Tartrate-resistant acid phosphatase

About: Tartrate-resistant acid phosphatase is a research topic. Over the lifetime, 1115 publications have been published within this topic receiving 45937 citations. The topic is also known as: HPAP & SPENCDI.

Inhibitory effect of okadaic acid on the p-nitrophenyl phosphate phosphatase activity of protein phosphatases.

Abstract: The phosphatase activities of type 2A, type 1 and type 2C protein phosphatase preparations were measured against p-nitrophenyl phosphate (pNPP), a commonly used substrate for alkaline phosphatases. Of the three types of phosphatase examined, the type 2A phosphatase exhibited an especially high pNPP phosphatase activity (119 +/- 8 mumol/min per mg of protein; n = 4). This activity was strongly inhibited by pico- to nano-molar concentrations of okadaic acid, a potent inhibitor of type 2A and type 1 protein phosphatases that has been shown to have no effect on alkaline phosphatases. The dose-inhibition relationship was markedly shifted to the right and became steeper by increasing the concentration of the enzyme, as predicted by the kinetic theory for tightly binding inhibitors. The enzyme concentration estimated by titration with okadaic acid agreed well with that calculated from the protein content and the molecular mass for type 2A phosphatase. These results strongly support the idea that the pNPP phosphatase activity is intrinsic to type 2A protein phosphatase and is not due to contamination by alkaline phosphatases. pNPP was also dephosphorylated, but at much lower rates, by type 1 phosphatase (6.4 +/- 8 nmol/min per mg of protein; n = 4) and type 2C phosphatase (1.2 +/- 3 nmol/min per mg of protein; n = 4). The pNPP phosphatase activity of the type 1 phosphatase preparation shows a susceptibility to okadaic acid similar to that of its protein phosphatase activity, whereas it was interestingly very resistant to inhibitor 2, an endogenous inhibitory factor of type 1 protein phosphatase. The pNPP phosphatase activity of type 2C phosphatase preparation was not affected by up to 10 microM-okadaic acid.

miR-29b negatively regulates human osteoclastic cell differentiation and function: implications for the treatment of multiple myeloma-related bone disease.

Abstract: Skeletal homeostasis relies upon a fine tuning of osteoclast (OCL)-mediated bone resorption and osteoblast (OBL)-dependent bone formation. This balance is unsettled by multiple myeloma (MM) cells, which impair OBL function and stimulate OCLs to generate lytic lesions. Emerging experimental evidence is disclosing a key regulatory role of microRNAs (miRNAs) in the regulation of bone homeostasis suggesting the miRNA network as potential novel target for the treatment of MM-related bone disease (BD). Here, we report that miR-29b expression decreases progressively during human OCL differentiation in vitro. We found that lentiviral transduction of miR-29b into OCLs, even in the presence of MM cells, significantly impairs tartrate acid phosphatase (TRAcP) expression, lacunae generation, and collagen degradation, which are relevant hallmarks of OCL activity. Accordingly, expression of cathepsin K and metalloproteinase 9 (MMP9) as well as actin ring rearrangement were impaired in the presence of miR-29b. Moreover, we found that canonical targets C-FOS and metalloproteinase 2 are suppressed by constitutive miR-29b expression which also downregulated the master OCL transcription factor, NAFTc-1. Overall, these data indicate that enforced expression of miR-29b impairs OCL differentiation and overcomes OCL activation triggered by MM cells, providing a rationale for miR-29b-based treatment of MM-related BD.

Aging increases stromal/osteoblastic cell-induced osteoclastogenesis and alters the osteoclast precursor pool in the mouse.

Abstract: Stromal/osteoblastic cell expression of RANKL and M-CSF regulates osteoclastogenesis. We show that aging is accompanied by increased RANKL and M-CSF expression, increased stromal/osteoblastic cell-induced osteoclastogenesis, and expansion of the osteoclast precursor pool. These changes correlate with age-related alterations in the relationship between osteoblasts and osteoclasts in cancellous bone. Introduction: Bone mass is maintained through a balance between osteoblast and osteoclast activity. Osteoblasts regulate the number and activity of osteoclasts through expression of RANKL, osteoprotegerin (OPG), and macrophage-colony stimulation factor (M-CSF). To determine whether age-related changes in stromal/osteoblastic cell expression of RANKL, OPG, and M-CSF are associated with stimulation of osteoclastogenesis and whether the osteoclast precursor pool changes with age, we studied cultures of stromal/osteoblastic cells and osteoclast precursor cells from animals of different ages and examined how aging influences bone cell populations in vivo. Materials and Methods: Osteoclast precursors from male C57BL/6 mice of 6 weeks (young), 6 months (adult), and 24 months (old) of age were either co-cultured with stromal/osteoblastic cells from young, adult, or old mice or treated with M-CSF, RANKL, and/or OPG. Osteoclast precursor pool size was determined by fluorescence-activated cell sorting (FACS), and osteoclast formation was assessed by measuring the number of multinucleated TRACP+ cells and pit formation. The levels of mRNA for RANKL, M-CSF, and OPG were determined by quantitative RT-PCR, and transcription was measured by PCR-based run-on assays. Osteoblast and osteoclast numbers in bone were measured by histomorphometry. Results: Osteoclast formation increased dramatically when stromal/osteoblastic cells from old compared with young donors were used to induce osteoclastogenesis. Regardless of the origin of the stromal/osteoblastic cells, the number of osteoclasts formed from the nonadherent population of cells increased with increasing age. Stromal/osteoblastic cell expression of RANKL and M-CSF increased, whereas OPG decreased with aging. Exogenously administered RANKL and M-CSF increased, dose-dependently, osteoclast formation from all donors, but the response was greater in cells from old donors. Osteoclast formation in vitro positively, and the ratio of osteoblasts to osteoclasts in vivo negatively, correlated with the ratio of RANKL to OPG expression in stromal/osteoblastic cells for all ages. The effects of RANKL-induced osteoclastogenesis in vitro were blocked by OPG, suggesting a causal relationship between RANKL expression and osteoclast-inducing potential. The osteoclast precursor pool and expression of RANK and c-fms increased with age. Conclusions: Our results show that aging significantly increases stromal/osteoblastic cell-induced osteoclastogenesis, promotes expansion of the osteoclast precursor pool and alters the relationship between osteoblasts and osteoclasts in cancellous bone.

Formation of multinucleated cells that respond to osteotropic hormones in long term human bone marrow cultures.

Abstract: Studies of osteoclasts and their precursors in normal and pathological states have been severely hampered by the lack of an in vitro system for forming osteoclasts. We developed a human marrow culture system in which multinucleated cells with several characteristics of osteoclasts form. Multinucleated cells began to form during the first week of culture, with maximum numbers formed after 3 weeks. PTH (25–50 ng/ml) and 1,25-dihydroxyvitamin D3 (10-10–10-8M) increased formation of these cells, and these effects were inhibited by calcitonin. These multinucleated cells contained nonspecific esterase and tartrate-resistant acid phosphatase, a marker enzyme of osteoclasts, and had several ultrastructural features of osteoclasts. We used this marrow cell culture technique to study a patient with hyperparathyroidism and markedly increased osteoclasts on bone marrow biopsy. The marrow from this patient formed increased numbers of multinucleated cells in vitro. After parathyroidectomy both multinucleated cell forma...

Involvement of toll-like receptor 2 and 4 in association between dyslipidemia and osteoclast differentiation in apolipoprotein E deficient rat periodontium

Abstract: Dyslipidemia increases circulating levels of oxidized low-density lipoprotein (OxLDL) and this may induce alveolar bone loss through toll-like receptor (TLR) 2 and 4. The purpose of this study was to investigate the effects of dyslipidemia on osteoclast differentiation associated with TLR2 and TLR4 in periodontal tissues using a rat dyslipidemia (apolipoprotein E deficient) model. Levels of plasma OxLDL, and the cholesterol and phospholipid profiles in plasma lipoproteins were compared between apolipoprotein E-deficient rats (16-week-old males) and wild-type (control) rats. In the periodontal tissue, we evaluated the changes in TLR2, TLR4, receptor activator of nuclear factor kappa B ligand (RANKL) and tartrate resistant acid phosphatase (TRAP) expression. Apolipoprotein E-deficient rats showed higher plasma levels of OxLDL than control rats (p<0.05), with higher plasma levels of total cholesterol (p<0.05) and LDL-cholesterol (p<0.05) and lower plasma levels of high-density lipoprotein cholesterol (p<0.05). Their periodontal tissue also exhibited a higher ratio of RANKL-positive cells and a higher number of TRAP-positive osteoclasts than control rats (p<0.05). Furthermore, periodontal gene expression of TLR2, TLR4 and RANKL was higher in apolipoprotein E-deficient rats than in control rats (p<0.05). These findings underscore the important role for TLR2 and TLR4 in mediating the osteoclast differentiation on alveolar bone response to dyslipidemia.