High-Affinity Binding of LDL Receptor-Related Protein 1 to Matrix Metalloprotease 1 Requires Protease:Inhibitor Complex Formation.

Matrix metalloprotease (MMP) activation contributes to the degradation of the extracellular matrix (ECM), resulting in a multitude of pathologies. Low-density lipoprotein receptor-related protein 1 (LRP1) is a multifaceted endocytic and signaling receptor that is responsible for internalization and lysosomal degradation of diverse proteases, protease inhibitors, and lipoproteins along with numerous other proteins. In this study, we identified MMP-1 as a novel LRP1 ligand. Binding studies employing surface plasmon resonance revealed that both proMMP-1 and active MMP-1 bind to purified LRP1 with equilibrium dissociation constants (KD) of 19 and 25 nM, respectively. We observed that human aortic smooth muscle cells readily internalize and degrade 125I-labeled proMMP-1 in an LRP1-mediated process. Our binding data also revealed that all tissue inhibitors of metalloproteases (TIMPs) bind to LRP1 with KD values ranging from 23 to 33 nM. Interestingly, the MMP-1/TIMP-1 complex bound to LRP1 with an affinity (KD = 0.6 nM) that was 30-fold higher than that of either component alone, revealing that LRP1 prefers the protease:inhibitor complex as a ligand. Of note, modification of lysine residues on either proMMP-1 or TIMP-1 ablated the ability of the MMP-1/TIMP-1 complex to bind to LRP1. LRP1's preferential binding to enzyme:inhibitor complexes was further supported by the higher binding affinity for proMMP-9/TIMP-1 complexes than for either of these two components alone. LRP1 has four clusters of ligand-binding repeats, and MMP-1, TIMP-1, and MMP-1/TIMP-1 complexes bound to cluster III most avidly. Our results reveal an important role for LRP1 in controlling ECM homeostasis by regulating MMP-1 and MMP-9 levels.

ISA-TAB-Nano: a specification for sharing nanomaterial research data in spreadsheet-based format.

BACKGROUND AND MOTIVATION: The high-throughput genomics communities have been successfully using standardized spreadsheet-based formats to capture and share data within labs and among public repositories. The nanomedicine community has yet to adopt similar standards to share the diverse and multi-dimensional types of data (including metadata) pertaining to the description and characterization of nanomaterials. Owing to the lack of standardization in representing and sharing nanomaterial data, most of the data currently shared via publications and data resources are incomplete, poorly-integrated, and not suitable for meaningful interpretation and re-use of the data. Specifically, in its current state, data cannot be effectively utilized for the development of predictive models that will inform the rational design of nanomaterials. RESULTS: We have developed a specification called ISA-TAB-Nano, which comprises four spreadsheet-based file formats for representing and integrating various types of nanomaterial data. Three file formats (Investigation, Study, and Assay files) have been adapted from the established ISA-TAB specification; while the Material file format was developed de novo to more readily describe the complexity of nanomaterials and associated small molecules. In this paper, we have discussed the main features of each file format and how to use them for sharing nanomaterial descriptions and assay metadata. CONCLUSION: The ISA-TAB-Nano file formats provide a general and flexible framework to record and integrate nanomaterial descriptions, assay data (metadata and endpoint measurements) and protocol information. Like ISA-TAB, ISA-TAB-Nano supports the use of ontology terms to promote standardized descriptions and to facilitate search and integration of the data. The ISA-TAB-Nano specification has been submitted as an ASTM work item to obtain community feedback and to provide a nanotechnology data-sharing standard for public development and adoption.

The NCI Thesaurus quality assurance life cycle.

The National Cancer Institute Enterprise Vocabulary Services (NCI EVS) uses a wide range of quality assurance (QA) techniques to maintain and extend NCI Thesaurus (NCIt). NCIt is a reference terminology and biomedical ontology used in a growing number of NCI and other systems that extend from translational and basic research through clinical care to public information and administrative activities. Both automated and manual QA techniques are employed throughout the editing and publication cycle, which includes inserting and editing NCIt in NCI Metathesaurus. NCI EVS conducts its own additional periodic and ongoing content QA. External reviews, and extensive evaluation by and interaction with EVS partners and other users, have also played an important part in the QA process. There have always been tensions and compromises between meeting the needs of dependent systems and providing consistent and well-structured content; external QA and feedback have been important in identifying and addressing such issues. Currently, NCI EVS is exploring new approaches to broaden external participation in the terminology development and QA process.

Proangiogenic role of neutrophil-like inflammatory heterophils during neovascularization induced by growth factors and human tumor cells.

A quantitative in vivo angiogenesis model employing collagen onplants placed on the chick embryo chorioallantoic membrane (CAM) has been used in this study to assess the spatial and temporal associations between neutrophil-like inflammatory cells, namely chicken heterophils, and the development of new blood vessels. Previously we have demonstrated that monocytes/macrophages infiltrating the onplants were associated with extracellular matrix remodeling and angiogenesis, in particular by delivering MMP-13 collagenase. By introducing chicken gelatinase B (chMMP-9) as a specific marker for heterophils, we now show that the onset and extent of angiogenesis induced by purified growth factors or by human HT-1080 fibrosarcoma cells correlated with the initial influx of chMMP-9-positive heterophils. This early heterophil arrival was followed by the infiltration of monocytes/macrophages and appeared to sustain further blood vessel formation. The disruption of inflammatory cell influx by 2 mechanistically distinct anti-inflammatory drugs, cortisone and ibuprofen, significantly inhibited angiogenesis, indicating a functional involvement of these inflammatory cells in new blood vessel development. A direct addition of isolated heterophils or purified chMMP-9 into the HT-1080 onplants engrafted into cortisone- or ibuprofen-treated embryos reversed the antiangiogenic effects of the drugs. The exogenously added heterophils induced in vivo a further infiltration of endogenous heterophils and monocytes and dramatically rescued the impaired angiogenesis, highlighting the importance of early inflammatory leukocytes in tumor-induced angiogenesis. Moreover, purified heterophils incorporated into onplants lacking growth factors or tumor cells induced angiogenesis in nontreated embryos, further indicating a direct proangiogenic role for neutrophil-like leukocytes.

The low density lipoprotein receptor-related protein LRP is regulated by membrane type-1 matrix metalloproteinase (MT1-MMP) proteolysis in malignant cells.

We demonstrate that the presentation of LRP and the subsequent uptake of its ligands by malignant cells are both strongly regulated by MT1-MMP. Because LRP is essential for the clearance of multiple ligands, these findings have important implications for many pathophysiological processes including the pericellular proteolysis in neoplastic cells as well as the fate of the soluble matrix-degrading proteases such as MMP-2. MT1-MMP is a key protease in cell invasion and a physiological activator of MMP-2. Cellular LRP consists of a non-covalently associated 515-kDa extracellular alpha-chain (LRP-515) and an 85-kDa membrane-spanning beta-chain, and plays a dual role as a multifunctional endocytic receptor and a signaling molecule. Through the capture and uptake of several soluble proteases, LRP is involved in the regulation of matrix proteolysis. LRP-515 associates with the MT1-MMP catalytic domain and is highly susceptible to MT1-MMP proteolysis in vitro. Similar to MT1-MMP, the metalloproteinases MT2-MMP, MT3-MMP and MT4-MMP also degrade LRP. The N-terminal and C-terminal parts of the LRP-515 subunit are resistant and susceptible, respectively, to MT1-MMP proteolysis. In cells co-expressing LRP and MT1-MMP, the proteolytically competent protease decreases the levels of cellular LRP and releases its N-terminal portion in the extracellular milieu while the catalytically inert protease co-precipitates with LRP. These events implicate MT1-MMP, not only in the activation of MMP-2, but also in the mechanisms that control the subsequent fate of MMP-2 in cells and tissues.