Osteoclasts from Mice Deficient in Tartrate-Resistant Acid Phosphatase Have Altered Ruffled Borders and Disturbed Intracellular Vesicular Transport
| Autor: | Karin Hollberg, Timothy M. Cox, Alison R. Hayman, Göran Andersson, Kjell Hultenby |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Acid Phosphatase
Cathepsin K Osteoclasts Chondrocyte Bone resorption Mice Osteoclast medicine Animals Femur Growth Plate Osteopontin Tartrate-resistant acid phosphatase Mice Knockout biology Tartrate-Resistant Acid Phosphatase Acid phosphatase Cell Biology Cathepsins Cell biology Isoenzymes Vesicular transport protein Protein Transport medicine.anatomical_structure Biochemistry biology.protein Cell Surface Extensions |
| Zdroj: | Experimental Cell Research. 279:227-238 |
| ISSN: | 0014-4827 |
| DOI: | 10.1006/excr.2002.5612 |
| Popis: | Tartrate-resistant acid phosphatase (TRAP) is an enzyme highly expressed in osteoclasts (OC) and chondroclasts. As an approach to pinpoint the function of TRAP in bone-resorbing osteoclasts, the morphological phenotypic alterations of bone and osteoclasts in mice with targeted disruption of the TRAP gene were assessed by quantitative histomorphometry and immunocytochemistry at the light microscopic and ultrastructural levels. TRAP-deficient mice display alterations in the epiphyseal growth plates as evidenced by increased height with disorganized columns of chondrocytes, in particular affecting the zone of hypertrophic chondrocytes, consistent with a disturbance of chondrocyte maturation and chondroclastic resorption at the epiphyseal/metaphyseal junction. TRAP -/- mice express an early onset osteopetrotic bone phenotype, apparent already at 4 weeks of age. The differentiation of OCs was apparently normal; however, the osteoclasts in TRAP-deficient mice were less active in terms of degradation or release of the resorption marker C-terminal type I collagen cross-linked peptide, indicative of an intrinsic defect. Ultrastructural morphometry disclosed that OCs from TRAP-deficient young mice exhibited an increased relative area of ruffled borders. Moreover, mutant OC accumulated cytoplasmic vesicles 200-500 nm in size in both ruffled border and basolateral parts of the cytoplasm, reflecting disturbed intracellular transport. The accumulated vesicles were not likely derived from the secretory pathway, since cathepsin K was detected at normal levels in the ruffled border area and matrix in TRAP -/- mice. In summary, the resorptive defect in TRAP-deficient OCs is reflected by a disturbance at the level of ruffled borders and intracellular transport vesicles. Consequently, accumulation of vesicles in the cytoplasm of mutant OCs indicates a novel function for TRAP in modulating intracellular vesicular transport in osteoclasts. |
| Databáze: | OpenAIRE |
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