Anti-ZXDC polyclonal antibody

The transcription of major histocompatibility complex class II (MHC II) genes is dependent on the co-activator protein class II trans-activator (CIITA). We have recently identified a protein known as zinc finger X-linked duplicated family member C (ZXDC) that, along with its binding partner ZXDA, forms a complex that interacts with CIITA and regulates MHC II transcription. Western blot analysis with anti-ZXDC antibodies identified two species of the ZXDC protein, one migrating near its predicted molecular mass and one with slower electrophoretic mobility. We report here that the slower migrating form is the result of sumoylation at a single lysine residue within the transcriptional activation domain of ZXDC. Three SUMO proteins (SUMO-1, -2 and -3) can modify the ZXDC protein. Multiple SUMO E3 ligase enzymes and HDAC4 can facilitate ZXDC sumoylation, and one ligase, PIASy, interacts with a specific region of the ZXDC protein. We found that sumoylation does not appear to disrupt or modulate the interaction of ZXDC with its binding partners. Rather, sumoylation of ZXDC is required for full activity of the transcriptional activation domain. Our findings suggest that sumoylation is an important regulator of ZXDC.

There is a large inter-individual variability in the response to Mycobacterium tuberculosis infection. In previous linkage analyses, we identified a major locus on chromosome region 8q controlling IFN-gamma production after stimulation with live BCG (Bacillus Calmette-Guerin), and a second locus on chromosome region 3q affecting IFN-gamma production triggered by the 6-kDa early secretory antigen target (ESAT-6), taking into account the IFN-gamma production induced by BCG (IFN gamma-ESAT6(BCG)). High-density genotyping and imputation identified similar to 100,000 variants within each linkage region, which we tested for association with the corresponding IFN-gamma phenotype in families from a tuberculosis household contact study in France. Significant associations were replicated in a South African familial sample. The most convincing association observed was that between the IFN gamma-ESAT6(BCG) phenotype and rs9828868 on chromosome 3q (p = 9.8 x 10(-6) in the French sample). This variant made a significant contribution to the linkage signal (p < 0.001), and a trend towards the same association was observed in the South African sample. This variant was reported to be an eQTL of the ZXDC gene, biologically linked to monocyte IL-12 production through CCL2/MCP1. The identification of rs9828868 as a genetic driver of IFN gamma production in response to mycobacterial antigens provides new insights into human anti-tuberculosis immunity.