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A novel protein with RNA-binding motifs interacts with ataxin-2
H Shibata1, D P Huynh, S M Pulst
1Division of Neurology and Rose Moss Laboratory for Parkinson and Neurodegenerative Diseases, Burns and Allen Research Institute, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA 90048, USA.
Abstract:
Spinocerebellar ataxia type 2 (SCA2) is caused by expansion of a polyglutamine tract in ataxin-2, a protein of unknown function. Using the yeast two-hybrid system, we identified a novel protein, A2BP1 (ataxin-2 binding protein 1) which binds to the C-terminus of ataxin-2. Northern blot analysis showed that A2BP1 was predominantly expressed in muscle and brain. By immunocfluorescent staining, A2BP1 and ataxin-2 were both localized to the trans -Golgi network. Immunocytochemistry showed that A2BP1 was expressed in the cytoplasm of Purkinje cells and dentate neurons in a pattern similar to that seen for ataxin-2 labeling. Western blot analysis of subcellular fractions indicated enrichment of A2BP1 in the same fractions as ataxin-2. Sequence analysis of the A2BP1 cDNA revealed an RNP motif that is highly conserved among RNA-binding proteins. A2BP1 had striking homology with a human cDNA clone, P83A20, of unknown function and at least two copies of A2BP1 homologs are found in the Caenorhabditis elegans genome database. A2BP1 and related proteins appear to form a novel gene family sharing RNA-binding motifs.
Insights
Researchers discovered ataxin-2 binding protein 1 (A2BP1), a novel protein interacting with ataxin-2, a key player in spinocerebellar ataxia type 2 (SCA2). This finding sheds light on SCA2 pathogenesis and potential therapeutic targets.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder linked to polyglutamine tract expansion in ataxin-2.
- The function of ataxin-2, a protein implicated in SCA2, remains largely unknown.
- Understanding ataxin-2 interactions is crucial for elucidating SCA2 mechanisms.
Purpose of the Study:
- To identify novel proteins that interact with ataxin-2.
- To characterize the function and localization of newly identified ataxin-2 binding partners.
- To explore the potential role of these interactions in SCA2 pathogenesis.
Main Methods:
- Yeast two-hybrid system for identifying protein interactions.
- Northern blot and Western blot analyses for gene and protein expression.
- Immunocytochemistry and immunofluorescence for protein localization.
- Sequence analysis of cDNA for motif identification.
Main Results:
- A novel protein, ataxin-2 binding protein 1 (A2BP1), was identified as binding to the C-terminus of ataxin-2.
- A2BP1 exhibits predominant expression in muscle and brain tissues.
- Both A2BP1 and ataxin-2 localize to the trans-Golgi network and share similar expression patterns in Purkinje cells and dentate neurons.
- Sequence analysis revealed an RNA-binding motif (RNP motif) in A2BP1, suggesting a role in RNA metabolism.
- A2BP1 shows homology to other proteins, indicating the existence of a novel gene family.
Conclusions:
- A2BP1 is a novel binding partner of ataxin-2, potentially involved in SCA2.
- The shared subcellular localization and expression patterns suggest a functional relationship between A2BP1 and ataxin-2.
- A2BP1, with its RNA-binding motif, may play a role in RNA processing or transport relevant to neuronal function and SCA2.
- The identification of A2BP1 and its homologs opens new avenues for research into ataxin-2 function and SCA2.