Fig. 1: Grasp55^−/− mice display reduced fat mass and resistance to high-fat diet-induced obesity.

a Knockout strategy for the Grasp55 locus. The reporter-neo cassette replaced all 11 exons of mouse Grasp55. Red triangles indicate the location of loxP sites. More detailed diagrams are provided in the Supplementary Fig. 1. b Expressions of GRASP55 and GRASP65 in major organs were examined by immunoblotting. The amount of β-actin protein was monitored as a cytosolic protein loading control. c Survival curves of wild-type (Grasp55^+/+) and Grasp55^−/− male mice over 40 weeks (n = 15). d Photographs of Grasp55^+/+ and Grasp55^−/− mice at postnatal day 28. e Body weight curves of male mice fed normal diet (ND, left) and high-fat diet (HFD, right) at 1–30 weeks of age (n = 15). The arrow indicates the initiation time of HFD at 6 weeks of age. The body weight curve of the Grasp55^+/+ mice fed ND was replotted in the HFD graph (open circle, right) for comparison. f The relative fat mass ratio (fat/body weight) of 16-week-old male mice fed ND and after HFD for 4 weeks (n = 5–7). g–j Gross and histological examinations of epididymal white adipose tissue (EWAT). Ventral view (g) and wet weights (h) of EWAT (right side) of male mice at 18 weeks of age fed on ND and after HFD for 12 weeks (n = 6). Arrows indicate epididymal fat tissues. Representative light microscopic tissue images (H&E staining) are presented in (i). Quantitative analyses of the H&E images, that inversely correlate with fat contents of EWAT by counting the number of adipocyte nuclei in a light microscopic field (450 × 340 μm), are depicted in (j, n = 10). Unprocessed blots are presented in Supplementary Fig. 22. Data are shown as mean ± SEM. Scale bars: 50 μm. **p < 0.01. All p values were calculated by unpaired two-tailed Student’s t tests. Source data are provided as a Source Data file.