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MRCKα is activated by caspase cleavage to assemble an apical actin ring for epithelial cell extrusion

Paolo Armando Gagliardi1,2, Desiana Somale3,2, Alberto Puliafito2

  • 1Department of Oncology, University of Torino, Turin, Italy paolo.gagliardi@izb.unibe.ch.

The Journal of Cell Biology
|November 23, 2017
PubMed

Insights

Apoptotic cells form an apical actin ring (EAAR) that drives their extrusion from epithelial tissues. This ring is assembled after caspase-mediated cleavage of myotonic dystrophy kinase-related CDC42-binding kinase-α (MRCKα).

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Epithelial extrusion of apoptotic cells involves complex cellular rearrangements.
  • The precise molecular links between apoptosis initiation and extrusion mechanisms remain unclear.

Purpose of the Study:

  • To characterize the apoptotic extrusion apical actin ring (EAAR) and its role in epithelial extrusion.
  • To elucidate the signaling pathway connecting apoptosis to EAAR assembly and cell removal.

Main Methods:

  • Characterization of the EAAR structure and dynamics.
  • Analysis of F-actin flow, myosin contraction, and actin polymerization.
  • Investigating the role of caspase-mediated cleavage of myotonic dystrophy kinase-related CDC42-binding kinase-α (MRCKα).

Main Results:

  • Identified and characterized the EAAR, an actin ring assembled within the apoptotic cell.
  • Demonstrated that caspase-mediated cleavage of MRCKα triggers EAAR assembly.
  • Showcased EAAR's function in compacting and removing the apoptotic cell body through actomyosin dynamics.

Conclusions:

  • Established a causal link between apoptosis, MRCKα activation, and actomyosin cytoskeleton rearrangement during epithelial extrusion.
  • The EAAR is a key structure driven by MRCKα cleavage products for efficient cell removal.
  • Provides novel insights into the regulation of epithelial homeostasis and cell death.

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