Fig. 5.

PARP14, the metabolic response, and survival. (A) IL-4 increases protein synthesis in B cells. Mean (±SEM) incorporation of [³⁵S]methionine into WT B cells after a 3-h culture in the presence or absence of IL-4; where indicated, cells were pretreated 30 min with inhibitor. (B and C) AMPK inhibition attenuates glycolysis (B) and survival (C) of IL-4–treated B cells. Shown are the mean (±SEM) results of glycolysis and TUNEL assays of B cells pretreated with AMPK inhibitor (compound C; 1 μM) and then cultured ±IL-4. (D–H) AMPK activation in Parp14-null B cells reverses their defects of glycolysis and B-cell rescue by IL-4. (D and E) Activated B cells were transduced with MIT, MIT-AMPK-DN, or MIT-AMPK-CA retrovectors. Glycolysis (D) or apoptosis (E) of purified Thy1.1⁺ (transduced) B cells was then assayed after culture ±IL-4 (20 h). (F) Activation of AMPK and ACC in WT and Parp14-null B cells. Purified B cells (WT and Parp14^−/−) were stimulated with IL-4 (2 h) or metformin, after pretreatment (30 min) with compound C as indicated. ΦNX cells treated with oligomycin (30 min) were used as a positive control. Shown are results of immunoblots using anti-pAMPK (T172) and anti-pACC (S79) along with anti-AMPK and anti-ACC as loading controls. (G and H) Effect of metformin on IL-4–enhanced glycolysis (G) and survival (H) of Parp14 KO B cells. After 20 h culture in IL-4, metformin, or both, glycolysis and apoptosis were assayed; data shown are as in B and C.