Immunocytochemistry was used to study the expressions of glutamate receptor subunit proteins for NMDAR2A/B, NMDAR1 splice variants, and AMPA Glu-R2/3 in human brain resected for intractable epilepsy associated with cortical dysplasia. NMDAR2A/B intensely labeled dysplastic neurons showing staining in both the cell bodies and dendritic profiles. However, nondysplastic neurons were not immunoreactive to NMDAR2A/B. The antibody selective to NMDAR1 splice variants of NR1-1a. -1b, -2a, and -2b labeled dysplastic neurons, but few nondysplastic neurons. In contrast, the antibody to splice variants of NR1-1a, -1b, 2a, -2b, -3a, -3b, -4a, and -4b labeled both dysplastic and nondysplastic neurons. The different labeling patterns by these two antibodies indicate that variants of NMDAR1-3a, -3b, -4a, and -4b are present in nondysplastic neurons. Both dysplastic neurons and nondysplastic neurons were immunoreactive to AMPA GluR2/3, but denser immunoreactivity was observed in dysplastic neurons. We also found that the locations of dysplastic neurons labeled by NMDAR2A/B were related to focal epileptic EEG seizure onsets or spiking and to focal behavioral seizure types. Our results suggest that there is hyperexcitability of dysplastic cortical regions, at least in part, from the presence of NMDAR2 subunits and selectively expressed NMDAR1 splice variants in dysplastic neurons.

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Four distinct promoters (1A, 1B, 1C, and 1D) of fibroblast growth factor 1 (FGF1), spaced up to 70 kilobase pairs apart, direct the expression of alternatively spliced transcript variants (FGF1.A, -1.B, -1.C, and -1.D) that encode FGF1. These FGF1 transcripts can be detected in cultured cells as well as in normal and diseased tissues. These transcripts are differentially regulated in a cell-specific manner. To further delineate the biological function of multiple promoter usage by a single gene, we investigated the transcriptional regulation of these promoters by defined signaling pathways associated with cell proliferation and cell survival. Here we show a specific association of two of the FGF1 promoters, 1C and 1D, with signaling cascades of the Ras superfamily of GTPases. A serum-response element, comprised of the Ets and CArG motifs, present in promoter 1D was shown to be the target of distinct signaling cascades; the Ets motif target of Ras, Rac1, and Cdc42 regulation; and the CArG motif target of de novo protein synthesis-independent cascade. Ras and Rac1 also activated the FGF2 promoter. Further, the transcription factor Ets2 synergistically activated FGF1 gene, but not FGF2, in a Rasand Rac1-dependent signaling pathway. In support of these conclusions high levels of intracellular FGF1 were detected in cells undergoing cytokinesis. Altogether, our results suggest that FGF1 may play a fundamental role in cell division, spreading, and migration, in addition to cell proliferation. Fibroblast growth factor 1 (FGF1)1 is a potent angiogenic and cell survival factor (1). Its 155-amino acid single chain polypeptide is encoded by three protein-coding exons. However, the FGF1 gene organization, spanning more than 100 kbp, as well as expression pattern of FGF1 transcripts, is indeed complex because of the existence of at least four 5Ј-untranslated exons (2). Four different FGF1 transcripts (FGF1.A, -1.B, -1.C, and -1.D), varying only in the 5Ј-untranslated region, originate from four distinct promoters (1A, 1B, 1C, and 1D) (2-4). These promoters are differentially regulated in a cell-and tissuespecific manner (4 -7). FGF1.A transcript was detected exclusively in the kidney (2, 3). High FGF1 promoter 1B activity was detected in a glioblastoma cell line U1240MG with promoter construct extending up to nucleotide Ϫ540 from the transcription start site. This activity was attributed to a 23-bp ciselement (Ϫ489 to Ϫ467). A 37-kDa protein, designated p37 brn , was found to associate within this sequence and postulated to positively regulate expression of FGF1.B transcript in the brain (5-6). In contrast, a basic helix-loop-helix protein, E2-2, negatively regulates the 1B promoter (7). Also, FGF1 promoter 1C construct extending up to Ϫ1614 from the transcription start site displayed activity in PC-3 prostate carcinoma cells and serum inducibility in MDA-MB-231 breast carcinoma cells. The promoter contained cis-elements that included activator protein 1, activator protein 2, and Sp1. These elements showed specific associatio...