Search Results (68)

Recent evidence highlights the role of extrachromosomal circular DNAs (eccDNAs) in cancers. However, reports regarding its role in hepatocellular carcinoma (HCC) are infrequent. The abundance of eccDNAs from five HCC/adjacent tissue pairs was explored using Circle-Sequencing. eccDNA PAFAH1B3 was selected as one of the objects. The effect of eccDNA PAFAH1B3 on HCC progression was determined using EdU, Transwell, and apoptosis assays. Additionally, the expressions of eccDNA PAFAH1B3, mRNA PAFAH1B3, and epithelial–mesenchymal transition (EMT)-related markers were determined using RT-PCR and WB. A xenograft tumor model was established to explore the function of PAFAH1B3 in vivo, and EMT-related markers were detected using RT-PCR and IHC analyses. The abundance of eccDNA PAFAH1B3 was significantly increased in HCC cell lines after transfection with eccDNA PAFAH1B3, and promoted the proliferation, migration, and invasion of liver cells while inhibiting apoptosis. The levels of mRNA PAFAH1B3 were also upregulated. Furthermore, intratumoral injection of PAFAH1B3 inhibitor suppressed tumor growth, and PAFAH1B3 knockdown increased and decreased the levels of the E-cadherin and N-cadherin, respectively. Our study findings reveal that eccDNA PAFAH1B3 may promote the occurrence and development of HCC by enhancing the expression of PAFAH1B3 and regulating EMT. Full article

Objectives: To investigate the clinical diagnostic and prognostic value of extrachromosomal circular DNA (eccDNA) in breast cancer, eccDNA profiles were constructed for 81 breast cancer tumor tissues and 33 adjacent non-tumor tissues. Methods: The distribution characteristics of eccDNA across functional genomic elements and repetitive sequences were systematically analyzed. Furthermore, a diagnostic model for differentiating malignant and normal breast tissues, as well as a prognostic prediction model, was developed using a random forest algorithm. Results: EccDNA in breast cancer tissues harbor a higher proportion of functional elements and repetitive sequences, with their annotated genes significantly enriched in tumor- and immune-related pathways. However, no significant differences in eccDNA features were observed across breast cancer subtypes or pathological stages. In the validation cohort, the eccDNA-based diagnostic model achieved an AUC of 0.83, with repetitive elements and enhancer-associated features contributing the most to diagnostic performance. The prognostic model achieved an AUC of 0.78, with repetitive element annotations also showing strong prognostic relevance. Conclusions: These findings highlight the promising potential of eccDNA in the development of precision diagnostics and prognostic systems for breast cancer. Full article

Yunong Black (YN) pigs and Yunong Black × Landrace (YL) hybrid pigs exhibit significant differences in meat quality characteristics. Studies have suggested that extrachromosomal circular DNA (eccDNA) may play a regulatory role in muscle development. In order to study the differences in eccDNA between two groups with different meat quality traits and their potential biological significance, this study used the Circle-seq method to detect eccDNA in the longest dorsal muscle (LDM) of Yunong Black pigs (YN) (n = 3) and Yunong Black × Landrace hybrid pigs (YL) (n = 3). EccDNA-related differentially expressed genes (eccDEGs) were then analyzed in combination with RNA-seq to explore the mechanisms by which eccDNA affects meat quality. The results showed that 1325 and 1304 differentially expressed eccDNAs were identified in the YN and YL groups, varying in size and distributed across multiple genomic functional regions. These eccDNAs were also annotated according to several protein-coding genes. Combined analysis with RNA-seq results revealed 19 and 27 eccDEGs in the YN and YL groups. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis enriched many lipid-related pathways, such as chemokine signals and ADP metabolic processes. By constructing a regulatory network, several potential regulatory networks that might be related to pork quality, for example, ecc_sus_8665/ssc-miR-212/ADAMTS16, were identified. In summary, we identified several potential eccDNAs that may regulate pig muscle, offering insights into the regulation of pig muscle traits for breeding. Full article

Background: Cisplatin resistance is a major cause of tumor recurrence and mortality in high-grade serous ovarian cancer (HGSOC). Extrachromosomal circular DNA (eccDNA) has emerged as a critical factor in tumor evolution and drug resistance. However, the specific contribution of eccDNA to cisplatin resistance in HGSOC remains unclear. Methods: We performed whole-genome sequencing, Circle-Seq, and RNA-Seq in four pairs of primary and cisplatin-resistant (cisR) HGSOC cell lines to characterize genome-wide eccDNA distribution and features. Functional enrichment analyses were subsequently conducted on differentially expressed eccDNA-related genes. Results: In the SKOV3 cisR cell line, we identified a large extrachromosomal circular DNA (ecDNA) carrying the HIF1A gene, which regulates DNA repair, drug efflux, and epithelial–mesenchymal transition, contributing to cisplatin resistance. Using Circle-Seq, we detected a total of 161,062 eccDNAs, most of which were less than 1000 bp and distributed across all chromosomes. Notably, the number of eccDNAs on chromosome 21 differed significantly between the primary and cisR cell lines. Additionally, eccDNAs were predominantly located in non-coding repetitive elements. Functional analysis of eccDNA-related differentially expressed genes revealed that, compared to primary cell lines, cisR cell lines were associated with mitotic spindle assembly, regulation of vascular permeability, and cell differentiation. eccDNA-related genes involved in these pathways include MISP, WIPF1, RHOD, KRT80, and PLVAP. Conclusions: Our findings suggest that eccDNAs, particularly ecDNA amplifications like HIF1A, contribute significantly to cisplatin resistance mechanisms in HGSOC. These insights highlight eccDNA as a potential target for overcoming therapeutic resistance and improving treatment outcomes in ovarian cancer. Full article

Extrachromosomal circular DNAs (eccDNAs) are heterogeneous circular DNA molecules derived from genomic DNA, and believed to be involved in intercellular communication and in natural biological processes. Extracellular vesicles (EVs) are membrane-bound particles released from all cells, and have been shown to contain various classes of nucleic acids. EVs can play a role in intercellular communication and may be used as biomarkers. This constitutes the first study to demonstrate that EVs derived from healthy human dermal fibroblasts carry eccDNA. eccDNA from EVs and their corresponding donor cells were isolated and sequenced on the Oxford Nanopore MinIon platform, followed by the identification of potential eccDNAs through four different bioinformatic pipelines, namely ecc_Finder, cyrcular-calling, CReSIL, and Flec. Our main findings demonstrate that EVs derived from human dermal fibroblasts carry eccDNA; there is variability in the number of eccDNAs identified in the same sample through different pipelines; and there is variability in the identified eccDNAs across biological replicates. Additionally, eccDNAs characterized in this research had (a) sequences as small as 306 base pairs and as large as 28,958 base pairs across all samples, (b) uneven chromosomal distribution, and (c) an average of 49.7% of the identified eccDNAs harboring gene fragments. Future implications for this novel research include using this framework method to elucidate factors and conditions that may influence the skin aging process and related biogenesis in human dermal cells. Full article

Extrachromosomal circular DNAs (eccDNAs) has been found to be widespread and functional in various organisms. However, comparative analyses of pre- and post-infection of virus are rarely known. Herein, we investigated the changes in expression patterns of eccDNA following infection with Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) and explore the role of eccDNA in viral infection. Circle-seq was used to analyze eccDNAs in the midgut of BmCPV-infected and BmCPV-uninfected silkworms. A total of 5508 eccDNAs were identified, with sizes varying from 72 bp to 17 kb. Most of eccDNAs are between 100 to 1000 bp in size. EccDNA abundance in BmCPV-infected silkworms was significantly higher than in BmCPV-uninfected silkworms. GO and KEGG analysis of genes carried by eccDNAs reveals that most are involved in microtubule motor activity, phosphatidic acid binding, cAMP signaling pathway, and pancreatic secretion signaling pathways. Several eccDNAs contain sequences of the transcription factor SOX6, sem-2, sp8b, or Foxa2. Association analysis of eccDNA-mRNA/miRNA/circRNA revealed that some highly expressed genes are transcribed from relevant sequences of eccDNA and the transcription of protein coding genes influenced the frequency of eccDNA. BmCPV infection resulted in changes in the expression levels of six miRNAs, but no known miRNAs with altered expression levels due to changes in eccDNA abundance were identified. Moreover, it was found that 1287 and 924 sequences representing back-spliced junctions of circRNAs were shared by the junctions of eccDNAs in the BmCPV-infected and uninfected silkworms, respectively, and some eccDNAs loci were shared by circRNAs on Chromosomes 2, 7, 11, 14, and 24, suggesting some eccDNAs may exert its function by being transcribed into circRNAs. These findings suggest that BmCPV infection alter the expression pattern of eccDNAs, leading to changes in RNA transcription levels, which may play roles in regulating BmCPV replication. In the future, further experiments are needed to verify the association between eccDNA-mRNA/miRNA/circRNA and its function in BmCPV infection. Full article

Plant genomes possess numerous transposable element (TE) insertions that have occurred during evolution. Most TEs are silenced or diverged; therefore, they lose their ability to encode proteins and are transposed in the genome. Knowledge of active plant TEs and TE-encoded proteins essential for transposition and evasion of plant cell transposon silencing mechanisms remains limited. This study investigated active long terminal repeat (LTR) retrotransposons (RTEs) in sunflowers (Helianthus annuus), revealing heterogeneous and phylogenetically distinct RTEs triggered by epigenetic changes and heat stress. Many of these RTEs belong to three distinct groups within the Tekay clade, showing significant variations in chromosomal insertion distribution. Through protein analysis of these active RTEs, it was found that Athila RTEs and Tekay group 2 elements possess additional open reading frames (aORFs). The aORF-encoded proteins feature a transposase domain, a transmembrane domain, and nuclear localization signals. The aORF proteins of the Tekay subgroup exhibited remarkable conservation among over 500 Tekay members, suggesting their functional importance in RTE mobility. The predicted 3D structure of the sunflower Tekay aORF protein showed significant homology with Tekay proteins in rice, maize, and sorghum. Additionally, the structural features of aORF proteins resemble those of plant DRBM-containing proteins, suggesting their potential role in RNA-silencing modulation. These findings offer insights into the diversity and activity of sunflower RTEs, emphasizing the conservation and structural characteristics of aORF-encoded proteins. Full article

Multipartite genomes are thought to confer evolutionary advantages to bacteria by providing greater metabolic flexibility in fluctuating environments and enabling rapid adaptation to new ecological niches and stress conditions. This genome architecture is commonly found in plant symbionts, including nitrogen-fixing rhizobia, such as Rhizobium leguminosarum bv. trifolii TA1 (RtTA1), whose genome comprises a chromosome and four extrachromosomal replicons (ECRs). In this study, the transcriptomic responses of RtTA1 to partial nutrient limitation and low acidic pH were analyzed using high-throughput RNA sequencing. RtTA1 growth under these conditions resulted in the differential expression of 1035 to 1700 genes (DEGs), which were assigned to functional categories primarily related to amino acid and carbohydrate metabolism, ribosome and cell envelope biogenesis, signal transduction, and transcription. These results highlight the complexity of the bacterial response to stress. Notably, the distribution of DEGs among the replicons indicated that ECRs played a significant role in the stress response. The transcriptomic data align with the Rhizobium pangenome analysis, which revealed an over-representation of functional categories related to transport, metabolism, and regulatory functions on ECRs. These findings confirm that ECRs contribute substantially to the ability of rhizobia to adapt to challenging environmental conditions. Full article

Polar habitats offer excellent sites to isolate unique bacterial strains due to their diverse physical, geochemical, and biological factors. We hypothesize that the unique environmental conditions of polar regions select for distinct strains of lactic acid bacteria (LAB) with novel biochemical properties. In this study, we characterized ten strains of psychrotrophic LAB isolated from hitherto poorly described sources—High Arctic and maritime Antarctic soils and soil-like materials, including ornithogenic soils, cryoconites, elephant seal colonies, and postglacial moraines. We evaluated the physiological and biochemical properties of the isolates. Based on 16S rRNA and housekeeping genes, the four LAB strains were assigned to three Carnobacterium species: C. alterfunditum, C. maltaromaticum, and C. jeotgali. The remaining strains may represent three new species of the Carnobacterium genus. All isolates were neutrophilic and halophilic psychrotrophs capable of fermenting various carbohydrates, organic acids, and alcohols. The identified metabolic properties of the isolated Carnobacterium strains suggest possible syntrophic interactions with other microorganisms in polar habitats. Some showed antimicrobial activity against food pathogens such as Listeria monocytogenes and human pathogens like Staphylococcus spp. Several isolates exhibited unique metabolic traits with potential biotechnological applications that could be more effectively exploited under less stringent technological conditions compared to thermophilic LAB strains, such as lower temperatures and reduced nutrient concentrations. Analysis of extrachromosomal genetic elements revealed 13 plasmids ranging from 4.5 to 79.5 kb in five isolates, featuring unique genetic structures and high levels of previously uncharacterized genes. This work is the first comprehensive study of the biochemical properties of both known and new Carnobacterium species and enhances our understanding of bacterial communities in harsh and highly selective polar soil ecosystems. Full article

Slimming grass carp is a commercial variety with good body form and meat quality, which is cultured by starving common grass carp in a clean flowing water environment. Compared to common grass carp, slimming grass carp has a far higher economic value. Until now, no molecular study has concentrated on the regulation mechanism of the muscle characteristics of slimming grass carp. This study first reported the gene expression profile of the muscle characteristics of slimming grass carp based on the level of extrachromosomal circular DNAs (eccDNAs). EccDNAs are double-stranded circular DNAs derived from genomic DNAs and play crucial roles in the functional regulation of a wide range of biological processes, none of which have been shown to occur in fish. Here, muscle eccDNAs from slimming grass carp and common grass carp were both generally sequenced, and the information, as well as the expression profile of eccDNAs, were compared and analysed. The findings reveal that 82,238 and 25,857 eccDNAs were detected from slimming grass carp and common grass carp, respectively. The length distribution of eccDNAs was in the range of 1~1000 bp, with two peaks at about 200 bp and 400 bp. When the expression profiles of eccDNAs between slimming grass carp and common grass carp were compared, 3523 up-regulated and 175 down-regulated eccDNAs were found. Enrichment analysis showed that these eccDNA genes were correlated with cellular structure and response, cell immunology, enzyme activity, etc. Certain differentially expressed eccDNAs involved in muscle characteristics were detected, which include myosin heavy chain, myosin light chain, muscle segment homeobox C, calsequestrin, calmodulin, etc., among which the majority of genes were linked to muscle structure and contraction. This indicates that during the process of cultivating from common grass carp to slimming grass carp, the treatment primarily affected muscle structure and contraction, making the meat quality of slimming grass carp different from that of common grass carp. This result provides molecular evidence and new insights by which to elucidate the regulating mechanism of muscle phenotypic characterisation in slimming grass carp and other fish. Full article

Extrachromosomal circular DNA (eccDNA) is a form of a circular double-stranded DNA that exists independently of conventional chromosomes. eccDNA exhibits a broad and random distribution across eukaryotic cells and has been associated with tumor-related properties due to its ability to harbor the complete gene information of oncogenes. The complex and multifaceted mechanisms underlying eccDNA formation include pathways such as DNA damage repair, breakage–fusion–bridge (BFB) mechanisms, chromothripsis, and cell apoptosis. Of note, eccDNA plays a pivotal role in tumor development, genetic heterogeneity, and therapeutic resistance. The high copy number and transcriptional activity of oncogenes carried by eccDNA contribute to the accelerated growth of tumors. Notably, the amplification of oncogenes on eccDNA is implicated in the malignant progression of cancer cells. The improvement of high-throughput sequencing techniques has greatly enhanced our knowledge of eccDNA by allowing for a detailed examination of its genetic structures and functions. However, we still lack a comprehensive and efficient annotation for eccDNA, while challenges persist in the study and understanding of the functional role of eccDNA, emphasizing the need for the development of robust methodologies. The potential clinical applications of eccDNA, such as its role as a measurable biomarker or therapeutic target in diseases, particularly within the spectrum of human malignancies, is a promising field for future research. In conclusion, eccDNA represents a quite dynamic and multifunctional genetic entity with far-reaching implications in cancer pathogenesis and beyond. Further research is essential to unravel the molecular pathways of eccDNA formation, elucidate its functional roles, and explore its clinical applications. Addressing these aspects is crucial for advancing our understanding of genomic instability and developing novel strategies for tailored therapeutics, especially in cancer. Full article

Extrachromosomal circular DNA (eccDNA), a double-stranded circular DNA molecule found in multiple organisms, has garnered an increasing amount of attention in recent years due to its close association with the initiation, malignant progression, and heterogeneous evolution of cancer. The presence of eccDNA in serum assists in non-invasive tumor diagnosis as a biomarker that can be assessed via liquid biopsies. Furthermore, the specific expression patterns of eccDNA provide new insights into personalized cancer therapy. EccDNA plays a pivotal role in tumorigenesis, development, diagnosis, and treatment. In this review, we comprehensively outline the research trajectory of eccDNA, discuss its role as a diagnostic and prognostic biomarker, and elucidate its regulatory mechanisms in cancer. In particular, we emphasize the potential application value of eccDNA in cancer diagnosis and treatment and anticipate the development of novel tumor diagnosis strategies based on serum eccDNA in the future. Full article

Inflammatory bowel disease (IBD) comprising ulcerative colitis and Crohn’s disease is a chronic immune-mediated disease which affects the gastrointestinal tract with a relapsing and remitting course, causing lifelong morbidity. IBD pathogenesis is determined by multiple factors including genetics, immune and microbial factors, and environmental factors. Although therapy options are expanding, remission rates are unsatisfiable, and together with the disease course, response to therapy remains unpredictable. Therefore, the identification of biomarkers that are predictive for the disease course and response to therapy is a significant challenge. Extrachromosomal circular DNA (eccDNA) fragments exist in all tissue tested so far. These fragments, ranging in length from a few hundreds of base pairs to mega base pairs, have recently gained more interest due to technological advances. Until now, eccDNA has mainly been studied in relation to cancer due to its ability to act as an amplification site for oncogenes and drug resistance genes. However, eccDNA could also play an important role in inflammation, expressed both locally in the- involved tissue and at distant sites. Here, we review the current evidence on the molecular mechanisms of eccDNA and its role in inflammation and IBD. Additionally, the potential of eccDNA as a tissue or plasma marker for disease severity and/or response to therapy is evaluated. Full article

Cell-free extrachromosomal circular DNA (cf-eccDNA) has been proposed as a promising early biomarker for disease diagnosis, progression and drug response. Its established biomarker features are changes in the number and length distribution of cf-eccDNA. Another novel promising biomarker is a set of eccDNA excised from a panel of genes specific to a condition compared to a control. Deficiencies in two endonucleases that specifically target DNA, Dnase1 and Dnase1l3, are associated with systemic lupus erythematosus (SLE). To study the genic eccDNA profiles in the case of their deficiencies, we mapped sequenced eccDNA data from plasma, liver and buffy coat from Dnase1 and Dnase1l3 knockouts (KOs), and wild type controls in mouse. Next, we performed an eccDNA differential analysis between KO and control groups using our DifCir algorithm. We found a specific genic cf-eccDNA fingerprint of the Dnase1l3 group compared to the wild type controls involving 131 genes; 26% of them were associated with human chromosomal fragile sites (CFSs) and with a statistically significant enrichment of CFS-associated genes. We found six genes in common with the genic cf-eccDNA profile of SLE patients with DNASE1L3 deficiency, namely Rorb, Mvb12b, Osbpl10, Fto, Tnik and Arhgap10; all of them were specific and present in all human plasma samples, and none of them were associated with CFSs. A not so distinctive genic cf-eccDNA difference involving only seven genes was observed in the case of the Dnase1 group compared to the wild type. In tissue—liver and buffy coat—we did not detect the same genic eccDNA difference observed in the plasma samples. These results point to a specific role of a set of genic eccDNA in plasma from DNase KOs, as well as a relation with CFS genes, confirming the promise of the genic cf-eccDNA in studying diseases and the need for further research on the relationship between eccDNA and CFSs. Full article

Bacterial diversity analyses often suffer from a bias due to sampling only from a limited number of hosts or narrow geographic locations. This was the case for the phytopathogenic species Dickeya solani, whose members were mainly isolated from a few hosts–potato and ornamentals–and from the same geographical area–Europe and Israel, which are connected by seed trade. Most D. solani members were clonal with the notable exception of the potato isolate RNS05.1.2A and two related strains that are clearly distinct from other D. solani genomes. To investigate if D. solani genomic diversity might be broadened by analysis of strains isolated from other environments, we analysed new strains isolated from ornamentals and from river water as well as strain CFBP 5647 isolated from tomato in the Caribbean island Guadeloupe. While water strains were clonal to RNS05.1.2A, the Caribbean tomato strain formed a third clade. The genomes of the three clades are highly syntenic; they shared almost 3900 protein families, and clade-specific genes were mainly included in genomic islands of extrachromosomal origin. Our study thus revealed both broader D. solani diversity with the characterisation of a third clade isolated in Latin America and a very high genomic conservation between clade members. Full article