Fig 2: Ppp2r5d knockdown decreases PP2A activity and increases glucose uptake in SNRK knockout primary brown adipocytes and 3T3-L1 cells. A–C: PPP2R5D gene expression (A), PP2A activity (B), and glucose uptake (C) in SNRK knockout primary brown adipocytes (PBASNRK-/-) treated with Ppp2r5d siRNA or non-targeting siRNA (n = 3). D–F: Ppp2r5d gene expression (D), PP2A activity (E), and glucose uptake (F) in SNRK knockout 3T3-L1 cells (3T3-L1SNRK-/-) treated with Ppp2r5d siRNA or non-targeting siRNA (n = 3). t test was used in panels A, B, D, & E, and two-way ANOVA followed by Bonferroni post hoc test in Figure 6C,F. *P < 0.05, **P < 0.01, and ***P < 0.001 as indicated.

Fig 3: Enhanced PP2A activity in SNRK deficient brown and white adipose tissues. A: PP2A activity in SNRK knockout primary brown adipocytes (PBASNRK-/-) and control cells (PBAWT/WT). B: PP2A activity in SNRK knockout 3T3-L1 cells (3T3-L1SNRK-/-) and control cells (3T3-L1WT/WT) (n = 3). C: PP2A activity in brown adipose tissue of SNRK-/-,U-Cre and littermate controls (SNRKLoxp/Loxp and SNRKU-Cre) (n = 9–11). D–E: PP2A activity in white (D) and brown (E) adipose tissues of SNRK-/-,A-Cre and littermate controls (SNRKLoxp/Loxp and SNRKA-Cre) (n = 7–10). t test was used in panels C & E, and one-way ANOVA followed by Bonferroni post hoc test in panels A, B, & D. *P < 0.05, **P < 0.01, and ***P < 0.001 as indicated.

Fig 4: Hypothetical model of SNRK and insulin resistance. SNRK deficiency in white adipose tissue (WAT) causes both local and systemic insulin resistance through increasing inflammation [9] and decreasing insulin-induced glucose uptake. However, SNRK deficiency in brown adipose tissue (BAT) results in decreased insulin-induced glucose uptake only and local but not systemic insulin resistance. Yellow and blue arrows indicate inflammation and insulin signaling pathways, respectively.

Fig 5: Increased AKT -PPP2R5D-PP2AC interaction in SNRK deficient brown and white adipose tissues. A: Co-immunoprecipitation of AKT, PPP2R5D, and PP2AC in SNRK knockout primary brown adipocytes (PBASNRK-/-) and control cells (PBAWT/WT). B–C: Co-immunoprecipitation of PPP2R5D, SNRK, and PP2AC in brown (B) and white (C) adipose tissues of SNRKloxp/loxp and SNRKA-Cre mice. D: Co-immunoprecipitation of AKT, PPP2R5D, and PP2AC in brown adipose tissue of SNRK-/-,U-Cre and littermate controls. E–F: Co-immunoprecipitation of AKT, PPP2R5D, and PP2AC in brown (E) and white (F) adipose tissues of SNRK-/-,A-Cre and littermate controls.