As part of our effort to sequence the 100-megabase (Mb) genome of the nematode Caenorhabditis elegans, we have completed the nucleotide sequence of a contiguous 2,181,032 base pairs in the central gene cluster of chromosome III. Analysis of the finished sequence has indicated an average density of about one gene per five kilobases; comparison with the public sequence databases reveals similarities to previously known genes for about one gene in three. In addition, the genomic sequence contains several intriguing features, including putative gene duplications and a variety of other repeats with potential evolutionary implications.

Temporal lobe epilepsy is a common form of drug-resistant epilepsy that sometimes responds to dietary manipulation such as the 'ketogenic diet'. Here we have investigated the effects of the glycolytic inhibitor 2-deoxy-D-glucose (2DG) in the rat kindling model of temporal lobe epilepsy. We show that 2DG potently reduces the progression of kindling and blocks seizure-induced increases in the expression of brain-derived neurotrophic factor and its receptor, TrkB. This reduced expression is mediated by the transcription factor NRSF, which recruits the NADH-binding co-repressor CtBP to generate a repressive chromatin environment around the BDNF promoter. Our results show that 2DG has anticonvulsant and antiepileptic properties, suggesting that anti-glycolytic compounds may represent a new class of drugs for treating epilepsy. The metabolic regulation of neuronal genes by CtBP will open avenues of therapy for neurological disorders and cancer.

Negative regulation of transcription is an important strategy in establishing and maintaining cell-specific gene expression patterns. Many neuronal genes are subject to active transcriptional repression outside the nervous system to establish neuronal specificity. NRSF/REST has been demonstrated to regulate at least 30 genes and contribute to their neuronal targeting by repressing transcription outside the nervous system. Further, human genome database searches reveal that over 800 genes contain an NRSE. Here we report that NRSF recruits the histone methylase G9a to silence NRSF target genes in nonneuronal cells. We show that G9a generates a highly localized domain of dimethylated histone H3-K9 around NRSEs, but H3-K27 remains unmethylated. The NRSEs are also associated with HP1. Finally, we demonstrate that dominant-negative G9a abrogates silencing of chromosomal neuronal genes. These findings implicate a role for histone methylation in targeting neuronal gene expression to the nervous system.

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