title: Rpp20 interacts with SMN and is re-distributed into SMN granules in response to stress.
abstract: Spinal muscular atrophy (SMA) is a neurodegenerative disorder resulting from homozygous loss of the SMN1 gene. To investigate SMN functions, we undertook the yeast two-hybrid screens and identified Drosophila Rpp20, a subunit of the RNase P and RNase MRP holoenzymes, to interact with the Drosophila SMN protein. Interaction between human SMN and Rpp20 was validated by in vitro binding assays and co-immunoprecipitation. The exons 3-4 of SMN are necessary and sufficient for binding to Rpp20. Binding efficiency between Rpp20 and SMNs with mutations in the Y-G domain is abrogated or reduced and correlated with severity of SMA disease. Immunofluorescence results indicate that Rpp20 is diffusely distributed throughout the cytoplasm with higher concentration observed in the nucleus. However, in response to stress, SMN forms aggregates and redistributes Rpp20 into punctuated cytoplasmic SMN granules. Our findings suggest a possible functional association of SMN with RNase P and RNase MRP complexes.
authors.affiliation: Department of Medicine, Program in Neuroscience, University of Massachusetts, Medical School, Worcester, MA 01605, USA.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Hua
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein; D004330:Drosophila; D006367:HeLa Cells; D018869:Heat-Shock Response / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D009134:Muscular Atrophy, Spinal / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D011485:Protein Binding; D016601:RNA-Binding Proteins; D043262:Ribonuclease P; D055532:SMN Complex Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D055533:Survival of Motor Neuron 1 Protein; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques
chemical_list: D001324:Autoantigens; D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; C112706:POP7 protein, human; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein; D043262:Ribonuclease P