The Opitz syndrome gene product MID1 assembles a microtubule-associated ribonucleoprotein complex

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• 作者：Beatriz Aranda-Orgillés ; Alexander Trockenbacher ; Jennifer Winter ; Johanna Aigner ; Andrea K?hler ; Ewa Jastrzebska ; Joachim Stahl ; Eva-Christina Müller ; Albrecht Otto and Erich E. Wanker ; et al.
• 刊名：Human Genetics
• 出版年：2008
• 出版时间：March, 2008
• 年：2008
• 卷：123
• 期：2
• 页码：163-176
• 全文大小：635.2 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Biomedicine
  Human Genetics
  Molecular Medicine
  Internal Medicine
  Metabolic Diseases
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1432-1203

文摘

Opitz BBB/G syndrome (OS) is a heterogenous malformation syndrome mainly characterised by hypertelorism and hypospadias. In addition, patients may present with several other defects of the ventral midline such as cleft lip and palate and congenital heart defects. The syndrome-causing gene encodes the X-linked E3 ubiquitin ligase MID1 that mediates ubiquitin-specific modification and degradation of the catalytic subunit of the translation regulator protein phosphatase 2A (PP2A). Here, we show that the MID1 protein also associates with elongation factor 1α (EF-1α) and several other proteins involved in mRNA transport and translation, including RACK1, Annexin A2, Nucleophosmin and proteins of the small ribosomal subunits. Mutant MID1 proteins as found in OS patients lose the ability to interact with EF-1α. The composition of the MID1 protein complex was determined by several independent methods: (1) yeast two-hybrid screening and (2) immunofluorescence, (3) a biochemical approach involving affinity purification of the complex, (4) co-fractionation in a microtubule assembly assay and (5) immunoprecipitation. Moreover, we show that the cytoskeleton-bound MID1/translation factor complex specifically associates with G- and U-rich RNAs and incorporates MID1 mRNA, thus forming a microtubule-associated ribonucleoprotein (RNP) complex. Our data suggest a novel function of the OS gene product in directing translational control to the cytoskeleton. The dysfunction of this mechanism would lead to malfunction of microtubule-associated protein translation and to the development of OS.