Spino-dendritic cross-talk in rodent Purkinje neurons mediated by endogenous Ca2+-binding proteins.
The range of actions of the second messenger Ca(2+) is a key determinant of neuronal excitability and plasticity. For dendritic spines, there is on-going debate regarding how diffusional efflux of Ca(2+) affects spine signalling. However, the consequences of spino-dendritic coupling for dendritic Ca(2+) homeostasis and downstream signalling cascades have not been explored to date. We addressed this question by four-dimensional computer simulations, which were based on Ca(2+)-imaging data from mice that either express or lack distinct endogenous Ca(2+)-binding proteins. Our simulations revealed that single active spines do not affect dendritic Ca(2+) signalling. Neighbouring, coactive spines, however, induce sizeable increases in dendritic [Ca(2+)](i) when they process slow synaptic Ca(2+) signals, such as those implicated in the induction of long-term plasticity. This spino-dendritic coupling is mediated by buffered diffusion, specifically by diffusing calbindin-bound Ca(2+). This represents a central mechanism for activating calmodulin in dendritic shafts and therefore a novel form of signal integration in spiny dendrites.
Schmidt
Hartmut
H
Carl-Ludwig-Institut für Physiologie, Liebigstrasse 27, 04103 Leipzig, Germany. hartmut.schmidt@medizin.uni-leipzig.de
Kunerth
Svenja
S
Wilms
Christian
C
Strotmann
Rainer
R
Eilers
Jens
J
D000818:Animals; D064026:Calbindins; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D003198:Computer Simulation; D049229:Dendritic Spines / Q000378:metabolism / Q000502:physiology*; D004058:Diffusion; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D008959:Models, Neurological; D009473:Neuronal Plasticity; D010320:Parvalbumins / Q000378:metabolism; D011689:Purkinje Cells / Q000378:metabolism / Q000502:physiology*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D009435:Synaptic Transmission
D064026:Calbindins; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D002118:Calcium