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Experimental Genetics Group
J Biol Chem. 2003 Nov 7;278(45):44393-9. Ris L1, Dewachter I2, Reversé D1, Godaux E1, Van Leuven F2. 1Laboratory of Neuroscience, University of Mons-Hainaut, Mons, Belgium. 2Experimental Genetics Group, Department of Human Genetics, K.U.Leuven, Leuven, Belgium. Presenilins, whose mutant forms are the most common cause of early onset familial Alzheimer's disease, are involved in two very distinct processes: (i) proteolytic activity as gamma-secretase acting on amyloid precursor protein to produce amyloid peptides and (ii) storage of Ca2+ in the endoplasmic reticulum (ER). In particular, absence of presenilin-1 (PS1) was claimed to potentiate capacitative calcium entry (CCE), i.e. the mechanism of replenishment of ER Ca2+ stores. However, until now, evidence in favor of the latter role has been obtained only in isolated or cultured cells and not on neurons in situ. Here, we studied the strength of the synapses between Schaffer's collaterals and CA1 neurons in hippocampal slices when they were submitted first to Ca(2+)-free medium containing thapsigargin and subsequently to normal artificial cerebrospinal fluid, a procedure known to trigger CCE. We demonstrate that Ca2+ influx via the CCE mechanism is sufficient to trigger robust long term potentiation of the synapses in hippocampal slices from transgenic mice with a postnatal, neuron-specific ablation of PS1, but remarkably not from wild-type mice. Our data establish for the first time in neurons confined in normal neuronal networks that PS1 acts on the refilling mechanism of ER Ca2+ stores.  FULL TEXT |
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