Roles of Toll-like Receptor Signaling in Inflammatory Bone Resorption.

Toll-like receptors (TLRs) are pattern recognition receptors expressed in immune cells, including neutrophils, macrophages, and dendritic cells. Microbe-associated molecular patterns, including bacterial components, membranes, nucleic acids, and flagella are recognized by TLRs in inflammatory immune responses. Periodontal disease is an inflammatory disease known to cause local infections associated with gingival inflammation, subsequently leading to alveolar bone resorption.

Vesicle transport of matrix metalloproteinases.

Multicellular organisms consist of cells and extracellular matrix (ECM). ECM creates a cellular microenvironment, and cells locally degrade the ECM according to their cellular activity. A major group of enzymes that modify ECM belongs to matrix metalloproteinases (MMPs) and play major roles in various pathophysiological events.

Assembly of neuron- and radial glial-cell-derived extracellular matrix molecules promotes radial migration of developing cortical neurons.

Radial neuronal migration is a key neurodevelopmental event for proper cortical laminar organization. The multipolar-to-bipolar transition, a critical step in establishing neuronal polarity during radial migration, occurs in the subplate/intermediate zone (SP/IZ), a distinct region of the embryonic cerebral cortex. It has been known that the extracellular matrix (ECM) molecules are enriched in the SP/IZ.

The stiffness and collagen control differentiation of osteoclasts with an altered expression of c-Src in podosome.

Osteoclasts are hematopoietic cells attached to the bones containing type I collagen-deposited hydroxyapatite during bone resorption. Two major elements determine the stiffness of bones: regular calcified bone (bone that is resorbable by osteoclasts) and un-calcified osteoid bone (bone that is un-resorbable by osteoclasts). The osteolytic cytokine RANKL promotes osteoclast differentiation; however, the roles of the physical interactions of osteoclasts with calcified and un-calcified bone at the sealing zones and the subsequent cellular signaling remain unclear.

Establishment of a Triple Quadrupole HPLC-MS Quantitation Method for Dystrophin Protein in Mouse and Human Skeletal Muscle.

Duchenne muscular dystrophy (DMD) is the most common type of neuromuscular disease caused by mutations in the gene encoding dystrophin protein. To quantitively assess human dystrophin protein in muscle biopsy samples, it is imperative to consistently detect as low as 0.003% of the dystrophin protein relative to the total muscle protein content.

Investigation of MT1-MMP Activity in Cancer Cells.

Membrane-type 1 matrix metalloproteinase (MT1-MMP, also called MMP14) is one of the significant cell invasion drivers. MT1-MMP has been shown to play a crucial role in cancer invasion, cartilage degradation in rheumatoid arthritis, angiogenesis, and collagen homeostasis in different stromal tissues. Thus, investigating MT1-MMP activities in different cell types is of interest to investigators in different research fields.

Mmp14 is required for matrisome homeostasis and circadian rhythm in fibroblasts.

The circadian clock in tendon regulates the daily rhythmic synthesis of collagen-I and the appearance and disappearance of small-diameter collagen fibrils in the extracellular matrix. How the fibrils are assembled and removed is not fully understood. Here, we first showed that the collagenase, membrane type I-matrix metalloproteinase (MT1-MMP, encoded by Mmp14), is regulated by the circadian clock in postnatal mouse tendon.

Degradomic Identification of Membrane Type 1-Matrix Metalloproteinase as an ADAMTS9 and ADAMTS20 Substrate.

The secreted metalloproteases ADAMTS9 and ADAMTS20 are implicated in extracellular matrix proteolysis and primary cilium biogenesis. Here, we show that clonal gene-edited RPE-1 cells in which ADAMTS9 was inactivated, and which constitutively lack ADAMTS20 expression, have morphologic characteristics distinct from parental RPE-1 cells. To investigate underlying proteolytic mechanisms, a quantitative terminomics method, terminal amine isotopic labeling of substrates was used to compare the parental and gene-edited RPE-1 cells and their medium to identify ADAMTS9 substrates.

Prostate cancer expressing membrane-bound TGF-α induces bone formation mediated by the autocrine effect of prostaglandin E in osteoblasts.

Prostate cancer highly metastasizes to bone, and such cancer is associated with severe bone resorption and bone formation at the site of metastasis. Prostaglandin E (PGE) promotes bone resorption in inflammatory diseases; however, the roles in prostate cancer-induced bone formation are still unclear. In the present study, we investigated the effects of membrane-bound TGF-α on prostate cancer-induced bone formation through autocrine PGE signaling in osteoblasts.

Proteolytic modulation of tumor microenvironment signals during cancer progression.

Under normal conditions, the cellular microenvironment is optimized for the proper functioning of the tissues and organs. Cells recognize and communicate with the surrounding cells and extracellular matrix to maintain homeostasis. When cancer arises, the cellular microenvironment is modified to optimize its malignant growth, evading the host immune system and finding ways to invade and metastasize to other organs.

A mouse model of lung cancer induced via intranasal injection for anticancer drug screening and evaluation of pathology.

The pathologies and lethality of lung cancers are associated with smoking, lifestyle, and genomic factors. Several experimental mouse models of lung cancer, including those induced via intrapulmonary injection and intratracheal injection, have been reported for evaluating the pharmacological effect of drugs. However, these models are not sufficient for evaluating the efficacy of drugs during screening, as these direct injection models ignore the native processes of cancer progression in vivo, resulting in the inadequate pathological formation of lung cancer.

Coordination of two kinesin superfamily motor proteins, KIF3A and KIF13A, is essential for pericellular matrix degradation by membrane-type 1 matrix metalloproteinase (MT1-MMP) in cancer cells.

MT1-MMP plays a crucial role in promoting the cellular invasion of cancer cells by degrading the extracellular matrix to create a path for migration. During this process, its localization at the leading edge of migrating cells is critical, and it is achieved by targeted transport of MT1-MMP-containing vesicles along microtubules by kinesin superfamily motor proteins (KIFs). Here we identified three KIFs involved in MT1-MMP vesicle transport: KIF3A, KIF13A, and KIF9.

Endosomal TLR3 signaling in stromal osteoblasts induces prostaglandin E-mediated inflammatory periodontal bone resorption.

Toll-like receptors (TLRs) are pattern recognition receptors that play a critical role in innate immune diseases. TLR3, which is localized in the endosomal compartments of hematopoietic immune cells, is able to recognize double-stranded RNA (dsRNA) derived from viruses and bacteria and thereby induce innate immune responses. Inflammatory periodontal bone resorption is caused by bacterial infections, which initially is regulated by innate immunity; however, the roles of TLR3 signaling in bone resorption are still not known.

Alpha-2-Macroglobulin in Inflammation, Immunity and Infections.

Alpha-2-macroglobulin is an extracellular macromolecule mainly known for its role as a broad-spectrum protease inhibitor. By presenting itself as an optimal substrate for endopeptidases of all catalytic types, alpha-2-macroglobulin lures active proteases into its molecular cage and subsequently 'flags' their complex for elimination. In addition to its role as a regulator of extracellular proteolysis, alpha-2-macroglobulin also has other functions such as switching proteolysis towards small substrates, facilitating cell migration and the binding of cytokines, growth factors and damaged extracellular proteins.

Modulation of Microenvironment Signals by Proteolytic Shedding of Cell Surface Extracellular Matrix Receptors.

Multicellular organisms are composed of cells and extracellular matrix (ECM). ECM is a network of multidomain macromolecules that fills gaps between cells. It acts as a glue to connect cells, provides scaffolding for migrating cells, and pools cytokines and growth factors.

Gram-positive bacteria cell wall-derived lipoteichoic acid induces inflammatory alveolar bone loss through prostaglandin E production in osteoblasts.

Periodontitis is an inflammatory disease associated with severe alveolar bone loss and is dominantly induced by lipopolysaccharide from Gram-negative bacteria; however, the role of Gram-positive bacteria in periodontal bone resorption remains unclear. In this study, we examined the effects of lipoteichoic acid (LTA), a major cell-wall factor of Gram-positive bacteria, on the progression of inflammatory alveolar bone loss in a model of periodontitis. In coculture of mouse primary osteoblasts and bone marrow cells, LTA induced osteoclast differentiation in a dose-dependent manner.

A common SNP risk variant MT1-MMP causative for Dupuytren's disease has a specific defect in collagenolytic activity.

Dupuytren's Disease (DD) is a common fibroproliferative disease of the palmar fascia. We previously identified a causal association with a non-synonymous variant (rs1042704, p.D273N) in MMP14 (encoding MT1-MMP).

Autofluorescence Lifetime Reports Cartilage Damage in Osteoarthritis.

Osteoarthritis (OA) is the most common arthritis and its hallmark is degradation of articular cartilage by proteolytic enzymes leading to loss of joint function. It is challenging to monitor the status of cartilage in vivo and this study explores the use of autofluorescence lifetime (AFL) measurements to provide a label-free optical readout of cartilage degradation that could enable earlier detection and evaluation of potential therapies. We previously reported that treatment of ex vivo porcine cartilage with proteolytic enzymes resulted in decreased AFL.

MT1-MMP-dependent cell migration: proteolytic and non-proteolytic mechanisms.

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a type I transmembrane proteinase that belongs to the matrix metalloproteinase (MMP) family. It is a potent modifier of cellular microenvironment and promotes cell migration and invasion of a wide variety of cell types both in physiological and pathological conditions. It promotes cell migration by degrading extracellular matrix on the cell surface and creates a migration path, by modifying cell adhesion property by shedding cell adhesion molecules to increase cell motility, and by altering cellular metabolism.

Hypergravity and microgravity exhibited reversal effects on the bone and muscle mass in mice.

Spaceflight is known to induce severe systemic bone loss and muscle atrophy of astronauts due to the circumstances of microgravity. We examined the influence of artificially produced 2G hypergravity on mice for bone and muscle mass with newly developed centrifuge device. We also analyzed the effects of microgravity (mostly 0G) and artificial produced 1G in ISS (international space station) on mouse bone mass.

Epithelial polarization in 3D matrix requires DDR1 signaling to regulate actomyosin contractility.

Epithelial cells form sheets and tubules in various epithelial organs and establish apicobasal polarity and asymmetric vesicle transport to provide functionality in these structures. However, the molecular mechanisms that allow epithelial cells to establish polarity are not clearly understood. Here, we present evidence that the kinase activity of the receptor tyrosine kinase for collagen, discoidin domain receptor 1 (DDR1), is required for efficient establishment of epithelial polarity, proper asymmetric protein secretion, and execution of morphogenic programs.

Design, synthesis and biological evaluation of bifunctional inhibitors of membrane type 1 matrix metalloproteinase (MT1-MMP).

Collagen degradation and proMMP-2 activation are major functions of MT1-MMP to promote cancer cell invasion. Since both processes require MT1-MMP homodimerization on the cell surface, herein we propose that the use of bifunctional inhibitors of this enzyme could represent an innovative approach to efficiently reduce tumor growth. A small series of symmetrical dimers derived from previously described monomeric arylsulfonamide hydroxamates was synthesized and tested in vitro on isolated MMPs.

Discoidin domain receptors: Microenvironment sensors that promote cellular migration and invasion.

Extracellular matrix (ECM) provides cells scaffolding for cell migration and microenvironment for various cellular functions. Collagens are major ECM components in tissue and discoidin domain receptors (DDRs) are receptor tyrosine kinases (RTK) that recognise fibrillar collagens. Unlike other RTK, their ligands are solid ECM the that are abundantly present in the pericellular environment in various tissue, and thus its activation and regulations are unique amongst RTK family.

Metalloproteinases in Rheumatoid Arthritis: Potential Therapeutic Targets to Improve Current Therapies.

Rheumatoid arthritis (RA) is a systemic inflammatory disease characterized by the destruction of joint tissues including cartilage and bone. Cartilage degradation is attributed to metalloproteinases (MPs) that belong to matrix metalloproteinase family and a disintegrin and metalloprotease with thrombospondin type 1 motifs produced by inflamed joint tissues. In addition, an enzyme that belongs to a disintegrin and metalloprotease family is also involved in release of inflammatory cytokines.