scholarly journals Inactivation of the Stress- and Starvation-Inducible gls24 Operon Has a Pleiotrophic Effect on Cell Morphology, Stress Sensitivity, and Gene Expression inEnterococcus faecalis

2000 ◽  
Vol 182 (16) ◽  
pp. 4512-4520 ◽  
Author(s):  
Jean-Christophe Giard ◽  
Alain Rince ◽  
Herve Capiaux ◽  
Yanick Auffray ◽  
Axel Hartke
Keyword(s):  
Gene Expression ◽  
Bile Salts ◽  
Morphological Changes ◽  
Tap Water ◽  
Stress Protein ◽  
Biological Significance ◽  
Stress Sensitivity ◽  
Northern Analysis ◽  
Alkaline Stress ◽  
Wild Type

ABSTRACT Enterococcus faecalis induces the synthesis of at least 42 proteins during 24 h of glucose starvation. Because of its induction during carbohydrate and complete starvation (incubation in tap water) and CdCl2 and bile salts stresses, one of these proteins (Gls24) was qualified as a “general stress protein” and was analyzed at the molecular level. Its corresponding gene,gls24, seems to be the penultimate gene of an operon composed, altogether, of six open reading frames (ORFs). The ORF preceding gls24 (orf4) showed very strong identity with gls24. The deduced polypeptides of these two genes showed similarity with a 20-kDa hypothetical protein fromLactococcus lactis and an alkaline stress protein fromStaphylococcus aureus with no previously known biological significance. Data from the operon sequence and Northern analysis led to the conclusions that (i) gls24 possesses its own promoter which is especially induced at the onset of starvation and (ii) the operon promoter is stress inducible in exponential-phase cells. A mutation in the gls24 gene led to a severe reduction of growth rate and reduction of survival against 0.3% bile salts in the 24-h-starved cells compared to the wild-type strain. Moreover, the chain length of the mutant is significantly reduced during growth. These results argue strongly for a role of the protein Gls24 and/or GlsB in morphological changes and in stress tolerance inE. faecalis. Comparison of two-dimensional protein gels from wild-type cells with those from gls24 mutant cells revealed a pleiotropic effect of the mutation on gene expression. At least nine proteins were present in larger amounts in the mutant. For six of them, the corresponding N-terminal microsequence has been obtained. Three of these sequences map in genes coding forl-lactate dehydrogenase, lipoamide dehydrogenase, and pyruvate decarboxylase, all involved in pyruvate metabolism.

Oral immunization with a dam mutant of Yersinia pseudotuberculosis protects against plague

Microbiology ◽  
2005 ◽  
Vol 151 (6) ◽  
pp. 1919-1926 ◽  
Author(s):  
Victoria L. Taylor ◽  
Richard W. Titball ◽  
Petra C. F. Oyston
Keyword(s):  
Gene Expression ◽  
Bile Salts ◽  
Yersinia Pseudotuberculosis ◽  
Lethal Dose ◽  
Oral Immunization ◽  
Wild Type ◽  
Gene Encoding ◽  
Serovar Typhimurium ◽  
Dna Adenine Methylase ◽  
Methylase Gene

Inactivation of the gene encoding DNA adenine methylase (dam) has been shown to attenuate some pathogens such as Salmonella enterica serovar Typhimurium and is a lethal mutation in others such as Yersinia pseudotuberculosis strain YPIII. In this study the dam methylase gene in Yersinia pseudotuberculosis strain IP32953 was inactivated. Unlike the wild-type, DNA isolated from the mutant could be digested with MboI, which is consistent with an altered pattern of DNA methylation. The mutant was sensitive to bile salts but not to 2-aminopurine. The effect of dam inactivation on gene expression was examined using a DNA microarray. In BALB/c mice inoculated orally or intravenously with the dam mutant, the median lethal dose (MLD) was at least 106-fold higher than the MLD of the wild-type. BALB/c mice inoculated with the mutant were protected against a subcutaneous challenge with 100 MLDs of Yersinia pestis strain GB and an intravenous challenge with 300 MLDs of Y. pseudotuberculosis IP32953.

scholarly journals A Nonessential HP1-Like Protein Affects Starvation-Induced Assembly of Condensed Chromatin and Gene Expression in Macronuclei of Tetrahymena thermophila

1999 ◽  
Vol 19 (5) ◽  
pp. 3624-3634 ◽  
Author(s):  
Hui Huang ◽  
James F. Smothers ◽  
Emily A. Wiley ◽  
C. David Allis
Keyword(s):  
Gene Expression ◽  
Tetrahymena Thermophila ◽  
Morphological Changes ◽  
Condensed Chromatin ◽  
Induced Response ◽  
Wild Type ◽  
Eukaryotic Genes ◽  
Associated Proteins ◽  
Induced Genes ◽  
Dense Chromatin

ABSTRACT Heterochromatin represents a specialized chromatin environment vital to both the repression and expression of certain eukaryotic genes. One of the best-studied heterochromatin-associated proteins isDrosophila HP1. In this report, we have disrupted all somatic copies of the Tetrahymena HHP1 gene, which encodes an HP1-like protein, Hhp1p, in macronuclei (H. Huang, E. A. Wiley, R. C. Lending, and C. D. Allis, Proc. Natl. Acad. Sci. USA 95:13624–13629, 1998). Unlike the Drosophila HP1 gene,HHP1 is not essential in Tetrahymena spp., and during vegetative growth no clear phenotype is observed in cells lacking Hhp1p (ΔHHP1). However, during a shift to nongrowth conditions, the survival rate of ΔHHP1 cells is reduced compared to that of wild-type cells. Upon starvation, Hhp1p becomes hyperphosphorylated concomitant with a reduction in macronuclear volume and an increase in the size of electron-dense chromatin bodies; neither of these morphological changes occurs in the absence of Hhp1p. Activation of two starvation-induced genes (ngoA and CyP) is significantly reduced in ΔHHP1 cells while, in contrast, the expression of several growth-related or constitutively expressed genes is comparable to that in wild-type cells. These results suggest that Hhp1p functions in the establishment and/or maintenance of a specialized condensed chromatin environment that facilitates the expression of certain genes linked to a starvation-induced response.

scholarly journals Transcriptional milestones in Dictyostelium development

2021 ◽  
Author(s):  
Mariko Katoh-Kurasawa ◽  
Karin Hrovatin ◽  
Shigenori Hirose ◽  
Amanda Webb ◽  
Hsing-I Ho ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Background ◽  
Web Application ◽  
Morphological Changes ◽  
Single Cells ◽  
Sequencing Analysis ◽  
Wild Type ◽  
Chromosomal Dna ◽  
Gene Annotations ◽  
Developmental Conditions

Development of the social amoeba Dictyostelium discoideum begins by starvation of single cells and ends in multicellular fruiting bodies 24 hours later. These major morphological changes are accompanied by sweeping gene expression changes, encompassing nearly half of the 13,000 genes in the genome. To explore the relationships between the transcriptome and developmental morphogenesis, we performed time-series RNA-sequencing analysis of the wild type and 20 mutant strains with altered morphogenesis. These strains exhibit arrest at different developmental stages, accelerated development, or terminal morphologies that are not typically seen in the wild type. Considering eight major morphological transitions, we identified 1,371 milestone genes whose expression changes sharply between two consecutive transitions. We also identified 1,099 genes as members of 21 regulons, which are groups of genes that remain coordinately regulated despite the genetic, temporal, and developmental perturbations in the dataset. The gene annotations in these milestones and regulons validate known transitions and reveal several new physiological and functional transitions during development. For example, we found that DNA replication genes are co-regulated with cell division genes, so they are co-expressed in mid-development even though chromosomal DNA is not replicated at that time. Altogether, the dataset includes 486 transcriptional profiles, across developmental and genetic conditions, that can be used to identify new relationships between gene expression and developmental processes and to improve gene annotations. We demonstrate the utility of this resource by showing that the cycles of aggregation and disaggregation observed in allorecognition-defective mutants involve a dedifferentiation process. We also show unexpected variability and sensitivity to genetic background and developmental conditions in two commonly used genes, act6 and act15, and robustness of the coaA gene. Finally, we propose that gpdA should be used as a standard for mRNA quantitation because it is less sensitive to genetic background and developmental conditions than commonly used standards. The dataset is available for democratized exploration without the need for programming skills through the web application dictyExpress and the data mining environment Orange.

scholarly journals The C. elegans gene pag-3 is homologous to the zinc finger proto-oncogene gfi-1

Development ◽  
1997 ◽  
Vol 124 (10) ◽  
pp. 2063-2073 ◽  
Author(s):  
Y. Jia ◽  
G. Xie ◽  
J.B. McDermott ◽  
E. Aamodt
Keyword(s):  
Gene Expression ◽  
Zinc Finger ◽  
Motor Neurons ◽  
Nonsense Mutation ◽  
Zinc Finger Protein ◽  
Protein Sequencing ◽  
Null Alleles ◽  
Northern Analysis ◽  
Wild Type ◽  
Sister Cells

Mutations in the Caenorhabditis elegans gene pag-3 result in misexpression of touch receptor-specific genes in the BDU interneurons and in motility defects. We cloned pag-3 and found that the gene encodes a C2H2-type zinc finger protein related to the mammalian GFI-1 protein. Sequencing of the three pag-3 alleles showed that two apparent null alleles encode a nonsense mutation before the zinc fingers and a missense mutation in the fourth zinc finger that changes a coordinating histidine to a tyrosine. The third allele contains a nonsense mutation in the N-terminal region but is not a null allele. Northern analysis showed that a single pag-3 transcript of about 1.6 kb is present in embryos and L1, L2 and L3 larvae. pag-3 message levels were about twofold higher in pag-3 mutants than in wild-type animals, which suggested that pag-3 may negatively regulate its own expression. pag-3lacZ fusion genes were expressed in the BDU interneurons, the touch neurons, 11 VA and 11 VB ventral cord motor neurons, two AVF interneurons and in unidentified neurons of the retrovesicular ganglion. The BDU neurons and the ALM touch neurons are lineal sister cells in the AB.a lineage and the VA and VB motor neurons are lineal sister cells in the AB.p lineage. The VA motor neurons are required for backward movement and the VB motor neurons are required for forward movement. Mosaic analysis showed that the wild-type pag-3 gene is required in the AB.p lineage for coordinated movement and in the AB.a lineage to suppress touch neuron gene expression in the BDU neurons. Because pag-3 is expressed in both the BDU neurons and in the touch neurons, another protein(s) not expressed in the touch neurons may interact with pag-3 to repress touch neuron gene expression in the BDU neurons. Alternatively, another protein in the touch receptor cells may inactivate PAG-3 and allow expression of the touch receptor program. These results show that pag-3 is a temporally regulated gene that is expressed early in development and functions in multiple types of neurons. They also strongly suggest that the PAG3 protein is a DNA-binding protein with properties similar to the mammalian proto-oncogene product GFI-1.

Frequent BRAF V600E Mutations Are Identified in CD207+ Cells in LCH Lesions, but BRAF Status does not Correlate with Clinical Presentation of Patients or Transcriptional Profiles of CD207+ Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1372-1372 ◽  
Author(s):  
Tricia L Peters ◽  
Tsz-Kwong Chris Man ◽  
Jeremy Price ◽  
Renelle George ◽  
Phaik Har Lim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Conflicts Of Interest ◽  
Expression Profiles ◽  
Biological Significance ◽  
Braf V600e ◽  
Cell Of Origin ◽  
Wild Type ◽  
Braf Mutations ◽  
Clinical Difference ◽  
The Impact

Abstract Abstract 1372 Background: Very little is known about the cell of origin or the pathogenesis of LCH. There remains debate regarding LCH as a malignant disorder or the result of immune dysregulation. While multiple studies in the past failed to identify significant genetic lesions, an activating mutation (V600E) in the serine/threonine kinase BRAF was recently described in LCH biopsy samples (Badalian-Very et al., 2010). Objective: This study was designed to evaluate the frequency of BRAF mutations in LCH lesions, to identify the cells within the lesions carrying the mutation, and to evaluate the clinical and biological significance of the mutation. Design/Methods: Fresh LCH biopsy samples were collected, cells were sorted into CD3+ and CD207+ fractions, and RNA was purified then amplified into cDNA. Sanger sequencing as well as BRAF allele-specific PCR were performed for each sample. Categorical clinical data was compared to BRAF genotype to evaluate clinical significance of the mutation. Transcriptomes of CD207+ cells were also compared (wild-type BRAF vs V600E) with the Affymetrix U133Plus2.0 platform to determine the impact of the BRAF mutation on global gene expression. Results: The BRAF V600E mutation was consistently identified in cDNA generated from CD207+ cells in 17 of 32 (52%) LCH biopsy samples. Only the wild-type allele was detected in purified T (CD3+) cells from LCH lesions, control epidermal (CD207+) Langerhans cells, and control tonsil T (CD3+) cells. In two cases of recurrent disease, BRAF status was consistent in the presenting and the relapse CD207+ cells: wild-type BRAF in one case and V600E BRAF in another. However, mutation status did not correlate significantly with age (p=0.6), single lesion vs multifocal/systemic (p=1.0), or future recurrent/refractory disease (p=0.2) in this series. Furthermore, unsupervised clustering gene expression profiles CD207+ cells (wild-type BRAF vs V600E) did not segregate datasets based on BRAF status. Using standard statistical analysis, there were no genes identified as significantly up- or down-regulated as a result of the V600E mutation. Conclusion: The BRAF V600E point mutation is the first reproducible molecular abnormality identified in LCH. In this study, we validate the observation that it occurs with high frequency, and definitively localize the pathologic CD207+ cell as the source of the mutation in LCH lesions. Interestingly, while the frequency of the mutation implies some functional significance, in this series there is no statistically significant clinical difference between patients with wild-type or mutated BRAF lesions, and the transcriptomes of LCH CD207+ cells with wild-type and V600E BRAF are indistinguishable. It is possible that the mutation affects LCH pathogenesis at earlier stages in tumorigenesis, or there may be other routes of Ras pathway activation in LCH lesions with wild-type BRAF. While the role for BRAF in LCH pathogenesis remains to be defined, this is an important molecular foothold from which to investigate the biology of LCH. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The AML-associated K313 mutation enhances C/EBPα activity by leading to C/EBPα overexpression

2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Ian Edward Gentle ◽  
Isabel Moelter ◽  
Mohamed Tarek Badr ◽  
Konstanze Döhner ◽  
Michael Lübbert ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Culture ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activity ◽  
Target Gene ◽  
Wild Type ◽  
Elevated Expression ◽  
Factor C ◽  
Acute Myeloid

AbstractMutations in the transcription factor C/EBPα are found in ~10% of all acute myeloid leukaemia (AML) cases but the contribution of these mutations to leukemogenesis is incompletely understood. We here use a mouse model of granulocyte progenitors expressing conditionally active HoxB8 to assess the cell biological and molecular activity of C/EBPα-mutations associated with human AML. Both N-terminal truncation and C-terminal AML-associated mutations of C/EBPα substantially altered differentiation of progenitors into mature neutrophils in cell culture. Closer analysis of the C/EBPα-K313-duplication showed expansion and prolonged survival of mutant C/EBPα-expressing granulocytes following adoptive transfer into mice. C/EBPα-protein containing the K313-mutation further showed strongly enhanced transcriptional activity compared with the wild-type protein at certain promoters. Analysis of differentially regulated genes in cells overexpressing C/EBPα-K313 indicates a strong correlation with genes regulated by C/EBPα. Analysis of transcription factor enrichment in the differentially regulated genes indicated a strong reliance of SPI1/PU.1, suggesting that despite reduced DNA binding, C/EBPα-K313 is active in regulating target gene expression and acts largely through a network of other transcription factors. Strikingly, the K313 mutation caused strongly elevated expression of C/EBPα-protein, which could also be seen in primary K313 mutated AML blasts, explaining the enhanced C/EBPα activity in K313-expressing cells.

scholarly journals Growth, Development, and Gene Expression in a Persistent Streptococcus gordonii Biofilm

2003 ◽  
Vol 71 (8) ◽  
pp. 4759-4766 ◽  
Author(s):  
Keeta S. Gilmore ◽  
Pravina Srinivas ◽  
Darrin R. Akins ◽  
Kenneth L. Hatter ◽  
Michael S. Gilmore
Keyword(s):  
Gene Expression ◽  
Biofilm Formation ◽  
Bacterial Population ◽  
Morphological Changes ◽  
Expression Patterns ◽  
Nutrient Flux ◽  
Gene Expression Patterns ◽  
Significant Shift ◽  
Streptococcus Gordonii ◽  
Growth Development

ABSTRACT A model for the protracted (30-day) colonization of smooth surfaces by Streptococcus gordonii that incorporates the nutrient flux that occurs in the oral cavity was developed. This model was used to characterize the biphasic expansion of the adherent bacterial population, which corresponded with the emergence of higher-order architectures characteristic of biofilms. Biofilm formation by S. gordonii was observed to be influenced by the presence of simple sugars including sucrose, glucose, and fructose. Real-time PCR was used to quantify changes in expression of S. gordonii genes known or thought to be involved in biofilm formation. Morphological changes were accompanied by a significant shift in gene expression patterns. The majority of S. gordonii genes examined were observed to be downregulated in the biofilm phase. Genes found to be upregulated in the biofilm state were observed to encode products related to environmental sensing and signaling.

Cell cycle arrest and astrocytic differentiation resulting from PTEN expression in glioma cells

1999 ◽  
Vol 91 (5) ◽  
pp. 822-830 ◽  
Author(s):  
Jun-ichi Adachi ◽  
Katsumi Ohbayashi ◽  
Tomonari Suzuki ◽  
Tomio Sasaki
Keyword(s):  
Expression System ◽  
Biological Significance ◽  
Glioma Cells ◽  
Genetic Alterations ◽  
Pten Expression ◽  
Human Glioma ◽  
Wild Type ◽  
Content Type ◽  
Astrocytic Differentiation ◽  
Fine Print

Object. Genetic alterations of the PTEN gene (also known as MMAC1 or TEP1) have frequently been identified in high-grade gliomas, indicating that inactivation of PTEN plays a crucial role in human glioma progression. The aim of this study was to assess the biological significance of PTEN inactivation in the development of glioma.Methods. The authors introduced wild-type PTEN complementary DNA into four human glioma cell lines (T98G, U-251MG, U-87MG, and A172) containing endogenous aberrant PTEN alleles. The number of colonies transfected with the wild-type PTEN was reduced to 15 to 32% of those found after transfection of a control vector, suggesting growth suppression by the exogenous PTEN. To analyze phenotypic alterations produced by PTEN expression, T98G-derived clones with inducible PTEN expression were further established using a tetracycline-regulated inducible gene expression system. Induction of PTEN expression suppressed the in vitro growth of T98G cells with accumulation of G1 phase cells. Furthermore, when cells were cultured in the presence of the extracellular matrix (ECM), PTEN expression caused distinct morphological changes, with multiple and elongated cytoplasmic processes similar to those of normal astrocytes. The level of glial fibrillary acidic protein, an intermediate protein specifically expressed in differentiated astrocytes, was upregulated concomitantly.Conclusions. These findings strongly indicate that exogenous PTEN expression inhibits the proliferation of glioma cells by inducing G1 arrest and elicits astrocytic differentiation in the presence of the ECM. Inactivation of PTEN would play an important role in the enhancement of unregulated growth of undifferentiated glioma cells.

scholarly journals Effects of the domestic thyroid stimulating hormone receptor (TSHR) variant on the hypothalamic-pituitary-thyroid axis and behavior in chicken

Genetics ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
Amir Fallahshahroudi ◽  
Martin Johnsson ◽  
Enrico Sorato ◽  
S J Kumari A Ubhayasekera ◽  
Jonas Bergquist ◽  
...  
Keyword(s):  
Gene Expression ◽  
Hormone Receptor ◽  
Thyroid Stimulating Hormone ◽  
Phenotypic Traits ◽  
Wild Type ◽  
Data Set ◽  
Red Junglefowl ◽  
Pituitary Thyroid Axis ◽  
And Behavior ◽  
Stimulating Hormone

Abstract Domestic chickens are less fearful, have a faster sexual development, grow bigger, and lay more eggs than their primary ancestor, the red junglefowl. Several candidate genetic variants selected during domestication have been identified, but only a few studies have directly linked them with distinct phenotypic traits. Notably, a variant of the thyroid stimulating hormone receptor (TSHR) gene has been under strong positive selection over the past millennium, but it’s function and mechanisms of action are still largely unresolved. We therefore assessed the abundance of the domestic TSHR variant and possible genomic selection signatures in an extensive data set comprising multiple commercial and village chicken populations as well as wild-living extant members of the genus Gallus. Furthermore, by mean of extensive backcrossing we introgressed the wild-type TSHR variant from red junglefowl into domestic White Leghorn chickens and investigated gene expression, hormone levels, cold adaptation, and behavior in chickens possessing either the wild-type or domestic TSHR variant. While the domestic TSHR was the most common variant in all studied domestic populations and in one of two red junglefowl population, it was not detected in the other Gallus species. Functionally, the individuals with the domestic TSHR variant had a lower expression of the TSHR in the hypothalamus and marginally higher in the thyroid gland than wild-type TSHR individuals. Expression of TSHB and DIO2, two regulators of sexual maturity and reproduction in birds, was higher in the pituitary gland of the domestic-variant chickens. Furthermore, the domestic variant was associated with higher activity in the open field test. Our findings confirm that the spread of the domestic TSHR variant is limited to domesticated chickens, and to a lesser extent, their wild counterpart, the red junglefowl. Furthermore, we showed that effects of genetic variability in TSHR mirror key differences in gene expression and behavior previously described between the red junglefowl and domestic chicken.

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