title: LC3-dependent intracellular membrane tubules induced by gamma-protocadherins A3 and B2: a role for intraluminal interactions.
abstract: Clustered protocadherins (Pcdhs) are a family of cadherin-like molecules arranged in gene clusters (alpha, beta, and gamma). gamma-Protocadherins (Pcdh-gammas) are involved in cell-cell interactions, but their prominent intracellular distribution in vivo and different knock-out phenotypes suggest that these molecules participate in still unidentified processes. We found using correlative light and electron microscopy that Pcdh-gammaA3 and -gammaB2, but not -gammaC4, -alpha1, or N-cadherin, generate intracellular juxtanuclear membrane tubules when expressed in cells. These tubules recruit the autophagy marker MAP1A/1B LC3 (LC3) but are not associated with autophagic vesicles. Lipidation of LC3 is required for its coclustering with Pcdh-gamma tubules, suggesting the involvement of an autophagic-like molecular cascade. Expression of wild-type LC3 with Pcdh-gammaA3 increased tubule length whereas expression of lipidation-defective LC3 decreased tubule length relative to Pcdh-gammaA3 expressed alone. The tubules were found to emanate from lysosomes. Deletion of the luminal/extracellular domain of Pcdh-gammaA3 preserved lysosomal targeting but eliminated tubule formation whereas cytoplasmic deletion eliminated both lysosomal targeting and tubule formation. Deletion of the membrane-proximal three cadherin repeats resulted in tubes that were narrower than those produced by full-length molecules. These results suggest that Pcdh-gammaA and -gammaB families can influence the shape of intracellular membranes by mediating intraluminal interactions within organelles.
authors.affiliation: Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: Hugo H
authors.initials: HH
authors.lastname: Hanson
authors.forename: Semie
authors.initials: S
authors.lastname: Kang
authors.forename: Mónica
authors.initials: M
authors.lastname: Fernández-Monreal
authors.forename: Twethida
authors.initials: T
authors.lastname: Oung
authors.forename: Murat
authors.initials: M
authors.lastname: Yildirim
authors.forename: Rebecca
authors.initials: R
authors.lastname: Lee
authors.forename: Kimita
authors.initials: K
authors.lastname: Suyama
authors.forename: Rachel B
authors.initials: RB
authors.lastname: Hazan
authors.forename: Greg R
authors.initials: GR
authors.lastname: Phillips
mesh_terms: D000818:Animals; D000070585:Cadherin Related Proteins; D015820:Cadherins / Q000235:genetics / Q000502:physiology*; D002450:Cell Communication; D002460:Cell Line; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007668:Kidney / Q000196:embryology; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D008870:Microtubules / Q000648:ultrastructure; D010957:Plasmids; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D000070585:Cadherin Related Proteins; D015820:Cadherins; C464785:Gamma-protocadherins; D008164:Luminescent Proteins; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; C000608359:PCDH-GAMMA-A3, human; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins