title: CD109 is a component of exosome secreted from cultured cells.
abstract: Exosomes are 50-100-nm-diameter membrane vesicles released from various types of cells. Exosomes retain proteins, mRNAs and miRNAs, which can be transported to surrounding cells. CD109 is a glycosylphosphatidylinositol-anchored glycoprotein, and is released from the cell surface to the culture medium in vitro. Recently, it was reported that secreted CD109 from the cell surface downregulates transforming growth factor-β signaling in human keratinocytes. In this study, we revealed that CD109 is a component of the exosome in conditioned medium. FLAG-tagged human CD109 (FLAG-CD109) in conditioned medium secreted from HEK293 cells expressing FLAG-CD109 (293/FLAG-CD109) was immunoprecipitated with anti-FLAG affinity gel, and the co-precipitated proteins were analyzed by mass spectrometry and western blotting. Exosomal proteins were associated with CD109. We revealed the presence of CD109 in exosome fractions from conditioned medium of 293/FLAG-CD109. Moreover, the localization of CD109 in the exosome was demonstrated using immuno-electron microscopy. When we used HEK293 cells expressing FLAG-tagged truncated CD109, which does not contain the C-terminal region, the association of truncated CD109 with exosomes was not detected in conditioned medium. These findings indicate that CD109 is an exosomal protein and that the C-terminal region of CD109 is required for its presence in the exosome.
authors.affiliation: Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sakakura
authors.affiliation: Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Mii
authors.affiliation: Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Head and Neck Surgery, Aichi Cancer Center Hospital, Nagoya, Japan.
authors.forename: Sumitaka
authors.initials: S
authors.lastname: Hagiwara
authors.affiliation: Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Hibi
authors.affiliation: Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan. Electronic address: mtakaha@med.nagoya-u.ac.jp.
authors.forename: Masahide
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Pathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan. Electronic address: murakumo@med.kitasato-u.ac.jp.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Murakumo
mesh_terms: D015703:Antigens, CD / Q000737:chemistry*; D003470:Culture Media / Q000378:metabolism*; D055354:Exosomes / Q000378:metabolism*; D058851:GPI-Linked Proteins / Q000737:chemistry / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D015703:Antigens, CD; C120523:CD109 protein, human; D003470:Culture Media; D058851:GPI-Linked Proteins; D009363:Neoplasm Proteins
keywords: CD109; Exosome; Mass spectrometry