scholarly journals The role of transcriptional repressor activity of LexA in salt-stress responses of the cyanobacterium Synechocystis sp. PCC 6803

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kosuke Takashima ◽  
Syota Nagao ◽  
Ayumi Kizawa ◽  
Takehiro Suzuki ◽  
Naoshi Dohmae ◽  
...  
Keyword(s):  
Gene Expression ◽  
Salt Stress ◽  
Posttranslational Modification ◽  
Environmental Changes ◽  
Heterotrophic Bacteria ◽  
Fine Tuning ◽  
Oligomeric State ◽  
Digital Switching ◽  
Pcc 6803

Abstract Different from typical LexA repressors in heterotrophic bacteria exerting SOS response by auto-cleavage, cyanobacterial LexAs, especially that of Synechocystis sp. PCC 6803 (S.6803), have been suggested be involved in regulation of a number of genes related to various cellular processes, rather than the typical SOS regulon. When and how cyanobacterial LexAs are triggered to regulate its target genes have remained unknown. In this study, we found the profound repressing effect of LexA on salt-stress inducible genes in S.6803. The repressing activity of LexA was likely to persist during salt stress and the salt response of these genes was mainly achieved by other regulators than LexA, suggesting that the physiological role of LexA is fine-tuning of gene expression in response to environmental changes. Although the amount and oligomeric state of LexA were unchanged upon salt stress, two-dimensional electrophoresis and liquid chromatography-tandem mass spectrometry analyses detected a change in posttranslational modification in a small fraction of LexA molecules, possibly dephosphorylation of Ser173, after 30 min upon the upshift in salt concentration. Activity of LexA in S.6803 may be under gradual control by posttranslational modification to fine-tune gene expression, which is contrasted with the digital switching-off regulation by auto-cleavage in heterotrophic bacteria.

scholarly journals Roles of Elongator Dependent tRNA Modification Pathways in Neurodegeneration and Cancer

Genes ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 19 ◽  
Author(s):  
Harmen Hawer ◽  
Alexander Hammermeister ◽  
Keerthiraju Ravichandran ◽  
Sebastian Glatt ◽  
Raffael Schaffrath ◽  
...  
Keyword(s):  
Gene Expression ◽  
Human Disease ◽  
Messenger Rna ◽  
Environmental Changes ◽  
Mrna Translation ◽  
Regulatory Control ◽  
Trna Modification ◽  
Positive Role ◽  
Trna Modifications

Transfer RNA (tRNA) is subject to a multitude of posttranscriptional modifications which can profoundly impact its functionality as the essential adaptor molecule in messenger RNA (mRNA) translation. Therefore, dynamic regulation of tRNA modification in response to environmental changes can tune the efficiency of gene expression in concert with the emerging epitranscriptomic mRNA regulators. Several of the tRNA modifications are required to prevent human diseases and are particularly important for proper development and generation of neurons. In addition to the positive role of different tRNA modifications in prevention of neurodegeneration, certain cancer types upregulate tRNA modification genes to sustain cancer cell gene expression and metastasis. Multiple associations of defects in genes encoding subunits of the tRNA modifier complex Elongator with human disease highlight the importance of proper anticodon wobble uridine modifications (xm5U34) for health. Elongator functionality requires communication with accessory proteins and dynamic phosphorylation, providing regulatory control of its function. Here, we summarized recent insights into molecular functions of the complex and the role of Elongator dependent tRNA modification in human disease.

scholarly journals Role of HSP90 in Salt Stress Tolerance via Stabilization and Regulation of Calcineurin

2000 ◽  
Vol 20 (24) ◽  
pp. 9262-9270 ◽  
Author(s):  
Jun Imai ◽  
Ichiro Yahara
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Salt Stress ◽  
Stress Tolerance ◽  
Normal Level ◽  
Immune Complexes ◽  
Salt Stress Tolerance ◽  
Stressed Cells ◽  
Calcineurin Activity

ABSTRACT The role of HSP90 in stress tolerance was investigated inSaccharomyces cerevisiae. Cells showing 20-fold overexpression of Hsc82, an HSP90 homologue in yeast, were hypersensitive to high-NaCl or H-LiCl stresses. Hsc82-overexpressing cells appeared similar to calcineurin-defective cells in salt sensitivity and showed reduced levels of calcineurin-dependent gene expression. Co-overexpression of Cna2, the catalytic subunit of calcineurin, suppressed the hypersensitivity. Cna2 and Hsc82 coimmunoprecipitated from control cells grown under normal conditions but not from stressed cells. In contrast, coimmunoprecipitation was detected with Hsc82-overexpressing cells even after exposure to stresses. Cna2 immune complexes from stressed control cells showed a significant level of calcineurin activity, whereas those from stressed Hsc82-overexpressing cells did not. Treatment of extracts from Hsc82-overexpressing cells with Ca2+-calmodulin increased the calcineurin activity associated with Cna2 immune complexes. Geldanamycin, an inhibitor of HSP90 abolished the coimmunoprecipitation but did not activate calcineurin. When the expression level of Hsc82 decreased to below 30% of the normal level, cells also became hypersensitive to salt stress. In these cells, the amount of Cna2 was reduced, likely as a result of degradation. The present results showed that Hsc82 binds to and stabilizes Cna2 and that dissociation of Cna2 from Hsc82 is necessary for its activation.

scholarly journals Fatty acids regulate the expression of lipoprotein lipase gene and activity in preadipose and adipose cells

1996 ◽  
Vol 314 (2) ◽  
pp. 541-546 ◽  
Author(s):  
Ez-Zoubir AMRI ◽  
Lydia TEBOUL ◽  
Christian VANNIER ◽  
Paul-André GRIMALDI ◽  
Gérard AILHAUD
Keyword(s):  
Gene Expression ◽  
Fatty Acids ◽  
Lipoprotein Lipase ◽  
Fine Tuning ◽  
Lipase Gene ◽  
Lpl Gene ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Adipose Cells

During fasting, a reduction in lipoprotein lipase (LPL) activity has been observed in rat fat pad with no change in enzyme mass, whereas LPL mRNA and synthesis are increased, suggesting that insulin and/or fatty acids (FA) regulate LPL activity post-translationaly [Doolittle, Ben-Zeev, Elovson, Martin and Kirchgessner (1990) J. Biol. Chem. 265, 4570–4577]. To examine the role of FA, either preadipose Ob1771 cells or Ob1771 and 3T3-F442A adipose cells were exposed to long-chain FA and to 2-bromopalmitate, a non-metabolized FA. A rapid (2–8 h) and dose-dependent increase (up to 6-fold) in LPL mRNA occurred, primarily due to increased transcription, which is accompanied by a decrease (down to 4-fold) in LPL cellular activity. Under these conditions, secretion of active LPL was nearly abolished. Removal of FA led to full recovery of LPL activity. LPL gene expression in 3T3-C2 fibroblasts was not affected by FA treatment. However fatty acid-activated receptor transfected-3T3-C2 cells, which show FA responsiveness, had increased LPL gene expression upon FA addition. LPL synthesis and cellular content appeared unaffected by FA treatment, whereas secretion of LPL was inhibited. These results indicate that FA regulate the post-translational processing of LPL. It is proposed that the regulation of LPL activity by FA is important with regard to the fine-tuning of FA entry into adipocytes during fasting/feeding periods.

scholarly journals Reduction of Spermidine Content Resulting from Inactivation of Two Arginine Decarboxylases Increases Biofilm Formation in Synechocystis sp. Strain PCC 6803

2018 ◽  
Vol 200 (9) ◽  
Author(s):  
Kota Kera ◽  
Tatsuya Nagayama ◽  
Kei Nanatani ◽  
Chika Saeki-Yamoto ◽  
Akira Tominaga ◽  
...  
Keyword(s):  
Salt Stress ◽  
Biofilm Formation ◽  
Heterotrophic Bacteria ◽  
Arginine Decarboxylase ◽  
Laser Scanning Microscopy ◽  
Polyamine Synthesis ◽  
Content Type ◽  
Wide Range ◽  
Polyamine Content ◽  
Pcc 6803

ABSTRACT The phototropic bacterium Synechocystis sp. strain PCC 6803 is able to adapt its morphology in order to survive in a wide range of harsh environments. Under conditions of high salinity, planktonic cells formed cell aggregates in culture. Further observations using crystal violet staining, confocal laser scanning microscopy, and field emission-scanning electron microscopy confirmed that these aggregates were Synechocystis biofilms. Polyamines have been implicated in playing a role in biofilm formation, and during salt stress the content of spermidine, the major polyamine in Synechocystis , was reduced. Two putative arginine decarboxylases, Adc1 and Adc2, in Synechocystis were heterologously expressed in Escherichia coli and purified. Adc2 had high arginine decarboxylase activity, whereas Adc1 was much less active. Disruption of the adc genes in Synechocystis resulted in decreased spermidine content and formation of biofilms even under nonstress conditions. Based on the characterization of the adc mutants, Adc2 was the major arginine decarboxylase whose activity led to inhibition of biofilm formation, and Adc1 contributed only minimally to the process of polyamine synthesis. Taken together, in Synechocystis the shift from planktonic lifestyle to biofilm formation was correlated with a decrease in intracellular polyamine content, which is the inverse relationship of what was previously reported in heterotroph bacteria. IMPORTANCE There are many reports concerning biofilm formation in heterotrophic bacteria. In contrast, studies on biofilm formation in cyanobacteria are scarce. Here, we report on the induction of biofilm formation by salt stress in the model phototrophic bacterium Synechocystis sp. strain PCC 6803. Two arginine decarboxylases (Adc1 and Adc2) possess function in the polyamine synthesis pathway. Inactivation of the adc1 and adc2 genes leads to biofilm formation even in the absence of salt. The shift from planktonic culture to biofilm formation is regulated by a decrease in spermidine content in Synechocystis . This negative correlation between biofilm formation and polyamine content, which is the opposite of the relationship reported in other bacteria, is important not only in autotrophic but also in heterotrophic bacteria.

Exogenous ABA induces salt tolerance in indica rice (Oryza sativa L.): The role of OsP5CS1 and OsP5CR gene expression during salt stress

2013 ◽  
Vol 86 ◽  
pp. 94-105 ◽  
Author(s):  
Siriporn Sripinyowanich ◽  
Pongsathorn Klomsakul ◽  
Bongkoj Boonburapong ◽  
Thapana Bangyeekhun ◽  
Tadao Asami ◽  
...  
Keyword(s):  
Gene Expression ◽  
Oryza Sativa ◽  
Salt Stress ◽  
Salt Tolerance ◽  
Oryza Sativa L ◽  
Indica Rice ◽  
Exogenous Aba

scholarly journals The versatile interactome of chloroplast ribosomes revealed by affinity purification mass spectrometry

2020 ◽  
Author(s):  
Lisa Désirée Westrich ◽  
Vincent Leon Gotsmann ◽  
Claudia Herkt ◽  
Fabian Ries ◽  
Tanja Kazek ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Environmental Changes ◽  
Affinity Purification ◽  
Small Subunit ◽  
Fine Tuning ◽  
Chloroplast Gene ◽  
Purification Method ◽  
Chloroplast Gene Expression ◽  
Associated Proteins

Abstract In plant cells, chloroplast gene expression is predominantly controlled through post-transcriptional regulation. Such fine-tuning is vital for precisely orchestrating protein complex assembly as for the photosynthesis machinery and for quickly responding to environmental changes. While regulation of chloroplast protein synthesis is of central importance, little is known about the degree and nature of the regulatory network, mainly due to challenges associated with the specific isolation of transient ribosome interactors. Here, we established a ribosome affinity purification method, which enabled us to broadly uncover putative ribosome-associated proteins in chloroplasts. Endogenously tagging of a protein of the large or small subunit revealed not only interactors of the holo complex, but also preferential interactors of the two subunits. This includes known canonical regulatory proteins as well as several new proteins belonging to the categories of protein and RNA regulation, photosystem biogenesis, redox control and metabolism. The sensitivity of the here applied screen was validated for various transiently interacting proteins. We further provided evidence for the existence of a ribosome-associated Nα-acetyltransferase in chloroplasts and its ability to acetylate substrate proteins at their N-terminus. The broad set of ribosome interactors underscores the potential to regulate chloroplast gene expression on the level of protein synthesis.

scholarly journals Till Death Do Us Part—The Multifaceted Role of Platelets in Liver Diseases

2021 ◽  
Vol 22 (6) ◽  
pp. 3113
Author(s):  
Marion Mussbacher ◽  
Laura Brunnthaler ◽  
Anja Panhuber ◽  
Patrick Starlinger ◽  
Alice Assinger
Keyword(s):  
Liver Diseases ◽  
Environmental Changes ◽  
Current Knowledge ◽  
Circulatory System ◽  
Fine Tuning ◽  
Therapeutic Interventions ◽  
Alcoholic Fatty Liver ◽  
Cellular Mediators ◽  
Shed Light

Platelets are tightly connected with the liver, as both their production and their clearance are mediated by the liver. Platelets, in return, participate in a variety of liver diseases, ranging from non-alcoholic fatty liver diseases, (viral) hepatitis, liver fibrosis and hepatocellular carcinoma to liver regeneration. Due to their versatile functions, which include (1) regulation of hemostasis, (2) fine-tuning of immune responses and (3) release of growth factors and cellular mediators, platelets quickly adapt to environmental changes and modulate disease development, leading to different layers of complexity. Depending on the (patho)physiological context, platelets exert both beneficial and detrimental functions. Understanding the precise mechanisms through which platelet function is regulated at different stages of liver diseases and how platelets interact with various resident and non-resident liver cells helps to draw a clear picture of platelet-related therapeutic interventions. Therefore, this review summarizes the current knowledge on platelets in acute and chronic liver diseases and aims to shed light on how the smallest cells in the circulatory system account for changes in the (patho)physiology of the second largest organ in the human body.

scholarly journals The role of epigenetic mechanisms in the regulation of gene expression in the cyclical endometrium

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Alejandra Monserrat Retis-Resendiz ◽  
Ixchel Nayeli González-García ◽  
Moisés León-Juárez ◽  
Ignacio Camacho-Arroyo ◽  
Marco Cerbón ◽  
...  
Keyword(s):  
Gene Expression ◽  
Menstrual Cycle ◽  
Fine Tuning ◽  
Cycle Phase ◽  
Transcriptional Networks ◽  
Epigenetic Mechanisms ◽  
Cell Type ◽  
Expression Of Genes ◽  
Non Coding Rnas

Abstract Background The human endometrium is a highly dynamic tissue whose function is mainly regulated by the ovarian steroid hormones estradiol and progesterone. The serum levels of these and other hormones are associated with three specific phases that compose the endometrial cycle: menstrual, proliferative, and secretory. Throughout this cycle, the endometrium exhibits different transcriptional networks according to the genes expressed in each phase. Epigenetic mechanisms are crucial in the fine-tuning of gene expression to generate such transcriptional networks. The present review aims to provide an overview of current research focused on the epigenetic mechanisms that regulate gene expression in the cyclical endometrium and discuss the technical and clinical perspectives regarding this topic. Main body The main epigenetic mechanisms reported are DNA methylation, histone post-translational modifications, and non-coding RNAs. These epigenetic mechanisms induce the expression of genes associated with transcriptional regulation, endometrial epithelial growth, angiogenesis, and stromal cell proliferation during the proliferative phase. During the secretory phase, epigenetic mechanisms promote the expression of genes associated with hormone response, insulin signaling, decidualization, and embryo implantation. Furthermore, the global content of specific epigenetic modifications and the gene expression of non-coding RNAs and epigenetic modifiers vary according to the menstrual cycle phase. In vitro and cell type-specific studies have demonstrated that epithelial and stromal cells undergo particular epigenetic changes that modulate their transcriptional networks to accomplish their function during decidualization and implantation. Conclusion and perspectives Epigenetic mechanisms are emerging as key players in regulating transcriptional networks associated with key processes and functions of the cyclical endometrium. Further studies using next-generation sequencing and single-cell technology are warranted to explore the role of other epigenetic mechanisms in each cell type that composes the endometrium throughout the menstrual cycle. The application of this knowledge will definitively provide essential information to understand the pathological mechanisms of endometrial diseases, such as endometriosis and endometrial cancer, and to identify potential therapeutic targets and improve women’s health.

scholarly journals Salt Stress Induces non-CG Methylation in Coding Regions of Barley Seedlings (Hordeum vulgare)

2018 ◽  
Author(s):  
Moumouni Konate ◽  
Michael J. Wilkinson ◽  
Benjamin T. Mayne ◽  
Stephen M. Pederson ◽  
Eileen S. Scott ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Salt Stress ◽  
Growth And Yield ◽  
Plant Responses ◽  
Global Methylation ◽  
Repeat Elements ◽  
Close Proximity ◽  
Induced Changes

Salinity can negatively impact crop growth and yield. Changes in DNA methylation are known to occur when plants are challenged by stress and have been associated to the regulation of stress-response genes. However, the role of DNA-methylation in moderating gene expression in response to salt stress has been relatively poorly studied among crops such as barley. Here we assess the extent of salt-induced alterations of DNA methylation in barley, and their putative role in perturbed gene expression. Using Next Generation Sequencing, we screened the leaf and root methylomes of five divergent barley varieties grown under control and three salt concentrations, to seek genotype independent salt-induced changes in DNA methylation. Salt stress caused increased methylation in leaves but diminished methylation in roots with a higher number of changes in leaves than in roots, indicating that salt induced changes to global methylation are tissue specific. DMMs were mostly located in close proximity to repeat elements but also 1094 genes, of which many possessed GO terms associated with plant responses to stress. Identified markers identified have potential value as sentinels of salt stress and provide a start point to understand the functional role of DNA methylation in facilitating barley’s response to this stressor.

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