APStracts 2:0384C, 1995.

Osteoclasts express the b2 isoform of the vacuolar h+-atpase intracellularly and on their plasma membranes. Lee, Beth S., L. Shannon Holliday, Bisola Ojikutu, Irina Krits, and Stephen L. Gluck. Departments of Medicine and Cell Biology and Physiology, and the George M. O'Brien Center for Kidney and Urologic Diseases, Washington University School of Medicine, St. Louis, Missouri 63110

APStracts 2:0384C, 1995.

Osteoclasts express high levels of vacuolar H+-ATPase (V-ATPase) in their ruffled membrane, driving the secretion of protons required for normal bone resorption. Previous reports have suggested that the B subunit of the osteoclast V-ATPase differs from those expressed in kidney and other tissues. In this study, B subunit isoform-specific antibodies and cDNA probes were used to examine which B subunit isoform is expressed in osteoclasts and osteoclast-like cells. Immunoblot and RNA hybridization analysis were used to demonstrate that cells from an osteoclast-rich mouse bone marrow culture model express the B2, but not the B1 subunit isoform. Immuno cytochemical staining of murine osteoclasts generated in vitro and of native rat osteoclasts in bone sections showed that the B2, but not the B1 isoform, was expressed at high levels and was polarized to the ruffled membrane. Human marrow cultures and monocyte-derived macrophages, used as models for osteoclasts, also expressed the B2 but not the B1 subunit isoform. These results indicate that V-ATPases containing the B2 subunit isoform mediate osteoclast bone resorption.

Received 8 August 1995; accepted in final form 17 October 1995.
APS Manuscript Number C489-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95