| 2007 |
Human IWS1 (hIws1) was identified as an Spt6-interacting protein that associates with the mRNA nuclear export factor REF1/Aly; depletion of hIws1 caused mRNA processing defects, reduced REF1/Aly occupancy at the c-myc gene, and nuclear retention of bulk poly(A)+ RNAs, establishing IWS1 as a cotranscriptional recruiter of mRNA export machinery downstream of Spt6 binding to Ser2-phosphorylated RNAPII CTD. |
Co-immunoprecipitation, siRNA knockdown, chromatin immunoprecipitation (ChIP), nuclear poly(A)+ RNA retention assay in HeLa cells |
Genes & development |
High |
17234882
|
| 2008 |
IWS1 bridges two CTD-binding proteins, Spt6 and HYPB/Setd2, in a megacomplex on the RNAPII elongation machinery; knockdown of IWS1 abolished H3K36me3 across the transcribed regions of c-Myc, HIV-1, and PABPC1 genes and also increased H3K27me3 at the 5' end of PABPC1 and histone acetylation across coding regions, demonstrating that IWS1 recruits Setd2 to direct co-transcriptional H3K36 trimethylation. |
siRNA knockdown, ChIP for H3K36me3/H3K27me3/acetylation, Co-IP, in vitro Spt6-CTD binding assay with recombinant proteins |
Genes & development |
High |
19141475
|
| 2021 |
AKT-mediated phosphorylation of IWS1 promotes H3K36me3 deposition in target gene bodies, which controls LEDGF/SRSF1-dependent inclusion of exon 2 in U2AF2 pre-mRNA; the resulting exon-2-containing U2AF65 is required for proper CDCA5 pre-mRNA processing, Sororin expression, ERK phosphorylation, and G2/M progression. Loss of IWS1 phosphorylation produces an RS-domain-deficient U2AF65 that cannot support these downstream events, impairing cell proliferation. |
RNA-seq after IWS1 phosphorylation block, RT-PCR, ChIP for H3K36me3, functional rescue experiments, xenograft tumor growth assays, analysis of EGFR-mutant lung adenocarcinoma specimens |
Nature communications |
High |
34330897
|
| 2021 |
The RS-domain-containing U2AF65 isoform (produced under phospho-IWS1-dependent splicing) recruits Prp19 to CAR-element-containing intronless mRNAs and promotes their nuclear export; U2AF65 loading to CAR-elements was RS-domain-independent but RNA Pol II-dependent. IWS1-phosphorylation-deficient cells express reduced IFNα1/IFNβ1 protein and show enhanced sensitivity to cytolytic virus infection. |
RNA immunoprecipitation, Co-IP, siRNA knockdown, viral infection assays, caspase activation assays |
Communications biology |
Medium |
34635782
|
| 2019 |
In mouse preimplantation embryos, IWS1 interacts with nuclear AKT, and inhibition of the PI3K/AKT pathway reduced global H3K36me3 whereas activation increased it, suggesting AKT modulates H3K36me3 through interaction with IWS1; knockdown of Iws1 or Supt6 individually blocked development at the 8/16-cell stage with defects in pre-mRNA splicing, mRNA export, and Nanog expression. |
siRNA microinjection in mouse embryos, Co-IP (IWS1 with nuclear AKT), immunofluorescence for H3K36me3, PI3K/AKT pathway inhibitor/activator treatment |
Scientific reports |
Medium |
30846735
|
| 2025 |
Cryo-EM structure of the activated Pol II elongation complex shows IWS1 acts as a scaffold that positions downstream DNA within the cleft of Pol II. The intrinsically disordered C-terminal region of IWS1 contacts the Pol II cleft and, together with ELOF1, stimulates Pol II elongation velocity. Rapid depletion of IWS1 in human cells caused a global decrease in RNA synthesis and Pol II elongation velocity; the associated decrease in H3K36me3 was found to be an indirect, secondary consequence of reduced transcription rather than a direct IWS1 function. |
Cryo-EM structure determination, multi-omics kinetic analysis after auxin-inducible IWS1 degron, in vitro transcription assays, mutagenesis of IWS1 C-terminal disordered region |
Nature communications |
High |
40835814
|
| 2025 |
Cryo-EM mapping revealed that the intrinsically disordered C-terminal region of IWS1 contains short linear motifs (SLiMs) that contact Pol II subunits RPB1, RPB2, and RPB5, elongation factors DSIF, SPT6, and ELOF1; IWS1 recruitment to the elongation complex requires the RPB1 jaw interaction and downstream DNA binding, while transcription stimulation requires RPB2 lobe and ELOF1 contacts. IWS1 was found to protect the elongation complex from RECQL5 inhibition. Additionally, the histone reader LEDGF (an IWS1 interactor) was shown to bind a transcribed downstream nucleosome. |
Cryo-EM structure determination, in vitro transcription assays with IWS1 SLiM mutants, functional recruitment assays, RECQL5 competition assays |
Nucleic acids research |
High |
42134803
|
| 2025 |
Molecular docking using the AlphaFold-predicted IWS1 structure identified a core Spt6-binding region (AA 545–694) of IWS1; candidate small-molecule inhibitors Ketotifen and Desloratadine were predicted to mimic Spt6 Phe217 and disrupt the IWS1/Spt6 complex, which was confirmed by co-immunoprecipitation. Disruption of this interaction increased nuclear localization of IWS1 and reduced migration, invasion, and spheroid formation in dedifferentiated liposarcoma cells. |
Molecular docking/virtual screening, Co-immunoprecipitation, cell migration/invasion assays, spheroid formation assay, immunofluorescence for subcellular localization |
Scientific reports |
Low |
40594510
|
| 2022 |
Genetic suppressor screen in S. cerevisiae showed that viability in the absence of Spn1/Iws1 can be achieved by mutations in FACT, Set2, Rpd3S, Rtt109, Chd1, or Sgf73, placing Spn1/Iws1 function at the intersection of histone acetylation and multiple histone chaperone pathways; this epistasis indicates Spn1 acts to overcome repressive chromatin through multiple mechanisms during transcription elongation. |
Suppressor genetics (bypass suppressor screen), yeast viability assays, genetic epistasis |
Genetics |
Medium |
35977387
|
| 2025 |
IWS1's intrinsically disordered C-terminal region (SLiMs) is responsible for stimulation of Pol II elongation activity, as demonstrated by in vitro assays; this region acts together with ELOF1 to enhance Pol II processivity. |
In vitro transcription elongation assay, cryo-EM, SLiM mutagenesis |
bioRxivpreprint |
Medium |
40909601
|