Existence of exocytotic hemifusion intermediates with a lifetime of up to seconds in type II pneumocytes

Miklavc, P, Albrecht, S, Wittekindt, OH, Schullian, P, Haller, T and Dietl, P 2009, 'Existence of exocytotic hemifusion intermediates with a lifetime of up to seconds in type II pneumocytes' , Biochemical Journal, 424 (1) , pp. 7-14.

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Abstract

Exocytosis proceeds through prefusion stages such as hemifusion, but hemifusion is still an elusive intermediate of unknown duration. Using darkfield and fluorescence microscopy in ATII (alveolar type II) cells containing large secretory vesicles (LBs; lamellar bodies), we show that exocytotic fusion events were accompanied by a mostly biphasic SLID (scattered light intensity decrease) originating from the vesicle border. Correlation with the diffusional behaviour of fluorescence markers for either content or membrane mixing revealed that the onset of the fast second phase of SLID corresponded to fusion pore formation, which was followed by vesicle swelling. In contrast, a slow first phase of SLID preceded pore formation considerably but could still be accompanied by diffusion of farnesylated DsRed, an inner plasma membrane leaflet marker, or Nile Red. We conclude that hemifusion is an exocytotic intermediate that may last for several seconds. SLID is a new, non-invasive approach by which a prefusion phase, including hemifusion, can be continuously recorded and distinguished from fusion pore formation and postfusion vesicle swelling.

Item Type: Article
Schools: Schools > School of Environment and Life Sciences
Journal or Publication Title: Biochemical Journal
Publisher: Portland Press
ISSN: 0264-6021
Related URLs:
Funders: Fonds zur Foerderung der Wissenschaftlichen Forschung, Deutsche Forschungsgemeinschaft, 6th framework of the European Union, Pulmo-Net
Depositing User: P Miklavc
Date Deposited: 02 Nov 2016 09:50
Last Modified: 02 Nov 2016 09:50
URI: http://usir.salford.ac.uk/id/eprint/40265

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