APP and Bace1: Differential effect of cholesterol enrichment on processing and plasma membrane mobility
Claudia Capitini,
Alessandra Bigi,
Niccolò Parenti,
Marco Emanuele,
Niccolò Bianchi,
Roberta Cascella,
Cristina Cecchi,
Laura Maggi,
Francesco Annunziato,
Francesco Saverio Pavone,
Martino Calamai
Affiliations
Claudia Capitini
Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, 50019 Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, 50019Florence, Italy
Alessandra Bigi
Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
Niccolò Parenti
European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, 50019Florence, Italy
Marco Emanuele
European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, 50019Florence, Italy
Niccolò Bianchi
European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, 50019Florence, Italy
Roberta Cascella
Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
Cristina Cecchi
Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
Laura Maggi
Department of Experimental and Clinical Medicine, University of Florence 50134 Florence, Italy
Francesco Annunziato
Department of Experimental and Clinical Medicine, University of Florence 50134 Florence, Italy
Francesco Saverio Pavone
Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, 50019 Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, 50019Florence, Italy; National Institute of Optics, National Research Council of Italy (CNR), Largo Fermi 6, 50125Florence, Italy
Martino Calamai
European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, 50019Florence, Italy; National Institute of Optics, National Research Council of Italy (CNR), Largo Fermi 6, 50125Florence, Italy; Corresponding author
Summary: High cholesterol levels are a risk factor for the development of Alzheimer’s disease. Experiments investigating the influence of cholesterol on the proteolytic processing of the amyloid precursor protein (APP) by the β-secretase Bace1 and on their proximity in cells have led to conflicting results. By using a fluorescence bioassay coupled with flow cytometry we found a direct correlation between the increase in membrane cholesterol amount and the degree of APP shedding in living human neuroblastoma cells. Analogue results were obtained for cells overexpressing an APP mutant that cannot be processed by α-secretase, highlighting the major influence of cholesterol enrichment on the cleavage of APP carried out by Bace1. By contrast, the cholesterol content was not correlated with changes in membrane dynamics of APP and Bace1 analyzed with single molecule tracking, indicating that the effect of cholesterol enrichment on APP processing by Bace1 is uncoupled from changes in their lateral diffusion.
