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<84th RIKEN BSI Invited Seminar Series>

"14:00-15:30 May 26 (Monday)"
1F Seminar Room&s_comma; BSI Central Bldg.
RIKEN Wako Campus
Access to RIKEN BSI;
(English) http://www.brain.riken.jp/en/visiting/files/visitingbsi.pdf
(Japanese) http://www.brain.riken.jp/jp/visiting/files/visitingbsi.pdf

Invited Lecturer:
Prof. Michael V.L. Bennett&s_comma; Department of Neuroscience Albert Einstein College of Medicine&s_comma; U.S.A.

Title:
Connexin hemichannels: a new signaling channel in the plasma membrane

Abstract:
Vertebrate gap junctions are formed of onnexins&s_comma; a protein family of ~20 members in humans. Connexin monomers&s_comma; which are integral
membrane proteins&s_comma; are assembled into hexamers&s_comma; or “hemichannels”&s_comma; in the endoplasmic reticulum&s_comma; Golgi apparatus or a post-Golgi
compartment&s_comma; and vesicles containing hemichannels are inserted into the surface membrane. These hemichannels then diffuse in the
plane of the membrane to find a hemichannel in an apposed cell&s_comma; often at the edge of a preexisting junction. The two hemichannels
then dock with each other to form the complete cell-cell channel. Because of the relatively large size of the cell-cell channel in
terms of conductance and permeability&s_comma; it was thought that hemichannels would not open until docking&s_comma; because an open hemichannel
would allow excessive influx of Ca2+ and Na+ and loss of K+ and metabolites. Now it is known that hemichannels can open&s_comma; although
generally with low probability&s_comma; under both physiological and pathological conditions. As a normal response&s_comma; hemichannels can mediate
propagation of Ca+ waves by release of ATP&s_comma; which acts through purinergic receptors to cause further release of ATP. (Cell-cell
channels also can mediate Ca+ waves by diffusion of IP3; distinguishing the two modes requires caution&s_comma; because gap junction
blockers also block hemichannels.) In pathological conditions&s_comma; ATP released through hemichannels can aggravate inflammation by
recruitment of microglia. Hemichannels can also release glutamate and increase excitotoxic cell death. Intra- and extracellular
signals modulating hemichannel gating are just being discovered and have implications for local modulation of synaptic transmission
and post-ischemic neurodegeneration.
When copied and pasted back into Word&s_comma; the superscripts come out fine.

*No registration or entrance fee required.
Seminar will be held in English.

Host Labs:
Dr. Tomomi Shimogori&s_comma; Shimogori Research Unit (tshimogori@brain.riken.jp&s_comma; 048-462-1111 ext. 7267)




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