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1.
Sci Rep ; 14(1): 23445, 2024 Oct 08.
Artículo en Inglés | MEDLINE | ID: mdl-39379431

RESUMEN

The work report on architecture of integrated frequency selective meta-surface (IFSMS) absorbers for aerospace stealth applications. Fabricated IFSMS comprised of a pattern metasurface integrated with dielectric interlayer and conducting ground. Initially, a supercell (2 × 2-unit cell: 24 × 24 mm2) was designed with a fourfold topological symmetry. Supercell produces impedances (R), inductances (L), and capacitances (C) in tune with design on its interaction with microwave. RC performance was tested at variable incident transverse electric/magnetic (TE/TM) modes over, Θ, 0°-60° and at the normal incidence (TE), against a planer, clockwise rotation over, Φ, 0°-90°. The mode stability and rotational invariance was analyzed for displacement current- and power-density distributions. The impedance behavior and phase reversal S11 reflection coefficient studies revealed the emergence of mid-band Fabry-Perot mode distinguishing LC behavior of the circuit. The meta-pattern was manufactured by mask lithography using a customized resistive micro-carbon ink and imprinted onto dielectric/ground tile (dimension: 30 × 30 cm2). Structure-property relationship of the ink material was investigated using SEM, XRD, FTIR, UV-visible spectroscopy to reveled surface properties of imprinted material. The absorber was subjected to the free space measurements over C (4-8), X (8-12), and Ku (12-18 GHz) bands, including pristine interlayer dielectrics. The simulated and experimental RC data was found to be in excellent agreement. The proposed IFSMS design is a potential candidate for the stealth application.

2.
Immunohematology ; 40(3): 122-127, 2024 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-39373303

RESUMEN

Hemolytic disease of the fetus and newborn (HDFN) due to an antibody in the Kell blood group system can be associated with severe fetal anemia. This case report details the challenges of managing a Kellnull mother with anti-Ku that affected her fetus/newborn. A gravida 4 para 3 woman at term underwent an emergency lower caesarean section because of fetal distress. The baby was intubated because of low oxygen saturation. An urgent request for a hematology workup showed severe anemia and erythroblastosis fetalis. Unfortunately, no compatible blood was found, and the baby died. The case was referred to the National Blood Centre, and anti-Ku was confirmed in a sample sent from the mother. When she presented with her fifth pregnancy, meticulous planning was used to manage this pregnancy. Her family screening revealed one brother with a matching phenotype. Three blood donations were planned for the brother-for freezing, for intrauterine transfusion, and for standby during delivery. Serial anti-Ku titrations of maternal samples were performed, and the fetus was monitored for anemia through middle cerebral artery Doppler scans. Although the anti-Ku titers reached as high as 1024, fetal anemia was never diagnosed. The neonate was delivered safely but was diagnosed with severe pathologic jaundice and anemia secondary to HDFN and congenital pneumonia. The baby was transfused with K0 packed red blood cells and later discharged to home.


Asunto(s)
Eritroblastosis Fetal , Sistema del Grupo Sanguíneo de Kell , Humanos , Femenino , Embarazo , Eritroblastosis Fetal/inmunología , Eritroblastosis Fetal/sangre , Sistema del Grupo Sanguíneo de Kell/inmunología , Sistema del Grupo Sanguíneo de Kell/genética , Recién Nacido , Adulto , Isoanticuerpos/sangre , Isoanticuerpos/inmunología , Resultado Fatal , Masculino
3.
Biotechnol Lett ; 2024 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-39235648

RESUMEN

Rotifers are small, ubiquitous invertebrate animals found throughout the world and have emerged as a promising model system for studying molecular mechanisms in the fields of experimental ecology, aquatic toxicology, and geroscience. However, the lack of efficient gene expression manipulation techniques has hindered the study of rotifers. In this study, we used the L4440 plasmid with two reverse-oriented T7 promoters, along with RNase-deficient E. coli HT115, to efficiently produce dsRNA and thereby present an efficient feeding-based RNAi method in Brachionus plicatilis. We targeted Bp-Ku70 & Ku80, key proteins in the DNA double-strand breaks repair pathway, and then subjected rotifers to UV radiation. We found that the mRNA expression, fecundity, as well as survival rate diminished significantly as a result of RNAi. Overall, our results demonstrate that the feeding-based RNAi method is a simple and efficient tool for gene knockdown in B. plicatilis, advancing their use as a model organism for biological research.

4.
J Neurosurg ; : 1-9, 2024 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-39332035

RESUMEN

OBJECTIVE: The lateral spread response (LSR) is an important electrophysiological sign that predicts successful decompression in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS). However, LSRs do not consistently correlate with clinical outcomes, and there are cases in which LSRs are absent. In this study, the authors identified a unique pattern on facial nerve electromyography (EMG) when the root exit zone (REZ) is touched. This distinctive EMG pattern, which the authors coined the "Sang-ku sign" (SKS), could aid in identifying the offending vessel on the REZ, even in the absence of LSRs. METHODS: Between November 2022 and August 2023, the authors analyzed EMG findings from 185 patients undergoing MVD for HFS. Bipolar stimulation electrodes were placed at the marginal mandibular branch, and recordings were obtained from the frontalis and orbicularis oris muscles. Additionally, stimulation electrodes were placed at the temporal branch, and recordings were obtained from the oris and mentalis muscles. The authors statistically analyzed the presence of SKS and its association with demographic, surgical, clinical outcomes, and anatomical factors. RESULTS: The authors observed a brief, burst-like wave pattern arising from all recorded muscle branches when Teflon felt was placed between the REZ and the facial nerve. This EMG pattern, the SKS, was found in 164 patients (88.6%). Among the factors analyzed, only patient age showed a significant association with the presence of the SKS in univariate analysis (p = 0.007). The presence of the SKS was significantly associated with predicting the disappearance of LSRs (p = 0.045). Clinical outcomes were favorable (99% at the last follow-up) in all cases; thus, no positive correlation was observed in the existence of the SKS and LSRs. CONCLUSIONS: The SKS could serve as an excellent guide for the facial nerve REZ during surgery. Given that HFS results from abnormal vascular contact on the REZ, this finding plays a crucial role in ensuring surgical success. Alongside LSRs, the SKS could provide valuable insights for neurosurgeons.

5.
Proc Natl Acad Sci U S A ; 121(37): e2403038121, 2024 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-39226359

RESUMEN

Proteostasis and genomic integrity are respectively regulated by the endoplasmic reticulum-associated protein degradation (ERAD) and DNA damage repair signaling pathways, with both pathways essential for carcinogenesis and drug resistance. How these signaling pathways coordinate with each other remains unexplored. We found that ER stress specifically induces the DNA-PKcs-regulated nonhomologous end joining (NHEJ) pathway to amend DNA damage and impede cell death. Intriguingly, sustained ER stress rapidly decreased the activity of DNA-PKcs and DNA damage accumulated, facilitating a switch from adaptation to cell death. This DNA-PKcs inactivation was caused by increased KU70/KU80 protein degradation. Unexpectedly, the ERAD ligase HRD1 was found to efficiently destabilize the classic nuclear protein HDAC1 in the cytoplasm, by catalyzing HDAC1's polyubiquitination at lysine 74, at a late stage of ER stress. By abolishing HDAC1-mediated KU70/KU80 deacetylation, HRD1 transmits ER signals to the nucleus. The resulting enhanced KU70/KU80 acetylation provides binding sites for the nuclear E3 ligase TRIM25, resulting in the promotion of polyubiquitination and the degradation of KU70/KU80 proteins. Both in vitro and in vivo cancer models showed that genetic or pharmacological inhibition of HADC1 or DNA-PKcs sensitizes colon cancer cells to ER stress inducers, including the Food and Drug Administration-approved drug celecoxib. The antitumor effects of the combined approach were also observed in patient-derived xenograft models. These findings identify a mechanistic link between ER stress (ERAD) in the cytoplasm and DNA damage (NHEJ) pathways in the nucleus, indicating that combined anticancer strategies may be developed that induce severe ER stress while simultaneously inhibiting KU70/KU80/DNA-PKcs-mediated NHEJ signaling.


Asunto(s)
Daño del ADN , Proteína Quinasa Activada por ADN , Estrés del Retículo Endoplásmico , Ubiquitina-Proteína Ligasas , Animales , Humanos , Ratones , Línea Celular Tumoral , Reparación del ADN por Unión de Extremidades , Reparación del ADN , Proteína Quinasa Activada por ADN/metabolismo , Proteína Quinasa Activada por ADN/genética , Retículo Endoplásmico/metabolismo , Histona Desacetilasa 1/metabolismo , Histona Desacetilasa 1/genética , Autoantígeno Ku/metabolismo , Autoantígeno Ku/genética , Proteolisis , Transducción de Señal , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitinación
6.
Front Cell Dev Biol ; 12: 1394531, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39228401

RESUMEN

DNA-protein crosslinks pose a significant challenge to genome stability and cell viability. Efficient repair of DPCs is crucial for preserving genomic integrity and preventing the accumulation of DNA damage. Despite recent advances in our understanding of DPC repair, many aspects of this process, especially at the organismal level, remain elusive. In this study, we used zebrafish as a model organism to investigate the role of TDP2 (Tyrosyl-DNA phosphodiesterase 2) in DPC repair. We characterized the two tdp2 orthologs in zebrafish using phylogenetic, syntenic and expression analysis and investigated the phenotypic consequences of tdp2 silencing in zebrafish embryos. We then quantified the effects of tdp2a and tdp2b silencing on cellular DPC levels and DSB accumulation in zebrafish embryos. Our findings revealed that tdp2b is the main ortholog during embryonic development, while both orthologs are ubiquitously present in adult tissues. Notably, the tdp2b ortholog is phylogenetically closer to human TDP2. Silencing of tdp2b, but not tdp2a, resulted in the loss of Tdp2 activity in zebrafish embryos, accompanied by the accumulation of DPCs and DSBs. Our findings contribute to a more comprehensive understanding of DPC repair at the organismal level and underscore the significance of TDP2 in maintaining genome stability.

7.
J Interpers Violence ; 39(17-18): 3983-4012, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39119654

RESUMEN

In response to the data revolution, academic research and media attention have increasingly focused on the technological adaptation and innovation displayed by the far right. The greatest attention is paid to social media and how groups and organizations are utilizing technological advancement and growth in virtual networks to increase recruitment and advance radicalization on a global scale. As with most social and political endeavors, certain technologies are in vogue and thus draw the attention of users and regulators and service providers. This creates a technological blind spot within which extremist groups frequently operate older and less well regarded technologies without the oversight that one might expect. This article examines the less well-studied traditional and official websites of the Ku Klux Klan, the most established and iconic of American far-right organizations. By incorporating non-participant observation of online spaces and thematic analysis, this research analyzes the evolution of 26 websites, from their emergence in the early 1990s to the present day. We examine the ways in which traditional printed communications and other ephemera have progressed with advances in technology, focusing on the following central elements of Klan political activism and community formation: Klan identity, organizational history, aims and objectives; technology and outreach, including online merchandise and event organization; and the constructions of whiteness and racism. The results add value and insight to comparable work by offering a unique historical insight into the ways in which the Klan have developed and made use of Web 1.0, Web 2.0, and Web3 technologies.


Asunto(s)
Internet , Humanos , Medios de Comunicación Sociales , Activismo Político , Estados Unidos , Historia del Siglo XX
8.
FEMS Yeast Res ; 242024 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-39179418

RESUMEN

Komagataella phaffii (Pichia pastoris) is a methylotrophic yeast that is favored by industry and academia mainly for expression of heterologous proteins. However, its full potential as a host for bioproduction of valuable compounds cannot be fully exploited as genetic tools are lagging behind those that are available for baker's yeast. The emergence of CRISPR-Cas9 technology has significantly improved the efficiency of gene manipulations of K. phaffii, but improvements in gene-editing methods are desirable to further accelerate engineering of this yeast. In this study, we have developed a versatile vector-based CRISPR-Cas9 method and showed that it works efficiently at different genetic loci using linear DNA fragments with very short targeting sequences including single-stranded oligonucleotides. Notably, we performed site-specific point mutations and full gene deletions using short (90 nt) single-stranded oligonucleotides at very high efficiencies. Lastly, we present a strategy for transient inactivation of nonhomologous end-joining (NHEJ) pathway, where KU70 gene is disrupted by a visual marker (uidA gene). This system enables precise CRISPR-Cas9-based editing (including multiplexing) and facilitates simple reversion to NHEJ-proficient genotype. In conclusion, the tools presented in this study can be applied for easy and efficient engineering of K. phaffii strains and are compatible with high-throughput automated workflows.


Asunto(s)
Sistemas CRISPR-Cas , Saccharomycetales , Saccharomycetales/genética , Oligonucleótidos/genética , Ingeniería Genética/métodos , Eliminación de Gen , Vectores Genéticos/genética , Reparación del ADN por Unión de Extremidades , Edición Génica/métodos
9.
AMB Express ; 14(1): 96, 2024 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-39215862

RESUMEN

Trichophyton rubrum is one of the most frequently isolated fungi in patients with dermatophytosis. Despite its clinical significance, the molecular mechanisms of drug resistance and pathogenicity of T. rubrum remain to be elucidated because of the lack of genetic tools, such as efficient gene targeting systems. In this study, we generated a T. rubrum strain that lacks the nonhomologous end-joining-related gene ku80 (Δku80) and then developed a highly efficient genetic recombination system with gene targeting efficiency that was 46 times higher than that using the wild-type strain. Cyp51A and Cyp51B are 14-α-lanosterol demethylase isozymes in T. rubrum that promote ergosterol biosynthesis and are the targets of azole antifungal drugs. The expression of cyp51A mRNA was induced by the addition of the azole antifungal drug efinaconazole, whereas no such induction was detected for cyp51B, suggesting that Cyp51A functions as an azole-responsive Cyp51 isozyme. To explore the contribution of Cyp51A to susceptibility to azole drugs, the neomycin phosphotransferase (nptII) gene cassette was inserted into the cyp51A 3'-untranslated region of Δku80 to destabilize the mRNA of cyp51A. In this mutant, the induction of cyp51A mRNA expression by efinaconazole was diminished. The minimum inhibitory concentration for several azole drugs of this strain was reduced, suggesting that dermatophyte Cyp51A contributes to the tolerance for azole drugs. These findings suggest that an efficient gene targeting system using Δku80 in T. rubrum is applicable for analyzing genes encoding drug targets.

10.
Cell Rep ; 43(8): 114538, 2024 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-39058590

RESUMEN

Repair of DNA double-strand breaks by the non-homologous end-joining pathway is initiated by the binding of Ku to DNA ends. Multiple Ku proteins load onto linear DNAs in vitro. However, in cells, Ku loading is limited to ∼1-2 molecules per DNA end. The mechanisms enforcing this limit are currently unclear. Here, we show that the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs), but not its protein kinase activity, is required to prevent excessive Ku entry into chromatin. Ku accumulation is further restricted by two mechanisms: a neddylation/FBXL12-dependent process that actively removes loaded Ku molecules throughout the cell cycle and a CtIP/ATM-dependent mechanism that operates in S phase. Finally, we demonstrate that the misregulation of Ku loading leads to impaired transcription in the vicinity of DNA ends. Together, our data shed light on the multiple mechanisms operating to prevent Ku from invading chromatin and interfering with other DNA transactions.


Asunto(s)
Cromatina , Proteína Quinasa Activada por ADN , Autoantígeno Ku , Cromatina/metabolismo , Autoantígeno Ku/metabolismo , Humanos , Proteína Quinasa Activada por ADN/metabolismo , Proteínas de Unión al ADN/metabolismo , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo
11.
J Sci Food Agric ; 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-39011860

RESUMEN

BACKGROUND: Chemical fortification and dose supplementation of vitamin B12 are widely implemented to combat deficiency symptoms. However, in situ, fortification of vitamin B12 in food matrixes can be a promising alternative to chemical fortification. The present study aimed to produce vitamin B12-rich, probiotic guava juice fermented with Levilactobacillus brevis strain KU15152. Pasteurized fresh guava juice was inoculated with 7.2 log CFU mL-1 L. brevis strain KU15152 and incubated for 72 h at 37 °C anaerobically. The antioxidants, total phenolic compounds, vitamin B12 production, sugars, organic acids, pH and viable count were analyzed at 24, 48 and 72 h of incubation. The fermented juice was stored at 4 °C, and the changes in its functional properties were analyzed at 7-day intervals up to 28 days of storage. RESULTS: During fermentation, the bacteria cell count was increased from 7.01 ± 0.06 to 9.76 ± 0.42 log CFU mL-1 after 72 h of fermentation and was decreased to 6.94 ± 0.34 CFU mL-1 during storage at 4 °C after 28 days. The pH, total soluble solids, crude fiber, citric acid and total sugars decreased, while titratable acidity, total protein, antioxidants, phenolic compounds and lactic acid contents increased during fermentation. The fermented guava juice exhibited higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS)) radical scavenging activities (85.97% and 75.97%, respectively) at 48 h of fermentation. The concentration of active vitamin B12 in the sample reached 109.5 µg L-1 at 72 h of fermentation. However, this concentration gradually decreased to 70.2 µg L-1 during the storage period. During storage for 28 days at 4 °C, both the fermented and control guava juices exhibited a decline in antioxidant and phenolic compound concentrations. Furthermore, the addition of 20% honey and guava flavor enhanced the organoleptic properties and acceptability of fermented guava juice. CONCLUSION: The value-added fermented guava juice could be a novel functional food product to combat vitamin B12 deficiency. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

12.
Biosci Biotechnol Biochem ; 88(9): 1109-1116, 2024 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-38889935

RESUMEN

The basidiomycetous yeast Pseudozyma tsukubaensis is known as an industrial mannosylerythritol lipid producer. In this study, the PtURA5 marker gene was deleted by homologous recombination. Using the PtURA5-deleted mutant as a host strain, we obtained a derivative disrupted for the PtKU70 gene, a putative ortholog of the KU70 gene encoding a protein involved in the nonhomologous end-joining pathway of DNA repair. Subsequently, the introduced PtURA5 gene was re-deleted by marker recycling. These results demonstrated that the PtURA5 gene can be used as a recyclable marker gene. Although the frequency of homologous recombination has been shown to be increased by KU70 disruption in other fungi, the PtKU70-disrupted strain of P. tsukubaensis did not demonstrate an elevated frequency of homologous recombination. Furthermore, the PtKU70-disrupted strain did not show increased susceptibility to bleomycin. These results suggested that the function of this KU70 ortholog in P. tsukubaensis is distinct from that in other fungi.


Asunto(s)
Glucolípidos , Recombinación Homóloga , Autoantígeno Ku , Autoantígeno Ku/metabolismo , Autoantígeno Ku/genética , Glucolípidos/biosíntesis , Glucolípidos/metabolismo , Ustilaginales/genética , Ustilaginales/metabolismo , Bleomicina/farmacología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Marcadores Genéticos , Eliminación de Gen
13.
DNA Repair (Amst) ; 140: 103710, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38901287

RESUMEN

The KU heterodimer (KU70/80) is rapidly recruited to DNA double-strand breaks (DSBs) to regulate their processing and repair. Previous work has revealed that the amino-terminal von Willebrand-like (vWA-like) domain in KU80 harbours a conserved hydrophobic pocket that interacts with a short peptide motif known as the Ku-binding motif (KBM). The KBM is present in a variety of DNA repair proteins such as APLF, CYREN, and Werner protein (WRN). Here, to investigate the importance of KBM-mediated protein-protein interactions for KU80 function, we employed KU80-deficient Chinese Hamster Ovary (Xrs-6) cells transfected with RFP-tagged wild-type human KU80 or KU80 harbouring a mutant vWA-like domain (KU80L68R). Surprisingly, while mutant RFP-KU80L68R largely or entirely restored NHEJ efficiency and radiation resistance in KU80-deficient Xrs-6 cells, it failed to restore cellular resistance to DNA replication stress induced by camptothecin (CPT) or hydroxyurea (HU). Moreover, KU80-deficient Xrs-6 cells expressing RFP-KU80L68R accumulated pan-nuclear γH2AX in an S/G2-phase-dependent manner following treatment with CPT or HU, suggesting that the binding of KU80 to one or more KBM-containing proteins is required for the processing and/or repair of DNA ends that arise during DNA replication stress. Consistent with this idea, depletion of WRN helicase/exonuclease recapitulated the CPT-induced γH2AX phenotype, and did so epistatically with mutation of the KU80 vWA-like domain. These data identify a role for the KBM-binding by KU80 in the response and resistance of CHO cells to arrested and/or collapsed DNA replication forks, and implicate the KBM-mediated interaction of KU80 with WRN as a critical effector of this role.


Asunto(s)
Cricetulus , Replicación del ADN , Autoantígeno Ku , Autoantígeno Ku/metabolismo , Autoantígeno Ku/genética , Animales , Células CHO , Humanos , Cricetinae , Roturas del ADN de Doble Cadena , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Helicasa del Síndrome de Werner/metabolismo , Helicasa del Síndrome de Werner/genética , Reparación del ADN por Unión de Extremidades , Unión Proteica , Camptotecina/farmacología , Hidroxiurea/farmacología
14.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 32(3): 875-882, 2024 Jun.
Artículo en Chino | MEDLINE | ID: mdl-38926983

RESUMEN

OBJECTIVE: This study was aimed to provide ideas for identifying the antibodies to high-frequency antigens by analyzing a female case of high-frequency antigen antibody (anti-Ku) using serological and sequencing method. METHODS: The methods for identification of blood group, erythrocyte antigen, screening and identification of antibody were used to detect the blood type and antibody in the proband. The proband's serum and reagent screening cells treated with Sulfhydryl reagent were applied to judge the type and characteristics of this antibodies when reacted with the regaent screening cells or proband's serum respectively. Gene sequencing was used to determine the genotype of the proband's blood group. RESULTS: The proband's red blood cells were determined as O type RhD positive, whose serum showed strong positive reaction to antibody-screening cells and antibody identification cells with the same intensity in saline and IAT medium, however, the self-cells showed negative effect. The Direct Antihuman Globulin of proband's red blood cells also showed weak positive reaction, and the other blood types were CcEe, Jk(a+b-), P1-, Le(a-b -), Lu (a-b +), K-, k-, Kp(a-b-). Serum of the proband treated with 2-ME still react with three groups of screening cells in IAT medium. The reaction intensity of proband's serum was also unchanged with the cells modified with papain and bromelain, but showed negative effect when the cells were treated with sulfhydryl agents including DTT and 2-ME. Gene sequencing revealed that the KEL genotype of the patient was KEL*02N.24 . This patient had a rare K0 phenotype. CONCLUSION: The rare Kell-null blood group (also known as K0) were identified by serological and molecular tests in the proband who produced both IgG and IgM type of antibody to high-frequency antigen (anti-Ku). These two methods are of great significance in the identification of this rare blood group as well as the antibody to high frequency antigen.


Asunto(s)
Eritrocitos , Humanos , Femenino , Eritrocitos/inmunología , Antígenos de Grupos Sanguíneos/inmunología , Tipificación y Pruebas Cruzadas Sanguíneas , Genotipo , Autoantígeno Ku/inmunología , Anticuerpos
15.
Sci China Life Sci ; 67(6): 1089-1105, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38842635

RESUMEN

Histone H3 Lys36 (H3K36) methylation and its associated modifiers are crucial for DNA double-strand break (DSB) repair, but the mechanism governing whether and how different H3K36 methylation forms impact repair pathways is unclear. Here, we unveil the distinct roles of H3K36 dimethylation (H3K36me2) and H3K36 trimethylation (H3K36me3) in DSB repair via non-homologous end joining (NHEJ) or homologous recombination (HR). Yeast cells lacking H3K36me2 or H3K36me3 exhibit reduced NHEJ or HR efficiency. yKu70 and Rfa1 bind H3K36me2- or H3K36me3-modified peptides and chromatin, respectively. Disrupting these interactions impairs yKu70 and Rfa1 recruitment to damaged H3K36me2- or H3K36me3-rich loci, increasing DNA damage sensitivity and decreasing repair efficiency. Conversely, H3K36me2-enriched intergenic regions and H3K36me3-enriched gene bodies independently recruit yKu70 or Rfa1 under DSB stress. Importantly, human KU70 and RPA1, the homologs of yKu70 and Rfa1, exclusively associate with H3K36me2 and H3K36me3 in a conserved manner. These findings provide valuable insights into how H3K36me2 and H3K36me3 regulate distinct DSB repair pathways, highlighting H3K36 methylation as a critical element in the choice of DSB repair pathway.


Asunto(s)
Roturas del ADN de Doble Cadena , Reparación del ADN por Unión de Extremidades , Histonas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Histonas/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Humanos , Metilación , Autoantígeno Ku/metabolismo , Autoantígeno Ku/genética , Proteína de Replicación A/metabolismo , Proteína de Replicación A/genética , Recombinación Homóloga , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Reparación del ADN , Cromatina/metabolismo , Cromatina/genética
16.
bioRxiv ; 2024 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-38915611

RESUMEN

Telomeric DNA, composed of short, direct repeats, is of crucial importance for chromosome stability. Due to intrinsic problems with replicating this DNA, the repeat tracts shorten at each cell division. Once repeat tracts become critically short, a telomeric stress signal induces cellular senescence and division arrest, which eventually may lead to devastating age-related degenerative diseases associated with dysfunctional telomers. Conversely, maintenance of telomere length by telomerase upregulation is a hallmark of cancer. Therefore, telomere length is a critical determinant of telomere function. How telomere length is established and molecular mechanisms for telomere-specific length regulation remained unknown. Here we show that subtelomeric chromatin is a determinant for how telomere equilibrium set-length is established in cis. The results demonstrate that telomerase recruitment mediated by the telomere-associated Sir4 protein is modulated on chromosome 3L in a telomere-specific way. Increased Sir4 abundance on subtelomeric heterochromatin of this specific telomere leads to telomere lengthening of only that telomere in cis, but not at other telomeres. Therefore, this work describes a mechanism for a how telomere-specific repeat tract length can be established. Further, our results will force the evaluation of telomere length away from a generalized view to a more telomere-specific consideration.

17.
Eur J Pharmacol ; 975: 176647, 2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-38754534

RESUMEN

The emergence of chemoresistance poses a significant challenge to the efficacy of DNA-damaging agents in cancer treatment, in part due to the inherent DNA repair capabilities of cancer cells. The Ku70/80 protein complex (Ku) plays a central role in double-strand breaks (DSBs) repair through the classical non-homologous end joining (c-NHEJ) pathway, and has proven to be one of the most promising drug target for cancer treatment when combined with radiotherapy or chemotherapy. In this study, we conducted a high-throughput screening of small-molecule inhibitors targeting the Ku complex by using a fluorescence polarization-based DNA binding assay. From a library of 11,745 small molecules, UMI-77 was identified as a potent Ku inhibitor, with an IC50 value of 2.3 µM. Surface plasmon resonance and molecular docking analyses revealed that UMI-77 directly bound the inner side of Ku ring, thereby disrupting Ku binding with DNA. In addition, UMI-77 also displayed potent inhibition against MUS81-EME1, a key player in homologous recombination (HR), demonstrating its potential for blocking both NHEJ- and HR-mediated DSB repair pathways. Further cell-based studies showed that UMI-77 could impair bleomycin-induced DNA damage repair, and significantly sensitized multiple cancer cell lines to the DNA-damaging agents. Finally, in a mouse xenograft tumor model, UMI-77 significantly enhanced the chemotherapeutic efficacy of etoposide with little adverse physiological effects. Our work offers a new avenue to combat chemoresistance in cancer treatment, and suggests that UMI-77 could be further developed as a promising candidate in cancer treatment.


Asunto(s)
Antineoplásicos , Autoantígeno Ku , Humanos , Autoantígeno Ku/metabolismo , Animales , Línea Celular Tumoral , Ratones , Antineoplásicos/farmacología , Antineoplásicos/química , Daño del ADN/efectos de los fármacos , Simulación del Acoplamiento Molecular , Ensayos Antitumor por Modelo de Xenoinjerto , Reparación del ADN por Unión de Extremidades/efectos de los fármacos , Etopósido/farmacología , Descubrimiento de Drogas , Roturas del ADN de Doble Cadena/efectos de los fármacos , Resistencia a Antineoplásicos/efectos de los fármacos
18.
Network ; : 1-31, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38804502

RESUMEN

The recent wireless communication systems require high gain, lightweight, low profile, and simple antenna structures to ensure high efficiency and reliability. The existing microstrip patch antenna (MPA) design approaches attain low gain and high return loss. To solve this issue, the geometric dimensions of the antenna should be optimized. The improved Particle Swarm Optimization (PSO) algorithm which is the combination of PSO and simulated annealing (SA) approach (PSO-SA) is employed in this paper to optimize the width and length of the inset-fed rectangular microstrip patch antennas for Ku-band and C-band applications. The inputs to the proposed algorithm such as substrate height, dielectric constant, and resonant frequency and outputs are optimized for width and height. The return loss and gain of the antenna are considered for the fitness function. To calculate the fitness value, the Feedforward Neural Network (FNN) is employed in the PSO-SA approach. The design and optimization of the proposed MPA are implemented in MATLAB software. The performance of the optimally designed antenna with the proposed approach is evaluated in terms of the radiation pattern, return loss, Voltage Standing Wave Ratio (VSWR), gain, computation time, directivity, and convergence speed.

19.
Neuromuscul Disord ; 40: 7-15, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38805897

RESUMEN

Anti-Ku autoantibodies are associated with several autoimmune inflammatory diseases. We aimed to review our anti-Ku positive pediatric patients in this study. Four pediatric patients (all female) who had anti-Ku positivity were included (Patients 1-2-3 with idiopathic inflammatory myopathy (IIM); Patient 4 with chronic urticaria). Patient 1 (onset:10.5 years) had proximal muscle weakness, Raynaud phenomenon, sclerodactyly, hyperpigmentation, joint contracture, and tenosynovitis. The disease course was progressive despite treatment with corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, and 11 different immunosuppressive drugs. Patient 2 (onset:15 years) presented with proximal muscle weakness, fatigue, weight loss. She recovered normal muscle strength after treatment with corticosteroids, IVIG, methotrexate, cyclosporine A, mycophenolate mofetil. Patient 3 (onset:10 years) had juvenile dermatomyositis with proximal muscle weakness, Gottron's papules, and calcinosis. She also had anti-NXP2 positivity. Remission was achieved with corticosteroids, methotrexate, azathioprine, and infliximab. Muscle biopsy findings revealed a variable spectrum of necrosis, regeneration, perifascicular pattern, and inflammation. Patient 4 had only chronic urticaria (onset: 6.5 years). The striking features of this series were heterogeneity in clinical presentations including solely chronic urticaria and IIM; variable response to immunosuppressive treatments; and histopathology revealing a spectrum of necrosis, regeneration and inflammatory infiltration. Expanding the spectrum of anti-Ku positivity will allow better understanding of anti-Ku-associated phenotype clusters.


Asunto(s)
Autoanticuerpos , Autoantígeno Ku , Fenotipo , Humanos , Femenino , Adolescente , Niño , Autoantígeno Ku/inmunología , Autoanticuerpos/sangre , Miositis/inmunología , Miositis/tratamiento farmacológico , Urticaria Crónica/tratamiento farmacológico , Urticaria Crónica/inmunología
20.
Clin Rheumatol ; 43(6): 2145-2152, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38652335

RESUMEN

The frequency of antibodies to Ku varies in various autoimmune diseases. In 2019, Spielmann et al. identified two types of anti-Ku syndrome based on a hierarchical clustering analysis. Sjögren's syndrome occurs both in the first type of anti-Ku syndrome and in the second type. Despite the fact that increased tissue expression of Ku proteins was noted in lymphocytic cells with focal sialoadenitis of the minor salivary glands in patients with primary Sjogren's syndrome, only 49 cases of a combination of anti-Ku antibodies and manifestations of Sjogren's syndrome have been described in the literature. Some researchers examined patients for the presence of Sjogren's syndrome only if they had anti-Ro or anti-La antibodies, although in the literature, there are descriptions of Sjogren's syndrome in the presence of only isolated anti-Ku antibodies, as in our case. Literature data on glandular and extraglandular manifestations of Sjögren's syndrome in anti-Ku-positive patients are limited. Below, we present the first case of Sjögren's syndrome in combination with the first type of anti-Ku syndrome complicated by the development of mucosa-associated lymphoid tissue (MALT) lymphoma. The article also provides a systematic review of the literature on the association of Sjögren's syndrome with anti-Ku antibodies.


Asunto(s)
Autoantígeno Ku , Linfoma de Células B de la Zona Marginal , Síndrome de Sjögren , Humanos , Síndrome de Sjögren/complicaciones , Síndrome de Sjögren/inmunología , Linfoma de Células B de la Zona Marginal/complicaciones , Linfoma de Células B de la Zona Marginal/inmunología , Femenino , Autoantígeno Ku/inmunología , Persona de Mediana Edad , Autoanticuerpos/inmunología
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