Journal article
Rab27b regulates exocytosis of secretory vesicles in acinar epithelial cells from the lacrimal gland
American Journal of Physiology: Cell Physiology, Vol.301(2), pp.C507-C521
08/01/2011
DOI: 10.1152/ajpcell.00355.2010
PMCID: PMC3154548
PMID: 21525430
Abstract
Tear proteins are supplied by the regulated fusion of secretory vesicles at the apical surface of lacrimal gland acinar cells, utilizing trafficking mechanisms largely yet uncharacterized. We investigated the role of Rab27b in the terminal release of these secretory vesicles. Confocal fluorescence microscopy analysis of primary cultured rabbit lacrimal gland acinar cells revealed that Rab27b was enriched on the membrane of large subapical vesicles that were significantly colocalized with Rab3D and Myosin 5C. Stimulation of cultured acinar cells with the secretagogue carbachol resulted in apical fusion of these secretory vesicles with the plasma membrane. Evaluation of morphological changes by transmission electron microscopy of lacrimal glands from
Rab27b
−/−
and
Rab27
ash/ash
/Rab27b
−/−
mice, but not
ashen
mice deficient in Rab27a, showed changes in abundance and organization of secretory vesicles, further confirming a role for this protein in secretory vesicle exocytosis. Glands lacking Rab27b also showed increased lysosomes, damaged mitochondria, and autophagosome-like organelles. In vitro, expression of constitutively active Rab27b increased the average size but retained the subapical distribution of Rab27b-enriched secretory vesicles, whereas dominant-negative Rab27b redistributed this protein from membrane to the cytoplasm. Functional studies measuring release of a cotransduced secretory protein, syncollin-GFP, showed that constitutively active Rab27b enhanced, whereas dominant-negative Rab27b suppressed, stimulated release. Disruption of actin filaments inhibited vesicle fusion to the apical membrane but did not disrupt homotypic fusion. These data show that Rab27b participates in aspects of lacrimal gland acinar cell secretory vesicle formation and release.
Details
- Title: Subtitle
- Rab27b regulates exocytosis of secretory vesicles in acinar epithelial cells from the lacrimal gland
- Creators
- Lilian Chiang - Schools of PharmacyJulie Ngo - Schools of PharmacyJoel E. Schechter - Institute of Cell Biology and NeurobiologySerhan Karvar - University of Southern CaliforniaTanya Tolmachova - Imperial College LondonMiguel C. Seabra - Imperial College LondonAlistair N. Hume - University of NottinghamSarah F. Hamm-Alvarez - Schools of Pharmacy, Cell and Neurobiology, and
- Resource Type
- Journal article
- Publication Details
- American Journal of Physiology: Cell Physiology, Vol.301(2), pp.C507-C521
- Publisher
- American Physiological Society
- DOI
- 10.1152/ajpcell.00355.2010
- PMID
- 21525430
- PMCID
- PMC3154548
- ISSN
- 0363-6143
- eISSN
- 1522-1563
- Grant note
- National Institutes of Health
- Language
- English
- Date published
- 08/01/2011
- Academic Unit
- Internal Medicine
- Record Identifier
- 9984695830002771
Metrics
3 Record Views