Osteoclastic Tartrate-resistant Acid Phosphatase (Acp 5): Its Localization to Dendritic Cells and Diverse Murine Tissues

Abstract

SUMMARY Tartrate-resistant acid phosphatase (TRAP) is a histochemical marker of the osteoclast. It is also characteristic of monohistiocytes, particularly alveolar macrophages, and is associated with diverse pathological conditions, including hairy cell leukemia and AIDS encephalopathy. To study the biology of this enzyme, we investigated its expression and activity in mouse tissues. Confocal fluorescence studies showed that TRAP is localized to the lysosomal compartment of macrophages. In adult mice, high activities of the enzyme were demonstrated in bone, spleen, liver, thymus, and colon, with lower amounts in lung, stomach, skin, brain, and kidney. Trace amounts were detected in testis, muscle, and heart. Expression of TRAP mRNA was investigated in tissue sections by in situ hybridization and protein expression was monitored by histochemical staining or immunohistochemically. TRAP is widely expressed in many tissues, where it is associated with cells principally originating from the bone marrow, including those of osteoclast/macrophage lineage. The cellular distribution of TRAP mRNA and enzyme antigen in the tissues corresponds closely to that of cells staining with an antibody directed to the CD80 (B7) antigen. Therefore, to confirm its putative localization in dendritic cells, isolated bone marrow dendritic cells were matured in culture. These co-stained strongly for TRAP protein and the CD80 antigen. These studies demonstrate that TRAP is a lysosomal enzyme that is found in diverse murine tissues, where it is expressed in dendritic cells as well as osteoclasts and macrophages, as previously shown.

Interactions between microenvironment and cancer cells in two animal models of bone metastasis

“…The few RANKL þ cells found at the periphery of subcutaneous tumours were probably Langerhans cells. Tartrate-resistant acid phosphatasepositive cells encountered both in invaded and non-invaded spleens probably corresponded to activated macrophages, a condition previously noted by others (Hayman et al, 2000). Tartrate-resistant acid phosphatase-positive cells were previously observed in the stroma of bone tumours (Yam et al, 1987).…”

Structure, function, and regulation of tartrate-resistant acid phosphatase

“…30 Within adult tissues, the cellular sites of TRAP expression have been difficult to determine with confidence, because the histochemical assay is not definitive for TRAP when used at the limits of sensitivity. Angel et al 6 and Hayman et al 50 analyzed TRAP in adult mouse tissues. Northern blot detected TRAP mRNA in spleen, thymus, liver, lung, skin, kidney, stomach, and small intestines, whereas transcripts were absent from testis, brain, heart, and skeletal muscle.…”

Expression and secretion of the novel adipokine tartrate-resistant acid phosphatase from adipose tissues of obese and lean women

“…4 TRAP is highly expressed by osteoclasts and by sub-populations of macrophages, epithelial cells and neurons. 5,6 In vivo, TRAP 5b has previously been proposed to function as a generator of reactive oxygen species and as a protein phosphatase regulating the bioactivity of osteopontin. [7][8][9] Recently, we showed that TRAP 5a, but not TRAP 5b, induces obesity in mice and is increased in the adipose tissue of obese humans.…”