Actin depolymerisation and crosslinking join forces with myosin II to contract actin coats on fused secretory vesicles

Miklavc, P; Ehinger, K; Sultan, A; Felder, T; Paul, P; Gottschalk, KE; Frick, M

Abstract

In many secretory cells actin and myosin are specifically recruited to the surface of secretory granules following their fusion with the plasma membrane. Actomyosin-dependent compression of fused granules is essential to promote active extrusion of cargo. However, little is known about molecular mechanisms regulating actin coat formation and contraction. Here, we provide a detailed kinetic analysis of the molecules regulating actin coat contraction on fused lamellar bodies in primary alveolar type II cells. We demonstrate that ROCK1 and myosin light chain kinase 1 (MLCK1, also known as MYLK) translocate to fused lamellar bodies and activate myosin II on actin coats. However, myosin II activity is not sufficient for efficient actin coat contraction. In addition, cofilin-1 and α-actinin translocate to actin coats. ROCK1-dependent regulated actin depolymerisation by cofilin-1 in cooperation with actin crosslinking by α-actinin is essential for complete coat contraction. In summary, our data suggest a complementary role for regulated actin depolymerisation and crosslinking, and myosin II activity, to contract actin coats and drive secretion.

Citation

Miklavc, P., Ehinger, K., Sultan, A., Felder, T., Paul, P., Gottschalk, K., & Frick, M. (2015). Actin depolymerisation and crosslinking join forces with myosin II to contract actin coats on fused secretory vesicles. Journal of Cell Science, 128(6), 1193-1203. https://doi.org/10.1242/jcs.165571

• Journal Article Type: Article
• Acceptance Date: Jan 25, 2015
• Online Publication Date: Mar 15, 2015
• Publication Date: Mar 15, 2015
• Deposit Date: Oct 24, 2016
• Publicly Available Date: Oct 24, 2016
• Journal: Journal of Cell Science
• Print ISSN: 0021-9533
• Electronic ISSN: 1477-9137
• Publisher: Company of Biologists
• Volume: 128
• Issue: 6
• Pages: 1193-1203
• DOI: https://doi.org/10.1242/jcs.165571
• Publisher URL: http://dx.doi.org/10.1242/jcs.165571
• Additional Information: Funders : Ministry of Science, Research and the Arts Baden-Wuerttemberg;Deutsche Forschungsgemeinschaft