Influence of BANK1 in the in vivo development of lupus
BANK1 (B-cell scaffold protein with ankyrin repeats) is an adaptor molecule that functions as a scaffold for other molecules, such as kinases or phospholipases, to aid in their function during signaling events. Because of its tyrosine residues and multiple interacting domains, BANK1 is able to physically bind with a variety of proteins. Therefore it is predicted that BANK1 could impact signaling pathways important in B cell activation. BANK1 contains a putative toll/interleukin-1 (TIR) domain and thus may be involved in TLR signaling.Our preliminary data suggests that the genetic association in the BANK1 gene localizes to the 2d exon, where in addition to another disruptive and rare mutation, the non-synonymous R61H variant is found. The TIR domain locates to the N-terminus that is coded by exon 2 . Thus, we hypothesize that the increased expression of the TIR conformational domain coded by the human BANK1 exon 2 associates with lupus risk, and is of great relevance to disease development. In support , we have recently observed that deficiency of BANK1 in mice leads specifically to low activity of p38 mitogen activated protein kinase (MAPK) following CpG activation, which results in reduced activity of the MNK1/2 kinase and reduced translation of IL-6 protein due to reduced activation of the translation initiation factor EIF4E, a direct target of MNK1/2. In addition, we have evidence showing that in Bank1 deficiency decreases IgG anti-dsDNA antibody production and IgG+ plasma cells in lupus prone mice. Thus, we hypothesize that increased expression of the TIR conformational domain coded by the human BANK1 exon 2 associates with lupus risk. We therefore suggest that overexpression of BANK1 promote the development of lupus phenotypes and disease in vivo. Also, we suggest that functional genetic variants of BANK1 within exon 2 alter TIR-dependent BANK1 signaling function and IL6 production. We propose the following aims:
Specific aim 1: To define if over-expression of human BANK1 impacts lupus development in vivo through increased production of IL6. Increased expression of BANK1 with R61 associates with risk, and we have developed a transgenic mouse line for human BANK1 to determine its effects on cellular phenotypes, and disease development in vivo.
Specific aim 2: To study the effect of the human BANK1 W40C mutation in the production of IL6 and p38 signaling in vitro. To define how a human mutation affects signaling events in B cells. We will develop a mouse line using zinc finger nuclease technology (ZFN) and analyze the differential impact on signaling.
Specific aim 3: To define if the translation initiation inhibitor, Pateamine A suppress IL-6 and autoantibody production in vitro and disease in vivo.