Identification and characterization of SKAT‐2, a novel Th2‐specific zinc finger gene

We have identified a novel Kruppel‐type zinc finger (ZF) gene, SKAT‐2, which is selectively expressed by murine Th2 cells. The protein encoded by this gene has 14 C2H2‐type ZF tandemly arrayed at its C terminus and N‐terminal SCAN box and KRAB domains. SKAT‐2 is tissue restricted in expression at the RNA level, detectable only in brain and at low levels in kidney and spleen and few hematopoietic cell lines. By in situ hybridization, SKAT‐2 expression was found to peak in antigen‐stimulated CD4+ T cells after 2–3 days of culture under Th2 but not Th1 biasing conditions. This pattern of expression closely mirrored that of GATA‐3 in the same cells. In transient transfection experiments in phorbol 12‐myristate 13‐acetate/ionomycin‐stimulated EL4 cells, SKAT‐2 was found to up‐regulate the activity of the IL‐4 but not the IL‐5 promoter, contrasting with the ability of GATA‐3 to activate both promoters. This result was confirmed using clones of EL4 cells stably expressing an inducible form of SKAT‐2, thus SKAT‐2 is a novel Th2‐specific gene that may play a role in selective regulation of cytokine genes in T cells.