Synthesis of a novel series of thiazole-based histone acetyltransferase inhibitors.

Acetylation, which targets a broad range of histone and non-histone proteins, is a reversible mechanism and plays a critical role in eukaryotic genes activation/deactivation. Acetyltransferases are very well conserved through evolution. This allows the use of a simple model organism, such as budding yeast, for the study of their related processes and to discover specific inhibitors. Following a simple yeast-based chemogenetic approach, we have identified a novel HAT (histone acetyltransferase) inhibitor active both in vitro and in vivo. This new synthetic compound, 1-(4-(4-chlorophenyl)thiazol-2-yl)-2-(propan-2-ylidene)hydrazine, named BF1, showed substrate selectivity for histone H3 acetylation and inhibitory activity in vitro on recombinant HAT Gcn5 and p300. Finally, we tested BF1 on human cells, HeLa as control and two aggressive cancer cell lines: a neuroblastoma from neuronal tissue and glioblastoma from brain tumour. Both global acetylation of histone H3 and specific acetylation at lysine 18 (H3AcK18) were lowered by BF1 treatment. Collectively, our results show the efficacy of this novel HAT inhibitor and propose the utilization of BF1 as a new, promising tool for future pharmacological studies.

Síntesis y evaluación de nuevos inhibidores de las HDAC / Synthesis and evaluation of new HDAC inhibitors

La acetilación de residuos de lisina en las histonas está mediada por las enzimas denominadas histona acetiltransferasas (HAT). Los grupos acetilo son eliminados de las e-N-acetil-lisinas por la actividadde las histonas desacetilasas (HDAC). El balance entre las actividades opuestas de las HAT y las HDAC regula el estado de acetilación de las histonas. Este tipo de modificaciones regulan en la célula procesos fundamentales clave en respuesta a señales extracelulares. En general, altos niveles de acetilación (hiperacetilación) se asocian a un incremento de la actividad transcripcional, mientras que bajos niveles de acetilación (hipoacetilación) se asocian a la represión de la expresión genética. Actualmente se conocen diversos tipos de inhibidores de las HDAC que pueden reactivar la expresión genética e inhibir el crecimiento de las células tumorales, por lo que se investiga su uso en el tratamiento frente al cáncer. Sería deseable identificar nuevos inhibidores de las enzimas HDAC para su utilización en el tratamiento o profilaxis de enfermedades en las que la inhibición de dichas enzimas HDAC está implicada. Se han obtenido 10 nuevos inhibidores de las HDAC y se ha evaluado su actividad frente a HDAC aislada. Se discute la importancia de las modificaciones realizadas en el espaciador(AU)

Lysine residues acetylation on histones is mediated by histone acetyltransferase (HAT). The acetyl groups are removed from e-N-acetyl-lysine by the histone deacetylase (HDAC) activity. The balance between the HATs and HDACs activities regulates the histone acetylation status. Such changes regulate key processes in the cell in response to extracellular signals. Mostly, high levels of acetylation(hyperacetylation) are associated with increased transcriptional activity. Low levels of acetylation (hypoacetylation) are associated with repression of gene expression. Currently, different types of HDAC inhibitors are known to reactivate gene expression and inhibit tumor cell growth. We aim at identifying novel HDAC inhibitors for the treatment or prophylaxis of cancer diseases. Ten new HDAC inhibitors have been obtained and their potency as HDAC inhibitors has been evaluated. A structure-activity relationship discussion has been focused on the structural changes made in the spacer(AU)

The structural basis of protein acetylation by the p300/CBP transcriptional coactivator.

The transcriptional coactivator p300/CBP (CREBBP) is a histone acetyltransferase (HAT) that regulates gene expression by acetylating histones and other transcription factors. Dysregulation of p300/CBP HAT activity contributes to various diseases including cancer. Sequence alignments, enzymology experiments and inhibitor studies on p300/CBP have led to contradictory results about its catalytic mechanism and its structural relation to the Gcn5/PCAF and MYST HATs. Here we describe a high-resolution X-ray crystal structure of a semi-synthetic heterodimeric p300 HAT domain in complex with a bi-substrate inhibitor, Lys-CoA. This structure shows that p300/CBP is a distant cousin of other structurally characterized HATs, but reveals several novel features that explain the broad substrate specificity and preference for nearby basic residues. Based on this structure and accompanying biochemical data, we propose that p300/CBP uses an unusual 'hit-and-run' (Theorell-Chance) catalytic mechanism that is distinct from other characterized HATs. Several disease-associated mutations can also be readily accounted for by the p300 HAT structure. These studies pave the way for new epigenetic therapies involving modulation of p300/CBP HAT activity.