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Abstract In the context of globalization, the integration of cultural elements into scientific research, particularly through the incorporation of traditional Chinese cultural motifs in scientific illustrations, represents a novel frontier in enhancing the universality and appeal of scientific discoveries. This paper explores the innovative practice of embedding traditional Chinese cultural elements into scientific paper illustrations, highlighting its significant role in augmenting the global appeal of research findings, promoting diversity and innovation in scientific inquiry, and facilitating cross-cultural understanding. Through a series of case studies, including symbolic representations of ancient myths and the use of traditional themes to elucidate complex scientific phenomena, we demonstrate how this cultural integration not only makes scientific content more accessible and engaging but also fosters a deeper appreciation of Chinese heritage among international audiences. This approach not only bridges the gap between science and culture but also contributes to a more inclusive and interconnected global scientific community, underscoring the importance of cultural diversity in enriching scientific exploration and communication.

Abstract Background MicroRNAs (miRNAs), as an indispensable type of non-coding RNA (ncRNA), participate in diverse biological processes. However, the specific regulatory mechanism of certain miRNAs in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Methods The expression of miR-194-5p in PDAC tissue microarray and cell lines were detected by RNA-scope and real-time quantitative PCR (RT-qPCR). The function of proliferation and migration carried by miR-194-5p in vitro and vivo was observed by several functional experiments. Informatics methods and RNA sequencing data were applied to explore the target of miR-194-5p and the upstream circular RNA (circRNA) of miR-194-5p. RNA-binding protein immunoprecipitation (RIP) assay and dual-luciferase reporter assay confirmed the relationships between miR-194-5p and SOCS2 or miR-194-5p and circPVRL3. The proliferation and migration abilities of SOCS2 and circPVRL3 were accessed by rescue experiments. Results In this study, we aimed to clarify the molecular mechanisms of miR-194-5p, which has critical roles during PDAC progression. We found that the expression of miR-194-5p was significantly upregulated in PDAC tissue compared to tumor-adjacent tissue and was highly related to age and nerve invasion according to RNAscope and RT‒qPCR. Overexpression of miR-194-5p accelerated the cell cycle and enhanced the proliferation and migration processes according to several functional experiments in vitro and in vivo. Specifically, circPVRL3, miR-194-5p, and SOCS2 were confirmed to work as competing endogenous RNAs (ceRNAs) according to informatics methods, RIP, and dual-luciferase reporter assays. Additionally, the rescue experiments confirmed the relationship among miR-194-5p, circPVRL3, and SOCS2 mRNA. Finally, the circPVRL3/miR-194-5p/SOCS2 axis activates the PI3K/AKT signaling pathway to regulate the proliferation and metastasis of PDAC. Conclusion Our findings indicated that an increase of miR-194-5p caused by circPVRL3 downregulation stimulates the PI3K/AKT signaling pathway to promote PDAC progression via the circPVRL3/miR-194-5p/SOCS2 axis, which suggests that the circPVRL3/miR-194-5p/SOCS2 axis may be a potential therapeutic target for PDAC patients.

Abstract Background Although gemcitabine has been considered as the first-line drug for advanced pancreatic cancer (PC), development of resistance to gemcitabine severely limits the effectiveness of this chemotherapy, and the underlying mechanism of gemcitabine resistance remains unclear. Various factors, such as ATP binding cassette (ABC) transporters, microRNAs and their downstream signaling pathways are included in chemoresistance to gemcitabine. This study investigated the potential mechanisms of microRNAs and ABC transporters related signaling pathways for PC resistance to gemcitabine both in vivo and in vitro. Methods Immunohistochemistry and Western blotting were applied to detect the expression of ABC transporters. Molecular docking analysis was performed to explore whether gemcitabine interacted with ABC transporters. Gain-of-function and loss-of-function analyses were performed to investigate the functions of hsa-miR-3178 in vitro and in vivo. Bioinformatics analysis, Western blotting and dual-luciferase reporter assay were used to confirm the downstream regulatory mechanisms of hsa-miR-3178. Results We found that P-gp, BCRP and MRP1 were highly expressed in gemcitabine-resistant PC tissues and cells. Molecular docking analysis revealed that gemcitabine can bind to the ABC transporters. Hsa-miR-3178 was upregulated in gemcitabine resistance PANC-1 cells as compared to its parental PANC-1 cells. Moreover, we found that hsa-miR-3178 promoted gemcitabine resistance in PC cells. These results were also verified by animal experiments. RhoB was down-regulated in gemcitabine-resistant PC cells and it was a downstream target of hsa-miR-3178. Kaplan–Meier survival curve showed that lower RhoB expression was significantly associated with poor overall survival in PC patients. Rescue assays demonstrated that RhoB could reverse hsa-miR-3178-mediated gemcitabine resistance. Interestingly, hsa-miR-3178 promoted gemcitabine resistance in PC by activating the PI3K/Akt pathway-mediated upregulation of ABC transporters. Conclusions Our results indicate that hsa-miR-3178 promotes gemcitabine resistance via RhoB/PI3K/Akt signaling pathway-mediated upregulation of ABC transporters. These findings suggest that hsa-miR-3178 could be a novel therapeutic target for overcoming gemcitabine resistance in PC.

BackgroundMany studies have reported that N6-methyladenosine (m6A) modification plays a critical role in the epigenetic regulation of organisms and especially in the pathogenesis of malignant diseases. However, m6A research has mainly focused on methyltransferase activity mediated by METTL3, and few studies have focused on METTL16. The aim of this study was to investigate the mechanism of METTL16, which mediates m6A modification, and its role in pancreatic adenocarcinoma (PDAC) cell proliferation.MethodsClinicopathologic and survival data were retrospectively collected from 175 PDAC patients from multiple clinical centers to detect the expression of METTL16. CCK-8, cell cycle, EdU and xenograft mouse model experiments were used to evaluate the proliferation effect of METTL16. Potential downstream pathways and mechanisms were explored via RNA sequencing, m6A sequencing, and bioinformatic analyses. Regulatory mechanisms were studied through methyltransferase inhibition, RIP, MeRIP‒qPCR assays.ResultsWe found that METTL16 expression was markedly downregulated in PDAC, and multivariate Cox regression analyses revealed that METTL16 was a protective factor for PDAC patients. We also demonstrated that METTL16 overexpression inhibited PDAC cell proliferation. Furthermore, we identified a METTL16-p21 signaling axis, with downregulation of METTL16 resulting in inhibition of CDKN1A (p21). Additionally, METTL16 silencing and overexpression experiments highlighted m6A modification alterations in PDAC.ConclusionsMETTL16 plays a tumor-suppressive role and suppresses PDAC cell proliferation through the p21 pathway by mediating m6A modification. METTL16 may be a novel marker of PDAC carcinogenesis and target for the treatment of PDAC.

Abstract Background C-Myc aberrations confer a more aggressive clinic behavior in diffuse large B-cell lymphoma (DLBCL). Matrine is an alkaloid extracted from Sophora flavescens Ait. It possesses anti-cancer property through inhibiting the cell proliferation and inducing the apoptosis. The present study aimed to explore the underlying mechanisms of matrine in suppressing the cell growth of DLBCL. Methods The influence of matrine on the viability of cultured DLBCL cell lines SU-DHL-16 and OCI-LY3 cells were determined by CCK-8. Apoptosis and cell cycle were measured by flow cytometry after matrine exposure. Western blot was taken to investigate the expression of activated Caspase-3, cleaved PARP, c-Myc, phospho-c-Myc (Ser62), CaMKIIγ, phospho-CaMKIIγ (Thr287), CDK4 and CDK6 after matrine treatment. Cycloheximide chase analysis was used to determine the c-Myc protein half-lives before and after matrine treatment. Growth salvage analysis was taken by ectopic expression of c-Myc. Results In cultured DLBCL cells, matrine suppressed cell viability in a concentration and time dependent fashion. Matrine treated SU-DHL-16 and OCI-LY3 cells for 48 h with IC50 value of 1.76 mM and 4.1 mM, respectively. Matrine induced apoptosis through a caspase-independent pathway and caused G0/G1 cell cycle arrest in a concentration dependent manner in DLBCL cells. The protein expression of c-Myc was inhibited while the transcription of c-Myc was not reduced by matrine. c-Myc protein half-lives were decreased from 30.4, 69.4 min to 16.6, 15.9 min after matrine treatment in SU-DHL-16 and OCI-LY3, respectively. As a critical protein kinase of c-Myc, CaMKIIγ phosphorylation at Thr287 was found to be down-regulated and c-Myc phosphorylation at Ser62 was reduced together after matrine treatment in DLBCL. The growth suppression of SU-DHL-16 cells induced by matrine was rescued by over-expression of c-Myc achieved by recombinant adenovirus infection. The decreased expression of CDK6, not CDK4, induced by matrine was rescued by ectopic expression of c-Myc protein. Conclusions This study has shown for the first time that matrine suppresses cell growth of DLBCL via inhibiting CaMKIIγ/c-Myc/CDK6 signaling pathway.

Abstract Background C-Myc overexpression is associated with poor prognosis and aggressive progression of natural killer/T-cell lymphoma (NKTCL). Matrine, a main alkaloid of the traditional Chinese herb Sophora flavescens Ait, has been shown to inhibit cellular proliferation and induce apoptosis of various cancer cells. The present study investigated the effects and possible mechanisms of matrine inhibiting the growth of natural killer/T-cell lymphoma cells. Methods The effects of matrine on the proliferation, apoptosis and expression of apoptotic molecules, STAT3, LMP1, RUNX3, EZH2 and activation of CaMKIIγ/c-Myc pathway were examined in cultured NKTCL cell line NK92 cells. Results In cultured NK92 cells, matrine inhibited the proliferation in a dose and time dependent manner. The IC50 value of matrine was 1.71 mM for 72 h post exposure in NK92 cells. Matrine induced apoptosis with decreased Bcl-2 expression and the proteasome-dependent degradation of c-Myc protein in NK92 cells. c-Myc protein half-life in NK92 was reduced from 80.7 min to 33.4 min after matrine treatment, which meant the stability of c-Myc was decreased after matrine exposure. Furthermore, we found that matrine downregulated c-Myc phosphorylation at Ser62 together with the inhibition of CaMKIIγ, a key regulator of c-Myc protein in NKTCL. The downregulation of c-Myc transcription by matrine was mediated through LMP1 inhibition. We also observed that anti-proliferative activity of matrine was irrelevant to STAT3, RUNX3 and EZH2. Conclusions The results of the present study indicated that matrine inhibits the growth of natural killer/T-cell lymphoma cells by modulating LMP1-c-Myc and CaMKIIγ-c-Myc signaling pathway.

Transmembrane protease serine 4 (TMPRSS4) is upregulated in various kinds of human cancers, including pancreatic cancer. However, its biological function in pancreatic ductal adenocarcinoma (PDAC) remains unclear. In the current study, real-time qPCR, immunohistochemical staining, Western blotting, and database (Cancer Genome Atlas and Gene Expression) analysis revealed remarkable overexpression of TMPRSS4 in PDAC tissue as compared to non-tumor tissue. The TMPRSS4 overexpression was associated with poor prognosis of PDAC patients. Moreover, multivariate analysis revealed that TMPRSS4 serves as an independent risk factor in PDAC. We performed gain-and loss-of-function analysis and found that TMPRSS4 promotes cellular proliferation and inhibits apoptosis of PDAC cells both in vitro and in vivo. Furthermore, we showed that TMPRSS4 might promote cell proliferation and inhibit apoptosis through activating ERK1/2 signaling pathway in pancreatic cancer cells. These findings were validated by using ERK1/2 phosphorylation inhibitor SCH772984 both in vitro and in vivo. Taken together, this study suggests that TMPRSS4 is a proto-oncogene, which promotes initiation and progression of PDAC by controlling cell proliferation and apoptosis. Our findings indicate that TMPRSS4 could be a promising prognostic biomarker and a therapeutic target for the treatment of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is associated with several genetic syndromes. However, the molecular mechanism underlying PDAC progression is still unknown. In this study, we showed that Laminin Subunit Beta 3 (LAMB3) was aberrantly overexpressed in PDAC and was closely associated with the overall survival rate of patients with PDAC. Functional studies demonstrated that LAMB3 played important roles in cell proliferation, the cell cycle, and invasion capacity. Using bioinformatics analysis, we determined that miR-24-3p was an upstream miRNA of LAMB3, and further experiments verified that miR-24-3p regulated LAMB3 expression in PDAC cells. A dual-luciferase reporter system demonstrated that miR-24-3p directly targeted the LAMB3 3'UTR, and FISH assay confirmed that miR-24-3p and LAMB3 mRNA mostly resided in cytoplasm, accounting for their post-translational regulation. Rescue assay demonstrated that miR-24-3p exerted its anti-cancer role by suppressing LAMB3 expression. Finally, by using a subcutaneous xenotransplanted tumor model, we demonstrated that miR-24-3p overexpression inhibited the proliferation of PDAC by suppressing LAMB3 expression in vivo. Collectively, our results provide evidence that the miR-24-3p/LAMB3 axis plays a vital role in the progression of PDAC and indicate that the miR-24-3p/LAMB3 axis may represent a novel therapeutic target for PDAC.

AbstractContext Levodopa combined with traditional Chinese medicine has a synergistic effect on Parkinson’s disease (PD). Recently, we demonstrated that Nardostachys jatamansi (D. Don) DC. [syn. Patrinia jatamansi D.Don, N. grandiflora DC.] (Valerianaceae) (NJ) can alleviate PD.Objective To explore the synergistic effect of NJ combined with levodopa against PD.Materials and methods The PD model was established by injecting rotenone. Eighty-four Sprague-Dawley rats were randomly divided into seven groups: sham, model, different doses of NJ (0.31, 0.62, or 1.24 g/kg) combined with levodopa (25 mg/kg), and levodopa alone (25 and 50 mg/kg) groups. The synergistic effect of the combination was investigated by pharmacodynamic investigation and detection of expression of nuclear factor erythro2-related factor 2 (Nrf2) and NLR family proteins containing Pyrin-related domain 3 (NLRP3) pathways.Results Compared with the model group, NJ + levodopa (1.24 g/kg + 25 mg/kg) increased the moving distance of PD rats in the open field (2395.34 ± 668.73 vs. 1501.41 ± 870.23, p

BackgroundAlzheimer’s disease (AD) is a multifactorial neurodegenerative condition. The search for multi-target traditional Chinese medicines or ingredients for treating AD has attracted much attention. Corydalis rhizome (CR) is a traditional Chinese medicine. Its main components are alkaloids, which have therapeutic effects that can potentially be used for treating AD. However, no systematic study has been conducted to explore the anti-AD efficacy of CR, as well as its active compounds and mechanisms of action.ObjectiveThe present study aimed to clarify CR’s active constituents and its pharmacological mechanisms in treating AD.MethodsA D-galactose & scopolamine hydrobromide-induced AD mouse model was used and CR was administered orally. The prototypical alkaloid components were identified in the serum. The core components, key targets, and possible mechanisms of action of these alkaloids were revealed through network pharmacology. Molecular docking of the key target was performed. Finally, the mechanism was validated by lipopolysaccharide (LPS)-induced activation of BV2 microglia.ResultsThe results showed that CR improved anxiety-like behavior, spatial and non-spatial recognition, and memory capacity in AD mice. It also achieved synergistic AD treatment by modulating neurotransmitter levels, anti-neuroinflammation, and anti-oxidative stress. The core components that enhance CR’s efficacy in treating AD are protoberberine-type alkaloids. The CR may induce the polarization of LPS-activated BV2 microglia from phenotype M1 to M2. This is partially achieved by modulating the IL-6/JAK2/STAT3 signaling pathway, which could be the mechanism by which CR treats AD through anti-inflammation.ConclusionThe present study provided a theoretical and experimental basis for the clinical application of CR in treating AD. It also provides information that aids the secondary development, and precise clinical use of CR.

The eukaryotic B-family DNA polymerases include four members: Polα, Polδ, Polδ, and Pol ζ, which share common architectural features, such as the exonuclease/polymerase and C-terminal domains (CTDs) of catalytic subunitsboundto indispensable B-subunits, which serve as scaffolds that mediate interactions with other components of the replication machinery. Crystal structures for the B-subunits of Polα and Polδ/Polζ have been reported: the former within the primosome and separately with CTD and the latter with the N-terminal domain of the C-subunit. Here we present the crystal structure of the human Polδ B-subunit (p59) in complex with CTD of the catalytic subunit (p261C). The structure revealed a well defined electron density for p261C and the phosphodiesterase and oligonucleotide/ oligosaccharide-binding domains of p59. However, electron density was missing for the p59 N-terminal domain and for the linker connecting it to the phosphodiesterase domain. Similar to Polα, p261C of Polδ contains a three-helix bundle in the middle and zinc-binding modules on each side. Intersubunit interactions involving 11 hydrogen bonds and numerous hydrophobic contacts account for stable complex formation with a buried surface area of 3094 Å2. Comparative structural analysis of p59-p261C with the corresponding Polα complex revealed significant differences between the B-subunits and CTDs, as well as their interaction interfaces. The B-subunit of Polδ/Polζ also substantially differs from B-subunits of either Polα or Polδ. This work provides a structural basis to explain biochemical and genetic data on the importance of B-subunit integrity in replisome function in vivo. [ABSTRACT FROM AUTHOR]

Excitatory glutamatergic neurotransmission mediated through N-methyl-D-Aspartate (NMDA) receptors (NMDARs) is essential for synaptic plasticity and neuronal survival. While under pathological states, abnormal NMDAR activation is involved in the occurrence and development of psychiatric disorders, which suggests a directional modulation of NMDAR activity that contributes to the remission and treatment of psychiatric disorders. This review thus focuses on the involvement of NMDARs in the pathophysiological processes of psychiatric mood disorders and analyzes the neuroprotective mechanisms of NMDARs. Firstly, we introduce NMDAR-mediated neural signaling pathways in brain function and mood regulation as well as the pathophysiological mechanisms of NMDARs in emotion-related mental disorders such as anxiety and depression. Then, we provide an in-depth summary of current NMDAR modulators that have the potential to be developed into clinical drugs and their pharmacological research achievements in the treatment of anxiety and depression. Based on these findings, drug-targeting for NMDARs might open up novel territory for the development of therapeutic agents for refractory anxiety and depression.

In eukaryotic DNA replication, short RNA-DNA hybrid primers synthesized by primase-DNA polymerase α (Prim-Pol α) are needed to start DNA replication by the replicative DNA polymerases, Pol δ and Pol ϵ. The C terminus of the Pol α catalytic subunit (p180C) in complex with the B subunit (p70) regulates the RNA priming and DNA polymerizing activities of Prim-Pol α. It tethers Pol α and primase, facilitating RNA primer handover from primase to Pol α. To understand these regulatory mechanisms and to reveal the details of human Pol α organization, we determined the crystal structure of p70 in complex with p180C. The structured portion of p70 includes a phosphodiesterase (PDE) domain and an oligonucleotide/oligosaccharide binding (OB) domain. The N-terminal domain and the linker connecting it to the PDE domain are disordered in the reported crystal structure. The p180C adopts an elongated asymmetric saddle shape, with a three-helix bundle in the middle and zinc-binding modules (Zn1 and Zn2) on each side. The extensive p180C-p70 interactions involve 20 hydrogen bonds and a number of hydrophobic interactions resulting in an extended buried surface of 4080 Å2. Importantly, in the structure of the p180C-p70 complex with full-length p70, the residues from the N-terminal to the OB domain contribute to interactions with p180C. The comparative structural analysis revealed both the conserved features and the differences between the human and yeast Pol α complexes. [ABSTRACT FROM AUTHOR]

Anxiety disorder impacts the quality of life of the patients. The 95% ethanol extract of rhizomes and roots of Valeriana jatamansi Jones (Zhi zhu xiang, ZZX) has previously been shown to be effective for the treatment of anxiety disorder. In this study, the dose ratio of each component of the anxiolytic compounds group (ACG) in a 95% ethanol extract of ZZX was optimized by a uniform design experiment and mathematical modeling. The anxiolytic effect of ACG was verified by behavioral experiments and biochemical index measurement. Network pharmacology was used to determine potential action targets, as well as predict biological processes and signaling pathways, which were then verified by molecular docking analysis. Metabolomics was then used to screen and analyze metabolites in the rat hippocampus before and after the administration of ZZX-ACG. Finally, the results of metabolomics and network pharmacology were integrated to clarify the anti-anxiety mechanism of the ACG. The optimal dose ratio of ACG in 95% ethanol extract of ZZX was obtained, and our results suggest that ACG may regulate ALB, AKT1, PTGS2, CYP3A4, ESR1, CASP3, CYP2B6, EGFR, SRC, MMP9, IGF1, and MAPK8, as well as the prolactin signaling pathway, estrogen signaling pathway, and arachidonic acid metabolism pathway, thus affecting the brain neurotransmitters and HPA axis hormone levels to play an anxiolytic role, directly or indirectly.

The therapeutic goals of patients with chronic pain are not only to relieve pain but also to improve the quality of life. Chronic pain negatively affects various aspects of daily life, such as by decreasing the motivation to work and reward sensitivity, which may lead to difficulties in daily life or even unemployment. Human and animal studies have shown that chronic pain damages reward processing; the exploration of associated internal mechanisms may aid the development of treatments to repair this damage. Incentive salience theory, used widely to describe reward processing, divides this processing into “liking” (reward-induced hedonic sensory impact) and “wanting” (reward-induced motivation) components. It has been employed to explain pathological changes in reward processing induced by psychiatric disorders. In this review, we summarize the findings of studies of reward processing under chronic pain and examine the effects of chronic pain on “liking” and “wanting.” Evidence indicates that chronic pain compromises the “wanting” component of reward processing; we also discuss the neural mechanisms that may mediate this effect. We hope that this review aids the development of therapies to improve the quality of life of patients with chronic pain.

Previous studies have reported the failure of cognitive emotion regulation (CER), especially in regulating unpleasant emotions under stress. The underlying reason for this failure was the application of CER depends heavily on the executive function of the prefrontal cortex (PFC), but this function can be impaired by stress-related neuroendocrine hormones. This observation highlights the necessity of developing self-regulatory strategies that require less top-down cognitive control. Based on traditional Chinese philosophy and medicine, which examine how different types of emotions promote or counteract one another, we have developed a novel emotion regulation strategy whereby one emotion is used to alter another. For example, our previous experiment showed that sadness induction (after watching a sad film) could reduce aggressive behavior associated with anger [i.e., “sadness counteracts anger” (SCA)] (Zhan et al., 2015). Relative to the CER strategy requiring someone to think about certain cognitive reappraisals to reinterpret the meaning of an unpleasant situation, watching a film or listening to music and experiencing the emotion contained therein seemingly requires less cognitive effort and control; therefore, this SCA strategy may be an alternative strategy that compensates for the limitations of cognitive regulation strategies, especially in stressful situations. The present study was designed to directly compare the effects of the CER and SCA strategy in regulating anger and anger-related aggression in stressful and non-stressful conditions. Participants’ subjective feeling of anger, anger-related aggressive behavior, skin conductance, and salivary cortisol and alpha-amylase levels were measured. Our findings revealed that acute stress impaired one’s ability to use CR to control angry responses provoked by others, whereas stress did not influence the efficiency of the SCA strategy. Compared with sadness or neutral emotion induction, CER induction was found to reduce the level of subjective anger more, but this difference only existed in non-stressful conditions. By contrast, irrespective of stress, the levels of aggressive behavior and related skin conductance after sadness induction were both significantly lower than those after CER induction or neutral emotion induction, thus suggesting the immunity of the regulatory effect of SCA strategy to the stress factor.

The human primosome, a 340-kilodalton complex of primase and DNA polymeraseα (Polα), synthesizes chimeric RNA-DNA primers to be extended by replicativeDNApolymerases δ and ε. The intricate mechanism of concerted primer synthesis by two catalytic centers was an enigma for over three decades. Here we report the crystal structures of two key complexes, the human primosome and the C-terminal domain of the primase large subunit (p58C) with bound DNA/RNA duplex. These structures, along with analysis of primase/polymerase activities, provide a plausible mechanism for all transactions of the primosome including initiation, elongation, accurate counting of RNA primer length, primer transfer to Polα, and concerted autoregulation of alternate activation/inhibition of the catalytic centers. Our findings reveal a central role of p58C in the coordinated actions of two catalytic domains in the primosome and ultimately could impact the design of anticancer drugs. [ABSTRACT FROM AUTHOR]

DNAreplication in almost all organisms depends on the activity of DNA primase, a DNA-dependent RNA polymerase that synthesizes shortRNAprimers of defined size forDNApolymerases. Eukaryotic and archaeal primases are heterodimers consisting of small catalytic and large accessory subunits, both of which are necessary for the activity. The mode of interaction of primase subunits with substrates during the various steps of primer synthesis that results in the counting of primer length is not clear. Here we show that the C-terminal domain of the large subunit (p58C) plays a major role in template-primer binding and also defines the elements of theDNAtemplate and theRNA primer that interact with p58C. The specific mode of interaction with a template-primer involving the terminal 5'-triphosphate of RNA and the 3'-overhang of DNA results in a stable complex between p58C and the DNA/RNA duplex. Our results explain how p58C participates in RNA synthesis and primer length counting and also indicate that the binding site for initiating NTP is located on p58C. These findings provide notable insight into the mechanism of primase function and are applicable for DNA primases from other species. [ABSTRACT FROM AUTHOR]

DNA replication in bacteria and eukaryotes requires the activity of DNA primase, a DNA-dependent RNA polymerase that lays short RNA primers for DNA polymerases. Eukaryotic and archaeal primases are heterodimers consisting of small catalytic and large accessory subunits, both of which are necessary for RNA primer synthesis. Understanding of RNA synthesis priming in eukaryotes is currently limited due to the lack of crystal structures of the full-length primase and its complexes with substrates in initiation and elongation states. Here we report the crystal structure of the full-length human primase, revealing the precise overall organization of the enzyme, the relative positions of its functional domains, and the mode of its interaction with modeled DNA and RNA. The structure indicates that the dramatic conformational changes in primase are necessary to accomplish the initiation and then elongation of RNA synthesis. The presence of a long linker between the N- and C-terminal domains of p58 provides the structural basis for the bulk of enzyme's conformational flexibility. Deletion of most of this linker affected the initiation and elongation steps of the primer synthesis. [ABSTRACT FROM AUTHOR]