3月10日(木)「Ion Channels Activated by Mechanical Forces in Bacterial and Eukaryotic Cells」講師:曽我部正博 先生


先導研客員教授 曽我部正博先生の講演会を開催いたします。

なお、本講演はワシントン大学名誉教授Allan Hoffman先生の特別講演会とのジョイントセミナーの前半として行います。ジョイントセミナーのお知らせは、Hoffman先生のホストをされている田中賢先生から改めてアナウンスがございます。多数、ご来聴賜りますようご案内申し上げます。   木戸秋 悟

 日 時 : 3月10日(木)14:00~15:30
 場 所 : 先導研伊都地区CE41 第一セミナー室A・B
 講 師 : 曽我部正博 先生(名古屋大学名誉教授) 
 演 題 : 「Ion Channels Activated by Mechanical Forces in Bacterial and Eukaryotic Cells」

  Masahiro Sokabe1,2
    1 Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya, Japan
    2 Mechanobiology Institute, National University of Singapore, Singapore

Since the first discovery of mechanosensitive ion channel (MSC) in non-sensory cells in 1984, a variety of MSCs have been identified both in prokaryotic and eukaryotic cells. One of the central issues concerning MSCs is to understand the molecular and biophysical mechanisms of how mechanical forces activate/open MSCs. It has been well established that prokaryotic (mostly bacterial) MSCs are activated exclusively by membrane tension. Thus the problem to be solved with prokaryotic MSCs is the mechanisms how the MSC proteins receive tensile forces from the lipid bilayer and utilize them for channel opening. On the other hand, the activation of many eukaryotic MSCs crucially depends on tension in the actin cytoskeleton. By using the actin cytoskeleton as a force sensing antenna, eukaryotic MSCs have obtained sophisticated functions such as remote force sensing and force-direction sensing, which bacterial MSCs do not have. Actin cytoskeletons also give eukaryotic MSCs an interesting and important function called “active touch sensing”, by which cells can sense rigidity of their substrates. The contractile actin cytoskeleton stress fiber (SF), anchors its each end to a focal adhesion (FA) and pulls the substrate to generate substrate-rigidity-dependent stresses in the FA. It has been found that those stresses are sensed by some Ca2+-permeable MSCs existing in the vicinity of FAs, thus the MSCs work as a substrate rigidity sensor that can transduce the rigidity into intracellular Ca2+ levels. Two topics on the molecular and biophysical mechanisms underlying the MSC activation process will be presented: 1) structure-function in bacterial MSC activation at the atomic level, and 2) roles of actin cytoskeletons in the activation of eukaryotic MSCs.  

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