Regulatory properties of vitronectin and its glycosylation in collagen fibril formation and collagen-degrading enzyme cathepsin K activity

Abstract Vitronectin (VN) is a glycoprotein found in extracellular matrix and blood. Collagen, a major extracellular matrix component in mammals, is degraded by cathepsin K (CatK), which is essential for bone resorption under acidic conditions. The relationship between VN and cathepsins has been unclear. We discovered that VN promoted collagen fibril formation and inhibited CatK activity, and observed its activation in vitro. VN accelerated collagen fibril formation at neutral pH. Collagen fibers formed with VN were in close contact with each other and appeared as scattered flat masses in scanning electron microscopy images. VN formed collagen fibers with high acid solubility and significantly inhibited CatK; the IC50 was 8.1–16.6 nM and competitive, almost the same as those of human and porcine VNs. VN inhibited the autoprocessing of inactive pro-CatK from active CatK. DeN-glycosylation of VN attenuated the inhibitory effects of CatK and its autoprocessing by VN, but had little effect on acid solubilization of collagen and VN degradation via CatK. CatK inhibition is an attractive treatment approach for osteoporosis and osteoarthritis. These findings suggest that glycosylated VN is a potential biological candidate for CatK inhibition and may help to understand the molecular mechanisms of tissue re-modeling

Mycoplasma pneumoniae 感染に併発した両側感音性難聴

We report an 11-year-old girl, who suffered from Mycoplasma pneumoniae pneumonia, meningitis, and mild, bilateral, acute otitis media, with subsequent severe, mixed hearing loss. The patient presented extremely high Mycoplasma pneumoniae complement fixation and cold hemagglutinin titers, the unique chest x-rays indicating mycoplasma pneumonia, and cerebrospinal fluid suggestive of meningitis. A moderate grade of sensorineural hearing loss that was seen in the early clinical stage has not shown any improvement, although the other signs and symptoms have resolved. Possible causative relationships of Mycoplasma pneumoniae to otologic complications, especially those closely related to peripheral nerve impairments, were discussed

Secretion of Active-Form Streptoverticillium mobaraense Transglutaminase by Corynebacterium glutamicum: Processing of the Pro-Transglutaminase by a Cosecreted Subtilisin-Like Protease from Streptomyces albogriseolus

The transglutaminase secreted by Streptoverticillium mobaraense is a useful enzyme in the food industry. A fragment of transglutaminase was secreted by Corynebacterium glutamicum when it was coupled on a plasmid to the promoter and signal peptide of a cell surface protein from C. glutamicum. We analyzed the signal peptide and the pro-domain of the transglutaminase gene and found that the signal peptide consists of 31 amino acid residues and the pro-domain consists of 45 residues. When the pro-domain of the transglutaminase was used, the pro-transglutaminase was secreted efficiently by C. glutamicum but had no enzymatic activity. However, when the plasmid carrying the S. mobaraense transglutaminase also encoded SAM-P45, a subtilisin-like serine protease derived from Streptomyces albogriseolus, the peptide bond to the C side of 41-Ser of the pro-transglutaminase was hydrolyzed, and the pro-transglutaminase was converted to an active form. Our findings suggest that C. glutamicum has potential as a host for industrial-scale protein production

Production of Native-Type Streptoverticillium mobaraense Transglutaminase in Corynebacterium glutamicum

We previously observed secretion of active-form transglutaminase in Corynebacterium glutamicum by coexpressing the subtilisin-like protease SAM-P45 from Streptomyces albogriseolus to process the prodomain. However, the N-terminal amino acid sequence of the transglutaminase differed from that of the native Streptoverticillium mobaraense enzyme. In the present work we have used site-directed mutagenesis to generate an optimal SAM-P45 cleavage site in the C-terminal region of the prodomain. As a result, native-type transglutaminase was secreted

Hypoxia-inducible factor 1 promotes chemoresistance of lung cancer by inducing carbonic anhydrase IX expression

Lung cancer treatment is difficult owing to chemoresistance. Hypoxia-inducible factor 1 (HIF-1) and HIF-1-induced glycolysis are correlated with chemoresistance; however, this is not evident in lung cancer. We investigated the effect of HIF-1α and carbonic anhydrase IX (CAIX), a transmembrane protein neutralizing intracellular acidosis, on chemoresistance and prognosis of lung cancer patients after induction chemoradiotherapy. Associations of HIF-1α, glucose transporter 1 (GLUT1), and CAIX with chemoresistance of lung cancer were investigated using A549 lung cancer cells under normoxia or hypoxia in vitro. HIF-1α-induced reprogramming of glucose metabolic pathway in A549 cells and the effects of HIF-1 and CAIX on the cytotoxicity of vinorelbine were investigated. Immunohistochemical analyses were performed to determine HIF-1α, GLUT1, and CAIX expression levels in cancer specimens from lung cancer patients after induction chemoradiotherapy. Hypoxia induced HIF-1α expression in A549 cells. Moreover, hypoxia induced GLUT1 and CAIX expression in A549 cells in a HIF-1-dependent manner. Glucose metabolic pathway was shifted from oxidative phosphorylation to glycolysis by inducing HIF-1α in A549 cells. HIF-1 and CAIX induced chemoresistance under hypoxia, and their inhibition restored the chemosensitivity of A549 cells. The expression levels of HIF-1α, GLUT1, and CAIX were associated with poor overall survival of lung cancer patients after induction chemoradiotherapy. HIF-1 and CAIX affected the chemosensitivity of A549 cells and prognosis of lung cancer patients. Therefore, inhibition of HIF-1 and CAIX might improve prognosis of lung cancer patients after induction chemoradiotherapy. Further analysis might be helpful in developing therapies for lung cancer