In vitro activity: GSK J4 HCl is an ethyl ester derivative of the JMJD3 selective histone demethylase inhibitor GSK-J1 with an IC50 value greater than 50 μM in vitro. GSK J4 HCl is used to probe the consequences of demethylation of H3K27me3. In human primary macrophages, GSK-J4 inhibits the lipopolysaccharide-induced production of cytokines, including pro-inflammatory tumour necrosis factor (TNF). In addition, GSK-J4 prevents the lipopolysaccharide-induced loss of H3K27me3 associated with the TNF transcription start sites and blocked the recruitment of RNA polymerase II.

Kinase Assay: Jumonji C domain-containing histone demethylases (JHDMs) are Fe(II) and α-ketoglutarate dependent enzymes that oxygenate methylated histone lysine residues and thereby cause their demethylation. GSK-J1 is selective for the KDM6 subfamily members JMJD3 and UTX with an IC50 of 60 nM in a JMJD3 assay, and is inactive against other demethylases of the JMJ family and over 100 tested kinases and histone deacetylases. The prodrug GSK-J4 inhibited TNF-α production with an IC50 of 9 μM in LPS-stimulated human macrophages and blocked the production of TNF-α by macrophages derived from patients with rheumatoid arthritis. GSK J4 is an inhibitor of JMJD3 and UTX.

Cell Assay: GSK J4 inhibited TNF-α protein production in a dose-dependent manner, with an IC50 value of 9 μM. Cells used: Human primary macrophages