Biology subjects

Shi, Q.

Publications and source records attributed to Shi, Q..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

DRED: A Comprehensive Database of Genes Related to Repeat Expansion Diseases

Expansion of tandem repeats in genes often causes severe neuromuscular diseases, such as fragile X syndrome, huntingtons disease, and spinocerebellar ataxia. However, information on genes associated with repeat expansion diseases is scattered throughout the literature, systematic prediction of potential genes that may cause diseases via repeat expansion is also lacking. Here, we develop DRED, a Database of genes related to Repeat Expansion Diseases, as a manually-curated database that covers all known 61 genes related to repeat expansion diseases reported in PubMed and OMIM, along with detailed repeat information for each gene. DRED also includes 516 genes with the potential to cause diseases via repeat expansion, which were predicted basing on their repeat composition, genetic variations, genomic features, and disease associations. Various types of information on repeat expansion diseases and their corresponding genes/repeats are presented in DRED, together with links to external resources, such as NCBI and ClinVar. DRED provides user-friendly interfaces with comprehensive functions, and can serve as a central data resource for basic research and repeat expansion disease-related medical diagnosis. DRED is freely accessible at http://omicslab.genetics.ac.cn/dred, and is frequently updated to include newly reported genes related to repeat expansion diseases.

bioinformatics↗

bioRxiv2024

Enhancer activation from transposable elements in extrachromosomal DNA

Extrachromosomal DNA (ecDNA) drives oncogene amplification and intratumoral heterogeneity in aggressive cancers. While transposable element (TE) reactivation is common in cancer, its role on ecDNA remains unexplored. Here, we map the 3D architecture of MYC-amplified ecDNA in colorectal cancer cells and identify 68 ecDNA-interacting elements (EIEs)--genomic loci enriched for TEs that are frequently integrated onto ecDNA. We focus on an L1M4a1#LINE/L1 fragment co-amplified with MYC, which functions only in the ecDNA amplified context. Using CRISPR-CATCH, CRISPR interference, and reporter assays, we confirm its presence on ecDNA, enhancer activity, and essentiality for cancer cell fitness. These findings reveal that repetitive elements can be reactivated and co-opted as functional rather than inactive sequences on ecDNA, potentially driving oncogene expression and tumor evolution. Our study uncovers a mechanism by which ecDNA harnesses repetitive elements to shape cancer phenotypes, with implications for diagnosis and therapy.

genetics↗

bioRxiv2024

Promotion of RNF168-Mediated Nucleosomal H2A Ubiquitylation by Structurally-defined K63-Polyubiquitylated Linker Histone H1

The chemical synthesis of histones with homogeneous modifications is a potent approach for quantitatively deciphering the functional crosstalk between different post-translational modifications (PTMs). Here, we developed an expedient site-specific (poly)ubiquitylation strategy (CAEPL, Cysteine-Aminoethylation coupled with Enzymatic Protein Ligation), which integrates the Cys-aminoethylation reaction with the process of ubiquitin-activating enzyme UBA1-assisted native chemical ligation. Using this strategy, we successfully prepared monoubiquitylated and K63-linked di- and tri-ubiquitylated linker histone H1.0 proteins, which were incorporated into individual chromatosomes. Quantitative biochemical analysis of different RNF168 constructs on ubiquitylated chromatosomes with different ubiquitin lengths demonstrated that K63-linked polyubiquitylated H1.0 could directly stimulate RNF168 ubiquitylation activity by enhancing the affinity between RNF168 and chromatosome. Subsequent cryo-EM structural analysis of the RNF168/UbcH5c-Ub/H1.0-K63-Ub3 chromatosome complex revealed the potential recruitment orientation between RNF168 UDM1 domain and K63-linked ubiquitin chain on H1.0. Finally, we explored the impact of H1.0 ubiquitylation on RNF168 activity in the context of asymmetric H1.0-K63-Ub3 di-nucleosome substrate, revealing a comparable stimulation effect of both the inter- and intra-nucleosomal crosstalk. Overall, our study highlights the significance of access to structurally-defined polyubiquitylated H1.0 by CAEPL strategy, enabling in-depth mechanistic investigations of in-trans PTM crosstalk between linker histone H1.0 and core histone H2A ubiquitylation.

biochemistry↗

bioRxiv2024

YTHDF2 upregulation and relocation dictate CD8 T cell polyfunctionality in tumor immunity

Epigenetic traits impact the antitumor function of CD8 T cells, yet whether and how RNA methylation programs engage in T cell immunity is poorly understood. Here we show that the N6-methyladenosine (m6A) RNA reader YTHDF2 is highly expressed in early effector or effector-like CD8 T cells and is partially distributed in the nucleus. YTHDF2 loss in T cells exacerbates tumor progression and confers unresponsiveness to PD-1 blockade in mice and humans. In addition to initiating RNA decay for mitochondrial fitness, YTHDF2 can orchestrate chromatin regulation to promote T cell polyfunctionality. YTHDF2-mediatd preservation of gene transcription arises from the interaction of YTHDF2 with IKZF1/3. Accordingly, immunotherapy-induced efficacy could be largely restored in YTHDF2-deficient T cells through combinational use of lenalidomide. Moreover, m6A recognition is fundamental for YTHDF2 translocation to the nucleus and autoregulation at the RNA level. Thus, YTHDF2 coordinates epitranscriptional and transcriptional networks to potentiate T cell immunity. HighlightsO_LIYTHDF2 expression and distribution underpin the threshold for bona fide CD8 T cell effector response C_LIO_LICanonical YTHDF2-mRNA decay pathway alleviates mitochondrial stress and CD8 T cell exhaustion C_LIO_LINuclear YTHDF2 sequesters IKZF1/3-mediated transcriptional repression to safeguard CD8 T cell polyfunctionality C_LIO_LIThe tumoricidal activity of YTHDF2-deficient CD8 T cells could be repaired through the synergy of anti-PD-1 and lenalidomide C_LI

immunology↗

bioRxiv2024

Deficiency in a special dynein DNAH12 causes male infertility by impairing DNAH1 and DNALI1 recruitment in humans and mice

Asthenoteratozoospermia, a prevalent cause of male infertility, lacks a well-defined etiology. DNAH12 is a special dynein featured by the absence of a microtubule-binding domain, however, its functions in spermatogenesis remain largely unknown. Through comprehensive genetic analyses involving whole-exome sequencing and subsequent Sanger sequencing on infertile patients and fertile controls from six distinct families, we unveiled six biallelic mutations in DNAH12 that co-segregate recessively with male infertility in the studied families. Transmission electron microscopy (TEM) revealed pronounced axonemal abnormalities, including inner dynein arms (IDAs) impairment and central pair (CP) loss in sperm flagella of the patients. Mouse models (Dnah12-/- and Dnah12mut/mut) were generated and recapitulated the reproductive defects in the patients. Noteworthy, DNAH12 deficiency did not show effects on cilium organization and function. Mechanistically, DNAH12 was confirmed to interact with two other IDA components DNALI1 and DNAH1, while disruption of DNAH12 leads to failed recruitment of DNALI1 and DNAH1 to IDAs and compromised sperm development. Furthermore, DNAH12 also interacts with radial spoke head proteins RSPH1, RSPH9, and DNAJB13 to regulate CP stability. Moreover, the infertility of Dnah12-/- mice could be overcome by intracytoplasmic sperm injection (ICSI) treatment. Collectively, DNAH12 plays a crucial role in the proper organization of axoneme in sperm flagella, but not cilia, by recruiting DNAH1 and DNALI1 in both humans and mice. These findings expand our comprehension of dynein component assembly in flagella and cilia and provide a valuable marker for genetic counseling and diagnosis of asthenoteratozoospermia in clinical practice.

genetics↗

bioRxiv2024

FAPM: Functional Annotation of Proteins using Multi-Modal Models Beyond Structural Modeling

Assigning accurate property labels to proteins, like functional terms and catalytic activity, is challenging, especially for proteins without homologs and "tail labels" with few known examples. Unlike previous methods that mainly focused on protein sequence features, we use a pretrained large natural language model to understand the semantic meaning of protein labels. Specifically, we introduce FAPM, a contrastive multi-modal model that links natural language with protein sequence language. This model combines a pretrained protein sequence model with a pretrained large language model to generate labels, such as Gene Ontology (GO) functional terms and catalytic activity predictions, in natural language. Our results show that FAPM excels in understanding protein properties, outperforming models based solely on protein sequences or structures. It achieves state-of-the-art performance on public benchmarks and in-house experimentally annotated phage proteins, which often have few known homologs. Additionally, FAPMs flexibility allows it to incorporate extra text prompts, like taxonomy information, enhancing both its predictive performance and explainability. This novel approach offers a promising alternative to current methods that rely on multiple sequence alignment for protein annotation. The online demo is at: https://huggingface.co/spaces/wenkai/FAPM_demo.

bioinformatics↗

bioRxiv2024

Accurate Assembly of Circular RNAs with TERRACE

Circular RNA (circRNA) is a class of RNA molecules that forms a closed loop with its 5 and 3 ends covalently bonded. Due to this specific structure circRNAs are more stable than linear RNAs, admit distinct biological properties and functions, and have been proven to be promising biomarkers. Circular RNAs were severely overlooked previously owing to the biases in the RNA-seq protocols and in the detection algorithms, but recently gained tremendous attentions in both aspects. However, most existing methods for assembling circRNAs heavily rely on the annotated transcriptomes, and hence exhibit unsatisfactory accuracy when a high-quality transcriptome is unavailable. Here we present TERRACE, a new algorithm for full-length assembly of circRNAs from paired-end total RNA-seq data. TERRACE uses the splice graph as the underlying data structure to organize the splicing and coverage information. We transform the problem of assembling circRNAs into finding two paths that "bridge" the three fragments in the splice graph induced by back-spliced reads. To solve this formulation, we adopted a definition for optimal bridging paths and a dynamic programming algorithm to calculate such paths, an approach that was proven useful for assembling linear RNAs. TERRACE features an efficient algorithm to detect back-spliced reads that are missed by RNA-seq aligners, contributing to its much improved sensitivity. It also incorporates a new machine-learning approach that is trained to assign a confidence score to each assembled circRNA, which is shown superior to using abundance for scoring. TERRACE is compared with leading circRNA detection methods on both simulations and biological datasets. Our method consistently outperforms by a large margin in sensitivity while maintaining better or comparable precision. In particular, when the annotations are not provided, TERRACE can assemble 123%-412% more correct circRNAs than state-of-the-art methods on human tissues. TERRACE presents a major leap on assembling full-length circRNAs from RNA-seq data, and we expect it to be widely used in the downstream research on circRNAs.

bioinformatics↗

bioRxiv2024

Capturing Snapshots of Nucleosomal H2A K13/K15 Ubiquitination Mediated by the Monomeric E3 Ligase RNF168

AbstractsThe DNA damage repair regulatory protein RNF168, a monomeric RING-type E3 ligase, plays a crucial role in regulating cell fate and DNA repair by specific and efficient ubiquitination of the adjacent Lys13 and Lys15 sites at the H2A N-terminal tail. However, understanding how RNF168 coordinates with its cognate E2 enzyme UbcH5c to ubiquitinate H2AK13/15 site-specifically has long been hampered by the lack of high-resolution structures of RNF168 and UbcH5c[~]Ub in complex with nucleosomes. Here, we developed mechanism-based chemical trapping strategies and determined the cryo-EM structures of the RNF168/UbcH5c-Ub/NCP complex captured in transient H2AK13/15 monoubiquitination and adjacent dual-monoubiquitination reactions. Our structural analysis revealed that RNF168 stably binds to the nucleosomal H2A-H2B acidic patch through a basic helix with multiple interactions, which positions the UbcH5c active centre directly over the H2A N-terminus, providing a "helix-anchoring" mode for monomeric E3 ligase RNF168 on nucleosome in contrast to the "compass-binding" mode of dimeric E3 ligases. Furthermore, our chemically synthesized ubiquitinated histones have enabled the elucidation of the efficiency of Ub installation and the interplay between the initial and subsequent Ub modifications on the adjacent H2A K13 and K15 sites. Overall, our work not only provides structural snapshots of H2A K13/K15 site-specific monoubiquitination and adjacent dual-monoubiquitination, but also offers a near-atomic resolution structural framework for understanding how pathogenic mutations or physiological modifications affect the molecular function of RNF168 in H2A K13/15 ubiquitination.

biochemistry↗

bioRxiv2023

Pharmacokinetics, Tissue Distribution, and Formulation Study of a Small-molecule Inhibitor of MKLP2, LG157

LG157 is a recently identified small-molecule inhibitor of mitotic kinesin-like protein 2 (MKLP2), an overlooked oncology target. This study aims to explore the drug developability of LG157, by assessing its druglike properties, determining plasma drug exposure in various oral formulations, and exploring the self-emulsifying drug delivery system (SEDDS). Solubility of LG157 ranges from 175 to 228 M across pH 1.0 to 13.0, with a LogD of 2.41 at pH 7.4. It showed a high protein binding rate of 92.58% in mouse plasma and 90.30% in human serum. The bioavailability radar plot aligns with experimental data (69-85%), indicating good bioavailability. In line with the computation prediction, preclinical formulation studies in mice reveal that all five formulations tested offer decent plasma LG157 exposure, with the highest level of LG157 exposure in the PEG300-based formulation. Subsequent tissue distribution studies in rats indicated that the compound is widely distributed with the highest concentration of LG157 in the liver and the lowest level in the brain. The optimal SEDDS formulation, SEDDS-F14, consists of 65% Oleic acid, 26.25% Tween 20, and 8.75% PEG400 as oil, surfactant, and co-surfactant, respectively. SEDDS optimization, based on the central composite design, has achieved the maximum loading of 188.7 mg/mL for LG157. These findings support the developability of LG157 and encourage continued exploration and refinement of formulations for improved therapeutic efficacy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/573327v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@11b4bb7org.highwire.dtl.DTLVardef@107e320org.highwire.dtl.DTLVardef@d06f55org.highwire.dtl.DTLVardef@3d4854_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

ARBUR: a Machine Learning-based Analysis System for Relating Behaviors and Ultrasonic Vocalizations of Rats

Deciphering how different types of behavior and ultrasonic vocalizations (USVs) of rats interact can yield insights into the neural basis of social interaction. However, the behavior-vocalization interplay of rats remains elusive because of the challenges of relating the two communication media in complex social contexts. Here, we propose a machine learning-based analysis system (ARBUR) that can cluster without bias both non-step (continuous) and step USVs, hierarchically detect eight types of behavior of two freely behaving rats with high accuracy, and locate the vocal rat in 3-D space. By simultaneously recording the video and ultrasonic streams of two freely behaving rats, ARBUR reveals that rats communicate via distinct USVs when engaging in different types of social behavior. Moreover, we show that ARBUR can not only automatically reveal the well-understood behavior-associated vocalizations that were carefully concluded by other behavioral researchers, but also hold the promise to indicate novel findings that can be hardly found by manual analysis, especially regarding step USVs and the active/passive rat-associated USVs during easy-to-confuse social behaviors. This work highlights the potential of machine learning algorithms in automatic animal behavioral and acoustic analysis and could help mechanistically understand the interactive influence between the behaviors and USVs of rats.

animal behavior and cognition↗

bioRxiv2023

MYC amplifies mitotic perturbations elicited by LXY18 to enable synthetic lethality

The MYC oncoprotein represents an intriguing target for cancer treatment, but its therapeutic potential has been hindered by the absence of specific pharmacological inhibitors. In this study, we demonstrate that the phenoxy quinoline compound LXY18 selectively targets and eliminates cells overexpressing MYC, leaving non-transformed cells unharmed. This synthetic lethality arises from an acute induction of multipolarity, resulting in a persistent arrest in early mitosis followed by cell death in mitosis or after mitotic slippage. Distinctively, LXY18s action contrasts with other antimitotic compounds, as they either fail to induce mitotic arrest or elicit mitotic arrest irrespective of MYC abundance. Furthermore, the MYC abundance in a panel of 98 tumor cell lines correlates with their sensitivity to LXY18. Collectively, our findings uncover LXY18 as an MYC- enabled mitotic blocker and open a new avenue to selectively target MYC-overexpressing tumor cells without affecting normal cells.

cancer biology↗

bioRxiv2023

mTORC1/S6K1 signaling promotes sustained oncogenic translation through modulating CRL3IBTK-mediated non-degradative ubiquitination of eIF4A1

Enhanced protein synthesis is a crucial molecular mechanism that allows cancer cells to survive, proliferate, metastasize, and develop resistance to anti-cancer treatments, and often arises as a consequence of increased signaling flux channeled to mRNA-bearing eukaryotic initiation factor 4F (eIF4F). However, the post-translational regulation of eIF4A1, an ATP-dependent RNA helicase and subunit of the eIF4F complex, is still poorly understood. Here, we demonstrate that IBTK, a substrate-binding adaptor of Cullin 3-RING ubiquitin ligase (CRL3) complex, interacts with eIF4A1. The non-degradative ubiquitination of eIF4A1 catalyzed by CRL3IBTK complex promotes cap-dependent translational initiation, nascent protein synthesis, oncogene expression, and tumor cell growth both in vivo and in vitro. Moreover, we show that mTORC1 and S6K1, two key regulators of protein synthesis, directly phosphorylate IBTK to augment eIF4A1 ubiquitination and sustained oncogenic translation. This link between the CRL3IBTK complex and the mTORC1/S6K1 signaling pathway, which is frequently dysregulated in cancer, represents a promising target for anti-cancer therapies. Statement of Significance: Overexpression of IBTK contributes to the process of tumorigenesis by amplifying translation, and represents a promising target for anti-cancer therapies.

cancer biology↗

bioRxiv2023

Rationally designed multimeric nanovaccines using icosahedral DNA origami for molecularly controlled display of SARS-CoV-2 receptor binding domain

Multivalent antigen display on nanoparticles can enhance the immunogenicity of nanovaccines targeting viral moieties, such as the receptor binding domain (RBD) of SARS-CoV-2. However, particle morphology and size of current nanovaccines are significantly different from those of SARS-CoV-2. Additionally, surface antigen patterns are not controllable to enable the optimization of B cell activation. Herein, we employed an icosahedral DNA origami (ICO) as a display particle for SARS-CoV-2 RBD nanovaccines. The morphology and diameter of the particles were close to those of the virus (91 {+/-} 11 nm). The surface addressability of the DNA origami permitted facile modification of the ICO surface with numerous RBD antigen clusters (ICO-RBD) to form various antigen patterns. Using an in vitro screening system, we demonstrate that the antigen spacing, antigen copies within clusters and cluster number parameters of the surface antigen pattern all impact the ability of the nanovaccines to activate B cells. Importantly, the optimized ICO-RBD nanovaccines evoked stronger and more enduring humoral and T cell immune responses in mouse models compared to soluble RBD antigens. Our vaccines activated similar humoral immunity and slightly stronger cellular immunity compared to mRNA vaccines. These results provide reference principles for the rational design of nanovaccines and exemplify the utility of DNA origami as a display platform for vaccines against infectious disease.

bioengineering↗

bioRxiv2023

The role of neutrophil typing in homeostatic resilience protective model of inflammatory preconditioning

Sepsis is a systemic inflammatory response syndrome (SIRS) characterized by a dysregulated host response to infection that results in organ dysfunction. The response of neutrophils to early inflammation is critical, interferon regulatory factors 4 (IRF4) and interferon regulatory factors 5 (IRF5) are expressed in most cell types of the immune system, but the relationship between the role of IRF4 and IRF5 in preconditioning-protected septic peritonitis mouse model and neutrophils response remains unknown. In this study, we used an E.coli-induced septic peritonitis mouse model and zebrafish model to explore the relationship between neutrophil inflammation and IRF subtype changes in the process of septic peritonitis. Mechanistically, we found that the protein complex formed by polymorphonuclear neutrophils (PMN) and IRF5/MyD88 can secrete pro-inflammatory factors and directly kill invading bacteria. Author SummaryNumerous animal and clinical sepsis studies have shown that markedly impaired recruitment of neutrophils to sites of infection and failure to clear bacteria contribute to excessive inflammation and increased mortality in sepsis. In our previous work, we established an Escherichia coli (E.coli) lethal septic peritonitis model and a preconditioning-protected septic peritonitis mouse model. In the early stage of septic peritonitis, a large number of PMN infiltrate the peritoneal cavity, which produces an inflammatory response to invasive bacteria. In this study, the switching process between pro-inflammatory and anti-inflammatory attracted our attention. Our research shows that IRF5-IRF4 regulatory axis leads to a PMN phenotype switch in sepsis and the expression of IRF5 and IRF4 was related to PMN pro-inflammatory (N1 type) and anti-inflammatory (N2 type) phenotypes, respectively.

immunology↗

bioRxiv2023

Long-read Transcriptome Landscapes of Primary and Metastatic Liver Cancers at Transcript Resolution

BackgroundThe liver is the sixth most common site of primary cancer in humans and is frequently colonized by metastases from cancers of other organs. Few studies have investigated the transcriptomic profiles of matched primary tumor and hepatic metastases of patients. Moreover, the read length of 100-200 bases in conventional short-read RNA sequencing is too short, which makes it difficult to directly infer the full-length transcript structure. To help develop effective treatments and improve survival, it is crucial to understand the complex and diverse molecular mechanisms of primary and metastatic liver cancers. MethodsNinety-five primary and secondary liver cancer patients who underwent hepatic resection were included with long-read sequencing isoform-sequencing and short-read RNA sequencing. We compared the transcriptome landscapes of primary and metastatic liver cancers and systematically investigated HCC, paired primary tumors and liver metastases, and matched non-tumor liver tissues. ResultsWe defined the full-length isoform-level transcriptome of human primary and metastatic liver cancers and identified isoform-level diversity in HCC and metastasis-associated transcriptome variations in metastatic liver cancers. Specific RNA transcripts and isoform switching events with clinical implications were profoundly discovered in liver cancer. Metastasis-specific transcripts that can predict the metastatic risk and identify the primary sites of cancers of unknown primary liver metastasis patients were defined. Additionally, we found that adjacent paracancerous liver tissues are abnormal and characterized the premetastatic immunological and metabolic alterations in the liver that favor the spread of cancer metastases. ConclusionsOur findings strongly highlight the powerfulness of full-length transcriptome profiling to yield novel biological insights into understanding the molecular basis of tumorigenesis and will further benefit the treatment of primary and metastatic liver cancers.

genomics↗

bioRxiv2023

A Cryptic Basic Groove formed by Ubiquitin and Histone H3 Mediates the Selective Recognition of H2AK119Ub Nucleosomes by Synovial Sarcoma X Breakpoint 1 Protein

The cancer-specific fusion oncoprotein SS18-SSX1 disturbs chromatin accessibility by hijacking the BAF complex from the promoters and enhancers to the polycomb-repressed chromatin regions. This process relies on the selective recognition of H2AK119Ub nucleosomes by SSX1. However, the mechanism by which SSX1 selective recognition of H2AK119Ub nucleosomes in the absence of ubiquitin (Ub)-binding capacity remains unknown. Here we report the cryo-EM structure of SSX1 bound to H2AK119Ub nucleosomes at 3.1 [A] resolution. Combined in vitro biochemical and cellular assays revealed that the Ub recognition by SSX1 is unique and depends on a cryptic basic groove formed by H3 and the Ub motif on the H2AK119 site. Moreover, this unorthodox binding mode of SSX1 induces DNA unwrapping at the entry/exit sites. Together, our results describe a unique mode of site-specific ubiquitinated nucleosome recognition that underlies the specific hijacking of the BAF complex to polycomb regions by SS18-SSX1 in synovial sarcoma.

molecular biology↗

bioRxiv2023

Characterization of mitotic phenotypes associated with a MYC synthetic lethal compound

Therapeutic targeting of MYC directly has proven difficult, but several means to target MYC indirectly using a synthetic lethal drug approach have been proposed. Synthetic lethal approaches for MYC have sought to take advantage of vulnerabilities MYC imposes related to either metabolic reprogramming, apoptotic signaling or the cycling of cancer cells. Here, we describe in detail the cell division phenotypes induced by a MYC synthetic lethal compound, dimethylfasudil (diMF). DiMF is a known ROCK inhibitor, but structurally related ROCK inhibitors are not synthetic lethal with MYC, so the activity of diMF is not related to blockade of this family of kinases. Instead, this compound induced multiple cell cycle-related liabilities. These included the early mitotic arrest of cycling cells followed by mitotic catastrophe-induced death and the induction of polyploidy in cells that do manage to pass through mitosis. As early as prometaphase, we noted diminished staining for BUB1 kinase, which binds to kinetochores and regulates the mitotic spindle checkpoint and chromosome congression. Kinetochore proteins, such as CENP-F, failed to localize at the metaphase plate, confirming a deficit in centromere assembly. This, presumably, contributed to the development of segregation anomalies in diMF-treated cells. In anaphase cells, the protein regulator of cytokinesis 1 (PRC1), failed to be recruited to the midzone, leading to a cascade of defects that included failed recruitment of the chromosomal passenger protein complex, the centralspindlin complex and polo-like-kinase 1 (PLK1). These observations correlate well with the cell death phenotypes induced by diMF, which may serve as a prototype MYC synthetic lethal compound to explore synthetic lethal therapy or as a scaffold upon which to build superior compounds. The phenotypes described here serve as examples of MYC synthetic lethal drug effects that can be used to explore and maximize drug discovery programs.

cancer biology↗

bioRxiv2023

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

microbiology↗