Fig. 3: Every second day, injections of rec. FcsFNDC4 0.2 mg/kg improved glucose tolerance and increased glucose uptake specifically in the white adipose tissue.

a Plasma (trunk) sFNDC4 in mice on 16 weeks HFD (n = 4 independent mice per time point) and Chow control mice (n = 2–4 independent mice per time point). Statistics represent a regular two-way ANOVA for diet (Pdiet) and time (Pzt). Multiple comparisons for diet effect were performed according to Holm–Sidak’s test and exact p values are shown for chow–HFD diet comparison for each time point. b RT-qPCR quantification of liver Fndc4 mRNA at 16 weeks HFD and Chow mice (n = 4 mice per group). c Plasma (trunk) sFNDC4 ng/ml from chow and 14 weeks HFD, 48 h after a single ip injection of FcsFNDC4 (0.2 mg/kg) or VC (n = 6 mice per group for Chow VS and HFD VC, n =7 mice per goup for HFD FcsFNDC4). d Blood glucose during IPGTT test, e area under the curve (AUC), f glucose-stimulated insulin response (during the IPGTT) in d, e (d–f n = 7 mice per group), and g percentage of blood glucose levels during an ITT using 0.8 U/kg insulin ip, (VC—n = 6 mice, FcsFNDC4—n = 7 mice) on HFD, 2 and 4 weeks injected with VC or FcsFNDC4. h Quantification of 2-NBDG glucose content at shown tissues, 35 min after ip 2-NBDG injection (n = 4–6 mice per group, exact numbers per group are provided in Source data). i Western blot of pAKT(Ser473) and total AKT at the indicated tissues, after an acute injection of insulin. pAKT and AKT were run on different blots, with VCP and beta actin as loading controls, respectively. This experiment was performed once under the exact same conditions. j Mean cell size of adipocytes and k percentage of Cd68-positive area of gWAT (j, k VC—n = 6 mice, FcsFNDC4—n = 8 mice). l Representative images (out of 20 images per mouse, VC—n = 6 mice, FcsFNDC4—n = 8 mice) for hematoxylin and eosin (H&E) and anti-Cd68 staining of gWAT. Scale bar = 200 µm. m, n RT-qPCR quantification of mRNA levels of the presented genes in gWAT (VC—n = 6 mice and FcsFNDC4—n = 8 mice). Data shown represent 2^ddCt values. H3f3 was used as a housekeeping gene. ELISA quantification of o plasma TNFalpha (VC—n = 6 mice and FcsFNDC4-—n = 7 mice) and p serum resistin (VC—n = 6 mice and FcsFNDC4—n = 9 mice). For h–p HFD mice, 4 weeks injected with VC or FcsFNDC4 are shown. HFD contained 60% fat and it was initiated at 7–8 weeks of age. Mice were males, C57BL6N. Data shown are mean ± SEM. Statistics are unpaired, two-sided t test. p p-value, ns non-significant. Source data are provided as a Source data file.