Bone Abstracts

Introduction: Osteoclasts are the only cells with the capacity to degrade mineralized matrices, such as bone and calcified cartilage. During bone remodeling, osteoclasts secrete protons to achieve the acidic dissolution of hydroxyapatite to make bone collagen amenable to digestion by the proteases they produce. This requires the sealing zone, a ring of densely packed podosomes that surrounds the ruffled border, which is the secretion apparatus of the bone resorbing osteoclasts...

Osteoclasts resorb bone matrix through a specific adhesion structure called the sealing zone or actin ring, which is based on a belt of podosome. Much remains to be uncovered regarding the molecular mechanisms driving podosome organization into superstructures in particular the osteoclast podosome belt. Proteomic analyses in osteoclasts revealed the adaptor protein tensin 3 as a partner of Dock5, a Rac exchange factor necessary for podosome belt formation and bone resorption. ...