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Abstract: A series of pyrrolopyridinone derivatives as specific inhibitors towards the cell division cycle 7 (Cdc7) was taken into account, and the efficacy of these compounds was analyzed by QSAR and docking approaches to gain deeper insights into the interaction mechanism and ligands selectivity for Cdc7. By regression analysis the prediction models based on Grid score and Zou-GB/SA score were found, respectively with good quality of fits (r 2 =0.748, 0.951; , 0.839). The accuracy of the models was validated by test set and the deviation of the predicted values in validation set using Zou-GB/SA score was smaller than that using Grid score, suggesting that the model based on Zou-GB/SA score provides a more effective method for predicting potencies of Cdc7 inhibitors. [Copyright &y& Elsevier]

Highlights: [•] This report first mentions that Cdc7-Dbf4 is overexpressed in oral cancer. [•] Cdc7 expression is significantly associated with poor outcome of OSCC patients. [•] Cdc7 expression is an independent prognosis factor for overall survival of OSCC patients. [•] Overexpressed Cdc7 enhances the resistance to chemotherapy using DNA-damaging agents. [Copyright &y& Elsevier]

Diffuse large B-cell lymphoma (DLBCL) is the most common form of lymphoma. According to the clinical risk factors and biological heterogeneity, clinical outcome of DLBCL is extremely various, with 5-year survival rates between 30 and 80 %. Although the International Prognostic Index (IPI) remains the primary clinical tool used to predict outcome for patients with DLBCL, notable variability in outcome is still observed within the same IPI score. The cell division cycle 7 (CDC7) is a serine-threonine kinase, which is required to initiate DNA replication. Study showed that high expression of CDC7 was correlated with poor prognosis in patients with DLBCL. Whether CDC7 is an independent prognostic factor for DLBCL remains debatable. We studied the expression of CDC7 protein in 60 Chinese DLBCL patients with immunohistochemical analysis, 34 patients (56.7 %) categorized as low CDC7 expression and 26 patients (43.3 %) as high CDC7 expression. The median survival time of patients with low CDC7 expression was not achieved and that of high expression was 9 months ( P = 0.027). A multivariate analysis showed that IPI score and Ann Arbor stage were independent prognostic factors in relation to patients' OS ( P < 0.05). Pearson correlation analysis showed that CDC7 expression level was positively correlated with IPI score and Ann Arbor stage ( P < 0.001). The results suggest that CDC7 expression level in combination with IPI score and Ann Arbor stage can be specific prognostic factors for DLBCL patients. CDC7 could also be a potential therapeutic target in DLBCL, especially for ABC-DLBCL. [ABSTRACT FROM AUTHOR]

Background: The cell division cycle 7 (CDC7) is a serine-threonine kinase, which is required for DNA replication and is high expressed in diffuse large B cell lymphoma (DLBCL). Methods: In this study, we targeted CDC7 in human DLBCL-ABC subtype cells (ly3) and examined the subsequent alterations in cellular apoptosis. The expression of CDC7 was silenced with small interfering RNA (siRNA)-expressing plasmid. CDC7 gene silencing cells were then incubated with or without rituximab for 24 h. Following treatment, Annexin V/propidium iodide staining followed by flow cytometry was used to examine cellular apoptosis. Furthermore, the expression of caspase 3, Bax, and Bcl-2 protein was analyzed by Western blotting. The expression of Bax and Bcl-2 mRNA was analyzed by quantitative real-time PCR. Results: Compared to non-treated or control siRNA-transfected cells, significantly higher levels of apoptosis were detected in siCDC7-transfected cells and rituximab-treated cells ( P < 0.05), which was further enhanced in CDC7-targeted cells with rituximab treatment ( P < 0.05). The pro-apoptotic effects were accompanied with up-regulation of caspase 3 and Bax, meanwhile down-regulation of Bcl-2. Conclusion: Combined treatments using rituximab and CDC7 gene silencing significantly increases apoptosis in ly3 cells and plays synergistic effect. CDC7 is a novel therapeutic target in DLBCL patients. CDC7 inhibitors combined with rituximab will be the new therapy for the ABC-DLBCL patients. [ABSTRACT FROM AUTHOR]

Development of a fertilized human egg into an average sized adult requires about 29 trillion cell divisions, thereby producing enough DNA to stretch to the Sun and back 200 times (DePamphilis and Bell, 2011)! Even more amazing is the fact that throughout these mitotic cell cycles, the human genome is duplicated once and only once each time a cell divides. If a cell accidentally begins to re-replicate its nuclear DNA prior to cell division, checkpoint pathways trigger apoptosis. And yet, some cells are developmentally programmed to respond to environmental cues by switching from mitotic cell cycles to endocycles, a process in which multiple S phases occur in the absence of either mitosis or cytokinesis. Endocycles allow production of viable, differentiated, polyploid cells that no longer proliferate. What is surprising is that among the 516 (Manning et al., 2002) to 557 (BioMart web site) protein kinases encoded by the human genome, only eight regulate nuclear DNA replication directly. These are Cdk1, Cdk2, Cdk4, Cdk6, Cdk7, Cdc7, Checkpoint kinase-1 (Chk1), and Checkpoint kinase-2. Even more remarkable is the fact that only four of these enzymes (Cdk1, Cdk7, Cdc7, and Chk1) are essential for mammalian development. Here we describe how these protein kinases determine when DNA replication occurs during mitotic cell cycles, how mammalian cells switch from mitotic cell cycles to endocycles, and how cancer cells can be selectively targeted for destruction by inducing them to begin a second S phase before mitosis is complete. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the SAR of a series of pyrimidinone-containing Cdc7 kinase inhibitors. A wide range of amine substitutions give potent compounds with activities (K i) less than 1nM. Kinase selectivity is reasonable and cytotoxicity corresponds to inhibition of MCM2 phosphorylation. [Copyright &y& Elsevier]

DNA replication starts at initiation sites termed replication origins. Metazoan cells contain many more potential origins than are activated (fired) during each S phase. Origin activation is controlled by the ATR checkpoint kinase and its downstream effector kinase Chk1, which suppresses origin firing in response to replication blocks and during normal S phase by inhibiting the cyclin-dependent kinase Cdk2. In addition to increased origin activation, cells deficient in Chk1 activity display reduced rates of replication fork progression. Here we investigate the causal relationship between increased origin firing and reduced replication fork progression. We use the Cdk inhibitor roscovitine or RNAi depletion of Cdc7 to inhibit origin firing in Chk1-inhibited or RNAi-depleted cells. We report that Cdk inhibition and depletion of Cdc7 can alleviate the slow replication fork speeds in Chk1-deficient cells. Our data suggest that increased replication initiation leads to slow replication fork progression and that Chk1 promotes replication fork progression during normal S phase by controlling replication origin activity. [ABSTRACT FROM AUTHOR]

Summary: Cell division cycle 7 is a widely expressed protein kinase implicated in cell division, cell cycle checkpoint mechanisms, and cancer progression. To determine the relationship of cell division cycle 7 protein expression with tumor phenotype, molecular features and prognosis, 2197 highly characterized breast carcinomas were analyzed on a tissue microarray. Detectable cell division cycle 7 expression was found in 1088 (57%) of breast cancer specimens and 228 (11.9%) exhibited a moderate or strong expression. High levels of cell division cycle 7 expression were significantly related to medullary histotype (P < .0001); high tumor grade (P < .0001); negative estrogen receptor status (P < .0001); high Ki67 expression level (P < .0001); p53 and p16 overexpression (P < .0001); and amplification of HER2 (P < .0001), c-myc (P < .0001), MDM2 (P = .043), CCND1 (P = .0084), and ESR1 (P = .0012) as well as with the number of amplified genes (P < .0001). There was also a tendency towards worse prognosis in cell division cycle 7 positive as compared to negative breast cancers. The relationship between cell division cycle 7 and number of amplifications was independent from tumor proliferation raising the possibility of a direct influence of cell division cycle 7 expression for amplification development. In conclusion, cell division cycle 7 is a replication associated protein with relationships to gene amplification and genomic instability in breast carcinomas. These data support the potential utility of newly developed small molecule cell division cycle 7 inhibitors as a therapeutic alternative in at least a subset of breast carcinomas. [Copyright &y& Elsevier]

HKH40A (RTA 502), an optimized 8-methoxy analog of the unsymmetrical bifunctional antitumor agent WMC79, was found to be potently active against liver cancer cell growth in vitro and in vivo. Studies on selected human hepatocellular carcinoma (HCC) cell lines with differing p53 status (HepG2, Hep3B, and PLC/PRF/5), revealed that drug-mediated growth inhibition was independent of p53 status. FACS analysis showed an accumulation of cells in S-phase within 24 h of treatment with 100 nM HKH40A. Subsequent incubation of cells, either in the presence of drug or without, caused cell cycle block at the S and G2/M checkpoints, which was consistent with the observed up-regulation of p21, cyclin A, cyclin B1, sustained phosphorylation of Cdk1, and down-regulation of Cdc6, Cdc7, and RRM2. This irreversible growth arrest eventually led to apoptosis. HKH40A completely suppressed growth of the rat transplantable HCC cell line (JM-1) in an orthotopic model in Fisher 344 rats in vivo, without evidence of toxicity. HKH40A may be a useful agent for new therapeutic strategies focusing on inhibition of HCC cell proliferation. [ABSTRACT FROM AUTHOR]

Abstract: A series of 4-(4-hydroxyphenyl)-6-phenylpyrimidin-2(1H)-ones were identified by HTS as inhibitors of CDC7. Molecular modeling and medicinal chemistry techniques were employed to explore the SAR for this series with a focus on removing potential metabolic liabilities and improving cellular potency. [Copyright &y& Elsevier]

Abstract: CR/periphilin (CR) retards cell cycle progression mainly at the S-phase in part by transcriptionally repressing expression of Cdc7, the key regulator of DNA replication, and in part by unknown mechanisms. In this study, we show that enforced expression of CR inhibits Cdc7 promoter activity. The attachment of the DNA-binding domain of the yeast GAL4 transcription factor to CR that appears without DNA-binding sequences, enables CR to repress GAL4 promoter-mediated transcription in a histone deacetylase (HDAC) activity-dependent manner. CR forms a complex with mSin3A, a common component in transcriptional repressor complexes, as well as with HDAC1, suggesting that CR may behave as a co-repressor by functional interaction with the Sin3/HDAC co-repressor complex. We also demonstrate that an alternatively spliced variant of CR, CR-S, which is without a region encoded by exon 4 of the CR gene and is a weak interactor with HDAC1, shows a suppressing effect on CR activity. [Copyright &y& Elsevier]

Abstract: Cdc7-Dbf4 serine/threonine kinase is essential for initiation of DNA replication. It was previously found that overexpression of certain replication proteins such as Cdc6 and Cdt1 in fission yeast resulted in multiple rounds of DNA replication in the absence of mitosis. Since this phenomenon is dependent upon the presence of wild-type Cdc7/Hsk1, we hypothesized that high levels of Cdc7 and/or Dbf4 could also cause multiple rounds of DNA replication, or could facilitate entry into S phase. To test this hypothesis, we transiently overexpressed hamster Cdc7, Dbf4 or both in CHO cells. Direct observations of individual cells by fluorescence microscopy and flow cytometric analysis on cell populations suggest that overexpression of Cdc7 and/or Dbf4 does not result in multiple rounds of DNA replication or facilitating entry into S phase. In contrast, moderately increased levels of Dbf4, but not Cdc7, cause cell-cycle arrest in G2/M. This G2/M arrest coincides with hyperphosphorylation of Cdc2/Cdk1 at Tyr-15, raising the possibility that high levels of Dbf4 may activate a G2/M cell-cycle checkpoint. Further increase in Cdc7 and/or Dbf4 by 2–4 fold can arrest cells in G1 and significantly slow down S-phase progression for the cells already in S phase. [Copyright &y& Elsevier]

Cdc7, a protein kinase required for the initiation of eukaryotic DNA replication, is activated by a regulatory subunit, Dbf4. A second activator of Cdc7 called Drf1 exists in vertebrates, but its function is unknown. Here, we report that in Xenopus egg extracts, Cdc7-Drf1 is far more abundant than Cdc7-Dbf4, and removal of Drf1 but not Dbf4 severely inhibits phosphorylation of Mcm4 and DNA replication. After gastrulation, when the cell cycle acquires somatic characteristics, Drf1 levels decline sharply and Cdc7-Dbf4 becomes the more abundant kinase. These results identify Drf1 as a developmentally regulated, essential activator of Cdc7 in Xenopus. [ABSTRACT FROM AUTHOR]

Cdc7 expression repressor (CR)/periphilin has been originally cloned as an interactor with periplakin, a precursor of the cornified cell envelope, and suggested to constitute a new type of nuclear matrix. We here show that CR/periphilin is a ubiquitously expressed nuclear protein with speckled distribution. Overexpression of CR/periphilin induces S-phase arrest. Analysis of expression of regulators involved in DNA replication has revealed that both mRNA and protein expression of Cdc7, a regulator of the initiation and continuation of DNA replication, are markedly downregulated by overexpression of CR/periphilin. However, co-expression of Cdc7 only marginally rescues S-phase arrest induced by CR, indicating that CR retards S-phase progression by modifying expression of some genes including Cdc7, which are involved in progression of DNA replication or coordination of DNA replication and S-phase progression. [Copyright &y& Elsevier]

We report the identification of a novel Cdc25-like protein phosphatase, Ibp1, in the fission yeast Schizosaccharomyces pombe. Ibp1 is closely related to the catalytic subunit of the Cdc25 dual-specificity phosphatases and has phosphatase activity in vitro. Over-production of catalytically active Ibp1 robustly suppresses a mutation in the replication initiation kinase Hsk1p, a member of the Cdc7 family of protein kinases and weakly suppresses mutation of Rad4/Cut5, a DNA polymerase ε-associated factor. Ibp1 is not required for viability, suggesting it may be a non-essential regulator of DNA replication or chromosome structure during S phase. [ABSTRACT FROM AUTHOR]

Studies in model organisms have contributed to elucidate multiple levels at which regulation of eukaryotic DNA replication occurs. Cdc7, an evolutionarily conserved serine–threonine kinase, plays a pivotal role in linking cell cycle regulation to genome duplication, being essential for the firing of DNA replication origins. Binding of the cell cycle‐regulated subunit Dbf4 to Cdc7 is necessary for in vitro kinase activity. This binding is also thought to be the key regulatory event that controls Cdc7 activity in cells. Here, we describe a novel human protein, Drf1, related to both human and yeast Dbf4. Drf1 is a nuclear cell cycle‐regulated protein, it binds to Cdc7 and activates the kinase. Therefore, human Cdc7, like cyclin‐dependent kinases, can be activated by alternative regulatory subunits. Since the Drf1 gene is either absent or not yet identified in the genome of model organisms such as yeast and Drosophila, these findings introduce a new level of complexity in the regulation of DNA replication of the human genome. [ABSTRACT FROM AUTHOR]

Summary We identified an Arabidopsis thaliana gene, AtMAP3Kε1, and a Brassica napus cDNA, BnMAP3Kε1, encoding functional protein serine/threonine kinases closely related to cdc7p and Cdc15p from Schizosaccharomyces pombe and Saccharomyces cerevisiae, respectively. This is the first report of cdc7-related genes in non-fungal eukaryotes; no such genes have as yet been identified in Metazoans. The B. napus protein is able to partially complement a cdc7 loss of function mutation in S. pombe. RT–PCR and in situ hybridisation revealed that the A. thaliana and B. napus genes are expressed in both the sporophytic and the gametophytic tissues of the respective plant species and revealed further that expression is highest in dividing cells. Moreover, AtMAP3Kε1 gene expression is cell cycle-regulated, with higher expression in G2-M phases. Our results strongly suggest that the plant cdc7p-related protein kinases are involved in a signal transduction pathway similar to the SIN pathway, which positively regulates cytokinesis in S. pombe. [ABSTRACT FROM AUTHOR]

Coordination of mitosis and cytokinesis is crucial for ensuring proper chromosome segregation and genomic stability. In Schizosaccharomyces pombe, the sid genes (cdc7, cdc11, cdcl4, spgl, sid1, sid2 and sid4) define a signaling pathway that regulates septation and cytokinesis. Here we describe the characterization of a novel protein kinase, Sid1p. Sid1p localizes asymmetrically to one spindle pole body (SPB) in anaphase. Sid1p localization is maintained during medial ring constriction and septum synthesis and disappears prior to cell separation. Additionally, we found that Cdcl4p is in a complex with Sid1p. Epistasis analysis places Sid1p-Cdcl4p downstream of Spg1p-Cdc7p but upstream of Sid2p. Finally, we show that cyclin proteolysis during mitosis is unaffected by inactivating the sid pathway; in fact, loss of Cdc2-cyclin activity promotes Sid1p-Cdcl4p association with the SPB, possibly providing a mechanism that couples cytokinesis with mitotic exit. [ABSTRACT FROM AUTHOR]

Ewing sarcoma is an aggressive childhood cancer for which treatment options remain limited and toxic. There is an urgent need for the identification of novel therapeutic strategies. Our group has recently shown that Ewing cells rely on the S-phase kinase CDC7 (DDK) to maintain replication rates and cell viability and that DDK inhibition causes an increase in the phosphorylation of CDK1 and a significant delay in mitotic entry. Here, we expand on our previous findings and show that DDK inhibitor-induced mitotic entry delay is dependent upon WEE1 kinase. Specifically, WEE1 phosphorylates CDK1 and prevents mitotic entry upon DDK inhibition due to the presence of under-replicated DNA, potentially limiting the cytotoxic effects of DDK inhibition. To overcome this, we combined the inhibition of DDK with the inhibition of WEE1 and found that this results in elevated levels of premature mitotic entry, mitotic catastrophe, and apoptosis. Importantly, we have found that DDK and WEE1 inhibitors display a synergistic relationship with regards to reducing cell viability of Ewing sarcoma cells. Interestingly, the cytotoxic nature of this combination can be suppressed by the inhibition of CDK1 or microtubule polymerization, indicating that mitotic progression is required to elicit the cytotoxic effects. This is the first study to display the potential of utilizing the combined inhibition of DDK and WEE1 for the treatment of cancer. We believe this will offer a potential therapeutic strategy for the treatment of Ewing sarcoma as well as other tumor types that display sensitivity to DDK inhibitors., Competing Interests: Conflict of Interest: The authors declare no potential conflicts of interest.

A population pharmacokinetic (PK) analysis was conducted to characterize sources of interpatient variability on the PK of TAK-931, a cell division cycle 7 kinase inhibitor, in adult patients with advanced solid tumors using data from 198 patients who received oral TAK-931 over the range of 30 to 150 mg once daily in multiple dosing schedules in 2 phase 1 and 1 phase 2 clinical studies. A 2-compartment model with 2 transit compartments describing the absorption and first-order linear elimination adequately described the PK of TAK-931. The apparent oral clearance (CL/F) of TAK-931 was estimated to be 38 L/h, and the terminal half-life was estimated to be approximately 6 hours. Creatinine clearance (CrCL) was identified as a covariate on CL/F, and body weight as a covariate on CL/F, apparent central volume of distribution, and apparent intercompartmental clearance. Simulations using the final model indicated that the effect of CrCL (≥35 mL/min) or body weight (29.8-127 kg) on TAK-931 systemic exposures was not considered clinically meaningful, suggesting that no dose adjustments were necessary to account for body weight or renal function (CrCL ≥35 mL/min). Sex, age (36-88 years), race, and mild hepatic impairment had no impact on the CL/F of TAK-931. Taken together, the population PK analysis supports the same starting dose of TAK-931 in Asian and Western cancer patients in a global setting., (© 2021 Millennium Pharmaceuticals, Inc. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

The minichromosome maintenance (MCM) helicase physically interacts with the recombination proteins Rad51 and Rad52 from yeast to human cells. We show, in Saccharomyces cerevisiae , that these interactions occur within a nuclease-insoluble scaffold enriched in replication/repair factors. Rad51 accumulates in a MCM- and DNA-binding-independent manner and interacts with MCM helicases located outside of the replication origins and forks. MCM, Rad51, and Rad52 accumulate in this scaffold in G1 and are released during the S phase. In the presence of replication-blocking lesions, Cdc7 prevents their release from the scaffold, thus maintaining the interactions. We identify a rad51 mutant that is impaired in its ability to bind to MCM but not to the scaffold. This mutant is proficient in recombination but partially defective in single-stranded DNA (ssDNA) gap filling and replication fork progression through damaged DNA. Therefore, cells accumulate MCM/Rad51/Rad52 complexes at specific nuclear scaffolds in G1 to assist stressed forks through non-recombinogenic functions. [Display omitted] • Rad51 and Rad52 interact with MCM in a nuclease-insoluble nucleoprotein scaffold • MCM/Rad51/Rad52 accumulation is regulated by cell cycle and replicative DNA damage • Cdc7 prevents Rad51/Rad52 release from the scaffold under replicative DNA damage • MCM/Rad51 promotes MMS-induced gap filling and fork progression by non-HR processes Cabello-Lobato et al. find that MCM interacts dynamically with Rad51 and Rad52 within a nuclease-insoluble nucleoprotein scaffold. These interactions are established in G1 and maintained in the S phase by Cdc7 in the presence of replication-blocking lesions to assist stressed forks through non-recombinogenic functions. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae Cdc7 kinase is essential for initiation of DNA replication, and Hsk1, a related kinase of Schizosaccharomyces pombe, is also required for DNA replication of fission yeast cells. We report here cDNAs encoding Cdc7-related kinases from human and Xenopus (huCdc7 and xeCdc7, respectively). The cloned cDNA for huCdc7 contains an open reading frame consisting of 574 amino acids with a predicted molecular weight of 63 847 that possesses overall amino acid identity of 32% (54% including similar residues) to Cdc7 and Hsk1. huCDC7 is transcribed in the various tissues examined, but most abundantly in testis. Three transcripts of 4.4, 3.5 and 2.4 kb in length are detected. The 3.5 kb transcript is the most predominant and is expressed in all the tissues examined. A cDNA containing a 91 nucleotide insertion at the N-terminal region of huCDC7 is also detected, suggesting the presence of multiple splicing variants. The huCdc7 protein is expressed at a constant level during the mitotic cell cycle and is localized primarily in nuclei in interphase and distributed diffusibly in cytoplasm in the mitotic phase. The wild-type huCdc7 protein expressed in COS7 cells phosphorylates MCM2 and MCM3 proteins in vitro, suggesting that huCdc7 may regulate processes of DNA replication by modulating MCM functions. [ABSTRACT FROM AUTHOR]

CDC7 is an essential Ser/Thr kinase that acts upon the replicative helicase throughout the S phase of the cell cycle and is activated by DBF4. Here, we present crystal structures of a highly active human CDC7-DBF4 construct. The structures reveal a zinc-finger domain at the end of the kinase insert 2 that pins the CDC7 activation loop to motif M of DBF4 and the C lobe of CDC7. These interactions lead to ordering of the substrate-binding platform and full opening of the kinase active site. In a co-crystal structure with a mimic of MCM2 Ser40 phosphorylation target, the invariant CDC7 residues Arg373 and Arg380 engage phospho-Ser41 at substrate P+1 position, explaining the selectivity of the S-phase kinase for Ser/Thr residues followed by a pre-phosphorylated or an acidic residue. Our results clarify the role of DBF4 in activation of CDC7 and elucidate the structural basis for recognition of its preferred substrates. • DBF4 activates CDC7 kinase via a two-step mechanism • Zinc-finger domain in CDC7 KI2 interacts with DBF4 motif M • Invariant CDC7 residues Arg373 and Arg380 engage P+1 substrate site CDC7 is a protein kinase that is essential for cell division. Using X-ray crystallography, Cherepanov and colleagues explain the two-step mechanism of CDC7 activation by its dedicated regulator protein DBF4. They also identify amino acid residues in CDC7 that are crucial for the recognition of its preferred substrates. [ABSTRACT FROM AUTHOR]

Eukaryotic genomes replicate via spatially and temporally regulated origin firing. Cyclin-dependent kinase (CDK) and Dbf4-dependent kinase (DDK) promote origin firing, whereas the S phase checkpoint limits firing to prevent nucleotide and RPA exhaustion. We used chemical genetics to interrogate human DDK with maximum precision, dissect its relationship with the S phase checkpoint, and identify DDK substrates. We show that DDK inhibition (DDKi) leads to graded suppression of origin firing and fork arrest. S phase checkpoint inhibition rescued origin firing in DDKi cells and DDK-depleted Xenopus egg extracts. DDKi also impairs RPA loading, nascent-strand protection, and fork restart. Via quantitative phosphoproteomics, we identify the BRCA1-associated (BRCA1-A) complex subunit MERIT40 and the cohesin accessory subunit PDS5B as DDK effectors in fork protection and restart. Phosphorylation neutralizes autoinhibition mediated by intrinsically disordered regions in both substrates. Our results reveal mechanisms through which DDK controls the duplication of large vertebrate genomes., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Introduction: Cell division cycle-7 protein is a serine/threonine kinase that has a basic role in cell cycle regulation and is a potential prognostic or therapeutic target in some human cancers., Objectives: This study investigated the expression of cell division cycle-7 protein in benign and malignant salivary gland tumors and also its correlation with clinicopathologic factors., Methods: Immunohistochemical expression of cell division cycle-7 was evaluated in 46 cases, including 15 adenoid cystic carcinoma, 12 mucoepidermoid carcinoma, 14 pleomorphic adenoma, and 5 normal salivary glands. Cell division cycle-7 expression rate and intensity were compared statistically., Results: The protein was expressed in almost all tumors. The intensity and mean of cell division cycle-7 expression were higher in malignant tumors in comparison with pleomorphic adenomas (p=0.000). The protein expression was correlated with tumor grades (p=0.000)., Conclusions: The present study demonstrated cell division cycle-7 overexpression in malignant salivary gland tumors in comparison with pleomorphic adenomas, and also a correlation with tumor differentiation. Therefore, this protein might be a potential prognostic and therapeutic target for salivary gland tumors., (Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.)

Summary DNA replication is initiated by assembly of the kinase cell division cycle 7 (CDC7) with its regulatory activation subunit, activator of S-phase kinase (ASK), to activate DNA helicase. However, the mechanism underlying regulation of CDC7-ASK complex is unclear. Here, we show that ADP generated from CDC7-mediated MCM phosphorylation binds to an allosteric region of CDC7, disrupts CDC7-ASK interaction, and inhibits CDC7-ASK activity in a feedback way. EGFR- and ERK-activated casein kinase 2α (CK2α) phosphorylates nuclear phosphoglycerate kinase (PGK) 1 at S256, resulting in interaction of PGK1 with CDC7. CDC7-bound PGK1 converts ADP to ATP, thereby abrogating the inhibitory effect of ADP on CDC7-ASK activity, promoting the recruitment of DNA helicase to replication origins, DNA replication, cell proliferation, and brain tumorigenesis. These findings reveal an instrumental self-regulatory mechanism of CDC7-ASK activity by its kinase reaction product ADP and a nonglycolytic role for PGK1 in abrogating this negative feedback in promoting tumor development. Graphical Abstract Highlights • ADP generated from CDC7-mediated phosphorylation inhibits CDC7-ASK activity • EGFR- and ERK1/2-dependent activation of CK2α phosphorylates PGK1 at S256 • Phosphorylated PGK1 binds to CDC7 and converts ADP to ATP • PGK1 releases ADP's inhibition on CDC7 to promote DNA replication and tumorigenesis Li et al. demonstrate that ADP generated from CDC7-mediated MCM phosphorylation binds to an allosteric region of CDC7, disrupts CDC7-ASK interaction, and inhibits CDC7-ASK activity in a feedback way. CDC7-bound PGK1 under EGFR activation condition converts ADP to ATP, thereby abrogating ADP's inhibition on CDC7-ASK activity and promoting DNA replication. [ABSTRACT FROM AUTHOR]