Chromosomal DNA Research Articles

Camptothecin Triggers Apoptosis in Human and Mouse Drug-resistant Glioblastoma Cells via ROS-mediated Activation of the p53-p21-CD1/CDK2-E2F1-Bcl-xL Signaling Axis.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor. Temozolomide (TMZ) is the first-line treatment for GBM. However, most patients with GBM develop drug resistance. Our previous study showed the effects of camptothecin (CPT) and CRLX101, a nanoparticle of CPT, in suppressing GBM growth by targeting drug-sensitive glioblastoma cells. This study evaluated the effects of CPT on drug-resistant glioblastoma cells and explored the underlying molecular mechanisms. Expression of type I topoisomerase (Topo-1) gene in GBM was analyzed using the UALCAN database. Human U87MG-R and mouse GL261-R TMZ-resistant glioblastoma cells were developed. After CPT treatment, apoptotic events were successively determined. The role of the p53-p21-cyclin D1 (CD1)/cyclin-dependent kinase 6 (CDK6)-E2F1-Bcl-xL signaling axis was subsequently investigated. The expression of Topo-1 gene was up-regulated in human GBM compared to normal human brains. Treatment of human U87MG-R cells with CPT decreased cell viability. Sequentially, exposure to CPT led to activation of caspase-3, fragmentation of chromosomal DNA, and cell apoptosis. Furthermore, intracellular reactive oxygen species (iROS) were augmented following CPT treatment. Suppression of iROS production concurrently alleviated CPT-triggered apoptotic insults. CPT enhanced the levels of p53, phosphorylated p53, and p21. In contrast, levels of CDK6, CD1, E2F1, and Bcl-xL were decreased by CPT. Attenuating p53 transactivation activity using pifithrin-α also mitigated the CPT-induced apoptosis. The effects of CPT on killing drug-resistant glioblastoma cells were further confirmed in mouse GL261-R cells. CPT could effectively induce apoptosis in drug-resistant glioblastoma cells via iROS-mediated activation of the p53-p21-CD1/CDK6-E2F1-Bcl-xL axis.

Early onset of septal FtsK localization allows for efficient DNA segregation in SMC-deleted Corynebacterium glutamicum strains.

Structural maintenance of chromosomes (SMC) are ubiquitously distributed proteins involved in chromosome organization. Deletion of smc causes severe growth phenotypes in many organisms. Surprisingly, smc can be deleted in Corynebacterium glutamicum, a member of the Actinomycetota phylum, without any apparent growth phenotype. SMC in C. glutamicum is loaded in a ParB-dependent fashion to the chromosome and functions in replichore cohesion. The unexpected absence of a growth phenotype in the smc mutant prompted us to screen for synthetic interactions within C. glutamicum. We generated a high-density Tn5 library from wild-type and smc-deleted C. glutamicum strains. Transposon sequencing data revealed that the DNA translocase FtsK is essential in an smc-deletion strain. In wild-type cells, FtsK localized to the septa and cell poles, showing polar enrichment during the earlier stages of the life cycle and relocating to the septum in the later stages. However, deletion of smc resulted in an earlier onset of pole-to-septum FtsK relocation, suggesting that prolonged FtsK complex activity is both required and sufficient to compensate for the absence of SMC, thus achieving efficient chromosome segregation in C. glutamicum. Deletion of ParB increases SMC and FtsK mobility. While the change in SMC dynamics aligns with previous data showing ParB's role in SMC loading on DNA, the change in FtsK mobility suggests defects in chromosome segregation. Based on our data, we propose an efficient mechanism for reliable DNA segregation in the absence of replichore arm cohesion in smc mutant cells.IMPORTANCEFaithful DNA segregation is of fundamental importance for life. Bacteria have developed efficient systems to coordinate chromosome compaction, DNA segregation, and cell division. A key factor in DNA compaction is the SMC complex that is found to be essential in many bacteria. In members of the Actinomycetota, smc is dispensable, but the reason for the lack of an smc phenotype in these bacteria remained unclear. We show here that the divisome-associated DNA pump FtsK can compensate for SMC loss and the subsequent loss in correct chromosome organization. In cells with distorted chromosomes, FtsK is recruited and stabilized earlier to the septum, allowing for DNA segregation for a larger part of the cell cycle, until chromosomes are segregated.

TMEM160 Promotes Tumor Growth in Lung Adenocarcinoma and Cervical Adenocarcinoma Cell Lines

The Chromosome-Centric Human Proteome Project (C-HPP) is an international initiative. It aims to create a protein list expressed in human cells by each chromosomal and mitochondrial DNA to enhance our understanding of disease mechanisms, akin to the gene list generated by the Human Genome Project. Transmembrane protein 160 (TMEM160) is a member of the transmembrane proteins (TMEM) family. TMEM proteins have been implicated in cancer-related processes, including cell proliferation, migration, epithelial-mesenchymal transition, metastasis, and resistance to chemotherapy and radiotherapy. This study aimed to investigate the role of TMEM160 in non-small cell lung cancer and cervical cancer using cell lines, clinical samples, and xenograft studies. Our findings demonstrated that TMEM160 knockdown decreased the proliferation of lung and cervical cancer cell lines. We observed that TMEM160 is localized in the nucleus and cytoplasm and dynamic localization during mitosis of cancer cells and discovered a novel interaction between TMEM160 and nuclear proteins such as NUP50. Furthermore, the TMEM160 interactome was enriched in processes associated with apical junctions, xenobiotic metabolism, glycolysis, epithelial-mesenchymal transition, reactive oxygen species, UV response DNA, the P53 pathway, and the mitotic spindle. This study provides an initial understanding of the function of TMEM160 in lung and cervical cancer progression and clarifies the need to continue investigating the participation of TMEM160 in these cancers.

A dual role of Cohesin in DNA DSB repair

Cells undergo tens of thousands of DNA-damaging events each day. Defects in repairing double-stranded breaks (DSBs) can lead to genomic instability, contributing to cancer, genetic disorders, immunological diseases, and developmental defects. Cohesin, a multi-subunit protein complex, plays a crucial role in both chromosome organization and DNA repair by creating architectural loops through chromatin extrusion. However, the mechanisms by which cohesin regulates these distinct processes are not fully understood. In this study, we identify two separate roles for cohesin in DNA repair within mammalian cells. First, cohesin serves as an intrinsic architectural factor that normally prevents interactions between damaged chromatin. Second, cohesin has an architecture-independent role triggered by ATM phosphorylation of SMC1, which enhances the efficiency of repair. Our findings suggest that these two functions work together to reduce the occurrence of translocations and deletions associated with non-homologous end joining, thereby maintaining genomic stability.

Cyto-Genotoxic Assessment of Sulfoxaflor in Allium cepa Root Cells and DNA Docking Studies.

Sulfoxaflor (SFX) is an insecticide that is commonly used for the control of sap-feeding insects. Since SFX is extensively applied globally, it has been implicated in the substantial induction of environmental toxicity. Therefore, in this study, Allium cepa roots have been employed to elucidate the potential cytogenotoxic effects of SFX in non-target cells by examination of mitotic index (MI), chromosomal aberrations (CAs), and DNA damage. Physiological effects of SFX were evaluated by A. cepa root growth inhibition assay, while cytogenotoxic effects were assessed by A. cepa ana-telophase and comet assay. Moreover, DNA binding affinity and binding mode of SFX were examined using molecular docking simulations to shed light on the genotoxic mechanism of action. The half maximal effective concentration (EC50) on the growth of A. cepa cells calculated for SFX was found as 500 mg/L. Moreover, dose- and time-dependent decrease in MI, increase in CAs (disturbed ana-telophase, chromosomal laggards, stickiness, and anaphase chromosome bridge) and DNA damage were observed by the exposure of A. cepa root tips to SFX after 24-, 48-, 72-, and 96-h treatment periods. A 6-bp double-stranded DNA structure containing two intercalation sites (PDB ID: 1Z3F) was used for docking studies. According to DNA docking results, SFX exhibited an energetically more favorable binding affinity with DNA (ΔG = -5.05 kcal/mol) compared with the experimental mutagen methyl methanesulfonate (MMS) (ΔG = -2.94 kcal/mol), and preferentially snugly fits into the minor groove of DNA possessing an intercalation gap, thus, providing valuable mechanistic data into the formation of chromosome aberrations and DNA fragmentation induced by this pesticide in A. cepa.

Global insights into the genome dynamics of Clostridioides difficile associated with antimicrobial resistance, virulence, and genomic adaptations among clonal lineages.

Clostridioides difficile is a significant cause of healthcare-associated infections, with rising antimicrobial resistance complicating treatment. This study offers a genomic analysis of C. difficile, focusing on sequence types (STs), global distribution, antibiotic resistance genes, and virulence factors in its chromosomal and plasmid DNA. A total of 19,711 C. difficile genomes were retrieved from GenBank. Prokka was used for genome annotation, and multi-locus sequence typing (MLST) identified STs. Pan-genome analysis with Roary identified core and accessory genes. Antibiotic resistance genes, virulence factors, and toxins were detected using the CARD and VFDB databases, and the ABRicate software. Statistical analyses and visualizations were performed in R. Among 366 identified STs, ST1 (1,326 isolates), ST2 (1,141), ST11 (893), and ST42 (763) were predominant. Trends of genome streamlining included reductions in chromosomal length, gene count, protein-coding genes, and pseudogenes. Common antibiotic resistance genes-cdeA (99.46%), cplR (99.63%), and nimB (99.67%)-were nearly ubiquitous. Rare resistance genes like blaCTX-M-2, cfxA3, and blaZ appeared in only 0.005% of genomes. Vancomycin susceptibility-reducing vanG cluster genes were detected at low frequencies. Virulence factors showed variability, with highly prevalent genes such as zmp1 (99.62%), groEL (99.60%), and rpoB/rpoB2 (99.60%). Moderately distributed genes included cwp66 (54.61%) and slpA (79.02%). Toxin genes tcdE (91.26%), tcdC (89.67%), and tcdB (89.06%) were widespread, while binary toxin genes cdtA (26.19%) and cdtB (26.26%) were less common. Toxin gene prevalence, particularly tcdA and tcdB, showed a gradual decline over time, with sharper reductions for cdtA and cdtB. Gene presence patterns (GPP-1) for resistance, virulence, and toxin genes were primarily linked to ST2, ST42, and ST8. This study highlights C. difficile's adaptability and genetic diversity. The decline in toxin genes reflects fewer toxigenic isolates, but the bacterium's increasing preserved resistance factors and virulence genes enable its rapid evolution. ST2, ST42, and ST8 dominate globally, emphasizing the need for ongoing monitoring.

Cell integrity limits ploidy in budding yeast

Abstract Evidence suggests that increases in ploidy have occurred frequently in the evolutionary history of organisms and can serve adaptive functions to specialized somatic cells in multicellular organisms. However, the sudden multiplication of all chromosome content may present physiological challenges to the cells in which it occurs. Experimental studies have associated increases in ploidy with reduced cell survival and proliferation. To understand the physiological challenges that suddenly increased chromosome content imposes on cells, we used S. cerevisiae to ask how much chromosomal DNA cells may contain and what determines this limit. We generated polyploid cells using 2 distinct methods causing cells to undergo endoreplication and identified the maximum ploidy of these cells, 32–64C. We found that physical determinants that alleviate or exacerbate cell surface stress increase and decrease the limit to ploidy, respectively. We also used these cells to investigate gene expression changes associated with increased ploidy and identified the repression of genes involved in ergosterol biosynthesis. We propose that ploidy is inherently limited by the impacts of growth in size, which accompany whole-genome duplication, to cell surface integrity.

The Construction of Heterothallic Strains of Komagataella kurtzmanii Using the I-SceI Meganuclease.

The methylotrophic yeast Komagataella kurtzmanii belongs to the group of homothallic fungi that are able to spontaneously change their mating type by inversion of chromosomal DNA in the MAT locus region. As a result, natural and genetically engineered cultures of these yeasts typically contain a mixture of sexually dimorphic cells that are prone to self-diploidisation and spore formation accompanied by genetic rearrangements. These characteristics pose a significant challenge to the development of genetically stable producers for industrial use. In the present study, we constructed heterothallic strains of K. kurtzmanii, ensuring a constant mating type by unifying the genetic sequences in the active and silent MAT loci. To obtain such strains, we performed site-directed inactivation of one of the two yeast MAT loci, replacing its sequence with a selective HIS4 gene surrounded by I-SceI meganuclease recognition sites. We then used transient expression of the SCE1 gene, encoding a recombinant I-SceI meganuclease, to induce site-specific cleavage of HIS4, followed by damage repair by homologous recombination in mutant cells. As a result, heterothallic strains designated 'Y-727-2(alpha)' and 'Y-727-9(a)', which correspond to the α and a mating type, respectively, were obtained. The strains demonstrated a loss of the ability to self-diploidize. The results of PCR and whole genome analysis confirmed the identity of the contents of the MAT loci. Analysis of the genomes of the final strains, however, revealed a fusion of chromosome 3 and chromosome 4 in strain Y-727-2(alpha)-1. This finding was subsequently confirmed by pulsed-field gel electrophoresis of yeast chromosomes. However, the ability of the Y-727-2(alpha)-derived producers to efficiently secrete recombinant β-galactosidase was unaffected by this genomic rearrangement.

DciA, the Bacterial Replicative Helicase Loader, promotes LLPS in the presence of ssDNA

The loading of the bacterial replicative helicase DnaB is an essential step for genome replication and depends on the assistance of accessory proteins. Several of these proteins have been identified across the bacterial phyla. DciA is the most common loading protein in bacteria, yet the one whose mechanism is the least understood. We have previously shown that DciA from Vibrio cholerae is composed of a globular domain followed by an unfolded extension and demonstrated its strong affinity for DNA. Here, we characterize the condensates formed by VcDciA upon interaction with a short single-stranded DNA substrate. We demonstrate the fluidity of these condensates using light microscopy and address their network organization through electron microscopy, thereby bridging events to conclude on a liquid-liquid phase separation behavior. Additionally, we observe the recruitment of DnaB in the droplets, concomitant with the release of DciA. We show that the well-known helicase loader DnaC from Escherichia coli is also competent to form these phase-separated condensates in the presence of ssDNA. Our phenomenological data are still preliminary as regards the existence of these condensates in vivo, but open the way for exploring the potential involvement of DciA in the formation of non-membrane compartments within the bacterium to facilitate the assembly of replication players on chromosomal DNA.

Trajectory of human migration: insights from autosomal and non-autosomal variant clustering patterns

Genetic variations present in the Y chromosomal and mitochondrial DNA provide the mole-cular basis to support the archeological and anthropological evidence that formulates the theories for describing the trajectory of human migration, which started almost 200,000 years ago out of Africa. These genetic variations have long been used as ancestry informative markers (AIMs) in forensics and evolutionary studies, primarily because of their uniparental inheritance and lack of recombination, despite the fact that gender-specific gene flow and socio-cultural practices may cause discrepancies. Moreover, the genetic markers on the Y chromosome constitute only a minor fraction of the entire human genome. Here, we analyzed over 75 million genetic variants (single nucleotide variants (SNVs) and short insertion-deletion (InDels)) within consecutive 2500000 base pair windows in the autosomal as well as non-autosomal chromosomes of 22 populations in four major geographic regions that are cataloged in the 1000 Genomes Project to understand the clustering patterns of the autosomal and non-autosomal variants. While autosomal and X-chromosomal variants cluster the populations of similar geographic regions together, Y-chromosomal variants constantly place the East Asian Japanese and the European Finnish populations in a single clade in hierarchical clusters. This comprehensive genome-wide analysis essentially introduces new insights into mapping the path of human migration based on the Y-chromosomal and other chromosomal variants.

Cytidine analogs in plant epigenetic research and beyond.

Cytosine (DNA) methylation plays important roles in silencing transposable elements, plant development, genomic imprinting, stress responses, and maintenance of genome stability. To better understand the functions of this epigenetic modification, several tools have been developed to manipulate DNA methylation levels. These include mutants of DNA methylation writers and readers, targeted manipulation of locus-specific methylation, and the use of chemical inhibitors. Here, we summarize the effects of commonly used cytidine analog chemical inhibitors represented by zebularine, 5-azacytidine, and their related compounds on plants. These analogs are incorporated into the chromosomal DNA, where they block the activity of the replicative CG DNA methyltransferase 1 (MET1). This leads to manifold alterations in plant epigenome, modified developmental programs, or suppression of hybridization barriers. We also highlight the DNA-damaging effects of cytidine analogs, particularly the formation of stable DNA-protein crosslinks between DNA and MET1. This sheds new light on specific phenotypes observed upon cytidine analog treatments. In conclusion, cytidine analogs remain a vital tool for plant genome research and have the potential to open new promising avenues for applications in plant biotechnology and breeding.

Allium chromosome evolution and DNA sequence localization.

Molecular cytogenetics, utilizing DNA probes, serves as a critical tool for mapping genes to the physical structures of chromosomes. In this study, we examined three Allium species: A. cepa L., A. sativum L., and A. fistulosum L., using in situ hybridization to localize 45S rDNA and 5S rDNA genes. We observed variation in both the chromosomal localization and signal intensity of the 45S and 5S rDNA probes across the species. Notably, in A. sativum, additional 5S rDNA signals were detected on chromosome 8, in a heterozygous condition. Additionally, we aimed to explore the feasibility of localizing genes associated with pigment biosynthesis in A. cepa, specifically the PAL and FLS genes. For this, we employed TSA-FISH on both meiotic and mitotic chromosomes. Preliminary results suggested that the PAL gene was localized to meiotic metaphase chromosomes, while the single-copy FLS gene was detected on mitotic chromosomes. The TSA-FISH technique proved neither routine nor robust for consistent localization of these specific probes in plant chromosomes. The findings based on rDNA analysis also offer insights into potential evolutionary implications among the different Allium species studied.

Coselection of BAC for Escherichia coli chromosomal DNA multiplex automated genome engineering.

Recombineering (recombination-mediated genetic engineering) is a powerful strategy for bacterial genomic DNA and plasmid DNA modifications. CoS-MAGE improved over MAGE (multiplex automated genome engineering) by co-electroporation of an antibiotic resistance repair oligo along with the oligos for modification of the Escherichia coli chromosome. After several cycles of recombineering, the sub-population of mutants were selected among the antibiotic resistant colonies. However, a pre-generated strain with mutS deletion and multiple inactivated antibiotic resistance genes integration is required. Herein, CoS-MAGE was modified by employing a single copy BAC vector harboring a bla-mkan cassette and a Red helper vector cloned with dominant mutL E32K, thus bypassing the utilization of the pre-generated strain. The proof-of-concept of the new strategy, CoS-BAC-MAGE, was demonstrated via the mutation of non-essential genes, essential genes, and AT rich regions of the wild type strain E. coli MG1655. With this system, an editing efficiency of 60% was realized. Furthermore, by toggling between two antibiotic resistance genes (one active, the other defective) on the BAC, sequential mutations were achieved without the requirement of BAC vector elimination and re-transformation. Via CoS-BAC-MAGE, simultaneously mutations of three sites were obtained in a day. We envision that CoS-BAC-MAGE will be a practical improvement for the generation of chromosomal mutations using the Cos-MAGE approach.

Genetic profiling of multidrug-resistant Acinetobacter baumannii from a tertiary care center in Malaysia.

Genetic characterization of multidrug-resistant (MDR) Acinetobacter baumannii remains scarce in Malaysia. This study aimed to characterize antibiotic resistance, genomic location, and genetic relatedness among the A. baumannii isolates obtained from a tertiary hospital in Malaysia. A total of 128 MDR A. baumannii isolates were collected from patients admitted to various wards (intensive care unit [ICU], neonatal intensive care unit, coronary care unit, high dependency ward [HDW], and general wards). The isolates were identified by Vitek 2 and PCR amplification of the 16S rRNA gene followed by sequencing. The isolates were tested against imipenem, ceftazidime, amikacin, gentamicin, ampicillin, and ciprofloxacin using disk diffusion, Epsilometer test, and broth microdilution. The antibiotic resistance genes, blaOXA-23, blaOXA-24, blaADC, blaVIM, and blaIMP, were detected in chromosomal and plasmid DNA using PCR. Insertion sequence ISAba1/blaOXA-23 gene was detected on chromosomal DNA only. Isolates with different antibiotic susceptibility patterns and PCR profiles were subjected to multi-locus sequence typing. MDR A. baumannii was predominantly found in HDW (39.84%), general wards (29.69%), and ICU (28.13%). All isolates conferred resistance to carbapenem and more than 90% resistance to the remaining antibiotics. The antibiotic resistance genes blaOXA-23, blaVIM, and blaADC were detected in both chromosomal and plasmid DNA. The ISAba1/blaOXA-23 gene was detected in 99.22% of the isolates. Four sequence types (STs) were distinguished: ST2 (76.67%), ST164 (10%), ST642 (10%), and ST643 (3.33%). ST164 and ST642 were unique and represent a significant finding in Malaysia's surveillance data. These STs are associated with acquired blaOXA-23, indicating an evolutionary adaptation of A. baumannii within the hospital setting.IMPORTANCEAcinetobacter baumannii is a ubiquitous Gram-negative coccobacillus bacterium that is primarily associated with nosocomial infections that can colonize biotic and abiotic surfaces to enhance cell-to-cell adhesion, ensuring the establishment of infections. To date, the spread of multidrug-resistant A. baumannii (MDRAB) has become rampant and a great concern in the hospital setting, as the available antibiotics are insufficient to treat infections. The antibiotic resistance island resides in a mobile element and rapidly evolved. The antibiotic susceptibility data with its resistance mechanisms would contribute to and facilitate the management and infection control caused by MDRAB.

Analysis of Efflux Pump Contributions and Plasmid-Mediated Genetic Determinants in Ciprofloxacin-Resistant Salmonella.

This study aimed to explore the interactions among genetic determinants influencing ciprofloxacin resistance in Salmonella. Treatment with PAβN, an efflux pump inhibitor, resulted in a 4-32-fold reduction in the minimum inhibitory concentration (MIC) across all 18 ciprofloxacin-resistant Salmonella isolates. Notably, isolates without point mutations reverted from resistance to sensitivity. The efflux pump played a crucial role in resistance development, particularly in serovar Enteritidis, where PAβN treatment caused a more significant MIC reduction (16-32-fold) in five strains carrying the GyrA (Asp87Tyr) mutation, which initially exhibited high MICs (8 μg/mL). Several resistance genes were identified on transferable plasmids: oqxAB and aac(6')-Ib-cr were associated with IncF plasmids in S. Enteritidis, IncA/C plasmids in S. Typhimurium, and IncHI2 plasmids in S. Virchow. Additionally, qnrS1 and/or qepA were carried by IncA/C plasmids in S. Thompson. Whole-genome sequencing revealed the presence of an oqxAB module integrated into the chromosomal DNA of S. Derby. Although the MICs of ciprofloxacin in transconjugants and transformants remained low (1-4 μg/mL), they exceeded the clinical breakpoint for susceptibility. These findings highlight the synergistic impact of efflux pumps and plasmid-mediated resistance mechanisms, contributing to the increasing prevalence of ciprofloxacin resistance and posing a significant threat to food safety.

Integrating chromosome conformation and DNA repair in a computational framework to assess cell radiosensitivity**Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or

Objective.The arrangement of chromosomes in the cell nucleus has implications for cell radiosensitivity. The development of new tools to utilize Hi-C chromosome conformation data in nanoscale radiation track structure simulations allows forin silicoinvestigation of this phenomenon. We have developed a framework employing Hi-C-based cell nucleus models in Monte Carlo radiation simulations, in conjunction with mechanistic models of DNA repair, to predict not only the initial radiation-induced DNA damage, but also the repair outcomes resulting from this damage, allowing us to investigate the role chromosome conformation plays in the biological outcome of radiation exposure.Approach.In this study, we used this framework to generate cell nucleus models based on Hi-C data from fibroblast and lymphoblastoid cells and explore the effects of cell type-specific chromosome structure on radiation response. The models were used to simulate external beam irradiation including DNA damage and subsequent DNA repair. The kinetics of the simulated DNA repair were compared with previous results.Main results.We found that the fibroblast models resulted in a higher rate of inter-chromosome misrepair than the lymphoblastoid model, despite having similar amounts of initial DNA damage and total misrepairs for each irradiation scenario.Significance.This framework represents a step forward in radiobiological modeling and simulation allowing for more realistic investigation of radiosensitivity in different types of cells.

IRF-1 Regulates Mitochondrial Respiration and Intrinsic Apoptosis Under Metabolic Stress through ATP Synthase Ancillary Factor TMEM70.

Mitochondrial dysfunction, which can be caused by metabolic stressors such as oxidized low-density lipoprotein (oxLDL), sensitizes the endothelium to pathological changes. The transcription factor interferonregulatoryfactor 1 (IRF-1) is a master regulator of inflammation, previously shown to promote oxLDL-induced inflammatory pyroptosis in human aortic endothelial cells (HAEC). However, a presumed role for IRF-1 in regulating the intrinsic apoptotic pathway in response to metabolic stress has not been demonstrated. Here targeted deletion of IRF-1 by siRNA in HAEC aggravated oxLDL-induced, mitochondria-mediatedintrinsicapoptosis, as evidenced by increased Caspase-3 and Caspase-9 activation, and chromosomal DNA breakage. The increased apoptosis was concomitant with accumulation of mitochondrial ROS, decrease in intracellular ATP production and respiratory oxygen consumption, and abnormal mitochondrial structure. RNA profiling of endothelial cells isolated from wild type and Irf1 knockout mice, followed by quantitative PCR, luciferase activity assay and chromatin immunoprecipitation (ChIP), revealed that IRF-1 directly regulated the expression of transmembrane protein 70 (TMEM70), an ancillary factor required for the assembly of ATP synthase and conversion of an electrochemical gradient to ATP synthesis. Mirroring the effect of IRF1 knockdown, depletion of TMEM70 in HAEC resulted in impaired mitochondrial function and enhanced cell apoptosis. In contrast, overexpression of TMEM70 rescued ATP biosynthesis and suppressed apoptosis in oxLDL-treated, IRF-1-deficient HAEC. These results reveal a novel homeostatic role for IRF-1 in the regulation of mitochondrial function and associated stress-induced apoptosis.

ALIGNMENT OF PREP USE WITH POTENTIAL HIV EXPOSURE IN YOUNG WOMEN AND MEN IN UGANDA.

Despite high oral pre-exposure prophylaxis (PrEP) uptake among young heterosexual cisgender women, early discontinuation is frequent. It is unclear whether this aligns with potential HIV exposure. Young women 16-25 years and ≥1 of their male partners were enrolled in separate but linked longitudinal HIV PrEP studies in Kampala, Uganda from 2018-2021. Data on sexual behavior, PrEP use, STI positivity, and Y chromosome DNA (Yc DNA; a marker for condomless sex) were collected at enrollment and quarterly visits. Potential HIV exposure was defined as one of the following in the past 3 months: any STI, detection of Yc DNA, condomless vaginal sex, or multiple sex partners. Alignment between potential HIV exposure and PrEP use by participants was examined using GEE regression. 88 young women (median age=20.6, IQR 19.5-22.0) and 124 male partners (median age=23.5, IQR 21.0-26.0) were included. Women and men were dispensed PrEP in 66.9% and 60.5% of their first linked visits, respectively. PrEP dispensation was more common when women or men self-reported condomless vaginal sex and multiple sex partners, or when women had Yc DNA detected in vaginal swabs. Men's self-report of multiple partners (aPR=1.56, p=0.012) and the detection of Yc DNA (aPR=1.52, p=0.040) were significantly associated with women's PrEP dispensation. Women and their male partners may align their PrEP use with their HIV risk behaviors, providing some reassurance that PrEP discontinuation in young people often aligns with sexual behavior. Greater attention to measurement of and mismatches in PrEP discontinuation and potential HIV exposure is needed.

SND1-SMARCA5 interaction strengthened by PIM promotes the proliferation, metastasis, and chemoresistance of esophageal squamous cell carcinoma.

Chromatin remodeling plays a pivotal role in the progression of esophageal squamous cell carcinoma (ESCC), but the precise mechanisms remain poorly understood. Here, we elucidated the critical function of staphylococcal nuclease and tudor domain-containing 1 (SND1) in modulating chromatin dynamics, thereby driving ESCC progression in both in vitro and in vivo models. Our data revealed that SND1 was markedly overexpressed in ESCC cell lines. Silencing SND1 disrupted histone modifications, attenuated RNA polymerase II activity, and precipitated increased chromosomal aberrations and DNA damage, particularly following camptothecin treatment. These molecular perturbations culminated in diminished cellular proliferation, metastasis, and chemoresistance. We further identified that the regulatory effects of SND1 on chromatin were mediated through its interaction with SMARCA5, a process potentiated by PIM1-catalyzed phosphorylation of SND1 at serine 426. This SND1-SMARCA5 interaction was essential for the transcriptional activation of CUX1, a key oncogene implicated in ESCC progression. Notably, disruption of SND1S426 phosphorylation impaired the SND1-SMARCA5 interaction, leading to significant inhibition of ESCC tumor growth and metastatic potential in vivo. Our findings unveil a novel mechanistic axis involving SND1 and SMARCA5 in chromatin remodeling and oncogenesis, offering promising therapeutic targets for ESCC intervention.

Diagnostic status and new explorations in upper urinary tract urothelial carcinoma: a literature review.

Upper urinary tract urothelial carcinomas (UTUCs) are characterized by their obscure location, insidious onset, and propensity for early muscle-invasive and lymph node metastasis, resulting in a generally poor prognosis. Clinically, diagnosis primarily relies on urine cytology, computed tomography urography (CTU), and white light ureteroscopy (WL-URS). These methods, however, suffer from low sensitivity, high cost, inefficient testing, patient discomfort, surgery-related complications, and potential tumor implantation. This literature review summarizes the advantages and disadvantages of the existing diagnostic tools for UTUC and discusses promising advancements in the field. A comprehensive computer-assisted search, supplemented by literature tracing, was conducted to review publications on UTUCs diagnostics from the PubMed, Embase, and Web of Science databases covering the period from 2000 to August 2024. The research focused on synthesizing findings from the selected publications. Over 100 studies were reviewed, spanning from traditional diagnostic methods like urine cytology, CTU, and WL-URS, as well as newer methods including endoscopic advances, biopsy methods, radiomics, immunocytology [urinary tumor cell (UTC) assay], urinary genetic tests (identifying chromosomal abnormalities, DNA mutations, DNA methylation, and RNA), and hematological and urinary tests for microRNAs (miRNAs) and proteins (plasma protein classifiers). While traditional methods have been extensively evaluated, they remain suboptimal in terms of effectiveness, safety, patient satisfaction, and cost. Emerging diagnostics and molecular markers show promise, such as the high sensitivity of the urinary UTC assay for early-stage tumors and the non-invasive nature of various urinary molecular tests, along with the high accuracy of plasma protein classifiers. However, these new tools generally lack thorough evaluation and are often restricted to reports from single institutions or simple differentiation of cancerous cases from controls under experimental conditions. Traditional diagnostic methods for UTUCs exhibit significant limitations, which newer tools and molecular markers are poised to address. However, comprehensive evaluations of these innovations are required to confirm their efficacy.