title: Antigen-presenting cells in parotid glands contain cystatin D originating from acinar cells.
abstract: Cystatin D encoded by Cst5 is a salivary classified type II cystatin. We investigated the dynamism of cystatin D by examining the distribution of cystatin D protein and mRNA in rats, to identify novel functions. The simultaneous expression of Cst5 and cystatin D was observed in parotid glands, however in situ hybridization showed that only acinar cells produced cystatin D. Synthesized cystatin D was localized in small vesicles and secreted from the apical side to the saliva, and from the basolateral side to the extracellular region, a second secretory pathway for cystatin D. We also identified antigen-presenting cells in the parotid glands that contained cystatin D without the expression of Cst5, indicating the uptake of cystatin D from the extracellular region. Cystatin D was detected in blood serum and renal tubular cells with megalin, indicating the circulation of cystatin D through the body and uptake by renal tubular cells. Thus, the novel dynamism of cystatin D was shown and a function for cystatin D in the regulation of antigen-presenting cell activity was proposed.
authors.affiliation: Department of Biochemistry, The Nippon Dental University, School of Life Dentistry at Niigata, 1-8 Hamaura-cho, Niigata 951-8580, Japan. nashida@ngt.ndu.ac.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nashida
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Sato
authors.forename: Maiko
authors.initials: M
authors.lastname: Haga-Tsujimura
authors.forename: Sumio
authors.initials: S
authors.lastname: Yoshie
authors.forename: Ken
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Akane
authors.initials: A
authors.lastname: Imai
authors.forename: Hiromi
authors.initials: H
authors.lastname: Shimomura
mesh_terms: D061354:Acinar Cells / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000938:Antigen-Presenting Cells / Q000378:metabolism*; D015891:Cystatins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D007684:Kidney Tubules / Q000166:cytology; D008297:Male; D010306:Parotid Gland / Q000166:cytology*; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015891:Cystatins; C579140:cystatin D, rat