The Promoter of Rv0560c Is Induced by Salicylate and Structurally-Related Compounds in Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a major global health threat. During infection, bacteria are believed to encounter adverse conditions such as iron depletion. Mycobacteria synthesize iron-sequestering mycobactins, which are essential for survival in the host, via the intermediate salicylate. Salicylate is a ubiquitous compound which is known to induce a mild antibiotic resistance phenotype. In M. tuberculosis salicylate highly induces the expression of Rv0560c, a putative methyltransferase. We identified and characterized the promoter and regulatory elements of Rv0560c. PRv0560c activity was highly inducible by salicylate in a dose-dependent manner. The induction kinetics of PRv0560c were slow, taking several days to reach maximal activity, which was sustained over several weeks. Promoter activity could also be induced by compounds structurally related to salicylate, such as aspirin or para-aminosalicylic acid, but not by benzoate, indicating that induction is specific to a structural motif. The −10 and −35 promoter elements were identified and residues involved in regulation of promoter activity were identified in close proximity to an inverted repeat spanning the −35 promoter element. We conclude that Rv0560c expression is controlled by a yet unknown repressor via a highly-inducible promoter

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Feline low-grade alimentary lymphoma: an emerging entity and a potential animal model for human disease

Background: Low-grade alimentary lymphoma (LGAL) is characterised by the infiltration of neoplastic T-lymphocytes, typically in the small intestine. The incidence of LGAL has increased over the last ten years and it is now the most frequent digestive neoplasia in cats and comprises 60 to 75% of gastrointestinal lymphoma cases. Given that LGAL shares common clinical, paraclinical and ultrasonographic features with inflammatory bowel diseases, establishing a diagnosis is challenging. A review was designed to summarise current knowledge of the pathogenesis, diagnosis, prognosis and treatment of feline LGAL. Electronic searches of PubMed and Science Direct were carried out without date or language restrictions. Results: A total of 176 peer-reviewed documents were identified and most of which were published in the last twenty years. 130 studies were found from the veterinary literature and 46 from the human medicine literature. Heterogeneity of study designs and outcome measures made meta-analysis inappropriate. The pathophysiology of feline LGAL still needs to be elucidated, not least the putative roles of infectious agents, environmental factors as well as genetic events. The most common therapeutic strategy is combination treatment with prednisolone and chlorambucil, and prolonged remission can often be achieved. Developments in immunohistochemical analysis and clonality testing have improved the confidence of clinicians in obtaining a correct diagnosis between LGAL and IBD. The condition shares similarities with some diseases in humans, especially human indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. Conclusions: The pathophysiology of feline LGAL still needs to be elucidated and prospective studies as well as standardisation of therapeutic strategies are needed. A combination of conventional histopathology and immunohistochemistry remains the current gold-standard test, but clinicians should be cautious about reclassifying cats previously diagnosed with IBD to lymphoma on the basis of clonality testing. Importantly, feline LGAL could be considered to be a potential animal model for indolent digestive T-cell lymphoproliferative disorder, a rare condition in human medicine

Enigmazole Phosphomacrolides from the Marine Sponge Cinachyrella enigmatica

Enigmazole B (1) and four new analogues, cis-enigmazole B (2), dehydroenigmazole B (3), enigmimide B (4), and enigmimide A (5), were isolated from the marine sponge Cinachyrella enigmatica. Their planar structures were elucidated by detailed NMR and MS data analyses, which established 1–3 to be oxazole-substituted 18-membered phosphomacrolides, while 4 and 5 were oxazole ring-opened congeners. The relative and absolute configurations in 1 were determined by a combination of chemical transformations and spectroscopic analyses. Photooxidation of the oxazole moiety in 1 gave enigmimide B (4), thus establishing that 4 has the same absolute configuration of 1. Enigmazole B (1) along with analogues 2 and 3 showed cytotoxicity against murine IC-2 mast cells with IC50 values of 3.6–7.0 μM. The enigmimides (4 and 5) and dephosphoenigmazoles did not show cytotoxicity (IC50 > 10 μM), implying that both the oxazole moiety and the phosphate group are necessary for the cytotoxicity of the enigmazole class macrolides

Structural Elucidation and Synthesis of Eudistidine A: An Unusual Polycyclic Marine Alkaloid that Blocks Interaction of the Protein Binding Domains of p300 and HIF-1α

Low oxygen environments are a hallmark of solid tumors, and transcription of many hypoxia-responsive genes needed for survival under these conditions is regulated by the transcription factor HIF-1 (hypoxia-inducible factor 1). Activation of HIF-1 requires binding of its α-subunit (HIF-1α) to the transcriptional coactivator protein p300. Inhibition of the p300/HIF-1α interaction can suppress HIF-1 activity. A screen for inhibitors of the protein binding domains of p300 (CH1) and HIF-1α (C-TAD) identified an extract of the marine ascidian <i>Eudistoma</i> sp. as active. Novel heterocyclic alkaloids eudistidines A (<b>1</b>) and B (<b>2</b>) were isolated from the extract, and their structures assigned by spectroscopic analyses. They contain an unprecedented tetracyclic core composed of two pyrimidine rings fused with an imidazole ring. Eudistidine A (<b>1</b>) was synthesized in a concise four-step sequence featuring a condensation/cyclization reaction cascade between 4-(2-aminophenyl)­pyrimidin-2-amine (<b>3</b>) and 4-methoxy-phenylglyoxal (<b>4</b>), while eudistidine B (<b>2</b>) was synthesized in a similar fashion with glyoxylic acid (<b>5</b>) in place of <b>4</b>. Naturally occurring eudistidine A (<b>1</b>) effectively inhibited CH1/C-TAD binding with an IC₅₀ of 75 μM, and synthetic <b>1</b> had similar activity. The eudistidine A (<b>1</b>) scaffold, which can be synthesized in a concise, scalable manner, may provide potential therapeutic lead compounds or molecular probes to study p300/HIF-1α interactions and the role these proteins play in tumor response to low oxygen conditions. The unique structural scaffolds and functional group arrays often found in natural products make these secondary metabolites a rich source of new compounds that can disrupt critical protein–protein binding events

Screening and Biological Effects of Marine Pyrroloiminoquinone Alkaloids: Potential Inhibitors of the HIF-1α/p300 Interaction

Inhibition of the hypoxia-inducible factor 1α (HIF-1α) pathway by disrupting its association with the transcriptional coactivator p300 inhibits angiogenesis and tumor development. Development of HIF-1α/p300 inhibitors has been hampered by preclinical toxicity; therefore, we aimed to identify novel HIF-1α/p300 inhibitors. Using a cell-free assay designed to test compounds that block HIF-1α/p300 binding, 170 298 crude natural product extracts and prefractionated samples were screened, identifying 25 active extracts. One of these extracts, originating from the marine sponge <i>Latrunculia</i> sp., afforded six pyrroloiminoquinone alkaloids that were identified as positive hits (IC₅₀ values: 1–35 μM). Luciferase assays confirmed inhibition of HIF-1α transcriptional activity by discorhabdin B (<b>1</b>) and its dimer (<b>2</b>), 3-dihydrodiscorhabdin C (<b>3</b>), makaluvamine F (<b>5</b>), discorhabdin H (<b>8</b>), discorhabdin L (<b>9</b>), and discorhabdin W (<b>11</b>) in HCT 116 colon cancer cells (0.1–10 μM, <i>p</i> < 0.05). Except for <b>11</b>, all of these compounds also reduced HIF-1α transcriptional activity in LNCaP prostate cancer cells (0.1–10 μM, <i>p</i> < 0.05). These effects occurred at noncytotoxic concentrations (<50% cell death) under hypoxic conditions. At the downstream HIF-1α target level, compound <b>8</b> (0.5 μM) significantly decreased VEGF secretion in LNCaP cells (<i>p</i> < 0.05). In COLO 205 colon cancer cells no activity was shown in the luciferase or cytotoxicity assays. Pyrroloiminoquinone alkaloids are a novel class of HIF-1α inhibitors, which interrupt the protein–protein interaction between HIF-1α and p300 and consequently reduce HIF-related transcription

Characterization and Synthesis of Eudistidine C, a Bioactive Marine Alkaloid with an Intriguing Molecular Scaffold

An extract of <i>Eudistoma</i> sp. provided eudistidine C (<b>1</b>), a heterocyclic alkaloid with a novel molecular framework. Eudistidine C (<b>1</b>) is a racemic natural product composed of a tetracyclic core structure further elaborated with a <i>p</i>-methoxyphenyl group and a phenol-substituted aminoimidazole moiety. This compound presented significant structure elucidation challenges due to the large number of heteroatoms and fully substituted carbons. These issues were mitigated by application of a new NMR pulse sequence (LR-HSQMBC) optimized to detect four- and five-bond heteronuclear correlations and the use of computer-assisted structure elucidation software. Synthesis of eudistidine C (<b>1</b>) was accomplished in high yield by treating eudistidine A (<b>2</b>) with 4­(2-amino-1<i>H</i>-imidazol-5-yl)­phenol (<b>4</b>) in DMSO. Synthesis of eudistidine C (<b>1</b>) confirmed the proposed structure and provided material for further biological characterization. Treatment of <b>2</b> with various nitrogen heterocycles and electron-rich arenes provided a series of analogues (<b>5</b>–<b>10</b>) of eudistidine C. Chiral-phase HPLC resolution of epimeric eudistidine C provided (+)-(<i>R</i>)-eudistidine C (<b>1a</b>) and (−)-(<i>S</i>)-eudistidine C (<b>1b</b>). The absolute configuration of these enantiomers was assigned by ECD analysis. (−)-(<i>S</i>)-Eudistidine C (<b>1b</b>) modestly inhibited interaction between the protein binding domains of HIF-1α and p300. Compounds <b>1</b>, <b>2</b>, and <b>6</b>–<b>10</b> exhibited significant antimalarial activity against <i>Plasmodium falciparum</i>