RESUMEN
A series of bicyclic pyrazole carboxamides was synthesized and tested for inhibitory activity against the class III deacetylase sirtuin enzymes. Moderate to low micromolar inhibitory activities were obtained against SIRT1 and SIRT2. These bicyclic pyrazole compounds represent a new class of sirtuin inhibitors with a preference for SIRT1 over SIRT2.
Asunto(s)
Compuestos Bicíclicos con Puentes/química , Pirazoles/química , Sirtuina 1/antagonistas & inhibidores , Sirtuina 2/antagonistas & inhibidores , Sitios de Unión , Dominio Catalítico , Cristalografía por Rayos X , Evaluación Preclínica de Medicamentos , Simulación de Dinámica Molecular , Unión Proteica , Pirazoles/síntesis química , Pirazoles/metabolismo , Sirtuina 1/metabolismo , Sirtuina 2/metabolismo , Relación Estructura-ActividadRESUMEN
Acetyltransferase complexes of the MYST family with distinct substrate specificities and functions maintain a conserved association with different ING tumor suppressor proteins. ING complexes containing the HBO1 acetylase are a major source of histone H3 and H4 acetylation in vivo and play critical roles in gene regulation and DNA replication. Here, our molecular dissection of HBO1/ING complexes unravels the protein domains required for their assembly and function. Multiple PHD finger domains present in different subunits bind the histone H3 N-terminal tail with a distinct specificity toward lysine 4 methylation status. We show that natively regulated association of the ING4/5 PHD domain with HBO1-JADE determines the growth inhibitory function of the complex, linked to its tumor suppressor activity. Functional genomic analyses indicate that the p53 pathway is a main target of the complex, at least in part through direct transcription regulation at the initiation site of p21/CDKN1A. These results demonstrate the importance of ING association with MYST acetyltransferases in controlling cell proliferation, a regulated link that accounts for the reported tumor suppressor activities of these complexes.
Asunto(s)
Proliferación Celular , Histona Acetiltransferasas/metabolismo , Línea Celular , Histona Acetiltransferasas/química , Histonas/química , Histonas/metabolismo , Humanos , Estructura Terciaria de Proteína , Proteínas Supresoras de Tumor/química , Proteínas Supresoras de Tumor/metabolismo , Quinasas p21 Activadas/química , Quinasas p21 Activadas/metabolismoRESUMEN
The HBO1 HAT protein is the major source of histone H4 acetylation in vivo and has been shown to play critical roles in gene regulation and DNA replication. A distinctive characteristic of HBO1 HAT complexes is the presence of three PHD finger domains in two different subunits: tumor suppressor proteins ING4/5 and JADE1/2/3. Biochemical and functional analyses indicate that these domains interact with histone H3 N-terminal tail region, but with a different specificity toward its methylation status. Their combinatorial action is essential in regulating chromatin binding and substrate specificity of HBO1 complexes, as well as cell growth. Importantly, localization analyses on the human genome indicate that HBO1 complexes are enriched throughout the coding regions of genes, supporting a role in transcription elongation. These results underline the importance and versatility of PHD finger domains in regulating chromatin association and histone modification crosstalk within a single protein complex.
Asunto(s)
Cromatina/metabolismo , Proteínas de Unión al ADN/metabolismo , Histona Acetiltransferasas/metabolismo , Histonas/metabolismo , Acetilación , Sitios de Unión , Células Cultivadas , Proteínas de Unión al ADN/genética , Células HeLa , Histona Acetiltransferasas/genética , Histonas/genética , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Humanos , Metilación , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismoRESUMEN
Members of the ING family of tumor suppressors regulate cell cycle progression, apoptosis, and DNA repair as important cofactors of p53. ING1 and ING3 are stable components of the mSin3A HDAC and Tip60/NuA4 HAT complexes, respectively. We now report the purification of the three remaining human ING proteins. While ING2 is in an HDAC complex similar to ING1, ING4 associates with the HBO1 HAT required for normal progression through S phase and the majority of histone H4 acetylation in vivo. ING5 fractionates with two distinct complexes containing HBO1 or nucleosomal H3-specific MOZ/MORF HATs. These ING5 HAT complexes interact with the MCM helicase and are essential for DNA replication to occur during S phase. Our data also indicate that ING subunits are crucial for acetylation of chromatin substrates. Since INGs, HBO1, and MOZ/MORF contribute to oncogenic transformation, the multisubunit assemblies characterized here underscore the critical role of epigenetic regulation in cancer development.