Investigation into in silico and in vitro approaches for inhibitors targeting MCM10 in Leishmania donovani: a comprehensive study.

Visceral Leishmaniasis (VL), the second neglected tropical disease caused by various Leishmania species, presents a significant public health challenge due to limited treatment options and the absence of vaccines. The agent responsible for visceral leishmaniasis, also referred to as "black fever" in India, is Leishmania donovani. This study focuses on L. donovani Minichromosome maintenance 10 (LdMcm10), a crucial protein in the DNA replication machinery, as a potential therapeutic target in Leishmania therapy using in silico and in vitro approaches. We employed bioinformatics tools, molecular docking, and molecular dynamics simulations to predict potential inhibitors against the target protein. The research revealed that the target protein lacks homologues in the host, emphasizing its potential as a drug target. Ligands from the DrugBank database were screened against LdMcm10 using PyRx software. The top three compounds, namely suramin, vapreotide, and pasireotide, exhibiting the best docking scores, underwent further investigation through molecular dynamic simulation and in vitro analysis. The observed structural dynamics suggested that LdMcm10-ligand complexes maintained consistent binding throughout the 300 ns simulation period, with minimal variations in their backbone. These findings suggest that these three compounds hold promise as potential lead compounds for developing new drugs against leishmaniasis. In vitro experiments also demonstrated a dose-dependent reduction in L. donovani viability for suramin, vapreotide, and pasireotide, with computed IC50 values providing quantitative metrics of their anti-leishmanial efficacy. The research offers a comprehensive understanding of LdMcm10 as a drug target and provides a foundation for further investigations and clinical exploration, ultimately advancing drug discovery strategies for leishmaniasis treatment.

RNF4 prevents genomic instability caused by chronic DNA under-replication.

Eukaryotic genome stability is maintained by a complex and diverse set of molecular processes. One class of enzymes that promotes proper DNA repair, replication and cell cycle progression comprises small ubiquitin-like modifier (SUMO)-targeted E3 ligases, or STUbLs. Previously, we reported a role for the budding yeast STUbL synthetically lethal with sgs1 (Slx) 5/8 in preventing G2/M-phase arrest in a minichromosome maintenance protein 10 (Mcm10)-deficient model of replication stress. Here, we extend these studies to human cells, examining the requirement for the human STUbL RING finger protein 4 (RNF4) in MCM10 mutant cancer cells. We find that MCM10 and RNF4 independently promote origin firing but regulate DNA synthesis epistatically and, unlike in yeast, the negative genetic interaction between RNF4 and MCM10 causes cells to accumulate in G1-phase. When MCM10 is deficient, RNF4 prevents excessive DNA under-replication at hard-to-replicate regions that results in large DNA copy number alterations and severely reduced viability. Overall, our findings highlight that STUbLs participate in species-specific mechanisms to maintain genome stability, and that human RNF4 is required for origin activation in the presence of chronic replication stress.

A critical threshold of MCM10 is required to maintain genome stability during differentiation of induced pluripotent stem cells into natural killer cells.

Natural killer (NK) cell deficiency (NKD) is a rare disease in which NK cell function is reduced, leaving affected individuals susceptible to repeated viral infections and cancer. Recently, a patient with NKD was identified carrying compound heterozygous variants of MCM10 (minichromosome maintenance protein 10), an essential gene required for DNA replication, that caused a significant decrease in the amount of functional MCM10. NKD in this patient presented as loss of functionally mature late-stage NK cells. To understand how MCM10 deficiency affects NK cell development, we generated MCM10 heterozygous (MCM10+/-) induced pluripotent stem cell (iPSC) lines. Analyses of these cell lines demonstrated that MCM10 was haploinsufficient, similar to results in other human cell lines. Reduced levels of MCM10 in mutant iPSCs was associated with impaired clonogenic survival and increased genomic instability, including micronuclei formation and telomere erosion. The severity of these phenotypes correlated with the extent of MCM10 depletion. Significantly, MCM10+/- iPSCs displayed defects in NK cell differentiation, exhibiting reduced yields of hematopoietic stem cells (HSCs). Although MCM10+/- HSCs were able to give rise to lymphoid progenitors, these did not generate mature NK cells. The lack of mature NK cells coincided with telomere erosion, suggesting that NKD caused by these MCM10 variants arose from the accumulation of genomic instability including degradation of chromosome ends.

Immune modulation and prognostic significance of MCM10 in pan-cancer: a comprehensive analysis.

BACKGROUND: Oncogenic processes in cancer are often characterized by dysregulation of critical genes. Our study focused on the minichromosome maintenance 10 replication initiation factor (MCM10) gene's expression and its potential diagnostic and prognostic implications in pan-cancer. METHOD: Leveraging large-scale genomic datasets, and experimental validation we embarked on a comprehensive analysis to shed light on the diagnostic and prognostic role of MCM10. RESULTS: Our findings underscore the wide-ranging up-regulation of MCM10 across 24 major cancer types, positioning it as a ubiquitous player in tumorigenesis. Significantly, MCM10 up-regulation was strongly associated with poorer overall survival in Kidney Renal Papillary Cell Carcinoma (KIRP), Liver Hepatocellular Carcinoma (LIHC), and Lung Adenocarcinoma (LUAD), emphasizing its potential as a valuable prognostic marker in these cancers. While genetic mutations often drive oncogenic processes, our mutational analysis revealed the relative stability of MCM10 in KIRP, LIHC, and LUAD. This suggests that epigenetic (hypomethylation) and non-mutational regulatory mechanisms predominantly govern MCM10 expression in these cancer types. Further analyses demonstrated positive correlations between MCM10 expression and immune cell infiltration, particularly CD8+ T cells and CD4+ T cells, offering insights into the gene's influence on the tumor immune microenvironment. Additionally, pathway enrichment analysis highlighted MCM10-associated genes' involvement in crucial signaling pathways, such as the cell cycle, DNA replication, and repair. Exploring the therapeutic potential, we examined important drugs capable of regulating MCM10 expression, opening doors to personalized treatment strategies. CONCLUSION: Our study elucidates the multifaceted roles of MCM10 in KIRP, LIHC, and LUAD. Its pervasive up-regulation, prognostic significance, epigenetic regulation, and influence on the immune microenvironment provide valuable insights into these cancers. This research contributes to the growing body of evidence surrounding MCM10 and invites further investigation, validation, and potential translational efforts to harness its clinical relevance.

Mechanism of eukaryotic origin unwinding is a dual helicase DNA shearing process.

DNA replication in all cells begins with the melting of base pairs at the duplex origin to allow access to single-stranded DNA templates which are replicated by DNA polymerases. In bacteria, origin DNA is presumed to be melted by accessory proteins that allow loading of two ring-shaped replicative helicases around single-strand DNA (ssDNA) for bidirectional unwinding and DNA replication. In eukaryotes, by contrast, two replicative CMG (Cdc45-Mcm2-7-GINS) helicases are initially loaded head to head around origin double-strand DNA (dsDNA), and there does not appear to be a separate origin unwinding factor. This led us to investigate whether head-to-head CMGs use their adenosine triphosphate (ATP)-driven motors to initiate duplex DNA unwinding at the origin. Here, we show that CMG tracks on one strand of the duplex while surrounding it, and this feature allows two head-to-head CMGs to unwind dsDNA by using their respective motors to pull on opposite strands of the duplex. We further show that while CMG is capable of limited duplex unwinding on its own, the extent of unwinding is greatly and rapidly stimulated by addition of the multifunctional CMG-binding protein Mcm10 that is critical for productive initiation of DNA replication in vivo. On the basis of these findings, we propose that Mcm10 is a processivity or positioning factor that helps translate the work performed by the dual CMG motors at the origin into productive unwinding that facilitates bidirectional DNA replication.

Minichromosome maintenance protein 10 (mcm10) regulates hematopoietic stem cell emergence in the zebrafish embryo.

Hematopoietic stem cells (HSCs) guarantee the continuous supply of all blood lineages during life. In response to stress, HSCs are capable of extensive proliferative expansion, whereas in steady state, HSCs largely remain in a quiescent state to prevent their exhaustion. DNA replication is a very complex process, where many factors need to exert their functions in a perfectly concerted manner. Mini-chromosome-maintenance protein 10 (Mcm10) is an important replication factor, required for proper assembly of the eukaryotic replication fork. In this report, we use zebrafish to study the role of mcm10 during embryonic development, and we show that mcm10 specifically regulates HSC emergence from the hemogenic endothelium. We demonstrate that mcm10-deficient embryos present an accumulation of DNA damages in nascent HSCs, inducing their apoptosis. This phenotype can be rescued by knocking down p53. Taken all together, our results show that mcm10 plays an important role in the emergence of definitive hematopoiesis.

MCM10: An effective treatment target and a prognostic biomarker in patients with uterine corpus endometrial carcinoma.

Molecular profiling has been applied for uterine corpus endometrial carcinoma (UCEC) management for many years. The aim of this study was to explore the role of MCM10 in UCEC and construct its overall survival (OS) prediction models. Data from TCGA, GEO, cbioPotal and COSMIC databases and the methods, such as GO, KEGG, GSEA, ssGSEA and PPI, were employed to bioinformatically detect the effects of MCM10 on UCEC. RT-PCR, Western blot and immunohistochemistry were used to validate the effects of MCM10 on UCEC. Based on Cox regression analysis using the data from TCGA and our clinical data, two OS prediction models for UCEC were established. Finally, the effects of MCM10 on UCEC were detected in vitro. Our study revealed that MCM10 was variated and overexpressed in UCEC tissue and involved in DNA replication, cell cycle, DNA repair and immune microenvironment in UCEC. Moreover, silencing MCM10 significantly inhibited the proliferation of UCEC cells in vitro. Importantly, based on MCM10 expression and clinical features, the OS prediction models were constructed with good accuracy. MCM10 could be an effective treatment target and a prognostic biomarker for UCEC patients. The OS prediction models might help establish the strategies of follow-up and treatment for UCEC patients.

RTEL1 and MCM10 overcome topological stress during vertebrate replication termination.

Topological stress can cause converging replication forks to stall during termination of vertebrate DNA synthesis. However, replication forks ultimately overcome fork stalling, suggesting that alternative mechanisms of termination exist. Using proteomics in Xenopus egg extracts, we show that the helicase RTEL1 and the replisome protein MCM10 are highly enriched on chromatin during fork convergence and are crucially important for fork convergence under conditions of topological stress. RTEL1 and MCM10 cooperate to promote fork convergence and do not impact topoisomerase activity but do promote fork progression through a replication barrier. Thus, RTEL1 and MCM10 play a general role in promoting progression of stalled forks, including when forks stall during termination. Our data reveal an alternate mechanism of termination involving RTEL1 and MCM10 that can be used to complete DNA synthesis under conditions of topological stress.

Optimizing CMG helicase and CMG-dependent replication assays by designing DNA fork substrates and choosing nucleotide analogues for helicase preloading.

The replication machinery that synthesizes new copies of chromosomal DNA is located at the junction where double-stranded DNA is separated into its two strands. This replication fork DNA structure is at the heart of most assays involving DNA helicases. The helicase enzyme unwinds the replication fork structure into two single-stranded templates which are converted into two daughter duplexes by other proteins, including DNA polymerases. In eukaryotes, the CMG (Cdc45/Mcm2-7/GINS) helicase plays the pivotal role of unwinding the parental duplex DNA and at the same time interacts with numerous other proteins, including the leading strand polymerase, Pol ɛ. This chapter first describes how we design and prepare synthetic replication forks used in our CMG-related assays. Then we describe how to load CMG onto the fork. The Mcm2-7 motor subunits of CMG form a closed ring, as do all cellular replicative helicases, that encircles ssDNA for helicase function. Thus, the first step in these assays is the loading of CMG onto the fork DNA, followed by DNA unwinding and replication. We explain protocols for different strategies of preloading CMG onto the DNA fork using different ATP analogues. Additionally, the presence of Mcm10, an intimate partner of CMG, affects how CMG is preloaded onto a fork substrate.

Over-Activation of Minichromosome Maintenance Protein 10 Promotes Genomic Instability in Early Stages of Breast Cancer.

Genomic instability is considered as one of the key hallmark during cancer development and progression. Cellular mechanisms, such as DNA replication initiation, DNA damage and repair response, apoptosis etc are observed to block progression of genomic instability and thereby induce protective effects against cancer. DNA replication initiation protein MCM10 has been previously observed to have an increased expression in different cancer subtypes. However, MCM10 association with genomic instability, cancer development and its relevant mechanisms remain unknown. Here, using a breast cancer model, we observe a significant association of MCM10 with the degree of clinical aggressiveness in breast cancer patients. By overexpression of MCM10, we observed that MCM10 promotes tumorigenic properties in immortal non-tumorigenic mammary cells by increasing proliferation, shortening the cell cycle, and promoting tumorigenic characters in in-vivo mimicking conditions. Furthermore, overexpression of MCM10 is found to induce accumulation of ssDNA followed by overexpression of ssDNA binding protein RPA2. Mesenchymal markers such as up-regulation of Vimentin, transcription factor Snail and Twist2, and the down-regulation of E-cadherin were observed in MCM10 overexpression cells. Overall, the findings of this study revealed a novel mechanism by which MCM10 promotes genomic instability and breast cancer progression, and effectively differentiates the active degree of breast cancer aggressiveness. Thus, MCM10 has the potential to be a clinically useful biomarker as well as a therapeutic target for future breast cancer treatment.

MCM10 is a Prognostic Biomarker and Correlated With Immune Checkpoints in Ovarian Cancer.

Background: Microchromosome maintenance protein 10 (MCM10) is required for DNA replication in all eukaryotes, and it plays a key role in the development of many types of malignancies. However, we currently still do not know the relationship between MCM10 and ovarian cancer (OV) prognosis and immune checkpoints. Methods: The Gene Expression Profiling Interactive Analysis and Tumor Immunology Estimation Resource (TIMER) databases were used to investigate MCM10 expression in Fan cancer. The Kaplan-Meier Plotter and PrognoScan were used to assess the relationship between MCM10 and OV prognosis. The LinkedOmics database was used to analyze the MCM10 co-expression network and explore GO term annotation and the KEGG pathway. The relationship between MCM10 expression and immune infiltration in OV was investigated using the Tumor Immunology Estimation Resource database. cBioPortal database was used to explore the relationship between MCM10 expression and 25 immune checkpoints. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect MCM10 expression. The prognosis was also analyzed by distinguishing between high and low expression groups based on median expression values. Results: The results of the three data sets (220,651_s_at, 222,962_s_at and 223,570_at) in KM Plotter all indicated that the overall survivalof the high MCM10 expression group was lower than that of the low expression group OV, and the results of GSE9891 also reached the same conclusion. The expression level of MCM10 was negatively correlated with B cells and CD8+T cells, and positively correlated with CD4+T Cells and Macrophages. GO term annotation and KEGG pathway analysis showed that the co-expressed genes of MCM10 were mainly enriched in cell cycle and DNA replication. The alterations in MCM10 coexisted statistically with the immune checkpoints CTLA4, TNFSF4, TNFSF18, CD80, ICOSLG, LILRB1 and CD200. PCR results displayed that MCM10 was highly expressed in OV tissues, and the increased expression of MCM10 was significantly associated with poor overall survival. Conclusion: These results demonstrated that high expression of MCM10 was associated with poor prognosis in OV and correlated with immune checkpoints.

Prognostic significance and function of MCM10 in human hepatocellular carcinoma.

Aim: To investigate the role of MCM10, a conserved replication factor, in hepatocellular carcinoma (HCC). Methods: We used data from 364 HCC patients in the Cancer Genome Atlas database and conducted in vitro experiments to confirm the role of MCM10. Results: High MCM10 expression correlated with poor HCC patient outcome and was an independent prognosticator for HCC. Time-dependent receiver operating characteristic curve analysis found that the sequential trend of MCM10 for survival was not inferior to that of the tumor node metastasis stage. The MCM10 model had a higher C-index than the non-MCM10 model, indicating that incorporating MCM10 into a multivariate model improves the model's prognostic accuracy for HCC. Genetic alterations of MCM10 prominently correlated with an unfavorable HCC outcome. Conclusion: Our findings strongly suggest using the MCM10 gene as a prognostic indicator in HCC.

Lay abstract Hepatocellular carcinoma is one of the most aggressive malignant cancers globally. Our study investigated the role of a conserved replication factor, MCM10, in hepatocellular carcinoma. We performed some bioinformatics analysis and in vitro experiments, and successfully found that MCM10 has a good predictive value for survival in patients with hepatocellular carcinoma.

Aberrant MCM10 SUMOylation induces genomic instability mediated by a genetic variant associated with survival of esophageal squamous cell carcinoma.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is one of the common gastrointestinal malignancy with an inferior prognosis outcome. DNA replication licensing aberration induced by dysregulation of minichromosome maintenance proteins (MCMs) causes genomic instability and cancer metastasis. SUMOylation modification plays a pivotal role in regulation of genomic integrity, while its dysregulation fueled by preexisting germline variants in cancers remains poorly understood. METHODS: Firstly, we conducted two-stage survival analysis consisting of an exome-wide association study in 904 ESCC samples and another independent 503 ESCC samples. Then, multipronged functional experiments were performed to illuminate the potential biological mechanisms underlying the promising variants, and MCM10 influences the ESCC progression. Finally, we tested the effects of MCM10 inhibitors on ESCC cells. RESULTS: A germline variant rs2274110 located at the exon 15 of MCM10 was identified to be significantly associated with the prognosis of ESCC patients. Individuals carrying rs2274110-AA genotypes confer a poor survival (hazard ratio = 1.61, 95% confidence interval = 1.35-1.93, p = 1.35 × 10-7 ), compared with subjects carrying rs2274110-AG/GG genotypes. Furthermore, we interestingly found that the variant can increase SUMOylation levels at K669 site (Lys[K]699Arg[R]) of MCM10 protein mediated by SUMO2/3 enzymes, which resulted in an aberrant overexpression of MCM10. Mechanistically, aberrant overexpression of MCM10 facilitated the proliferation and metastasis abilities of ESCC cells in vitro and in vivo by inducing DNA over-replication and genomic instability, providing functional evidence to support our population finding that high expression of MCM10 is extensively presented in tumor tissues of ESCC and correlated with inferior survival outcomes of multiple cancer types, including ESCC. Finally, MCM10 inhibitors Suramin and its analogues were revealed to effectively block the metastasis of ESCC cells. CONCLUSIONS: These findings not only demonstrate a potential biological mechanism between aberrant SUMOylation, genomic instability and cancer metastasis, but also provide a promising biomarker aiding in stratifying ESCC individuals with different prognosis, as well as a potential therapeutic target MCM10.

High expression of MCM10 is predictive of poor outcomes in lung adenocarcinoma.

BACKGROUNDS: Lung adenocarcinoma is a complex disease that results in over 1.8 million deaths a year. Recent advancements in treating and managing lung adenocarcinoma have led to modest decreases in associated mortality rates, owing in part to the multifactorial etiology of the disease. Novel prognostic biomarkers are needed to accurately stage the disease and act as the basis of adjuvant treatments. MATERIAL AND METHODS: The microarray datasets GSE75037, GSE31210 and GSE32863 were downloaded from the Gene Expression Omnibus (GEO) database to identify prognostic biomarkers for lung adenocarcinoma and therapy. The differentially expressed genes (DEGs) were identified by GEO2R. Functional and pathway enrichment analysis were performed by Kyoto Encyclopedia of Genes and Genomes and Gene Ontology (GO). Validation was performed based on 72 pairs of lung adenocarcinoma and adjacent normal lung tissues. RESULTS: Results showed that the DEGs were mainly focused on cell cycle and DNA replication initiation. Forty-one hub genes were identified and further analyzed by CytoScape. Here, we provide evidence which suggests MCM10 is a potential target with prognostic, diagnostic and therapeutic value. We base this on an integrated approach of comprehensive bioinformatics analysis and in vitro validation using the A549 lung adenocarcinoma cell line. We show that MCM10 overexpression correlates with a poor prognosis, while silencing of this gene decreases aberrant growth by 2-fold. Finally, evaluation of 72 clinical biopsy samples suggests that overexpression of MCM10 in the lung adenocarcinoma highly correlates with larger tumor size. Together, this work suggests that MCM10 may be a clinically relevant gene with both predictive and therapeutic value in lung adenocarcinoma.

MCM10 Acts as a Potential Prognostic Biomarker and Promotes Cell Proliferation in Hepatocellular Carcinoma: Integrated Bioinformatics Analysis and Experimental Validation.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common human malignant tumors. The prognosis of HCC patients is still unsatisfying. Thus, it is of great importance to identify novel molecules and functional pathways associated with the pathophysiology of HCC. In this study, we performed the integrated bioinformatics analysis and experiment validation to identify novel biomarkers in the prognosis and progression of HCC. MATERIALS AND METHODS: Gene expression profiles were obtained from Gene Expression Omnibus database (GSE33294) for the screening of the differentially expressed genes (DEGs) between HCC tissues and matched non-tumor tissues. The DEGs were subjected to Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and Gene Set Enrichment Analysis (GSEA). The key genes in HCC were further subjected to overall survival analysis of HCC patients. The in vitro functional studies were performed to validate the biological functions of the key gene in HCC cell progression. RESULTS: A total of 2,334 DEGs were screened from GSE33294 dataset, including 1,120 up-regulated and 1,214 down-regulated genes. GO, KEGG and GSEA results showed that DEGs are significantly associated with the biological process of cell cycle, cell division and DNA replication. The Kaplan-Meier survival analysis results showed that the key genes from the minichromosome maintenance protein complex (MCM) family including MCM8, MCM10, MCM2, MCM3, MCM4, MCM6 and MCM7 were significantly correlated with the overall survival of the HCC patients. Further validation studies showed that MCM10 was significantly up-regulated in the HCC cell lines, and knockdown of MCM10 significantly suppressed cell proliferation as determined by the cell counting kit-8 and BrdU incorporation assays and increased the caspase-3 activity of HCC cells. CONCLUSION: The comprehensive bioinformatics analysis identified several key genes that were associated with the prognosis of HCC patients. The validation study results indicated that MCM10 may be an important predictor for poorer prognosis of HCC patients and may act as an oncogene to promote HCC cell progression.

Knockdown of MCM10 Gene Impairs Glioblastoma Cell Proliferation, Migration and Invasion and the Implications for the Regulation of Tumorigenesis.

Minichromosome maintenance 10 (MCM10) plays an important role in DNA replication and is expressed in a variety of tumors, including glioma. However, its role and mechanism in glioma remain elusive. The purpose of this study was to examine the molecular function of MCM10 in glioblastoma cell lines in vitro and to further investigate the molecular mechanisms in the network mediated by MCM10. Cell proliferation, invasion, and migration were investigated in the absence of MCM10 mediated by RNA interference (RNAi) in U87 and U251 cell lines. Microarray data were obtained from U87 cells infected with a lentivirus expressing a small interfering RNA (siRNA) targeting MCM10, and ingenuity pathway analysis (IPA) was performed. Molecular signaling pathways, gene functions, and upstream and downstream regulatory genes and networks were analyzed. MCM10 was positively stained in human glioblastoma multiforme (GBM) samples according to immunohistochemistry. Silencing MCM10 in U87 and U251 cells significantly reduced cell proliferation, migration, and invasion. In U87 cells transfected with MCM10, 274 genes were significantly upregulated, while 313 genes were downregulated. IPA revealed that MCM10 is involved in the IGF-1 signaling pathway, and calcitriol appears to be a significant upstream regulator of MCM10. Other factors, such as TWIST1 and Stat3, also interact within the MCM10-mediated network. Our data indicate that MCM10 is involved in the regulation of GBM in vitro and may provide more evidence for understanding the molecular mechanisms of this fatal disease.

Distinct MCM10 Proteasomal Degradation Profiles by Primate Lentiviruses Vpr Proteins.

Viral protein R (Vpr) is an accessory protein found in various primate lentiviruses, including human immunodeficiency viruses type 1 and 2 (HIV-1 and HIV-2) as well as simian immunodeficiency viruses (SIVs). Vpr modulates many processes during viral lifecycle via interaction with several of cellular targets. Previous studies showed that HIV-1 Vpr strengthened degradation of Mini-chromosome Maintenance Protein10 (MCM10) by manipulating DCAF1-Cul4-E3 ligase in proteasome-dependent pathway. However, whether Vpr from other primate lentiviruses are also associated with MCM10 degradation and the ensuing impact remain unknown. Based on phylogenetic analyses, a panel of primate lentiviruses Vpr/x covering main virus lineages was prepared. Distinct MCM10 degradation profiles were mapped and HIV-1, SIVmus and SIVrcm Vprs induced MCM10 degradation in proteasome-dependent pathway. Colocalization and interaction between MCM10 with these Vprs were also observed. Moreover, MCM10 2-7 interaction region was identified as a determinant region susceptible to degradation. However, MCM10 degradation did not alleviate DNA damage response induced by these Vpr proteins. MCM10 degradation by HIV-1 Vpr proteins was correlated with G2/M arrest, while induction of apoptosis and oligomerization formation of Vpr failed to alter MCM10 proteolysis. The current study demonstrated a distinct interplay pattern between primate lentiviruses Vpr proteins and MCM10.

The anti-parasitic agent suramin and several of its analogues are inhibitors of the DNA binding protein Mcm10.

Minichromosome maintenance protein 10 (Mcm10) is essential for DNA unwinding by the replisome during S phase. It is emerging as a promising anti-cancer target as MCM10 expression correlates with tumour progression and poor clinical outcomes. Here we used a competition-based fluorescence polarization (FP) high-throughput screening (HTS) strategy to identify compounds that inhibit Mcm10 from binding to DNA. Of the five active compounds identified, only the anti-parasitic agent suramin exhibited a dose-dependent decrease in replication products in an in vitro replication assay. Structure-activity relationship evaluation identified several suramin analogues that inhibited ssDNA binding by the human Mcm10 internal domain and full-length Xenopus Mcm10, including analogues that are selective for Mcm10 over human RPA. Binding of suramin analogues to Mcm10 was confirmed by surface plasmon resonance (SPR). SPR and FP affinity determinations were highly correlated, with a similar rank between affinity and potency for killing colon cancer cells. Suramin analogue NF157 had the highest human Mcm10 binding affinity (FP Ki 170 nM, SPR KD 460 nM) and cell activity (IC50 38 µM). Suramin and its analogues are the first identified inhibitors of Mcm10 and probably block DNA binding by mimicking the DNA sugar phosphate backbone due to their extended, polysulfated anionic structures.

Replication Fork Activation Is Enabled by a Single-Stranded DNA Gate in CMG Helicase.

The eukaryotic replicative helicase CMG is a closed ring around double-stranded (ds)DNA at origins yet must transition to single-stranded (ss)DNA for helicase action. CMG must also handle repair intermediates, such as reversed forks that lack ssDNA. Here, using correlative single-molecule fluorescence and force microscopy, we show that CMG harbors a ssDNA gate that enables transitions between ss and dsDNA. When coupled to DNA polymerase, CMG remains on ssDNA, but when uncoupled, CMG employs this gate to traverse forked junctions onto dsDNA. Surprisingly, CMG undergoes rapid diffusion on dsDNA and can transition back onto ssDNA to nucleate a functional replisome. The gate-distinct from that between Mcm2/5 used for origin loading-is intrinsic to CMG; however, Mcm10 promotes strand passage by enhancing the affinity of CMG to DNA. This gating process may explain the dsDNA-to-ssDNA transition of CMG at origins and help preserve CMG on dsDNA during fork repair.

Fine-tuning of the replisome: Mcm10 regulates fork progression and regression.

Several decades of research have identified Mcm10 hanging around the replisome making several critical contacts with a number of proteins but with no real disclosed function. Recently, the O'Donnell laboratory has been better able to map the interactions of Mcm10 with a larger Cdc45/GINS/MCM (CMG) unwinding complex placing it at the front of the replication fork. They have shown biochemically that Mcm10 has the impressive ability to strip off single-strand binding protein (RPA) and reanneal complementary DNA strands. This has major implications in controlling DNA unwinding speed as well as responding to various situations where fork reversal is needed. This work opens up a number of additional facets discussed here revolving around accessing the DNA junction for different molecular purposes within a crowded replisome. Abbreviations: alt-NHEJ: Alternative Nonhomologous End-Joining; CC: Coli-Coil motif; CMG: Cdc45/GINS/MCM2-7; CMGM: Cdc45/GINS/Mcm2-7/Mcm10; CPT: Camptothecin; CSB: Cockayne Syndrome Group B protein; CTD: C-Terminal Domain; DSB: Double-Strand Break; DSBR: Double-Strand Break Repair; dsDNA: Double-Stranded DNA; GINS: go-ichi-ni-san, Sld5-Psf1-Psf2-Psf3; HJ Dis: Holliday Junction dissolution; HJ Res: Holliday Junction resolution; HR: Homologous Recombination; ICL: Interstrand Cross-Link; ID: Internal Domain; MCM: Minichromosomal Maintenance; ND: Not Determined; NTD: N-Terminal Domain; PCNA: Proliferating Cell Nuclear Antigen; RPA: Replication Protein A; SA: Strand Annealing; SE: Strand Exchange; SEW: Steric Exclusion and Wrapping; ssDNA: Single-Stranded DNA; TCR: Transcription-Coupled Repair; TOP1: Topoisomerase.