Fig. 2: Mice with hepatic deletion of FNDC4 exhibited decreased circulating levels of sFNDC4 and developed a pre-diabetes phenotype.

a Schematic representation of the study protocol. b RT-qPCR quantification of Fndc4 mRNA at the indicated tissues (n = 5 mice per group for the liver and skeletal muscle (gastrocnemius) and n = 7 mice per group for gonadal white adipose tissue (gWAT). c Western blot against FNDC4 protein in the liver and VCP as loading control (n = 2 mice per group are shown). Results on additional mice and uncropped blots are shown in Source data. d ELISA quantification of plasma (trunk blood) sFNDC4 (n = 5 mice per group), 3 weeks post intravenous (iv) injection of AAVs. e RT-qPCR quantification of Fndc4 mRNA at the indicated tissues (n = 5 mice for Liver ChowAAVshControl, Liver HFDAAVShFNDC4, n = 4 mice for Liver ChowAAVshFNDC4, and n = 6 mice for Liver HFDAAVshControl, gWAT ChowAAVshControl, gWATChowAAVshFNDC4, gWAT HFDAAVshControl, gWAT HFDAAVshFNDC4, Sk.muscle ChowAAVshControl, Sk.muscle ChowAAVshFNDC4, Sk.muscle HFDAAVshControl, Sk.muscle HFDAAVshFNDC4). Skeletal muscle is gastrocnemius. For b, e, 2^ddCt values are shown, which are expressed relative to the Sk.muscle group. Hprt is used as a housekeeping gene for liver and gWAT and H3f3 is used as a housekeeping gene for Sk.muscle. f ELISA quantification of plasma (trunk blood) sFNDC4 (n = 8 mice ChowAAVshControl, n = 6 mice ChowAAVshFNDC4, n = 7 mice HFDAAVshControl, n = 8 mice HFDAAVshFNDC4) 11 weeks post iv injection of AAVs and 8 weeks on HFD or chow control diet. Statistics represent unpaired two-tailed t test. Data point in square was not taken into account for the statistics, due to very high levels of sFNDC4 compared to the rest of the mice in the group (outlier). Glucose homeostasis in chow and HFD fed mice: g blood glucose and h plasma insulin levels during an IPGTT. i blood glucose levels during an ITT on chow-fed mice. j Blood glucose levels, k area under the curve (refers to j), and l plasma insulin during an IPGTT on HFD-fed mice (weeks on HFD as shown on graph). m Blood glucose levels during an ITT on HFD-fed mice. In g, h, j, m, n = independent mice and the exact number of mice is shown on the figure. Male, C57BL6N mice were put on HFD when 10–11 weeks old and compared with age-matched chow fed mice. HFD contained 45% fat. During IPGTT and glucose-induced insulin test, 2 g/kg d-glucose was injected (ip) and during ITT 0.8 U/kg insulin was used (ip). p p-value, ns non-significant. Data shown are mean ± SEM. Statistics in b, d–f, h, j–m represent an unpaired, two-tailed Student’s t test. Source data are provided as a Source data file.