Spine structural change - Nothing to do with physiology ?
Today's journal club was about Shrinkage of dendritic spines associated with LTD, Neuron. 2004 Dec 2;44(5):749-57. from Poo's lab.
Blocking of cofilin phosphorylation blocks spine shrinkage without affecting LTD, and blocking PP1 blocks LTD without blocking spine shrinkage. Both are blocked by calcineurin blocker. These suggest the LTD inducing stimulation activates the calcineurin pathway, and the pathway branchs out to produce two different phenomena, LTD and spine shrinkage.
Clearly spine structural change is NOT required by the change in synaptic strength. This is probably the same for LTP and spine enlargement: I heard from several guys that the washout by patch-clamping often blocks selectively the spine enlargement but not LTP.
Then why the spine structure changes ? One possibility is the structural change is just a side effect: because the actin polymerization is regulated by a balance of kinase/phosphatase activity, LTP/LTD inducing stimulation, which changes this balance, can change the sturcture of spines. Or, maybe this is important for late-phase LTP: larger spines can contain more resource to maintain LTP.
Blocking of cofilin phosphorylation blocks spine shrinkage without affecting LTD, and blocking PP1 blocks LTD without blocking spine shrinkage. Both are blocked by calcineurin blocker. These suggest the LTD inducing stimulation activates the calcineurin pathway, and the pathway branchs out to produce two different phenomena, LTD and spine shrinkage.
Clearly spine structural change is NOT required by the change in synaptic strength. This is probably the same for LTP and spine enlargement: I heard from several guys that the washout by patch-clamping often blocks selectively the spine enlargement but not LTP.
Then why the spine structure changes ? One possibility is the structural change is just a side effect: because the actin polymerization is regulated by a balance of kinase/phosphatase activity, LTP/LTD inducing stimulation, which changes this balance, can change the sturcture of spines. Or, maybe this is important for late-phase LTP: larger spines can contain more resource to maintain LTP.
posted by Ryohei at 9:20 AM
<< Home