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Characterization of VAMP‐2 in the lung: implication in lung surfactant secretion
Author(s) -
Wang Pengcheng,
Howard Marcia D.,
Zhang Honghao,
Chintagari Narendranath Reddy,
Bell Anna,
Jin Nili,
Mishra Amarjit,
Liu Lin
Publication year - 2012
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1042/cbi20110146
Subject(s) - lamellar granule , secretion , pulmonary surfactant , microbiology and biotechnology , vesicle , chemistry , cytoplasm , surfactant protein d , fusion protein , receptor , biochemistry , biology , membrane , recombinant dna , gene , innate immune system
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.