Disease relevance of SFPQ

• We demonstrate that the cytogenetically defined translocation t(X;1)(p11.2;p34) observed in papillary renal cell carcinomas results in the fusion of the splicing factor gene PSF located at 1p34 to the TFE3 helix-loop-helix transcription factor gene at Xp11 [1].
• Compared to those with reduced systolic function, patients with HF-PSF are more often female, older, less likely to have coronary artery disease, and more likely to have hypertension [2].

High impact information on SFPQ

• This complex contains the inosine-specific RNA binding protein p54(nrb), the splicing factor PSF, and the inner nuclear matrix structural protein matrin 3 [3].
• Biochemical complementation, antibody inhibition, and immunodepletion experiments demonstrate that PSF is an essential pre-mRNA splicing factor required early in spliceosome formation [4].
• The PSF-NonO complex is involved in the regulation of many cellular processes, such as transcription, RNA processing, DNA unwinding and repair [5].
• Purified PSF is known to UV crosslink to pyrimidine tracts, and our data show that PSF UV crosslinks to pre-mRNA in purified C complex [6].
• Thus, PSF may replace the 3' splice site binding factor U2AF65 which is destabilized during spliceosome assembly [6].

Biological context of SFPQ

• NonO (p54nrb), the human homologue of the Drosophila gene NonAdiss which controls the male courtship song, is closely related to PSF and also believed to be involved in RNA splicing [1].
• DJ-1-specific small interfering RNA sensitizes cells to PSF-induced apoptosis [7].
• Interestingly, activator- and CTD-dependent stimulation of splicing mediated by PSF appears to primarily affect the removal of first introns [8].
• A physiological role of this stimulatory mechanism seems feasible, because topoisomerase I and PSF showed a patched colocalization in A431 cell nuclei, which varied with cell cycle [9].
• Functional analysis of these mutants by transfection experiments in a cell line overexpressing the IGF-I receptor (NWTb3) found that an inability to bind PSF significantly increased the IGFRE transcriptional activity, while retaining responsiveness to IGF-I [10].

Anatomical context of SFPQ

• In addition, the expression of PSF-TFE3 in normal renal proximal tubular epithelial cells from where such tumors originate leads to dedifferentiation and loss of some key functional proteins, which may reflect an initial step in the multistep process of tumor development [11].
• Moreover, transfection of expression vectors for Sp1 and PSF in porcine granulosa cells found that Sp1 expression stimulated IGFRE transcriptional activity while PSF inhibited activity even with coexpression of Sp1 [10].
• Two proteins present in HeLa cell extract, the splicing and transcription-associated factors, PSF and p54nrb/NonO, bound specifically and could be purified to virtual homogeneity by chromatography on immobilized CTD matrices [12].
• Platelet electrophoretic mobility slowing factor (PSF) in supernatants of human lymphocytes stimulated with phytohaemagglutinin (PHA) [13].

Associations of SFPQ with chemical compounds

• Accordingly, we propose that PSF acts as a PR corepressor and contributes to the functional withdrawal of progesterone and the initiation of human labor [14].
• CONCLUSION:: This study found that in these subjects a total daily dose of 1200mg ibuprofen did not produce any clinically or statistically significant alterations in the character and quality of nightime sleep as measured using standard sleep laboratory PSF and subjective measures [15].
• Increase of PSF with the oxalate load was significantly greater during a calcium-restricted diet than during the 1.5-gram calcium diet in all groups of patients (4, 6 and 12 times greater in NC, DH and IH, respectively) [16].
• All patients had a high risk index (PSF) for phosphatic stones and 12 also for calcium oxalate stones [17].
• Further benefits could be obtained by using community health workers, now integrated into the Family Medicine Program (PSF) health teams, to provide health education, supervise home care, refer mothers to health centers and facilitate their access to hospitals [18].
• PSF does not affect AR protein stability, as in the case of the progesterone receptor, but impedes the interaction of AR with the androgen response element [19].

Physical interactions of SFPQ

• Here we show that PSF interacts with p54nrb, a highly related protein first identified based on cross-reactivity to antibodies against the yeast second-step splicing factor Prpl8 [20].

Regulatory relationships of SFPQ

• Unlike pathogenic DJ-1 mutants, wild-type DJ-1 acts to inhibit the transcriptional silencing activity of the PSF [7].
• PSF/p54(nrb) stimulates "jumping" of DNA topoisomerase I between separate DNA helices [21].

Other interactions of SFPQ

• Deletion of RRM2 led to a complete loss of speckle localization and resulted in diffuse accumulation of PSF in the nucleus, indicating that RRM2 is required for subnuclear localization [22].
• Further, the repression of hCYP17 promoter-reporter construct luciferase activity resulted from PSF interacting with the corepressor mSin3A [23].
• Here, we demonstrate a direct interaction between topoisomerase I and pyrimidine tract binding protein-associated splicing factor (PSF), a cofactor of RNA splicing, which forms heterodimers with its smaller homolog, the nuclear RNA-binding protein of 54 kDa (p54) [9].
• In this study, we showed that polypyrimidine tract-binding protein (PTB)-associated splicing factor (PSF), an RNA-binding component of spliceosomes, binds to the IGFRE [10].
• Splicing and transcription-associated proteins PSF and p54nrb/nonO bind to the RNA polymerase II CTD [12].

Analytical, diagnostic and therapeutic context of SFPQ

• Affinity chromatography experiments reveal that two factors previously implicated in the coupling of transcription and pre-mRNA processing, PSF and p54(nrb)/NonO, preferentially bind a strong rather than a weak activation domain [8].
• P splicing factor (PSF) was identified as one of the proteins and this interaction was confirmed by Western blotting [24].
• PSF/p54(nrb) enhanced the cleavage rate of the second oligonucleotide (11-fold), suggesting that it stimulates the dissociation of topoisomerase I after ligation [21].
• The interaction between the splicing factors PSF and PTB/hnRNP I was confirmed by co-immunoprecipitation from nuclear salt extracts [25].
• Cohort studies of hospitalized patients show a smaller proportion of HF-PSF [2].

References