title: Differential regulation of adherens junction dynamics during apical-basal polarization.
abstract: Adherens junctions (AJs) in epithelial cells are constantly turning over to modulate adhesion properties under various physiological and developmental contexts, but how such AJ dynamics are regulated during the apical-basal polarization of primary epithelia remains unclear. Here, we used new and genetically validated GFP markers of Drosophila E-cadherin (DE-cadherin, hereafter referred to as DE-Cad) and β-catenin (Armadillo, Arm) to quantitatively assay the in vivo dynamics of biosynthetic turnover and membrane redistribution by fluorescence recovery after photobleaching (FRAP) assays. Our data showed that membrane DE-Cad and Arm in AJs of polarizing epithelial cells had much faster biosynthetic turnover than in polarized cells. Fast biosynthetic turnover of membrane DE-Cad is independent of actin- and dynamin-based trafficking, but is microtubule-dependent. Furthermore, Arm in AJs of polarizing cells showed a faster and diffusion-based membrane redistribution that was both quantitatively and qualitatively different from the slower and exchange-based DE-Cad membrane distribution, indicating that the association of Arm with DE-Cad is more dynamic in polarizing cells, and only becomes stable in polarized epithelial cells. Consistently, biochemical assays showed that the binding of Arm to DE-Cad is weaker in polarizing cells than in polarized cells. Our data revealed that the molecular interaction between DE-Cad and Arm is modulated during apical-basal polarization, suggesting a new mechanism that might be crucial for establishing apical-basal polarity through regulating the AJ dynamics.
authors.affiliation: Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, 3500 Terrace Street, Pittsburgh, PA 15261,  USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Huang
authors.forename: Lynn
authors.initials: L
authors.lastname: Huang
authors.forename: Yi-Jiun
authors.initials: YJ
authors.lastname: Chen
authors.forename: Erin
authors.initials: E
authors.lastname: Austin
authors.forename: Caitlin E
authors.initials: CE
authors.lastname: Devor
authors.forename: Fabrice
authors.initials: F
authors.lastname: Roegiers
authors.forename: Yang
authors.initials: Y
authors.lastname: Hong
mesh_terms: D022005:Adherens Junctions / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D051186:Armadillo Domain Proteins / Q000737:chemistry*; D015820:Cadherins / Q000737:chemistry*; D016764:Cell Polarity; D004330:Drosophila / Q000737:chemistry / Q000235:genetics; D029721:Drosophila Proteins / Q000737:chemistry*; D004625:Embryo, Nonmammalian / Q000737:chemistry / Q000502:physiology; D004847:Epithelial Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D036681:Fluorescence Recovery After Photobleaching; D049452:Green Fluorescent Proteins / Q000737:chemistry; D047468:Immunoprecipitation; D008566:Membranes / Q000737:chemistry / Q000502:physiology; D046912:Multiprotein Complexes / Q000737:chemistry; D011485:Protein Binding; D055550:Protein Stability; D021381:Protein Transport; D014157:Transcription Factors / Q000737:chemistry*
chemical_list: C495305:ARM protein, Drosophila; D051186:Armadillo Domain Proteins; D015820:Cadherins; D029721:Drosophila Proteins; D046912:Multiprotein Complexes; D014157:Transcription Factors; C501889:shg protein, Drosophila; D049452:Green Fluorescent Proteins