記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Lamins are thought to direct heterochromatin to the nuclear lamina (NL); however, this function of lamin has not been clearly demonstrated in vivo. To address this, we analyzed (p)olytene chromosome morphology when artificial lamin variants were expressed in Drosophila endoreplicating cells. We found that the CaaX-motif-deleted B-type lamin Dm(0), but not A-type lamin C, was able to form a nuclear envelope-independent layer that was closely associated with chromatin. Other nuclear envelope proteins were not detected in this "ectopic lamina," and the associated chromatin showed a repressive histone modification maker but not a permissive histone modification marker nor RNA polymerase II proteins. Furthermore, deletion of the C-terminal lamin-Ig-fold domain prevents chromatin association with this ectopic lamina. Thus, non-farnesylated B-type lamin Dm(0) can form an ectopic lamina and induce changes to chromatin structure and status inside the interphase nucleus.

DOI： 10.1007/s00412-016-0581-x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Lamins are the major components of nuclear envelope architecture, being required for both the structural and informational roles of the nuclei. Mutations of lamins cause a spectrum of diseases in humans, including muscular dystrophy. We report here that the loss of the A-type lamin gene, lamin C in Drosophila resulted in pupal metamorphic lethality caused by tendon defects, matching the characteristics of human A-type lamin revealed by Emery-Dreifuss muscular dystrophy (EDMD). In tendon cells lacking lamin C activity, overall cell morphology was affected and organization of the spectraplakin family cytoskeletal protein Shortstop which is prominently expressed in tendon cells gradually disintegrated, notably around the nucleus and in a manner correlating well with the degradation of musculature. Furthermore, lamin C null mutants were efficiently rescued by restoring lam in C expression to shortstop-expressing cells, which include tendon cells but exclude skeletal muscle cells. Thus the critical function of A-type lamin C proteins in Drosophila musculature is to maintain proper function and morphology of tendon cells. (C) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ydbio.2012.08.001

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER INC  

To investigate nuclear lamina re-assembly in vivo, Drosophila A-type and B-type lamins were artificially expressed in Drosophila lamin Dm(0) null mutant brain cells. Both exogenous lamin C (A-type) and Dm(0) (B-type) formed sub-layers at the nuclear periphery, and efficiently reverted the abnormal Clustering of the NPC. Lamin C initially appeared where NPCs were clustered, and subsequently extended along the nuclear periphery accompanied by the recovery of the regular distribution of NPCs. In contrast, lamin Dm(0) did not show association with the clustered NPCs during lamina formation and NPC spacing recovered only after completion of a closed lamin Dm(0) layer. Further, when lamin Dm(0) and C were both expressed, they did not co-polymerize, initiating layer formation in separate regions. Thus, A and B-type lamins reveal differing properties during lamina assembly, with A-type having the primary role in organizing NPC distribution. This previously unknown complexity in the assembly of the nuclear lamina could be the basis for intricate nuclear envelope functions. (C) 2008 Published by Elsevier Inc.

DOI： 10.1016/j.yexcr.2008.12.024

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

BAF is a double-stranded DNA binding protein required for proper nuclear morphology and function in Drosophila development. Imaginal discs of Drosophila baf-null mutants were found to exist only in younger larvae as small degenerative tissues. Immunohistochemical analyses showed diffuse lamin distribution, DNA fragmentation, and activation of caspase drICE in these tissues, suggesting that apoptotic events can be induced by the loss of baf. We therefore investigated the fate of BAF after induction of the pro-apoptotic hid transgene, and found that the loss of DNA binding forms of BAF preceded that of non-DNA binding forms of BAF. Furthermore, the DNA binding forms of BAF disappeared from nuclei before DNA fragmentation and NPC clustering were detected, showing that the loss of BAF occurs at the initial stages of nuclear apoptosis. This BAF loss was not detected before drICE activation and was inhibited by Ac-DEVD-CHO caspase inhibitors. In summary, BAF disappears at an early stage due to caspase activity when apoptosis is induced by hid, and its depletion in mutants is sufficient in itself to induce cell death, suggesting it is an apoptotic mediator. (C) 2007 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jsb.2007.07.010

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER INC  

The mechanism underlying targeting of the nuclear membrane to chromatin at the end of mitosis was studied using an in vitro cell-free system comprising Xenopus egg membrane and cytosol fractions, and sperm chromatin. The mitotic phase membrane, which was separated from a mitotic phase extract of Xenopus eggs and could not bind to chromatin, became able to bind to chromatin on pretreatment with a synthetic phase cytosol fraction of Xenopus eggs. When the cytosol fraction was depleted of protein phosphatase 1 (PP1) with anti-Xenopus PP1-gamma 1 antibodies, this ability was lost. The addition of recombinant xPP1 gamma 1 to the PP1-depleted cytosol fraction restored the ability. These and other results suggested that dephosphorylation of mitotic phosphorylation sites on membranes by PP1 in the synthetic phase cytosol fraction promoted targeting of the membranes to chromatin. On the other hand, a fragment containing the chromatin-binding domain of lamin B receptor (LBR) but not emerin inhibited targeting of membrane vesicles. It was also shown that PP1 dephosphorylates a phosphate group(s) responsible for regulation of the binding of LBR to chromatin. A possible mechanism involving PP1 and LBR for the regulation of nuclear membrane targeting to chromatin was discussed. (c) 2007 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.yexcr.2007.03.015

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記述言語：日本語   出版者・発行元：日本プロテオーム学会（日本ヒトプロテオーム機構）  

DOI： 10.14889/jhupo.2012.0.184.0

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記述言語：日本語   出版者・発行元：日本プロテオーム学会（日本ヒトプロテオーム機構）  

細胞核は、"構造"と"機能"が密接に関わり合ったダイナミックな構造体である。その内部には、核小体や核スペックルなどの核内構造体が存在し、プロテオーム解析によってそれらの構成因子が解析されてきたが、これまでの研究では核構造全体に真に重要な難溶性タンパク質の同定が見逃されているという問題がある。そこで、細胞核機能をより理解するために、細胞核構造内の難溶性である核マトリックス画分をプロテオーム解析することによって細胞核構造基盤分子の検索を行った。<BR> 具体的には、HeLa細胞を塩、界面活性剤、DNaseで処理したときに難溶性画分として得られた核マトリックス画分を、(1)難溶性画分タンパク質分離クロマト系とSDS-PAGEを組み合わせた分離・精製を用いたpeptide mass fingerprint (PMF)法、(2)SDS-PAGEとnanoLC-MS/MSを用いたpeptide sequence tag (PST)法、という2つの方法で核マトリックス画分のプロテオーム解析を行った。最初に、HeLa細胞から調製した核マトリックス画分タンパク質を一次元目に60% ギ酸中で逆相HPLCにより、二次元目に濃度勾配ゲルを用いたSDS-PAGEで分離した。それをCBB染色した結果、138種類のタンパク質バンドが検出され、それらすべてをトリプシンでゲル内消化後、PMF法により、85種類のタンパク質を同定した。この中には、細胞内局在が未知である新規タンパク質が6種類、機能未知のタンパク質が8種類含まれていた。また、さらに網羅的に解析を行うために、核マトリックス画分をSDS-PAGEで分離・CBB染色後、ゲルを29断片にスライスし、トリプシン消化後、ペプチドをnanoLC-MS/MSで分析した。その結果、PST法により、334種類のタンパク質を同定し、この中には、細胞内局在が未知である新規タンパク質が40種類、機能未知のタンパク質が76種類含まれていた。今回の解析で、難溶性画分として得られた核マトリックス画分内に、核機能に関与するタンパク質が多く含まれていることが明らかになったことから、細胞核の機能を理解するために有用な情報を得ることができた。<BR> 新規タンパク質群に関しては、現在GFP融合タンパク質発現ベクターを構築し、細胞核内での詳細な局在の動態を明らかにする解析を進めている。

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記述言語：日本語   出版者・発行元：共立出版  

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記述言語：日本語   出版者・発行元：共立出版  

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記述言語：日本語   出版者・発行元：共立出版  

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