BACKGROUND & AIMS: :Osteopontin (OPN), a proinflammatory cytokine, plays an important role in renal fibrosis. We reported that plasma OPN levels were higher in patients with primary aldosteronism than with essential hypertension. However, the regulatory mechanism of OPN by aldosterone remains unclear. Here, we report the transcriptional regulation of OPN expression by aldosterone and the functional effects of aldosterone-mediated OPN transcription in renal fibroblasts. Aldosterone induced OPN expression in a dose-dependent manner with significant responses at 10 nmol/L (1.6+/-0.2-fold of controls, P<0.05, n=5) and elicited maximal effects at 10 micromol/L (3.5+/-0.4-fold of controls, P<0.01, n=5). Aldosterone increased OPN expression in a time-dependent manner with a maximal effect after 48 hours (2.7+/-0.3-fold of controls, P<0.01, n=5). This effect was abolished by the mineralocorticoid receptor (MR) antagonist spironolactone. Luciferase promoter deletion assays identified a novel cis regulatory element (-2153 to -1758) in the OPN promoter that is responsive to aldosterone. This element contains an activator protein-1 (AP-1) and nuclear factor kappa B (NF kappaB) site. Electrophoretic mobility shift assays, supershift assays, and chromatin immunoprecipitation assays identified both AP-1 and NF kappaB as the DNA binding proteins induced by aldosterone with spironolactone inhibiting aldosterone-induced AP-1 or NF kappaB activity. OPN-siRNA inhibited completely the induction of cell proliferation, type I, III, and IV collagen synthesis by aldosterone. These results indicate that aldosterone induced MR-mediated OPN expression through AP-1 and NF kappaB activation and suggest that aldosterone plays an important role in renal fibrosis through the induction of OPN.

背景与目标： ：骨桥蛋白（OPN）是一种促炎性细胞因子，在肾纤维化中起重要作用。我们报道，原发性醛固酮增多症患者的血浆OPN水平高于原发性高血压。但是，醛固酮对OPN的调节机制仍不清楚。在这里，我们报道了醛固酮对OPN表达的转录调控以及醛固酮介导的OPN在肾成纤维细胞中的功能作用。醛固酮以剂量依赖性方式诱导OPN表达，在10 nmol / L时有显着反应（对照组的1.6 /-0.2倍，P <0.05，n = 5），在10 micromol / L时产生最大作用（3.5 /-0.4）对照的-倍，P ＜0.01，n ＝ 5）。醛固酮以时间依赖性方式增加OPN表达，在48小时后达到最大作用（对照组的2.7 /-0.3倍，P <0.01，n = 5）。盐皮质激素受体（MR）拮抗剂螺内酯消除了该作用。萤光素酶启动子缺失测定法在OPN启动子中发现了对醛固酮有反应的新型顺式调控元件（-2153至-1758）。此元素包含激活蛋白1（AP-1）和核因子κB（NFκB）位点。电泳迁移率迁移测定，超迁移测定和染色质免疫沉淀测定均将AP-1和NF kappaB鉴定为醛固酮诱导的DNA结合蛋白，螺内酯抑制醛固酮诱导的AP-1或NF kappaB活性。 OPN-siRNA完全抑制醛固酮诱导的细胞增殖，I型，III型和IV型胶原蛋白合成。这些结果表明，醛固酮通过AP-1和NF kappaB激活诱导MR介导的OPN表达，并表明醛固酮通过诱导OPN在肾纤维化中起重要作用。

BACKGROUND & AIMS: :Osteopontin that associates with metabolism of calcium is one of the important factors in the development and prognosis of human breast cancer. The aim of this study was to detect potential binding partners of osteopontin to illustrate its functional mechanism. By screening a human breast cDNA library with a bacterial two-hybrid system, apolipoprotein D was isolated as a novel interacting protein of osteopontin. This interaction was confirmed by mammalian two-hybrid assay and co-immunoprecipitation. To elucidate the influence of ApoD on cellular neoplastic specifications, adhesion, soft agar, invasion and MTT growth assays were performed with Rama37 cells. The results revealed that expression of apolipoprotein D in Rama37 cells could significantly inhibit the malignant phenotype in osteopontin-transformed Rama37 cells. These findings provide better knowledge of the osteopontin signaling pathway and suggest that apolipoprotein D could be a prospective therapeutic agent for human breast and/or other carcinomas.

背景与目标： ：与钙代谢相关的骨桥蛋白是人类乳腺癌发展和预后的重要因素之一。这项研究的目的是检测骨桥蛋白的潜在结合伴侣，以说明其功能机制。通过用细菌双杂交系统筛选人乳腺cDNA文库，分离出载脂蛋白D作为骨桥蛋白的新型相互作用蛋白。这种相互作用已通过哺乳动物双杂交测定和免疫共沉淀得到了证实。为了阐明ApoD对细胞赘生物规格的影响，对Rama37细胞进行了粘附，软琼脂，侵袭和MTT生长测定。结果表明载脂蛋白D在Rama37细胞中的表达可以显着抑制骨桥蛋白转化的Rama37细胞的恶性表型。这些发现提供了对骨桥蛋白信号传导途径的更好的了解，并表明载脂蛋白D可能是人乳腺癌和/或其他癌症的前瞻性治疗剂。

BACKGROUND & AIMS: OBJECTIVE:To test the effects of a novel monoclonal antibody (mAb) against human osteopontin (OPN) in the prevention and treatment of collagen-induced arthritis (CIA) and to elucidate the underlying mechanisms of these effects. METHODS:DBA/1J mice immunized with type II collagen to induce CIA were monitored to assess the effects of anti-OPN mAb on the clinical severity of the disease, and pathologic changes in the joints were examined histologically. The effects of anti-OPN mAb on survival of activated T cells from arthritic mice and from the synovial fluid of patients with rheumatoid arthritis (RA) were determined by TUNEL assay or annexin V assay. The levels of apoptosis-related proteins (Bim, Bax, and Bcl-2) and NF-kappaB were detected by immunoblot analysis. RESULTS:One anti-OPN mAb, 23C3, was effective in inhibiting the development of CIA and even reversing established disease in DBA/1J mice. Monoclonal antibody 23C3 reduced the levels of serum type II collagen-specific autoantibodies and proinflammatory cytokines, and suppressed T cell recall responses to type II collagen. Mechanistic studies demonstrated that OPN prevented the death of type II collagen-activated murine T cells and synovial T cells from RA patients. Monoclonal antibody 23C3 promoted apoptosis of the activated T cells, particularly CD4+ T cells, by inhibiting activation of NF-kappaB and by altering the balance among the proapoptotic proteins Bim and Bax and the antiapoptotic protein Bcl-2. Screening of a phage display peptide library led to identification of the epitope ATWLNPDPSQKQ as being recognized by this novel antibody. CONCLUSION:Because of its ability to effectively promote apoptosis of activated T cells, mAb 23C3 may be a novel therapeutic agent for the treatment of RA.

背景与目标：

BACKGROUND & AIMS: Osteopontin (OPN) is a major glycosylated phosphoprotein in bone matrix and is produced by several cells including osteoblasts, osteoclasts and macrophages. OPN levels increase in active sites of bone metabolism. Recently, several bone-related proteins were identified in gingival crevicular fluid (GCF) to seek markers of alveolar bone resorption in periodontal disease. In this study, we investigated the existence of OPN in GCF and the correlation between OPN level in GCF and probing depth (PD) of sampling sites in 98 periodontitis patients and 35 healthy subjects. An immunoblotting analysis using 10% polyacrylamide gel showed that two forms of OPN with molecular masses of 54 and 66 kDa and several degraded fragments were detected in most GCF samples from diseased sites (PD > 4 mm). In GCF samples from healthy sites (PD < or = 3 mm), only one form (54 kDa) was observed, but any degraded fragments were not detected. When OPN amounts in GCF samples were determined by ELISA, a weak. but significant correlation was observed between OPN amount in GCF and PD (r=0.32, p=0.0013). These results demonstrate that OPN exists in GCF and that OPN level in GCF increases with the progression of periodontal disease.

背景与目标： 骨桥蛋白 (OPN) 是骨基质中主要的糖基化磷蛋白，由成骨细胞，破骨细胞和巨噬细胞等多种细胞产生。骨代谢活性部位的OPN水平增加。最近，在龈沟液 (GCF) 中发现了几种与骨相关的蛋白质，以寻找牙周病中牙槽骨吸收的标志物。在这项研究中，我们调查了98例牙周炎患者和35例健康受试者的GCF中OPN的存在以及GCF中OPN水平与采样点探测深度 (PD) 之间的相关性。使用10% 聚丙烯酰胺凝胶的免疫印迹分析表明，在来自患病部位的大多数GCF样品中检测到两种形式的具有54和66 kda的分子量的OPN和几个降解的片段 (PD> 4毫米)。在来自健康位点 (PD <或 = 3毫米) 的GCF样品中，仅观察到一种形式 (54 kda)，但未检测到任何降解的片段。当通过ELISA测定GCF样品中的OPN量时，弱。但是在GCF中的OPN量与PD之间观察到显着的相关性 (r = 0.32，p = 0.0013)。这些结果表明，GCF中存在OPN，GCF中的OPN水平随着牙周病的进展而增加。

BACKGROUND & AIMS: BACKGROUND:It has been suggested that trophoblast attachment requires co-expression of integrin alpha V beta 3 and its ligand osteopontin at the fetal-maternal interface. Until now the expression patterns of integrin alpha V beta 3 and osteopontin in the pregnant bovine uterus were unknown. The objectives of this study were to localize integrin alpha V beta 3 and osteopontin in bovine and sheep endometrium during the periimplantation period and to compare the distribution patterns using antibodies that had not yet been tested in sheep. METHODS:Cell compartments within endometrial tissue sections were scored for immunohistochemical staining intensity and data were analyzed to determine the effects of day of pregnancy or cycle. RESULTS:In pregnant bovine endometrium, integrin alpha V beta 3 was detected in luminal epithelium, stroma, myometrium and smooth muscle. A strong band of immunoreactivity was observed in the subepithelial stroma of intercaruncular regions, but there was reduced reactivity in the caruncles and glands. Bovine trophoblast did not express integrin alpha V beta 3 at any stage of pregnancy. In ovine endometrium a different pattern of staining for integrin alpha V beta 3 was observed. Reactivity was not present in the luminal epithelium or trophoblast. There was strong staining of the deep glands and no reactivity in the superficial glands. Osteopontin distribution was similar for sheep and cattle. For both species, apical staining was present on the luminal epithelium and glands and on embryonic tissues. CONCLUSION:In ruminants, integrin alpha V beta 3 and osteopontin do not co-localize at the fetal-maternal interface indicating that these proteins could not interact to facilitate embryo attachment as has been proposed in other species.

背景与目标：

BACKGROUND & AIMS: :Osteopontin (OPN) is an extracellular matrix glycophosphoprotein produced by several types of cells including the immune system. The present study examined the possibility that single-nucleotide polymorphisms (SNP) in the promoter region of the OPN at nt -443 is a marker predicting the therapeutic efficacy of pegylated interferon (peg-IFN-α2b)-ribavirin combination therapy in Egyptian patients with chronic hepatitis C. Blood was collected from 95 patients with chronic hepatitis C who had received peg-IFN-α2b-ribavirin combination therapy and 100 age and sex matched controls. SNP in OPN at nucleotide (nt) -443 and its serum protein level were analyzed. Sustained virological response (SVR) was higher in patients with T/T at nt -443 than in those with C/C or C/T. A univariate logistic regression analysis showed that fibrosis grade, serum OPN protein level and T/T homozygotes of SNP at -443 were significant predictors for response. Receiver operating characteristics (ROC) analysis revealed the diagnostic and prognostic efficacy of serum OPN. It can be concluded that SNP in the promoter region of OPN at nt -443 and serum OPN protein level are predictors of response to the efficacy of peg-IFN-α2b-ribavirin therapy in Egyptian patients with chronic hepatitis C.

背景与目标： 骨桥蛋白 (OPN) 是由包括免疫系统在内的多种细胞产生的细胞外基质糖基磷蛋白。本研究检查了在nt -443的OPN启动子区域中的单核苷酸多态性 (SNP) 是预测聚乙二醇化干扰素 (peg-IFN-α2b)-利巴韦林联合疗法对埃及患者的治疗功效的标志物的可能性。慢性丙型肝炎。从95名接受peg-ifn-α2b-利巴韦林联合治疗并100年龄和性别匹配的慢性丙型肝炎患者中收集血液。分析了核苷酸 (nt) -443的OPN中的SNP及其血清蛋白水平。T/T在nt -443的患者的持续病毒学应答 (SVR) 高于C/C或C/T的患者。单因素logistic回归分析显示，纤维化程度，血清OPN蛋白水平和T/T SNP在-443的纯合子是缓解的重要预测指标。受试者工作特征 (ROC) 分析揭示了血清OPN的诊断和预后功效。可以得出结论，nt -443的OPN启动子区域中的SNP和血清OPN蛋白水平是埃及慢性丙型肝炎患者对peg-ifn-α2b-利巴韦林治疗疗效的预测指标。

BACKGROUND & AIMS: UNLABELLED:The study assessed contribution of genetic factors to variability of osteopontin (OPN) levels. Evidence of association of OPN levels with polymorphisms in its structural gene and integrin-binding sialoprotein gene loci was obtained. The results motivate research of OPN-related proteins and genes with respect to biomineralization and other biological processes. INTRODUCTION:OPN is a major phosphoprotein in bone, which plays key role in regulation of bone mineralization process. It is considered as a promising biomarker for osteoarthritis and osteoporosis, and various other pathological conditions. However, the contribution of genetics and other confounding factors to OPN circulating levels variation in general population has never been specifically determined. The main aims of the present study included (1) evaluation of the putative genetic and familial factors' effect on OPN variability and (2) testing the hypothesis that OPN plasma levels are associated with the genetic polymorphisms in its structural gene locus (SPP1) and in integrin-binding sialoprotein gene locus (IBSP). METHODS:To address these questions, we used a family-based sample of 925 apparently healthy Caucasian individuals. Association of OPN levels with three SNPs in each of the two selected gene loci was explored using pedigree disequilibrium tests. RESULTS:Some 58% and 13% of the OPN levels variability were attributable to genetic factors and common spouse environment, respectively. Three SNPs showed nominally significant association with OPN (p < 0.05). Of these, rs2616262 linked to IBSP promoter region remained significant after correction for multiple testing (p = 0.003). Significant association of this SNP and rs10516799 (distal segment of SPP1) with OPN was confirmed in several statistical tests. Using a special modification of variance component analysis, we examined gene-gene and gene-sex interaction effects, but found non-significant confirmation for these hypotheses. CONCLUSIONS:Further studies are required to confirm the observed results and to explore the underlying molecular and physiological mechanisms.

背景与目标：

BACKGROUND & AIMS: OBJECTIVES:Pancreatic ductal adenocarcinoma (PDAC) has a dismal 5-year survival rate of 5%. There is an urgent need for early detection while the tumors are small and surgically resectable. We assessed serum osteopontin (OPN) and tissue inhibitor of metalloproteinase 1 (TIMP-1) as possible diagnostic and prognostic biomarkers in a novel cohort of patients with pancreatic cancer. METHODS:Osteopontin and TIMP-1 levels were determined in sera from 86 patients with PDAC, 86 healthy control subjects, and 48 patients with chronic pancreatitis. Regression models were used to relate OPN and TIMP-1 to sex, age, stage, class, and treatment. Survival analyses were performed using univariate and multivariate Cox models. RESULTS:The serum levels of both OPN and TIMP-1 distinguished PDAC from chronic pancreatitis (P ≤ 0.0001) and healthy control subjects (P < 0.0001). The serum levels of both OPN and TIMP-1 also distinguished early-stage resectable PDAC cases from chronic pancreatitis (P < 0.04) and healthy control subjects (P < 0.01). High serum levels of OPN were significantly correlated with reduced patient survival. CONCLUSIONS:Serum OPN and TIMP-1 have use as diagnostic biomarkers in PDAC. Our data suggest a potential benefit of using OPN, TIMP-1, and CA 19-9 in a panel to improve diagnostic accuracy in PDAC.

背景与目标：

BACKGROUND & AIMS: :Osteopontin (OPN) is expressed in various human cancers and associated with tumor progression, invasion and metastasis in many manners. The purpose of this study is to investigate the clinical significance of OPN expression in metastatic lesions of ovarian cancers, since the prognosis of the patients with peritoneal dissemination is extremely poor. In primary tumors and peritoneal metastatic lesions from 40 patients with stage III ovarian cancers, the protein levels of OPN and histoscores were determined by enzyme immunoassay and immunohistochemistry, respectively. Immunohistochemical staining revealed OPN was distributed in the cytoplasm and nuclear compartments of the cancer and stromal cells within and around the tumor. The OPN level was significantly (p < 0.05) increased in 32 of 40 metastatic lesions of ovarian cancers. The OPN increased cases identified by immunohistochemical staining were consistent with those identified by the sandwich immunoassay. The prognosis of the 32 patients with significant increase of OPN in ovarian cancers was extremely poor, whereas the 36-month survival rate of the 8 patients with no increase of OPN was 75%. Multivariate analysis revealed that the levels of OPN were independent predictors of prognosis from clinical characteristics (age, lesion size, histological types). OPN might be associated with peritoneal metastasis and its advancement, and that the OPN level in metastatic lesion may be a prognostic indicator in ovarian cancers.

背景与目标： : 骨桥蛋白 (OPN) 在各种人类癌症中表达，并以多种方式与肿瘤的进展，侵袭和转移有关。这项研究的目的是探讨OPN表达在卵巢癌转移灶中的临床意义，因为腹膜播散患者的预后极差。在40例III期卵巢癌患者的原发性肿瘤和腹膜转移性病变中，分别通过酶免疫法和免疫组织化学测定OPN和组织学核心的蛋白水平。免疫组织化学染色显示OPN分布在癌症的细胞质和核区室以及肿瘤内和周围的基质细胞中。40个卵巢癌转移灶中有32个OPN水平显着升高 (p <0.05)。通过免疫组织化学染色鉴定的OPN增加的病例与通过三明治免疫分析法鉴定的病例一致。32例卵巢癌中OPN显著增加的患者的预后极差，而8例OPN未增加的患者的36个月生存率为75%。多因素分析显示，OPN水平是临床特征 (年龄，病变大小，组织学类型) 预后的独立预测因素。OPN可能与腹膜转移及其进展有关，转移性病变中的OPN水平可能是卵巢癌的预后指标。

BACKGROUND & AIMS: BACKGROUNDS AND AIMS:Cardiovascular calcification is an important cause of morbidity and mortality in hemodialysis (HD) patients. Vascular and valvular calcification are indicators of increased tissue calcification. The relationship of osteopontin (OPN) - which is known as a vascular calcification inhibitor - and fibroblast growth factor-23 (FGF-23) - which its related to vascular calcification, as recently shown - to valvular calcification is unknown. In this cross-sectional study, we examined the relationship between heart valve calcification, serum OPN, and FGF-23 levels. MATERIALS AND METHODS:85 adults who were on HD treatment for at least 6 months were included in the study. Echocardiographic evaluation was made with the General Electric echocardiography device and the same cardiologist. FGF-23 and osteopontin levels were measured by ELISA. RESULTS:54% of our patients were male, mean age was 49.8 ± 15.1 years, and mean HD duration was 52.5 ± 39.6 months. 34% of the patients were diabetic, and 17.6% had a history of coronary artery disease. 1.25 mmol/L calcium were used as dialysate calcium in 84.7% of the patients. 60% of the patients were on vitamin D replacement therapy, and 7.1% were receiving cinacalcet treatment. Valvular calcification ratio of the patients was 44%. Mean FGF-23 level was 682 ± 771.7 pg/mL, and mean OPN level was 22.2 ± 8.2 ng/mL. When the patients with and without heart valve calcification were compared, the group with heart valve calcification was older and had lower serum OPN levels. There were differences between the groups on left atrial diameters, left ventricular end-diastolic diameters, and posterior-wall thicknesses. In the logistic regression analysis, it was seen that age and serum OPN levels were predictors of valvular calcification. CONCLUSION:Serum osteopontin level is associated with heart valve calcification in HD patients, but there was no relationship found with FGF-23. Further research is needed on the subject.
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背景与目标：

BACKGROUND & AIMS: :Homeostasis of cholesterol is regulated by absorption in the intestine and synthesis in the liver. The authors previously demonstrated that OPN (osteopontin) exhibits the ability to alter hepatic cholesterol metabolism, thus affecting cholesterol gallstone formation in mice. The present study investigated the role of OPN in cholesterol gallstone formation, focusing on its effect on intestinal absorption of cholesterol. OPN gene knockout (OPN‑/‑) mice and wild‑type mice were respectively fed with a chow or lithogenic diet (LD) for 8 weeks. Following an 8‑week LD period, the incidence of gallstone, bile composition, level of serum and fecal lipids and the expression of intestinal associated genes were analyzed. OPN‑/‑ mice were protected from gallstone formation induced by 8 weeks' LD‑feeding. This protective effect from OPN deficiency was associated with alterations in bile composition, including a reduced concentration of biliary cholesterol. Additionally, plasma cholesterol level was decreased in LD‑fed OPN‑/‑ mice. The alterations primarily resulted from the decreased expression of intestinal Niemann‑Pick C1‑like (NPC1 L) 1, which is important in the intestinal absorption of cholesterol. The present study demonstrated that OPN deficiency reduced intestinal absorption of cholesterol by suppressing the expression of NPC1L1, thus protecting mice from cholesterol gallstone formation.

背景与目标： : 胆固醇的稳态受肠道吸收和肝脏合成的调节。作者先前证明OPN (骨桥蛋白) 表现出改变肝胆固醇代谢的能力，从而影响小鼠胆固醇胆结石的形成。本研究调查了OPN在胆固醇结石形成中的作用，重点是其对胆固醇肠道吸收的影响。OPN基因敲除 (OPN ‑/‑) 小鼠和野生型小鼠分别饲喂chow或成石饮食 (LD) 8周。在为期8周的LD期后，分析了胆结石的发生率，胆汁成分，血清和粪便脂质水平以及肠道相关基因的表达。Opn-/-小鼠免受8周的ld-feeding诱导的胆结石形成的影响。OPN缺乏症的这种保护作用与胆汁成分的改变有关，包括降低胆汁胆固醇的浓度。此外，ld-fed opn-/-小鼠的血浆胆固醇水平降低。这些改变主要是由于肠neemann-pick C1样 (NPC1 L) 1的表达降低，这在胆固醇的肠道吸收中很重要。本研究表明，OPN缺乏通过抑制NPC1L1的表达来减少肠道对胆固醇的吸收，从而保护小鼠免受胆固醇结石的形成。

BACKGROUND & AIMS: :Osteopontin (OPN) expression is reduced in surviving dopaminergic neurones in the substantia nigra (SN) in Parkinson's disease (PD), and protects against MPP(+) -induced cell death in primary mesencephalic cultures and 6-OHDA-induced cell loss in the rat, while inactivation of OPN aggravates cell death. OPN is thought to act through interactions with integrin receptors or CD44. However, the specific protein interactions involved in OPN-mediated neuroprotection are unknown and are the focus of this study. The yeast two-hybrid (YTH) technique was utilised to investigate OPN-protein interactions, using full-length human OPN to screen a human foetal brain cDNA library. Proteins involved in apoptosis, protein degradation and microtubule stability were identified as OPN binding partners. These included: MAP1A and MAP1B, which regulate microtubule stability; RNF138, an E3 ubiquitin-ligase; proteasome β1 subunit, a subunit of the 20S proteasome involved in the ubiquitin-dependent cleavage of peptides; BAG6, SGTΑ and EF1A, proteins implicated in control of apoptosis; DnaJB1, a co-chaperone of Hsp70s; and pleiotrophin, a growth factor. The use of site-directed mutagenesis to modify known OPN protein binding sites outside the RGD integrin binding domain, specifically Y165A and D139E, inhibited some of these interactions. Further investigation using affinity pull-down assays, co-immunoprecipitation and immunohistochemistry confirmed that OPN associates with MAP1A and MAP1B in rat SN and striatum. These findings indicate a role for OPN in the regulation of microtubule dynamics, apoptosis and proteolysis in the brain, suggesting that OPN may act as an endogenous multifunctional protective protein in PD.

背景与目标： ：在帕金森病（PD）的黑质（SN）中幸存的多巴胺能神经元中，骨桥蛋白（OPN）的表达减少，并防止MPP（）诱导的原发性中脑培养物中的细胞死亡和6-OHDA诱导的中性粒细胞丢失大鼠，而OPN失活会加剧细胞死亡。 OPN被认为是通过与整联蛋白受体或CD44相互作用来发挥作用的。但是，参与OPN介导的神经保护的特定蛋白质相互作用尚不清楚，并且是本研究的重点。酵母双杂交（YTH）技术用于研究OPN-蛋白相互作用，使用全长人OPN筛选人胎脑cDNA文库。参与凋亡，蛋白质降解和微管稳定性的蛋白质被鉴定为OPN结合伴侣。其中包括：MAP1A和MAP1B，它们调节微管的稳定性； RNF138，E3泛素连接酶；蛋白酶体β1亚基，是20S蛋白酶体的一个亚基，参与泛素依赖性肽的裂解。 BAG6，SGTAA和EF1A蛋白与细胞凋亡的控制有关； DnaJB1，Hsp70s的伴侣分子。以及促生长素-促生长素。使用定点诱变来修饰RGD整联蛋白结合域之外的已知OPN蛋白结合位点，特别是Y165A和D139E，抑制了其中某些相互作用。使用亲和力下拉测定，免疫共沉淀和免疫组织化学的进一步研究证实，OPN与大鼠SN和纹状体中的MAP1A和MAP1B缔合。这些发现表明OPN在调节脑中微管动力学，凋亡和蛋白水解中的作用，表明OPN可能是PD中的内源性多功能保护蛋白。

BACKGROUND & AIMS: :Uranium is the heaviest natural element, mainly found in aqueous medium as the hexavalent uranyl ion (UO22+). Bones are the main organs in which uranium accumulates, depending on as yet unknown molecular and cellular mechanisms. Recently, it has been revealed that osteopontin (OPN), a protein involved in bio-mineralization processes, and its main naturally occurring cleaved form (fOPN), have nanomolar affinities for UO22+. The binding of UO22+ is due to both the phosphorylation sites and acidic residues of these proteins and is accompanied by a slight gain in secondary structure. OPN is an Intrinsically Disordered Protein (IDP), a family of proteins which play a crucial role in several interaction networks, where phosphorylations are thought to be key elements. OPN has been shown to bind lactoferrin (LF) and the two proteins have antagonist functions in the modulation of the bio-mineralization process. However, to date, there has been no evidence that UO22+ and LF compete in their binding to OPN or not. Based on a series of convergent experimental data, this study first addressed in detail the LF/fOPN interaction and proposed a LF:fOPN 4/1 maximal stoichiometry. Moreover the phosphorylations were demonstrated to be necessary for the stability of such complexes. The interaction of preformed UO22+/fOPN complexes with LF was also investigated and the occurrence of several entities involving the three partners was demonstrated. These complexes did not reveal any significant conformational changes compared to those obtained in the absence of UO22+. The results have shown not only that LF and UO22+ do not compete, but also that these complexes are likely to be more stable than LF/fOPN complexes, as indicated by their melting temperature (Tm) values. The potential impact of those uranyl-stabilized ternary complexes on some biological pathways now remains to be assessed. Nonetheless, this work has contributed to shedding light on the formation of stable ternary complexes involving a large structured protein, an IDP and an exogenous metal.

背景与目标： : 铀是最重的天然元素，主要以六价铀酰离子 (UO22) 存在于水性介质中。骨骼是铀积累的主要器官，这取决于尚不为人所知的分子和细胞机制。最近，已经发现骨桥蛋白 (OPN) 是一种参与生物矿化过程的蛋白质，其主要的天然裂解形式 (fOPN) 对UO22具有纳摩尔亲和力。UO22的结合归因于这些蛋白质的磷酸化位点和酸性残基，并伴随着二级结构的轻微增加。OPN是一种内在无序的蛋白质 (IDP)，是一个蛋白质家族，在几个相互作用网络中起着至关重要的作用，其中磷酸化被认为是关键元素。OPN已被证明与乳铁蛋白 (LF) 结合，并且这两种蛋白质在调节生物矿化过程中具有拮抗功能。然而，到目前为止，还没有证据表明UO22 + 和LF在与OPN的结合上是否竞争。基于一系列收敛的实验数据，本研究首先详细讨论了LF/fOPN相互作用，并提出了LF:fOPN 4/1最大化学计量。此外，已证明磷酸化对于此类配合物的稳定性是必需的。还研究了预制的UO22/fOPN复合物与LF的相互作用，并证明了涉及三个伙伴的几个实体的发生。与在没有UO22的情况下获得的配合物相比，这些配合物没有显示出任何明显的构象变化。结果不仅表明LF和UO22不竞争，而且这些配合物可能比LF/fOPN配合物更稳定，如它们的熔融温度 (Tm) 值所示。这些铀酰稳定的三元复合物对某些生物途径的潜在影响现在仍有待评估。尽管如此，这项工作有助于阐明涉及大型结构化蛋白质，IDP和外源金属的稳定三元复合物的形成。

BACKGROUND & AIMS: :The avian eggshell primarily consists of calcium carbonate mineral (calcite) and matrix proteins. Here we review matrix-mineral relationships in the eggshell at the ultrastructural level using scanning and transmission electron microscopy, and describe the distribution of osteopontin (OPN) as determined by colloidal gold immunolabeling for OPN. A rich protein network integrated within the calcitic structure of the eggshell shows variable, region-specific organization that included layered fibrous planar sheets of matrix, thin filamentous threads, thin film-like surface coatings, vesicular structures and isolated proteins residing on cleaved {104} crystallographic faces of the eggshell calcite. Except for the vesicular structures, these matrix structures all immunolabeled strongly for OPN. Given the potent mineralization- inhibiting function of OPN, we discuss how this protein might regulate eggshell growth rate and inhibit calcification at specific compartmental boundaries to provide eggshell form.

背景与目标： : 禽类蛋壳主要由碳酸钙矿物 (方解石) 和基质蛋白组成。在这里，我们使用扫描和透射电子显微镜在超微结构水平上回顾了蛋壳中的基质-矿物质关系，并描述了通过胶体金免疫标记对OPN确定的骨桥蛋白 (OPN) 的分布。整合在蛋壳的钙化结构中的丰富的蛋白质网络显示出可变的，区域特定的组织，其包括基质的层状纤维平面片材，细丝状线，薄膜状表面涂层，囊泡结构和驻留在蛋壳方解石的裂开的 {104} 晶体学面上的分离的蛋白质。除囊泡结构外，这些基质结构均对OPN进行了强烈的免疫标记。鉴于OPN具有有效的矿化抑制功能，我们讨论了该蛋白如何调节蛋壳生长速率并抑制特定隔室边界的钙化以提供蛋壳形式。

BACKGROUND & AIMS: :Our aim was to elucidate whether osteopontin (OPN) is involved in the onset of mineralisation and progression of extracellular calcification in striatal lesions due to mitochondrial toxin 3-nitropropionic acid exposure. OPN expression had two different patterns when observed using light microscopy. It was either localised to the Golgi complex in brain macrophages or had a small granular pattern scattered in the affected striatum. OPN labelling tended to increase in number and size over a 2-week period following the lesion. Ultrastructural investigations revealed that OPN is initially localised to degenerating mitochondria within distal dendrites, which were then progressively surrounded by profuse OPN on days 7-14. Electron probe microanalysis of OPN-positive and calcium-fixated neurites indicated that OPN accumulates selectively on the surfaces of degenerating calcifying dendrites, possibly via interactions between OPN and calcium. In addition, 3-dimensional reconstruction of OPN-positive neurites revealed that they are in direct contact with larger OPN-negative degenerating dendrites rather than with fragmented cell debris. Our overall results indicate that OPN expression is likely to correlate with the spatiotemporal progression of calcification in the affected striatum, and raise the possibility that OPN may play an important role in the initiation and progression of microcalcification in response to brain insults.

背景与目标： : 我们的目的是阐明骨桥蛋白 (OPN) 是否因线粒体毒素3-硝基丙酸暴露而参与纹状体病变的矿化和细胞外钙化的发生。使用光学显微镜观察时，OPN表达有两种不同的模式。它要么位于脑巨噬细胞中的高尔基体上，要么在受影响的纹状体中散布有小的颗粒图案。病变后的2周内，OPN标记的数量和大小趋于增加。超微结构研究表明，OPN最初位于远端树突内退化的线粒体，然后在第7-14天逐渐被大量OPN包围。OPN阳性和钙固定的神经突的电子探针显微分析表明，OPN可能通过OPN和钙之间的相互作用选择性地积聚在退化的钙化树突的表面上。此外，OPN阳性神经突的3维重建显示，它们与较大的OPN阴性退化树突直接接触，而不是与破碎的细胞碎片直接接触。我们的总体结果表明，OPN的表达可能与受影响的纹状体中钙化的时空进展相关，并增加了OPN可能在响应脑损伤的微钙化的启动和进展中起重要作用的可能性。