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Molecular Cell Mar 2017The efficient removal of replication and recombination intermediates is essential for the maintenance of genome stability. Resolution of these potentially toxic...
The efficient removal of replication and recombination intermediates is essential for the maintenance of genome stability. Resolution of these potentially toxic structures requires the MUS81-EME1 endonuclease, which is activated at prometaphase by formation of the SMX tri-nuclease containing three DNA repair structure-selective endonucleases: SLX1-SLX4, MUS81-EME1, and XPF-ERCC1. Here we show that SMX tri-nuclease is more active than the three individual nucleases, efficiently cleaving replication forks and recombination intermediates. Within SMX, SLX4 co-ordinates the SLX1 and MUS81-EME1 nucleases for Holliday junction resolution, in a reaction stimulated by XPF-ERCC1. SMX formation activates MUS81-EME1 for replication fork and flap structure cleavage by relaxing substrate specificity. Activation involves MUS81's conserved N-terminal HhH domain, which mediates incision site selection and SLX4 binding. Cell cycle-dependent formation and activation of this tri-nuclease complex provides a unique mechanism by which cells ensure chromosome segregation and preserve genome integrity.
Topics: Cell Cycle; DNA; DNA Repair; DNA Replication; DNA-Binding Proteins; Endodeoxyribonucleases; Endonucleases; Enzyme Activation; Genomic Instability; Humans; Multienzyme Complexes; Nucleic Acid Conformation; Protein Binding; Protein Interaction Domains and Motifs; Recombinases; Structure-Activity Relationship; Time Factors
PubMed: 28257701
DOI: 10.1016/j.molcel.2017.01.031 -
Journal of Cell Science May 2021Myosin XIX (Myo19) is an actin-based motor that competes with adaptors of microtubule-based motors for binding to the outer mitochondrial transmembrane proteins Miro1...
Myosin XIX (Myo19) is an actin-based motor that competes with adaptors of microtubule-based motors for binding to the outer mitochondrial transmembrane proteins Miro1 and Miro2 (collectively Miro, also known as RhoT1 and RhoT2, respectively). Here, we investigate which mitochondrial and cellular processes depend on the coordination of Myo19 and microtubule-based motor activities. To this end, we created Myo19-deficient HEK293T cells. Mitochondria in these cells were not properly fragmented at mitosis and were partitioned asymmetrically to daughter cells. Respiratory functions of mitochondria were impaired and ROS generation was enhanced. On a cellular level, cell proliferation, cytokinesis and cell-matrix adhesion were negatively affected. On a molecular level, Myo19 regulates focal adhesions in interphase, and mitochondrial fusion and mitochondrially associated levels of fission protein Drp1 and adaptor proteins dynactin and TRAK1 at prometaphase. These alterations were due to a disturbed coordination of Myo19 and microtubule-based motor activities by Miro.
Topics: Actins; HEK293 Cells; Humans; Mitochondria; Mitochondrial Dynamics; Mitochondrial Membranes; Mitochondrial Proteins; Myosins; rho GTP-Binding Proteins
PubMed: 34013964
DOI: 10.1242/jcs.255844 -
Cell Death & Disease Jun 2022CCAR2 (cell cycle and apoptosis regulator 2) is a multifaceted protein involved in cell survival and death following cytotoxic stress. However, little is known about the...
CCAR2 (cell cycle and apoptosis regulator 2) is a multifaceted protein involved in cell survival and death following cytotoxic stress. However, little is known about the physiological functions of CCAR2 in regulating cell proliferation in the absence of external stimuli. The present study shows that CCAR2-deficient cells possess multilobulated nuclei, suggesting a defect in cell division. In particular, the duration of mitotic phase was perturbed. This disturbance of mitotic progression resulted from premature loss of cohesion with the centromere, and inactivation of the spindle assembly checkpoint during prometaphase and metaphase. It resulted in the formation of lagging chromosomes during anaphase, leading ultimately to the activation of the abscission checkpoint to halt cytokinesis. The CCAR2-dependent mitotic progression was related to spatiotemporal regulation of active Aurora B. In conclusion, the results suggest that CCAR2 governs mitotic events, including proper chromosome segregation and cytokinetic division, to maintain chromosomal stability.
Topics: Aurora Kinase B; Cell Cycle Proteins; Centromere; Chromosome Segregation; Mitosis; Protein Serine-Threonine Kinases; Spindle Apparatus
PubMed: 35672287
DOI: 10.1038/s41419-022-04990-8 -
Biochemical Society Transactions Dec 2021Ki-67 is highly expressed in proliferating cells, a characteristic that made the protein a very important proliferation marker widely used in the clinic. However, the...
Ki-67 is highly expressed in proliferating cells, a characteristic that made the protein a very important proliferation marker widely used in the clinic. However, the molecular functions and properties of Ki-67 remained quite obscure for a long time. Only recently important discoveries have shed some light on its function and shown that Ki-67 has a major role in the formation of mitotic chromosome periphery compartment, it is associated with protein phosphatase one (PP1) and regulates chromatin function in interphase and mitosis. In this review, we discuss the role of Ki-67 during cell division. Specifically, we focus on the importance of Ki-67 in chromosome individualisation at mitotic entry (prometaphase) and its contribution to chromosome clustering and nuclear remodelling during mitotic exit.
Topics: Chromosomes, Human; Humans; Ki-67 Antigen; Mitosis
PubMed: 34783345
DOI: 10.1042/BST20210717 -
Nature Communications Jun 2023The centromere is the chromosome region where microtubules attach during cell division. In contrast to monocentric chromosomes with one centromere, holocentric species...
The centromere is the chromosome region where microtubules attach during cell division. In contrast to monocentric chromosomes with one centromere, holocentric species usually distribute hundreds of centromere units along the entire chromatid. We assembled the chromosome-scale reference genome and analyzed the holocentromere and (epi)genome organization of the lilioid Chionographis japonica. Remarkably, each of its holocentric chromatids consists of only 7 to 11 evenly spaced megabase-sized centromere-specific histone H3-positive units. These units contain satellite arrays of 23 and 28 bp-long monomers capable of forming palindromic structures. Like monocentric species, C. japonica forms clustered centromeres in chromocenters at interphase. In addition, the large-scale eu- and heterochromatin arrangement differs between C. japonica and other known holocentric species. Finally, using polymer simulations, we model the formation of prometaphase line-like holocentromeres from interphase centromere clusters. Our findings broaden the knowledge about centromere diversity, showing that holocentricity is not restricted to species with numerous and small centromere units.
Topics: Centromere; Cell Cycle Proteins; Cell Division; Chromatids; Heterochromatin
PubMed: 37311740
DOI: 10.1038/s41467-023-38922-7 -
Current Genetics Oct 2019Exogenous signals induce cells to enter the specialized cell division process of meiosis, which produces haploid gametes from diploid progenitor cells. Once cells... (Review)
Review
Exogenous signals induce cells to enter the specialized cell division process of meiosis, which produces haploid gametes from diploid progenitor cells. Once cells initiate the meiotic divisions, it is imperative that they complete meiosis. Inappropriate exit from meiosis and entrance into mitosis can create polyploid cells and can lead to germline tumors. Saccharomyces cerevisiae cells enter meiosis when starved of nutrients but can return to mitosis if provided nutrient-rich medium before a defined commitment point. Once past the meiotic commitment point in prometaphase I, cells stay committed to meiosis even in the presence of a mitosis-inducing signal. Recent research investigated the maintenance of meiotic commitment in budding yeast and found that two checkpoints that do not normally function in meiosis I, the DNA damage checkpoint and the spindle position checkpoint, have crucial functions in maintaining meiotic commitment. Here, we review these findings and discuss how the mitosis-inducing signal of nutrient-rich medium could activate these two checkpoints in meiosis to prevent inappropriate meiotic exit.
Topics: DNA Damage; Meiosis; Saccharomyces cerevisiae; Spindle Apparatus
PubMed: 31028453
DOI: 10.1007/s00294-019-00981-z -
The Journal of Cell Biology Feb 2019Kinesin-8 is required for proper chromosome alignment in a variety of animal and yeast cell types. However, it is unclear how this motor protein family controls...
Kinesin-8 is required for proper chromosome alignment in a variety of animal and yeast cell types. However, it is unclear how this motor protein family controls chromosome alignment, as multiple biochemical activities, including inconsistent ones between studies, have been identified. Here, we find that kinesin-8 (Klp67A) possesses both microtubule (MT) plus end-stabilizing and -destabilizing activity, in addition to kinesin-8's commonly observed MT plus end-directed motility and tubulin-binding activity in vitro. We further show that Klp67A is required for stable kinetochore-MT attachment during prometaphase in S2 cells. In the absence of Klp67A, abnormally long MTs interact in an "end-on" fashion with kinetochores at normal frequency. However, the interaction is unstable, and MTs frequently become detached. This phenotype is rescued by ectopic expression of the MT plus end-stabilizing factor CLASP, but not by artificial shortening of MTs. We show that human kinesin-8 (KIF18A) is also important to ensure proper MT attachment. Overall, these results suggest that the MT-stabilizing activity of kinesin-8 is critical for stable kinetochore-MT attachment.
Topics: Animals; Cell Line; Drosophila Proteins; Drosophila melanogaster; Humans; Kinesins; Kinetochores; Microtubule-Associated Proteins; Microtubules
PubMed: 30538142
DOI: 10.1083/jcb.201807077 -
BMC Medical Genomics Oct 2020NEK2 has an established involvement in hepatocellular carcinoma (HCC) but the roles of NEK2 and its interacting proteins in HCC have not been systematically explored.
BACKGROUND
NEK2 has an established involvement in hepatocellular carcinoma (HCC) but the roles of NEK2 and its interacting proteins in HCC have not been systematically explored.
METHODS
This study examined NEK2 and its interacting proteins in HCC based on multiple databases.
RESULTS
NEK2 mRNA was highly expressed in HCC tissues compared with normal liver tissues. The survival of HCC patients with high NEK2 mRNA expression was shorter than those with low expression. MAD1L1, CEP250, MAPK1, NDC80, PPP1CA, PPP1R2 and NEK11 were the interacting proteins of NEK2. Among them, NDC80 and CEP250 were the key interacting proteins of NEK2. Mitotic prometaphase may be the key pathway that NEK2 and its interacting proteins contributed to HCC pathogenesis. NEK2, NDC80 and CEP250 mRNAs were highly expressed in HCC tissues compared with normal liver tissues. The mRNA levels of NEK2 were positively correlated with those of NDC80 or CEP250. Univariate regression showed that NEK2, NDC80 and CEP250 mRNA expressions were significantly associated with HCC patients' survival. Multivariate regression showed that NDC80 mRNA expression was an independent predictor for HCC patients' survival. Methylations and genetic alterations of NEK2, NDC80 and CEP250 were observed in HCC samples. The alterations of NEK2, NDC80 and CEP250 genes were co-occurrence. Patients with high mRNA expression and genetic alterations of NEK2, NDC80 and CEP250 had poor prognosis.
CONCLUSIONS
NEK2 and its interacting proteins NDC80 and CEP250 play important roles in HCC development and progression and thus may be potentially used as biomarkers and therapeutic targets of HCC.
Topics: Autoantigens; Biomarkers, Tumor; Carcinoma, Hepatocellular; Case-Control Studies; Cell Cycle Proteins; Cytoskeletal Proteins; Female; Follow-Up Studies; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Male; NIMA-Related Kinases; Prognosis; Protein Interaction Domains and Motifs; Survival Rate
PubMed: 33109182
DOI: 10.1186/s12920-020-00812-y -
Frontiers in Oncology 2022Breast cancer (BRCA) has become the most frequently appearing, lethal, and aggressive cancer with increasing morbidity and mortality. Previously, it was discovered that...
BACKGROUND
Breast cancer (BRCA) has become the most frequently appearing, lethal, and aggressive cancer with increasing morbidity and mortality. Previously, it was discovered that the HAUS5 protein is involved in centrosome integrity, spindle assembly, and the completion of the cytoplasmic division process during mitosis. By encouraging chromosome misdivision and aneuploidy, HAUS5 has the potential to cause cancer. The significance of HAUS5 in BRCA and the relationship between its expression and clinical outcomes or immune infiltration remains unclear.
METHODS
Pan-cancer was analyzed by TIMER2 web and the expression differential of HAUS5 was discovered. The prognostic value of HAUS5 for BRCA was evaluated with KM plotter and confirmed with Gene Expression Omnibus (GEO) dataset. Following that, we looked at the relationship between the high and low expression groups of HAUS5 and breast cancer clinical indications. Signaling pathways linked to HAUS5 expression were discovered using Gene Set Enrichment Analysis (GSEA). The relative immune cell infiltrations of each sample were assessed using the CIBERSORT algorithm and ESTIMATE method. We evaluated the Tumor Mutation Burden (TMB) value between the two sets of samples with high and low HAUS5 expression, as well as the differences in gene mutations between the two groups. The proliferation changes of BRCA cells after knockdown of HAUS5 were evaluated by fluorescence cell counting and colony formation assay.
RESULT
HAUS5 is strongly expressed in most malignancies, and distinct associations exist between HAUS5 and prognosis in BRCA patients. Upregulated HAUS5 was associated with poor clinicopathological characteristics such as tumor T stage, ER, PR, and HER2 status. mitotic prometaphase, primary immunodeficiency, DNA replication, cell cycle related signaling pathways were all enriched in the presence of elevated HAUS5 expression, according to GSEA analysis. The BRCA microenvironment's core gene, HAUS5, was shown to be related with invading immune cell subtypes and tumor cell stemness. TMB in the HAUS5-low expression group was significantly higher than that in the high expression group. The mutation frequency of 15 genes was substantially different in the high expression group compared to the low expression group. BRCA cells' capacity to proliferate was decreased when HAUS5 was knocked down.
CONCLUSION
These findings show that HAUS5 is a positive regulator of BRCA progression that contributes to BRCA cells proliferation. As a result, HAUS5 might be a novel prognostic indicator and therapeutic target for BRCA patients.
PubMed: 35280773
DOI: 10.3389/fonc.2022.829777 -
Current Oncology (Toronto, Ont.) Nov 2022Kruppel-associated box (KRAB) proteins reportedly play a dual role in neoplastic transformation. At present, little is known about the function of the proteins encoded...
OBJECTIVE
Kruppel-associated box (KRAB) proteins reportedly play a dual role in neoplastic transformation. At present, little is known about the function of the proteins encoded by the human pogo transposable element derived with KRAB domain (POGK) gene. Herein, we evaluated the prognostic significance of POGK expression in patients with hepatocellular carcinoma (HCC).
METHODS
The data of HCC patients was downloaded from The Cancer Genome Atlas (TCGA) database. To determine the relationship between POGK and clinical features, logistic regression was applied. Cox regression and Kaplan-Meier analyses were used to evaluate the correlation between POGK and survival rates. Gene ontology (GO) analysis and Gene set enrichment analysis (GSEA) were conducted to identify the enriched pathways and functions associated with POGK.
RESULTS
A total of 374 HCC patients were identified in TCGA. POGK was significantly upregulated in HCC and correlated with tumor status ( = 0.036), race ( = 0.025), weight ( = 0.002), body mass index ( = 0.033), histologic grade ( < 0.001), and alpha-fetoprotein ( < 0.001). High POGK expression in HCC patients correlated with a poor outcome in terms of overall survival ( = 0.0018), progression-free survival ( = 0.0087), relapse-free survival ( = 0.045), and disease-specific survival ( = 0.014), according to Kaplan-Meier analysis. Receiver operating characteristic curve analysis showed that the area under the curve of POGK expression for HCC diagnosis was 0.891. GSEA showed that high POGK expression might activate mitotic prometaphase, kinesins, homologous DNA pairing and strand exchange, MET activates PTK2 signaling pathway, G1 to S cell cycle control, Aurora B pathway, ncRNAs involved in WNT signaling pathway, hepatitis C, and ncRNAs involved in the STAT3 signaling pathway. POGK expression correlated with the abundance of adaptive and innate immunocytes in HCC.
CONCLUSION
High expression of POGK has high diagnostic and prognostic values in patients with HCC. Moreover, POGK expression is correlated with immune infiltration in HCC.
Topics: Humans; Carcinoma, Hepatocellular; Liver Neoplasms; Gene Expression Regulation, Neoplastic; Biomarkers, Tumor; Neoplasm Recurrence, Local; Prognosis
PubMed: 36421335
DOI: 10.3390/curroncol29110682