HMGA proteins are chromatin “architectural modifiers”, bearing three conserved “AT-hook” motifs with which they bind to DNA AT-rich regions to assist in gene transcription. We report the developmental expression of Xenopus laevis hmga2β (Xhmga2β) and of hmgax (Xhmgax), a gene encoding a highly divergent HMGA with eight AT-hooks. Xhmga2β transcripts are first detected before the midblastula transition (MBT) by RT-PCR and then become more abundant. By in situ hybridisation (ISH), localized transcripts are first detected at neurula stages, in the presumptive central nervous system (CNS) and eye field. At tailbud and tadpole stages, Xlhmga2β mRNA is detected in the CNS, in the otic vesicles, in neural crest cell derivatives, in the notochord and in the medio-lateral mesoderm. Xlhmgax expression is detected, by RT-PCR, from stage 2 to tailbud stage and then decreases at tadpole stage. Xlhmgax mRNA is detected by ISH at the tailbud and tadpole stages. Localized mRNAs are present in various head regions, and in particular in the hindbrain, optic and otic vesicles, and in the branchial arches. We also investigated the biochemical properties of XHMGA2β. In GST-pull down assays, we found that, similar to murine HMGA1, it is able to interact with OTX/CRX homeodomain transcription factors. Furthermore, EMSA showed that the DNA-binding properties of XHMGA2β, but not of XHMGAx, are shared with the human homologue. In order to address the functional roles of both Xhmga2β and Xhmgax, gain and loss of function experiments are underway.

HMGA proteins in Xenopus laevis

VIGNALI, ROBERT;ONORATI, MARCO;
2008

Abstract

HMGA proteins are chromatin “architectural modifiers”, bearing three conserved “AT-hook” motifs with which they bind to DNA AT-rich regions to assist in gene transcription. We report the developmental expression of Xenopus laevis hmga2β (Xhmga2β) and of hmgax (Xhmgax), a gene encoding a highly divergent HMGA with eight AT-hooks. Xhmga2β transcripts are first detected before the midblastula transition (MBT) by RT-PCR and then become more abundant. By in situ hybridisation (ISH), localized transcripts are first detected at neurula stages, in the presumptive central nervous system (CNS) and eye field. At tailbud and tadpole stages, Xlhmga2β mRNA is detected in the CNS, in the otic vesicles, in neural crest cell derivatives, in the notochord and in the medio-lateral mesoderm. Xlhmgax expression is detected, by RT-PCR, from stage 2 to tailbud stage and then decreases at tadpole stage. Xlhmgax mRNA is detected by ISH at the tailbud and tadpole stages. Localized mRNAs are present in various head regions, and in particular in the hindbrain, optic and otic vesicles, and in the branchial arches. We also investigated the biochemical properties of XHMGA2β. In GST-pull down assays, we found that, similar to murine HMGA1, it is able to interact with OTX/CRX homeodomain transcription factors. Furthermore, EMSA showed that the DNA-binding properties of XHMGA2β, but not of XHMGAx, are shared with the human homologue. In order to address the functional roles of both Xhmga2β and Xhmgax, gain and loss of function experiments are underway.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/237947
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