Analysis of gene expression changes associated with long‐lasting synaptic enhancement in hippocampal slice cultures after repetitive exposures to glutamate

Abstract

We have previously shown that repetitive exposures to glutamate (100 muM, 3 min, three times at 24-hr intervals) induced a long-lasting synaptic enhancement accompanied by synaptogenesis in rat hippocampal slice cultures, a phenomenon termed RISE (for repetitive LTP-induced synaptic enhancement). To investigate the molecular mechanisms underlying RISE, we first analyzed the time course of gene expression changes between 4 hr and 12 days after repetitive stimulation using an original oligonucleotide microarray: "synaptoarray." The results demonstrated that changes in the expression of synapse-related genes were induced in two time phases, an early phase of 24-96 hr and a late phase of 6-12 days after the third stimulation. Comprehensive screening at 48 hr after the third stimulation using commercially available high-density microarrays provided candidate genes responsible for RISE. From real-time PCR analysis of these and related genes, two categories of genes were identified, 1) genes previously reported to be induced by physiological as well as epileptic activity (bdnf, grm5, rgs2, syt4, ania4/carp/dclk) and 2) genes involved in cofilin-based regulation of actin filament dynamics (ywhaz, ssh1l, pak4, limk1, cfl). In the first category, synaptotagmin 4 showed a third stimulation-specific up-regulation also at the protein level. Five genes in the second category were coordinately up-regulated by the second stimulation, resulting in a decrease in cofilin phosphorylation and an enhancement of actin filament dynamics. In contrast, after the third stimulation, they were differentially regulated to increase cofilin phosphorylation and enhance actin polymerization, which may be a key step leading to the establishment of RISE.

Early Phase of Plasticity-Related Gene Regulation and SRF Dependent Transcription in the Hippocampus

“…Previous studies [50] [163] [164] have already suggested that, following episodes of synaptic activity or during synaptic plasticity processes, the induced immediate-early-genes (IEGs) are characterized by different up-regulation dynamics: nonetheless, the time-course data collected so far in the literature is mainly obtained by microarray analysis, such as [7] [165], and not by a reliable and accurate RT-PCR analysis: more precisely, the information currently available is limited to time-courses with low temporal resolution, i.e. a few time points, and/or concerning a reduced number of genes, such as [15] [18] [19].…”

Latent process genes for cell differentiation are common decoders of neurite extension length

“…Carp (Ania-4) has been reported to be involved in apoptosis and tubulin polymerization in vitro (Schenk et al, 2007) and in seizures and long-term potentiation in vivo (Schenk et al, 2011;Vreugdenhil et al, 1999;Wibrand et al, 2006). Thus, the DCLK1 proteins might direct the latent process of neural cell differentiation by controlling tubulin formation or by modulating cell viability and subsequent synaptic plasticity (Kawaai et al, 2010;Shu et al, 2006;Vreugdenhil et al, 2007). Expression of Serpinb1a has also been reported to be induced in response to NGF-and PACAP-induced cell differentiation in PC12 cells (Ravni et al, 2008).…”

Activation of tachykinin, neurokinin 3 receptors affects chromatin structure and gene expression by means of histone acetylation

“…Interestingly, hypothalamic magnocellular neurons express VEGF , and VEGF expression in these neurons is increased in response to hyperosmolarity or dehydration [4]. Similar to VEGA, YWHAZ expression affects neural function [36], and YWHAZ message and protein increase in hypothalamic neurons in response to hyperosmolarity resulting from dehydration [20]. The neurotransmitter mediators of this change in expression were not identified.…”