'The amino termini of histones extend from the nucleosomal core and are modified by acetyltransferases and deacetylases during the cell cycle These acetylation patterns may direct histone assembly and help regulate the unfolding and activity of genes

Histone acetylation in chromatin structure and transcription

Histone deacetylase (HDAC) inhibitors have been shown to be potent inducers of growth arrest, differentiation, and/or apoptotic cell death of transformed cells in vitro and in vivo. One class of HDAC inhibitors, hydroxamic acid-based hybrid polar compounds (HPCs), induce differentiation at micromolar or lower concentrations. Studies (x-ray crystallographic) showed that the catalytic site of HDAC has a tubular structure with a zinc atom at its base and that these HDAC inhibitors, such as suberoylanilide hydroxamic acid and trichostatin A, fit into this structure with the hydroxamic moiety of the inhibitor binding to the zinc. HDAC inhibitors cause acetylated histones to accumulate in both tumor and normal tissues, and this accumulation can be used as a marker of the biologic activity of the HDAC inhibitors. Hydroxamic acid-based HPCs act selectively to inhibit tumor cell growth at levels that have little or no toxicity for normal cells. These compounds also act selectively on gene expression, altering the expression of only about 2% of the genes expressed in cultured tumor cells. In general, chromatin fractions enriched in actively transcribed genes are also enriched in highly acetylated core histones, whereas silent genes are associated with nucleosomes with a low level of acetylation. However, HDACs can also acetylate proteins other than histones in nucleosomes. The role that these other targets play in the induction of cell growth arrest, differentiation, and/or apoptotic cell death has not been determined. Our working hypothesis is that inhibition of HDAC activity leads to the modulation of expression of a specific set of genes that, in turn, result in growth arrest, differentiation, and/or apoptotic cell death. The hydroxamic acid-based HPCs are potentially effective agents for cancer therapy and, possibly, cancer chemoprevention.

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Histone Deacetylase Inhibitors: Inducers of Differentiation or Apoptosis of Transformed Cells

Histone deacetylase inhibitors.

This invention relates to iminodiacetic acid and diamine hydroxamic acid derivatives, that are inhibitors of histone deacetylase (HDAC), and are useful in the prevention and/or treatment of cellular proliferative diseases, for example cancer, autoimmune, allergic and inflammatory diseases, diseases of the central nervous system (CNS) such as neurodegenerative diseases, and in the prevention and/or treatment of restenosis.

/pdf/histone-deacetylase-inhibitors-2kscxj8vod.pdf

Histone deacetylase inhibitors

Members of the Plasmodium falciparum var gene family encode clonally variant adhesins, which play an important role in the pathogenicity of tropical malaria. Here we employ a selective panning protocol to generate isogenic P.falciparum populations with defined adhesive phenotypes for CD36, ICAM-1 and CSA, expressing single and distinct var gene variants. This technique has established the framework for examining var gene expression, its regulation and switching. It was found that var gene switching occurs in situ. Ubiquitous transcription of all var gene variants appears to occur in early ring stages. However, var gene expression is tightly regulated in trophozoites and is exerted through a silencing mechanism. Transcriptional control is mutually exclusive in parasites that express defined adhesive phenotypes. In situ var gene switching is apparently mediated at the level of transcriptional initiation, as demonstrated by nuclear run-on analyses. Our results suggest that an epigenetic mechanism(s) is involved in var gene regulation.

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Antigenic variation in malaria: in situ switching, relaxed and mutually exclusive transcription of var genes during intra‐erythrocytic development in Plasmodium falciparum

A novel fungal metabolite, apicidin [cyclo(N-O-methyl-L-tryptophanyl-L -isoleucinyl-D-pipecolinyl-L-2-amino-8-oxodecanoyl)], that exhibits potent, broad spectrum antiprotozoal activity in vitro against Apicomplexan parasites has been identified. It is also orally and parenterally active in vivo against Plasmodium berghei malaria in mice. Many Apicomplexan parasites cause serious, life-threatening human and animal diseases, such as malaria, cryptosporidiosis, toxoplasmosis, and coccidiosis, and new therapeutic agents are urgently needed. Apicidin's antiparasitic activity appears to be due to low nanomolar inhibition of Apicomplexan histone deacetylase (HDA), which induces hyperacetylation of histones in treated parasites. The acetylation-deacetylation of histones is a thought to play a central role in transcriptional control in eukaryotic cells. Other known HDA inhibitors were also evaluated and found to possess antiparasitic activity, suggesting that HDA is an attractive target for the development of novel antiparasitic agents.

/pdf/apicidin-a-novel-antiprotozoal-agent-that-inhibits-parasite-5cla3iy5dh.pdf

Apicidin: A novel antiprotozoal agent that inhibits parasite histone deacetylase

Broad spectrum antiprotozoal agents that inhibit histone deacetylase: structure-activity relationships of apicidin. Part 2.

Broad spectrum antiprotozoal agents that inhibit histone deacetylase: structure-activity relationships of apicidin. Part 1

The present invention provides novel cyclic tetrapeptides useful in the treatment or prevention of protozoal diseases; in particular, the novel compounds are active against the causative pathogens in malaria, toxoplasmosis, and coccidiosis.

Christine Lange Cannova

Papers

Apicidin: A novel antiprotozoal agent that inhibits parasite histone deacetylase

Broad spectrum antiprotozoal agents that inhibit histone deacetylase: structure-activity relationships of apicidin. Part 2.

Broad spectrum antiprotozoal agents that inhibit histone deacetylase: structure-activity relationships of apicidin. Part 1

Antiprotozoal cyclic tetrapeptides

Gegen protozoen wirksamezyklische tetrapeptide