Characterization of VAMP-2 in the lung: implication in lung surfactant secretion

Authors

  • Pengcheng Wang,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
    2. Department of Microbiology and Immunology, Medical College of Jinan University, Guangdong Province, Guangzhou 510632, People's Republic of China
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  • Marcia D. Howard,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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  • Honghao Zhang,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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  • Narendranath Reddy Chintagari,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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  • Anna Bell,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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  • Nili Jin,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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  • Amarjit Mishra,

    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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  • Lin Liu

    Corresponding author
    1. Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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To whom correspondence should be addressed (email lin.liu@okstate.edu).

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.

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