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Arch Biochem Biophys. 2014 Mar 1;545:83-91. doi: 10.1016/j.abb.2014.01.006. Epub 2014 Jan 15.

CK2 involvement in ESCRT-III complex phosphorylation.

Author information

  • 1Department of Biomedical Sciences, University of Padova, V.le G. Colombo 3, Padova, Italy. Electronic address: mauro.salvi@unipd.it.
  • 2Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, Montebello, Norway.
  • 3Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA.
  • 4Department of Biomedical Sciences, University of Padova, V.le G. Colombo 3, Padova, Italy; CNR Institute of Neurosciences, V.le G. Colombo 3, Padova, Italy; Venetian Institute for Molecular Medicine (VIMM), via Orus 2, 35129 Padova, Italy.

Abstract

The multivesicular body (MVB) sorting pathway is a mechanism for delivering transmembrane proteins into the lumen of the lysosome for degradation. ESCRT-III is the final complex in the pathway that assembles on endosomes and executes membrane scission of intraluminal vesicles. In addition, proteins of this complex are involved in other topologically similar processes such as cytokinesis, virus egress and autophagy. Here we show that protein kinase CK2α is involved in the phosphorylation of the ESCRT-III subunits CHMP3 and CHMP2B, as well as of VPS4B/SKD1, an ATPase that mediates ESCRT-III disassembly. This phosphorylation is observed both in vitro and in cells. While we do not observe recruitment of CK2α to endosomes, we demonstrate the localization of CK2α to midbodies during cytokinesis. Phosphomimetic and non-phosphorylatable mutants of ESCRT-III proteins can still bind endosomes and localize to midbodies, indicating that CK2α does not regulate ESCRT-III localization. Finally, we analyzed two cellular functions where CHMP3, CHMP2B and VPS4 are known to be involved, epidermal growth factor degradation and cytokinetic abscission. We demonstrate that the former is impaired by CK2α downregulation whereas the latter is not affected. Taken together, our results indicate that CK2α regulates the function of ESCRT-III proteins in MVB sorting.

Copyright © 2014 Elsevier Inc. All rights reserved.

KEYWORDS:

CHMP2B; CHMP3; ESCRT; Protein kinase CK2; VPS4

PMID:
24440309
[PubMed - indexed for MEDLINE]
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