scholarly journals Role of the Distal sarA Promoters in SarA Expression in Staphylococcus aureus

2005 ◽  
Vol 73 (7) ◽  
pp. 4391-4394 ◽  
Author(s):  
Ambrose L. Cheung ◽  
Adhar C. Manna
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Protein Level ◽  
Target Gene ◽  
Open Reading Frame ◽  
Reading Frame ◽  
Regulatory Locus ◽  
Target Gene Expression

ABSTRACT The global regulatory locus sarA comprises a 375-bp open reading frame that is driven by three promoters, the proximal P1 and distal P3 and P2 promoters. We mutated the weaker P3 and P2 promoters to ascertain the effect of the change on SarA protein and target gene expression. Our results indicated that the solely active P1 promoter led to a lower SarA protein level, which has an effect on agr transcription and subsequently had corresponding effects on hla, sspA, and spa transcription, probably in both agr-independent and agr-dependent manners.

scholarly journals The Immediate-Early Gene Product Encoded by Open Reading Frame 57 of Herpesvirus Saimiri Modulates Gene Expression at a Posttranscriptional Level

1998 ◽  
Vol 72 (1) ◽  
pp. 857-861 ◽  
Author(s):  
Adrian Whitehouse ◽  
Matthew Cooper ◽  
David M. Meredith
Keyword(s):  
Gene Expression ◽  
Gene Product ◽  
Target Gene ◽  
Immediate Early Gene ◽  
Open Reading Frame ◽  
Early Gene ◽  
Immediate Early ◽  
Herpesvirus Saimiri ◽  
Amino Acid Homology ◽  
Reading Frame

ABSTRACT The herpesvirus saimiri (HVS) immediate-early gene product encoded by open reading frame (ORF) 57 shares limited amino acid homology with HSV-1 ICP27 and Epstein-Barr virus BMLF1, both regulatory proteins. The ORF 57 gene has been proposed to be spliced based on the genome sequence, and here we confirm the intron-exon structure of the gene. We also demonstrate that a cDNA construct of the ORF 57 gene product represses the transactivating capability of the ORF 50a gene product (which is produced from a spliced transcript), but activates that of ORF 50b (an unspliced transcript). Further analyses with cotransfection experiments show that ORF 57 can either activate or repress expression from a range of both early and late HVS promoters, depending on the target gene. These results indicate that repression of gene expression mediated by the ORF 57 gene product is dependent on the presence of an intron within the target gene encoding region. Furthermore, Northern blot analysis demonstrates that the levels of mRNA transcribed from genes not containing an intron are not significantly affected in the presence of the ORF 57 gene product. This suggests that it regulates gene expression through a posttranscriptional mechanism.

Controlled atmospheres and sugar can delay malate synthase gene expression during asparagus senescence

2002 ◽  
Vol 29 (9) ◽  
pp. 1045 ◽  
Author(s):  
Simon A. Coupe ◽  
Ben K. Sinclair ◽  
Sheryl D. Somerfield ◽  
Paul L. Hurst
Keyword(s):  
Gene Expression ◽  
Single Gene ◽  
Malate Synthase ◽  
Open Reading Frame ◽  
Asparagus Officinalis ◽  
High Identity ◽  
Reading Frame ◽  
Controlled Atmospheres ◽  
Foliar Senescence

A cDNA clone encoding malate synthase (MS; EC 4.1.3.2) was isolated from a 48-h postharvest asparagus (Asparagus officinalis L.) spear cDNA library using a MS clone from Brassica napus. The asparagus MS (AoMS1) cDNA hybridized to a 1.9-kb transcript that increased in abundance preferentially in spear-tip tissue during postharvest storage. The AoMS1 transcript also accumulated during natural foliar senescence of asparagus fern. The cDNA consists of 1960 nucleotides with an open reading frame of 1665 nucleotides or 555 amino acids, and encodes a deduced protein with a predicted Mr of 63 kDa and a pI of 8.1. The deduced amino acid sequence of AoMS1 showed high identity with the B. napus MS clone (77.2%) used to isolate it, and with MS from cucumber (77%). Genomic Southern analysis suggests that a single gene in asparagus encodes AoMS1. Controlled- atmosphere treatments aimed at reducing deterioration of harvested asparagus spears reduced the expression of AoMS1. The reduction was correlated with the reduced oxygen level, and reduced MS enzyme activity was also observed. Asparagus cell cultures were used to test the role of sugar status in regulating AoMS1 gene expression. In cultures without sucrose there was an accumulation of AoMS1 transcript that was absent in cultures containing sucrose.

scholarly journals CDK6 kinase activity is required for thymocyte development

Blood ◽  
2011 ◽  
Vol 117 (23) ◽  
pp. 6120-6131 ◽  
Author(s):  
Miaofen G. Hu ◽  
Amit Deshpande ◽  
Nicolette Schlichting ◽  
Elisabeth A. Hinds ◽  
Changchuin Mao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Target Gene ◽  
Kinase Activity ◽  
Thymocyte Development ◽  
Hematopoietic Stem ◽  
Notch Target Gene ◽  
Target Gene Expression ◽  
Lymphoid Malignancies ◽  
Proliferation And Differentiation

Abstract Cyclin-dependent kinase-6 (CDK6) is required for early thymocyte development and tumorigenesis. To mechanistically dissect the role of CDK6 in thymocyte development, we generated and analyzed mutant knock-in mice and found that mice expressing a kinase-dead Cdk6 allele (Cdk6K43M) had a pronounced reduction in thymocytes and hematopoietic stem cells and progenitor cells (Lin−Sca-1+c-Kit+ [LSK]). In contrast, mice expressing the INK4-insensitive, hyperactive Cdk6R31C allele displayed excess proliferation in LSK and thymocytes. However, this is countered at least in part by increased apoptosis, which may limit progenitor and thymocyte expansion in the absence of other genetic events. Our mechanistic studies demonstrate that CDK6 kinase activity contributes to Notch signaling because inactive CDK6 kinase disrupts Notch-dependent survival, proliferation, and differentiation of LSK, with concomitant alteration of Notch target gene expression, such as massive up-regulation of CD25. Further, knockout of CD25 in Cdk6K43M mice rescued most defects observed in young mice. These results illustrate an important role for CDK6 kinase activity in thymocyte development that operates partially through modulating Notch target gene expression. This role of CDK6 as a downstream mediator of Notch identifies CDK6 kinase activity as a potential therapeutic target in human lymphoid malignancies.

scholarly journals Hepatocyte Nuclear Factor 4 alpha (HNF4α) Activation is Essential for Termination of Liver Regeneration

2018 ◽  
Author(s):  
Ian Huck ◽  
Sumedha Gunewardena ◽  
Regina Espanol-Suner ◽  
Holger Willenbring ◽  
Udayan Apte
Keyword(s):  
Gene Expression ◽  
Liver Regeneration ◽  
Target Gene ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Hepatic Differentiation ◽  
Target Gene Expression ◽  
Protein Levels ◽  
Hepatocyte Nuclear Factor 4

AbstractHepatocyte Nuclear Factor 4 alpha (HNF4α) is critical for hepatic differentiation. Recent studies have highlighted its role in inhibition of hepatocyte proliferation and tumor suppression. However, the role of HNF4α in liver regeneration is not known. We hypothesized that hepatocytes modulate HNF4α activity when navigating between differentiated and proliferative states during liver regeneration. Western blot analysis revealed a rapid decline in nuclear and cytoplasmic HNF4α protein levels accompanied with decreased target gene expression within 1 hour after 2/3 partial hepatectomy (post-PH) in C57BL/6J mice. HNF4α protein expression did not recover to the pre-PH levels until day 3. Hepatocyte-specific deletion of HNF4α (HNF4α-KO) in mice resulted in 100% mortality post-PH despite increased proliferative marker expression throughout regeneration. Sustained loss of HNF4α target gene expression throughout regeneration indicated HNF4α-KO mice were unable to compensate for loss of HNF4α transcriptional activity. Deletion of HNF4α resulted in sustained proliferation accompanied by c-myc and cyclin D1 over expression and a complete deficiency of hepatocyte function after PH. Interestingly, overexpression of degradation-resistant HNF4α in hepatocytes did not prevent initiation of regeneration after PH. Finally, AAV8-mediated reexpression of HNF4α in hepatocytes of HNF4α-KO mice post-PH restored HNF4α protein levels, induced target gene expression and improved survival of HNF4α-KO mice post-PH. In conclusion, these data indicate that HNF4α reexpression following initial decrease is critical for hepatocytes to exit from cell cycle and resume function during the termination phase of liver regeneration. These results reveal the role of HNF4α in liver regeneration and have implications for therapy of liver failure.

Abstract 13: Development of Functionalized Nanoparticle Platform for Reducing Atherosclerosis

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Shobha Ghosh ◽  
Jing Wang ◽  
Jinghua Bie ◽  
Quan Yuan ◽  
Olga Zolotarskaya ◽  
...  
Keyword(s):  
Gene Expression ◽  
Animal Studies ◽  
Target Gene ◽  
Foam Cells ◽  
Expression Vectors ◽  
Transgenic Expression ◽  
Target Gene Expression ◽  
Macrophage Foam Cells ◽  
Plaque Regression

No therapy is currently available to enhance the removal of cholesteryl esters (CE) from existing atherosclerotic plaques to facilitate plaque regression. Such a strategy is crucial to reduce the burden of existing disease in addition to preventing the progression targeted by the current therapeutics. Earlier studies from our laboratory have established the anti-atherogenic role of CE hydrolase (CEH)-mediated CE mobilization from macrophage foam cells and final elimination of cholesterol by the liver. While transgenic expression of CEH was used in pre-clinical animal studies, increase in human CEH by activation of Liver-X-receptor (LXR) was also established. Increased lipogenesis induced by LXR ligands precludes their use. The current studies focused on the development of mannose-functionalized dendrimer nanoparticles (DNPs) for the delivery of LXR ligand (TO901317) or CEH expression vector to plaque associated macrophage foam cells. As shown in the Figure, mannose functionalization restricts the uptake of DNPs to macrophages and minimal uptake was seen with primary hepatocytes ( A ). Western diet fed LDLR-/- mice were injected (iv) with DNPs and tissues harvested 48 later to monitor gene expression by QPCR. DNP-mediated delivery of LXR ligand (DNP-LXR) increased the target gene expression (ABCA1, ABCG1) in plaque associated macrophage foam cells in the aortic arch with no effects on target gene expression in the liver ( B ) demonstrating the specific delivery of LXR ligand. Comparable increase in CEH activity was seen following exposure of macrophages to free LXR ligand and DNP-delivered LXR ligand ( C ) and DNP-mediated delivery of CEH expression vectors driven either by CMV or SR-A promoter induced dramatic increase in CEH expression ( D ). These data establish functionalized DNP as a suitable platform for specific and functional delivery of drugs or DNA to plaque associated macrophages to enhance processes involved in cholesterol removal and plaque regression.

scholarly journals The Herpesvirus Saimiri Open Reading Frame 73 Gene Product Interacts with the Cellular Protein p32

2002 ◽  
Vol 76 (22) ◽  
pp. 11612-11622 ◽  
Author(s):  
Kersten T. Hall ◽  
Mathew S. Giles ◽  
Michael A. Calderwood ◽  
Delyth J. Goodwin ◽  
David A. Matthews ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Product ◽  
Cellular Protein ◽  
Open Reading Frame ◽  
Nuclear Accumulation ◽  
Herpesvirus Saimiri ◽  
Human Carcinoma ◽  
Reading Frame ◽  
Amino Terminal

ABSTRACT The role of the gamma-2 herpesvirus open reading frame (ORF) 73 gene product has become the focus of considerable interest. It has recently been shown that the Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) is expressed during a latent infection and can modulate both viral and cellular gene expression. The herpesvirus saimiri (HVS) ORF 73 gene product has some sequence homology to LANA; however, the role of HVS ORF 73 is unknown. We have previously demonstrated that HVS ORF73 is expressed in a stably transduced human carcinoma cell line, where HVS genomes persist as nonintegrated circular episomes. This implies that there may be some functional homology between these proteins. To further investigate the role of the HVS ORF 73 protein, the yeast two-hybrid system was employed to identify interacting cellular proteins. We demonstrate that ORF 73 interacts with the cellular protein p32 and triggers the accumulation of p32 in the nucleus. Using reporter gene-based transient-transfection assays, we demonstrate that ORF 73 can transactivate a number of heterologous promoter constructs and also upregulate its own promoter. Moreover, ORF 73 and p32 act synergistically to transactivate these promoters. The binding of ORF 73 to p32 is mediated by an amino-terminal arginine-rich domain, which contains two functionally distinct nuclear localization signals. The p32 binding domains are required for ORF 73 transactivating abilities and for ORF 73 to induce nuclear accumulation of p32. These results suggest that ORF 73 can function as a regulator of gene expression and that p32 is involved in ORF 73-dependent transcriptional activation.

scholarly journals MiR-124 synergism with ELAVL3 enhances target gene expression to promote neuronal maturity

2020 ◽  
Author(s):  
Ya-Lin Lu ◽  
Yangjian Liu ◽  
Matthew J. McCoy ◽  
Andrew S. Yoo
Keyword(s):  
Gene Expression ◽  
Mirna Target ◽  
Target Gene ◽  
Target Genes ◽  
Dependent Manner ◽  
Neuronal Function ◽  
Mirna Target Gene ◽  
Target Gene Expression ◽  
Human Neurons

SummaryNeuron-enriched microRNAs (miRNAs), miR-9/9* and miR-124 (miR-9/9*-124), direct cell fate switching of human fibroblasts to neurons when ectopically expressed by repressing anti-neurogenic genes. How these miRNAs function after the onset of the transcriptome switch to a neuronal fate remains unclear. Here, we identified direct targets of miRNAs by Argonaute (AGO) HITS-CLIP as reprogramming cells activate the neuronal program and reveal the role of miR-124 that directly promotes the expression of its target genes associated with neuronal development and function. The mode of miR-124 as a positive regulator is determined by a neuron-enriched RNA-binding protein, ELAVL3, that interacts with AGO and binds target transcripts, whereas the non-neuronal ELAVL1 counterpart fails to elevate the miRNA-target gene expression. Although existing literature indicate that miRNA-ELAVL1 interaction can result in either target gene upregulation or downregulation in a context-dependent manner, we specifically identified neuronal ELAVL3 as the driver for miRNA target gene upregulation in neurons. In primary human neurons, repressing miR-124 and ELAVL3 led to the downregulation of genes involved in neuronal function and process outgrowth, and cellular phenotypes of reduced inward currents and neurite outgrowth. Results from our study support the role of miR-124 promoting neuronal function through positive regulation of its target genes.

scholarly journals SarA of Staphylococcus aureus Binds to the sarA Promoter To Regulate Gene Expression

2008 ◽  
Vol 190 (6) ◽  
pp. 2239-2243 ◽  
Author(s):  
Ambrose L. Cheung ◽  
Koren Nishina ◽  
Adhar C. Manna
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Dnase I ◽  
Open Reading Frame ◽  
Regulate Gene Expression ◽  
Reading Frame ◽  
Dnase I Footprinting ◽  
Gel Shift ◽  
Regulate Gene

ABSTRACT The 375-bp sarA open reading frame is driven by three promoters, P1, P3, and P2. Using gel shift and DNase I footprinting assays, we found that SarA binds to two 26-bp sequences and one 31-bp sequence within the P1 and P3 promoters, respectively. Together with the results of transcription analyses, our data indicate that SarA binds to its own promoter to down-regulate sarA expression.

scholarly journals Characterization of a sar Homolog ofStaphylococcus epidermidis

1998 ◽  
Vol 66 (6) ◽  
pp. 2871-2878 ◽  
Author(s):  
Ursula Fluckiger ◽  
Christiane Wolz ◽  
Ambrose L. Cheung
Keyword(s):  
Staphylococcus Aureus ◽  
Target Gene ◽  
Regulatory Element ◽  
Open Reading Frame ◽  
Virulence Determinants ◽  
Coagulase Negative Staphylococci ◽  
Major Open Reading Frame ◽  
Reading Frame ◽  
Major Interest

ABSTRACT Coagulase-negative staphylococci are common nosocomial pathogens. A regulatory element, designated sar, partially controls exoprotein synthesis in coagulase-positive Staphylococcus aureus by modulating the expression of another regulatory locus, called agr. We report here the cloning of a sarhomolog in S. epidermidis. The major open reading frame within sar in S. epidermidis is highly homologous (84%) to the S. aureus SarA protein. Primer extension studies revealed three sar transcripts (0.64, 0.76, and 0.85 kb) initiated from three distinct promoters. The interpromoter region in S. epidermidis differs from itsS. aureus counterpart, possibly suggesting target gene differences and a disparate pattern for sar activation. Remarkably, the S. epidermidis sar homolog interacts with an agr promoter fragment of S. aureus in gel shift assays. Additionally, S. epidermidis sar fragments could restore hemolysin production in an S. aureus sarmutant. As typical virulence determinants controlled by sarin S. aureus are not present in S. epidermidis, an examination of functional and structural similarities and divergence of sar in staphylococci will be of major interest.

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