title: Postnatal expression of sialin in the mouse submandibular gland.
abstract: OBJECTIVE
  Sialin has been identified as a sialic acid and aspartate/glutamate transporter. Both cytoplasmic localization and the plasma membrane labelling pattern suggested that sialin may possess multiple transport functions in different cell types. In mouse embryos, sialin expression was primarily detected in the central nervous system. However, sialin shows widespread and high-level expression in adult tissues. Despite its ubiquitous expression and important functions, the postnatal expression profile and subcellular localization of sialin in the salivary gland remains elusive. The aim of the present study was to investigate the expression and subcellular distribution of sialin during postnatal development in the mouse submandibular gland (SMG).
  
  
  METHODS
  Six SMGs from both female and male C57BL/6 mice were collected at P10, P30 and P90, and the material from each littermate of either sex was pooled to extract total RNA and tissue protein. The remaining tissues were immediately fixed in 10% neutral buffered formalin for histological analysis. The mRNA and protein expression levels of sialin were examined by quantitative real-time RT-PCR and Western blot analysis. The subcellular distribution of sialin was analysed by immunohistochemistry and immunofluorescence.
  
  
  RESULTS
  The postnatal expression level of sialin in the mouse SMG was comparable with that in brain at each time point tested. The temporal expression of sialin in the SMG gradually increased during postnatal maturation. Immunohistochemical and immunofluorescence analysis demonstrated that sialin was predominantly expressed on the basal cytoplasmic membrane of acini and ducts, as well as in some myoepithelial cells in the SMG.
  
  
  CONCLUSIONS
  The high-level expression and subcellular distribution pattern of sialin in the SMG suggest that sialin may play an important role in the transport and secretion of saliva.
authors.affiliation: Salivary Gland Disease Center and Molecular Laboratory for Gene Therapy & Tooth Regeneration, Capital Medical University School of Stomatology, Tian Tan Xi Li No.4, Beijing 100050, China.
authors.forename: Miao
authors.initials: M
authors.lastname: He
authors.forename: Fuyu
authors.initials: F
authors.lastname: Lin
authors.forename: Lizheng
authors.initials: L
authors.lastname: Qin
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Guan
authors.initials: G
authors.lastname: Yang
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.forename: Songlin
authors.initials: S
authors.lastname: Wang
mesh_terms: D061354:Acinar Cells / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001485:Basement Membrane / Q000737:chemistry / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D027361:Organic Anion Transporters / Q000096:biosynthesis*; D060888:Real-Time Polymerase Chain Reaction; D013363:Submandibular Gland / Q000737:chemistry / Q000378:metabolism*; D027981:Symporters / Q000096:biosynthesis*; D014018:Tissue Distribution
chemical_list: D027361:Organic Anion Transporters; D027981:Symporters; C421224:sialic acid transport proteins