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My lab:
This talk by Leonard Kaczmarek was all about ion channels. The model Leonard works on are the bag cells neurons in Aplysia. These bag cell neurons regulate reproductive behaviors via multiple neuropeptides. These neuropeptides get released during an afterdischarge which can last for up to 30 minutes after the initial brief stimulation. The details of the channel modifications leading to the brief hyperpolarisation after the initial stimulus and the prolonged afterdischarge are well-characterized. For instance, Protein Kinase A and PKC each modify several Calcium and Potassium channels to produce spike broadening.
During the afterdischarge, the Kv2.1 Potassium channels aggregate into donut-shaped clusters. The interesting thing is: people have seen this clustering in hippocampal neurons in rats/mice, but nobody knows what the function of the clusters may be.
Leonard also showed us beautiful pictures of bag cell growth cones and how different kinases lead to differential insertion of channels into the plasma membrane of the cone. For example, activation of PKC recruits Cav2.1 channels into the membrane.
Finally, we learned about two sodium activated potassium channels, 'slick' and 'slack', which are also present in bag cell neurons. Slack binds Fragile X mental retardation protein (FMRP), which in turn binds mRNA. Apparently, this FMRP binding to slack is related to protein synthesis which is triggered by neuronal activity. Confirming this hypothesis, sodium injection stimulates neuropeptide translation in bag cell neurons.
Posted on Thursday 07 June 2007 - 00:18:17 comment: 0

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