title: Adiponectin is partially associated with exosomes in mouse serum.
abstract: Exosomes are membrane vesicles 30-120 nm in diameter that are released by many cell types and carry a cargo of proteins, lipids, mRNA, and microRNA. Cultured adipocytes reportedly release exosomes that may play a role in cell-to-cell communication during the development of metabolic diseases. However, the characteristics and function of exosomes released from adipocytes in vivo remain to be elucidated. Clearly, adipocyte-derived exosomes could exist in the circulation and may be associated with adipocyte-specific proteins such as adipocytokines. We isolated exosomes from serum of mice by differential centrifugation and analyzed adiponectin, leptin, and resistin in the exosome fraction. Western blotting detected adiponectin but no leptin and only trace amounts of resistin in the exosome fraction. The adiponectin signal in the exosome fraction was decreased by proteinase K treatment and completely quenched by a combination of proteinase K and Triton X-100. Quantitative ELISA showed that the exosome fraction contains considerable amounts of adiponectin, but not leptin or resistin. The concentration of adiponectin in the serum and the ratio of adiponectin to total protein in the exosome fraction were lower in obese mice than in lean mice. These results suggest that a portion of adiponectin exists as a transmembrane protein in the exosomes in mouse serum. We propose adiponectin as a marker of exosomes released from adipocytes in vivo.
authors.affiliation: Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
authors.forename: Worrawalan
authors.initials: W
authors.lastname: Phoonsawat
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan; Functional Biomolecules Research Group, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-0901, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Aoki-Yoshida
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsuruta
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan. Electronic address: ksnym@chem.agr.hokudai.ac.jp.
authors.forename: Kei
authors.initials: K
authors.lastname: Sonoyama
mesh_terms: D017667:Adipocytes / Q000378:metabolism; D052242:Adiponectin / Q000097:blood* / Q000737:chemistry; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000737:chemistry; D055354:Exosomes / Q000378:metabolism*; D020738:Leptin / Q000097:blood; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D008970:Molecular Weight; D009765:Obesity / Q000097:blood; D052243:Resistin / Q000097:blood; D060149:Tetraspanin 30 / Q000097:blood
chemical_list: D052242:Adiponectin; C499919:Adipoq protein, mouse; D015415:Biomarkers; C554587:Cd63 protein, mouse; D020738:Leptin; D052243:Resistin; C499623:Retn protein, mouse; D060149:Tetraspanin 30
keywords: Adiponectin; Exosome; Leptin; Mice; Resistin