Epigenetic regulation at MLL1 target genes

The mixed-lineage leukaemia 1 protein is a histone methyl-transferase that deposits the gene activating H3K4 trimethyl mark, and is often mutated in leukaemia. MLL1 is normally associated with a cohort of cofactors, but the mechanisms regulating the histone methyl-transferase activity remain unclear. Here I examine the role of Msk1, a downstream kinase of the MAP-kinase pathway, in regulating MLL1 activity. Msk1 is known to deposit the H3S10 phosphorylation mark, which was found to stimulate MLL1’s methylation activity $in$ $vitro$. Here I demonstrate that MLL1 and Msk1 can be immunoprecipitated and their patterns of genomic binding show an overlap at ~30 of sites, suggesting a direct functional interaction. In transient MLL1 and Msk1 knock-down cells, known MLL1 target genes were down-regulated and at a global level, 30% of all responding genes were regulated in the same manner. Furthermore, key histone modifications at MLL1 target genes change in Msk1 knock-down cells, suggesting that histone cross-talk within the MLL1 complex acts as a means of gene regulation. Finally, cell cycle studies suggest MLL1-Msk1 cross-talk may stimulate MLL1-driven gene expression after mitosis. These findings suggest that MLL1 is regulated by Msk1 and therefore by extracellular signals via the MAP-kinase pathway

Cells adapt to the epigenomic disruption caused by histone deacetylase inhibitors through a coordinated, chromatin-mediated transcriptional response

BACKGROUND: The genome-wide hyperacetylation of chromatin caused by histone deacetylase inhibitors (HDACi) is surprisingly well tolerated by most eukaryotic cells. The homeostatic mechanisms that underlie this tolerance are unknown. Here we identify the transcriptional and epigenomic changes that constitute the earliest response of human lymphoblastoid cells to two HDACi, valproic acid and suberoylanilide hydroxamic acid (Vorinostat), both in widespread clinical use. RESULTS: Dynamic changes in transcript levels over the first 2 h of exposure to HDACi were assayed on High Density microarrays. There was a consistent response to the two different inhibitors at several concentrations. Strikingly, components of all known lysine acetyltransferase (KAT) complexes were down-regulated, as were genes required for growth and maintenance of the lymphoid phenotype. Up-regulated gene clusters were enriched in regulators of transcription, development and phenotypic change. In untreated cells, HDACi-responsive genes, whether up- or down-regulated, were packaged in highly acetylated chromatin. This was essentially unaffected by HDACi. In contrast, HDACi induced a strong increase in H3K27me3 at transcription start sites, irrespective of their transcriptional response. Inhibition of the H3K27 methylating enzymes, EZH1/2, altered the transcriptional response to HDACi, confirming the functional significance of H3K27 methylation for specific genes. CONCLUSIONS: We propose that the observed transcriptional changes constitute an inbuilt adaptive response to HDACi that promotes cell survival by minimising protein hyperacetylation, slowing growth and re-balancing patterns of gene expression. The transcriptional response to HDACi is mediated by a precisely timed increase in H3K27me3 at transcription start sites. In contrast, histone acetylation, at least at the three lysine residues tested, seems to play no direct role. Instead, it may provide a stable chromatin environment that allows transcriptional change to be induced by other factors, possibly acetylated non-histone proteins. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13072-015-0021-9) contains supplementary material, which is available to authorized users

Incidence of Interval Colorectal Cancer After Negative Results From First-Round Fecal Immunochemical Screening Tests, by Cutoff Value and Participant Sex and Age

Background & Aims: We evaluated the incidence of interval cancers between the first and second rounds of colorectal cancer (CRC) screening with the FOB-Gold fecal immunochemical test (FIT), and the effects of different cutoff values and patient sex and age. Methods: We collected data from participants in a population-based

Part 1: Role of the histone kinase MSK1 on MLL gene regulation & Part 2: the molecular basis of inhibitory siganlling during neuronal regeneration.

Part 1: The mixed-lineage leukaemia (MLL) protein is a histone methyl-transferase, that deposits the trimethylation mark on Lysine 4 of Histone 3 (H3K4me3) and that is often mutated in certain forms of leukaemia. MLL is normally associated with a cohort of other proteins and cofactors, but the mechanisms regulating MLL activity remain unclear. The H3K4me3 mark, as deposited by MLL‘s SET domain, which is found in many proteins and mediate lysinedirected histone methylation, is asociated with actively transcribed genes. Here we examine the role of Msk1, a downstream kinase of the MAP-kinase pathway, in regulating MLL1 activity. Msk1 is known to deposit phosphorylation marks on H3 and these were found on MLL1 target genes and the same target site like MLL1. It could be demonstrated that in Msk1 knock-down cells the MLL1 target genes are down-regulated. Furthermore during the cell cycle MLL1 and Msk1 show the same varying distribution. These findings suggest that MLL1 is regulated by extracellular signals via the MAP-kinase pathway and Msk1. Part 2: Limited neuronal regeneration following CNS injury is due to interactions between the myelin derived inhibitors and the Nogo-receptor (NgR) ternary complex, consisting of NgR, p75 and Lingo1. The inhibitory role of Lingo-1 presents a novel target for nerve repair and remyelination therapies. Lingo1 is one member of a large group of CNS enriched membrane proteins, with a LRR and an Ig domain in their ectodomain. Recently, other members of the LRR-Ig protein family, namely Amigo-proteins, have been reported in the context of neuronal development, survival and regeneration. This study has combined biochemical, binding and structural approaches to further characterise the function of Amigo proteins, with a particular emphasis on whether Amigo proteins can substitute for Lingo1 in forming a ternary NgR complex. The ectodomains of Amigo1 and Amigo3 were expressed and successfully purified by Ni-NTA affinity and gel filtration chromatography. Based on BIAcore binding analyses, whereas Amigo 1 and Amigo 3 demonstrated no binding with p75, weak interactions were found with NgR. In addition, initial cross-linking experiments with BS$^3$ indicated, that Amigo1, but not Amigo 3, can self-associate forming dimers in solution. Finally, crystallisation trials for Amigo1 ectodomain identified a condition that yielded suitable sized crystals for preliminary X-ray diffraction experiments

Additional file 6: of Cells adapt to the epigenomic disruption caused by histone deacetylase inhibitors through a coordinated, chromatin-mediated transcriptional response

A table showing “pattern specification process genes” that are up-regulated by HDACi treatment

Additional file 4: of Cells adapt to the epigenomic disruption caused by histone deacetylase inhibitors through a coordinated, chromatin-mediated transcriptional response

All genes responding significantly to 0.2 mM VPA

Additional file 1: of Cells adapt to the epigenomic disruption caused by histone deacetylase inhibitors through a coordinated, chromatin-mediated transcriptional response

The global changes in histone modification and cell cycle profile in cells treated with HDACi

Ultrafast IR Spectroscopy on Aqueous Reverse-Micellar Nano-Droplets

The ultrafast dynamics of water nano-droplets (1-10 nm size) of the L2-phase of the ternary mixture H2O-AOT-CCl4 have been studied using frequency-resolved mid-infrared pump-probe spectroscopy in the spectral region of the OH-stretching vibration.

Low frequency maintenance therapy with imiglucerase in adult type I Gaucher disease: a prospective randomized controlled trial

BACKGROUND AND OBJECTIVES: Gaucher disease type I can be successfully treated with enzyme replacement therapy (ERT). In order to reduce the burden of the intravenously administered enzyme, a low frequency of administration was prospectively studied in patients with stable and minor disease following ERT. DESIGN AND METHODS: Eleven patients were randomly assigned either to continue their original regimen of a dose of ERT once every week or fortnight (five patients) or to lower the frequency of administration to once every 4 weeks, at the same cumulative dose (six patients). The primary end-point was change in liver ratio (mL/kg body weight). Secondary end-points were spleen volume, hemoglobin level, platelet count, lumbar bone marrow fat content measured with quantitative chemical shift imaging (QCSI), white cell count, and plasma levels of ferritin, chitotriosidase, liver enzymes and angiotensin-converting enzyme (ACE). RESULTS: There were no significant mean differences between the two treatment arms in liver ratio or any of the other end-points. However, there were two treatment failures in the low frequency of administration group. These patients showed progression of disease as evidenced by a reduction of QCSI in one patient and an increase in liver ratio as well as a slow decrease in QCSI in the other. Both patients already had relatively low baseline QCSI values. One patient switched back to the original regimen at 6 months because of subjective complaints. INTERPRETATION AND CONCLUSIONS: Low frequency ERT in adult Gaucher type I patients maintains stable disease in most, but not all patients with stable and minimal disease. Close monitoring of all disease parameters remains mandator