Functional organization of hsp70 cluster in camel (Camelus dromedarius) and other mammals

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e27205, doi:10.1371/journal.pone.0027205.Heat shock protein 70 (Hsp70) is a molecular chaperone providing tolerance to heat and other challenges at the cellular and organismal levels. We sequenced a genomic cluster containing three hsp70 family genes linked with major histocompatibility complex (MHC) class III region from an extremely heat tolerant animal, camel (Camelus dromedarius). Two hsp70 family genes comprising the cluster contain heat shock elements (HSEs), while the third gene lacks HSEs and should not be induced by heat shock. Comparison of the camel hsp70 cluster with the corresponding regions from several mammalian species revealed similar organization of genes forming the cluster. Specifically, the two heat inducible hsp70 genes are arranged in tandem, while the third constitutively expressed hsp70 family member is present in inverted orientation. Comparison of regulatory regions of hsp70 genes from camel and other mammals demonstrates that transcription factor matches with highest significance are located in the highly conserved 250-bp upstream region and correspond to HSEs followed by NF-Y and Sp1 binding sites. The high degree of sequence conservation leaves little room for putative camel-specific regulatory elements. Surprisingly, RT-PCR and 5′/3′-RACE analysis demonstrated that all three hsp70 genes are expressed in camel's muscle and blood cells not only after heat shock, but under normal physiological conditions as well, and may account for tolerance of camel cells to extreme environmental conditions. A high degree of evolutionary conservation observed for the hsp70 cluster always linked with MHC locus in mammals suggests an important role of such organization for coordinated functioning of these vital genes.This work was supported by the Russian Foundation for Basic Research, project 09-04-00643 and 09-04-00660, project from ‘‘Genofond dynamics’’ program, and Grant of the Program of Molecular and Cellular Biology RAN to Dr. Evgen’ev; and by the Ministry of Education and Science of Russian Federation (State contract 14.740.11.0757 and Russia President Grant to young scientists MK-1418.2010.4. The research was supported by State Contract N16.552.11.7034 of Ministry of Education and Science

Xenobiotic-induced activation of human aryl hydrocarbon receptor target genes in Drosophila is mediated by the epigenetic chromatin modifiers

Aryl hydrocarbon receptor (AHR) is the key transcription factor that controls animal development and various adaptive processes. The AHR\u27s target genes are involved in biodegradation of endogenous and exogenous toxins, regulation of immune response, organogenesis, and neurogenesis. Ligand binding is important for the activation of the AHR signaling pathway. Invertebrate AHR homologs are activated by endogenous ligands whereas vertebrate AHR can be activated by both endogenous and exogenous ligands (xenobiotics). Several studies using mammalian cultured cells have demonstrated that transcription of the AHR target genes can be activated by exogenous AHR ligands, but little is known about the effects of AHR in a living organism. Here, we examined the effects of human AHR and its ligands using transgenic Drosophila lines with an inducible human AhR gene. We found that exogenous AHR ligands can increase as well as decrease the transcription levels of the AHR target genes, including genes that control proliferation, motility, polarization, and programmed cell death. This suggests that AHR activation may affect the expression of gene networks that could be critical for cancer progression and metastasis. Importantly, we found that AHR target genes are also controlled by the enzymes that modify chromatin structure, in particular components of the epigenetic Polycomb Repressive complexes 1 and 2. Since exogenous AHR ligands (alternatively - xenobiotics) and small molecule inhibitors of epigenetic modifiers are often used as pharmaceutical anticancer drugs, our findings may have significant implications in designing new combinations of therapeutic treatments for oncological diseases. © Akishina et al

Combination of hypomorphic mutations of the Drosophila homologues of aryl hydrocarbon receptor and nucleosome assembly protein family genes disrupts morphogenesis, memory and detoxification

Aryl hydrocarbon receptor is essential for biological responses to endogenous and exogenous toxins in mammals. Its Drosophila homolog spineless plays an important role in fly morphogenesis. We have previously shown that during morphogenesis spineless genetically interacts with CG5017 gene, which encodes a nucleosome assembly factor and may affect cognitive function of the fly. We now demonstrate synergistic interactions of spineless and CG5017 in pathways controlling oxidative stress response and long-term memory formation in Drosophila melanogaster. Oxidative stress was induced by low doses of X-ray irradiation of flies carrying hypomorphic mutation of spineless, mutation of CG5017, and their combination. To determine the sensitivity of these mutants to pharmacological modifiers of the irradiation effect, we irradiated flies growing on standard medium supplemented by radiosensitizer furazidin and radioprotector serotonin. The effects of irradiation were investigated by analyzing leg and antenna morphological structures and by using real-time PCR to measure mRNA expression levels for spineless, Cyp6g1 and Gst-theta genes. We also examined long-term memory in these mutants using conditioned courtship suppression paradigm. Our results show that the interaction of spineless and CG5017 is important for regulation of morphogenesis, long-term memory formation, and detoxification during oxidative stress. Since spineless and CG5017 are evolutionary conserved, these results must be considered when evaluating the risk of combining similar mutations in other organisms, including humans

Ferro-electric phase transition in a polar liquid and the nature of \lambda-transition in supercooled water

We develop a series of approximations to calculate free energy of a polar liquid. We show that long range nature of dipole interactions between the molecules leads to para-electric state instability at low temperatures and to a second-order phase transition. We establish the transition temperature, T_{c}, both within mean field and ring diagrams approximation and show that the ferro-electric transition may play an important role explaining a number of peculiar properties of supercooled water, such as weak singularity of dielectric constant as well as to a large extent anomalous density behavior. Finally we discuss the role of fluctuations, shorter range forces and establish connections with phenomenological models of polar liquids.Comment: 5 pages, 1 eps figure, density anomaly at T=4C analysis adde

Parent-of-origin effects on nuclear chromatin organization and behavior in a Drosophila model for Williams–Beuren Syndrome

Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D chromatin architecture and (3) impact of parent-specific miRNAs. Additionally, the shaping of cognitive phenotypes in parents depends on both learning acquisition and forgetting, or memory erasure. These processes are independent and controlled by different signal cascades: the first is cAMPdependent, the second relies on actin remodeling by small GTPase Rac1 – LIMK1 (LIM-kinase 1). Simple experimental model systems such as Drosophila help probe the causes and consequences leading to human neurocognitive pathologies. Recently, we have developed a Drosophila model for Williams–Beuren Syndrome (WBS): a mutant agnts3 of the agnostic locus (X:11AB) harboring the dlimk1 gene. The agnts3 mutation drastically increases the frequency of ectopic contacts (FEC) in specific regions of intercalary heterochromatin, suppresses learning/memory and affects locomotion. As is shown in this study, the polytene X chromosome bands in reciprocal hybrids between agnts3 and the wild type strain Berlin are heterogeneous in modes of FEC regulation depending either on maternal or paternal gene origin. Bioinformatic analysis reveals that FEC between X:11AB and the other X chromosome bands correlates with the occurrence of short (~30 bp) identical DNA fragments partly homologous to Drosophila 372-bp satellite DNA repeat. Although learning acquisition in a conditioned courtship suppression paradigm is similar in hybrids, the middle-term memory formation shows patroclinic inheritance. Seemingly, this depends on changes in miR-974 expression. Several parameters of locomotion demonstrate heterosis. Our data indicate that the agnts3 locus is capable of trans-regulating gene activity via POEs on the chromatin nuclear organization, thereby affecting behavior

Nucleologenesis in the Caenorhabditis elegans Embryo

In the Caenorhabditis elegans nematode, the oocyte nucleolus disappears prior to fertilization. We have now investigated the re-formation of the nucleolus in the early embryo of this model organism by immunostaining for fibrillarin and DAO-5, a putative NOLC1/Nopp140 homolog involved in ribosome assembly. We find that labeled nucleoli first appear in somatic cells at around the 8-cell stage, at a time when transcription of the embryonic genome begins. Quantitative analysis of radial positioning showed the nucleolus to be localized at the nuclear periphery in a majority of early embryonic nuclei. At the ultrastructural level, the embryonic nucleolus appears to be composed of a relatively homogenous core surrounded by a crescent-shaped granular structure. Prior to embryonic genome activation, fibrillarin and DAO-5 staining is seen in numerous small nucleoplasmic foci. This staining pattern persists in the germline up to the ∼100-cell stage, until the P4 germ cell divides to give rise to the Z2/Z3 primordial germ cells and embryonic transcription is activated in this lineage. In the ncl-1 mutant, which is characterized by increased transcription of rDNA, DAO-5-labeled nucleoli are already present at the 2-cell stage. Our results suggest a link between the activation of transcription and the initial formation of nucleoli in the C. elegans embryo

Противоопухолевая активность кураксина CBL0137 на моделях острых лейкозов in vitro

Background. Curaxin CBL0137 is a novel non-genotoxic compound with anti-cancer activity based on CBL0137 ability of non-covalent interaction with DNA causing histone chaperone FACT relocation. Anti-cancer activity of this drug was demonstrated previously on the wide panel of solid cancer models in vitro and in vivo.Objectives. Estimation of anticancer effects of CBL0137 on the acute myeloblastic leukemia cells (THP-1) and acute lymphoblastic leukemia (CCRF-CEM).Materials and methods. CBL0137 cytotoxicity was analyzed using the MTT test, the effects on the cell cycle and the induction of apoptosis was assessed by flow cytometry, the activity of signaling pathways in cells treated with CBL0137 was determined by real-time polymerase chain reaction.Results. Cell treatment with CBL0137 led to cell cycle arrest and apoptosis induction. In the study of CBL0137 effect on target gene clusters of 10 signal transduction pathways involved in the pathogenesis of acute leukemia we have showed that CBL0137 inhibited the expression of down-stream genes of WNT and Hedgehog signaling in both cell lines. In THP-1 cells we also observed the inhibition of the expression of PPARγ target and hypoxia-activated genes. In CCRF-CEM cells CBL0137 also induced the expression of Notch signaling target genes.Conclusion. The antitumor activity of CBL0137 was demonstrated on acute leukemia cell cultures, the drug possesses cytotoxicity, causes cell cycle arrest and activation of apoptosis. Significant changes in the expression of efferent gene clusters of several signaling pathways were observed in the cells treated with CBL0137.Введение. Кураксин CBL0137 – новое негенотоксичное соединение, обладающее противоопухолевой активностью, в основе которой лежит способность препарата нековалентно взаимодействовать с ДНК, вызывая транслокацию гистонового шаперона FACT в хроматиновую фракцию. Ранее противоопухолевая активность этого агента была продемонстрирована относительно широкого спектра солидных опухолей in vitro и in vivo.Цель исследования – изучение противоопухолевой активности CBL0137 в отношении клеток острого миелобластного лейкоза (THP-1) и острого лимфобластного лейкоза (CCRF-CEM) in vitro.Материалы и методы. Для определения цитотоксичности CBL0137 использовали МТТ-тест, влияние на клеточный цикл и индукцию апоптоза оценивали с помощью проточной цитофлуориметрии, активность функционирования сигнальных путей при действии на клетки CBL0137 определяли с помощью полимеразной цепной реакции в реальном времени.Результаты. Обработка клеток CBL0137 приводит к аресту клеточного цикла и активации апоптоза. При исследовании влияния CBL0137 на кластеры таргетных генов 10 сигнальных путей, вовлеченных в онкогенез острых лейкозов, его ингибирующее действие было выявлено для сигнальных путей WNT и Hedgehog в обеих клеточных линиях. В клеточной линии THP-1 также наблюдалось ингибирование эфферентных генов PPARγ и генов, активирующихся при гипоксии. В клетках CCRF-CEM при действии CBL0137, кроме того, наблюдалось усиление экспрессии всех исследованных таргетных генов сигнального пути Notch.Заключение. На культурах клеток острых лейкозов продемонстрирована противоопухолевая активность CBL0137, препарат обладает цитотоксичностью, вызывает арест клеточного цикла и активацию апоптоза. При действии CBL0137 наблюдаются значительные изменения в экспрессии кластеров эфферентных генов сразу нескольких сигнальных путей

New Assembly, Reannotation and Analysis of the Entamoeba histolytica Genome Reveal New Genomic Features and Protein Content Information

Entamoeba histolytica is an anaerobic parasitic protozoan that causes amoebic dysentery. The parasites colonize the large intestine, but under some circumstances may invade the intestinal mucosa, enter the bloodstream and lead to the formation of abscesses such amoebic liver abscesses. The draft genome of E. histolytica, published in 2005, provided the scientific community with the first comprehensive view of the gene set for this parasite and important tools for elucidating the genetic basis of Entamoeba pathogenicity. Because complete genetic knowledge is critical for drug discovery and potential vaccine development for amoebiases, we have re-examined the original draft genome for E. histolytica. We have corrected the sequence assembly, improved the gene predictions and refreshed the functional gene assignments. As a result, this effort has led to a more accurate gene annotation, and the discovery of novel features, such as the presence of genome segmental duplications and the close association of some gene families with transposable elements. We believe that continuing efforts to improve genomic data will undoubtedly help to identify and characterize potential targets for amoebiasis control, as well as to contribute to a better understanding of genome evolution and pathogenesis for this parasite