Osteoclasts from Mice Deficient in Tartrate-Resistant Acid Phosphatase Have Altered Ruffled Borders and Disturbed Intracellular Vesicular Transport

Hollberg, Karin; Hultenby, Kjell; Hayman, Alison R.; Cox, Timothy M.; Andersson, Göran

doi:10.1006/excr.2002.5612

Cited by 96 publications

(59 citation statements)

References 55 publications

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“…Our RT-PCR and Western blot analysis on bone extracts and immunohistochemistry on bone tissue sections clearly indicated a higher expression of cathepsin K versus L in trabecular osteoclasts and, moreover, indicated that the majority of cathepsin K protein was processed to the active form and co-localized with TRAP in osteoclasts, whereas the majority of cathepsin L was present as the inactive precursor form and did not co-localize to a significant extent with TRAP in osteoclasts. Osteoclasts secrete TRAP (12,74,75) as well as cathepsin K (32,76) into the resorption lacuna. In order to define the potential sites of cathepsin Kmediated processing of TRAP, we assessed the subcellular distribution of cathepsin K and the monomeric and proteolytically processed TRAP by ultrastructural immunocytochemistry.…”

Section: Discussionmentioning

confidence: 99%

“…After extraction, the RNA was treated with 5 units of DNase I (Invitrogen) for 30 min at room temperature. The reverse transcriptase reaction was performed with 5 g of total RNA and 200 units of Superscript TM II reverse transcriptase (Invitrogen) at 42°C, using (dT) [12][13][14][15][16][17][18] as primer (Invitrogen), according to the protocol of the manufacturer. In negative controls, reverse transcriptase was excluded from the reaction mixture.…”

Section: Relative Quantification Of Cathepsin K and L Mrnamentioning

confidence: 99%

“…The tissue used for immunoelectron microscopy was fixed by immersion in a 0.1 M phosphate-buffered (PB) mixture of 2% paraformaldehyde with 0.5% glutaraldehyde and decalcified in EDTA (triplex II) as described previously (12). Tibia was cut in smaller pieces and dehydrated in methanol at low temperature in a Leica AFS (Leica, Heerbrugg, Switzerland) and embedded in Lowicryl K11M (Chemische Werke Lowi GmbH, Waldkreiburg, Germany) at low temperature as described previously (58).…”

Section: Ultrastructural Immunohistochemistrymentioning

confidence: 99%

“…The precise role of osteoclastic TRAP is not fully understood, but studies on TRAP knock-out mice showed disturbed endochondral ossification with decreased resorptive activity of osteoclasts (11,12), whereas overexpression of TRAP was associated with increased bone turnover (10). Different functions have been suggested for TRAP, e.g.…”

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confidence: 99%

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Proteolytic Excision of a Repressive Loop Domain in Tartrate-resistant Acid Phosphatase by Cathepsin K in Osteoclasts

Ljusberg¹,

Wang²,

Lång³

et al. 2005

Journal of Biological Chemistry

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125

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Tartrate-resistant acid phosphatase (TRAP) is a metallophosphoesterase participating in osteoclast-mediated bone turnover. Activation of TRAP is associated with the redox state of the di-iron metal center as well as with limited proteolytic cleavage in an exposed loop domain. The cysteine proteinases cathepsin B, L, K, and S as well as the matrix metalloproteinase-2, -9, -13, and -14 are expressed by osteoclasts and/or other bone cells and have been implicated in the turnover of bone and cartilage. To identify proteases that could act as activators of TRAP in bone, we report here that cathepsins K and L, in contrast to the matrix metalloproteinases, efficiently cleaved and activated recombinant TRAP in vitro. Activation of TRAP by cathepsin K/L was because of increases in catalytic activity, substrate affinity, and sensitivity to reductants. Processing by cathepsin K occurred sequentially by an initial excision of the loop peptide Gly Tartrate-resistant acid phosphatase (TRAP), 1 also known as type 5 acid phosphatase (EC 3.1.3.2) or uteroferrin, belongs to the purple acid phosphatase (PAP) subfamily of the non-heme dinuclear metallophosphatases (1-3). The metals of the catalytic center of all PAPs consist of a common ferric ion and a divalent metal cation in an active enzyme, where mammalian PAPs characteristically contain a redox-active iron in the M(II) site (4 -6).The TRAP enzyme is abundantly expressed by bone-resorbing cells, osteoclasts, and certain subpopulations of monocytes/ macrophages and dendritic cells (7-10). The precise role of osteoclastic TRAP is not fully understood, but studies on TRAP knock-out mice showed disturbed endochondral ossification with decreased resorptive activity of osteoclasts (11, 12), whereas overexpression of TRAP was associated with increased bone turnover (10). Different functions have been suggested for TRAP, e.g. as an osteopontin phosphatase (13-15), generation of reactive oxygen species (16 -19), iron transport (20 -24), and as a growth/differentiation factor for hematopoietic (25) and osteoblastic (26) cells.Mammalian PAPs are synthesized as 35-37-kDa monomers but are commonly isolated from tissues as proteolytically cleaved two-subunit forms consisting of a 23-kDa N-terminal domain disulfide-linked to a 16-kDa C-terminal domain. The monomeric form exhibits properties of a proenzyme with low phosphatase activity that is converted to a high activity, twosubunit form upon proteolytic cleavage in the intervening loop domain with either serine proteases, e.g. trypsin or chymotrypsin (27), or members of the cathepsin family (28,29). Mutagenesis studies suggested that proteolysis removes or alters repressive interactions between loop amino acids and active site residues because replacement of Asp 146 of the exposed loop domain with Ala resulted in activation of unproteolyzed TRAP (30).Several lines of evidence indicate a role for cathepsin K in bone resorption. Cathepsin K is highly expressed in osteoclasts near the ruffled border membrane and has been shown to participate i...

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Section: Discussionmentioning

confidence: 99%

Section: Relative Quantification Of Cathepsin K and L Mrnamentioning

confidence: 99%

Section: Ultrastructural Immunohistochemistrymentioning

confidence: 99%

mentioning

confidence: 99%

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Proteolytic Excision of a Repressive Loop Domain in Tartrate-resistant Acid Phosphatase by Cathepsin K in Osteoclasts

Ljusberg¹,

Wang²,

Lång³

et al. 2005

Journal of Biological Chemistry

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125

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“…Femoral bones from WT and TRAP+p mice were prepared for immunohistochemistry as described previously [Hollberg et al, 2002]. In order to detect cathepsin K, total TRAP (i.e.…”

Section: Immunohistochemistry For Light Microscopymentioning

confidence: 99%

Transgenic Overexpression of Tartrate-Resistant Acid Phosphatase Is Associated with Induction of Osteoblast Gene Expression and Increased Cortical Bone Mineral Content and Density

Gradin

Hollberg

Cassady

et al. 2012

Cells Tissues Organs

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Bone remodeling is a central event in the maintenance of skeletal tissue, and involves cycles of resorption followed by the formation of bone tissue. The activity of osteoclasts and osteoblasts during these cycles is tightly regulated by systemic and local factors coupling the action of these cells. Tartrate-resistant acid phosphatase (TRAP) is predominantly expressed in bone by osteoclasts but has also been detected in osteoblasts and osteocytes. Moreover, TRAP can stimulate the differentiation of mesenchymal lineage cells, i.e. progenitors of osteoblasts and adipocytes. In order to further explore the effects of TRAP on bone turnover, the structural and molecular phenotypes of osteoclasts and osteoblasts were assessed in TRAP-overexpressing transgenic mice. Transgenic mice of both sexes display increased cortical bone mineral content and density, which cannot be accounted for by decreased bone resorption since osteoclast numbers and resorptive activity do not differ from wild-type mice. Examination of the osteoblast phenotype revealed that markers of bone formation, i.e. procollagen type I N-terminal propeptides, and osteoblast lineage markers as well as the TRAP 1B mRNA transcript are increased in TRAP-overexpressing mice. Expression of the osteoclast-selective TRAP 1C mRNA is not increased in TRAP transgenic mice. Elevated expression of TRAP mRNA and protein were detected in osteoblasts, osteocytes and in the bone matrix of TRAP transgenic mice, suggesting that TRAP overexpression in osteoblast lineage cells is associated with increased cortical bone mineral content and density. The data presented here support the hypothesis that TRAP overexpression in the osteoblastic cell lineage stimulates the differentiation and/or activation of these cells.

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Tartrate‐resistant acid phosphatase: a potential target for therapeutic gold

Hayman¹,

Cox²

2004

Cell Biochemistry & Function

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Gold compounds are disease-modifying agents for the treatment of rheumatoid arthritis. They act on the immune system but the mechanism is not fully understood. Gold has been shown to affect antigen processing by T-cells and also reduces expression of cytokines in macrophages. Tartrate-resistant acid phosphatase (TRAP), expressed by osteoclasts, macrophages and dendritic cells is an enzyme with roles in skeletal metabolism and the immune response. TRAP is able to degrade skeletal phosphoproteins including osteopontin, identical to the T-cell cytokine, Eta-1; we thus propose that TRAP regulates the Eta-1 pathway common to the immune system and skeleton. We compared the distribution of osteopontin and TRAP in sections of 18-day-old embryonic mice by immunohistochemistry. Both proteins occurred in the same locations. To determine whether gold compounds exert their effects by modification of TRAP activity, we examined the action of gold chloride and the prodrugs, aurothioglucose and aurothiomalate on the dephosphorylation of osteopontin by TRAP. Aurothioglucose and aurothiomalate had little effect on phosphatase activity; gold chloride was a potent non-competitive inhibitor (Ki < 47 x 10(-9) M). These findings indicate a possible molecular mechanism for the action of therapeutic gold and further implicate TRAP in the control of immunity.

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Osteoclasts from Mice Deficient in Tartrate-Resistant Acid Phosphatase Have Altered Ruffled Borders and Disturbed Intracellular Vesicular Transport

Cited by 96 publications

References 55 publications

Proteolytic Excision of a Repressive Loop Domain in Tartrate-resistant Acid Phosphatase by Cathepsin K in Osteoclasts

Proteolytic Excision of a Repressive Loop Domain in Tartrate-resistant Acid Phosphatase by Cathepsin K in Osteoclasts

Transgenic Overexpression of Tartrate-Resistant Acid Phosphatase Is Associated with Induction of Osteoblast Gene Expression and Increased Cortical Bone Mineral Content and Density

Tartrate‐resistant acid phosphatase: a potential target for therapeutic gold

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