Journal
JOURNAL OF CELL SCIENCE
Volume 133, Issue 22, Pages -Publisher
COMPANY BIOLOGISTS LTD
DOI: 10.1242/jcs.244830
Keywords
PAR3; PAR-3; ASPP2; aPKC; Epithelium; Polarity
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Funding
- Ministry of Education, Culture, Sports, Science and Technology of Japan
- Japan Society for the Promotion of Science (JSPS) KAKENHI [JP23112003, JP13670129, JP17K17991]
- Yokohama Foundation for Advancement of Medical Science
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Cell polarity is essential for various asymmetric cellular events, and the partitioning defective (PAR) protein PAR3 (encoded by PARD3 in mammals) plays a unique role as a cellular landmark to establish polarity. In epithelial cells, PAR3 localizes at the subapical border, such as the tight junction in vertebrates, and functions as an apical determinant. Although we know a great deal about the regulators of PAR3 localization, how PAR3 is concentrated and localized to a specific membrane domain remains an important question to be clarified. In this study, we demonstrate that ASPP2 (also known as TP53BP2), which controls PAR3 localization, links PAR3 and protein phosphatase 1 (PP1). The ASPP2-PP1 complex dephosphorylates a novel phosphorylation site, Ser852, of PAR3. Furthermore, Ser852- or Ser889-unphosphorylatable PAR3 mutants form protein clusters, and ectopically localize to the lateral membrane. Concomitance of clustering and ectopic localization suggests that PAR3 localization is a consequence of local clustering. We also demonstrate that unphosphorylatable forms of PAR3 exhibited a low molecular turnover and failed to coordinate rapid reconstruction of the tight junction, supporting that both the phosphorylated and dephosphorylated states are essential for the functional integrity of PAR3.
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