Depletion of SMN by RNA interference in HeLa cells induces defects in Cajal body formation
Résumé
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.
Mots clés
Autoantigens/analysis Coiled Bodies/*chemistry Cyclic AMP Response Element-Binding Protein/*antagonists & inhibitors/genetics Cytoplasm/chemistry Hela Cells Humans Nerve Tissue Proteins/*antagonists & inhibitors/genetics Nuclear Proteins/analysis RNA Interference RNA
Guide/analysis RNA
Small Nuclear/analysis RNA-Binding Proteins/*antagonists & inhibitors/genetics Ribonucleoproteins
Small Nuclear/analysis/*metabolism
Domaines
Biochimie, Biologie Moléculaire
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