Surfactant secretion in LRRK2 knock-out rats : changes in lamellar body morphology and rate of exocytosis

Miklavc, P; Ehinger, K; Thompson, KE; Hobi, N; Shimshek, DR; Frick, M

Abstract

Leucine-rich repeat kinase 2 (LRRK2) is known to play a role in the pathogenesis of various diseases including Parkinson disease, morbus Crohn, leprosy and cancer. LRRK2 is suggested to be involved in a number of cell biological processes such as vesicular trafficking, transcription, autophagy and lysosomal pathways. Recent histological studies of lungs of LRRK2 knock-out (LRRK2 -/-) mice revealed significantly enlarged lamellar bodies (LBs) in alveolar type II (ATII) epithelial cells. LBs are large, lysosome-related storage organelles for pulmonary surfactant, which is released into the alveolar lumen upon LB exocytosis. In this study we used high-resolution, subcellular live-cell imaging assays to investigate whether similar morphological changes can be observed in primary ATII cells from LRRK2 -/- rats and whether such changes result in altered LB exocytosis. Similarly to the report in mice, ATII cells from LRRK2 -/- rats contained significantly enlarged LBs resulting in a >50% increase in LB volume. Stimulation of ATII cells with ATP elicited LB exocytosis in a significantly increased proportion of cells from LRRK2 -/- animals. LRRK2 -/- cells also displayed increased intracellular Ca2+ release upon ATP treatment and significant triggering of LB exocytosis. These findings are in line with the strong Ca2+-dependence of LB fusion activity and suggest that LRRK2 -/- affects exocytic response in ATII cells via modulating intracellular Ca2+ signaling. Post-fusion regulation of surfactant secretion was unaltered. Actin coating of fused vesicles and subsequent vesicle compression to promote surfactant expulsion were comparable in cells from LRRK2 -/- and wt animals. Surprisingly, surfactant (phospholipid) release from LRRK2 -/- cells was reduced following stimulation of LB exocytosis possibly due to impaired LB maturation and surfactant loading of LBs. In summary our results suggest that LRRK2 -/- affects LB size, modulates intracellular Ca2+ signaling and promotes LB exocytosis upon stimulation of ATII cells with ATP.

Citation

Miklavc, P., Ehinger, K., Thompson, K., Hobi, N., Shimshek, D., & Frick, M. (2014). Surfactant secretion in LRRK2 knock-out rats : changes in lamellar body morphology and rate of exocytosis. PLoS ONE, 9(1), e84926. https://doi.org/10.1371/journal.pone.0084926

• Journal Article Type: Article
• Acceptance Date: Nov 19, 2013
• Online Publication Date: Jan 21, 2014
• Publication Date: Jan 21, 2014
• Deposit Date: Oct 24, 2016
• Publicly Available Date: Oct 24, 2016
• Journal: PLoS ONE
• Electronic ISSN: 1932-6203
• Publisher: Public Library of Science
• Volume: 9
• Issue: 1
• Pages: e84926
• DOI: https://doi.org/10.1371/journal.pone.0084926
• Publisher URL: http://dx.doi.org/10.1371/journal.pone.0084926
• Related Public URLs: http://journals.plos.org/plosone/
• Additional Information: Funders : BiU grant D.5006;DFG grant D-1402/3-1;Ministry of Science, Research and the Arts Baden-Wuerttemberg