Mm. Bartl et al., Multiple receptors mediate apoJ-dependent clearance of cellular debris into nonprofessional phagocytes, EXP CELL RE, 271(1), 2001, pp. 130-141
Phagocytosis of apoptotic, senescent, and dying cells by macrophages is a w
ell characterized process. More recently it has been shown that in addition
to macrophages vital neighboring cells in the affected tissue participate
in the cellular clearance. While scavenger receptors have been shown to med
iate uptake into macrophages, it is poorly understood how cellular debris i
s internalized by nonprofessional phagocytes. We here analyze the endocytic
activity of vital fibroblasts and epithelial cells exposed to cellular deb
ris and membrane remnants. We show a mutual stimulation in the endocytosis
of debris and apolipoproteinJ (clusterin) in these cells. Experiments using
RAP (receptor-associated protein) to block ligand binding to LRP and megal
in as well as studies in LRP- and megalin-deficient cells suggest that the
uptake of apoJ and cellular debris is mediated by megalin, LRP, and yet uni
dentified internalization mechanisms. (C) 2001 Academic Press.