p68 RNA helicase is an essential human splicing factor that acts at the U1 snRNA-5' splice site duplex.
Modulation of the interaction between U1 snRNP and the 5' splice site (5'ss) is a key event that governs 5'ss recognition and spliceosome assembly. Using the methylene blue-mediated cross-linking method (Z. R. Liu, A. M. Wilkie, M. J. Clemens, and C. W. Smith, RNA 2:611-621, 1996), a 65-kDa protein (p65) was shown to interact with the U1-5'ss duplex during spliceosome assembly (Z. R. Liu, B. Sargueil, and C. W. Smith, Mol. Cell. Biol. 18:6910-6920, 1998). In this report, p65 was identified as p68 RNA helicase and shown to be essential for in vitro pre-mRNA splicing. Depletion of endogenous p68 RNA helicase does not affect the loading of the U1 snRNP to the 5'ss during early stage of splicing. However, dissociation of the U1 from the 5'ss is largely inhibited. The data suggest that p68 RNA helicase functions in destabilizing the U1-5'ss interactions. Furthermore, depletion of p68 RNA helicase arrested spliceosome assembly at the prespliceosome stage, suggesting that p68 may play a role in the transition from prespliceosome to spliceosome.
Liu
Zhi-Ren
ZR
Program in Cell & Molecular Biosciences, Department of Animal Sciences, Auburn University, 210 Upchurch Hall, Auburn, AL 36849, USA. zrliu@acesag.auburn.edu
D020121:5' Untranslated Regions / Q000737:chemistry / Q000378:metabolism*; D015153:Blotting, Western; D002457:Cell Extracts / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight; D023282:Nuclease Protection Assays; D011233:Precipitin Tests; D011485:Protein Binding / Q000502:physiology; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D020365:RNA Helicases / Q000737:chemistry / Q000378:metabolism*; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism; D012326:RNA Splicing / Q000502:physiology*; D012342:RNA, Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D017381:Spliceosomes / Q000737:chemistry* / Q000378:metabolism
D020121:5' Untranslated Regions; D002457:Cell Extracts; D046911:Macromolecular Substances; D012322:RNA Precursors; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA; D011494:Protein Kinases; C506749:Ddx5 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases