Matrix metalloproteinase (MMP) induced extra cellular matrix (ECM) degradation is a crucial process involved in the development of many chronic inflammatory diseases, including cardiac remodeling and cancer metastasis. In cardiac remodeling, the presence of pathological stimuli leads to elevated MMP-9 expression and impairment of cardiac performance, which subsequently develops into heart failure. While in tumorgenesis, MMP-9 has been found to play key roles in metastasis, as it can break physical barriers for the tumor. Therefore, searching for agents targeting MMP-9 is a new direction for the treatment of cardiac remodeling and cancer metastasis. Chinese herbal medicine is becoming increasingly used worldwide in recent decades. In the past twenty years, as many highly selective and sensitive bioassays were introduced into the bioactive compounds screening from herbal medicine, more than one hundred new drug candidates have been identified. Therefore, herbal medicine is a potential source of bioactive compounds. Panax notoginseng (PNG) is one of the most common traditional Chinese medicines to treat cardiovascular diseases, and it was also reported to have anti-cancer effect. We hypothesized that it contains bioactive compounds that could inhibit MMP-9 activity in cardiomyocytes and cancer cells. In order to examine the effect of PNG on cardiac remodeling and cancer metastasis, we employed TNF-α induced MMP-9 in H9c2 cell (a rat cardiomyocyte) and HepG-2 cell (a human hepatoma cell) as an in vitro assay, respectively. PNG was first extracted by four different extraction methods according to the polarity of the solvent. The most effective fraction in suppressing MMP-9 activity in TNF-α induced H9c2 cell was chosen for further separation by silica gel column chromatography and high performance liquid chromatography (HPLC) until a single compound was isolated. According to the result of spectroscopic analysis by NMR, the compound was identified as ginsenoside Rb1. For the bioactivity assays, real-time quantitative polymerase chain reaction (QPCR) and Enzyme-linked immunosorbent assay (ELISA) were used to measure the mRNA and protein expression of MMP-9, respectively. We also examined the MMP-9 activity by gelatin zymography. The results showed that both of the PNG extract obtained from 10% ethanol extraction method (PNG-3) and purified Compound P (ginsenoside Rb1) showed significant inhibitory effect on MMP-9 expression and activity in H9c2 cells and HepG-2 cells. We further examined the molecular mechanisms of the inhibitory effect of PNG-3. H9c2 and HepG-2 cells were pretreated with different kinase inhibitors followed by the activation by TNF-α. The results showed the protein kinase R (PKR) inhibitor could inhibit TNF-α induced MMP-9 in both of the two cell lines. Furthermore, the results of Western blot showed the PNG-3 suppressed the phosphorylation of eIF-2α which is a down-stream effector of PKR in TNF-α stimulated H9c2 and HepG-2 cells, respectively. Therefore, PNG-3 may act through PKR to regulate TNF-α induced MMP-9 activity. In summary, bioactivity guided fractionation is an effective way of isolating bioactive compounds from medicinal herbs. In addition, PNG containing ginsenoside Rb1 may be a potential candidate of MMP-9 inhibition for the treatment of cardiac remodeling and cancer metastasis. / published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

The extracellular matrix (ECM) is the material found surrounding the cells in a tissue. One component of the ECM is the elastic fiber, which confers the property of elasticity to its environment. Organs such as the lung, skin and major blood vessels have an abundance of elastic fibers so that they are able to expand and recoil. Elastic fibers are composed of two main components; elastin and microfibrils. Microfibrils are composed primarily of fibrillin-1 and provide a scaffold unto which tropoelastin monomers assemble. Elastic fibers interact with many other proteins in the ECM, one of which is fibulin-5. Based on the severe elastic fiber defects observed in the fibulin-5 null mouse, it was established that fibulin-5 plays an essential role in elastic fiber development. This role may be in the deposition of tropoelastin onto microfibrils and/or in stabilizing the elastic fibers in the extracellular matrix. In the present study, the relationship between fibulin-5 and the elastic fiber was investigated through a number of in vivo and in vitro experiments. To test the hypothesis that fibulin-5 requires the presence of elastin to assemble in the ECM, full-length recombinant fibulin-5 (rF5) was purified from transfected cells and used to make a fibulin-5 antibody. Solid-phase binding assays using rF5 showed that fibulin-5 binds tropoelastin at two sites; the initial portion of the C-terminus and the first calcium-binding epidermal growth factor-like domain at the N-terminus. Immunofluorescence staining of elastin null mouse embryonic fibroblast cultures revealed that fibulin-5 does not require elastin to be present in the ECM in order to assemble. Subsequently, solid-phase binding assays showed that fibulin-5 can bind to the N-terminus of fibrillin-1. To determine if fibulin-5 could exist independent of elastin and/or fibrillin-1 in vivo, an immunohistochemical analysis was conducted on heart, liver, lung, colon, spleen, testis and kidney. All three proteins were co-localized in all organs except in the kidney, where fibrillin-1 was found to independently stain the capillary tufts of the renal corpuscles and renal tubules. Thus, fibulin-5 may be co-regulated with elastin and is not present on elastin-independent microfibrils. Additionally, novel locations of elastic fibers were uncovered in the heart, liver, colon, spleen and testis. Overall, this study provides important insights as to the role of fibulin-5 in elastic fiber structure and assembly and also reveals the complexity in understanding the pathogenesis of diseases involving elastic fiber proteins.

Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M. Med. Sc.)--University of Hong Kong, 2005.

Millions of people around the world suffer from the debilitating effects of inflammatory bone diseases characterized by excessive bone loss due to an increase in osteoclast formation and activity. Osteoclasts are multinucleated cells responsible for bone resorption in health and disease. Arthritic joints also have elevated levels of extracellular matrix proteins affecting the disease progression. The interaction between osteoclasts and the external milieu comprised of extracellular matrix proteins through integrins is essential for modulating the formation and activity of osteoclasts. The focus of this thesis was to elucidate how the interaction between the extracellular matrix proteins and osteoclasts regulates osteoclast formation and activity and the role of alphavbeta3 in this process. In primary rabbit osteoclast cultures, blocking the integrin alphavbeta3 using Vitaxin, an anti-human alphavbeta3 antibody, decreased osteoclast resorption by decreasing osteoclast attachment. Vitaxin’s inhibitory effect on osteoclast attachment was enhanced when osteoclasts were pretreated with M-CSF, a growth factor known to induce an activated conformation of the integrin alphavbeta3. Using the RAW264.7 cell line, the effects of the matrix proteins fibronectin and vitronectin on osteoclast activity were compared to those of osteopontin. Both fibronectin and vitronectin decreased the number of osteoclasts formed compared to osteopontin. Fibronectin’s effect on osteoclastogenesis was through decreasing pre-osteoclast migration and/or fusion but not through inhibiting their recruitment. In contrast, fibronectin induced resorption through increasing resorptive activity per osteoclast in comparison to vitronectin and osteopontin. These stimulatory effects were accompanied by an increase in the pro-inflammatory cytokines nitric oxide and IL-1beta Crosstalk between the signalling pathways of nitric oxide and IL-1betawas suggested by the ability of the nitric oxide inhibitor to decrease the level of IL-1beta which occurred exclusively on fibronectin. Osteoclasts on fibronectin also had a compact morphology with the smallest planar area while vitronectin increased the percentage of osteoclast with migratory morphology and osteopontin induced osteoclast spreading. The increase in compact morphology on fibronectin was associated with a decrease in extracellular pH. Low extracellular pH was found to increase the total time osteoclasts spend in a compact phase. These results show that matrix proteins differentially regulate osteoclast formation, activity and morphology.

The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs). Since unregulated MMP activities are linked to arthritis, cancer, and atherosclerosis, TIMP variants that are selective inhibitors of disease-related MMPs have potential therapeutic value. The structures of TIMP/MMP complexes reveal that most interactions with the MMP involve the N-terminal region of TIMP and the C-D B-strand connector which occupy the primed (right side of the active site) and unprimed (left side) regions of the active site. Substitutions for Thr2 of N-TIMP- 1 strongly influence MMP selectivity. In this study we found that Arg and Gly, which generally reduce MMP affinity, have less effect on binding to MMP-9. When the Arg mutation is added to the NTIMP-1 mutant with AB loop of TIMP-2, it produced a gelatinase-specific inhibitor with Ki values of 2.8 and 0.4 nM for MMP-2 and MMP-9, respectively. The Gly mutant has a Ki of 2.1 nM for MMP-9 and > 40 uM for MMP-2, indicating that engineered TIMPs can discriminate between MMPs in the same subfamily. In collaboration with Dr. Yingnan Zhang at Genentech, we have developed a protocol for the phage display of full-length human TIMP-2 to identify high-affinity selective inhibitors of human MMP-1, a protease that plays a role in cleaving extracellular matrix (ECM) components, connective tissue remodeling during development, angiogenesis, and apoptosis. We have generated a library containing 2x1010 variants of TIMP-2 randomized at residues 2-6 (L1), at residues 34-40 (L2) and 67-70 (L3). / The L1 library yielded a positive signal for MMP-1 binding. Clones from the L1 library, designated TM1, TM8, TM13, and TM14, were isolated after 5 rounds of selection on immobilized MMP-1 and MMP-3 and found to show a greater selectivity for MMP-1 relative to MMP-3. TM8, which has Ser2 to Asp and Ser4 to Ala substitutions, showed the greatest apparent selectivity of 10-fold toward MMP-1 compared to MMP-3. The various mutations identified by phage display were introduced into recombinant Nterminal TIMP-2 and the variants characterized as inhibitors of an array of MMP catalytic domains. The TM8-based mutant showed pronounced selectivity (> 1000-fold for MMP-1 vs. MMP-3) and may be a step towards the generation of MMP-1-specific inhibitors. Molecular modeling was used to rationalize the structural basis of MMP selectivity in the mutants. / by Harinathachari Bahudhanapati. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

The 23 matrix metalloproteinases (MMPs) in humans catalyze the turnover of all protein components of the extracellular matrix (ECM) and have important roles in tissue remodeling, wound healing, embryo implantation, cell migration and shedding of cell surface proteins. Excess MMP activities are associated with many diseases including arthritis, heart disease and cancer. The activities of MMPs are regulated by a family of four protein inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), that are endogenous inhibitors of matrix metalloproteinases (MMPs), ADAMs (A Disintegrin And Metalloproteinase) and ADAMTS (disintegrin-metalloproteinase with thrombospmdin motifs) .... The balance between TIMPs and active metzinicins is very important and imbalances are linked to human diseases such as arthritis, cancer, and atherosclerosis. The engineering of TIMPs to produce specific inhibitors of individual MPs could provide new therapeutic principles for disease treatment, but this requires a detailed understanding of the biophysical and structural basis of the interactions of TIMPs and MMPs and ADAMs. / by Wu Ying. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Matrix metalloproteinases (MMPs) constitute the major class of enzymes capable of degrading all protein components of extracellular matrix (ECM) and have important roles in normal physiologic processes of maintaining tissue integrity and remodeling. However, excess MMP activities are associated with many diseases including rheumatoid arthritis and osteoarthritis, cardiomyopathy, and macular degeneration. The activity of MMPs is regulated by their endogenous protein inhibitors, the tissue inhibitors of metalloproteinases (TIMPs) which are avid broad-spectrum inhibitors of numerous human matrixins (MMPs and ADAMs). Uncontrolled matrix degradation occurs when the balance between TIMPs and MMPs is disrupted, resulting in serious diseases such as cancer, arthritis and chronic tissue ulcers. Thus, the engineering of TIMPs to produce highly selective and efficacious inhibitors of individual MMPs may be utilized for future treatment of diseases. Such engineering requires detailed analysis for the structural and biophysical information of MMP-TIMP interaction. Changes in the dynamics of proteins and solvent that accompany their associations with different binding partners, influence the specificity of binding through entropic effects. From the current studies it appears that the interactions of the inhibitory domains of TIMPs-1 and -2 (N-TIMPs) with MT1-MMP are driven by entropy increases that are partitioned between solvent and conformational entropy (ΔSsolv and ΔSconf), and a large conformational entropy penalty is responsible for the weak inhibition of MT1-MMP by NT1.We investigated how mutations that modify N-TIMP selectivity affect the thermodynamics of interactions with MMP1, MMP3 and MT1-MMP. The weak inhibition of MT1-MMP by N-TIMP-1 is enhanced by mutation of threonine 98, on the edge of the binding ridge, to leucine. This mutation increases the large ΔSconf cost for binding to MT1-MMP but this is offset by a greater increase in ΔSsolv. In contrast, this mutation enhances binding to MMP3 by increasing ΔSconf for the interaction. ΔSsolv and ΔSconf show mutual compensation for all interactions, with characteristic ranges for each MMP. Distinct electrostatic and dynamic features of MMPs are key factors in their selective inhibition. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection