RESUMO
Early embryogenesis in Xenopus development depends on correct anterior-posterior (A-P) neural patterning during gastrulation. It is known that high levels of retinoic acid (RA), a major intracellular signaling molecule, determine posterior cell fate, also reflecting an involvement in A-P neural patterning. Here we show that the known RA effector, xCOUP-TF, plays important roles in head development of Xenopus embryo. xCOUP-TF-B injection into the dorsal region of embryos induced formation of an abnormal head with small eyes. Analysis of brain marker gene expression revealed that xCOUP-TF-B injection induced slight anteriorization in embryos and attenuated the effects of RA treatment. This anteriorization effect was enhanced when xCOUP-TF-B was co-injected with xCyp26A or xCyp26C, which are known RA metabolizing factors. Furthermore, xCOUP-TF-B injection enhanced xCyp26A/C transcription. Together, these results suggest that xCOUP-TF and xCyp26 are both regulated by Wnt signaling, and cooperatively function in RA signaling to affect A-P neural patterning.
Assuntos
Fator II de Transcrição COUP/genética , Sistema Enzimático do Citocromo P-450/genética , Regulação da Expressão Gênica no Desenvolvimento , Tretinoína/metabolismo , Proteínas de Xenopus/genética , Xenopus laevis/genética , Animais , Padronização Corporal/efeitos dos fármacos , Padronização Corporal/genética , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/embriologia , Embrião não Mamífero/metabolismo , Hibridização In Situ , Isoenzimas/genética , Modelos Genéticos , Sistema Nervoso/efeitos dos fármacos , Sistema Nervoso/embriologia , Sistema Nervoso/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Tretinoína/farmacologia , Xenopus laevis/embriologiaRESUMO
Nuclear dysfunction is a key feature of the pathology of polyglutamine (polyQ) diseases. It has been suggested that mutant polyQ proteins impair functions of nuclear factors by interacting with them directly in the nucleus. However, a systematic analysis of quantitative changes in soluble nuclear proteins in neurons expressing mutant polyQ proteins has not been performed. Here, we perform a proteome analysis of soluble nuclear proteins prepared from neurons expressing huntingtin (Htt) or ataxin-1 (AT1) protein, and show that mutant AT1 and Htt similarly reduce the concentration of soluble high mobility group B1/2 (HMGB1/2) proteins. Immunoprecipitation and pulldown assays indicate that HMGBs interact with mutant AT1 and Htt. Immunohistochemistry showed that these proteins were reduced in the nuclear region outside of inclusion bodies in affected neurons. Compensatory expression of HMGBs ameliorated polyQ-induced pathology in primary neurons and in Drosophila polyQ models. Furthermore, HMGBs repressed genotoxic stress signals induced by mutant Htt or transcriptional repression. Thus, HMGBs may be critical regulators of polyQ disease pathology and could be targets for therapy development.