Role of class IA phosphoinositide 3-kinase in B lymphocyte development and functions

PI3K (phosphoinositide 3-kinase) family members control a variety of cellular responses, such as cell growth, survival, cytoskeletal remodelling and the trafficking of intracellular organelles, in many cell types, including lymphocytes. It has been difficult to evaluate the roles of distinct PI3Ks in immune responses, because specific inhibitors for each PI3K are lacking and most stimuli activate multiple PI3Ks. The development of gene-targeted mice has now allowed the elucidation of roles played in vivo by PI3K species in the immune system. Studies on mice deficient in catalytic as well as regulatory subunits of class IA PI3Ks have shown the importance of this class of PI3K in B lineage cells. Here I discuss the role of class IA PI3Ks in B lymphocyte development and B cell antigen receptor-mediated signal transduction.