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Volume 27, Issue 1
Displaying 1-6 of 6 articles from this issue
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REVIEW
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Noriyuki Kioka, Kazumitsu Ueda, Teruo AmachiArticle type: scientific monograph
Subject area: Cell Structure and Function
2002 Volume 27 Issue 1 Pages 1-7
Published: 2002
Released on J-STAGE: April 05, 2002
JOURNAL FREE ACCESSAdaptor proteins, composed of two or more protein-protein interacting modules without enzymatic activity, regulate various cellular functions. Vinexin, CAP/ponsin, and ArgBP2 constitute a novel adaptor protein family. They have a novel conserved region homologous to the active peptide sorbin, as well as three SH3 (src homology 3) domains. A number of proteins binding to this adaptor family have been identified. There is accumulating evidence that this protein family regulates cell adhesion, cytoskeletal organization, and growth factor signaling. This review will summarize the structure and the function of proteins in this family.
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REGULAR ARTICLES
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Yasuko Tomono, Ichiro Naito, Kaori Ando, Tomoko Yonezawa, Yoshikazu Sa ...Article type: scientific monograph
Subject area: Cell Structure and Function
2002 Volume 27 Issue 1 Pages 9-20
Published: 2002
Released on J-STAGE: April 05, 2002
JOURNAL FREE ACCESSType XV and type XVIII collagens are classified as part of multiplexin collagen superfamily and their C-terminal parts, endostatin and restin, respectively, have been shown to be anti-angiogenic in vivo and in vitro. The α1(XV) and α1(XVIII) collagen chains are reported to be localized mainly in the basement membrane zone, but their distributions in blood vessels and nonvascular tissues have yet to be thoroughly clarified. In the present study, we raised monoclonal antibodies against synthetic peptides of human α1(XV) and α1(XVIII) chains and used them for extensive investigation of the distribution of these chains. We came to the conclusion that nonvascular BMs contain mainly one of two types: subepithelial basement membranes that contained type XVIII in general, or skeletal and cardiac muscles that harbored mainly type XV. But basement membranes surrounding smooth muscle cells in vascular tissues contained one or both of them, depending on their locations. Interestingly, continuous capillaries contained both type XV and type XVIII collagens in their basement membranes; however, fenestrated or specialized capillaries such as glomeruli, liver sinusoids, lung alveoli, and splenic sinusoids expressed only type XVIII in their basement membranes, lacking type XV. This observation could imply that different functions of basement membranes in various tissues and organs use different mechanisms for the endogenous control of angiogenesis.
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Motoko Shibanuma, Yasuhiko Iwabuchi, Kiyoshi NoseArticle type: scientific monograph
Subject area: Cell Structure and Function
2002 Volume 27 Issue 1 Pages 21-27
Published: 2002
Released on J-STAGE: April 05, 2002
JOURNAL FREE ACCESSHic-5, a focal adhesion protein, has been implicated in cellular senescence and differentiation. In this study, we examined its involvement in myogenic differentiation. The hic-5 expression level in growing C2C12 myoblasts increased slightly on the first day and then gradually decreased until no hic-5 was detectable after 7 days of differentiation. In vivo, its expression level declined in the thigh and the calf skeletal muscle of mouse embryos after birth. The introduction of an antisense expression vector of hic-5 into C2C12 cells decreased the number of clones expressing the myosin heavy chain (MHC) upon exposure to the differentiation medium. In the cloned cells with low levels of hic-5, the efficiency of myotube formation was significantly reduced. The expression levels of MyoD, myogenin, MHC and p21 were also reduced in these clones. The results suggested that hic-5 plays a role in the initial stage of myogenic differentiation.
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Atsuki Nara, Noboru Mizushima, Akitsugu Yamamoto, Yukiko Kabeya, Yoshi ...Article type: scientific monograph
Subject area: Cell Structure and Function
2002 Volume 27 Issue 1 Pages 29-37
Published: 2002
Released on J-STAGE: April 05, 2002
JOURNAL FREE ACCESSMouse SKD1 AAA ATPase is involved in the sorting and transport from endosomes; cells overexpressing a dominant-negative mutant, SKD1E235Q were defective in endosomal transport to both the plasma membranes and lysosomes (Yoshimori et al., 2000). In the present study, we demonstrated that overexpression of SKD1E235Q using an adenovirus delivery system caused a defect in autophagy-dependent bulk protein degradation. Morphological observations suggested that this inhibition of autophagy results from an impairment of autolysosome formation. SKD1E235Q overexpression also inhibited transport from endosomes to autophagosomes, an event normally occurring prior to fusion with lysosomes. These results indicate that SKD1-dependent endosomal membrane trafficking is required for formation of autolysosomes.
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Yosuke Matsuoka, Yuriko Matsuoka, Satoshi Shibata, Yoshihiro YonedaArticle type: scientific monograph
Subject area: Cell Structure and Function
2002 Volume 27 Issue 1 Pages 39-45
Published: 2002
Released on J-STAGE: April 05, 2002
JOURNAL FREE ACCESSWe previously reported that exogenous histone H1, when injected into mitotic cells, disrupts the synchronous progression of mitotic events by delaying chromosome decondensation. This strategy was utilized to determine whether any other interphase proteins are also able to disrupt normal mitotic processes, when introduced into the mitotic phase. We found that a chromatin subfraction from bovine liver nuclei induced postmitotic micronuclei formation in a dose-dependent manner when injected into the prometaphase of rat kangaroo kidney epithelial (PtK2) cells. Close observation showed that, in the case of injected mitotic cells, the mitotic spindles were disrupted, chromosomes became scattered throughout the cytoplasm, and actin filaments were organized ectopically. In addition, when the fraction was injected into interphase cells, extra actin filaments were formed and microtubule organization was affected. In order to determine whether the micronuclei formation resulted from the ectopic formation of actin filaments, we examined the effect of the actin polymerization inhibitor, cytochalasin D. The results showed that the drug inhibited micronuclei formation. From these findings, we concluded that this chromatin subfraction contains actin polymerization activity, thus causing the disruption of mitotic spindles.
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Hiroshi Aoto, Hiroko Sasaki, Masaho Ishino, Terukatsu SasakiArticle type: scientific monograph
Subject area: Cell Structure and Function
2002 Volume 27 Issue 1 Pages 47-61
Published: 2002
Released on J-STAGE: April 05, 2002
JOURNAL FREE ACCESSCell adhesion kinase β (CAKβ/PYK2) is a protein-tyrosine kinase of the focal adhesion kinase (FAK) family. Whereas FAK predominantly localizes at focal adhesions, CAK β localizes at the perinuclear region in fibroblasts. Here we expressed in cultured cells two point mutants of CAKβ, P717A and P859A, each of which had lost one of its two PXXP motifs, the ligand sequence for SH3 domains, found at the CAKβ C-terminal region. We observed a remarkable change in the subcellular distribution of the P859A mutant; while that of the P717A mutant was the same as the wild type. The P859A mutant localized exclusively in the cell nucleus in all cell lines examined. Wild-type CAKβ also accumulated in the nucleus when cells were treated with an inhibitor of the nuclear export of proteins. These results indicate that CAK β shuttles between the cytoplasm and the nucleus. On nuclear accumulation of P859A-CAKβ, a CAKβ-binding protein, Hic-5, also accumulated in the nucleus. P859A-CAKβ and co-expressed Hic-5 formed nuclear speckles, in which one other CAK β-binding protein, p130Cas, was also concentrated. These findings on nuclear translocation of CAK β imply that CAKβ may regulate nuclear processes such as transcription, particularly because Hic-5 was recently shown to be a coactivator of nuclear receptors.
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