Mutations in the acetylation hotspots of Rbl2 are associated with increased risk of breast cancer.

Retinoblastoma like protein-2 (Rbl2) is functionally regulated by phosphorylation and acetylation. Previously, we demonstrated that lysine K1083 (K1079 in human Rbl2) is a potential target for acetylation but its functional role remains elusive. We investigated alterations in human Rbl2 gene specifically targeting exons 19-22 harbouring acetylatable residues i.

In vitro phosphorylation and acetylation of the murine pocket protein Rb2/p130.

The retinoblastoma protein (pRb) and the related proteins Rb2/p130 and 107 represent the "pocket protein" family of cell cycle regulators. A key function of these proteins is the cell cycle dependent modulation of E2F-regulated genes. The biological activity of these proteins is controlled by acetylation and phosphorylation in a cell cycle dependent manner.

Cell cycle-dependent acetylation of Rb2/p130 in NIH3T3 cells.

The retinoblastoma protein (pRb) and the pRb-related proteins, p130 and p107, form the 'pocket protein' family of cell cycle regulatory factors. A well characterized function of these proteins is the cell cycle-dependent regulation of E2F-responsive genes. The biological activity of pocket proteins is regulated by phosphorylation and for the founding member pRb it has been shown that acetylation also has an important role in modulating its function during the cell cycle.

Novel insights into the functional role of three protein arginine methyltransferases in Aspergillus nidulans.

Protein arginine methylation has been implicated in different cellular processes including transcriptional regulation by the modification of histone proteins. Here we demonstrate significant in vitro activities and multifaceted specificities of Aspergillus protein arginine methyltransferases (PRMTs) and we provide evidence for a role of protein methylation in mechanisms of oxidative stress response. We have isolated all three Aspergillus PRMTs from fungal extracts and could assign significant histone specificity to RmtA and RmtC.

A novel motif in fungal class 1 histone deacetylases is essential for growth and development of Aspergillus.

Acetylation of the N-terminal tails of core histones is an important regulatory mechanism in eukaryotic organisms. In filamentous fungi, little is known about the enzymes that modify histone tails. However, it is increasingly evident that histone deacetylases and histone acetyltransferases are critical factors for the regulation of genes involved in fungal pathogenicity, stress response, and production of secondary metabolites such as antibiotics or fungal toxins.

Cell cycle dependent role of HDAC1 for proliferation control through modulating ribosomal DNA transcription.

Ribosome biogenesis and ribosomal DNA transcription are closely correlated with the growth and proliferation of cells, with these processes being under tight epigenetic control. We have investigated the effect of ectopically expressed murine HDAC1 in reporter assays, on ribosomal DNA transcription, cell cycle progression and proliferation in transfected mammalian cells. Ectopically expressed mHDAC1 represses transcription in ribosomal reporter assays driven by ribosomal promoter elements in NIH3T3 cells as well as Cos-7 cells.

Histone modifications and chromatin dynamics: a focus on filamentous fungi.

The readout of the genetic information of eukaryotic organisms is significantly regulated by modifications of DNA and chromatin proteins. Chromatin alterations induce genome-wide and local changes in gene expression and affect a variety of processes in response to internal and external signals during growth, differentiation, development, in metabolic processes, diseases, and abiotic and biotic stresses. This review aims at summarizing the roles of histone H1 and the acetylation and methylation of histones in filamentous fungi and links this knowledge to the huge body of data from other systems.

Synthesis and biological evaluation of 2-, 3-, and 4-acylaminocinnamyl-N-hydroxyamides as novel synthetic HDAC inhibitors.

A new series of 2-, 3-, and 4-acylaminocinnamyl-N-hydroxyamides 1-3 have been prepared, and their anti-HDAC (against maize HD2, HD1-B, and HD1-A enzymes) activities have been assessed. Cinnamyl-hydroxyamides bearing acylamino substituents at the C2 position of the benzene ring (compounds 1a-g) showed very low HDAC inhibiting activities, with IC(50) values in the high micromolar range. By shifting the same acylamino groups from C2 to C3 (compounds 2a-g) as well as C4 (compounds 3a-f) position of the benzene ring, a number of highly potent HDAC inhibitors have been obtained.

Acetylation of UBF changes during the cell cycle and regulates the interaction of UBF with RNA polymerase I.

The upstream binding factor UBF, an activator of RNA polymerase I transcription, is posttranslationally modified by phosphorylation and acetylation. We found that in NIH3T3 cells, UBF is acetylated in S-phase but not in G1-phase. To assess the role of acetylation in regulation of UBF activity, we have established an NIH3T3 cell line that inducibly overexpresses HDAC1.

HdaA, a major class 2 histone deacetylase of Aspergillus nidulans, affects growth under conditions of oxidative stress.

Histone deacetylases (HDACs) catalyze the removal of acetyl groups from the epsilon-amino group of distinct lysine residues in the amino-terminal tail of core histones. Since the acetylation status of core histones plays a crucial role in fundamental processes in eukaryotic organisms, such as replication and regulation of transcription, recent research has focused on the enzymes responsible for the acetylation/deacetylation of core histones. Very recently, we showed that HdaA, a member of the Saccharomyces cerevisiae HDA1-type histone deacetylases, is a substantial contributor to total HDAC activity in the filamentous fungus Aspergillus nidulans.

Class II (IIa)-selective histone deacetylase inhibitors. 1. Synthesis and biological evaluation of novel (aryloxopropenyl)pyrrolyl hydroxyamides.

Chemical manipulations performed on aroyl-pyrrolyl-hydroxyamides (APHAs) led to (aryloxopropenyl)pyrrolyl hydroxamates 2a-w, and their inhibition against maize HDACs and their class I or class II HDAC selectivity were determined. In particular, from these studies some benzene meta-substituted compounds emerged as highly class II (IIa)-selective HDAC inhibitors, the most selective being the 3-chloro- and 3-fluoro-substituted compounds 2c (SI = 71.4) and2f (SI = 176.

Mad1 function in cell proliferation and transcriptional repression is antagonized by cyclin E/CDK2.

The transcription factors of the Myc/Max/Mad network play essential roles in the regulation of cellular behavior. Mad1 inhibits cell proliferation by recruiting an mSin3-corepressor complex that contains histone deacetylase activity. Here we demonstrate that Mad1 is a potent inhibitor of the G(1) to S phase transition, a function that requires Mad1 to heterodimerize with Max and to bind to the corepressor complex.

Histone methyltransferases in Aspergillus nidulans: evidence for a novel enzyme with a unique substrate specificity.

We have studied enzymes involved in histone arginine methylation in the filamentous fungus Aspergillus nidulans. Three distinct protein arginine methyltransferases (PRMTs) could be identified, which all exhibit intrinsic histone methyltransferase activity when expressed as glutathione S-transferase (GST) fusion proteins. Two of these proteins, termed RmtA (arginine methyltransferase A) and RmtC, reveal significant sequence homology to the well-characterized human proteins PRMT1 and PRMT5, respectively.

A plant dialect of the histone language.

The genome contains all the information needed to build an organism. However, during differentiation and development, additional epigenetic information determines the functional state of cells and tissues. This epigenetic information can be introduced by cytosine methylation and by marking nucleosomal histones.

A new amidohydrolase from Bordetella or Alcaligenes strain FB188 with similarities to histone deacetylases.

The full-length gene encoding the histone deacetylase (HDAC)-like amidohydrolase (HDAH) from Bordetella or Alcaligenes (Bordetella/Alcaligenes) strain FB188 (DSM 11172) was cloned using degenerate primer PCR combined with inverse-PCR techniques and ultimately expressed in Escherichia coli. The expressed enzyme was biochemically characterized and found to be similar to the native enzyme for all properties examined. Nucleotide sequence analysis revealed an open reading frame of 1,110 bp which encodes a polypeptide with a theoretical molecular mass of 39 kDa.

3-(4-Aroyl-1-methyl-1H-pyrrol-2-yl)-N-hydroxy-2-propenamides as a new class of synthetic histone deacetylase inhibitors. 3. Discovery of novel lead compounds through structure-based drug design and docking studies.

Aroyl-pyrrole-hydroxy-amides (APHAs) are a new class of synthetic HDAC inhibitors recently described by us. Through three different docking procedures we designed, synthesized, and tested two new isomers of APHA lead compound 3-(4-benzoyl-1-methyl-1H-pyrrol-2-yl)-N-hydroxy-2-propenamide (1), compounds 3 and 4, characterized by different insertions of benzoyl and propenoylhydroxamate groups onto the pyrrole ring. Biological activities of 3 and 4 were predicted by computational tools up to 617-fold more potent than that of 1 against HDAC1; thus, 3 and 4 were synthesized and tested against both mouse HDAC1 and maize HD2 enzymes.

3-(4-Aroyl-1-methyl-1H-2-pyrrolyl)-N-hydroxy-2-propenamides as a new class of synthetic histone deacetylase inhibitors. 2. Effect of pyrrole-C2 and/or -C4 substitutions on biological activity.

Previous SAR studies (Part 1: Mai, A.; et al. J.

Discovery of (aryloxopropenyl)pyrrolyl hydroxyamides as selective inhibitors of class IIa histone deacetylase homologue HD1-A.

Chemical manipulations performed on aroyl pyrrolyl hydroxyamides, a new class of HDAC inhibitors previously reported by us, led to (aryloxopropenyl)pyrrolyl hydroxyamides 3a-g. Such compounds, showing better inhibitory activity against maize HD1-A than HD1-B (two homologues of mammalian class IIa and I HDACs, respectively), are the first class of IIa-selective inhibitors (fold selectivity: 7-78). They could be useful as tools for probing the biology of these enzymes and eventually as new anticancer agents with low toxicity.

Regulation and processing of maize histone deacetylase Hda1 by limited proteolysis.

A maize histone deacetylase gene was identified as a homolog of yeast Hda1. The predicted protein corresponds to a previously purified maize deacetylase that is active as a protein monomer with a molecular weight of 48,000 and is expressed in all tissues of germinating embryos. Hda1 is synthesized as an enzymatically inactive protein with an apparent molecular weight of 84,000 that is processed to the active 48-kD form by proteolytic removal of the C-terminal part, presumably via a 65-kD intermediate.

Histone deacetylases in fungi: novel members, new facts.

Acetylation is the most prominent modification on core histones that strongly affects nuclear processes such as DNA replication, DNA repair and transcription. Enzymes responsible for the dynamic equilibrium of histone acetylation are histone acetyltransferases (HATs) and histone deacetylases (HDACs). In this paper we describe the identification of novel HDACs from the filamentous fungi Aspergillus nidulans and the maize pathogen Cochliobolus carbonum.

3-(4-Aroyl-1-methyl-1H-2-pyrrolyl)-N-hydroxy-2-alkylamides as a new class of synthetic histone deacetylase inhibitors. 1. Design, synthesis, biological evaluation, and binding mode studies performed through three different docking procedures.

Recently we reported a novel series of hydroxamates, called 3-(4-aroyl-1H-2-pyrrolyl)-N-hydroxy-2-propenamides (APHAs), acting as HDAC inhibitors (Massa, S.; et al. J.

Molecular identification of PpHDAC1, the first histone deacetylase fron the slime mold Physarum polycephalum.

The dynamic state of post-translational acetylation of eukaryotic histones is maintained by histone acetyltransferases (HATs) and histone deacetylases (HDACs). HATs and HDACs have been shown to be components of various regulatory protein complexes in the cell. Their enzymatic activities, intracellular localization and substrate specificities are regulated in a complex, cell cycle related manner.

Structure-activity relationships on phenylalanine-containing inhibitors of histone deacetylase: in vitro enzyme inhibition, induction of differentiation, and inhibition of proliferation in Friend leukemic cells.

Inhibitors of histone deacetylases (HDACs) are a new class of anticancer agents that affect gene regulation. We had previously reported the first simple synthetic HDAC inhibitors with in vitro activity at submicromolar concentrations. Here, we present structure-activity data on modifications of a phenylalanine-containing lead compound including amino acid amides as well as variations of the amino acid part.

Binding mode analysis of 3-(4-benzoyl-1-methyl-1H-2-pyrrolyl)-N-hydroxy-2-propenamide: a new synthetic histone deacetylase inhibitor inducing histone hyperacetylation, growth inhibition, and terminal cell differentiation.

The binding mode of 3-(4-aroyl-1H-2-pyrrolyl)-N-hydroxy-2-propenamides 1a-c, belonging to a recently reported class of synthetic histone deacetylase (HDAC) inhibitors (Massa, S.; et al. J.

An inhibitor-resistant histone deacetylase in the plant pathogenic fungus Cochliobolus carbonum.

We have partially purified and characterized histone deacetylases of the plant pathogenic fungus Cochliobolus carbonum. Depending on growth conditions, this fungus produces HC-toxin, a specific histone deacetylase inhibitor. Purified enzymes were analyzed by immunoblotting, by immunoprecipitation, and for toxin sensitivity.