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SUMMARY:Nucleocytoplasmic Transport Machinery and Pathways: Cell Cycle Reg
 ulation and Stress Response - Naoko Imamoto\, Cellular Dynamics Laboratory
 \, RIKEN ASI
DTSTART:20101115T140000Z
DTEND:20101115T160000Z
UID:TALK27762@talks.cam.ac.uk
CONTACT:Scientific Meetings Co-ordinator
DESCRIPTION:　Major interest of our group is to understand function and s
 tructure of nuclear pore complexes (NPCs). NPC is a large protein assembly
  embedded in the nuclear envelope\, which provides a sole pathway for mole
 cular trafficking between the nucleus and the cytoplasm. In the present ta
 lk\, I will provide two topics of our recent results: one on the regulatio
 n of interphase NPC assembly\, and second on the novel transport pathway t
 hat operates during heat-shock stress response.   \n　NPCs are assembled 
 twice during the cell cycle in metazoa: end of mitosis (post-mitotic NPC f
 ormation)\, and during interphase. Post-mitotic NPC assembly takes place o
 n mitotic chromosomes\, whereas interphase NPC assembly takes place on the
  double lipid bilayer of the nuclear envelope. Because it is more difficul
 t to analyze\, less is known about interphase NPC assembly compared to pos
 t mitotic NPC assembly. We have developed a system to visualize interphase
  NPC assembly based on cell-fusion methods and photobleaching. Combining t
 hese visualization techniques with siRNA has allowed us to identify cyclin
 -dependent kinases (Cdks) as an important regulator of interphase NPC asse
 mbly. Interestingly\, activity of Cdks is not required for the post-mitoti
 c NPC assembly. The issue of target(s) of Cdks\, which may explain the dif
 ferent mechanisms underlying between interphase and post-mitotic NPC assem
 bly will be discussed.    \n   During the heat-shock stress response\, con
 ventional nucleocytoplasmic transport is down-regulated\, possibly due to 
 defects in small GTPase Ran system\, while the nuclear import of molecular
  chaperones such as hsp70s are up-regulated. Using a transport-reconstitut
 ed system\, we found that the heat-shock-induced nuclear import of hsp70s 
 is mediated by a novel receptor\, which does not belong to well-characteri
 zed members of the importin β superfamily. In living cells\, depletion of
  this molecule potently inhibits heat-shock-induced nuclear migration of h
 sp70s\, reduces cell viability after heat-shock\, and causes significant d
 elay in attenuation of heat-shock response. Taken together\, our data show
  a novel nuclear import receptor for hsp70s is required for protecting cel
 l damages from the stress.  \n
LOCATION:Max Perutz Lecture Theatre\, Medical Research Council (MRC) (MRC 
 Laboratory of Molecular Biol
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