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Protein kinase C–delta deficiency perturbs bone homeostasis by selective uncoupling of cathepsin K secretion and ruffled border formation in osteoclasts
Author(s) -
Cremasco Viviana,
Decker Corinne E,
Stumpo Deborah,
Blackshear Perry J,
Nakayama Keiichi I,
Nakayama Keiko,
Lupu Traian S,
Graham Daniel B,
Novack Deborah V,
Faccio Roberta
Publication year - 2012
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.1701
Subject(s) - secretion , homeostasis , microbiology and biotechnology , cathepsin , cathepsin k , protein kinase a , cathepsin d , chemistry , medicine , endocrinology , kinase , biology , osteoclast , enzyme , biochemistry , receptor
Bone homeostasis requires stringent regulation of osteoclasts, which secrete proteolytic enzymes to degrade the bone matrix. Despite recent progress in understanding how bone resorption occurs, the mechanisms regulating osteoclast secretion, and in particular the trafficking route of cathepsin K vesicles, remain elusive. Using a genetic approach, we describe the requirement for protein kinase C–delta (PKCδ) in regulating bone resorption by affecting cathepsin K exocytosis. Importantly, PKCδ deficiency does not perturb formation of the ruffled border or trafficking of lysosomal vesicles containing the vacuolar‐ATPase (v‐ATPase). Mechanistically, we find that cathepsin K exocytosis is controlled by PKCδ through modulation of the actin bundling protein myristoylated alanine‐rich C‐kinase substrate (MARCKS). The relevance of our finding is emphasized in vivo because PKCδ−/− mice exhibit increased bone mass and are protected from pathological bone loss in a model of experimental postmenopausal osteoporosis. Collectively, our data provide novel mechanistic insights into the pathways that selectively promote secretion of cathepsin K lysosomes independently of ruffled border formation, providing evidence of the presence of multiple mechanisms that regulate lysosomal exocytosis in osteoclasts. © 2012 American Society for Bone and Mineral Research.