Recombinant Components Research Articles

PAK4 Inhibition Impacts Growth and Survival, and Increases Sensitivity to DNA-Damaging Agents in Waldestrostom Macroglobulinemia

p21-activated kinases (PAKs) are effectors for the small GTPases Cdc42 and Rac that control a wide range of cellular processes including cytoskeleton reorganization, cell proliferation, survival and motility. Based on our initial results showing significant biological and functional role of PAK4 in plasma cell malignancies, we investigated its role in Waldenström macroglobulinemia (WM). We first confirmed high level of PAK4 expression and activity in WM cells. Both genetic depletion via stable lentiviral knock down and pharmacological inhibition of PAK4 via allosteric modulator KPT-9274 decreased tumor cell growth and survival in a dose and time dependent manner in a panel of WM cell lines. The growth inhibitory effect was associated with induction of apoptotic cell death, caspases activation and PARP cleavage as well as modulation of pro-apoptotic proteins such as PUMA. In addition, related-PAK4 biological processes such as migration, invasion and adhesion to bone marrow stromal cells (BMSCs) were significantly impacted by the inhibitor. A significant effect of KPT9274 was also observed in primary tumor cells from both newly diagnosed and relapse WM patients, including primary cells from ibrutinib resistant patients.To gain further insight into the consequences of PAK4 inhibition, we performed gene expression profile in WM cell lines treated with KPT-9274. Intriguingly we detected a significant impact on expression of Fanconi Anemia (FA)/BRCA pathway related genes, a DNA-damage response pathway essential for the repair of DNA interstrand crosslinks (ICLs) and regulation of cellular responses to replication stress. Since FA/BRCA deficient cells are defective in the formation of Rad51 foci, a crucial component of the homologous recombination (HR) repair machinery, we examined the effect of PAK4/NAMPT inhibition on Rad51 as well its impact on HR. We observed that, apart from inducing DNA damage, assessed by γH2AX expression, KPT-9274 specifically inhibited Rad51 and the double strand break repair by the homologous recombination pathway. Protein pull down analysis revealed the existence of a complex between nicotinamide phosphoribosyltransferase (NAMPT) and the conserved PAK binding domain; treatment with KPT-9274 disrupted this interaction and inhibited the enzymatic activity of NAMPT. NAD is necessary for PARP function especially with increasing DNA damage; and its depletion severely hamper DNA repair. Consistent with this, we observed that nicotinic acid supplementation rescued the effect of KPT-9274 on NAMPT inhibition as well as DNA damage and repair.As FA/BRCA pathway has been shown to affects sensitivity to alkylating agents, we next combined KPT-9274 with either melphalan or bendamustine in MM and WM cells. The combination treatment resulted in a synergistic time- and dose-dependent inhibition of cell survival and growth in cell lines and primary patient tumor cells. We observed a synergistic induction of apoptosis and activation of caspase-3/7, -8 and -9 following treatment with combined versus single-agent therapy. Similarly, in PAK4 knock-down WM cells bendamustine significantly increased the rate of early and late apoptotic cells (60%) compared to scrambled knockdown cells (37%).In summary, we report a significant anti-proliferative activity of dual PAK4-NAMPT inhibition in WM cells, with induction of apoptosis, DNA-damage response and FA/BRCA pathway disruption and a strong synergistic activity in combination with DNA damaging agents such as Bendamustine. Altogether, our data suggests dual PAK4-NAMPT inhibition represents a novel therapeutic strategies in WM. DisclosuresSenapedis:Karyopharm Therapeutics Inc: Employment, Equity Ownership. Baloglu:Karyopharm Therapeutics Inc: Employment, Equity Ownership. Oliva:Takeda: Honoraria; Celgene: Honoraria. Anderson:Oncopep: Other: scientific founder; C4 Therapeutics: Other: scientific founder; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees; Millenium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; MedImmune: Membership on an entity's Board of Directors or advisory committees. Treon:Pharmacyclics: Consultancy, Research Funding.

Molecular characterization of faba bean necrotic yellows viruses in Tunisia.

Faba bean necrotic yellows virus (FBNYV) (genus Nanovirus; family Nanoviridae) has a genome comprising eight individually encapsidated circular single-stranded DNA components. It has frequently been found infecting faba bean (Vicia faba L.) and chickpea (Cicer arietinum L.) in association with satellite molecules (alphasatellites). Genome sequences of FBNYV from Azerbaijan, Egypt, Iran, Morocco, Spain and Syria have been determined previously and we now report the first five genome sequences of FBNYV and associated alphasatellites from faba bean sampled in Tunisia. In addition, we have determined the genome sequences of two additional FBNYV isolates from chickpea plants sampled in Syria and Iran. All individual FBNYV genome component sequences that were determined here share>84% nucleotide sequence identity with FBNYV sequences available in public databases, with the DNA-M component displaying the highest degree of diversity. As with other studied nanoviruses, recombination and genome component reassortment occurs frequently both between FBNYV genomes and between genomes of nanoviruses belonging to other species.

High efficiency screen-printed n-type silicon solar cell using co-diffusion of APCVD boron emitter and POCl3 back surface field

We present the fabrication and analysis of Passivated Emitter and Rear Totally Diffused (PERT) solar cells on n-type silicon using a co-diffusion process. In a single high temperature step, a BSG/SiOx stack deposited by APCVD and a POCl3 back surface field diffuse into the wafer to form the boron doped emitter and phosphorus doped back surface field. The SiOx layer on top of BSG acts as a masking layer to prevent cross-doping of phosphorus as well as a blocking layer for boron out-diffusion. This resulted in an initial sheet resistance of 76 Ω/□ with good uniformity and a final p+ emitter sheet resistance of 97 Ω/□ after boron rich layer removal. Additionally, bulk lifetime was investigated before and after the high temperature step that resulted in an increase from 1.2 ms to 1.5 ms due to a POCl3 gettering effect. A peak cell efficiency of 20.3% was achieved and each recombination component in terms of saturation current density was calculated and analyzed to understand the cell for further efficiency enhancement.

An improved multi-kernel RVM integrated with CEEMD for high-quality intervals prediction construction and its intelligent modeling application

Most of existing modeling methods are based on point prediction. However, the accuracy of point prediction cannot meet the actual demand due to existence of high noise, volatility, complexity and irregularity inherent in the chemical process data. In order to solve this problem, a hybrid high-quality prediction intervals (PIs) method integrating complementary ensemble empirical mode decomposition (CEEMD), sample entropy (SE), and improved multi-kernel relevant vector machine (RVM) is proposed in the paper. The proposed PIs method mainly consists of three aspects: Firstly, CEEMD is adopted to decompose the original data into several independent intrinsic mode functions (IMFS), and then SE is used to analyze the complexity of the extracted IMFs to obtain recombinant components; Secondly, an improved multi-kernel RVM (MRVM) is presented to predict recombinant components independently, in which the linear kernel and the Gaussian kernel are combined; Thirdly, the predicted components are aggregated to obtain an ensemble result using another MRVM for constructing the high-quality PIs. To verify the performance of the proposed PIs method, a purified Terephthalic acid (PTA) solvent system is selected. Comparative simulation results demonstrate that the proposed PIs method greatly outperforms on coverage probability and sharpness in all the step predictions.

Genomic features shaping the landscape of meiotic double-strand-break hotspots in maize

Meiotic recombination is the most important source of genetic variation in higher eukaryotes. It is initiated by formation of double-strand breaks (DSBs) in chromosomal DNA in early meiotic prophase. The DSBs are subsequently repaired, resulting in crossovers (COs) and noncrossovers (NCOs). Recombination events are not distributed evenly along chromosomes but cluster at recombination hotspots. How specific sites become hotspots is poorly understood. Studies in yeast and mammals linked initiation of meiotic recombination to active chromatin features present upstream from genes, such as absence of nucleosomes and presence of trimethylation of lysine 4 in histone H3 (H3K4me3). Core recombination components are conserved among eukaryotes, but it is unclear whether this conservation results in universal characteristics of recombination landscapes shared by a wide range of species. To address this question, we mapped meiotic DSBs in maize, a higher eukaryote with a large genome that is rich in repetitive DNA. We found DSBs in maize to be frequent in all chromosome regions, including sites lacking COs, such as centromeres and pericentromeric regions. Furthermore, most DSBs are formed in repetitive DNA, predominantly Gypsy retrotransposons, and only one-quarter of DSB hotspots are near genes. Genic and nongenic hotspots differ in several characteristics, and only genic DSBs contribute to crossover formation. Maize hotspots overlap regions of low nucleosome occupancy but show only limited association with H3K4me3 sites. Overall, maize DSB hotspots exhibit distribution patterns and characteristics not reported previously in other species. Understanding recombination patterns in maize will shed light on mechanisms affecting dynamics of the plant genome.

Thiopurine-induced mitotic catastrophe in Rad51d-deficient mammalian cells.

Thiopurines are part of a clinical regimen used for the treatment of autoimmune disorders and childhood acute lymphoblastic leukemia. However, despite these successes, there are also unintended consequences such as therapy-induced cancer in long-term survivors. Therefore, a better understanding of cellular responses to thiopurines will lead to improved and personalized treatment strategies. RAD51D is an important component of homologous recombination (HR), and our previous work established that mammalian cells defective for RAD51D are more sensitive to the thiopurine 6-thioguanine (6TG) and have dramatically increased numbers of multinucleated cells and chromosome instability. 6TG is capable of being incorporated into telomeres, and interestingly, RAD51D contributes to telomere maintenance, although the precise function of RAD51D at the telomeres remains unclear. We sought here to investigate: (1) the activity of RAD51D at telomeres, (2) the contribution of RAD51D to protect against 6TG-induced telomere damage, and (3) the fates of Rad51d-deficient cells following 6TG treatment. These results demonstrate that RAD51D is required for maintaining the telomeric 3' overhangs. As measured by γ-H2AX induction and foci formation, 6TG induced DNA damage in Rad51d-proficient and Rad51d-deficient cells. However, the extent of γ-H2AX telomere localization following 6TG treatment was higher in Rad51d-deficient cells than in Rad51d-proficient cells. Using live-cell imaging of 6TG-treated Rad51d-deficient cells, two predominant forms of mitotic catastrophe were found to contribute to the formation of multinucleated cells, failed division and restitution. Collectively, these findings provide a unique window into the role of the RAD51D HR protein during thiopurine induction of mitotic catastrophe. Environ. Mol. Mutagen. 59:38-48, 2018. © 2017 Wiley Periodicals, Inc.

Evidence for Complex Formation of the Bacillus cereus Haemolysin BL Components in Solution.

Haemolysin BL is an important virulence factor regarding the diarrheal type of food poisoning caused by Bacillus cereus. However, the pathogenic importance of this three-component enterotoxin is difficult to access, as nearly all natural B. cereus culture supernatants additionally contain the highly cytotoxic Nhe, the second three-component toxin involved in the aetiology of B. cereus-induced food-borne diseases. To better address the toxic properties of the Hbl complex, a system for overexpression and purification of functional, cytotoxic, recombinant (r)Hbl components L2, L1 and B from E. coli was established and an nheABC deletion mutant was constructed from B. cereus reference strain F837/76. Furthermore, 35 hybridoma cell lines producing monoclonal antibodies (mAbs) against Hbl L2, L1 and B were generated. While mAbs 1H9 and 1D8 neutralized Hbl toxicity and thus, represent important tools for future investigations of the mode-of-action of Hbl on the target cell surface, mAb 1D7, in contrast, even enhanced Hbl toxicity by supporting the binding of Hbl B to the cell surface. By using the specific mAbs in Dot blots, indirect and hybrid sandwich enzyme immuno assays (EIAs), complex formation between Hbl L1 and B, as well as L1 and L2 in solution could be shown for the first time. Surface plasmon resonance experiments with the rHbl components confirmed these results with KD values of 4.7 × 10−7 M and 1.5 × 10−7 M, respectively. These findings together with the newly created tools lay the foundation for the detailed elucidation of the molecular mode-of-action of the highly complex three-component Hbl toxin.

80 Value of specific IgE detection against the recombinant antigenic components of Aspergillus fumigatus in the diagnosis of allergic bronchopulmonary aspergillosis in adult patients with cystic fibrosis

80 Value of specific IgE detection against the recombinant antigenic components of Aspergillus fumigatus in the diagnosis of allergic bronchopulmonary aspergillosis in adult patients with cystic fibrosis

Multistep Photoluminescence Decay Reveals Dissociation of Geminate Charge Pairs in Organolead Trihalide Perovskites

Charge carrier dynamics in organolead iodide perovskites is analyzed by employing time‐resolved photoluminescence spectroscopy with several ps time resolution. The measurements performed by varying photoexcitation intensity over five orders of magnitude enable separation of photoluminescence components related to geminate and nongeminate charge carrier recombination and to address the dynamics of an isolated geminate electron–hole pair. Geminate recombination dominates at low excitation fluence and determines the initial photoluminescence decay. This decay component is remarkably independent of the material structure and experimental conditions. It is demonstrated that dependences of the geminate and nongeminate radiative recombination components on excitation intensity, repetition rate, and temperature, are hardly compatible with carrier trapping and exciton dissociation models. On the basis of semiclassical and quantum mechanical numerical calculation results, it is argued that the fast photoluminescence decay originates from gradual spatial separation of photogenerated weakly bound geminate charge pairs.

The chromatin-remodeling subunit Baf200 promotes homology-directed DNA repair and regulates distinct chromatin-remodeling complexes

The efficiency and type of pathway chosen to repair DNA double-strand breaks (DSBs) are critically influenced by the nucleosome packaging and the chromatin architecture surrounding the DSBs. The Swi/Snf (PBAF and BAF) chromatin-remodeling complexes contribute to DNA damage-induced nucleosome remodeling, but the mechanism by which it contributes to this function is poorly understood. Herein, we report how the Baf200 (Arid2) PBAF-defining subunit regulates DSB repair. We used cytological and biochemical approaches to show that Baf200 plays an important function by facilitating homologous recombination-dependent processes, such as recruitment of Rad51 (a key component of homologous recombination) to DSBs, homology-directed repair, and cell survival after DNA damage. Furthermore, we observed that Baf200 and Rad51 are present in the same complex and that this interaction is mediated by C-terminal sequences in both proteins. It has been recognized previously that the interplay between distinct forms of Swi/Snf has profound functional consequences, but we understand little about the composition of complexes formed by PBAF protein subunits. Our biochemical analyses reveal that Baf200 forms at least two distinct complexes. One is a canonical form of PBAF including the Swi/Snf-associated Brg1 catalytic subunit, and the other contains Baf180 but not Brg1. This distinction of PBAF complexes based on their unique composition provides the foundation for future studies on the specific contributions of the PBAF forms to the regulation of DNA repair.

Immune modulation by dendritic-cell-based cancer vaccines.

The interplay between host immunity and tumour cells has opened the possibility of targeting tumour cells by modulation of the human immune system. Cancer immunotherapy involves the treatment of a tumour by utilizing the recombinant human immune system components to target the pro-tumour microenvironment or by revitalizing the immune system with the ability to kill tumour cells by priming the immune cells with tumour antigens. In this review, current immunotherapy approaches to cancer with special focus on dendritic cell (DC)-based cancer vaccines are discussed. Some of the DC-based vaccines under clinical trials for various cancer types are highlighted. Establishing tumour immunity involves a plethora of immune components and pathways; hence, combining chemotherapy, radiation therapy and various arms of immunotherapy, after analysing the benefits of individual therapeutic agents, might be beneficial to the patient.

Evolution of meiotic recombination genes in maize and teosinte

BackgroundMeiotic recombination is a major source of genetic variation in eukaryotes. The role of recombination in evolution is recognized but little is known about how evolutionary forces affect the recombination pathway itself. Although the recombination pathway is fundamentally conserved across different species, genetic variation in recombination components and outcomes has been observed. Theoretical predictions and empirical studies suggest that changes in the recombination pathway are likely to provide adaptive abilities to populations experiencing directional or strong selection pressures, such as those occurring during species domestication. We hypothesized that adaptive changes in recombination may be associated with adaptive evolution patterns of genes involved in meiotic recombination.ResultsTo examine how maize evolution and domestication affected meiotic recombination genes, we studied patterns of sequence polymorphism and divergence in eleven genes controlling key steps in the meiotic recombination pathway in a diverse set of maize inbred lines and several accessions of teosinte, the wild ancestor of maize. We discovered that, even though the recombination genes generally exhibited high sequence conservation expected in a pathway controlling a key cellular process, they showed substantial levels and diverse patterns of sequence polymorphism. Among others, we found differences in sequence polymorphism patterns between tropical and temperate maize germplasms. Several recombination genes displayed patterns of polymorphism indicative of adaptive evolution.ConclusionsDespite their ancient origin and overall sequence conservation, meiotic recombination genes can exhibit extensive and complex patterns of molecular evolution. Changes in these genes could affect the functioning of the recombination pathway, and may have contributed to the successful domestication of maize and its expansion to new cultivation areas.

Abstract PR09: c-MYC preserves genomic integrity during DNA replication: a paradigm shift of c-MYC

Abstract During DNA synthesis, single-stranded DNA breaks (SSBs) are easily produced by mitogenic and oxidative stresses. Although SSBs are naturally converted to double-stranded DNA breaks (DSBs) at the collapse of replication forks, the integrity of chromosomal DNA is regularly maintained during DNA synthesis. Because DNA replication is a fundamental biological process involved in homeostasis, we hypothesized that an S-phase-associated guardian of the genome constantly stimulates cellular DSB repair machinery during DNA replication. The p53 tumor suppressor is known to act as the guardian of the genome. However, in response to DSBs, p53 not only activates G1 arrest, but also represses RAD51, a key component of homologous recombination (HR), an error-free DSB repair mechanism. Moreover, p53 is regularly dormant in actively growing cells. Thus, p53 cannot be the S-phase-associated DNA-repair enhancer. In this study, we show that the c-MYC transcription factor, which promotes DNA replication, concomitantly stimulates ataxia telangiectasia mutated kinase (ATM), γH2AX formation, and DSB repair by repressing BIN1. As an E2F1 corepressor, BIN1 suppressed the human ATM promoter, whereas via protein-protein interaction, BIN1 negatively regulated ATM auto-phosphorylation at serine 1981, a critical step for ATM activation. Accordingly, even before DSBs were formed, impaired BIN1 was sufficient to enhance ATM-dependent phosphorylation of histone H2AX at serine 139 (forming γH2AX), which has been widely used as a biomarker of DSBs. Reduced BIN1-dependent γH2AX foci formation was accompanied by the phosphorylation of MDC1 (mediator of DNA damage checkpoint protein 1) and 53BP1 foci. Furthermore, loss of BIN1 substantially accelerated cellular DSB-repair activity, which was reversed by the depletion of BRCA2, a critical player of HR. Intriguingly, activated c-MYC recruited the chromatin-remodeling factor BRG1 to and transcriptionally repressed the BIN1 promoter, thus indirectly liberating ATM expression. Because c-MYC robustly increases γH2AX foci, the oncoprotein has been thought to induce real DSBs. However, c-MYC silencing did not diminish γH2AX foci in the absence of BIN1, suggesting that c-MYC-induced γH2AX foci formation is chiefly attributable to c-MYC-induced decrease in BIN1 and following ATM reactivation in a manner independent of DSBs. Our study identifies c-MYC-associated γH2AX as a novel warning beacon of imminent DSBs and establishes a new paradigm for c-MYC in facilitating DSB-repair signaling during DNA replication. This abstract is also being presented as Poster B20. Citation Format: Alpana Kumari, Tetsushi Iwasaki, Walson P. Folk, Amy L. Abdulovic-Cui, Slovénie Pyndiah, George C. Prendergast, John M. Sedivy, Daitoku Sakamuro. c-MYC preserves genomic integrity during DNA replication: a paradigm shift of c-MYC. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Cancer Cell Cycle - Tumor Progression and Therapeutic Response; Feb 28-Mar 2, 2016; Orlando, FL. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(11_Suppl):Abstract nr PR09.

Performance enhancement of blue light-emitting diodes with InGaN/GaN multi-quantum wells grown on Si substrates by inserting thin AlGaN interlayers

We have grown blue light-emitting diodes (LEDs) having InGaN/GaN multi-quantum wells (MQWs) with thin AlyGa1−yN (0 < y < 0.3) interlayers on Si(111) substrates. It was found by high-resolution transmission electron microscopy observations and three-dimensional atom probe analysis that 1-nm-thick interlayers with an AlN mole fraction of less than y = 0.3 were continuously formed between GaN barriers and InGaN wells, and that the AlN mole fraction up to y = 0.15 could be consistently controlled. The external quantum efficiency of the blue LED was enhanced in the low-current-density region (≤45 A/cm2) but reduced in the high-current-density region by the insertion of the thin Al0.15Ga0.85N interlayers in the MQWs. We also found that reductions in both forward voltage and wavelength shift with current were achieved by inserting the interlayers even though the inserted AlGaN layers had potential higher than that of the GaN barriers. The obtained peak wall-plug efficiency was 83% at room temperature. We suggest that the enhanced electroluminescence (EL) performance was caused by the introduction of polarization-induced hole carriers in the InGaN wells on the side adjacent to the thin AlGaN/InGaN interface and efficient electron carrier transport through multiple wells. This model is supported by temperature-dependent EL properties and band-diagram simulations. We also found that inserting the interlayers brought about a reduction in the Shockley-Read-Hall nonradiative recombination component, corresponding to the shrinkage of V-defects. This is another conceivable reason for the observed performance enhancement.

Utility of Specific IgE to Ara h 2 in Italian Allergic and Tolerant Children Sensitized to Peanut.

Emerging data suggest that measurement of serum IgE to peanut components can be clinically helpful and more accurate than IgE to whole peanut to predict peanut allergy. Not all studies have used prospective samples, multiple components and oral challenges. Currently, there are no data on this topic involving Italian children. 32 patients (23 males; median age 9 years) with reported history for peanut allergy and evidence of peanut sensitization (skin prick test to peanut extract ≥ 3mm) have been analyzed for serum IgE to whole peanut and recombinant allergen components Ara h 1, 2, 3, 8, and 9 with Immuno CAP and completed an open oral food challenge with peanut. 12 (37.5%) children had a positive challenge to peanut and were considered allergic. No differences were seen between the median values of IgE to peanut, Ara h 1, 3, 8 and 9 in allergic and tolerant children to peanut challenge. Noteworthy, 5 of 20 tolerant children had IgE to peanut> 15 kUA/l which is commonly considered a predictive value of peanut allergy. Conversely, a significant difference was seen when comparing the median value of IgE to Ara h 2 in the two groups: 0.75 kUA/l (IQR: 0.22-4.34 kUA/l) in allergic children versus 0.1 kUA/l (IQR: 0.1-0.12 kUA/l) in tolerant ones (P< 0.001). IgE levels to Ara h 2 are significantly higher in children that react to oral peanut challenge. Our findings in Italian children have been in line with recent reports in various populations of Northern Europe, the US and Australia and add confirmatory evidence that analysis of IgE to Ara h 2 could reduce the need for peanut challenge in suspected allergic patients.

Mycobacteriophage putative GTPase-activating protein can potentiate antibiotics.

The soaring incidences of infection by antimicrobial resistant (AR) pathogens and shortage of effective antibiotics with new mechanisms of action have renewed interest in phage therapy. This scenario is exemplified by resistant tuberculosis (TB), caused by resistant Mycobacterium tuberculosis. Mycobacteriophage SWU1 A321_gp67 encodes a putative GTPase-activating protein. Mycobacterium smegmatis with gp67 overexpression showed changed colony formation and biofilm morphology and supports the efficacy of streptomycin and capreomycin against Mycobacterium. gp67 down-regulated the transcription of genes involved in cell wall and biofilm development. To our knowledge, this is the first report to show that phage protein in addition to lysin or recombination components can synergize with existing antibiotics. Phage components might represent a promising new clue for better antibiotic potentiators.

Environmental Stress Induces Trinucleotide Repeat Mutagenesis in Human Cells by Alt-Nonhomologous End Joining Repair

Multiple pathways modulate the dynamic mutability of trinucleotide repeats (TNRs), which are implicated in neurodegenerative disease and evolution. Recently, we reported that environmental stresses induce TNR mutagenesis via stress responses and rereplication, with more than 50% of mutants carrying deletions or insertions—molecular signatures of DNA double-strand break repair. We now show that knockdown of alt-nonhomologous end joining (alt-NHEJ) components—XRCC1, LIG3, and PARP1—suppresses stress-induced TNR mutagenesis, in contrast to the components of homologous recombination and NHEJ, which have no effect. Thus, alt-NHEJ, which contributes to genetic mutability in cancer cells, also plays a novel role in environmental stress-induced TNR mutagenesis.

Achievements, Investigations in Gynecologic Oncology Explored

Achievements, Investigations in Gynecologic Oncology Explored

The role of schematic support in age-related associative deficits in short-term and long-term memory

Abstract Older, relative to younger adults, exhibit an associative memory deficit in short-term and long-term memory, characterized by difficulty in binding distinct components to form associations, while item memory remains largely intact. Reduced performance emerges mostly due to high false alarm rates in older adults’ associative memory. One factor that could increase older adult false alarm rates during associative recognition memory tests is a decreased use of recollection processes that allow the rejection of recombined components from the study phase. The current experiments assessed the degree to which an increase in the use of semantic memory (schematic) support, by changing the patterns of support from study to test, can help older adults reduce their associative false alarms using recollection. In two experiments, face–name pairs were presented to younger and older adults. During a continuous recognition task assessing memory performance at short-term and long-term memory retention intervals, younger and older adults were tested on individual faces, names, and face–name pairs that either remained intact or were recombined within the same (e.g., old-face, old-name) or between two different age categories (e.g., old-face, young-name). In Experiment 2, we also collected “remember–know” judgments after responses to recognition test events. In both experiments, the results indicated benefits to older adults’ associative memory when changes in schematic support occurred from study to test at long-term but not short-term memory retention intervals. The results of Experiment 2 indicate that these increases in performance were mediated by the availability of recollection processes during retrieval.

Rad51 Regulates Reprogramming Efficiency through DNA Repair Pathway.

Rad51 is a key component of homologous recombination (HR) to repair DNA double-strand breaks and it forms Rad51 recombinase filaments of broken single-stranded DNA to promote HR. In addition to its role in DNA repair and cell cycle progression, Rad51 contributes to the reprogramming process during the generation of induced pluripotent stem cells. In light of this, we performed reprogramming experiments to examine the effect of co-expression of Rad51 and four reprogramming factors, Oct4, Sox2, Klf4, and c-Myc, on the reprogramming efficiency. Co-expression of Rad51 significantly increased the numbers of alkaline phosphatase-positive colonies and embryonic stem cell-like colonies during the process of reprogramming. Co-expression ofRad51 significantly increased the expression of epithelial markers at an early stage of reprogramming compared with control cells. Phosphorylated histone H2AX (γH2AX), which initiates the DNA double-strand break repair system, was highly accumulated in reprogramming intermediates upon co-expression of Rad51. This study identified a novel role of Rad51 in enhancing the reprogramming efficiency, possibly by facilitating mesenchymal-to-epithelial transition and by regulating a DNA damage repair pathway during the early phase of the reprogramming process.