Three NF-kappa B sites in the I kappa B-alpha promoter are required for induction of gene expression by TNF alpha.

NF-kappa B was first identified as a postive regulator which bound to a 10 bp sequence in the first intron of the Ig kappa light chain gene. Further characterization of this transcription factor has revealed that NF-kappa B is kept from binding to its consensus sequence by its inhibitor, IkB-alpha, which retains NF-kappa B in the cytoplasm. Upon receiving various extra- and intracellular signals, I kappa B-alpha is rapidly degraded and NF-kappa B is induced to translocate into the nucleus. This process precedes the rapid induction of I kappa B-alpha mRNA and protein. To understand how I kappa B-alpha is replenished, we have cloned and sequenced the 5' flanking region of the I kappa B-alpha gene and have identified the transcription start site and three NF-kappa B sites in this region. Further characterization of these NF-kappa B sites show that they have different affinities for three specific protein complexes which we identify here to consist of various members of the Rel family. In transient assays, cotransfection with a p65 expression vector is able to activate an I kappa B-alpha promoter-CAT reporter construct and all three NF-kappa B sites are required for full activation of the I kappa B-alpha gene following stimulation with TNF-alpha. Our data confirm a transcriptional autoregulatory loop involved in maintaining appropriate NF-kappa B and I kappa B-alpha levels in the cell

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Tissue-Specific Tumour Suppressor and Oncogenic Activities of the Polycomb-like Protein MTF2

The Polycomb repressive complex 2 (PRC2) is a conserved chromatin-remodelling complex that catalyses the trimethylation of histone H3 lysine 27 (H3K27me3), a mark associated with gene silencing. PRC2 regulates chromatin structure and gene expression during organismal and tissue development and tissue homeostasis in the adult. PRC2 core subunits are associated with various accessory proteins that modulate its function and recruitment to target genes. The multimeric composition of accessory proteins results in two distinct variant complexes of PRC2, PRC2.1 and PRC2.2. Metal response element-binding transcription factor 2 (MTF2) is one of the Polycomb-like proteins (PCLs) that forms the PRC2.1 complex. MTF2 is highly conserved, and as an accessory subunit of PRC2, it has important roles in embryonic stem cell self-renewal and differentiation, development, and cancer progression. Here, we review the impact of MTF2 in PRC2 complex assembly, catalytic activity, and spatiotemporal function. The emerging paradoxical evidence suggesting that MTF2 has divergent roles as either a tumour suppressor or an oncogene in different tissues merits further investigations. Altogether, our review illuminates the context-dependent roles of MTF2 in Polycomb group (PcG) protein-mediated epigenetic regulation. Its impact on disease paves the way for a deeper understanding of epigenetic regulation and novel therapeutic strategies