Disease relevance of PRPF8

• PURPOSE: Mutations in the systemically expressed pre-mRNA splicing-factor genes PRPF3, PRPF8, and PRPF31 have recently been associated with autosomal dominant retinitis pigmentosa (adRP) [1].
• Blots of recombinant E. coli fusion proteins encoded by exons 3-7 of the p220 and p180 isoforms were uniformly non-reactive with SLE IgM, suggesting that anti-CD45 autoantibodies in SLE are directed against conformational and/or carbohydrate epitopes, rather than linear polypeptide epitopes [2].

High impact information on PRPF8

• The early 5' splice site/tri-snRNP interaction requires ATP, occurs in both nematode and HeLa cell extracts, and involves sequence-specific interactions between the highly conserved splicing factor Prp8 and the 5' splice site [3].
• Map refinement of locus RP13 to human chromosome 17p13.3 in a second family with autosomal dominant retinitis pigmentosa [4].
• The anonymous DNA marker locus D17S938, linked to adRP locus RP13 on chromosome 17p13.1, yielded a suggestive but not statistically significant positive lod score [4].
• The kinetics and biochemical requirements of the UV-crosslinking of p220 corresponded to the kinetics and biochemical requirements of spliceosome formation [5].
• The recent identification of mutations in human splicing factors, PRPF31 and PRPC8, led us to screen HPRP3 as a candidate in three chromosome 1q-linked families [6].

Biological context of PRPF8

• This study was intended to identify mutations in PRPF3, PRPF8, and PRPF31 in 150 Spanish families affected by adRP, to measure the contribution of mutations in these genes to adRP in that population, and to correlate RP phenotype expression with mutations in pre-mRNA splicing-factor genes [1].
• RESULTS: Three nonsense mutations caused by insertion and deletion sequences and two missense mutations (Arg2310Gly) and within the stop codon of the PRPF8 gene (TGA-->TTG), were detected in five unrelated heterozygous patients [1].
• In this study we used the fragment between helix C and D of PAI-2 as a bait to perform a yeast two-hybrid screen using a cDNA library constructed with HeLa cells during apoptosis, and retrieved a clone encoding 94 amino acid residues of C-terminus of pre-mRNA processing factor 8 (PRPF8) [7].
• To report the clinical and functional characteristics of an autosomal dominant retinitis pigmentosa (ADRP) family with a novel point mutation (P2301S) in the PRPF8 gene [8].
• These five polioviruses efficiently cleaved p220 but showed defects in viral protein synthesis, transactivation of a leader-luciferase mRNA, and 3CD cleavage to 3C' and 3D'. All 2Apro mutant sequences, including those that did not yield viable viruses, were cloned in pTM1 vector under a T7 promoter [9].

Anatomical context of PRPF8

• These results suggest structural conservation of the splicing factor PRP8 from yeast to mammals and show that this protein is in close proximity to the pre-mRNA in the spliceosome [5].
• Addition of MBP-2A(pro) to rabbit reticulocyte cell-free systems gives rise to efficient cleavage of the initiation factor of translation p220 (eIF-4G) [10].
• Immunoblot analysis with antisera to the p220 subunit of eIF-4F demonstrated extensive but incomplete cleavage of p220 in infected K562 cells at times which correlated with peak viral protein synthesis [11].
• We now show that the avian bursal B cells and B-cell lines, RP-9, RP-13 and DT40, express chicken BAFF (cBAFF) [12].

Associations of PRPF8 with chemical compounds

• Unlike alteration of p220, alteration of the 25 C C1 antigen is not due to a protease which can be detected by cell lysate mixing experiments [13].
• Cleavage of p220 (gamma subunit of eukaryotic initiation factor 4 [eIF-4 gamma]), a component of the translation initiation factor eIF-4F, occurs to the same extent in poliovirus-infected cells whether or not they are treated with monensin [14].

Physical interactions of PRPF8

• PAI-2 could bind PRPF8 C-terminal in both the inside and outside of nuclear [7].

Other interactions of PRPF8

• Cosegregation of the mutation in PRPF8 and PRPF3 with adRP was observed [1].
• These mutations prevent the interaction of Snu114 with Prp8 as well as with U5 snRNA [15].
• Seven different mutations were identified, two of which are novel (458delC and 6901C-->T (P2301S), in the CRX and PRPF8 genes, respectively) [16].
• Interestingly, the highly conserved loop I appears to be a multifunctional element; in addition to its function in splice-site selection the 5' loop is involved in binding of p220 and in the assembly of the U4/U5/U6 triple snRNP [17].
• Time spent in ICU was shorter (median RP 24 vs. TP 46 hours, p = 0.0104), but duration of hospitalisation was longer for the RP-group (median RP 13 vs. TP 10.5 days, p = 0.0156) [18].

Analytical, diagnostic and therapeutic context of PRPF8

• Co-immunoprecipitation experiments confirmed that PAI-2 could interact with PRPF8 in vivo [7].
• On Western blots, antibodies against the yeast splicing factor PRP8 recognized a doublet of proteins, the faster migrating of which comigrated with p220 [5].

References