RESUMO
Fanconi anemia (FA) is associated with variable developmental abnormalities, bone marrow failure and cancer susceptibility. FANCG/XRCC9 is member of the FA core complex, a group of proteins that control the monoubiquitylation of FANCD2, an event that plays a critical role in maintaining genomic stability. Here we report the identification of the Xenopus laevis ortholog of human FANCG (xFANCG), its expression during development, and its molecular interactions with a partner protein, xFANCA. The xFANCG protein sequence is 47% similar to its human ortholog, with highest conservation in the two putative N-terminal leucine zippers and the tetratricopeptide repeat (TPR) motifs. xFANCG is maternally and zygotically transcribed. Prior to the midblastula stage, a single xFANCG transcript is observed but two additional alternatively spliced mRNAs are detected after the midblastula transition. One of the variants is predicted to encode a novel isoform of xFANCG lacking exon 2. The mutual association between FANCG and FANCA required for their nuclear import is conserved in Xenopus egg extracts. Our data demonstrate that interactions between FANCA and FANCG occur at the earliest stage of vertebrate development and raise the possibility that functionally different isoforms of xFANCG may play a role in early development.
Assuntos
Proteína do Grupo de Complementação G da Anemia de Fanconi/genética , Regulação da Expressão Gênica no Desenvolvimento , Xenopus laevis/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Sequência Conservada , DNA Complementar/isolamento & purificação , Embrião não Mamífero , Éxons , Proteína do Grupo de Complementação A da Anemia de Fanconi/metabolismo , Proteína do Grupo de Complementação G da Anemia de Fanconi/isolamento & purificação , Proteína do Grupo de Complementação G da Anemia de Fanconi/metabolismo , Humanos , Dados de Sequência Molecular , Ligação Proteica , Isoformas de Proteínas/genética , Isoformas de Proteínas/isolamento & purificação , RNA Mensageiro Estocado/isolamento & purificação , RNA Mensageiro Estocado/metabolismo , Homologia de Sequência , Xenopus laevis/embriologiaRESUMO
We have isolated an cDNA after applying a DDRT-PCR analysis on mRNA from mature resting cysts of the ciliate Oxytricha (Sterkiella) nova. From this cDNA fragment the complete macronuclear minichromosome was obtained by using the Mac-End-PCR method. After cloning and sequencing, this cDNA shown certain similarity to HMG-like proteins. The analysis of the inferred amino acid sequence shown that this putative HMG-like protein has one HMG-box interrupted by a intron. The analysis of others characteristics (including a 3D model) confirms that it is a HMGB family protein. It is the first time that a macronuclear gene encoding a putative HMG-box protein is isolated from resting cysts of a stichotrich ciliate. The possible implications of this stored mRNA in the ciliate cryptobiotic stage are discussed.