scholarly journals Tetrahymena thermophila JMJD3 Homolog Regulates H3K27 Methylation and Nuclear Differentiation

2012 ◽  
Vol 11 (5) ◽  
pp. 601-614 ◽  
Author(s):  
Pei-Han Chung ◽  
Meng-Chao Yao
Keyword(s):  
Gene Expression ◽  
Tetrahymena Thermophila ◽  
Critical Role ◽  
Content Type ◽  
Chromatin Dynamics ◽  
H3k27 Methylation ◽  
Dna Elimination ◽  
Severe Reduction ◽  
Nuclear Development ◽  
Important Regulator

ABSTRACT Histone H3K27me3 modification is an important regulator for development and gene expression. In Tetrahymena thermophila , the complex chromatin dynamics of H3K27me3 marks during nuclear development suggested that an H3K27me3 demethylase might exist. Here, we report an H3K27me3 demethylase homolog, JMJ1 , in Tetrahymena . During conjugation, JMJ1 expression is upregulated and the protein is localized first in the parental macronucleus and then in the new macronucleus. In conjugating cells, knockdown of JMJ1 expression resulted in a severe reduction in the production of progeny, suggesting that JMJ1 is essential for Tetrahymena conjugation. Furthermore, knockdown of JMJ1 resulted in increased H3K27 trimethylation in the new macronucleus and reduced transcription of genes related to DNA elimination, while the DNA elimination process was also partially blocked. Knockdown of the H3K27 methyltransferase EZL2 but not that of EZL1 partially restored progeny production in JMJ1 -knockdown cells and reduced abnormal H3K27me3 accumulation in the new macronucleus. Taken together, these results demonstrate a critical role for JMJ1 in regulating H3K27me3 during conjugation and the importance of JMJ1 in regulating gene expression in the new macronucleus but not in regulating the formation of heterochromatin associated with programmed DNA deletion.

scholarly journals LIA4Encodes a Chromoshadow Domain Protein Required for Genomewide DNA Rearrangements in Tetrahymena thermophila

2014 ◽  
Vol 13 (10) ◽  
pp. 1300-1311 ◽  
Author(s):  
Scott A. Horrell ◽  
Douglas L. Chalker
Keyword(s):  
Critical Role ◽  
Dna Rearrangement ◽  
Rnai Machinery ◽  
Content Type ◽  
Heterochromatin Formation ◽  
H3k27 Methylation ◽  
Dna Elimination ◽  
Somatic Genome ◽  
Subsequent Elimination ◽  
Elimination Pathway

ABSTRACTExtensive DNA elimination occurs as part of macronuclear differentiation duringTetrahymenasexual reproduction. The identification of sequences to excise is guided by a specialized RNA interference (RNAi) machinery that targets the methylation of histone H3 lysine 9 (K9) and K27 on chromatin associated with these internal eliminated sequences (IESs). This modified chromatin is reorganized into heterochromatic subnuclear foci, which is a hallmark of their subsequent elimination. Here, we demonstrate that Lia4, a chromoshadow domain-containing protein, is an essential component in this DNA elimination pathway.LIA4knockout (ΔLIA4) lines fail to excise IESs from their developing somatic genome and arrest at a late stage of conjugation. Lia4 acts after RNAi-guided heterochromatin formation, as both H3K9 and H3K27 methylation are established. Nevertheless, withoutLIA4, these cells fail to form the heterochromatic foci associated with DNA rearrangement, and Lia4 accumulates in the foci, indicating that Lia4 plays a key role in their structure. These data indicate a critical role for Lia4 in organizing the nucleus duringTetrahymenamacronuclear differentiation.

scholarly journals The Pseudomonas aeruginosa PrrF Small RNAs Regulate Iron Homeostasis during Acute Murine Lung Infection

2017 ◽  
Vol 85 (5) ◽  
Author(s):  
Alexandria A. Reinhart ◽  
Angela T. Nguyen ◽  
Luke K. Brewer ◽  
Justin Bevere ◽  
Jace W. Jones ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Small Rnas ◽  
Iron Homeostasis ◽  
Critical Role ◽  
Opportunistic Pathogen ◽  
Lung Infection ◽  
Content Type ◽  
The Individual

ABSTRACT Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that requires iron for virulence. Iron homeostasis is maintained in part by the PrrF1 and PrrF2 small RNAs (sRNAs), which block the expression of iron-containing proteins under iron-depleted conditions. The PrrF sRNAs also promote the production of the Pseudomonas quinolone signal (PQS), a quorum sensing molecule that activates the expression of several virulence genes. The tandem arrangement of the prrF genes allows for expression of a third sRNA, PrrH, which is predicted to regulate gene expression through its unique sequence derived from the prrF1-prrF2 intergenic (IG) sequence (the PrrHIG sequence). Previous studies showed that the prrF locus is required for acute lung infection. However, the individual functions of the PrrF and PrrH sRNAs were not determined. Here, we describe a system for differentiating PrrF and PrrH functions by deleting the PrrHIG sequence [prrF(ΔHIG)]. Our analyses of this construct indicate that the PrrF sRNAs, but not PrrH, are required for acute lung infection by P. aeruginosa. Moreover, we show that the virulence defect of the ΔprrF1-prrF2 mutant is due to decreased bacterial burden during acute lung infection. In vivo analysis of gene expression in lung homogenates shows that PrrF-mediated regulation of genes for iron-containing proteins is disrupted in the ΔprrF1-prrF2 mutant during infection, while the expression of genes that mediate PrrF-regulated PQS production are not affected by prrF deletion in vivo. Combined, these studies demonstrate that regulation of iron utilization plays a critical role in P. aeruginosa's ability to survive during infection.

scholarly journals An Aminotransferase Is Responsible for the Deamination of the N-Terminal Leucine and Required for Formation of Oxazolone Ring A in Methanobactin of Methylosinus trichosporium OB3b

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Wenyu Gu ◽  
Bipin S. Baral ◽  
Alan A. DiSpirito ◽  
Jeremy D. Semrau
Keyword(s):  
Gene Expression ◽  
Gene Cluster ◽  
Wilson Disease ◽  
Critical Role ◽  
Broad Host Range ◽  
Copper Binding ◽  
Copper Uptake ◽  
Methylosinus Trichosporium ◽  
Content Type ◽  
Oxazolone Ring

ABSTRACT Gene expression in methanotrophs has been shown to be affected by the availability of a variety of metals, most notably copper-regulating expression of alternative forms of methane monooxygenase. A copper-binding compound, or chalkophore, called methanobactin plays a key role in copper uptake in methanotrophs. Methanobactin is a ribosomally synthesized and posttranslationally modified peptide (RiPP) with two heterocyclic rings with an associated thioamide for each ring, formed from X-Cys dipeptide sequences that bind copper. The gene coding for the precursor polypeptide of methanobactin, mbnA, is part of a gene cluster, but the role of other genes in methanobactin biosynthesis is unclear. To begin to elucidate the function of these genes, we constructed an unmarked deletion of mbnABCMN in Methylosinus trichosporium OB3b and then homologously expressed mbnABCM using a broad-host-range cloning vector to determine the function of mbnN, annotated as coding for an aminotransferase. Methanobactin produced by this strain was found to be substantially different from wild-type methanobactin in that the C-terminal methionine was missing and only one of the two oxazolone rings was formed. Rather, in place of the N-terminal 3-methylbutanoyl-oxazolone-thioamide group, a leucine and a thioamide-containing glycine (Gly-Ψ) were found, indicating that MbnN is used for deamination of the N-terminal leucine of methanobactin and that this posttranslational modification is critical for closure of the N-terminal oxazolone ring in M. trichosporium OB3b. These studies provide new insights into methanobactin biosynthesis and also provide a platform for understanding the function of other genes in the methanobactin gene cluster. IMPORTANCE Methanotrophs, microbes that play a critical role in the carbon cycle, are influenced by copper, with gene expression and enzyme activity changing as copper levels change. Methanotrophs produce a copper-binding compound, or chalkophore, called methanobactin for copper uptake, and methanobactin plays a key role in controlling methanotrophic activity. Methanobactin has also been shown to be effective in the treatment of Wilson disease, an autosomal recessive disorder where the human body cannot correctly assimilate copper. It is important to characterize the methanobactin biosynthesis pathway to understand how methanotrophs respond to their environment as well as to optimize the use of methanobactin for the treatment of copper-related diseases such as Wilson disease. Here we show that mbnN, encoding an aminotransferase, is involved in the deamination of the N-terminal leucine and necessary for the formation of one but not both of the heterocyclic rings in methanobactin that are responsible for copper binding.

scholarly journals Reduced SCD1 activity alters markers of fatty acid reesterification, glyceroneogenesis, and lipolysis in murine white adipose tissue and 3T3-L1 adipocytes

2017 ◽  
Vol 313 (3) ◽  
pp. C295-C304 ◽  
Author(s):  
Steven M. Dragos ◽  
Karl F. Bergeron ◽  
Frédérik Desmarais ◽  
Katherine Suitor ◽  
David C. Wright ◽  
...  
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
White Adipose Tissue ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Critical Role ◽  
Wild Type ◽  
Important Regulator ◽  
Specific Regulation

White adipose tissue (WAT) has a critical role in lipid handling. Previous work demonstrated that SCD1 is an important regulator of WAT fatty acid (FA) composition; however, its influence on the various interconnected pathways influencing WAT lipid handling remains unclear. Our objective was to investigate the role of SCD1 on WAT lipid handling using Scd1 knockout (KO) mice and SCD1-inhibited 3T3-L1 adipocytes by measuring gene, protein, and metabolite markers related to FA reesterification, glyceroneogenesis, and lipolysis. Triacylglycerol (TAG) content was higher in inguinal WAT (iWAT) from KO mice compared with wild-type, but significantly lower in epididymal WAT (eWAT). The SCD1 desaturation index was decreased in both WAT depots in KO mice. FA reesterification, as measured with a NEFA:glycerol ratio, was reduced in both WAT depots in KO mice, as well as SCD1-inhibited 3T3-L1 adipocytes. Pck1, Atgl, and Hsl gene expression was reduced in both WAT depots of KO mice, while Pck2 and Pdk4 gene expression showed depot-specific regulation. Pck1, Atgl, and Hsl gene expression was reduced, and phosphoenolpyruvate carboxykinase protein content was ablated, in SCD1-inhibited adipocytes. Our data provide evidence that SCD1 has a broad impact on WAT lipid handling by altering TAG composition in a depot-specific manner, reducing FA reesterification, and regulating markers of lipolysis and glyceroneogenesis.

scholarly journals Zygotic Expression of the Double-Stranded RNA Binding Motif Protein Drb2p Is Required for DNA Elimination in the Ciliate Tetrahymena thermophila

2011 ◽  
Vol 10 (12) ◽  
pp. 1648-1659 ◽  
Author(s):  
Jason A. Motl ◽  
Douglas L. Chalker
Keyword(s):  
Rna Binding ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Rna Binding Proteins ◽  
Chromosome Breakage ◽  
Binding Motif ◽  
Double Stranded Rna ◽  
Content Type ◽  
Dna Elimination ◽  
Genes Encoding

ABSTRACTDouble-stranded RNA binding motif (DSRM)-containing proteins play many roles in the regulation of gene transcription and translation, including some with tandem DSRMs that act in small RNA biogenesis. We report the characterization of the genes for double-stranded RNA binding proteins 1 and 2 (DRB1andDRB2), two genes encoding nuclear proteins with tandem DSRMs in the ciliateTetrahymena thermophila.Both proteins are expressed throughout growth and development but exhibit distinct peaks of expression, suggesting different biological roles. In support of this, we show that expression ofDRB2is essential for vegetative growth whileDRB1expression is not. During conjugation, Drb1p and Drb2p localize to distinct nuclear foci. Cells lacking allDRB1copies are able to produce viable progeny, although at a reduced rate relative to wild-type cells. In contrast, cells lacking germ lineDRB2copies, which thus cannot express Drb2p zygotically, fail to produce progeny, arresting late into conjugation. This arrest phenotype is accompanied by a failure to organize the essential DNA rearrangement protein Pdd1p into DNA elimination bodies and execute DNA elimination and chromosome breakage. These results implicate zygotically expressed Drb2p in the maturation of these nuclear structures, which are necessary for reorganization of the somatic genome.

scholarly journals The Transcription Factor StuA Regulates Central Carbon Metabolism, Mycotoxin Production, and Effector Gene Expression in the Wheat Pathogen Stagonospora nodorum

2010 ◽  
Vol 9 (7) ◽  
pp. 1100-1108 ◽  
Author(s):  
Simon V. S. IpCho ◽  
Kar-Chun Tan ◽  
Geraldine Koh ◽  
Joel Gummer ◽  
Richard P. Oliver ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Carbon Metabolism ◽  
Critical Role ◽  
Central Carbon Metabolism ◽  
Stagonospora Nodorum ◽  
Amino Acid Synthesis ◽  
Content Type ◽  
Central Carbon

ABSTRACT The Stagonospora nodorum StuA transcription factor gene SnStuA was identified by homology searching in the genome of the wheat pathogen Stagonospora nodorum. Gene expression analysis revealed that SnStuA transcript abundance increased throughout infection and in vitro growth to peak during sporulation. To investigate its role, the gene was deleted by homologous recombination. The growth of the resulting mutants was retarded on glucose compared to the wild-type growth, and the mutants also failed to sporulate. Glutamate as a sole carbon source restored the growth rate defect observed on glucose, although sporulation remained impaired. The SnstuA strains were essentially nonpathogenic, with only minor growth observed around the point of inoculation. The role of SnstuA was investigated using metabolomics, which revealed that this gene's product played a key role in regulating central carbon metabolism, with glycolysis, the TCA cycle, and amino acid synthesis all affected in the mutants. SnStuA was also found to positively regulate the synthesis of the mycotoxin alternariol. Gene expression studies on the recently identified effectors in Stagonospora nodorum found that SnStuA was a positive regulator of SnTox3 but was not required for the expression of ToxA. This study has uncovered a multitude of novel regulatory targets of SnStuA and has highlighted the critical role of this gene product in the pathogenicity of Stagonospora nodorum.

scholarly journals Role of ATG8 and Autophagy in Programmed Nuclear Degradation in Tetrahymena thermophila

2012 ◽  
Vol 11 (4) ◽  
pp. 494-506 ◽  
Author(s):  
Ming-Liang Liu ◽  
Meng-Chao Yao
Keyword(s):  
Fluorescent Protein ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Critical Role ◽  
Nuclear Periphery ◽  
Unicellular Eukaryote ◽  
Knockout Mutant ◽  
Content Type ◽  
Nuclear Degradation

ABSTRACT Autophagy is an evolutionarily conserved mechanism for the degradation of cellular components, but its role in enucleation during differentiation has not been established. Tetrahymena thermophila is a unicellular eukaryote with two functionally distinct nuclei, the somatic (macro-) and the germ line (micro-) nuclei. These nuclei are produced during sexual reproduction (conjugation), which involves differentiation and selective degradation of several specific nuclei. To examine the role of autophagy in nuclear degradation, we studied the function of two ATG8 genes in Tetrahymena . Through fluorescent protein tagging, we found that both proteins are targeted to degrading nuclei at specific stages, with some enrichment on the nuclear periphery, suggesting the formation of autophagosomes surrounding these nuclei. In addition, ATG8 knockout mutant cells showed a pronounced delay in nuclear degradation without apparently preventing the completion of other developmental events. This evidence provided direct support for a critical role for autophagy in programmed nuclear degradation. The results also showed differential roles for two ATG8 genes, with ATG8-65 playing a more significant role in starvation than ATG8-2 , although both are important in nuclear degradation.

A Review on Important Histone Acetyltransferase (HAT) Enzymes as Targets for Cancer Therapy

2019 ◽  
Vol 15 (2) ◽  
pp. 120-130
Author(s):  
Mohammad Ghanbari ◽  
Reza Safaralizadeh ◽  
Kiyanoush Mohammadi
Keyword(s):  
Gene Expression ◽  
Histone Acetyltransferase ◽  
Critical Role ◽  
Cancer Treatments ◽  
Control Of Gene Expression ◽  
Post Translational Modifications ◽  
Therapeutic Drugs ◽  
The Status ◽  
Acetyl Group ◽  
Increase Gene Expression

At the present time, cancer is one of the most lethal diseases worldwide. There are various factors involved in the development of cancer, including genetic factors, lifestyle, nutrition, and so on. Recent studies have shown that epigenetic factors have a critical role in the initiation and development of tumors. The histone post-translational modifications (PTMs) such as acetylation, methylation, phosphorylation, and other PTMs are important mechanisms that regulate the status of chromatin structure and this regulation leads to the control of gene expression. The histone acetylation is conducted by histone acetyltransferase enzymes (HATs), which are involved in transferring an acetyl group to conserved lysine amino acids of histones and consequently increase gene expression. On the basis of similarity in catalytic domains of HATs, these enzymes are divided into different groups such as families of GNAT, MYST, P300/CBP, SRC/P160, and so on. These enzymes have effective roles in apoptosis, signaling pathways, metastasis, cell cycle, DNA repair and other related mechanisms deregulated in cancer. Abnormal activation of HATs leads to uncontrolled amplification of cells and incidence of malignancy signs. This indicates that HAT might be an important target for effective cancer treatments, and hence there would be a need for further studies and designing of therapeutic drugs on this basis. In this study, we have reviewed the important roles of HATs in different human malignancies.

scholarly journals Modulation of Chicken Intestinal Immune Gene Expression by Small Cationic Peptides as Feed Additives during the First Week Posthatch

2013 ◽  
Vol 20 (9) ◽  
pp. 1440-1448 ◽  
Author(s):  
Michael H. Kogut ◽  
Kenneth J. Genovese ◽  
Haiqi He ◽  
Christina L. Swaggerty ◽  
Yiwei Jiang
Keyword(s):  
Gene Expression ◽  
Proinflammatory Cytokines ◽  
Proinflammatory Cytokine ◽  
Feed Additives ◽  
Feed Additive ◽  
Cationic Peptides ◽  
Type I ◽  
Immune Gene ◽  
Content Type ◽  
Functional Efficiency

ABSTRACTWe have been investigating modulation strategies tailored around the selective stimulation of the host's immune system as an alternative to direct targeting of microbial pathogens by antibiotics. One such approach is the use of a group of small cationic peptides (BT) produced by a Gram-positive soil bacterium,Brevibacillus texasporus. These peptides have immune modulatory properties that enhance both leukocyte functional efficiency and leukocyte proinflammatory cytokine and chemokine mRNA transcription activitiesin vitro. In addition, when provided as a feed additive for just 4 days posthatch, BT peptides significantly induce a concentration-dependent protection against cecal and extraintestinal colonization bySalmonella entericaserovar Enteritidis. In the present studies, we assessed the effects of feeding BT peptides on transcriptional changes on proinflammatory cytokines, inflammatory chemokines, and Toll-like receptors (TLR) in the ceca of broiler chickens with and withoutS. Enteritidis infection. After feeding a BT peptide-supplemented diet for the first 4 days posthatch, chickens were then challenged withS. Enteritidis, and intestinal gene expression was measured at 1 or 7 days postinfection (p.i.) (5 or 11 days of age). Intestinal expression of innate immune mRNA transcripts was analyzed by quantitative real-time PCR (qRT-PCR). Analysis of relative mRNA expression showed that a BT peptide-supplemented diet did not directly induce the transcription of proinflammatory cytokine, inflammatory chemokine, type I/II interferon (IFN), or TLR mRNA in chicken cecum. However, feeding the BT peptide-supplemented diet primed cecal tissue for increased (P≤ 0.05) transcription of TLR4, TLR15, and TLR21 upon infection withS. Enteritidis on days 1 and 7 p.i. Likewise, feeding the BT peptides primed the cecal tissue for increased transcription of proinflammatory cytokines (interleukin 1β [IL-1β], IL-6, IL-18, type I and II IFNs) and inflammatory chemokine (CxCLi2) in response toS. Enteritidis infection 1 and 7 days p.i. compared to the chickens fed the basal diet. These small cationic peptides may prove useful as alternatives to antibiotics as local immune modulators in neonatal poultry by providing prophylactic protection againstSalmonellainfections.

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