449 research outputs found

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    Dynamin 2 Cooperates with Amphiphysin 1 in Phagocytosis in Sertoli Cells

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    Testicular Sertoli cells highly express dynamin 2 and amphiphysin 1. Here we demonstrate that dynamin 2 is implicated in phosphatidylserine (PS)-dependent phagocytosis in Sertoli cells. Immunofluorescence and dual-live imaging revealed that dynamin 2 and amphiphysin 1 accumulate simultaneously at ruffles. These proteins are specifically bound in vitro. Over-expression of dominant negative dynamin 2 (K44A) inhibits liposome-uptake and leads to the mis-localization of amphiphysin 1. Thus, the cooperative function of dynamin 2 and amphiphysin 1 in PS-dependent phagocytosis is strongly suggested.</p

    Identification of a Novel ACVRL1 Gene Mutation (c.100T>A, p.Cys34Ser) in a Japanese Patient with Possible Hereditary Hemorrhagic Telangiectasia (Osler-Weber-Rendu Disease)

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    Hereditary hemorrhagic telangiectasia (HHT; also known as Osler-Weber-Rendu disease) is an autosomal dominant genetic disorder that causes frequent epistaxis, mucocutaneous telangiectasia, and visceral arteriovenous malformations. Four genes (ENG, ACVRL1, SMAD4, and GDF2) have been identified as pathogenic in HHT. We describe the case of a 50-year-old Japanese man highly suspected of having HHT due to recurrent epistaxis, mucocutaneous telangiectasia, and a family history. Genomic analysis revealed a novel missense mutation of c.100T>A, p.Cys34Ser in the patient’s ACVRL1 gene. We used 6 freeware programs to perform an in silico analysis of this mutation. The results demonstrated the mutation’s high pathogenicity

    Recruitment of Irgb6 to the membrane is a direct trigger for membrane deformation

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    Irgb6 is a member of interferon gamma-induced immunity related GTPase (IRG), and one of twenty "effector" IRGs, which coordinately attack parasitophorous vacuole membrane (PVM), causing death of intracellular pathogen. Although Irgb6 plays a pivotal role as a pioneer in the process of PVM disruption, the direct effect of Irgb6 on membrane remained to be elucidated. Here, we utilized artificial lipid membranes to reconstitute Irgb6-membrane interaction in vitro, and revealed that Irgb6 directly deformed the membranes. Liposomes incubated with recombinant Irgb6 were drastically deformed generating massive tubular protrusions in the absence of guanine nucleotide, or with GMP-PNP. Liposome deformation was abolished by incubating with Irgb6-K275A/R371A, point mutations at membrane targeting residues. The membrane tubules generated by Irgb6 were mostly disappeared by the addition of GTP or GDP, which are caused by detachment of Irgb6 from membrane. Binding of Irgb6 to the membrane, which was reconstituted in vitro using lipid monolayer, was stimulated at GTP-bound state. Irgb6 GTPase activity was stimulated by the presence of liposomes more than eightfold. Irgb6 GTPase activity in the absence of membrane was also slightly stimulated, by lowering ionic strength, or by increasing protein concentration, indicating synergistic stimulation of the GTPase activity. These results suggest that membrane targeting of Irgb6 and resulting membrane deformation does not require GTP, but converting into GTP-bound state is crucial for detaching Irgb6 from the membrane, which might coincident with local membrane disruption

    Amino Acid Sequence of the α Chain of Chicken AI Hemoglobin I. Amino Acid Sequence of the Tryptic Peptides of the α Chain

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    Adult chicken hemoglobin is heterogeneous containing two major components, A and AII9). αpolypeptide chain of A I component was purified and subjected to tryptic digestion for 3 hr. Each tryptic peptide was purified by AG 1 x 2 column chromatography, Chromo Beads P column chromatography and paper chromatography in sequence and the amino acid sequence of each peptide was studied. A brief report on the results of this study was already presented as a preliminary communication"\u27. This communication deals with the details on the structural studies of a polypeptide chain of A I component from chicken adult hemoglobin

    Spontaneous Vacuolar Degeneration of the Thyroid Follicular Epithelium in Cynomolgus Monkeys

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    Vacuolar degeneration of the thyroid follicular epithelium was observed in two untreated female cynomolgus monkeys assigned to control groups. In light microscopy, large vacuoles containing a homogenous substance occupied the basal region of the epithelium, and the nuclei had shifted toward the apical region. The vacuoles showed negative reactions to PAS and thyroglobulin. Electron microscopic observation revealed dilatation of the rough endoplasmic reticulum corresponding to the vacuoles. The plasma TSH, T3 and T4 levels determined for the samples kept frozen were within the normal ranges, suggesting that the thyroid function was kept intact
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