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Nucleic Acids Res. Aug 25, 1995; 23(16): 3141–3151.
PMCID: PMC307171

Assembly, nuclear import and function of U7 snRNPs studied by microinjection of synthetic U7 RNA into Xenopus oocytes.


In Xenopus oocytes in vitro transcribed mouse U7 RNA is assembled into small nuclear ribonucleoproteins (snRNPs) that are functional in histone RNA 3' processing. If the special Sm binding site of U7 (AAUUUGUCUAG, U7 Sm WT) is converted into the canonical Sm sequence derived from the major snRNAs (AAUUUUUGGAG, U7 Sm OPT) the RNA assembles into a particle which accumulates more efficiently in the nucleus, but which is non-functional. U7 RNA with a heavily mutated Sm binding site (AACGCGUCAUG, U7 Sm MUT) is deficient in nuclear accumulation and function. By UV cross-linking U7 Sm WT RNA can be linked to three proteins, i.e. the common snRNP proteins G and B/B' and an apparently U7-specific protein of 40 kDa. As a result of altering the Sm binding site, U7 Sm OPT RNA cannot be cross-linked to the 40 kDa protein and no cross-links are obtained with U7 Sm MUT RNA. The fact that the Sm site also interacts with at least one U7-specific protein is so far unique to U7 RNA and may provide an explanation for the atypical sequence of this site. All described RNA-protein interactions, including that with the 40 kDa protein, already occur in the cytoplasm. An additional cytoplasmic photoadduct obtained with U7 Sm WT and U7 Sm OPT, but not U7 Sm MUT, RNAs is indicative of a protein of 60-80 kDa. The m7G cap structure of U7 Sm WT and U7 Sm OPT RNA becomes hypermethylated. However, the 3mG cap enhances, but is not required for, nuclear accumulation. Finally, U7 Sm WT RNA is functional in histone RNA processing even when bearing an ApppG cap.

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Selected References

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  • Galli G, Hofstetter H, Stunnenberg HG, Birnstiel ML. Biochemical complementation with RNA in the Xenopus oocyte: a small RNA is required for the generation of 3' histone mRNA termini. Cell. 1983 Oct;34(3):823–828. [PubMed]
  • Gilmartin GM, Schaufele F, Schaffner G, Birnstiel ML. Functional analysis of the sea urchin U7 small nuclear RNA. Mol Cell Biol. 1988 Mar;8(3):1076–1084. [PMC free article] [PubMed]
  • Strub K, Birnstiel ML. Genetic complementation in the Xenopus oocyte: co-expression of sea urchin histone and U7 RNAs restores 3' processing of H3 pre-mRNA in the oocyte. EMBO J. 1986 Jul;5(7):1675–1682. [PMC free article] [PubMed]
  • Smith HO, Tabiti K, Schaffner G, Soldati D, Albrecht U, Birnstiel ML. Two-step affinity purification of U7 small nuclear ribonucleoprotein particles using complementary biotinylated 2'-O-methyl oligoribonucleotides. Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9784–9788. [PMC free article] [PubMed]
  • Lührmann R, Kastner B, Bach M. Structure of spliceosomal snRNPs and their role in pre-mRNA splicing. Biochim Biophys Acta. 1990 Nov 30;1087(3):265–292. [PubMed]
  • Grimm C, Stefanovic B, Schümperli D. The low abundance of U7 snRNA is partly determined by its Sm binding site. EMBO J. 1993 Mar;12(3):1229–1238. [PMC free article] [PubMed]
  • Bond UM, Yario TA, Steitz JA. Multiple processing-defective mutations in a mammalian histone pre-mRNA are suppressed by compensatory changes in U7 RNA both in vivo and in vitro. Genes Dev. 1991 Sep;5(9):1709–1722. [PubMed]
  • Schaufele F, Gilmartin GM, Bannwarth W, Birnstiel ML. Compensatory mutations suggest that base-pairing with a small nuclear RNA is required to form the 3' end of H3 messenger RNA. Nature. 323(6091):777–781. [PubMed]
  • Melin L, Soldati D, Mital R, Streit A, Schümperli D. Biochemical demonstration of complex formation of histone pre-mRNA with U7 small nuclear ribonucleoprotein and hairpin binding factors. EMBO J. 1992 Feb;11(2):691–697. [PMC free article] [PubMed]
  • De Lorenzi M, Rohrer U, Birnstiel ML. Analysis of a sea urchin gene cluster coding for the small nuclear U7 RNA, a rare RNA species implicated in the 3' editing of histone precursor mRNAs. Proc Natl Acad Sci U S A. 1986 May;83(10):3243–3247. [PMC free article] [PubMed]
  • Mowry KL, Steitz JA. Identification of the human U7 snRNP as one of several factors involved in the 3' end maturation of histone premessenger RNA's. Science. 1987 Dec 18;238(4834):1682–1687. [PubMed]
  • Gruber A, Soldati D, Burri M, Schümperli D. Isolation of an active gene and of two pseudogenes for mouse U7 small nuclear RNA. Biochim Biophys Acta. 1991 Jan 17;1088(1):151–154. [PubMed]
  • Phillips SC, Turner PC. Nucleotide sequence of the mouse U7 snRNA gene. Nucleic Acids Res. 1991 Mar 25;19(6):1344–1344. [PMC free article] [PubMed]
  • Phillips SC, Birnstiel ML. Analysis of a gene cluster coding for the Xenopus laevis U7 snRNA. Biochim Biophys Acta. 1992 May 7;1131(1):95–98. [PubMed]
  • Kunkel TA. Rapid and efficient site-specific mutagenesis without phenotypic selection. Proc Natl Acad Sci U S A. 1985 Jan;82(2):488–492. [PMC free article] [PubMed]
  • Kunkel TA, Roberts JD, Zakour RA. Rapid and efficient site-specific mutagenesis without phenotypic selection. Methods Enzymol. 1987;154:367–382. [PubMed]
  • Streit A, Koning TW, Soldati D, Melin L, Schümperli D. Variable effects of the conserved RNA hairpin element upon 3' end processing of histone pre-mRNA in vitro. Nucleic Acids Res. 1993 Apr 11;21(7):1569–1575. [PMC free article] [PubMed]
  • Sanger F, Nicklen S, Coulson AR. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. [PMC free article] [PubMed]
  • England TE, Uhlenbeck OC. 3'-terminal labelling of RNA with T4 RNA ligase. Nature. 1978 Oct 12;275(5680):560–561. [PubMed]
  • Soldati D, Schümperli D. Structural and functional characterization of mouse U7 small nuclear RNA active in 3' processing of histone pre-mRNA. Mol Cell Biol. 1988 Apr;8(4):1518–1524. [PMC free article] [PubMed]
  • Lund E, Dahlberg JE. In vitro synthesis of vertebrate U1 snRNA. EMBO J. 1989 Jan;8(1):287–292. [PMC free article] [PubMed]
  • Dignam JD, Lebovitz RM, Roeder RG. Accurate transcription initiation by RNA polymerase II in a soluble extract from isolated mammalian nuclei. Nucleic Acids Res. 1983 Mar 11;11(5):1475–1489. [PMC free article] [PubMed]
  • Mital R, Albrecht U, Schümperli D. Detection of UV-induced RNA:protein crosslinks in snRNPs by oligonucleotides complementary to the snRNA. Nucleic Acids Res. 1993 Feb 25;21(4):1049–1050. [PMC free article] [PubMed]
  • Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. [PubMed]
  • Lerner EA, Lerner MR, Janeway CA, Jr, Steitz JA. Monoclonal antibodies to nucleic acid-containing cellular constituents: probes for molecular biology and autoimmune disease. Proc Natl Acad Sci U S A. 1981 May;78(5):2737–2741. [PMC free article] [PubMed]
  • Luhrmann R, Appel B, Bringmann P, Rinke J, Reuter R, Rothe S, Bald R. Isolation and characterization of rabbit anti-m3 2,2,7G antibodies. Nucleic Acids Res. 1982 Nov 25;10(22):7103–7113. [PMC free article] [PubMed]
  • Heinrichs V, Hackl W, Lührmann R. Direct binding of small nuclear ribonucleoprotein G to the Sm site of small nuclear RNA. Ultraviolet light cross-linking of protein G to the AAU stretch within the Sm site (AAUUUGUGG) of U1 small nuclear ribonucleoprotein reconstituted in vitro. J Mol Biol. 1992 Sep 5;227(1):15–28. [PubMed]
  • Reuter R, Lührmann R. Immunization of mice with purified U1 small nuclear ribonucleoprotein (RNP) induces a pattern of antibody specificities characteristic of the anti-Sm and anti-RNP autoimmune response of patients with lupus erythematosus, as measured by monoclonal antibodies. Proc Natl Acad Sci U S A. 1986 Nov;83(22):8689–8693. [PMC free article] [PubMed]
  • Mattaj IW. Cap trimethylation of U snRNA is cytoplasmic and dependent on U snRNP protein binding. Cell. 1986 Sep 12;46(6):905–911. [PubMed]
  • Pan ZQ, Prives C. Assembly of functional U1 and U2 human-amphibian hybrid snRNPs in Xenopus laevis oocytes. Science. 1988 Sep 9;241(4871):1328–1331. [PubMed]
  • Cazenave C, Chevrier M, Nguyen TT, Hélène C. Rate of degradation of [alpha]- and [beta]-oligodeoxynucleotides in Xenopus oocytes. Implications for anti-messenger strategies. Nucleic Acids Res. 1987 Dec 23;15(24):10507–10521. [PMC free article] [PubMed]
  • Hamm J, Dathan NA, Mattaj IW. Functional analysis of mutant Xenopus U2 snRNAs. Cell. 1989 Oct 6;59(1):159–169. [PubMed]
  • Peculis BA, Steitz JA. Sequence and structural elements critical for U8 snRNP function in Xenopus oocytes are evolutionarily conserved. Genes Dev. 1994 Sep 15;8(18):2241–2255. [PubMed]
  • Stefanovic B, Wittop Koning TH, Schümperli D. A synthetic histone pre-mRNA-U7 small nuclear RNA chimera undergoing cis cleavage in the cytoplasm of Xenopus oocytes. Nucleic Acids Res. 1995 Aug 25;23(16):3152–3160. [PMC free article] [PubMed]
  • Jarmolowski A, Mattaj IW. The determinants for Sm protein binding to Xenopus U1 and U5 snRNAs are complex and non-identical. EMBO J. 1993 Jan;12(1):223–232. [PMC free article] [PubMed]
  • Lutz-Freyermuth C, Keene JD, Lutz-Reyermuth C. The U1 RNA-binding site of the U1 small nuclear ribonucleoprotein (snRNP)-associated A protein suggests a similarity with U2 snRNPs. Mol Cell Biol. 1989 Jul;9(7):2975–2982. [PMC free article] [PubMed]
  • Patton JR, Habets W, van Venrooij WJ, Pederson T. U1 small nuclear ribonucleoprotein particle-specific proteins interact with the first and second stem-loops of U1 RNA, with the A protein binding directly to the RNA independently of the 70K and Sm proteins. Mol Cell Biol. 1989 Aug;9(8):3360–3368. [PMC free article] [PubMed]
  • Query CC, Bentley RC, Keene JD. A specific 31-nucleotide domain of U1 RNA directly interacts with the 70K small nuclear ribonucleoprotein component. Mol Cell Biol. 1989 Nov;9(11):4872–4881. [PMC free article] [PubMed]
  • Surowy CS, van Santen VL, Scheib-Wixted SM, Spritz RA. Direct, sequence-specific binding of the human U1-70K ribonucleoprotein antigen protein to loop I of U1 small nuclear RNA. Mol Cell Biol. 1989 Oct;9(10):4179–4186. [PMC free article] [PubMed]
  • Fisher DE, Conner GE, Reeves WH, Wisniewolski R, Blobel G. Small nuclear ribonucleoprotein particle assembly in vivo: demonstration of a 6S RNA-free core precursor and posttranslational modification. Cell. 1985 Oct;42(3):751–758. [PubMed]
  • Nigg EA, Baeuerle PA, Lührmann R. Nuclear import-export: in search of signals and mechanisms. Cell. 1991 Jul 12;66(1):15–22. [PubMed]
  • Fischer U, Darzynkiewicz E, Tahara SM, Dathan NA, Lührmann R, Mattaj IW. Diversity in the signals required for nuclear accumulation of U snRNPs and variety in the pathways of nuclear transport. J Cell Biol. 1991 May;113(4):705–714. [PMC free article] [PubMed]
  • Fischer U, Lührmann R. An essential signaling role for the m3G cap in the transport of U1 snRNP to the nucleus. Science. 1990 Aug 17;249(4970):786–790. [PubMed]
  • Hamm J, Darzynkiewicz E, Tahara SM, Mattaj IW. The trimethylguanosine cap structure of U1 snRNA is a component of a bipartite nuclear targeting signal. Cell. 1990 Aug 10;62(3):569–577. [PubMed]
  • Michaud N, Goldfarb D. Microinjected U snRNAs are imported to oocyte nuclei via the nuclear pore complex by three distinguishable targeting pathways. J Cell Biol. 1992 Feb;116(4):851–861. [PMC free article] [PubMed]
  • Fischer U, Heinrich J, van Zee K, Fanning E, Lührmann R. Nuclear transport of U1 snRNP in somatic cells: differences in signal requirement compared with Xenopus laevis oocytes. J Cell Biol. 1994 Jun;125(5):971–980. [PMC free article] [PubMed]
  • Marshallsay C, Lührmann R. In vitro nuclear import of snRNPs: cytosolic factors mediate m3G-cap dependence of U1 and U2 snRNP transport. EMBO J. 1994 Jan 1;13(1):222–231. [PMC free article] [PubMed]
  • Feeney RJ, Zieve GW. Nuclear exchange of the U1 and U2 snRNP-specific proteins. J Cell Biol. 1990 Apr;110(4):871–881. [PMC free article] [PubMed]

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