title: Assembly and trafficking of box C/D and H/ACA snoRNPs.
abstract: Box C/D and box H/ACA snoRNAs are abundant non-coding RNAs that localize in the nucleolus and mostly function as guides for nucleotide modifications. While a large pool of snoRNAs modifies rRNAs, an increasing number of snoRNAs could also potentially target mRNAs. ScaRNAs belong to a family of specific RNAs that localize in Cajal bodies and that are structurally similar to snoRNAs. Most scaRNAs are involved in snRNA modification, while telomerase RNA, which contains H/ACA motifs, functions in telomeric DNA synthesis. In this review, we describe how box C/D and H/ACA snoRNAs are processed and assembled with core proteins to form functional RNP particles. Their biogenesis involve several transport factors that first direct pre-snoRNPs to Cajal bodies, where some processing steps are believed to take place, and then to nucleoli. Assembly of core proteins involves the HSP90/R2TP chaperone-cochaperone system for both box C/D and H/ACA RNAs, but also several factors specific for each family. These assembly factors chaperone unassembled core proteins, regulate the formation and disassembly of pre-snoRNP intermediates, and control the activity of immature particles. The AAA+ ATPase RUVBL1 and RUVBL2 belong to the R2TP co-chaperones and play essential roles in snoRNP biogenesis, as well as in the formation of other macro-molecular complexes. Despite intensive research, their mechanisms of action are still incompletely understood.
authors.affiliation: a Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS , 9 Avenue de la forêt de Haye, 54505 Vandoeuvre-les-Nancy Cedex , France , Université de Lorraine, Campus Biologie -Santé , CS 50184, 54505 Vandoeuvre-les-Nancy Cedex , France.
authors.forename: Séverine
authors.identifier: 0000-0001-5187-8356
authors.initials: S
authors.lastname: Massenet
authors.affiliation: b Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS , 1919 route de Mende, 34293 Montpellier cedex 5 , France , Université de Montpellier , 163 rue Auguste Broussonnet, 34090 Montpellier , France.
authors.forename: Edouard
authors.initials: E
authors.lastname: Bertrand
authors.affiliation: b Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS , 1919 route de Mende, 34293 Montpellier cedex 5 , France , Université de Montpellier , 163 rue Auguste Broussonnet, 34090 Montpellier , France.
authors.forename: Céline
authors.initials: C
authors.lastname: Verheggen
mesh_terms: D000818:Animals; D002352:Carrier Proteins; D020541:Coiled Bodies / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D046912:Multiprotein Complexes / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D012323:RNA Processing, Post-Transcriptional; D020537:RNA, Small Nucleolar / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020718:Ribonucleoproteins, Small Nucleolar / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D002352:Carrier Proteins; D018841:HSP90 Heat-Shock Proteins; D046912:Multiprotein Complexes; D020537:RNA, Small Nucleolar; D020718:Ribonucleoproteins, Small Nucleolar
keywords: Hsp90/R2TP; RNP assembly; RNP trafficking; box C/D RNP; box H/ACA RNP; scaRNA; snoRNA