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CCRR: a user-friendly platform for analyzing complex chromosomal rearrangements in tumors.

SUMMARY: Complex chromosomal rearrangements in tumors involve intricate genomic alterations that significantly affect gene function and contribute to cancer development. Identifying these events is crucial for cancer research but is often challenging due to the complexity and limitations of existing tools. We developed the Complex Chromosomal Rearrangements Resolver (CCRR), a comprehensive, reproducible, and user-friendly platform for analyzing complex rearrangements in tumors. CCRR integrates multiple SV and CNV detection tools within a Docker container environment, simplifying installation and configuration. It can be easily deployed, automating the execution and merging of results, providing high-confidence consensus SV and CNV calls, allowing researchers to efficiently analyze complex chromosomal rearrangements in tumors without extensive bioinformatics expertise. CCRR also includes a web server for one-click analysis and customized visualization. AVAILABILITY AND IMPLEMENTATION: The CCRR platform is freely available at https://www.ccrr.life. Source code and executables can be accessed at https://github.com/laslk/CCRR. An archived version is available at Zenodo: https://doi.org/10.5281/zenodo.15386513.

Software

Global genomic population structure of wild and cultivated oat reveals signatures of chromosome rearrangements.

The genus Avena consists of approximately 30 wild and cultivated oat species. Cultivated oat is an important food crop, yet the broader genetic diversity within the Avena gene pool remains underexplored and underexploited. Here, we characterize over 9000 wild and cultivated hexaploid oat accessions of global origin using genotyping-by-sequencing and explore population structure using multidimensional scaling and population-based clustering methods. We also conduct analyses to reveal chromosome regions associated with local adaptation, sometimes resulting from large-scale chromosome rearrangements. We report four distinct genetic populations within the wild species A. sterilis, a distinct population of cultivated A. byzantina, and multiple populations within cultivated A. sativa. Some chromosome regions associated with local adaptation are also associated with confirmed structural rearrangements on chromosomes 1A, 1C, 3C, 4C, and 7D. This work provides evidence suggesting multiple polyploid origins, multiple domestications, and/or reproductive barriers amongst Avena populations caused by differential chromosome structure.

Avena

Chromosome engineering to correct a complex rearrangement on Chromosome 8 reveals the effects of 8p syndrome on gene expression and neural differentiation.

Chromosomal rearrangements on the short arm of Chromosome 8 cause 8p syndrome, a rare developmental disorder characterized by neurodevelopmental delays, epilepsy, and cardiac abnormalities. Although significant progress has been made in managing the symptoms of 8p syndrome and other conditions caused by large-scale chromosomal aneuploidies, no therapeutic approach has yet been demonstrated to target the underlying disease-causing chromosome. Here, we establish a two-step approach to eliminate the abnormal copy of Chromosome 8 and restore euploidy in cells derived from an individual with a complex rearrangement of Chromosome 8p. Transcriptomic analysis revealed 361 differentially expressed genes between the proband and the euploid revertant, highlighting genes both within and outside the 8p region that may contribute to 8p syndrome pathology. Furthermore, we demonstrate that the proband exhibits a significant defect in neural differentiation that could be partially rescued by treatment with small-molecule inhibitors of cell death. Our work demonstrates the feasibility of using chromosome engineering to correct complex aneuploidies in vitro and establishes a platform to further dissect the pathophysiology of 8p syndrome and other conditions caused by chromosomal rearrangements.

Humans

CRISPR-Engineered CAR-T Cell Therapy for Epstein-Barr Virus-Associated Nasopharyngeal Carcinoma: A Review of Emerging Therapeutic Prospects.

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) remains a clinically challenging malignancy, particularly in recurrent or metastatic disease where durable responses to chemoradiotherapy and immune checkpoint blockade are limited. The viral aetiology of NPC provides a strong biological rationale for immune-based treatment; however, translation of chimaeric antigen receptor (CAR) T-cell therapy into this solid tumour setting is constrained by poor tumour trafficking, antigen heterogeneity, limited surface accessibility of EBV latent antigens, T-cell exhaustion, and an immunosuppressive tumour microenvironment. This review critically evaluates the emerging therapeutic prospects of CRISPR-engineered CAR-T cell therapy for EBV-associated NPC. It synthesises evidence on EBV latency biology, NPC immune evasion, solid-tumour CAR-T limitations, and genome-engineering strategies including conventional CRISPR-Cas9, base editing, prime editing, and double-strand-break-sparing targeted integration. Particular attention is given to genotoxicity, chromosomal rearrangements, chromosome loss, bystander and off-target editing, manufacturing heterogeneity, and the regulatory and biological barriers that currently separate technical feasibility from NPC-specific clinical implementation. Available clinical evidence from checkpoint blockade, EBV-specific adoptive T-cell therapy, base-edited CAR-T cells in haematologic malignancy, and early CRISPR-edited T-cell trials supports the feasibility of immune and genetic redirection but does not establish efficacy of a clinically validated CRISPR-engineered CAR-T platform for NPC. Future development should prioritise surface-accessible antigen validation, fit-for-purpose selection of editing technology, genomic safety, scalable manufacturing, and biomarker-driven early-phase trials.

Humans

Expansion of satellite DNAs derived from transposable elements in beetles with reduced diploid numbers.

Repetitive DNA sequences are ubiquitous in eukaryotic genomes, significantly influencing their structure, function, and evolution. They can facilitate genomic rearrangements, contributing to chromosomal and genomic diversity. Chrysomelidae (Coleoptera) beetles are known for their highly diverse karyotypes and heterochromatin distribution. In this study, we advanced the understanding of the intricate relationship between satellite DNA-like sequences (named here solely as satDNA) and genome organization/reshuffling using three species of Eumolpinae chrysomelids. We investigated the satellitomes of three species with divergent karyotypes that had undergone independent chromosomal fusions: Colaspis laeta (2n = 22, Xyp), with a conserved karyotype; Endocephalus bigatus (2n = 10, neo-XY); and Iphimeis dives (2n = 14, neo-XY). Our comparative analysis revealed highly divergent patterns of satDNA origin, organization, and evolution. In species with reduced chromosome numbers and neo-sex chromosomes, we observed a high abundance of transposable element-related (TE-related) satDNAs. In Colaspis laeta, the sex chromosomes (Xyp) showed an advanced level of differentiation. However, in the species with a reduction in diploid number, such a level of differential enrichment of repetitive DNAs was not observed in the sex chromosomes, indicating an early stage of differentiation. Our findings support the hypothesis that chromosomal rearrangements and reorganization of repetitive DNA sequences are connected, with extensive reshuffling observed in species with reduced diploid numbers. Moreover, the data reinforce the involvement of TEs in satDNA origin, which could spread widely throughout the genome, including euchromatic areas. This study provides new insights into the evolutionary dynamics of repetitive DNAs in non-model species, emphasizing the impact of chromosomal rearrangements on genome architecture and evolution.

Animals

Haplotype-resolved reconstruction and functional interrogation of cancer karyotypes.

Complex karyotype changes are widespread in cancer genomes. A major gap in cancer genome characterization is the resolution of rearranged chromosomes with chromosome-length continuity. Here, we describe a two-tiered approach to determine the segmental composition of rearranged chromosomes with haplotype resolution. First, we present refLinker, a bioinformatic method for robust determination of chromosomal haplotypes using cancer Hi-C data. By contrast with existing methods, refLinker is insensitive to the presence of large-scale DNA deletions, duplications, and high-level amplification in cancer genomes. Second, we demonstrate a computational strategy to determine the segmental structure of rearranged chromosomes using haplotype-specific Hi-C contacts. We apply these methods to breast cancer genomes and provide direct evidence for long-range transcriptional changes associated with rearrangements of the inactive X chromosome. Together, these results highlight refLinker's broad utility for studying the functional consequences of chromosomal rearrangements.

Humans

L1 insertion intermediates recombine with one another or with DNA breaks to form genome rearrangements.

LINE-1 retrotransposition is common in human cancers and rearrangements at insertion sites can contribute to cancer-driving oncogene amplifications and promote genome instability. However, the mechanisms underlying rearrangements of L1 retrotransposition intermediates are poorly understood. To address this gap, we developed GFP-based recombination reporter assays to study the formation of L1 retrotransposition-mediated rearrangements. Using these reporters combined with long-read sequencing approaches, we find that L1 retrotransposition intermediates can recombine with distal DNA breaks to generate chromosomal rearrangements. We also find that two distinct L1 insertion intermediates can recombine with each other to generate chromosomal rearrangements. Both types of rearrangements depend on L1-encoded ORF2p endonuclease and reverse transcriptase activities. Using these reporters, we discover that L1 retrotransposition-mediated rearrangements are robustly induced when the recombining sequences share homology and that their formation requires the homologous recombination factor BRCA1. Given the repetitive nature of our genome, these findings highlight the risk of L1 insertion intermediates becoming substrates for aberrant recombination and promoting genome instability.

L1 retrotransposons

Homologous recombination defects and how they affect replication fork maintenance.

Homologous recombination (HR) repairs DNA double strand breaks (DSBs) and stabilizes replication forks (RFs). RAD51 is the recombinase for the HR pathway. To preserve genomic integrity, RAD51 forms a filament on the 3' end of a DSB and on a single-stranded DNA (ssDNA) gap. But unregulated HR results in undesirable chromosomal rearrangements. This review describes the multiple mechanisms that regulate HR with a focus on those mechanisms that promote and contain RAD51 filaments to limit chromosomal rearrangements. If any of these pathways break down and HR becomes unregulated then disease, primarily cancer, can result.

RAD51 filaments

LINE-1 insertion intermediates recombine with one another or with DNA breaks to form genome rearrangements.

LINE-1 (L1) retrotransposition is common in human cancers and rearrangements at insertion sites can contribute to cancer-driving oncogene amplifications and promote genome instability. However, the mechanisms underlying rearrangements of L1 retrotransposition intermediates are poorly understood. To address this gap, we developed GFP-based recombination reporter assays to study the formation of L1 retrotransposition-mediated rearrangements. Using these reporters combined with long-read sequencing, we find that L1 retrotransposition cDNA intermediates can recombine with distal DNA breaks to generate chromosomal rearrangements. We also find that two independent L1 insertion cDNA intermediates on distinct genomic loci can recombine with each other to generate chromosomal rearrangements. Both types of rearrangements depend on L1-encoded ORF2p endonuclease and reverse transcriptase activities. Using these reporters, we discover that L1 retrotransposition-mediated rearrangements are robustly induced when the recombining sequences share extensive homology and that their formation requires the homologous recombination factor BRCA1. In contrast, we find L1 retrotransposition-mediated rearrangements are suppressed by the mismatch repair factor MSH2 when the recombining sequences contain mismatches. Given the repetitive nature of our genome, these findings highlight the risk of L1 insertion intermediates becoming substrates for aberrant recombination and promoting genome instability.

Long Interspersed Nucleotide Elements

Genome evolution of the ancient hexaploid Platanus × acerifolia (London planetree).

Whole-genome duplication (WGD; i.e., polyploidy) and chromosomal rearrangement (i.e., genome shuffling) significantly influence genome structure and organization. Many polyploids show extensive genome shuffling relative to their pre-WGD ancestors. No reference genome is currently available for Platanaceae (Proteales), one of the sister groups to the core eudicots. Moreover, Platanus × acerifolia (London planetree; Platanaceae) is a widely used street tree. Given the pivotal phylogenetic position of Platanus and its 2-y flowering transition, understanding its flowering-time regulatory mechanism has significant evolutionary implications; however, the impact of Platanus genome evolution on flowering-time genes remains unknown. Here, we assembled a high-quality, chromosome-level reference genome for P. × acerifolia using a phylogeny-based subgenome phasing method. Comparative genomic analyses revealed that P. × acerifolia (2n = 42) is an ancient hexaploid with three subgenomes resulting from two sequential WGD events; Platanus does not seem to share any WGD with other Proteales or with core eudicots. Each P. × acerifolia subgenome is highly similar in structure and content to the reconstructed pre-WGD ancestral eudicot genome without chromosomal rearrangements. The P. × acerifolia genome exhibits karyotypic stasis and gene sub-/neo-functionalization and lacks subgenome dominance. The copy number of flowering-time genes in P. × acerifolia has undergone an expansion compared to other noncore eudicots, mainly via the WGD events. Sub-/neo-functionalization of duplicated genes provided the genetic basis underlying the unique flowering-time regulation in P. × acerifolia. The P. × acerifolia reference genome will greatly expand understanding of the evolution of genome organization, genetic diversity, and flowering-time regulation in angiosperms.

Polyploidy

Large Haplotypes Linked to Climate and Life History Variation in Divergent Lineages of Atlantic Salmon (Salmo salar).

Advances in sequencing are revealing that linked genomic architectures, enabling the evolution of co-adapted alleles at multiple loci, often shape complex phenotypes. Several recent studies have identified such architectures (e.g., chromosomal rearrangements and supergenes) contributing to adaptation or divergence across diverse species, from plants to mammals. Specifically, within Atlantic salmon (Salmo salar ), genomic studies are revealing large haplotypes and structural variants that may underpin local adaptation in the species. Using data from > 4000 individuals from 134 locations spanning the North Atlantic Ocean, we identify a large (~3 Mbp) genomic region on Ssa18 showing patterns of differentiation and linkage disequilibrium (LD) indicative of a large haplotype block containing three divergent haplotypes (herein A, B and C haplotypes). In Europe, haplotypes A and B were common, whereas A and C were more common within North America, suggesting a shared 'ancestral' A haplotype, with different continent-specific alternative haplotypes. Data support independent origins of divergent haplotypes in each continent, as well as signals of trans-oceanic introgression of haplotypes. Haplotype frequency is strongly associated with latitude, climate and life history (smolt age); however, the strength and direction of these relationships vary across continents. Overall, our analyses were consistent with other studies that identify chromosomal rearrangements; however, long-read sequence data did not find evidence of a structural variant, and instead an ancestral fusion may explain the formation and maintenance of the observed haplotypes. Our study contributes to ongoing efforts to understand the evolutionary role of linked genomic architecture in Atlantic salmon and its significance in salmonid diversification.

Climate Change

Chromosome painting in plants: history and future perspectives.

Chromosome painting was developed in mammalian species nearly four decades ago and rapidly became a powerful tool for chromosome identification, comparative cytogenetics, and evolutionary genome analysis. Comparative chromosome painting among diverse mammals generated much of the foundational knowledge of chromosome structure, chromosomal rearrangements, and karyotype evolution before the advent of whole-genome sequencing. Although chromosome painting was first demonstrated in plants in 2001, its applications remained largely restricted to a few plant lineages until the development of oligonucleotide (oligo)-based chromosome painting in 2015. During the last decade, oligo-based chromosome painting has transformed plant cytogenetics, enabling many investigations that were previously impossible. These studies have provided new insights into meiotic chromosome pairing, crossover formation, chromosome fusion, karyotype stability, and chromosome evolution across diverse plant lineages. This review summarizes the history of technological development of chromosome painting in plants, highlights major discoveries enabled by oligo-based chromosome painting, and discusses future opportunities, particularly the integration of chromosome painting with three-dimensional chromosome and genome biology.

Chromosome Painting

Structural genome variation drives adaptation of the xylose-fermenting yeast Scheffersomyces stipitis to lignocellulosic hydrolysates.

Second-generation (2G) bioethanol from lignocellulosic feedstocks is a sustainable alternative to fossil fuels. However, its production is constrained by the poor performance of industrial microbes in hydrolysates that are generated during biomass pretreatment. Scheffersomyces stipitis is a native xylose fermenting yeast and a promising platform for 2G bioethanol production, and adaptive evolution under hydrolysate stress has yielded strains with enhanced performance. However, the chromosomal basis of this adaptation is unknown. Here, we demonstrate that chromosome scale structural variation, rather than point mutations, underlies the improved phenotype of the evolved strains. By integrating long- and short-read genome sequencing, we identify two major chromosomal rearrangements in the top performing isolate: a reciprocal translocation between chromosomes 1 and 2 that disrupts the NUDIX hydrolase gene YSA1, and the formation of a mitotically stable 175 kb minichromosome derived from chromosome 5. Functional analyses show that disruption of YSA1 enhances xylose utilisation and ethanol yield, while the minichromosome contributes to improved performance in hydrolysate conditions. These findings provide direct evidence that balanced rearrangements and minichromosome formation can be selected during prolonged stress and can generate adaptive phenotypes. Taken together, our study establishes genome reorganisation as a key driver of adaptation in S. stipitis.

Xylose

Unequally Abundant Chromosomes and Unusual Collections of Transferred Sequences Characterize Mitochondrial Genomes of Gastrodia (Orchidaceae), One of the Largest Mycoheterotrophic Plant Genera.

The mystery of genomic alternations in heterotrophic plants is among the most intriguing in evolutionary biology. Compared to plastid genomes (plastomes) with parallel size reduction and gene loss, mitochondrial genome (mitogenome) variation in heterotrophic plants remains underexplored in many aspects. To further unravel the evolutionary outcomes of heterotrophy, we present a comparative mitogenomic study with 13 de novo assemblies of Gastrodia (Orchidaceae), one of the largest fully mycoheterotrophic plant genera, and its relatives. Analyzed Gastrodia mitogenomes range from 0.56 to 2.1 Mb, each consisting of numerous, unequally abundant chromosomes or contigs. Size variation might have evolved through chromosome rearrangements followed by stochastic loss of "dispensable" chromosomes, with deletion-biased mutations. The discovery of a hyper-abundant (∼15 times intragenomic average) chromosome in two assemblies represents the hitherto most extreme copy number variation in any mitogenomes, with similar architectures discovered in two metazoan lineages. Transferred sequence contents highlight asymmetric evolutionary consequences of heterotrophy: despite drastically reduced intracellular plastome transfers convergent across heterotrophic plants, their rarity of horizontally acquired sequences sharply contrasts parasitic plants, where massive transfers from their hosts prevail. Rates of sequence evolution are markedly elevated but not explained by copy number variation, extending prior findings of accelerated molecular evolution from parasitic to heterotrophic plants. Putative evolutionary scenarios for these mitogenomic convergence and divergence fit well with the common (e.g. plastome contraction) and specific (e.g. host identity) aspects of the two heterotrophic types. These idiosyncratic mycoheterotrophs expand known architectural variability of plant mitogenomes and provide mechanistic insights into their content and size variation.

Genome, Mitochondrial

STK11 Mutations and Deletions Define an Aggressive Molecular Subgroup of Cervical Adenocarcinoma.

Cervical adenocarcinoma accounts for 15%-20% of cervical cancers and is associated with poorer survival and reduced response to screening and immunotherapy compared with squamous cell carcinoma (SCC). The genomic drivers underlying this molecular subgroup remain incompletely characterized. Whole-exome sequencing was performed on 302 invasive cervical cancers from Guatemala and Venezuela. Structural variation analysis was conducted using SNP-array and whole-genome sequencing data. Findings were replicated in more than 4600 additional cervical cancer samples from TCGA, AACR Project GENIE, MSKCC, and Caris datasets. TP53 mutations were more frequent in adenocarcinoma than SCC, particularly in HPV-negative tumors. STK11 alterations, including mutations and focal deletions, were significantly enriched in HPV-positive adenocarcinomas compared with SCC and affected 23% of adenocarcinomas overall. Whole-genome analyses identified recurrent focal deletions, inversions, chromosomal rearrangements, and breakage-fusion-bridge events involving chromosome 19p and STK11 that were not detected by exome sequencing alone. STK11 alterations were associated with younger age at diagnosis, poorer overall survival, and inferior outcomes following immune checkpoint inhibitor (ICI) therapy. STK11 alterations significantly co-occurred with YAP1 amplification but were largely mutually exclusive with PIK3CA mutation. Cervical adenocarcinomas also demonstrated significantly lower CD274 (PD-L1) expression than SCC. STK11 alterations define a distinct molecular subgroup of cervical adenocarcinoma characterized by structural disruption of chromosome 19p, younger age at onset, and poorer clinical outcomes. These findings have implications for molecular classification and future targeted therapeutic approaches in cervical cancer.

Humans

MetaChrome: An Open-Source, User-Friendly Tool for Automated Metaphase Chromosome Analysis.

DNA Fluorescence In Situ Hybridization (FISH) is an essential technique to study chromosome biology and genetics, enabling precise visualization of specific genomic loci to study structural abnormalities, gene mapping, and chromosomal rearrangements. High-Throughput Imaging (HTI) can automate the analysis of DNA-FISH chromosome images, but the accurate and automated segmentation of mitotic chromosomes and simultaneous colocalization of FISH signals remains a challenge. While several commercial automated karyotyping tools partially solve these issues, open-source software that effectively combines robust chromosome segmentation with comprehensive colocalization analysis capabilities remains necessary. To address this unmet need, we developed MetaChrome, an open-source software platform built around a graphical user interface and explicitly designed for automated metaphase chromosome analysis. MetaChrome leverages fine-tuned deep learning models to automate metaphase chromosome segmentation, together with colocalization analysis of chromosome-specific FISH probes and immunofluorescent-labeled proteins. Importantly, MetaChrome achieves enhanced segmentation accuracy compared to traditional image processing methods by adopting a Cellpose segmentation model fine-tuned with manually annotated metaphase chromosome datasets. The fine-tuned model ensures precise assignment of DNA-FISH spots to individual chromosomes in an automated manner. This facilitates rapid identification of chromosomal abnormalities, reduces human error, and advances high-throughput chromosome analysis workflows, addressing a key bottleneck in chromosome biology research.

Chromosome segmentation

The centromere landscapes of four karyotypically diverse Papaver species provide insights into chromosome evolution and speciation.

Understanding the roles played by centromeres in chromosome evolution and speciation is complicated by the fact that centromeres comprise large arrays of tandemly repeated satellite DNA, which hinders high-quality assembly. Here, we used long-read sequencing to generate nearly complete genome assemblies for four karyotypically diverse Papaver species, P. setigerum (2n = 44), P. somniferum (2n = 22), P. rhoeas (2n = 14), and P. bracteatum (2n = 14), collectively representing 45 gapless centromeres. We identified four centromere satellite (cenSat) families and experimentally validated two representatives. For the two allopolyploid genomes (P. somniferum and P. setigerum), we characterized the subgenomic distribution of each satellite and identified a "homogenizing" phase of centromere evolution in the aftermath of hybridization. An interspecies comparison of the peri-centromeric regions further revealed extensive centromere-mediated chromosome rearrangements. Taking these results together, we propose a model for studying cenSat competition after hybridization and shed further light on the complex role of the centromere in speciation.

Centromere

A translocation within the Ogataea species complex alters local subtelomeric chromatin while maintaining overall genome organization.

Eukaryotic genomic DNA is packaged in the nucleus as chromatin-a DNA-protein aggregate regulating genome function, including transcription. Chromatin is classified as either active euchromatin or silent heterochromatin, with each marked by distinct histone post-translational modifications (PTMs). Chromatin composition also mediates genome organization, including how heterochromatin aggregates at the nuclear periphery while euchromatin localizes to the nucleus center. In fungi, heterochromatic loci cluster, including independent centromere and telomere clusters that form the Rabl chromosome conformation. However, it is unknown if chromatin composition and genome organization are conserved in closely related fungi, and how these features are impacted by large-scale chromosomal rearrangements. Here, we examined differences in histone PTM deposition, gene expression, and genome organization in 2 yeast species from the order Pichiales, which diverged from the common ancestor shared with Saccharomyces cerevisiae more than 200 million years ago. We focused on Ogataea polymorpha, which is used for industrial protein production, and Ogataea haglerorum, an isolate of which harbors a translocation between chromosomes 1 and 6. We show that the enrichment of 3 activating PTMs-the trimethylation of lysine 4 of histone H3 (H3K4me3) and the acetylation of lysine 9 of histone H3 (H3K9ac) or lysine 16 of histone H4 (H4K16ac)-are similar genome-wide, yet gene orthologs have distinct chromatin and expression patterns. While both Ogataea genomes organize into a Rabl conformation, the O. haglerorum translocation alters subtelomeric chromatin composition and expression of genes affected by the translocation. Our work highlights the genome function differences that occur on a microevolutionary scale.

Genome, Fungal