Pathogenic CARD11 mutations cause aberrant nuclear factor κB (NF-κB) activation, which is presumably responsible for multiple immunological disorders. However, whether there is an NF-κB–independent regulatory mechanism contributing to CARD11 mutations related to pathogenesis remains undefined. Using three distinct genetic mouse models, the Card11 knockout (KO) mouse model mimicking primary immunodeficiency, the CARD11 E134G point mutation mouse model representing BENTA (B cell expansion with NF-κB and T cell anergy) disease, and the mouse model bearing oncogenic K215M mutation, we show that CARD11 has a noncanonical function as a negative regulator of the AKT-FOXO1 signal axis, independent of NF-κB activation. Although BENTA disease–related E134G mutant elevates NF-κB activation, we find that E134G mutant mice phenotypically copy Card11 KO mice, in which NF-κB activation is disrupted. Mechanistically, the E134G mutant causes exacerbated AKT activation and reduced FOXO1 protein in B cells similar to that in Card11 KO cells. Moreover, the oncogenic CARD11 mutant K215M reinforces the importance of the noncanonical function of CARD11. In contrast to the E134G mutant, K215M shows a stronger inhibitory effect on AKT activation and more stabilized FOXO1. Likewise, E134G and K215M mutants have converse impacts on B cell development and differentiation. Our results demonstrate that, besides NF-κB, CARD11 also governs the AKT/FOXO1 signaling pathway in B cells. The critical role of CARD11 is further revealed by the effects of pathogenic CARD11 mutants on this noncanonical regulatory function on the AKT-FOXO1 signaling axis.

致病的CARD11突变会导致异常的核因子κB（NF-κB）激活，这可能是导致多种免疫系统疾病的原因。但是，是否存在不依赖于NF-κB的调控机制导致与发病机理相关的CARD11突变仍未确定。使用三种不同的遗传小鼠模型，Card11模仿原发性免疫缺陷的基因敲除（KO）小鼠模型，代表BENTA（带有NF-κB和T细胞无反应性的B细胞扩增）疾病的CARD11 E134G点突变小鼠模型以及带有致癌性K215M突变的小鼠模型，我们证明了CARD11具有非规范性充当AKT-FOXO1信号轴的负调节器，与NF-κB激活无关。尽管与BENTA疾病相关的E134G突变体提高了NF-κB的激活，但我们发现E134G突变体小鼠在表型上复制了Card11 KO小鼠，其中NF-κB的激活被破坏了。机械地，所述突变体E134G加剧原因AKT活化和降低FOXO1蛋白在B细胞类似于CARD11KO细胞。此外，致癌的CARD11突变体K215M增强了CARD11非规范功能的重要性。与E134G突变体相反，K215M对AKT激活具有更强的抑制作用，并且FOXO1更稳定。同样，E134G和K215M突变体对B细胞的发育和分化也有相反的影响。我们的结果表明，除NF-κB外，CARD11还控制B细胞中的AKT / FOXO1信号传导途径。致病性CARD11突变体对AKT-FOXO1信号轴上这种非规范调节功能的影响进一步揭示了CARD11的关键作用。