Establishment of X-linked Alport syndrome model mice with a Col4a5 R471X mutation

Alport syndrome (AS) is an inherited disorder characterized by glomerular basement membrane (GBM) abnormality and development of chronic kidney disease at an early age. The cause of AS is a genetic mutation in type IV collagen, and more than 80% of patients have X-linked AS (XLAS) with mutation in COL4A5. Although the causal gene has been identified, mechanisms of progression have not been elucidated, and no effective treatment has been developed. In this study, we generated a Col4a5 mutant mouse harboring a nonsense mutation (R471X) obtained from a patient with XLAS using clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated system. Col4a5 mRNA and protein expressions were not observed in the kidneys of hemizygous R471X male mice. R471X mice showed proteinuria and hematuria. Pathology revealed progression of glomerulosclerosis and interstitial fibrosis by age. Electron microscopy identified irregular thickening in GBM accompanied by irregular lamination. These observations were consistent with the clinical and pathological features of patients with AS and other established models. In addition, our mice models develop end-stage renal disease at the median age of 28 weeks, much later compared to previous models much more consistent with clinical course of human XLAS. Our models have advantages for future experiments in regard with treatment for human XLAS.     

Trifluoroethanol‐containing RP‐HPLC mobile phases for the separation of transmembrane peptides human glycophorin‐A,integrin alpha‐1, and p24: analysis and prevention of potential side reactions due to formic acid

Reversed‐phase high‐pressure liquid chromatography analysis and purification of three hydrophobic, aggregation‐prone peptides, composed mainly of the transmembrane (TM) sequence, were performed using elution systems containing 2,2,2‐trifluoroethanol (TFE). The addition of 10–16% TFE to a common mobile phase, such as a water/acetonitrile/propanol (PrOH) or a water/PrOH/formic acid system, markedly improved the chromatographic separation of these peptides. The superior performance of TFE‐containing systems in separating peptides over water/PrOH/formic acid systems [Bollhagen R. et al., J. Chromatogr. A, 1995; 711 : 181–186.] clearly demonstrated that adding TFE to the mobile phase is one of best methods for TM‐peptide purification. Characterization of the potential side reactions using MALDI and ESI‐LIT/Orbitrap mass spectrometry indicated that prolonged incubation of peptides in a mixture of TFE–formic acid possibly induces O‐formylation of the Ser residue and N‐formylation of the N‐terminus of peptides. The conditions for selective removal of the formyl groups from TM peptides were also screened. We believe that these results will expand our ability to analyze and prepare hydrophobic, aggregation‐prone TM peptides and proteins. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Theonellamide A,a marine-sponge-derived bicyclic peptide,binds to cholesterol in aqueous DMSO: Solution NMR-based analysis of peptide-sterol interactions using hydroxylated sterol

Theonellamides (TNMs) are antifungal and cytotoxic bicyclic dodecapeptides isolated from the marine sponge Theonella sp. The inclusion of cholesterol (Chol) or ergosterol in the phosphatidylcholine membrane is known to significantly enhance the membrane affinity for theonellamide A (TNM-A). We have previously revealed that TNM-A stays in a monomeric form in dimethylsulfoxide (DMSO) solvent systems, whereas the peptide forms oligomers in aqueous media. In this study, we utilized ¹H NMR chemical shift changes (Δδ_1H) in aqueous DMSO solution to evaluate the TNM-A/sterol interaction. Because Chol does not dissolve well in this solvent, we used 25-hydroxycholesterol (25-HC) instead, which turned out to interact with membrane-bound TNM-A in a very similar way to that of Chol. We determined the dissociation constant, K_D, by NMR titration experiments and measured the chemical shift changes of TNM-A induced by 25-HC binding in the DMSO solution. Significant changes were observed for several amino acid residues in a certain area of the molecule. The results from the solution NMR experiments, together with previous findings, suggest that the TNM-Chol complex, where the hydrophobic cavity of TNM probably incorporates Chol, becomes less polar by Chol interaction, resulting in a greater accumulation of the peptide in membrane. The deeper penetration of TNM-A into the membrane interior enhances membrane disruption. We also demonstrated that hydroxylated sterols, such as 25-HC that has higher solubility in most NMR solvents than Chol, act as a versatile substitute for sterol and could be used in ¹H NMR-based studies of sterol-binding peptides.     

Infection of human hepatocyte chimeric mouse with genetically engineered hepatitis C virus and its susceptibility to interferon

We developed a reverse genetics system of hepatitis C virus (HCV) genotypes 1a and 2a using infectious clones and human hepatocyte chimeric mice. We inoculated cell culture-produced genotype 2a (JFH-1) HCV intravenously. We also injected genotype 1a CV-H77C clone RNA intrahepatically. Mice inoculated with HCV by both procedures developed measurable and transmissible viremia. Interferon (IFN) alpha treatment resulted in greater reduction of genotype 2a HCV levels than genotype 1a, as seen in clinical practice. Genetically engineered HCV infection system should be useful for analysis of the mechanisms of resistance of HCV to IFN and other drugs.     

Anaplastic oligodendroglioma: a case report with characteristic cytologic features, including minigemistocytes

BACKGROUND: Absolute criteria for grading oligodendrogliomas are somewhat poorly defined in contrast to those for grading astrocytic tumors, and cytologic features of anaplastic oligodendrogliomas have been poorly described. CASE: A 63-year-old man presented with a toppling gait. Radiologic examination revealed a 7-cm mass with calcifications in the right frontal lobe. Intraoperative smears of the tumor showed hypercellular, loosely cohesive cell clusters and single cells with nuclear pleomorphism, numerous apoptotic cells and no discernible fibrillary processes. Many bland-looking round cells with cyanophilic cytoplasm and eccentrically located nuclei, so-called minigemistocytes, were intermingled among atypical cells. Cryostat sections showed cellular nests consisting of tumor cells with oval nuclei and clear cytoplasm. These cells were proliferating in the finely reticulated vascular stroma, and the tumor had an infiltrative margin with areas of focal necrosis and numerous calcifications. The diagnosis of anaplastic oligodendroglioma, World Health Organization grade 3, was made, and the results of fluorescence in situ hybridization (chromosome 1q deletion) supported the diagnosis. CONCLUSION: Intraoperative diagnosis of anaplastic oligodendroglioma may not be easy but is possible with judicious consideration of several features: high cellularity, no fibrillary processes, nuclear atypia, pleomorphism, abundant apoptotic cells, occasional mitotic figures, coagulative necrosis, endothelial hyperplasia and characteristic conspicuous minigemistocytes.     

Fortilin binds Ca2+ and blocks Ca2+-dependent apoptosis in vivo

Fortilin, a 172-amino-acid polypeptide present both in the cytosol and nucleus, possesses potent anti-apoptotic activity. Although fortilin is known to bind Ca2+, the biochemistry and biological significance of such an interaction remains unknown. In the present study we report that fortilin must bind Ca2+ in order to protect cells against Ca2+-dependent apoptosis. Using a standard Ca2+-overlay assay, we first validated that full-length fortilin binds Ca2+ and showed that the N-terminus (amino acids 1-72) is required for its Ca2+-binding. We then used flow dialysis and CD spectropolarimetry assays to demonstrate that fortilin binds Ca2+ with a dissociation constant (Kd) of approx. 10 mM and that the binding of fortilin to Ca2+ induces a significant change in the secondary structure of fortilin. In order to evaluate the impact of the binding of fortilin to Ca2+ in vivo, we measured intracellular Ca2+ levels upon thapsigargin challenge and found that the lack of fortilin in the cell results in the exaggerated elevation of intracellular Ca2+ in the cell. We then tested various point mutants of fortilin for their Ca2+ binding and identified fortilin(E58A/E60A) to be a double-point mutant of fortilin lacking the ability of Ca2+-binding. We then found that wild-type fortilin, but not fortilin(E58A/E60A), protected cells against thapsigargin-induced apoptosis, suggesting that the binding of fortilin to Ca2+ is required for fortilin to protect cells against Ca2+-dependent apoptosis. Together, these results suggest that fortilin is an intracellular Ca2+ scavenger, protecting cells against Ca2+-dependent apoptosis by binding and sequestering Ca2+ from the downstream Ca2+-dependent apoptotic pathways.     

Interaction of the C-Terminal Tail of FliF with FliG from the Na+-Driven Flagellar Motor of Vibrio alginolyticus

Rotation of the polar flagellum of Vibrio alginolyticus is driven by a Na⁺-type flagellar motor. FliG, one of the essential rotor proteins located at the upper rim of the C ring, binds to the membrane-embedded MS ring. The MS ring is composed of a single membrane protein, FliF, and serves as a foundation for flagellar assembly. Unexpectedly, about half of the Vibrio FliF protein produced at high levels in Escherichia coli was found in the soluble fraction. Soluble FliF purifies as an oligomer of ∼700 kDa, as judged by analytical size exclusion chromatography. By using fluorescence correlation spectroscopy, an interaction between a soluble FliF multimer and FliG was detected. This binding was weakened by a series of deletions at the C-terminal end of FliF and was nearly eliminated by a 24-residue deletion or a point mutation at a highly conserved tryptophan residue (W575). Mutations in FliF that caused a defect in FliF-FliG binding abolish flagellation and therefore confer a nonmotile phenotype. As data from in vitro binding assays using the soluble FliF multimer correlate with data from in vivo functional analyses, we conclude that the C-terminal region of the soluble form of FliF retains the ability to bind FliG. Our study confirms that the C-terminal tail of FliF provides the binding site for FliG and is thus required for flagellation in Vibrio, as reported for other species. This is the first report of detection of the FliF-FliG interaction in the Na⁺-driven flagellar motor, both in vivo and in vitro.