Analysis of gene expression changes associated with long-lasting synaptic enhancement in hippocampal slice cultures after repetitive exposures to glutamate.
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.
Kawaai
Katsuhiro
K
Department of Chemistry and Biological Science, School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
Tominaga-Yoshino
Keiko
K
Urakubo
Tomoyoshi
T
Taniguchi
Naoko
N
Kondoh
Yasumitsu
Y
Tashiro
Hideo
H
Ogura
Akihiko
A
Tashiro
Tomoko
T
D000199:Actins / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D051338:Cofilin 1 / Q000235:genetics / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D018698:Glutamic Acid / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism; D050857:Synaptotagmins / Q000378:metabolism; D013997:Time Factors
D000199:Actins; D019208:Brain-Derived Neurotrophic Factor; C495812:Cfl1 protein, rat; D051338:Cofilin 1; C578937:Grm5 protein, rat; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; C494294:Syt4 protein, rat; D050857:Synaptotagmins; D018698:Glutamic Acid