Diversification of HP1-like Chromo Domain Proteins in Tetrahymena thermophila.

Proteins that possess a chromo domain are well-known for their roles in heterochromatin assembly and maintenance. The Heterochromatin Protein 1 (HP1) family, with a chromo domain and carboxy-terminal chromo shadow domain, targets heterochromatin through interaction with histone H3 methylated on lysine 9 (H3K9me2/3). The structural and functional diversity of these proteins observed in both fission yeast and metazoans correlate with chromatin specialization.

LIA4 encodes a chromoshadow domain protein required for genomewide DNA rearrangements in Tetrahymena thermophila.

Extensive DNA elimination occurs as part of macronuclear differentiation during Tetrahymena sexual reproduction. The identification of sequences to excise is guided by a specialized RNA interference (RNAi) machinery that targets the methylation of histone H3 lysine 9 (K9) and K27 on chromatin associated with these internal eliminated sequences (IESs). This modified chromatin is reorganized into heterochromatic subnuclear foci, which is a hallmark of their subsequent elimination.

Genome biology: the sleek and oh-so chic Oxytricha nanochromosomes.

The somatic nucleus of Oxytricha trifallax contains over 15,000 different chromosomes, most containing a single gene. Analysis of this 50 Mb genome uncovers novel regulatory strategies and adaptive potential when gene copy number and allelic frequency are no longer constrained by genetic linkage.

Embryonic stem cells as a platform for analyzing neural gene transcription.

There is a need for improved methods to analyze transcriptional control of mammalian stem cell genes. We propose that embryonic stem cells (ESCs) will have broad utility as a model system, because they can be manipulated genetically and then differentiated into many cell types in vitro, avoiding the need to make mice. Results are presented demonstrating the utility of ESCs for analyzing cis-acting sequences using Olig2 as a model gene.

Somatostatin and gamma-aminobutyric acid inhibit interleukin-1 beta-stimulated release of interleukin-6 from rat C6 glioma cells.

Objective: We investigated the ability of inhibitory neurotransmitters to alter the interleukin-1 beta (IL-1 beta)-stimulated release of interleukin-6 (IL-6) from cultured glial tumor cells.

Methods: C6 rat glioblastoma cells were exposed to either IL-1 beta or its putative second messenger lysophosphatidylcholine (LPC) in the absence or presence of the inhibitory neurotransmitters somatostatin (SRIF) or gamma-aminobutyric acid (GABA). Alternatively, C6 cells were pretreated with selective inhibitors of JNK or p38 and then exposed to either IL-1 beta or LPC to determine the relative involvement of these terminal stress kinases in the stimulation of IL-6 release.