Regulation of excitatory transmission at hippocampal synapses by calbindin D28k.

Abstract

Calbindin D28k is a high-affinity Ca2+-binding protein (CABP) found to be widely distributed in the nervous system where it has been shown to modulate Ca2+ signaling (1). Light and electron microscopy have clearly demonstrated the existence of calbindin D28k in presynaptic nerve terminals, where it exists in up to millimolar concentrations (2-4). It is therefore tempting to speculate that calbindin D28k also plays a role in modulating synaptic physiology. However, no direct experimental evidence is presently available to validate such a contention.Several techniques have been developed for the overexpression of proteins in cells. Unfortunately, many of these suffer from very low efficiency or require the exogenous DNA to integrate into the genome of a replicating target cell. Recently, several groups have used adenoviruses as expression vectors because these vectors do not require host cell replication and give rise to highly efficient gene expression in host cells (5, 6). Several other advantages of using adenoviruses include the capacity to propagate the virus to high titers and the large amount of exogenous DNA that may be inserted into the viral vector (-7 kb if the El and E3 regions of the viral genome are deleted).In vivo injection of a recombinant adenovirus expressing 13-galactosidase (LacZ gene) into the rat hippocampus and substantia nigra resulted in widespread expression of LacZ in neuronal and nonneuronal cells (5). In addition, infecting cultured neurons with a recombinant adenovirus containing the ,B-galactosidase gene resulted in 80-100% of the cells expressing the protein. Moreover, f3-galactosidase expression appeared to be sustained for at least 1 month after infection without any indication of morphological damage (7).In the present study, we have constructed a replicationdefective adenovirus containing the calbindin D28k cDNAThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.under the control of the elongation factor la (EF-la) promoter and the 4F2HC enhancer (8). We Louis). A blunt-endedBan II/Spe I fragment of calbindin D28k cDNA was inserted into the EcoRV site of transfer vector pAdKN-downstream from EF-la promoter and upstream from the cellular heavychain enhancer (4F2) and bovine growth hormone polyadenylation site (pA+). The pAdKN plasmid also contained 0-1 and 9-16 map units of DNA sequence of adenovirus 5.To construct the recombinant adenovirus AdCABP-1, the plasmid pAdKN-CABP-1 was first linearized by digesting it with Nhe I, while Xba I and Cla I were used to digest adenovirus 5 (sub 360) DNA. The linear DNA was then cotransfected into human embryonic kidney cells (HEK 293 cells)-a trans-complementing cell line for El function (9)-by the calcium phosphate precipitation method. The recombinant AdCABP-1 was plaque purified three times to isolate a homogeneous population of the virus. The virus was further purified...

Expression of 5-HT7 receptor mRNA in the hamster brain: Effect of aging and association with calbindin-D28K expression

“…It is interesting to note that immunohistochemical studies have shown that another serotonin receptor subtype, the 5-HT 1A receptor, is co-localized with calbindin in several rat brain regions, including the hippocampus, the thalamus and the septum (Aznar et al, 2003). As well as modulating photic phase shifts (Hamada et al, 2003), as described above, calbindin has been implicated in several other functions, including spatial memory, long-term potentiation in the hippocampus, synaptic plasticity, and either neuroprotection or enhanced vulnerability to neurodegeneration (Jouvenceau et al, 1999;Chard et al, 1995;Molinari et al, 1996;Nagerl et al, 2000). Some of these functions, such as memory, long-term potentiation, and synaptic plasticity are also modulated by 5-HT 7 receptors (Perez-Garcia et al, 2006;PerezGarcia and Meneses, 2005;Roberts et al, 2004;Kvachnina et al, 2005).…”

Calbindin in Cerebellar Purkinje Cells Is a Critical Determinant of the Precision of Motor Coordination

“…It has been demonstrated that another calcium-binding protein, parvalbumin, regulates the paired-pulse ratio through modulation of transmitter release (Caillard et al, 2000). Furthermore, overexpression or deletion of calbindin in hippocampal neurons resulted in the selective modification of posttetanic potentiation (Chard et al, 1995;Klapstein et al, 1998), presumably by changing the global Ca 2ϩ concentration increase in presynaptic terminals necessary for mediating potentiation of neurotransmitter release on a second to minute time scale.…”

“…However, despite the suggestion of an involvement of Purkinje cells, it remained unclear which cell types were responsible for the behavioral phenotype, because calbindin is expressed by many types of neurons throughout the brain (Celio, 1990). Even in the cerebellum, calbindin is expressed abundantly not only in Purkinje cells but also in climbing fibers (Celio, 1990;Scotti, 1995), and previous studies demonstrated that Ca 2ϩ -binding proteins influence presynaptic transmitter release (Chard et al, 1995;Klapstein et al, 1998;Caillard et al, 2000). Finally, it was not tested whether the calbindin-mediated change in Ca 2ϩ signaling affected cerebellar LTD. To study the specific role of calbindin in a single defined neuronal cell type, we generated a Purkinje cell-specific calbindin null mutant mouse strain and performed an analysis on the cellular and behavioral level.…”

Role of the calcium-binding protein parvalbumin in short-term synaptic plasticity

“…Calbindin D 28k , which is a significantly faster buffer than PV (38), but still has a binding rate for calcium about 10-times smaller than 1,2-bis(2-aminophenoxy)ethane-N,N,NЈ,NЈ-tetraacetic acid (BAPTA), could act as a slow buffer or as a fast buffer depending on the preparation and the stimulation protocol. In hippocampal neurons in culture, addition of calbindin reduces posttetanic potentiation (39), and, in these conditions, calbindin acts like a slow buffer. However, at hippocampal mossy fiber synapses, removal of calbindin leads to reduced facilitation, so that here calbindin appears to act as a fast buffer (40).…”