elucidate the physiological role of SNURF in vivo, cell type-specific localization and changes in SNURF mRNA and protein accumulation were followed during testicular development and spermatogenesis of the rat. Two SNURF transcripts, approximately 3.0 and 1.6 kb in size, were detected in adult rat testis. Both mRNA species are capable of encoding full-length SNURF protein. The 3.0 kb SNURF mRNA is persistently expressed in Sertoli cells of both immature and mature testes, whereas the expression of the 1.6 kb transcript appears after day 30 of postnatal life and is restricted to step 4-11 spermatids. Increased accumulation of SNURF in step 4-11 spermatids, which do not express the androgen receptor, indicates that SNURF action is not restricted to the regulation of androgen signaling. Germ cell expression of SNURF coincides with the last transcriptional activity of the haploid genome and alterations in chromatin structure, suggesting that SNURF is involved in the regulation of processes required for late steps of spermatid maturation.
