Antibody-induced acetylcholine receptor clusters inhabit liquid-ordered and liquid-disordered domains

• Autores: Kamerbeek, Constanza B.; Borroni, María Virginia; Pediconi, María F.; Sato, Satoshi B.; Kobayashi, Toshihide; Barrantes, Francisco José
• Año de publicación: 2013
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Biophysical Journal Vol. 105, N° 7, 2013
• Materia: MEDICINA; RECEPTORES; MEMBRANAS CELULARES; COLESTEROL; ANTICUERPOS
• Institución: Pontificia Universidad Católica Argentina

Fil: Kamerbeek, Constanza B. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina
Fil: Borroni, María Virginia. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina
Fil: Pediconi, María F. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina
Fil: Sato, Satoshi B. Lipid Biology Laboratory, RIKEN; Japón
Fil: Kobayashi, Toshihide. Lipid Biology Laboratory, RIKEN; Japón
Fil: Barrantes, Francisco José. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Neurobiología Molecular; Argentina
Fil: Barrantes Francisco José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Barrantes, Francisco José. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina
Abstract: The distribution of nicotinic acetylcholine receptor (AChR) clusters at the cell membrane was studied in CHO-K1/A5 cells using fluorescence microscopy. Di-4-ANEPPDHQ, a fluorescent probe that differentiates between liquid-ordered (Lo) and liquid-disordered (Ld) phases in model membranes, was used in combination with monoclonal anti-AChR antibody labeling of live cells, which induces AChR clustering. The so-called generalized polarization (GP) of di-4-ANEPPDHQ was measured in regions of the cell-surface membrane associated with or devoid of antibody-induced AChR clusters, respectively. AChR clusters were almost equally distributed between Lo and Ld domains, independently of receptor surface levels and agonist (carbamoylcholine and nicotine) or antagonist (α-bungarotoxin) binding. Cholesterol depletion diminished the cell membrane mean di-4-ANEPPDHQ GP and the number of AChR clusters associated with Ld membrane domains increased concomitantly. Depolymerization of the filamentous actin cytoskeleton by Latrunculin A had the opposite effect, with more AChR clusters associated with Lo domains. AChR internalized via small vesicles having lower GP and lower cholesterol content than the surface membrane. Upon cholesterol depletion, only 12% of the AChR-containing vesicles costained with the fluorescent cholesterol analog fPEG-cholesterol, i.e., AChR endocytosis was essentially dissociated from that of cholesterol. In conclusion, the distribution of AChR submicron-sized clusters at the cell membrane appears to be regulated by cholesterol content and cytoskeleton integrity.