scholarly journals Two Sp1/Sp3 Binding Sites in the Major Immediate-Early Proximal Enhancer of Human Cytomegalovirus Have a Significant Role in Viral Replication

2005 ◽  
Vol 79 (15) ◽  
pp. 9597-9607 ◽  
Author(s):  
Hiroki Isomura ◽  
Mark F. Stinski ◽  
Ayumi Kudoh ◽  
Tohru Daikoku ◽  
Noriko Shirata ◽  
...  
Keyword(s):  
Viral Replication ◽  
Human Cytomegalovirus ◽  
Significant Role ◽  
Binding Sites ◽  
Human Fibroblast ◽  
Immediate Early ◽  
Fibroblast Cells ◽  
Recombinant Viruses ◽  
Human Fibroblast Cells ◽  
Hcmv Replication

ABSTRACT We previously demonstrated that the major immediate early (MIE) proximal enhancer containing one GC box and the TATA box containing promoter are minimal elements required for transcription and viral replication in human fibroblast cells (H. Isomura, T. Tsurumi, M. F. Stinski, J. Virol. 78:12788-12799, 2004). After infection, the level of Sp1 increased while Sp3 remained constant. Here we report that either Sp1 or Sp3 transcription factors bind to the GC boxes located at approximately positions −55 and −75 relative to the transcription start site (+1). Both the Sp1 and Sp3 binding sites have a positive and synergistic effect on the human cytomegalovirus (HCMV) major immediate-early (MIE) promoter. There was little to no change in MIE transcription or viral replication for recombinant viruses with one or the other Sp1 or Sp3 binding site mutated. In contrast, mutation of both the Sp1 and Sp3 binding sites caused inefficient MIE transcription and viral replication. These data indicate that the Sp1 and Sp3 binding sites have a significant role in HCMV replication in human fibroblast cells.

scholarly journals Role of the Proximal Enhancer of the Major Immediate-Early Promoter in Human Cytomegalovirus Replication

2004 ◽  
Vol 78 (23) ◽  
pp. 12788-12799 ◽  
Author(s):  
Hiroki Isomura ◽  
Tatsuya Tsurumi ◽  
Mark F. Stinski
Keyword(s):  
Virus Replication ◽  
Human Cytomegalovirus ◽  
Human Fibroblast ◽  
Recombinant Virus ◽  
Immediate Early ◽  
Wild Type Virus ◽  
Fibroblast Cells ◽  
Viral Protein Synthesis ◽  
Enhancer Element ◽  
Human Fibroblast Cells

ABSTRACT The human cytomegalovirus (CMV) enhancer has a distal component (positions −550 to −300) and a proximal component (−300 to −39) relative to the transcription start site (+1) of the major immediate-early (MIE) promoter. Without the distal enhancer, human CMV replicates slower and has a small-plaque phenotype. We determined the sequence requirements of the proximal enhancer by making 5′-end deletions to positions −223, −173, −116, −67, and −39. Even though recombinant virus with the proximal enhancer deleted to −39 has the minimal TATA box-containing MIE promoter element, it cannot replicate independently in human fibroblast cells. Recombinant virus with a deletion to −67 has an Sp-1 transcription factor binding site which may represent a minimal enhancer element for recombinant virus replication in human fibroblast cells. Although recombinant virus with a deletion to −223 replicates to titers at least 100-fold less than that of the wild-type virus, it replicates to titers 8-fold higher than that of recombinant virus with a deletion to −173 and 20-fold higher than that of virus with a deletion to −67. Recombinant virus with a deletion to −173 replicates more efficiently than that with a deletion to −116. There was a direct correlation between the level of infectious virus replication and time after infection, amount of MIE gene transcription, MIE and early viral protein synthesis, and viral DNA synthesis. The extent of the proximal enhancer determines the efficiency of viral replication.

scholarly journals Requirement of Multiple cis-Acting Elements in the Human Cytomegalovirus Major Immediate-Early Distal Enhancer for Viral Gene Expression and Replication

2002 ◽  
Vol 76 (1) ◽  
pp. 313-326 ◽  
Author(s):  
Jeffery L. Meier ◽  
Michael J. Keller ◽  
James J. McCoy
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Gene Transcription ◽  
Human Cytomegalovirus ◽  
Viral Gene Expression ◽  
Immediate Early ◽  
Viral Gene ◽  
Distal Enhancer ◽  
Cis Acting ◽  
Hcmv Replication

ABSTRACT We have shown previously that the human cytomegalovirus (HCMV) major immediate-early (MIE) distal enhancer is needed for MIE promoter-dependent transcription and viral replication at low multiplicities of infection (MOI). To understand how this region works, we constructed and analyzed a series of HCMVs with various distal enhancer mutations. We show that the distal enhancer is composed of at least two parts that function independently to coordinately activate MIE promoter-dependent transcription and viral replication. One such part is contained in a 47-bp segment that has consensus binding sites for CREB/ATF, SP1, and YY1. At low MOI, these working parts likely function in cis to directly activate MIE gene expression, thus allowing viral replication to ensue. Three findings support the view that these working parts are likely cis-acting elements. (i) Deletion of either part of a bisegmented distal enhancer only slightly alters MIE gene transcription and viral replication. (ii) Reversing the distal enhancer’s orientation largely preserves MIE gene transcription and viral replication. (iii) Placement of stop codons at −300 or −345 in all reading frames does not impair MIE gene transcription and viral replication. Lastly, we show that these working parts are dispensable at high MOI, partly because of compensatory stimulation of MIE promoter activity and viral replication that is induced by a virion-associated component(s) present at a high viral particle/cell ratio. We conclude that the distal enhancer is a complex multicomponent cis-acting region that is required to augment both MIE promoter-dependent transcription and HCMV replication.

scholarly journals Induction of Chromatin Damage and Distribution of Isochromatid Breaks in Human Fibroblast Cells Exposed to Heavy Ions

2002 ◽  
Vol 43 (S) ◽  
pp. S169-S173 ◽  
Author(s):  
TETSUYA KAWATA ◽  
HISAO ITO ◽  
KEN MOTOORI ◽  
TAKUYA UEDA ◽  
NAOYUKI SHIGEMATSU ◽  
...  
Keyword(s):  
Human Fibroblast ◽  
Heavy Ions ◽  
Fibroblast Cells ◽  
Human Fibroblast Cells

scholarly journals The 5′ Untranslated Region of the Major Immediate Early mRNA Is Necessary for Efficient Human Cytomegalovirus Replication

2018 ◽  
Vol 92 (7) ◽  
Author(s):  
Kyle C. Arend ◽  
Erik M. Lenarcic ◽  
Nathaniel J. Moorman
Keyword(s):  
Protein Expression ◽  
Human Cytomegalovirus ◽  
Untranslated Region ◽  
Mrna Translation ◽  
Lytic Replication ◽  
Immediate Early ◽  
Translation Control ◽  
Positive Role ◽  
Free System ◽  
Hcmv Replication

ABSTRACTThe human cytomegalovirus (HCMV) immediate early 1 (IE1) and IE2 proteins are critical regulators of virus replication. Both proteins are needed to efficiently establish lytic infection, and nascent expression of IE1 and IE2 is critical for reactivation from latency. The regulation of IE1 and IE2 protein expression is thus a central event in the outcome of HCMV infection. Transcription of the primary transcript encoding both IE1 and IE2 is well studied, but relatively little is known about the posttranscriptional mechanisms that control IE1 and IE2 protein synthesis. The mRNA 5′ untranslated region (5′ UTR) plays an important role in regulating mRNA translation. Therefore, to better understand the control of IE1 and IE2 mRNA translation, we examined the role of the shared 5′ UTR of the IE1 and IE2 mRNAs (MIE 5′ UTR) in regulating translation. In a cell-free system, the MIE 5′ UTR repressed translation, as predicted based on its length and sequence composition. However, in transfected cells we found that the MIE 5′ UTR increased the expression of a reporter gene and enhanced its association with polysomes, demonstrating that the MIE 5′ UTR has a positive role in translation control. We also found that the MIE 5′ UTR was necessary for efficient IE1 and IE2 translation during infection. Replacing the MIE 5′ UTR with an unstructured sequence of the same length decreased IE1 and IE2 protein expression despite similar levels of IE1 and IE2 mRNA and reduced the association of the IE1 and IE2 mRNAs with polysomes. The wild-type MIE 5′-UTR sequence was also necessary for efficient HCMV replication. Together these data identify the shared 5′ UTR of the IE1 and IE2 mRNAs as an important regulator of HCMV lytic replication.IMPORTANCEThe HCMV IE1 and IE2 proteins are critical regulators of HCMV replication, both during primary infection and during reactivation from viral latency. Thus, defining factors that regulate IE1 and IE2 expression is important for understanding the molecular events controlling the HCMV replicative cycle. Here we identify a positive role for the MIE 5′ UTR in mediating the efficient translation of the IE1 and IE2 mRNAs. This result is an important advance for several reasons. To date, most studies of IE1 and IE2 regulation have focused on defining events that regulate IE1 and IE2 transcription. Our work reveals that in addition to the regulation of transcription, IE1 and IE2 are also regulated at the level of translation. Therefore, this study is important in that it identifies an additional layer of regulation controlling IE1 and IE2 expression and thus HCMV pathogenesis. These translational regulatory events could potentially be targeted by novel antiviral therapeutics that limit IE1 and IE2 mRNA translation and thus inhibit lytic replication or prevent HCMV reactivation.

O-083 Non-invasive, label-free optical analysis to detect aneuploidy within the inner cell mass of the preimplantation embryo

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
C Y Tan ◽  
S B Mahbub ◽  
C A Campugan ◽  
J Campbell ◽  
A Habibalahi ◽  
...  
Keyword(s):  
Hyperspectral Imaging ◽  
Human Fibroblast ◽  
Preimplantation Embryo ◽  
Mouse Embryos ◽  
Treated Mouse ◽  
Fibroblast Cells ◽  
Label Free ◽  
Primary Human Fibroblast ◽  
Non Invasive ◽  
Human Fibroblast Cells

Abstract Study question Can we separate between control and reversine-treated cells within the inner cell mass (ICM) of the mouse preimplantation embryo by using label-free and non-invasive hyperspectral microscopy? Summary answer Hyperspectral microscopy is able to discern between control and reversine-treated cells using cellular autofluorescence in the complete absence of fluorescence tags. What is known already Embryo mosaicism (containing cells that are euploid (46 chromosomes) and aneuploid (deviation from the expected number of chromosomes)) affects up to 17.3% of human blastocyst embryos. Current diagnosis of aneuploidy in the IVF clinic involves a biopsy of trophectoderm (TE) cells or spent media followed by sequencing. In some blastocyst embryos these approaches will fail to diagnose of the proportion of aneuploid cells within the fetal lineage (ICM). Study design, size, duration The impact of aneuploidy on cellular metabolism was assessed by using cellular autofluoresence and hyperspectral microscopy (broad spectral profile). Two models were employed: (i) Primary human fibroblast cells with known karyotypes (4-6 independent replicates, euploid n = 467; aneuploid n = 969) and reversine induced aneuploidy in mouse embryos (5-8 independent replicates, 30-44 cells per group). Both models were subjected to hyperspectral imaging to quantify native cell fluorescence. Participants/materials, setting, methods The human model is comprised of euploid (male and female) and aneuploid (triploid and trisomies: 13, 18, 21, XXX, and XXY) primary human fibroblast cells. For the mouse model, we treated embryos with reversine, a reversible spindle assembly checkpoint inhibitor, during the 4- to 8-cell division. Individual blastomeres were dissociated from control and reversine treated 8-cell embryos. Blastomeres were either imaged directly or used to generate chimeric blastocysts with differing ratios of control:reversine-treated cells. Main results and the role of chance Following unsupervised linear unmixing, the relative abundance of metabolic cofactors was quantified: reduced nicotinamide adenine dinucleotide (NAD(P)H) and flavins with the subsequent calculation of the optical redox ratio (ORR: Flavins/[NAD(P)H + Flavins]). Primary human fibroblast cells displayed an increase in the relative abundance of NAD(P)H with a decrease in flavins, leading to a significant reduction in the ORR for aneuploid cells (P < 0.05). The mouse embryos displayed an identical trend as the human model between control and reversine-treated embryos. Mathematical algorithms were applied and able to distinguish between (i) euploid and aneuploid primary human fibroblast cells, (ii) control and reversine-treated mouse blastomeres and (iii) chimeric blastocysts with differing ratios of control and reversine-treated cells. The accuracy of these separations was supported by receiver operating characteristic curves with areas under the curve. We also showed that hyperspectral imaging of the preimplantation embryo does not impact on embryo developmental competence, pregnancy outcome and offspring health in a mouse model. We believe the role of chance is low as both human somatic cells and mouse embryos showed a consistent shift in cellular metabolism in response to human fibroblast cells that are aneuploid and reversine treated mouse embryos. Limitations, reasons for caution Further validation of our approach could include sequencing of the ICM of individual blastocysts to determine the proportion of aneuploid cells in ICM and correlate this with the metabolic profile obtained through hyperspectral imaging. Wider implications of the findings With hyperspectral imaging able to discriminate between (i) euploid and aneuploid human fibroblast cells and (ii) control and reversine-treated mouse embryos, this could be an accurate, non-invasive and label-free optical imaging approach to assess mosaicism within the ICM of mouse embryos, potentially leading to a new diagnostic tool for embryos. Trial registration number Not applicable

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