Search results for " Double-Stranded"

Yeast dsRNA viruses: replication and killer phenotypes

1991

The cytoplasmic L-A dsRNA virus of Saccharomyces cerevisiae consists of a 4.5 kb dsRNA and the two gene products it encodes; the capsid (cap) and at least one copy of the capsid-polymerase (cap-pol) fusion protein. Virion cap-pol catalyses transcription of the plus (sense)-strand; this is extruded from the virus and serves as messenger for synthesis of cap and cap-pol. Nascent cap-pol binds to a specific domain in the plus strand to initiate encapsidation and then catalyses minus-strand synthesis to complete the replication cycle. Products of at least three host genes are required for replication, and virus copy number is kept at tolerable levels by the SKI antivirus system. S. cerevisiae k…

High resistance to X-rays and therapeutic carbon ions in glioblastoma cells bearing dysfunctional ATM associates with intrinsic chromosomal instabili…

2014

To investigate chromosomal instability and radiation response mechanisms in glioblastoma cells.We undertook a comparative analysis of two patient-derived glioblastoma cell lines. Their resistance to low and high linear energy transfer (LET) radiation was assessed using clonogenic survival assay and their intrinsic chromosome instability status using fluorescence in situ hybridization. DNA damage was analyzed by pulsed-field gel electrophoresis and by γ-H2AX foci quantification. Expression of DNA damage response proteins was assessed by immunoblot.Increased radioresistance to X-rays as well as carbon ions was observed in glioblastoma cells exhibiting high levels of naturally occurring chromo…

A member of the Tlr family is involved in dsRNA innate immune response in Paracentrotus lividus sea urchin

2015

Abstract The innate immune response involves proteins such as the membrane receptors of the Toll-like family (TLRs), which trigger different intracellular signalling pathways that are dependent on specific stimulating molecules. In sea urchins, TLR proteins are encoded by members of a large multigenic family composed of 60–250 genes in different species. Here, we report a newly identified mRNA sequence encoding a TLR protein (referred to as Pl-Tlr) isolated from Paracentrotus lividus immune cells. The partial protein sequence contained the conserved Toll/IL-1 receptor (TIR) domain, the transmembrane domain and part of the leucine repeats. Phylogenetic analysis of the Pl-Tlr protein was acco…

Three-dimensional invasion of human glioblastoma cells remains unchanged by X-ray and carbon ion irradiation in vitro.

2012

Purpose Cell invasion represents one of the major determinants that treatment has failed for patients suffering from glioblastoma. Contrary findings have been reported for cell migration upon exposure to ionizing radiation. Here, the migration and invasion capability of glioblastoma cells on and in collagen type I were evaluated upon irradiation with X-rays or carbon ions. Methods and Materials Migration on and invasion in collagen type I were evaluated in four established human glioblastoma cell lines exposed to either X-rays or carbon ions. Furthermore, clonogenic radiation survival, proliferation (5-bromo-2-deoxyuridine positivity), DNA double-strand breaks (γH2AX/53BP1-positive foci), a…

Genotoxic effects of zinc oxide nanoparticles

2015

The potential toxicity of nanoparticles has currently provoked public and scientific discussions, and attempts to develop generally accepted handling procedures for nanoparticles are under way. The investigation of the impact of nanoparticles on human health is overdue and reliable test systems accounting for the special properties of nanomaterials must be developed. Nanoparticular zinc oxide (ZnO) may be internalised through ambient air or the topical application of cosmetics, only to name a few, with unpredictable health effects. Therefore, we analysed the determinants of ZnO nanoparticle (NP) genotoxicity. ZnO NPs (15-18 nm in diameter) were investigated at concentrations of 0.1, 10 and …

Double-stranded RNA polyinosinic-polycytidylic acid immobilized onto gamma-Fe2O3 nanoparticles by using a multifunctional polymeric linker.

2007

Apoptosis in malignant glioma cells triggered by the temozolomide-induced DNA lesion O6-methylguanine

2006

Methylating drugs such as temozolomide (TMZ) are widely used in the treatment of brain tumours (malignant gliomas). The mechanism of TMZ-induced glioma cell death is unknown. Here, we show that malignant glioma cells undergo apoptosis following treatment with the methylating agents N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and TMZ. Cell death determined by colony formation and apoptosis following methylation is greatly stimulated by p53. Transfection experiments with O(6)-methylguanine-DNA methyltransferase (MGMT) and depletion of MGMT by O(6)-benzylguanine showed that, in gliomas, the apoptotic signal originates from O(6)-methylguanine (O(6)MeG) and that repair of O(6)MeG by MGMT prevent…

dsRNA-functionalized multifunctional gamma-Fe2O3 nanocrystals: a tool for targeting cell surface receptors.

2008

Size-dependent knockdown potential of siRNA-loaded cationic nanohydrogel particles.

2014

To overcome the poor pharmacokinetic conditions of short double-stranded RNA molecules in RNA interference therapies, cationic nanohydrogel particles can be considered as alternative safe and stable carriers for oligonucleotide delivery. For understanding key parameters during this process, two different types of well-defined cationic nanohydrogel particles were synthesized, which provided nearly identical physicochemical properties with regards to their material composition and resulting siRNA loading characteristics. Yet, according to the manufacturing process using amphiphilic reactive ester block copolymers of pentafluorophenyl methacrylate (PFPMA) and tri(ethylene glycol)methyl ether m…

Brca2/Xrcc2 dependent HR, but not NHEJ, is required for protection against O6-methylguanine triggered apoptosis, DSBs and chromosomal aberrations by …

2008

Abstract O 6 -methylguanine (O 6 MeG) is a highly critical DNA adduct induced by methylating carcinogens and anticancer drugs such as temozolomide, streptozotocine, procarbazine and dacarbazine. Induction of cell death by O 6 MeG lesions requires mismatch repair (MMR) and cell proliferation and is thought to be dependent on the formation of DNA double-strand breaks (DSBs) or, according to an alternative hypothesis, direct signaling by the MMR complex. Given a role for DSBs in this process, either homologous recombination (HR) or non-homologous end joining (NHEJ) or both might protect against O 6 MeG. Here, we compared the response of cells mutated in HR and NHEJ proteins to temozolomide and…