Fig. 1: Glucose reabsorption in WT kidney epithelial cells is regulated by fasting and refeeding.

Female and male WT mice were fed a chow diet and were fasted starting at 12:00 h or at 24:00 h for 24 h, or refed with normal chow for 8 h after 24 h fasting. A BBMVs prepared from chow-fed WT mice at 12:00 h or at 24:00 h were incubated with [¹⁴C]-αMG for 120 min to measure glucose uptake. Mean ± SD, n = 4, unpaired t-test. ZT: zeitgeber time. B 2-NBDG uptake was measured in WT RPTECs cultured in 10% FBS-containing medium (F0) or serum-free medium for 48 h (F48), then refed with 20% FBS-containing medium for 8 h (Refed). Mean ± SD, (n = 4), unpaired t-test, two-tailed. C Hk2 cells were cultured in serum-containing medium (F0) or serum free medium for 48 h (F48), then refed with 20% FBS containing medium for 8 h and used to measure 2-NBDG uptake. Mean ± SD, (n = 4), unpaired t-test, two-tailed. mRNA (D, n = 4–6 animals/group) and protein (E, n = 3/group) levels in the kidney cortex (KC) collected at 12:00 h or at 24:00 h. Mean ± SD, multiple unpaired t-tests. WT RPTECs were subjected to fasting/feeding protocol and used to measure mRNA (F, n = 6) and protein (G, n = 3) levels. Mean ± SD, multiple unpaired t-tests. mRNA expression (H, n = 6), and protein (I, n = 3) levels were measured in Hk2 cells subjected to fasting/refeeding protocol. Mean ± SD, multiple unpaired t-tests. J WT RPTECs were transfected with siSglt2, subjected to fasting/refeeding protocols, and used to measure 2-NBDG uptake. Mean ± SD, n = 4/group. # p < 0.05, ## p < 0.01 and ### p < 0.001, unpaired two-tailed t-test. Nrf1 mRNA levels in the renal cortex were measured (K). Mean ± SD, n = 4–6. Nuclear proteins were measured in the kidney cortex collected at 12:00 h or at 24:00 h (L). Mean ± SD, n = 3/group, unpaired two-tailed t-test. *p < 0.05, **p < 0.01 and ***p < 0.001 compared with F0; # p < 0.05, ## p < 0.01 and ### p < 0.001 vs. F24; @ p < 0.05, @@ p < 0.01 and @@@ p < 0.001 vs. F48. ZT Zeitgeber time.