We also observed that the LD structure is disrupted in knockout adipocytes and ER structure defects in Prmt5AKO eWAT. homeostasis and function. Deletion of disrupts fatty acid metabolism and impairs lipid droplet biogenesis in white adipocytes, which causes age\dependent fat loss and lipodystrophy, and eventually leads to insulin resistance and systemic metabolic syndrome. Mechanically, PRMT5 controls lipid droplet formation through methylation of SPT5, which transcriptionally regulates expression. Meanwhile, PRMT5 promotes fatty acid biosynthesis through targeting SRBEP1a. Our study for the first time reports the physiological function of PRMT5 in AT and identifies a novel regulatory pathway controlling gene expression and LD biogenesis, SREBP1a and lipid metabolism. These results O6BTG-octylglucoside provide insights into the role of PRMT5 in lipid metabolism, lipodystrophy and non\obese T2D. 2.?Results 2.1. Adipocyte\Specific Knockout of Leads to Age\Dependent Losses in Fat Mass To investigate the role of PRMT5 in adipocytes, we generated adipocyte\specific knockout mice by crossing the mice with mice (Figure? 1a). In the Prmt5AKO mice, the exon 7 of is deleted, leading to premature translational stop and generation of a truncated peptide lacking the key functional domains including the methyltransferase (MTase) domain (Figure?1a). In this model, should be deleted exclusively in adipocytes as specifically marks all mature O6BTG-octylglucoside adipocytes.[ 19 ] We confirmed the efficient and specific reduction of PRMT5 protein levels in both BAT and WAT by Western blotting (Figure?1b), but not in muscle tissues (Figure?S1a, Supporting Information). We also confirmed that mRNA levels of were specifically reduced in mature adipocytes but not in SVF preadipocytes that do not express (Figure?S1b, Supporting Information). Open in a separate window Figure 1 Adipocyte\specific knockout of (Prmt5AKO) leads to loss of fat mass in white adipose tissues. a) Targeting strategy for conditional knockout of Prmt5. Upper: gene structure showing exons (blue boxes), LoxP insertions (red triangles) and 5 and 3 untranslated regions (orange boxes). Middle: PRMT5 protein domain structure with amino acids numbers labeled. MTase is the catalytic domain. Lower: Cre\mediated excision of LoxP\flanked exon results in reading frame shift and a premature translational stop codon, generating a truncated protein containing only partial of the TM barrel domain. b) Efficient reduction of PRMT5 protein levels in epididymal White Adipose Tissue (eWAT) and inguinal White Adipose Tissue (iWAT), and brown adipose tissue (BAT) of the 2 2 month old male Prmt5AKO (AKO) mice. c) Representative images of male WT (Prmt5flox/flox) and Prmt5AKO mice at 10 month old (left panel), showing progressive reduction in body weight of the Prmt5AKO mice relative to WT mice (right panel). d) Prmt5AKO leads to progressive loss of total body fat, relative to fat mass in WT mice. c,d) = 8, 6, and 4 pairs of male mice for 3\, 6\, and 10\month\old, respectively. e) Representative images of BAT and WAT depots from male mice showing progressive mass reduction of KO WAT with age. f,h,j) Weights of various BAT and WAT (iWAT, eWAT and anterior subcutaneous White Adipose Tissue, asWAT) depots from male mice at different ages, as shown in (e). g,i,k) H&E staining of eWAT sections from WT (Prmt5flox/flox) and Prmt5AKO male mice at 3, 6, and 10month old. Scale bar: 50?m. MAPT Data represent mean s.e.m. (= 8 and 9 pairs of mice for male and female O6BTG-octylglucoside mice, respectively. c) Body weight, fat mass, and O6BTG-octylglucoside muscle mass of male (upper) and female (lower) WT (Prmt5flox/flox) and Prmt5AKO mice after 12 week of HFD feeding. = 8 and 4 pairs of mice for male and female mice, respectively. d) WAT and BAT absolute weights from male (upper panel) and female (lower panel) WT (Prmt5flox/flox) and Prmt5AKO mice after 12?week of HFD, = 5 pairs of mice. e) H&E staining of eWAT sections from male WT (Prmt5flox/flox) and Prmt5AKO mice after 12 week of HFD. Scale bar: 50?m. Data represent mean s.e.m. (= 8, 8, and 7 pairs of mice for 3, 6, and 10C12 month old, respectively. dCf) Percentage changes of blood glucose concentrations during insulin tolerance tests (ITT) performed on d) 3\, e) 6\, and f) 10C12 month old male WT (Prmt5flox/flox) and Prmt5AKO mice (left). Area O6BTG-octylglucoside above curve (AAC) calculated based on data in left panel (right). = 6, 6, and 7 pairs of mice for 3, 6, and 10C12 month old, respectively. g) Blood glucose concentrations during glucose tolerance tests (GTT) performed on male WT (Prmt5flox/flox) and Prmt5AKO mice after 8 week of HFD (left). AUC calculated based on data in left panel (right), = 8.