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OPN Protein (opn + protein)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Increased osteopontin expression following intranigral lipopolysaccharide injection in the rat

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2005
Joanna Iczkiewicz
Abstract Nigral cell death in Parkinson's disease is characterized by glial cell activation leading to inflammatory changes. Osteopontin (OPN) is a glycosylated phosphoprotein that is induced by inflammatory mediators and which we have previously shown to be present in the substantia nigra. However, the role of OPN in the nigral inflammation is not known. We now report on the effects of lipopolysaccharide (LPS)-induced glial cell activation in the substantia nigra of rats on OPN expression. LPS administration induced dopaminergic cell death as shown by reduced nigral tyrosine hydroxylase immunoreactivity. There was a corresponding time-dependent increase in both OPN mRNA, which was maximal at 48 h, and protein levels, which peaked at 72 h before returning to control levels by 120 h. This increase was accompanied by marked reactive gliosis as shown by increased OX-42, glial fibrillary acidic protein (GFAP) and ED1 immunoreactivity. OX-42-positive cells increased in a time-dependent manner, peaking at 72 h before returning to control levels at 120 h. Similarly, ED1-positive cells were present in their greatest numbers at 24 h but then gradually declined. These changes mirrored the alterations occurring in OPN protein and OPN mRNA, respectively. In contrast, GFAP-positive cells only started to increase in number at 120 h. Colocalization studies showed that OPN was present in both ED1- and OX-42-positive cells but not in GFAP-positive cells. These data confirm that intranigral injection of LPS induces a rapid and marked gliosis that accompanies the loss of tyrosine hydroxylase-positive neurones and suggest that, after glial cell activation, enhanced expression of OPN occurs linked to increased numbers of microglia and/or macrophages. This suggests that OPN may be functionally important in the control of inflammatory changes. [source]

Osteopontin expression correlates with prognostic variables and survival in clear cell renal cell carcinoma

JOURNAL OF SURGICAL ONCOLOGY, Issue 4 2006
Koviljka Matusan MD
Abstract Background and Objectives Osteopontin (OPN) is a phosphorylated glycoprotein with diverse functions including tumorigenesis and tumor cell metastasis. Recently, it has been detected in a growing number of human tumors, and assessed as a potential prognostic marker. The aim of this study was to analyze the expression of OPN in normal renal tissue and clear cell renal cell carcinomas (CRCCs), and to assess its prognostic significance. Methods The expression of OPN protein was immunohistochemically analyzed in 171 CRCCs and compared to usual clinicopathological parameters such as tumor size, nuclear grade, pathological stage, Ki-67 proliferation index, and cancer-specific survival. Results In normal renal parenchyma, the expression of OPN was seen in distal tubular epithelial cells, calcifications, and some stromal cells. The upregulation of OPN was observed in 61 CRCCs (35.7%) in the form of cytoplasmic granular staining of various intensities. Statistical analysis showed correlation of the OPN expression with tumor size (P,<,0.001), Fuhrman nuclear grade (P,<,0.001), pathological stage (P,=,0.011), and Ki-67 proliferation index (P,<,0.001). Moreover, patients with OPN-positive tumors had significantly worse prognosis in comparison to patients with tumors lacking OPN protein (P,=,0.004). Conclusion Our results suggest that overexpression of OPN is involved in the progression of CRCC. J. Surg. Oncol. 2006;94:325,331. © 2006 Wiley-Liss, Inc. [source]

Expression of osteopontin messenger RNA by macrophages in ovarian serous papillary cystadenocarcinoma: A possible association with calcification of psammoma bodies

PATHOLOGY INTERNATIONAL, Issue 7 2000
Masahiko Maki
Calcified psammoma bodies often appear in human ovarian serous papillary cystadenocarcinoma. Osteocalcin (OC), osteonectin (ON) and osteopontin (OPN) are three members of non-collagenous bone-related proteins known to be related with mineralization of bone. To clarify possible involvement of these bone matrix proteins in the calcification of the psammoma bodies, the expression of OC, ON and OPN was analyzed by immunohistochemical and in situ hybridization studies using 15 surgical specimens. OPN protein was detected in the calcified area of the psammoma bodies which was positively stained by von Kóssa's staining, while OC and ON proteins were not. OPN protein was not detected in any cells in tissues, but OPN messenger ribonucleic acid (mRNA) was detected in CD68-positive macrophages, indicating that OPN was produced and promptly secreted by macrophages. These results suggest that OPN produced and promptly secreted by macrophages and subsequently translocated to psammoma bodies may be causally related with the calcium phosphate deposition in the psammoma bodies of the ovarian serous papillary cystadenocarcinomas. [source]

Osteopontin deficiency impairs wear debris,induced osteolysis via regulation of cytokine secretion from murine macrophages

ARTHRITIS & RHEUMATISM, Issue 5 2010
Sadanori Shimizu
Objective To investigate the molecular mechanisms underlying particle-induced osteolysis, we focused on osteopontin (OPN), a cytokine and cell-attachment protein that is associated with macrophage chemoattractant and osteoclast activation. Methods We compared OPN protein levels in human periprosthetic osteolysis tissues with those in osteoarthritis (OA) synovial tissues. To investigate the functions of OPN during particle-induced osteolysis in vivo, titanium particles were implanted onto the calvaria of OPN-deficient mice and their wild-type (WT) littermates. Mice were killed on day 10 and evaluated immunohistologically. The effects of OPN deficiency on the secretion of inflammatory cytokines were examined using cultured bone marrow,derived macrophages (BMMs). BMMs from OPN-deficient and WT mice were cultured with titanium particles for 12 hours, and the concentrations of inflammatory cytokines in the conditioned media were measured by enzyme-linked immunosorbent assay. Results Expression of OPN protein was enhanced in human periprosthetic osteolysis tissues as compared with OA synovial tissues. In the particle-induced model of osteolysis of the calvaria, bone resorption was significantly suppressed by OPN deficiency via inhibition of osteoclastogenesis, whereas an inflammatory reaction was observed regardless of the genotype. Results of immunostaining indicated that OPN protein was highly expressed in the membrane and bone surface at the area of bone resorption in WT mice. When BMMs were exposed to titanium particles, the concentration of proinflammatory cytokines, such as tumor necrosis factor ,, interleukin-1, (IL-1,), IL-1,, and IL-6, as well as chemotactic factors, such as monocyte chemoattractant protein 1 and macrophage inflammatory protein 1,, in the conditioned medium were significantly reduced by OPN deficiency. Whereas phagocytic activity of BMMs was not attenuated by OPN deficiency, phagocytosis-mediated NF-,B activation was impaired in OPN-deficient BMMs. These data indicated that OPN was implicated in the development of particle-induced osteolysis via the orchestration of pro-/antiinflammatory cytokines secreted from macrophages. Conclusion OPN plays critical roles in wear debris,induced osteolysis, suggesting that OPN is a candidate therapeutic target for periprosthetic osteolysis. [source]