Iws1, an RNA-polymerase II (RNAPII)-associated transcription elongation factor, is conserved from yeast (where it is known as Spn1) to humans. It is essential for various biological processes. Iws1 interacts with the histone H3/H4 chaperone Spt6, recruits the lysine methyltransferase Setd2 to chromatin, and is involved in regulating H3K36me3, which is crucial for pre-mRNA splicing and mRNA export. Genetic models, like KO mouse models, are valuable for studying its functions [2,4,5,6].

In Toxoplasma gondii, IWS1-deficient parasites show decreased ROP18 mRNA expression, increased loading of IFN-inducible GTPases onto the parasitophorous vacuole membrane, and reduced virulence in wild-type mice but normal virulence in IFN-γ receptor-lacking mice. This indicates that T. gondii IWS1 indirectly regulates ROP18 mRNA expression to determine fitness in IFN-γ-activated host cells and mice [1].

In mice, knockdown of either Iws1 or Supt6 (Spt6 in mouse gene ontology) blocks embryo development, primarily at the 8/16-cell stage, and affects pre-mRNA splicing, mRNA export, and the expression of lineage-specific transcription factors. Iws1 is also required for H3K36 trimethylation during mouse early development [2].

In liposarcoma, AKT-mediated phosphorylation of IWS1 promotes the maintenance of cancer stem cells, contributes to a "metastable" cell phenotype, and is associated with reduced overall survival in patients [3].

In summary, Iws1 plays essential roles in multiple biological processes such as parasite survival in host cells, embryonic development, and cancer cell biology. The study of Iws1 through KO/CKO mouse models has provided insights into its functions in these specific disease areas, including parasite-host interactions, embryonic development, and liposarcoma [1,2,3].