scholarly journals Increased Induction of Osteopetrosis, but Unaltered Lymphomagenicity, by Murine Leukemia Virus SL3-3 after Mutation of a Nuclear Factor 1 Site in the Enhancer

1999 ◽  
Vol 73 (12) ◽  
pp. 10406-10415 ◽  
Author(s):  
Steen Ethelberg ◽  
Barbara D. Tzschaschel ◽  
Arne Luz ◽  
Salvador J. Diaz-Cano ◽  
Finn Skou Pedersen ◽  
...  

ABSTRACT SL3-3 is a murine leukemia virus which is only weakly bone pathogenic but highly T-cell lymphomagenic. A major pathogenic determinant is the transcriptional enhancer comprising several transcription factor binding sites, among which are three identical sites for nuclear factor 1 (NF1). We have investigated the pathogenic properties of NF1 site enhancer mutants of SL3-3. Two different mutants carrying a 3-bp mutation either in all three NF1 sites or in the central site alone were constructed and assayed in inbred NMRI mice. The wild type and both mutants induced lymphomas in all mice, with a mean latency period of 9 weeks. However, there was a considerable difference in osteopetrosis induction. Wild-type SL3-3 induced osteopetrosis in 11% of the mice (2 of 19), and the triple NF1 site mutant induced osteopetrosis in none of the mice (0 of 19), whereas the single NF1 site mutant induced osteopetrosis in 56% (10 of 18) of the mice, as determined by X-ray analysis. A detailed histological examination of the femurs of the mice was carried out and found to support this diagnosis. Thus, the NF1 sites of SL3-3 are major determinants of osteopetrosis induction, without determining lymphomagenesis. This conclusion was further supported by evaluation of the bone pathogenicity of other SL3-3 enhancer variants, the lymphomagenicity of which had been examined previously. This evaluation furthermore strongly indicated that the core sites, a second group of transcription factor binding sites in the viral enhancer, are necessary for the osteopetrosis induction potential of SL3-3.

Neurosurgery ◽  
2011 ◽  
Vol 68 (6) ◽  
pp. 1667-1676 ◽  
Author(s):  
Mitja I. Kurki ◽  
Sanna-Kaisa Häkkinen ◽  
Juhana Frösen ◽  
Riikka Tulamo ◽  
Mikael von und zu Fraunberg ◽  
...  

Abstract BACKGROUND: Aneurysmal subarachnoid hemorrhage, almost always from saccular intracranial aneurysm (sIA), is a devastating form of stroke that affects the working-age population. Cellular and molecular mechanisms predisposing to the rupture of the sIA wall are largely unknown. This knowledge would facilitate the design of novel diagnostic tools and therapies for the sIA disease. OBJECTIVE: To investigate gene expression patterns distinguishing ruptured and unruptured sIA. METHODS: We compared the whole-genome expression profile of 11 ruptured sIA wall samples with that of 8 unruptured ones using oligonucleotide microarrays. Signaling pathways enriched in the ruptured sIA walls were identified with bioinformatic analyses. Their transcriptional control was predicted in silico by seeking the enrichment of conserved transcription factor binding sites in the promoter regions of differentially expressed genes. RESULTS: Overall, 686 genes were significantly upregulated and 740 were downregulated in the ruptured sIA walls. Significantly upregulated biological processes included response to turbulent blood flow, chemotaxis, leukocyte migration, oxidative stress, vascular remodeling; and extracellular matrix degradation. Toll-like receptor signaling and nuclear factor-κB, hypoxia-inducible factor-1A, and ETS transcription factor binding sites were significantly enriched among the upregulated genes. CONCLUSION: We identified pathways and candidate genes associated with the rupture of human sIA wall. Our results may provide clues to the molecular mechanism in sIA wall rupture and insight for novel therapeutic strategies to prevent rupture.


2010 ◽  
Vol 84 (15) ◽  
pp. 7473-7483 ◽  
Author(s):  
James W. Bruce ◽  
Michael Hierl ◽  
John A. T. Young ◽  
Paul Ahlquist

ABSTRACT To identify cellular processes involved in retroviral infection, we employed a high-volume forward genetic screen of insertionally mutagenized somatic cells using a murine leukemia virus (MLV) vector. This approach identified a clonal cell line that exhibited approximately 10-fold reduced gene expression from MLV vectors following infection despite supporting normal levels of MLV reverse transcription and integration. The defect in this cell line was specific for the MLV long terminal repeat (LTR) promoter, as normal levels of reporter gene expression were obtained from both an internal cytomegalovirus (CMV) promoter contained within an LTR-defective MLV vector and LTR expression from an avian sarcoma and leukosis virus (ASLV) vector. Complementation and shRNA knockdown experiments demonstrated that the defective gene in these cells is ZASC1 (ZNF639), a transcription factor with strong links to cancer and inherited ataxias. We demonstrated that ZASC1 is a sequence-specific DNA binding protein with three closely related binding sites located within the MLV LTR promoter, but it does not bind to the ASLV promoter. Mutating these putative ZASC1 binding sites significantly reduced levels of MLV gene expression. While wild-type ZASC1 activated expression from the MLV promoter, a green fluorescent protein-ZASC1 fusion protein showed dominant-negative inhibition of MLV gene expression. These studies identify the cellular transcription factor ZASC1 as an activator of MLV gene expression and provide tools that should be useful in studying the links between ZASC1 and human diseases.


Virology ◽  
2005 ◽  
Vol 334 (2) ◽  
pp. 234-244 ◽  
Author(s):  
Karina Dalsgaard Sørensen ◽  
Annette Balle Sørensen ◽  
Leticia Quintanilla-Martinez ◽  
Sandra Kunder ◽  
Jörg Schmidt ◽  
...  

2019 ◽  
Author(s):  
Danielle Denisko ◽  
Coby Viner ◽  
Michael M. Hoffman

AbstractChromatin immunoprecipitation-sequencing (ChIP-seq) is widely used to find transcription factor binding sites, but suffers from various sources of noise. Knocking out the target factor mitigates noise by acting as a negative control. Paired wild-type and knockout experiments can generate improved motifs but require optimal differential analysis. We introduce peaKO—a method to automatically optimize motif analyses with knockout controls, which we compare to two other methods. PeaKO often improves elucidation of the target factor and highlights the benefits of knockout controls, which far outperform input controls. It is freely available at https://peako.hoffmanlab.org.


Sign in / Sign up

Export Citation Format

Share Document