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  • Proceedings of the National Academy of Sciences  (3)
  • Natural Sciences  (3)
  • 1
    Online Resource
    Online Resource
    Thrombin cleaves recombinant human thrombopoietin: One of the proteolytic events that generates truncated forms of thrombopoietin
    Proceedings of the National Academy of Sciences ; 1997
    In:  Proceedings of the National Academy of Sciences Vol. 94, No. 9 ( 1997-04-29), p. 4669-4674
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 94, No. 9 ( 1997-04-29), p. 4669-4674
    Abstract: A heterogeneity in the molecular weight ( M r ) of thrombopoietin (TPO) has been reported. We found several thrombin cleavage sites in human, rat, murine, and canine TPOs, and also found that human TPO undergoes selective proteolysis by thrombin. Recombinant human TPO (rhTPO) was incubated with human platelets in the presence of calcium ions to allow the generation of thrombin, and was cleaved into low M r peptide fragments. The cleavage was completely inhibited by hirudin, indicating that the proteolysis was mediated by thrombin. In a platelet-free system, analyses of thrombin cleavage by immunoblotting using anti-human TPO peptide antibodies revealed that the four major thrombin-cleaved peptide fragments were selectively generated depending on the digestion time. The amino acid sequences of the thrombin-polypeptides were further analyzed, and two major thrombin cleavage sites were determined. One of them was at AR 191 -T 192 in the C-terminal domain of TPO, and thrombin cleaved first at this site. The other site at GR 117 -T 118 in the N-terminal domain was subsequently cleaved by prolonged thrombin digestion. As a result, the biological activity of TPO was modulated. The generation of truncated forms of TPO by thrombin may be a notable event in view of the platelet-related metabolism of TPO.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.94.9.4669
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1997
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Grafted human-induced pluripotent stem-cell–derived neurospheres promote motor functional recovery after spinal cord injury in mice
    Proceedings of the National Academy of Sciences ; 2011
    In:  Proceedings of the National Academy of Sciences Vol. 108, No. 40 ( 2011-10-04), p. 16825-16830
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 108, No. 40 ( 2011-10-04), p. 16825-16830
    Abstract: Once their safety is confirmed, human-induced pluripotent stem cells (hiPSCs), which do not entail ethical concerns, may become a preferred cell source for regenerative medicine. Here, we investigated the therapeutic potential of transplanting hiPSC-derived neurospheres (hiPSC-NSs) into nonobese diabetic (NOD)-severe combined immunodeficient (SCID) mice to treat spinal cord injury (SCI). For this, we used a hiPSC clone (201B7), established by transducing four reprogramming factors (Oct3/4, Sox2, Klf4, and c-Myc) into adult human fibroblasts. Grafted hiPSC-NSs survived, migrated, and differentiated into the three major neural lineages (neurons, astrocytes, and oligodendrocytes) within the injured spinal cord. They showed both cell-autonomous and noncell-autonomous (trophic) effects, including synapse formation between hiPSC-NS–derived neurons and host mouse neurons, expression of neurotrophic factors, angiogenesis, axonal regrowth, and increased amounts of myelin in the injured area. These positive effects resulted in significantly better functional recovery compared with vehicle-treated control animals, and the recovery persisted through the end of the observation period, 112 d post-SCI. No tumor formation was observed in the hiPSC-NS–grafted mice. These findings suggest that hiPSCs give rise to neural stem/progenitor cells that support improved function post-SCI and are a promising cell source for its treatment.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1108077108
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2011
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Phospholipase Cβ1 induces membrane tubulation and is involved in caveolae formation
    Proceedings of the National Academy of Sciences ; 2016
    In:  Proceedings of the National Academy of Sciences Vol. 113, No. 28 ( 2016-07-12), p. 7834-7839
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 113, No. 28 ( 2016-07-12), p. 7834-7839
    Abstract: Lipid membrane curvature plays important roles in various physiological phenomena. Curvature-regulated dynamic membrane remodeling is achieved by the interaction between lipids and proteins. So far, several membrane sensing/sculpting proteins, such as Bin/amphiphysin/Rvs (BAR) proteins, are reported, but there remains the possibility of the existence of unidentified membrane-deforming proteins that have not been uncovered by sequence homology. To identify new lipid membrane deformation proteins, we applied liposome-based microscopic screening, using unbiased-darkfield microscopy. Using this method, we identified phospholipase Cβ1 (PLCβ1) as a new candidate. PLCβ1 is well characterized as an enzyme catalyzing the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP 2 ). In addition to lipase activity, our results indicate that PLCβ1 possessed the ability of membrane tubulation. Lipase domains and inositol phospholipids binding the pleckstrin homology (PH) domain of PLCβ1 were not involved, but the C-terminal sequence was responsible for this tubulation activity. Computational modeling revealed that the C terminus displays the structural homology to the BAR domains, which is well known as a membrane sensing/sculpting domain. Overexpression of PLCβ1 caused plasma membrane tubulation, whereas knockdown of the protein reduced the number of caveolae and induced the evagination of caveolin-rich membrane domains. Taken together, our results suggest a new function of PLCβ1: plasma membrane remodeling, and in particular, caveolae formation.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1603513113
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2016
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
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