PT - JOURNAL ARTICLE AU - Zilu Zhu AU - Ashima Shukla AU - Parham Ramezani-Rad AU - John R Apgar AU - Robert C Rickert TI - The AKT isoforms 1 and 2 drive B cell fate decisions during the germinal center response AID - 10.26508/lsa.201900506 DP - 2019 Dec 01 TA - Life Science Alliance PG - e201900506 VI - 2 IP - 6 4099 - https://www.life-science-alliance.org/content/2/6/e201900506.short 4100 - https://www.life-science-alliance.org/content/2/6/e201900506.full SO - Life Sci. Alliance2019 Dec 01; 2 AB - The PI3K pathway is integral for the germinal center (GC) response. However, the contribution of protein kinase B (AKT) as a PI3K effector in GC B cells remains unknown. Here, we show that mice lacking the AKT1 and AKT2 isoforms in B cells failed to form GCs, which undermined affinity maturation and antibody production in response to immunization. Upon B-cell receptor stimulation, AKT1/2–deficient B cells showed poor survival, reduced proliferation, and impaired mitochondrial and metabolic fitness, which collectively halted GC development. By comparison, Foxo1T24A mutant, which cannot be inactivated by AKT1/2 phosphorylation and is sequestered in the nucleus, significantly enhanced antibody class switch recombination via induction of activation-induced cytidine deaminase (AID) expression. By contrast, repression of FOXO1 activity by AKT1/2 promoted IRF4-driven plasma cell differentiation. Last, we show that T-cell help via CD40, but not enforced expression of Bcl2, rescued the defective GC response in AKT1/2–deficient animals by restoring proliferative expansion and energy production. Overall, our study provides mechanistic insights into the key role of AKT and downstream pathways on B cell fate decisions during the GC response.