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Cell Adh Migr. 2018 May 4;12(3):185-194. doi: 10.1080/19336918.2017.1377388. Epub 2017 Nov 6.

Calpain2 mediates Rab5-driven focal adhesion disassembly and cell migration.

Author information

1
a Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile , Santiago , Chile.
2
b Molecular Pathology Laboratory , Institute of Biochemistry and Microbiology, Sciences Faculty, Universidad Austral de Chile , Valdivia , Chile.
3
c Faculty of Health Sciences, Universidad Central de Chile , Santiago , Chile.
4
d Advanced Center for Chronic Diseases (ACCDiS) , Universidad de Chile , Santiago , Chile.
5
e Programa de Biología Celular y Molecular , Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile , Santiago , Chile.
6
f Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD) , Universidad de Chile , Santiago , Chile.

Abstract

The early endosome protein Rab5 was recently shown to promote cell migration by enhancing focal adhesion disassembly through mechanisms that remain elusive. Focal adhesion disassembly is associated to proteolysis of talin, in a process that requires calpain2. Since calpain2 has been found at vesicles and endosomal compartments, we hypothesized that Rab5 stimulates calpain2 activity, leading to enhanced focal adhesion disassembly in migrating cells. We observed that calpain2 co-localizes with EEA1-positive early endosomes and co-immunoprecipitates with EEA1 and Rab5 in A549 lung carcinoma cells undergoing spreading, whereas Rab5 knock-down decreased the accumulation of calpain2 at early endosomal-enriched fractions. In addition, Rab5 silencing decreased calpain2 activity, as shown by cleavage of the fluorogenic substrate tBOC-LM-CMAC and the endogenous substrate talin. Accordingly, Rab5 promoted focal adhesion disassembly in a calpain2-dependent manner, as expression of GFP-Rab5 accelerated focal adhesion disassembly in nocodazole-synchronized cells, whereas pharmacological inhibition of calpain2 with N-acetyl-Leu-Leu-Met prevented both focal adhesion disassembly and cell migration induced by Rab5. In summary, these data uncover Rab5 as a novel regulator of calpain2 activity and focal adhesion proteolysis leading to cell migration.

KEYWORDS:

Rab5; calpain2; early endosome; focal adhesion; proteolysis

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