Roles of FoxP3-positive Regulatory T Cells in Lymphoid Follicle Formation Associated with Lung Squamous Cell Carcinoma

Background：We previously reported that lymphoid follicle formation by tumor infiltrating lymphocytes（TILs）is a negative predictor of prognosis in patients with lung squamous cell carcinoma（SCC）following surgery. However, the roles of FoxP3⁺/CD4⁺/CD25⁺-regulatory T cells（Tregs）in formation of lymphoid follicles as well as survival remain unclear.Methods：Specimens obtained from patients during resection of lung SCC were examined for lymphoid follicle formation and subjected to immunohistochemistry analysis for the presence of TILs.Results：The appearance of Tregs was correlated with lymphoid follicle formation（p＝0.001）. Univariate analysis also showed that Tregs tended to be correlated with overall survival（p＝0.097）, whereas multivariate analysis revealed that lymphoid follicle formation（p＝0.042）and pleural invasion（p＝0.031）were independent prognostic factors related to overall survival, while the appearance of Tregs was not.Conclusion：Treg appearance was correlated with lymphoid follicle formation. That lymphoid follicle formation, rather than appearance of Tregs, is a predictor of patients survival following surgery for lung SCC

Topoisomerase II, scaffold component, promotes chromatin compaction in vitro in a linker-histone H1-dependent manner

TopoisomeraseII (Topo II) is a major component of chromosomal scaffolds and essential for mitotic chromosome condensation, but the mechanism of this action remains unknown. Here, we used an in vitro chromatin reconstitution system in combination with atomic force and fluorescence microscopic analyses to determine how Topo II affects chromosomal structure. Topo II bound to bare DNA and clamped the two DNA strands together, even in the absence of ATP. In addition, Topo II promoted chromatin compaction in a manner dependent on histone H1 but independent of ATP. Histone H1-induced 30-nm chromatin fibers were converted into a large complex by Topo II. Fluorescence microscopic analysis of the Brownian motion of chromatin stained with 4′,6-diamidino-2-phenylindole showed that the reconstituted chromatin became larger following the addition of Topo II in the presence but not the absence of histone H1. Based on these findings, we propose that chromatin packing is triggered by histone H1-dependent, Topo II-mediated clamping of DNA strands

DNA ノ カイソウテキ コウジ コウゾウ ニ タイスル ブツリテキ アプローチ

京都大学0048新制・課程博士博士(理学)甲第14364号理博第3361号新制||理||1494(附属図書館)UT51-2009-D76京都大学大学院理学研究科物理学・宇宙物理学専攻(主査)教授 吉川 研一, 教授 小貫 明, 教授 山本 潤学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

The hierarchical structure of chromatin : Nucleosomal array reconstitution with ring and linear DNA(Knots and soft-matter physics: Topology of polymers and related topics in physics, mathematics and biology)

この論文は国立情報学研究所の電子図書館事業により電子化されました。真核生物で見られる階層的な折りたたみの基本構造としてヌクレオソーム(長さ50nmのDNAがコアヒストンと呼ばれる直径7nmのタンパクに巻きついた構造)が知られている。DNAの長さ、ねじれ、大域的な構造(環状等)がヌクレオソーム形成に与える影響は未だ十分に理解されていない。本研究ではDNAの両端がつながっている環状構造がヌクレオソーム形成に与える影響を明らかにするために、全長1マイクロメートルの線状・環状DNAを用いて再構成を行い、その効率とヌクレオソーム間相互作用の検討を行った。その結果、環状のDNAを用いた場合の方が環状構造に由来して再構成の効率が高くなることが明らかになった

5. Single-chain Characteristics in Giant DNA : Larger Hydrodynamic Radius in Circular than that in Linear(poster presentation,Soft Matter as Structured Materials)

この論文は国立情報学研究所の電子図書館事業により電子化されました。環状高分子の広がり(慣性半径や末端間距離の2乗平均)が同じ全長の線状高分子のものより小さいことはよく知られている。しかし環状高分子の合成は難しく、実験的な検証が困難なため環状高分子に関しては不明な点が多い。一方天然高分子DNAでは生体内にウィルスのプラスミドなど環状DNAが存在し、制限酵素を用いて一箇所切断することにより、容易に全長が単分散な環状および線状高分子を得ることができる。そこで本研究では106キロ塩基対(全長約36μm)の線状および環状DNAの流体力学的半径を蛍光顕微鏡を用いた単分子直接観察によって測定した。その結果、長鎖環状DNAの流体力学的半径は線状のものよりも25%以上大きいことを見出した

Hydrodynamic radius of circular DNA is larger than that of linear DNA

It is generally accepted that linear polymers are larger, such as with regard to the end-to-end distance and gyration radius, than the corresponding circular polymers. We measured the Brownian motion of individual linear and circular 106-kbp DNA molecules using fluorescence microscopy. Unexpectedly, the hydrodynamic radius of linear DNA was markedly smaller than that of circular DNA

Removal of histone tails from nucleosome dissects the physical mechanisms of salt-induced aggregation, linker histone H1-induced compaction, and 30-nm fiber formation of the nucleosome array

In order to reveal the roles of histone tails in the formation of higher-order chromatin structures, we employed atomic force microscopy (AFM), and an in vitro reconstitution system to examine the properties of reconstituted chromatin composed of tail-less histones and a long DNA (106-kb plasmid) template. The tail-less nucleosomes did not aggregate at high salt concentrations or with an excess amount of core histones, in contrast with the behavior of nucleosomal arrays composed of nucleosomes containing normal, N-terminal tails. Analysis of our nucleosome distributions reveals that the attractive interaction between tail-less nucleosomes is weakened. Addition of linker histone H1 into the tail-less nucleosomal array failed to promote the formation of 30 nm chromatin fibers that are usually formed in the normal nucleosomal array. These results demonstrate that the attractive interaction between nucleosomes via histone tails plays a critical role in the formation of the uniform 30-nm chromatin fiber