Dataset Information

Autophagy proteins regulate the secretory component of osteoclastic bone resorption.

ABSTRACT: Osteoclasts resorb bone via the ruffled border, whose complex folds are generated by secretory lysosome fusion with bone-apposed plasma membrane. Lysosomal fusion with the plasmalemma results in acidification of the resorptive microenvironment and release of CatK to digest the organic matrix of bone. The means by which secretory lysosomes are directed to fuse with the ruffled border are enigmatic. We show that proteins essential for autophagy, including Atg5, Atg7, Atg4B, and LC3, are important for generating the osteoclast ruffled border, the secretory function of osteoclasts, and bone resorption in vitro and in vivo. Further, Rab7, which is required for osteoclast function, localizes to the ruffled border in an Atg5-dependent manner. Thus, autophagy proteins participate in polarized secretion of lysosomal contents into the extracellular space by directing lysosomes to fuse with the plasma membrane. These findings are in keeping with a putative link between autophagy genes and human skeletal homeostasis.

SUBMITTER: DeSelm CJ

PROVIDER: S-EPMC3244473 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Autophagy proteins regulate the secretory component of osteoclastic bone resorption.

DeSelm Carl J CJ Miller Brian C BC Zou Wei W Beatty Wandy L WL van Meel Eline E Takahata Yoshifumi Y Klumperman Judith J Tooze Sharon A SA Teitelbaum Steven L SL Virgin Herbert W HW

Developmental cell 20111104 5

Osteoclasts resorb bone via the ruffled border, whose complex folds are generated by secretory lysosome fusion with bone-apposed plasma membrane. Lysosomal fusion with the plasmalemma results in acidification of the resorptive microenvironment and release of CatK to digest the organic matrix of bone. The means by which secretory lysosomes are directed to fuse with the ruffled border are enigmatic. We show that proteins essential for autophagy, including Atg5, Atg7, Atg4B, and LC3, are important ...[more]

PMID: 22055344

Similar Datasets

Project description:Skeletal health is maintained by bone remodeling, a process in which microscopic sites of effete or damaged bone are degraded on bone surfaces by osteoclasts and subsequently replaced by new bone, which is laid down by osteoblasts. This normal process can be disturbed in a variety of pathologic processes, including localized or generalized inflammation, metabolic and endocrine disorders, primary and metastatic cancers, and during aging as a result of low-grade chronic inflammation. Osteoclast formation and activity are promoted by factors, including cytokines, hormones, growth factors, and free radicals, and require expression of macrophage-colony stimulating factor (M-CSF) and receptor activator of NF-?B ligand (RANKL) by accessory cells in the bone marrow, including osteoblastic and immune cells. Expression of TNF receptor-associated factor 6 (TRAF6) is required in osteoclast precursors to mediate RANKL-induced activation of NF-?B, which is also necessary for osteoclast formation and activity. TRAF3, in contrast is not required for osteoclast formation, but it limits RANKL-induced osteoclast formation by promoting proteasomal degradation of NF-?B-inducing kinase in a complex with TRAF2 and cellular inhibitor of apoptosis proteins (cIAP). TRAF3 also limits osteoclast formation induced by TNF, which mediates inflammation and joint destruction in inflammatory diseases, including rheumatoid arthritis. Chloroquine and hydroxychloroquine, anti-inflammatory drugs used to treat rheumatoid arthritis, prevent TRAF3 degradation in osteoclast precursors and inhibit osteoclast formation in vitro. Chloroquine also inhibits bone destruction induced by ovariectomy and parathyroid hormone in mice in vivo. Mice genetically engineered to have TRAF3 deleted in osteoclast precursors and macrophages develop early onset osteoporosis, inflammation in multiple tissues, infections, and tumors, indicating that TRAF3 suppresses inflammation and tumors in myeloid cells. Mice with TRAF3 conditionally deleted in mesenchymal cells also develop early onset osteoporosis due to a combination of increased osteoclast formation and reduced osteoblast formation. TRAF3 protein levels decrease in bone and bone marrow during aging in mice and humans. Development of drugs to prevent TRAF3 degradation in immune and bone cells could be a novel therapeutic approach to prevent or reduce bone loss and the incidence of several common diseases associated with aging.

Dataset Information

Autophagy proteins regulate the secretory component of osteoclastic bone resorption.

Publications

Autophagy proteins regulate the secretory component of osteoclastic bone resorption.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure