title: Numb controls E-cadherin endocytosis through p120 catenin with aPKC.
abstract: Cadherin trafficking controls tissue morphogenesis and cell polarity. The endocytic adaptor Numb participates in apicobasal polarity by acting on intercellular adhesions in epithelial cells. However, it remains largely unknown how Numb controls cadherin-based adhesion. Here, we found that Numb directly interacted with p120 catenin (p120), which is known to interact with E-cadherin and prevent its internalization. Numb accumulated at intercellular adhesion sites and the apical membrane in epithelial cells. Depletion of Numb impaired E-cadherin internalization, whereas depletion of p120 accelerated internalization. Expression of the Numb-binding fragment of p120 inhibited E-cadherin internalization in a dominant-negative fashion, indicating that Numb interacts with the E-cadherin/p120 complex and promotes E-cadherin endocytosis. Impairment of Numb induced mislocalization of E-cadherin from the lateral membrane to the apical membrane. Atypical protein kinase C (aPKC), a member of the PAR complex, phosphorylated Numb and inhibited its association with p120 and α-adaptin. Depletion or inhibition of aPKC accelerated E-cadherin internalization. Wild-type Numb restored E-cadherin internalization in the Numb-depleted cells, whereas a phosphomimetic mutant or a mutant with defective α-adaptin-binding ability did not restore the internalization. Thus, we propose that aPKC phosphorylates Numb to prevent its binding to p120 and α-adaptin, thereby attenuating E-cadherin endocytosis to maintain apicobasal polarity.
authors.affiliation: Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Showa, Nagoya, Aichi 466-8550, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Sato
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Shujie
authors.initials: S
authors.lastname: Wang
authors.forename: Mai
authors.initials: M
authors.lastname: Kakeno
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuzawa
authors.forename: Toshinori
authors.initials: T
authors.lastname: Matsui
authors.forename: Keiko
authors.initials: K
authors.lastname: Yokoi
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Murase
authors.forename: Ikuko
authors.initials: I
authors.lastname: Sugiyama
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ozawa
authors.forename: Kozo
authors.initials: K
authors.lastname: Kaibuchi
mesh_terms: D033965:Adaptor Protein Complex alpha Subunits / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D051177:Catenins / Q000378:metabolism*; D002448:Cell Adhesion; D002460:Cell Line; D016764:Cell Polarity; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D004285:Dogs; D004705:Endocytosis; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D034622:RNA Interference; D000095002:Delta Catenin
chemical_list: D033965:Adaptor Protein Complex alpha Subunits; D015820:Cadherins; D051177:Catenins; D002966:Clathrin; C493410:FABP4 protein, human; D050556:Fatty Acid-Binding Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C113026:NUMB protein, human; C115015:PKC-3 protein; D011493:Protein Kinase C; D000095002:Delta Catenin