Journal of Glycobiology
Open Access

Clusterin/ApoJ: How glycosylation modulates the function of this apolipoprotein

Glycobiology World Congress

August 10-12, 2015 Philadelphia, USA

Claudia Koch-Brandt

Posters-Accepted Abstracts: J Glycobiol

Abstract :

Clusterin (CLU), also known as Apolipoprotein J (ApoJ) is a highly glycosylated extracellular chaperone. In humans it is
expressed in a broad spectrum of tissues and related to a plethora of pathophysiological processes such as M. Alzheimer,
atherosclerosis and cancer where the protein exerts a cytoprotective role. In its dominant form it is expressed as a secretory
protein (sCLU) which during maturation is N-glycosylated and cleaved intra-cellularly in to �?±- and a �?²-chain connected by
five symmetrical disulfide bonds. In early studies we examined the role of the carbohydrate moieties in the vectorial secretion
of ApoJ at the apical surface of polarized epithelial cells. If N-glycosylation is inhibited by tunicamycin treatment the protein
is secreted in equal amounts at both cell surfaces demonstrating that the carbohydrates are dispensible for the acquisition of
a transport competent conformation, however indicating a role of the carbohydrate moieties in the vectorial transport of this
protein. Recently, it has been demonstrated that besides the predominant sCLU, rare intracellular CLU forms are expressed
in stressed cells. Since these isoforms do not enter nor complete the secretory pathway, they display either no or only core
glycosylation and are not proteolytically processed. Due to their sparsity, these intracellular forms are functionally poorly
characterized. To evaluate the functions of these stress-induced intracellular forms, we first examined whether these isoforms
display chaperone activity then investigate the impact of glycosylation and proteolytic maturation on this activity.