Age-dependent increase of discoidin domain receptor 2 and matrix metalloproteinase 13 expression in temporomandibular joint cartilage of type IX and type XI collagen-deficient mice.
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Our previous studies demonstrated that mutations in type IX and type XI collagens in mice caused osteoarthritis (OA)-like changes in knee and temporomandibular (TM) joints. We also found that the overexpression of matrix metalloproteinase 13 (Mmp-13) was probably due to the up-regulation of a collagen receptor, discoidin domain receptor 2 (Ddr2), which was responsible for knee cartilage degeneration in mutant mice. The objective of our study was to determine whether the expression of Mmp-3, Mmp-13 and Ddr2 was increased in OA-like TM joints in mutant mice using immunohistochemistry. We found that the staining for Ddr2, Mmp-13 and Mmp-derived type II collagen fragments in tissue sections from 6-month-old mice was increased in TM joints of the mutant mice. In contrast, we found no difference in the staining for Mmp-3 amongst the two mutant mice and their wild-type littermates. We conclude that, similar to previous observations in knee joints, the overexpression of Ddr2 and Mmp-13 may be responsible for the OA-like change in TM joints in mutant mice. (+info)
Expression, purification, and refolding of recombinant collagen alpha1(XI) amino terminal domain splice variants.
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The amino terminal domain of collagen type XI alpha1 chain is a noncollagenous structure that is essential for the regulation of fibrillogenesis in developing cartilage. The amino terminal domain is alternatively spliced at the mRNA level, resulting in proteins expressed as splice variants. These splice variants, or isoforms, have unique distribution in growing tissues, alluding to distinct roles in development. We report here a rapid and straightforward method for expression, purification and in vitro folding of recombinant collagen XI isoforms alpha1(XI) NTD[p7] and alpha1(XI) NTD[p6b+7]. The recombinant isoforms were expressed in Escherichia coli as bacterial inclusion bodies. Unfolded carboxy terminal polyhistidine tagged proteins were purified via nickel affinity chromatography and refolded with specific protocols optimized for each isoform. Purity was assessed by SDS-PAGE and correct secondary structure by a comparison of circular dichroism data with that obtained for Npp. Protein expression and purification of the recombinant collagen XI splice variants will allow further studies to elucidate the structure and molecular interactions with components of the extracellular matrix. This research will clarify the mechanism of collagen XI mediated regulation of collagen fibrillogenesis. (+info)
Unique matrix structure in the rough endoplasmic reticulum cisternae of pseudoachondroplasia chondrocytes.
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Mutations in cartilage oligomeric matrix protein (COMP) cause two skeletal dysplasias, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED/EDM1). Because COMP exists as a homopentamer, only one mutant COMP subunit may result in an abnormal complex that is accumulated in expanded rough endoplasmic reticulum (rER) cisternae, a hallmark of PSACH. Type IX collagen and matrilin-3 (MATN3), also accumulate in the rER cisternae of PSACH chondrocytes, but it is unknown how mutant COMP interacts with these proteins. The studies herein focus on defining the organization of these intracellularly retained proteins using fluorescence deconvolution microscopy. A unique matrix organization was identified in which type II procollagen formed a central core surrounded by a protein network of mutant COMP, type IX collagen, and MATN3. This pattern of matrix organization was found in multiple cisternae from single chondrocytes and in chondrocytes with different COMP mutations, indicating a common pattern of interaction. This suggests that stalling of mutant COMP and an interaction between mutant COMP and type II procollagen are initiating events in the assembly of matrix in the rER, possibly explaining why the material is not readily cleared from the rER. Altogether, these data suggest that mutant COMP initiates and perhaps catalyzes premature intracellular matrix assembly. (+info)
Surfactin from Bacillus subtilis displays anti-proliferative effect via apoptosis induction, cell cycle arrest and survival signaling suppression.
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The effect of surfactin on the proliferation of LoVo cells, a human colon carcinoma cell line, was examined. Surfactin strongly blocked the proliferation of LoVo cells by inducing pro-apoptotic activity and arresting the cell cycle, according to several lines of evidence on DNA fragmentation, Annexin V staining, and altered levels of poly (ADP-ribose) polymerase, caspase-3, p21(WAF1/Cip1), p53, CDK2 and cyclin E. The anti-proliferative activity of surfactin was mediated by inhibiting extracellular-related protein kinase and phosphoinositide 3-kinase/Akt activation, as assessed by phosphorylation levels. Therefore, our data suggest that surfactin may have anti-cancer properties as a result of its ability to downregulate the cell cycle and suppress its survival. (+info)
Glyceryl trinitrate inhibits hypoxia/reoxygenation-induced apoptosis in the syncytiotrophoblast of the human placenta: therapeutic implications for preeclampsia.
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Damage of the placenta resulting from ischemia-reperfusion is important to the pathophysiology of preeclampsia. Here we investigated whether low concentrations of glyceryl trinitrate (GTN), a nitric oxide mimetic with anti-apoptotic properties, inhibit hypoxia/reoxygenation-induced apoptosis in the syncytiotrophoblast of chorionic villous explants from human placentas. Compared with villi analyzed immediately after delivery or maintained under normoxic conditions, villi exposed to a 6-hour cycle of hypoxia/reoxygenation exhibited greater numbers of syncytiotrophoblasts with terminal dUTP nick-end labeling (TUNEL)-positive nuclei in the syncytiotrophoblast. This increased number of TUNEL-positive nuclei was paralleled by higher levels of 4-hydroxynonenal (marker of lipid peroxidation), nitrotyrosine residues, and active caspase-3 and polyADP-ribose polymerase expression. Morphological analysis of explants exposed to hypoxia/reoxygenation revealed apoptotic and aponecrotic features similar to those of chorionic villi from preeclamptic pregnancies. Treatment with GTN during the hy-poxia/reoxygenation cycle blocked the increases in the number of TUNEL-positive nuclei and in the levels of 4-hydroxynonenal, nitrotyrosine, and active caspase-3. Incubation with GTN also attenuated the hypoxia/reoxygenation-induced polyADP-ribose polymerase expression and the apoptotic and aponecrotic morphological alterations. These results suggest that small concentrations of nitric oxide protect chorionic villi from hypoxia/reoxygenation-induced damage and provide a rationale for the use of low doses of nitric oxide mimetics in the treatment and/or prevention of preeclampsia. (+info)
Tumor vascular proteins as biomarkers in ovarian cancer.
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PURPOSE: This study aimed to identify novel ovarian cancer biomarkers and potential therapeutic targets through molecular analysis of tumor vascular cells. METHODS: Immunohistochemistry-guided laser-capture microdissection and genome-wide transcriptional profiling were used to identify genes that were differentially expressed between vascular cells from human epithelial ovarian cancer and healthy ovaries. Tumor vascular markers (TVMs) were validated through quantitative real-time polymerase chain reaction (qRT-PCR) of immunopurified tumor endothelial cells, in situ hybridization, immunohistochemistry, and Western blot analysis. TVM expression in tumors and noncancerous tissues was assessed by qRT-PCR and was profiled using gene expression data. RESULTS: We identified a tumor vascular cell profile of ovarian cancer that was distinct from the vascular profile of normal ovary and other tumors. We validated 12 novel ovarian TVMs. These were expressed by immunopurified tumor endothelial cells and localized to tumor vasculature. Select TVMs were found to be specifically expressed in ovarian cancer and were absent in all normal tissues tested, including female reproductive tissues with physiologic angiogenesis. Many ovarian TVMs were expressed by a variety of other solid tumors. Finally, overexpression of any one of three ovarian TVMs by vascular cells was associated with decreased disease-free interval (all P < .005). CONCLUSION: We have identified for the first time the molecular profile of ovarian tumor vasculature. We demonstrate that TVMs may serve as potential biomarkers and molecular targets for ovarian cancer and a variety of other solid tumors. (+info)
Apoptosis assays with lymphoma cell lines: problems and pitfalls.
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Much attention has been focused on the manner in which tumour cells die after treatment with cytotoxic agents. The basic question is whether cells die via apoptosis or via direct damage from the toxic agent. Various assays have been used to make this distinction. However, we show herein that some of the widely used assays for apoptosis do not in fact distinguish between apoptosis and other forms of cell death. More specifically: (1) A sub-G1 DNA content, identified by propidium iodide staining, does not distinguish between apoptotic and necrotic cells; (2) loss of mitochondrial membrane potential does not distinguish between apoptotic and necrotic cells, unless combined with an assay for an intact cell membrane; (3) subcellular fragments that arise from dead cells or from apoptotic bodies can interfere with some assays for apoptosis such as annexin V staining, as they may be close to the size of intact cells, making it difficult to decide where to set the size threshold; (4) irradiated cells display a large increase in nonspecific Ab binding. This may be partly due to an increase in cell size, but, regardless of the cause, it can lead to a mistaken conclusion that there is an increase in a particular antigen if appropriate control reagents are not tested; and (5) experiments utilising Ab crosslinking have neglected the role of cell aggregation, which can cause multiple problems including death from mechanical stress when cells are handled. Consideration of these factors will improve our ability to determine the mode of cell death. (+info)
Differential onset of apoptosis in influenza A virus H5N1- and H1N1-infected human blood macrophages.
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Pathogenesis of the highly pathogenic avian influenza virus A/Hong Kong/483/97 (H5N1/97) remains to be investigated. It was demonstrated recently that H5N1 dysregulation of proinflammatory cytokines in human macrophages is a p38-kinase-dependent process. The results indicated that macrophages may play a role in disease severity. To investigate cellular responses to H5N1 infection further, apoptosis and its related pathways were studied in primary blood macrophages. Here, it is shown that the H5N1/97 virus triggered apoptosis, including caspases and PARP activation, in infected macrophages with a delayed onset compared with H1N1 counterparts. Similar results were also found in human macrophages infected by precursors of the H5N1/97 virus. Thus, these results showed that the delay in apoptosis onset in macrophages infected by H5N1/97 and its related precursor subtypes may be a means for the pathogens to have longer survival in the cells; this may contribute to the pathogenesis of H5N1 disease in humans. (+info)