Local phosphocycling mediated by LOK/SLK restricts ezrin function to the apical aspect of epithelial cells

In this paper, we describe how a dynamic regulatory process is necessary to restrict microvilli to the apical aspect of polarized epithelial cells. We found that local phosphocycling regulation of ezrin, a critical plasma membrane-cytoskeletal linker of microvilli, was required to restrict its funct...

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Bibliographic Details
Published in:The Journal of cell biology 2012-12, Vol.199 (6), p.969-984
Main Authors: Viswanatha, Raghuvir, Ohouo, Patrice Y, Smolka, Marcus B, Bretscher, Anthony
Format: Article
Language:English
Subjects:
Cell Line
Cell Polarity - genetics
Cell Polarity - physiology
Cytoskeletal Proteins - metabolism
Enzyme Inhibitors - pharmacology
Epithelial Cells - metabolism
Gene Silencing
Humans
Microvilli - drug effects
Microvilli - enzymology
Phosphorylation
Protein-Serine-Threonine Kinases - antagonists & inhibitors
Protein-Serine-Threonine Kinases - genetics
Protein-Serine-Threonine Kinases - metabolism
Proteomics
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Summary:In this paper, we describe how a dynamic regulatory process is necessary to restrict microvilli to the apical aspect of polarized epithelial cells. We found that local phosphocycling regulation of ezrin, a critical plasma membrane-cytoskeletal linker of microvilli, was required to restrict its function to the apical membrane. Proteomic approaches and ribonucleic acid interference knockdown identified lymphocyte-oriented kinase (LOK) and SLK as the relevant kinases. Using drug-resistant LOK and SLK variants showed that these kinases were sufficient to restrict ezrin function to the apical domain. Both kinases were enriched in microvilli and locally activated there. Unregulated kinase activity caused ezrin mislocalization toward the basolateral domain, whereas expression of the kinase regulatory regions of LOK or SLK resulted in local inhibition of ezrin phosphorylation by the endogenous kinases. Thus, the domain-specific presence of microvilli is a dynamic process requiring a localized kinase driving the phosphocycling of ezrin to continually bias its function to the apical membrane.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.201207047