title: Depletion of SMN by RNA interference in HeLa cells induces defects in Cajal body formation.
abstract: Neuronal degeneration in spinal muscular atrophy (SMA) is caused by reduced expression of the survival of motor neuron (SMN) protein. The SMN protein is ubiquitously expressed and is present both in the cytoplasm and in the nucleus where it localizes in Cajal bodies. The SMN complex plays an essential role for the biogenesis of spliceosomal U-snRNPs. In this article, we have used an RNA interference approach in order to analyse the effects of SMN depletion on snRNP assembly in HeLa cells. Although snRNP profiles are not perturbed in SMN-depleted cells, we found that SMN depletion gives rise to cytoplasmic accumulation of a GFP-SmB reporter protein. We also demonstrate that the SMN protein depletion induces defects in Cajal body formation with coilin being localized in multiple nuclear foci and in nucleolus instead of canonical Cajal bodies. Interestingly, the coilin containing foci do not contain snRNPs but appear to co-localize with U85 scaRNA. Because Cajal bodies represent the location in which snRNPs undergo 2'-O-methylation and pseudouridylation, our results raise the possibility that SMN depletion might give rise to a defect in the snRNA modification process.
authors.affiliation: Institut de Génétique Moléculaire, CNRS, UMR5535 IFR 122, 1919 route de Mende, 34000 Montpellier, France.
authors.forename: Cyrille
authors.initials: C
authors.lastname: Girard
authors.forename: Henry
authors.initials: H
authors.lastname: Neel
authors.forename: Edouard
authors.initials: E
authors.lastname: Bertrand
authors.forename: Rémy
authors.initials: R
authors.lastname: Bordonné
mesh_terms: D001324:Autoantigens / Q000032:analysis; D020541:Coiled Bodies / Q000737:chemistry*; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors* / Q000235:genetics; D003593:Cytoplasm / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D009687:Nuclear Proteins / Q000032:analysis; D034622:RNA Interference; D012342:RNA, Small Nuclear / Q000032:analysis; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D017411:Ribonucleoproteins, Small Nuclear / Q000032:analysis / Q000378:metabolism*; D055532:SMN Complex Proteins; D055517:snRNP Core Proteins; D058727:RNA, Small Untranslated
chemical_list: D001324:Autoantigens; D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055532:SMN Complex Proteins; C526407:SNRPB protein, human; C526417:SNRPN protein, human; D055517:snRNP Core Proteins; C068921:p80-coilin; D058727:RNA, Small Untranslated