Stenbeck Gudrun
Bone and Mineral Centre, Royal Free and University College Medical School, Rayne Building, , London, WC1E 6JJ, UK.
Semin Cell Dev Biol. 2002 Aug;13(4):285-92. doi: 10.1016/s1084952102000587.
Osteoclasts are multinucleated hematopoietic cells specialised for bone resorption. Dissolution of the inorganic fraction of the bone matrix is mediated by acidification of the bone surface in contact with the osteoclast whereas secreted lysosomal enzymes digest organic components. Through massive exocytosis, the plasma membrane in contact with the bone surface enlarges into the ruffled border, which has unusual features more similar to endosomal/lysosomal membranes. Maintenance of the ruffled border during resorption is achieved through a balance between exocytosis and endocytosis. Inactivation of proteins necessary for the extracellular acidification or of the proteases involved in matrix degradation leads to osteopetrosis; a disease characterised by dense bones.
破骨细胞是专门负责骨吸收的多核造血细胞。骨基质无机成分的溶解是通过与破骨细胞接触的骨表面酸化介导的，而分泌的溶酶体酶则消化有机成分。通过大量胞吐作用，与骨表面接触的质膜扩展形成皱褶缘，其具有与内体/溶酶体膜更相似的特殊特征。在吸收过程中，通过胞吐作用和内吞作用之间的平衡来维持皱褶缘。细胞外酸化所需蛋白质或参与基质降解的蛋白酶失活会导致骨硬化症；这是一种以骨骼致密为特征的疾病。
