| First Author | de Rooij KE | Year | 2015 |
| Journal | Histochem Cell Biol | Volume | 144 |
| Issue | 1 | Pages | 1-11 |
| PubMed ID | 25850409 | Mgi Jnum | J:319833 |
| Mgi Id | MGI:6839109 | Doi | 10.1007/s00418-015-1319-1 |
| Citation | de Rooij KE, et al. (2015) Identification of receptor-type protein tyrosine phosphatase mu as a new marker for osteocytes. Histochem Cell Biol 144(1):1-11 |
| abstractText | Osteocytes are the predominant cells in bone, where they form a cellular network and display important functions in bone homeostasis, phosphate metabolism and mechanical transduction. Several proteins strongly expressed by osteocytes are involved in these processes, e.g., sclerostin, DMP-1, PHEX, FGF23 and MEPE, while others are upregulated during differentiation of osteoblasts into osteocytes, e.g., osteocalcin and E11. The receptor-type protein tyrosine phosphatase micro (RPTPmu) has been described to be expressed in cells which display a cellular network, e.g., endothelial and neuronal cells, and is implied in mechanotransduction. In a capillary outgrowth assay using metatarsals derived from RPTPmu-knock-out/LacZ knock-in mice, we observed that the capillary structures grown out of the metatarsals were stained blue, as expected. Surprisingly, cells within the metatarsal bone tissue were positive for LacZ activity as well, indicating that RPTPmu is also expressed by osteocytes. Subsequent histochemical analysis showed that within bone, RPTPmu is expressed exclusively in early-stage osteocytes. Analysis of bone marrow cell cultures revealed that osteocytes are present in the nodules and an enzymatic assay enabled the quantification of the amount of osteocytes. No apparent bone phenotype was observed when tibiae of RPTPmu-knock-out/LacZ knock-in mice were analyzed by muCT at several time points during aging, although a significant reduction in cortical bone was observed in RPTPmu-knock-out/LacZ knock-in mice at 20 weeks. Changes in trabecular bone were more subtle. Our data show that RPTPmu is a new marker for osteocytes. |
