title: Characterization of VAMP-2 in the lung: implication in lung surfactant secretion.
abstract: Lung surfactant is crucial for reducing the surface tension of alveolar space, thus preventing the alveoli from collapse. Lung surfactant is synthesized in alveolar epithelial type II cells and stored in lamellar bodies before being released via the fusion of lamellar bodies with the apical plasma membrane. SNAREs (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptors) play an essential role in membrane fusion. We have previously demonstrated the requirement of t-SNARE (target SNARE) proteins, syntaxin 2 and SNAP-23 (N-ethylmaleimide-sensitive factor-attachment protein 23), in regulated surfactant secretion. Here, we characterized the distribution of VAMPs (vesicle-associated membrane proteins) in rat lung and alveolar type II cells. VAMP-2, -3 and -8 are shown in type II cells at both mRNA and protein levels. VAMP-2 and -8 were enriched in LB (lamellar body) fraction. Immunochemistry studies indicated that VAMP-2 was co-localized with the LB marker protein, LB-180. Functionally, the cytoplasmic domain of VAMP-2, but not VAMP-8 inhibited surfactant secretion in type II cells. We suggest that VAMP-2 is the v-SNARE (vesicle SNARE) involved in regulated surfactant secretion.
authors.affiliation: Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Wang
authors.forename: Marcia D
authors.initials: MD
authors.lastname: Howard
authors.forename: Honghao
authors.initials: H
authors.lastname: Zhang
authors.forename: Narendranath Reddy
authors.initials: NR
authors.lastname: Chintagari
authors.forename: Anna
authors.initials: A
authors.lastname: Bell
authors.forename: Nili
authors.initials: N
authors.lastname: Jin
authors.forename: Amarjit
authors.initials: A
authors.lastname: Mishra
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008561:Membrane Fusion; D037661:Pulmonary Surfactant-Associated Proteins / Q000032:analysis / Q000378:metabolism*; D050683:R-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D050600:SNARE Proteins / Q000378:metabolism; D050988:Vesicle-Associated Membrane Protein 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D037661:Pulmonary Surfactant-Associated Proteins; D050683:R-SNARE Proteins; D012333:RNA, Messenger; D050600:SNARE Proteins; C494706:Vamp2 protein, rat; C491830:Vamp8 protein, rat; D050988:Vesicle-Associated Membrane Protein 2