BMX and its role in inflammation, cardiovascular disease, and cancer

Bone marrow kinase on chromosome X (BMX) is a cytosolic tyrosine kinase and a member of the TEC kinase family. BMX is expressed in hematopoietic cells of the myeloid lineage where it participates in the immune response. It is also involved in the response to ischemia and pressure overload in the endocardium and the cardiac endothelium. Moreover, BMX is expressed in several types of cancers and very recently has been shown to mediate the survival and tumorigenicity of glioblastoma cancer stem cells. In the inflammatory response BMX regulates the secretion of proinflammatory cytokines induced by TNFα, IL-1β, and TLR agonists. It is required for the activation of the MAP kinase and NFκB pathways and acts at the level of the essential TAK1/TAB complex. Cellular regulation of the IL-8 promoter by BMX is dependent on membrane localization mediated by its pleckstrin homology domain, as well as on BMX kinase activity. BMX deficiency confers protection from arthritis in a mouse model known to be dependent on macrophages and IL-1β. Genetic replacement of BMX with a kinase-inactive allele surprisingly restored susceptibility to arthritis, suggesting that in vivo BMX kinase activity can be dispensable. This review summarizes recent advances in the knowledge of BMX biology and their relevance for translational medicine.