TY  - JOUR
A1  - Linder, Bastian
A1  - Hirmer, Anja
A1  - Gal, Andreas
A1  - Rüther, Klaus
A1  - Bolz, Hanno Jörn
A1  - Winkler, Christoph
A1  - Laggerbauer, Bernhard
A1  - Fischer, Utz
T1  - Identification of a PRPF4 Loss-of-Function Variant That Abrogates U4/U6.U5 Tri-snRNP Integration and Is Associated with Retinitis Pigmentosa
N2  - Pre-mRNA splicing by the spliceosome is an essential step in the maturation of nearly all human mRNAs. Mutations in six spliceosomal proteins, PRPF3, PRPF4, PRPF6, PRPF8, PRPF31 and SNRNP200, cause retinitis pigmentosa (RP), a disease characterized by progressive photoreceptor degeneration. All splicing factors linked to RP are constituents of the U4/U6.U5 tri-snRNP subunit of the spliceosome, suggesting that the compromised function of this particle may lead to RP. Here, we report the identification of the p.R192H variant of the tri-snRNP factor PRPF4 in a patient with RP. The mutation affects a highly conserved arginine residue that is crucial for PRPF4 function. Introduction of a corresponding mutation into the zebrafish homolog of PRPF4 resulted in a complete loss of function in vivo. A series of biochemical experiments suggested that p.R192H disrupts the binding interface between PRPF4 and its interactor PRPF3. This interferes with the ability of PRPF4 to integrate into the tri-snRNP, as shown in a human cell line and in zebrafish embryos. These data suggest that the p.R192H variant of PRPF4 represents a functional null allele. The resulting haploinsufficiency of PRPF4 compromises the function of the tri-snRNP, reinforcing the notion that this spliceosomal particle is of crucial importance in the physiology of the retina.
KW  - zebrafish
KW  - embryos
KW  - immunoprecipitation
KW  - arginine
KW  - messenger RNA
KW  - spliceosomes
KW  - mutation
KW  - RNA splicing
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-113663
ER  - 
TY  - JOUR
A1  - Gross, Henrik
A1  - Hennard, Christine
A1  - Masouris, Ilias
A1  - Cassel, Christian
A1  - Barth, Stephanie
A1  - Stober-Grässer, Ute
A1  - Mamiani, Alfredo
A1  - Moritz, Bodo
A1  - Ostareck, Dirk
A1  - Ostareck-Lederer, Antje
A1  - Neuenkirchen, Nils
A1  - Fischer, Utz
A1  - Deng, Wen
A1  - Leonhardt, Heinrich
A1  - Noessner, Elfriede
A1  - Kremmer, Elisabeth
A1  - Grässer, Friedrich A.
T1  - Binding of the Heterogeneous Ribonucleoprotein K (hnRNP K) to the Epstein-Barr Virus Nuclear Antigen 2 (EBNA2) Enhances Viral LMP2A Expression
JF  - PLoS One
N2  - The Epstein-Barr Virus (EBV) -encoded EBNA2 protein, which is essential for the in vitro transformation of B-lymphocytes, interferes with cellular processes by binding to proteins via conserved sequence motifs. Its Arginine-Glycine (RG) repeat element contains either symmetrically or asymmetrically di-methylated arginine residues (SDMA and ADMA, respectively). EBNA2 binds via its SDMA-modified RG-repeat to the survival motor neurons protein (SMN) and via the ADMA-RG-repeat to the NP9 protein of the human endogenous retrovirus K (HERV-K (HML-2) Type 1). The hypothesis of this work was that the methylated RG-repeat mimics an epitope shared with cellular proteins that is used for interaction with target structures. With monoclonal antibodies against the modified RG-repeat, we indeed identified cellular homologues that apparently have the same surface structure as methylated EBNA2. With the SDMA-specific antibodies, we precipitated the Sm protein D3 (SmD3) which, like EBNA2, binds via its SDMA-modified RG-repeat to SMN. With the ADMA-specific antibodies, we precipitated the heterogeneous ribonucleoprotein K (hnRNP K). Specific binding of the ADMA-antibody to hnRNP K was demonstrated using E. coli expressed/ADMA-methylated hnRNP K. In addition, we show that EBNA2 and hnRNP K form a complex in EBV-infected B-cells. Finally, hnRNP K, when co-expressed with EBNA2, strongly enhances viral latent membrane protein 2A (LMP2A) expression by an unknown mechanism as we did not detect a direct association of hnRNP K with DNA-bound EBNA2 in gel shift experiments. Our data support the notion that the methylated surface of EBNA2 mimics the surface structure of cellular proteins to interfere with or co-opt their functional properties.
KW  - SM proteins
KW  - protein argentine methyltranserase
KW  - motor-neuron protein
KW  - RNA-polymerase-II
KW  - messenger RNA
KW  - C-MYC
KW  - gene expression
KW  - splicing factor
KW  - down regulation
KW  - living cells
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133707
VL  - 7
IS  - 8
ER  -