Cell-mediated extracellular acidification and bone resorption: evidence for a low pH in resorbing lacunae and localization of a 100-kD lysosomal membrane protein at the osteoclast ruffled border.
Year: 1985
Type: article
Abstract: The extracellular compartment where bone resorption occurs, between the osteoclast and bone matrix, is shown in this report to be actively acidified. The weak base acridine orange accumulates within this compartment but dissipates after incubation with ammonium chloride. Upon removal of ammonium chloride, the cells are able to rapidly reacidify this compartment. The highly convoluted plasma membrane of the osteoclast facing this acidic compartment (ruffled border) is shown to contain a 100-kD integral membrane protein otherwise present in limiting membranes of lysosomes and other related acidified organelles (Reggio, H., D. Bainton, E. Harms, E. Coudrier, and D. Louvard, 1984, J. Cell Biol., 99:1511-1526; Tougard, C., D. Louvard, R. Picart, and A. Tixier-Vidal, 1985, J. Cell Biol. 100:786-793). Antibodies recognizing this 100-kD lysosomal membrane protein cross-react with a proton-pump ATPase from pig gastric mucosae (Reggio, H., D. Bainton, E. Harms, E. Coudrier, and D. Louvard, 1984, J. Cell Biol., 99:1511-1526), therefore raising the possibility that it plays a role in the acidification of both intracellular organelles and extracellular compartments. Lysosomal enzymes are also directionally secreted by the osteoclast into the acidified extracellular compartment which can therefore be considered as the functional equivalent of a secondary lysosome with a low pH, acid hydrolases, the substrate, and a limiting membrane containing the 100-kD antigen.
Source: The Journal of Cell Biology
Authors: R Baron, L Neff, D Louvard, P J Courtoy
Language: English
Topic: Bone Metabolism and Diseases
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Award: G1781284550
OpenAlex ID: W2075356469