Disease relevance of U2AF1

• As U2AF1 associates with a number of different factors during mRNA splicing, overexpression in trisomy 21 individuals could contribute to some Down syndrome phenotypes by interfering with the splicing process [1].
• Indeed, quantitative real-time PCR demonstrated a reduced level of expression of one of these factors, U2AF35, in pancreatic cancer cells compared with healthy pancreas [2].
• Here we show that U2AF35 appears to be completely dispensable for splicing in nuclear extracts prepared from adenovirus late-infected cells (Ad-NE) [3].
• These results demonstrated that PAH and IUGR could be mediated by feto-placental hRN through its permeability to the maternal circulation, not by feto-placental hANG production [4].
• Selected phage clones displayed a peptide RVPPRYHAKISPMVN (called RN-peptide) on their surface [5].

High impact information on U2AF1

• A novel peptide recognition mode revealed by the X-ray structure of a core U2AF35/U2AF65 heterodimer [6].
• Our results demonstrate a new biochemical activity of U2AF35, identify the factor that initially recognizes the 3' splice site, and explain why the AG dinucleotide is required for the first step of splicing for some but not all introns [7].
• Here we use site-specific crosslinking to show that very early during spliceosome assembly U2AF35 directly contacts the 3' splice site [7].
• U2AF65 binds to RNA at the polypyrimidine tract, whereas U2AF35 is thought to interact through its arginine/serine-rich (RS) domain with other RS-domain-containing factors bound at the 5' splice site, assembled in splicing enhancer complexes, or associated with the U4/U6.U5 small nuclear ribonucleoprotein complex [8].
• The splicing factor U2AF (U2 snRNP auxiliary factor) is a heterodimer with subunits of 65 and 35 kD (U2AF65 and U2AF35) [9].

Biological context of U2AF1

• Using the U2AF1 cDNA as a probe, we mapped this gene to cosmid Q15D2, a P1, and YAC 350F7 of the Chumakov et al [1].
• Furthermore, the relative amount of missplicing of the CCK-B receptor mini-gene in the pancreatic cancer cell line was reversed by transfection of the cells with U2AF35 cDNA [2].
• Using yeast two-hybrid screens and in vitro binding studies, we found that this region coincides with a direct binding site for U2AF35, the small subunit of the splicing factor U2AF [10].
• We have analyzed the interaction between the U2AF subunits U2AF35 and U2AF65 in vivo using fluorescence resonance energy transfer (FRET) microscopy [11].
• Mutations in the A-rich region of the CRS both eliminate cyclic nucleotide regulation of mRNA decay and abolish RN-protein complex formation, suggesting that these RNA-binding proteins may be important regulators of mRNA stability [12].

Anatomical context of U2AF1

• Both U2AF65 and U2AF35 are concentrated in a small number of nuclear foci corresponding to coiled bodies, subnuclear organelles first identified by light microscopy in 1903 [13].
• Using two different approaches for measuring FRET, we have identified and spatially localized sites of direct interaction between U2AF35 and U2AF65 in vivo in live cell nuclei [11].

Associations of U2AF1 with chemical compounds

• The X-ray structure of the human core U2AF heterodimer, consisting of the U2AF35 central domain and a proline-rich region of U2AF65, has been determined at 2.2 A resolution [6].
• The structure reveals a novel protein-protein recognition strategy, in which an atypical RNA recognition motif (RRM) of U2AF35 and the U2AF65 polyproline segment interact via reciprocal "tongue-in-groove" tryptophan residues [6].
• In this model, recruitment requires interactions between the SR proteins and the 35-kDa subunit of U2AF (U2AF35) [14].
• U2 snRNP Auxiliary Factor (U2AF) is an essential pre-mRNA splicing factor complex, comprising 35-kDa (U2AF35) and 65-kDa (U2AF65) subunits [11].
• The 65- and 35-kD subunits of the splicing factor U2AF, U2AF65 and U2AF35, recognize, respectively, the pyrimidine-rich tract and the conserved terminal AG present at metazoan 3' splice sites [15].

Physical interactions of U2AF1

• FRET analyses of the U2AF complex localize the U2AF35/U2AF65 interaction in vivo and reveal a novel self-interaction of U2AF35 [11].

Other interactions of U2AF1

• A misspliced form of the cholecystokinin-B/gastrin receptor in pancreatic carcinoma: role of reduced sellular U2AF35 and a suboptimal 3'-splicing site leading to retention of the fourth intron [2].
• We further found in human cells that the exogenously expressed large U2AF subunit, U2AF65, accumulates in spliced mRNP, leading to the recruitment of U2AF35 and TAP [10].
• The molecular cloning of a 4.1 cDNA encoding the isoform designated 4.1E has allowed us to show that this protein is targeted to the nucleus, that it associates with the splicing factor U2AF35, and that its overexpression induces the redistribution of the splicing factor SC35 [16].
• 3. One trapped sequence showed complete homology with the cDNA of human U2AF35 (M96982; HGM-approved nomenclature U2AF1), which encodes for the small 35-kDa subunit of the U2 snRNP auxiliary factor [1].
• DEK phosphorylated at serines 19 and 32 associates with U2AF35, facilitates the U2AF35-AG interaction and prevents binding of U2AF65 to pyrimidine tracts not followed by AG [15].

Analytical, diagnostic and therapeutic context of U2AF1

• In order to evaluate the resolution of this RH panel, we have now constructed a radiation hybrid map of the Chromosome (Chr) 15q2.3-q2.6 region containing the RN gene [17].

References