How do osteoclasts break down bone matrix?

How do osteoclasts break down bone matrix?

Osteoclasts break down bone matrix through phagocytosis. Predictably, they are derived from the monocyte (macrophage) cell line. Think of osteoclasts as the “bone version” of the macrophage. Their activity occurs along their ruffled border, and the space between the osteoclast and the bone is known as Howship’s lacuna.

How does osteoclast resorb bone?

Osteoclasts Resorb Bone They closely attach to the bone matrix by binding its surface integrins to a bone protein called vitronectin. This close apposition seals off an area of the bone beneath the osteoclast and allows the osteoclast to form a microenvironment that resorbs bone.

How do osteoclasts facilitate bone resorption?

How Do Osteoclasts Resorb Bone? Bone resorption is a multistep process initiated by the proliferation of immature osteoclast precursors, the commitment of these cells to the osteoclast phenotype, and finally, degradation of the organic and inorganic phases of bone by the mature resorptive cells.

How do osteoblasts produce bone matrix?

Osteoblasts work in teams to build bone. They produce new bone called “osteoid” which is made of bone collagen and other protein. Then they control calcium and mineral deposition. Some of the osteoblasts turn into osteocytes while the new bone is being formed, and the osteocytes then get surrounded by new bone.

How do osteoblasts activate osteoclasts?

Osteoblasts activate osteoclast formation by expressing M-CSF, RANKL, and WNT5A and inhibit osteoclast activity through OPG, a decoy receptor of RANKL, SEMA3A, and WNT16. Osteocyte-derived SOST inhibits osteoblast differentiation and stimulates osteoclastogenesis.

What do osteoclasts break down bones?

The osteoclasts secrete hydrogen ions, collagenase, cathepsin K and hydrolytic enzymes into this compartment. Resorption of bone matrix by the osteoclasts involves two steps: (1) dissolution of inorganic components (minerals), and (2) digestion of organic component of the bone matrix.

How are osteoclasts activated?

Abstract. Osteoclast differentiation and activity are primarily promoted and regulated via a receptor on osteoclast lineage cells called receptor activator of nuclear factor–kappa B (RANK), which is activated through binding to its only known ligand, RANK ligand (RANKL).

How are osteoclasts formed?

Osteoclasts are formed by the fusion of many cells derived from circulating monocytes in the blood. These in turn are derived from the bone marrow.

Does osteoclasts secrete bone matrix?

Osteoclasts secrete bone matrix and become osteoblasts. Osteoblasts are large, multinucleated cells that break down calcified bone matrix.

How do osteoblasts regulate osteoclasts?

Osteoblasts regulate osteoclasts via the receptor activator of nuclear factor κ-B ligand (RANKL)-receptor activator of nuclear factor κ-B (RANK) signaling pathway. RANKL is expressed on osteoblasts and T cells. It binds the receptor RANK, which is produced on osteoclasts and their progenitors.

How do you activate osteoblasts?

Osteoblasts will be chemically fixed and their ability to activate associated cells by cell to cell contact analyzed. Osteoblast differentiation will be followed by expression of cell surface determinants on inducible precursor cell lines.

How do osteoclasts attach to the bone matrix?

Osteoclasts are giant cells containing between 10 and 20 nuclei. They closely attach to the bone matrix by binding its surface integrins to a bone protein called vitronectin. This close apposition seals off an area of the bone beneath the osteoclast and allows the osteoclast to form a microenvironment that resorbs bone.

How do osteoclasts dissolve bone mineral?

Osteoclasts dissolve bone mineral by massive acid secretion and secrete specialized proteinases that degrade the organic matrix, mainly type I collagen, in this acidic milieu.

What is the ruffled border of osteoclast?

The area of the osteoclast next to bone forms a “ruffled border” consisting of multiple infoldings of the osteoclast cell membrane. It secretes acid and proteases across the ruffled border, and these dissolve the mineral of bone and destroy the organic matrix (see Figure 9.8.4 ).

What are osteoclasts and what do they do?

Osteoclasts are multinucleated cells that play a crucial role in bone resorption. The imbalance between bone resorption and bone formation results in osteoporosis. Therefore, substances that can suppress osteoclast formation are potential candidate materials for drug development or functional foods.