Nature Genetics
30, 416 - 420 (2002)
Published online: 4 March 2002; | doi:10.1038/ng859
c-fos regulates neuronal excitability and survivalJianhua Zhang1, Dongsheng Zhang1, Jill Slane McQuade1, Michael Behbehani2, Joe Z. Tsien3
& Ming Xu11 Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA. 2 Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA. 3 Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
Correspondence should be addressed to Ming Xu ming.xu@uc.eduExcitotoxicity is a process in which glutamate or other excitatory amino acids induce neuronal cell death. Accumulating evidence suggests that excitotoxicity may contribute to human neuronal cell loss caused by acute insults and chronic degeneration in the central nervous system1,
2,
3,
4. The immediate early gene (IEG) c-fos encodes a transcription factor5,
6. The c-Fos proteins form heterodimers with Jun family proteins, and the resulting AP-1 complexes regulate transcription by binding to the AP-1 sequence found in many cellular genes7,
8,
9. Emerging evidence suggests that c-fos is essential in regulating neuronal cell survival versus death10. Although c-fos is induced by neuronal activity, including kainic acid-induced seizures11,
12,
13,
14, whether and how c-fos is involved in excitotoxicity is still unknown. To address this issue, we generated a mouse in which c-fos expression is largely eliminated in the hippocampus. We found that these mutant mice have more severe kainic acid−induced seizures, increased neuronal excitability and neuronal cell death, compared with control mice. Moreover, c-Fos regulates the expression of the kainic acid receptor GluR6 and brain-derived neurotrophic factor (BDNF), both in vivo and in vitro. Our results suggest that c-fos is a genetic regulator for cellular mechanisms mediating neuronal excitability and survival.
We made a mouse with the loxP-c-fos-loxP insertion (designated as f/fc-fos; Fig. 1a,b). We then crossed the f/fc-fos mouse with a T50 CaMKII -cre transgenic mouse15. Southern blotting identified mice carrying both the homozygous f/fc-fos gene (Fig. 1b) and the cre transgene (f/fc-fos-cre; Fig. 1c).
 | | Figure 1. Generation of f/fc-fos-cre mice. | | |  | a, The c-fos genomic DNA locus, the targeting vector, the floxed c-fos gene locus, and the 5' and 3' hybridization probes. The neor transcription direction is the same as that of the c-fos. Open boxes represent c-fos exons; black arrows indicate the loxP sites. Restriction sites shown: Bg, BglII; Cl, ClaI; Sp, SpeI. b, Identification of the f/fc-fos mice. Tail DNA from two litters of heterozygous intercross was digested with BglII, electrophoretically separated, transferred onto membranes and hybridized with a 3' probe for c-fos. c, Identification of the f/fc-fos-cre mice by Southern hybridization of the same litters of mice as in b, using a cre-specific probe.
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We quantified both basal and induced c-fos expression in the hippocampus and dentate of wildtype, f/fc-fos and f/fc-fos-cre mice before and after injections of kainic acid. Kainic acid is a glutamate analog that elicits seizures by directly stimulating glutamate receptors (GluRs) and indirectly increasing the release of excitatory amino acids from nerve terminals13,
14. In situ hybridization demonstrates that whereas basal levels of c-fos are very low and comparable in nontreated wildtype and f/fc-fos mice, equal levels of c-fos induction are seen in pyramidal neurons in CA3, CA2 and CA1 regions of the hippocampus and in granule cells in the dentate gyrus, in both genotypes, upon treatment with kainic acid (Fig. 2a−d,g). In contrast, f/fc-fos-cre mice at ten weeks of age or older have virtually no basal c-fos expression and at least a 95% reduction in c-fos induction in the CA3, CA2 and CA1 regions and a 70% reduction in the dentate, compared with wildtype and f/fc-fos mice (Fig. 2a−g) and with cre transgenic mice (data not shown). Notably, there seems to be equal c-fos induction by kainic acid in other brain regions, including the entorhinal cortex, median eminence and cortex in f/fc-fos-cre, f/fc-fos and wildtype mice (see Web Fig. 1a−j on the supplementary information page of Nature Genetics online). Immunostaining confirms the in situ hybridization results (Fig. 2h−m). f/fc-fos−cre mice show no obvious deficiencies in brain development (Web Fig. 2a−i).
| | Figure 2. Basal expression and induction of c-fos is significantly reduced in the hippocampus in f/fc-fos−cre mice. | | |  | a−f, We hybridized 3−5 coronal brain sections from each wildtype (a,b), f/fc-fos (c,d), and f/fc-fos−cre mouse (e,f) with a c-fos−specific probe. Panesl a, c and e show brain sections from untreated mice. Panels b, d and f show brain sections from mice treated with 20 mg kg-1 of kainic acid. g, Quantification of c-fos expression in the hippocampus and dentate of f/fc-fos−cre and two groups of control mice using in situ hybridization. Data represent mean  s.e.m. NT, no treatment; DG, dentate gyrus. h−m, We stained 3−5 coronal brain sections from each wildtype (h,i), f/fc-fos (j,k), and f/fc-fos−cre mouse (l,m) with an anti−c-Fos antibody. Panels h, j and l show brain sections from untreated mice. Panels i, k and m show brain sections from mice treated with 20 mg kg-1 of kainic acid. For these experiments, 2 untreated mice and 3−6 mice treated with kainic acid from each genotype were used. Mice treated with 30 mg kg-1 of kainic acid gave results parallel to those obtained for mice treated with 20 mg kg-1.
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To investigate the role of c-fos in seizures induced by kainic acid, we treated f/fc-fos-cre, wildtype, f/fc-fos and cre transgenic mice with kainic acid intraperitoneally (i.p.) and scored the degrees of seizure16. Kainic acid induced seizures of progressive severity in all groups of mice (Fig. 3a,b). Whereas there are no differences among the three control groups, f/fc-fos-cre mice show a higher degree of seizure at 20 mg kg-1 of kainic acid than the control groups (Fig. 3a; P<0.001). Although all four groups of mice showed apparently similar degrees of seizure when injected with 30 mg kg−1 of kainic acid (Fig. 3b), f/fc-fos-cre mice died more frequently, after extensive convulsive seizures, than the three control groups (Fig. 3c, P<0.05). Thus, kainic acid also induced more severe seizures in f/fc-fos-cre mice than in control mice at the 30 mg kg-1 dose. The increased seizure induction is specific to kainic acid, as f/fc-fos-cre mice do not differ from the three control groups of mice in seizures induced by a GABAergic inhibitor pentetrazole (PTZ) at doses of both 30 mg kg-1 (Fig. 3dx) and 50 mg kg-1 (Fig. 3e; P > 0.05). These results indicate that hippocampal mutation of c-fos leads to an increase in the severity of kainic acid−induced seizures in f/fc-fos-cre mice.
| | Figure 3. Kainic acid induces exceptionally severe seizures in the f/fc-fos-cre mouse. | | |  | a−c, Wildtype (+/+), cre transgenic (cre), f/fc-fos (f/f) and f/fc-fos−cre (-/-) mice were injected with kainic acid at 20 mg kg-1 (a, n=4−6 mice each) or 30 mg kg-1 (b, n=15−24 mice each). The percentage of mice that died after kainic acid administration at 30 mg kg-1 (c) is shown. d,e, Wildtype (+/+), cre transgenic (cre), f/fc-fos (f/f) and f/fc-fos−cre (-/-) mice were injected with PTZ at 30 mg kg-1 (d, n=4−5 mice each) or 50 mg kg-1 (e, n=4−7 mice each). Seizures were recorded and plotted. Data in a,b,d,e represent mean s.e.m.
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To test whether the increased severity of kainic acid−induced seizures seen in f/fc-fos-cre mice reflects increased neuronal excitability, we compared the electroencephalogram (EEG) patterns in cortex of wildtype and f/fc-fos-cre mice17. There was no significant difference in baseline EEGs between f/fc-fos-cre and wildtype mice in the amplitudes of spike-wave discharges in the absence of kainic acid (Fig. 4a). When we injected kainic acid i.p. at the 10 mg kg-1 dose, which is a sub-threshold for seizure induction, both f/fc-fos-cre and wildtype mice showed amplitudes of spike-wave discharges at higher than baseline levels (Fig. 4a,b). However, both the amplitudes of kainic acid−induced spike-wave discharges (Fig. 4b) and the frequency of spike-wave discharges whose amplitudes are higher than baseline levels (Fig. 4c, P<0.05) are significantly higher in f/fc-fos-cre mice than in wildtype mice. Thus, the c-fos mutation leads to increased neuronal excitability induced by kainic acid in f/fc-fos-cre mice.
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Rodent CA3 pyramidal neurons are more susceptible to kainic acid−induced death than other neurons in the hippocampus14,
18. To test whether c-fos may be neuroprotective against kainic acid−induced excitotoxicity, we assessed the degree of neuronal damage in the hippocampus in the four groups of mice that survived the 30 mg kg-1 of kainic acid treatment. Nissl staining of various brain sections indicates that f/fc-fos-cre mice have a greater amount of neuronal damage induced by kainic acid in the CA3 region (Fig. 5b,d) than wildtype (Fig. 5a,c), f/fc-fos and cre transgenic mice (data not shown). Immunostaining for the glial fibrillary acidic protein (GFAP) indicates that there is more gliosis in the CA3 region in f/fc-fos-cre mice (Fig. 5f) than in wildtype (Fig. 5ex), f/fc-fos and cre transgenic mice (data not shown). The excitotoxic neuronal cell death in the mutant mice is accompanied by more TUNEL staining in the CA3 region (Fig. 5h) than in wildtype mice (Fig. 5g). Quantification of lesion volumes in the CA3 region in all groups of mice shows a markedly greater amount of CA3 cell death induced by kainic acid in f/fc-fos−cre mice than in the three control groups (Fig. 5i; P<0.05). Thus, f/fc-fos-cre mice have more cell death in the CA3 region than control mice after 30 mg kg-1 of kainic acid exposure.
| | Figure 5. The f/fc-fos−cre mouse has a high rate of kainic acid−induced CA3 cell death. | | |  | Five days after seizure induction by 30 mg kg-1 of kainic acid, mice were perfused and their brains sectioned. a−d, We carried out Nissl staining (a and c, n=7 wildtype mice; b and d, n=5 f/fc-fos−cre mice). e−h, We also carried out immunostaining for GFAP (e,f) and TUNEL staining (g,h), using the above brain sections for both wildtype (e,g) and f/fc-fos−cre (f,h) mice. The scale bars indicate 1 mm for a, b, e, f, and 65  m for c, d, g, h. Arrows indicate lesioned brain regions. i, We carried out quantification of lesion volumes in the CA3 region of the hippocampus for all groups of mice at 30 mg kg-1 of kainic acid (n=5−7 mice each). Data represent mean s.e.m.; +/+, cre, f/f, and -/- represent wildtype, cre transgenic, f/fc-fos and f/fc-fos−cre mice, respectively. The asterisk indicates P<0.05. There is no major difference in neuronal damage among the four groups of mice in amygdala and pyriform cortex after exposure to kainic acid.
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It is thought that c-Fos functions through AP-1 transcription complexes to influence target gene expression. Supershift experiments19 indicate that there are changes in both level and composition in AP-1 complexes in the hippocampus and dentate, owing to a lack of c-Fos in f/fc-fos-cre mice, compared with control mice, before and after exposure to kainic acid (Web Fig. 3a−c). Moreover, western blotting indicates that in the absence of c-fos induction, absolute FosB levels are reduced; by contrast, Fra-1 and Fra-2 levels are higher in the hippocampus and dentate in f/fc-fos-cre mice, compared with wildtype mice, four hours after treatment with kainic acid (Fig. 6a). Together, our results suggest that c-fos regulates the overall composition of AP-1 transcription complexes both by direct participation and by regulation of other IEG expression.
| | Figure 6. c-fos regulates fosB, GluR6 and BDNF expression in vivo and in vitro. | | |  | Nuclear extracts were isolated from hippocampi, dentate and other brain regions of individual wildtype (+/+) and f/fc-fos−cre (-/-) mouse (n=4 mice for each time point) either before or after 30 mg kg-1 of kainic acid injections. a−c, Western blots for the indicated IEG products (a) and BDNF (c) before (0 h) and after 4 h or 5 d of treatment with kainic acid, and for GluR6 (b) before exposure to kainic acid. Equal amounts of protein were loaded in each lane. The status of only the full-length FosB is included, as our pan-Fos antibody and FosB antibody do not consistently detect  FosB upon administration of kainic acid. Expression of the R1 subunit of NMDA, GluR2, GluR3 and GluR7 receptors does not differ between mutant and control brains. Each experiment was repeated four times, and identical results were obtained. Hip, hippocampus; Ctx, cortex; CPu, caudoputamen; Cb, cerebellum. Increasing amounts of c-fos (1 and 2) were transfected into the indicated cells in duplicate, with mock-transfected cells (M) as controls. d,e, (see Methods) Forty-eight hours after transfection, cell extracts were isolated, and equal amounts of proteins were used for GluR6 (d), BDNF and FosB (e) as well as c-Fos (d,e) western blotting. Parallel results were obtained both within each transfection and among different transfections.
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The altered dynamic regulation of AP-1 complexes may lead to changes in target gene expression. To test this possibility, we selected two classes of candidate genes and investigated whether c-fos regulates their expression both in vivo and in vitro. The ionotropic GluRs mediate the fast excitatory neuronal transmission20. Several GluR genes have AP-1 binding sites in their promoter regions. We found a 1.8-fold increase in basal GluR6 expression in the hippocampus and dentate in naive f/fc-fos-cre mice compared with wildtype mice (Fig. 6b; P<0.01), whereas GluR6 is equally expressed in other brain regions, including cortex, striatum and cerebellum, in f/fc-fos-cre and wildtype mice (Fig. 6b; P>0.15). Basal expression of the other tested GluRs are similar in naive f/fc-fos-cre and wildtype mice (data not shown). Thus, basal levels of c-Fos contribute to regulation of GluR6 expression in the hippocampus.
The neutrophin BDNF and its high- and low-affinity receptors, TrkB and p75NTR, are implicated in neuronal protection against kainic acid−induced seizures21,
22,
23,
24,
25. We examined whether c-fos is involved in regulating their expression in the hippocampus and dentate. Four hours after exposure to kainic acid, BDNF levels in f/fc-fos-cre mice remain similar to basal levels, whereas they are twofold higher than basal levels in wildtype mice (Fig. 6c; P<0.01). Basal and kainic acid−induced BDNF expression at the 48-hour time point are not overtly affected by the c-fos mutation. Both basal and kainic acid−induced levels of TrkB and p75NTR are similar in f/fc-fos-cre and wildtype mice at all time points measured (data not shown). These results indicate that there is a delayed BDNF induction by kainic acid in the hippocampus in f/fc-fos-cre mice, compared with wildtype mice.
To further test whether c-fos regulates GluR6, BDNF and fosB expression, we transiently transfected several cell lines with c-fos and measured the expression of the three genes. Similar to the results observed in vivo, an increasing amount of c-Fos reduces GluR6 expression (Fig. 6d) while increasing BDNF or fosB expression in vitro (Fig. 6e). The parallel changes observed both in vivo and in vitro suggest that the increased basal GluR6 expression and the delayed BDNF induction by kainic acid in f/fc-fos-cre mice, compared with wildtype mice, are most likely due to a lack of direct c-Fos-mediated transcriptional regulation rather than to various indirect mechanisms or effects of the c-fos mutation.
Together, our results support a genetic model in which c-Fos participates in key cellular mechanisms underlying both neuronal excitability and protection by selectively regulating gene expression in the brain. In normal neurons, basal c-Fos or c-Fos induced by neuronal activity orchestrates the formation of AP-1 transcription complexes, either by direct participation or by regulation of other IEG expression. Basal AP-1 complexes regulate the expression of GluR6, which mediates neuronal excitability26. Induced AP-1 complexes regulate BDNF to help cell survival after excessive stimulation. The dual regulation of the two cellular mechanisms by c-Fos ensures appropriate neuronal excitability and protects neurons from potential excitotoxicity. Future studies may identify additional molecular targets and cellular pathways underlying excitability, survival and plasticity.
Methods
Generation of f/fc-fos-cre mice.
We designed a c-fos targeting construct to delete the coding sequence for the DNA binding domain and the leucine zipper domain that are important for heterodimerization with the Jun family proteins. We generated homologous recombinants and chimeric mice as described27. We bred male chimeric mice with C57BL/6 females and identified germline transmission and f/fc-fos mice by genomic Southern blotting. We then crossed f/fc-fos mice with the T50 mice carrying a cre transgene driven by a CaMKII promoter15. The genotypes of the offspring were identified by genomic Southern blotting with 5' and 3' probes for loxP-c-fos−loxP and with a cre gene probe. We used mutant and their various control littermates at 10−18 wk for all subsequent analyses.
Seizure scoring and statistical analysis.
We injected mice i.p. with kainic acid at 20 mg kg-1 or 30 mg kg-1 of body weight. We then scored kainic acid−induced seizures every 5 min for 2 h, according to Yang et al.16. This seizure scoring system does not distinguish between generalized tonic-clonic activity and death, with death clearly representing a higher degree of seizure. We injected PTZ similarly at 30 mg kg-1 or 50 mg kg-1 of body weight and scored seizures based on the highest degree of seizure within 15 min of the PTZ injection. For seizure data analysis, we constructed a 2  4 contingency table with the degree of response to kainic acid injections grouped as less than 3 and greater than or equal to 3, followed by Chi-square analysis. The comparison between the f/fc-fos-cre group and the other three control groups was carried out with Freeman-Tukey's multiple comparison, after the percentage data were transformed with an Arcsine function. The kainic acid−induced death rate comparison was carried out by Chi-square analysis. We analyzed the PTZ seizure results using an unpaired t-test between the f/fc-fos-cre and the three control groups of mice.
In situ hybridization and quantification.
We fixed and processed brain sections27. We then used mouse c-foscDNA to make a [35S]UTP-labeled antisense riboprobe. We used a sense probe as a control. After hybridization, the slides were dehydrated, dipped in NTB2 photographic emulsion (Kodak) and stored. We stained brain sections with cresyl violet and took pictures of each area of each section at 50 magnification, using NIH Image for quantification. We then counted the silver grains on each cell in defined areas of CA1, CA2, CA3, dentate gyrus and other brain regions with matching sections for all mice, as well as in cell-sized areas of the background. Any cell that contained six times or more the number of grains as the background was counted as a positive cell. We derived this number by comparing values from known positives and negatives and determining a fair value for what is positive.
Immunohistochemistry.
We used 40-m brain sections with antibodies for c-Fos (Oncogene Research Products), c-Jun (Santa Cruz Biotechnology), pSer73-c-Jun (New England Biolab) and GFAP (Dako). We incubated the sections with a biotinylated secondary antibody27 (Vector Laboratories) followed by ABC reagent (ABC kit, Vector Laboratories). We visualized the immunoreaction by treating the sections in 0.05% diaminobenzidine with hydrogen peroxide.
Electroencephalogram analysis.
We placed two blunt-tip tungsten electrodes on the dura above the sensory motor cortex and a reference electrode on the nasal bone17. We used a high-input impedance amplifier for recording and recorded the signals on a digital tape. We first recorded baseline EEGs in the absence of kainic acid. We next injected kainic acid i.p. at 5 mg kg-1 and recorded EEG for 90 min. We then injected kainic acid at 10 mg kg-1 and recorded EEG for another 90 min. Samples of 2.5-s EEG recordings at every 5-min interval for each mouse were compared between f/fc-fos-cre and wildtype mice for spike-wave discharges. We carried out Student's t-tests between groups to determine the significance in genotypes.
Evaluating neuronal damage.
We stained serial brain sections from the surviving mice with cresyl violet, for neuronal damage evaluation, as described16. We quantified neuronal loss by measuring the areas of severe neuronal damage on every second section, using the Metamorph Imaging system, and integrated sections to calculate volumes of damage of the four genotypes in dorsal hippocampus. An unpaired t-test was done on the lesion volumes between the f/fc-fos-cre and each of the three control groups of mice. We evaluated neuronal damage-induced gliosis by immunostaining for GFAP. We also carried out the TUNEL assay with the above brain sections using the In Situ Cell Death Detection Kit in conjunction with the peroxidase-conjugated anti-fluorescein antibody detection system (TUNEL POD) from Boehringer Mannheim.
Protein extract preparation and analysis of DNA-binding activities.
We prepared nuclear extracts from hippocampi and dentate19. We analyzed DNA-binding activities of the nuclear proteins using the electrophoretic mobility shift assay19. We mixed nuclear extracts with an end-labeled AP-1 oligonucleotide and electrophoresed the mixtures in a nondenaturing gel. Gels were dried and exposed. We scanned autoradiographs using a Molecular Dynamics scanner and analyzed the results by ImageQuant software. We carried out supershifts as described19. We used polyclonal antibodies (Santa Cruz Biotechnology) against c-Fos, FosB, Fra-1, Fra-2, c-Jun, JunB and JunD. We repeated each experiment four times and obtained identical results.
Cell transfection and protein extract preparation.
Both the mouse neuroblastoma Neuro2A and the human glioblastoma U251 cells express endogenous BDNF, and the human teratocarcinoma NT2 cells show endogenous GluR6 expression. We transfected 80% confluent cells with 1−4 g of pCMV-c-fos containing rat c-fos with a deletion of the 3' UTR, to stabilize the c-Fos products by lipofection (FuGENE 6, Roche). Forty-eight hours after transfection, we harvested, washed and homogenized the cells and used the extracts for western blotting. All transfections were done in duplicate and each transfection was repeated at least three times.
Western blotting and data analysis.
We isolated hippocampi and dentate from each mouse individually at different time points and homogenized the tissues. These extracts, and those from the transfection experiments, were quantified and separated by SDS−PAGE, transferred to nitrocellulose membranes, probed with antibodies (Santa Cruz Biotechnology) against c-Fos, FosB, Fra-1, Fra-2, c-Jun, JunB, JunD, BDNF, TrkB, p75NTR, NMDA R1, GluR2-3, GluR6-7 and actin, and secondary antibodies. We visualized the results by enhanced chemiluminenscence (Amersham). Western blotting for each sample was done at least twice. We quantified data by densitometer scanning followed by Student's t-tests.
Note: Supplementary figures are available on the Nature Genetics web site.
Received 6 December 2001; Accepted 23 January 2002; Published online: 4 March 2002.
REFERENCES
- Choi, D.W. Glutamate neurotoxicity and diseases of the nervous system. Neuron 1, 623−634 (1988). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Coyle, J.T. & Puttfarcken, P. Oxidative stress, glutamate, and neurodegenerative disorders. Science 262, 689−695 (1993). | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Lee, J.-M., Zipfel, G.J. & Choi, D.W. The changing landscape of ischaemic brain injury mechanisms. Nature 399, A7−A14 (1999). | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- McNamara, J.O. Emerging insights into the genesis of epilepsy. Nature 399, A15−A22 (1999). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Muller, R., Tremblay, J.M., Adamson, E.D. & Verma, I.M. Tissue and cell type-specific expression of two human c-onc genes. Nature 304, 454−456 (1983). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Greenberg, M.E. & Ziff, E.M. Stimulation of 3T3 cells induces transcription of the c-fos proto-oncogene. Nature 311, 433−438 (1984). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Chiu, R. et al. The c-Fos protein interacts with c-Jun/AP-1 to stimulate transcription of AP-1 responsive genes. Cell 54, 541−542 (1988). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Halazonetis, T.D., Georgopoulos, K., Greenberg, M.E. & Leder, P. c-Jun dimerizes with itself and with c-Fos, forming complexes of different DNA binding affinities. Cell 55, 917−924 (1988). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Kouzarides, T. & Ziff, E. The role of the leucine zipper in the Fos-Jun interaction. Nature 336, 646−651 (1988). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Smeyne, R.J. et al. Continuous c-fos expression precedes programmed cell death in vivo. Nature 363, 166−169 (1993). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Popovici, T. et al. Effects of kainic acid-induced seizures and ischemia on c-fos-like proteins in rat brain. Brain Res. 536, 183−194 (1990). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Smeyne, R.J. et al. Fos-lacZ transgenic mice: mapping sites of gene induction in the central nervous system. Neuron 8, 13−23 (1992). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Ferkany, J.W., Zaczek, R. & Coyle, J.T. The mechanism of kainic acid neurotoxicity. Nature 308, 561−562 (1984). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Ben-Ari, Y. Limbic seizure and brain damage produced by kainic acid: mechanisms and relevance to human temporal epilepsy. Neuroscience 14, 375−403 (1985). | Article | PubMed | ChemPort | Add to Connotea (beta) |
- Tsien, J.Z. et al. Subregion- and cell type-restricted gene knockout in mouse brain. Cell 87, 1317−1326 (1996). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Yang, D.D. et al. Absence of excitotoxicity-induced apoptosis in the hippocampus of mice lacking the Jnk3 gene. Nature 389, 865−870 (1997). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Medvedev, A., Mackenzie, L., Hiscock, J.J. & Willoughby, J.O. Kainic acid induces distinct types of epileptiform discharge with differential involvement of hippocampus and neocortex. Brain Res. Bull. 52, 89−98 (2000). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Nadler, J.V., Perry, B.W. & Cotman, C.W. Intraventricular kainic acid preferentially destroys hippocampal pyramidal cells. Nature 271, 676−677 (1978). | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Mandelzys, A., Gruda, M.A., Bravo, R. & Morgan, J.I. Absence of a persistently elevated 37 kDa fos-related antigen and AP-1-like DNA-binding activity in the brains of kainic acid-treated fosB null mice. J. Neurosci. 17, 5407−5415 (1997). | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Hollmann, M. & Heinemann, S. Cloned glutamate receptors. Ann. Rev. Neurosci. 17, 31−108 (1994). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Koh, J.-Y., Gwag, B.J., Lobner, D. & Choi, D.W. Potentiated necrosis of cultured cortical neurons by neurotrophins. Science 268, 573−575 (1995). | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Tandon, P., Yang, Y., Das, K., Holmes, G.L. & Stafstrom, C.E. Neuroprotective effects of brain-derived neurotrophic factor in seizures during development. Neuroscience 91, 293−303 (1999). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Gall, C.M. Seizure-induced changes in neurotrophin expression: implications for epilepsy. Exp. Neurol. 124, 150−166 (1993). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Merlio, J.-P. et al. Increased production of the TrkB protein tyrosine kinase receptor after brain insults. Neuron 10, 151−164 (1993). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Roux, P.P., Colicos, M.A., Barker, P.A. & Kennedy, T.E. p75 neurotrophin receptor expression is induced in apoptotic neurons after seizure. J. Neurosci. 19, 6887−6896 (1999). | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Mulle, C. et al. Altered synaptic physiology and reduced susceptibility to kainate-induced seizures in GluR6-deficient mice. Nature 392, 601−605 (1998). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
- Xu, M. et al. Dopamine D1 receptor mutant mice are deficient in striatal expression of dynorphin and in dopamine-mediated behavioral responses. Cell 79, 729−742 (1994). | Article | PubMed | ISI | ChemPort | Add to Connotea (beta) |
Acknowledgments
We are grateful to J. Duffy and M. Yin for mouse blastocyst injections. We thank L. Chen, R. Hennigan, H. Jansen, A. Kuan, H. Lee, D. Lou, M. Privitera, L. Sherman and R. Walsh for various advice, help and discussions. J.Z. and M.X. are supported by grants from the National Institutes of Health, the National Alliance for Research on Schizophrenia and Depression and the Epilepsy Foundation of America. J.S.M. is partially supported by an NIH predoctoral training grant.
Competing interests statement:
The authors declare that they have no competing financial interests. |
