Processive DNA synthesis by the aeh core of the Escherichia coli Pol III replicase requires it to be bound to the b 2 clamp via a site in the a polymerase subunit. How the e proofreading exonuclease subunit influences DNA synthesis by a was not previously understood. In this work, bulk assays of DNA replication were used to uncover a non-proofreading activity of e. Combination of mutagenesis with biophysical studies and single-molecule leading-strand replication assays traced this activity to a novel b-binding site in e that, in conjunction with the site in a, maintains a closed state of the aeh-b 2 replicase in the polymerization mode of DNA synthesis. The e-b interaction, selected during evolution to be weak and thus suited for transient disruption to enable access of alternate polymerases and other clamp binding proteins, therefore makes an important contribution to the network of protein-protein interactions that finely tune stability of the replicase on the DNA template in its various conformational states.

Emerging studies indicate that long noncoding RNAs (lncRNAs) play crucial roles in ovarian cancer (OC). By analyzing high-throughput data, we found that SNHG17 was highly expressed in multiple OC cohorts. However, its functions in OC were not explored. In this study, lncRNA expression in OC was analyzed by a series of microarray data. The functions of SNHG17 were investigated by various in vitro and in vivo assays. Fluorescence in situ hybridization (FISH), RNA pull-down, chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), and luciferase reporter assays were used to reveal the potential mechanisms involved in the effects of SNHG17. We found that SNHG17 was overexpressed in OC and that the oncogenic transcription factor STAT3 was involved in promoting its expression. In addition, high SNHG17 expression was associated with a poor prognosis in OC. Functional analysis revealed that SNHG17 could promote OC cell growth. Mechanistically, SNHG17 was found to be located predominantly in the cytoplasm. It could regulate expression of CDK6, an important cell-cycle regulator, by acting as a molecular sponge for miR-214-3p. In summary, our study suggested that SNHG17 acted as an oncogene in OC, which might serve as a novel target for OC diagnosis and therapy.

Background Human dental pulp stromal cells (hDPSCs) are promising sources of mesenchymal stem cells (MSCs) for bone tissue regeneration. Circular RNAs (circRNAs) have been demonstrated to play critical roles in stem cell osteogenic differentiation. Herein, we aimed to investigate the role of circAKT3 during osteogenesis of hDPSCs and the underlying mechanisms of its function. Methods We performed circRNA sequencing to investigate the expression profiles of circular RNAs during osteogenesis of hDPSCs. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to detect the expression pattern of circAKT3 and miR-206 in hDPSCs during osteogenesis. We knocked down circAKT3 and interfered the expression of miR-206 to verify their regulatory role in hDPSC osteogenesis. We detected hDPSCs mineralization by alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining and used dual-luciferase reporter assay to validate the direct binding between circAKT3 and miR-206. To investigate in vivo mineralization, we performed subcutaneous transplantation in nude mice and used hematoxylin and eosin, Masson’s trichrome, and immunohistochemistry staining. Results Totally, 86 circRNAs were differentially expressed during hDPSC osteogenesis, in which 29 were downregulated while 57 were upregulated. circAKT3 was upregulated while miR-206 was downregulated during hDPSC osteogenesis. Knockdown of circAKT3 inhibited ALP/ARS staining and expression levels of osteogenic genes. circAKT3 directly interacted with miR-206, and the latter one suppressed osteogenesis of hDPSCs. Silencing miR-206 partially reversed the inhibitory effect of circAKT3 knockdown on osteogenesis. Connexin 43 (CX43), which positively regulates osteogenesis of stem cells, was predicted as a target of miR-206, and overexpression or knockdown of miR-206 could correspondingly decrease and increase the expression of CX43. In vivo study showed knockdown of circAKT3 suppressed the formation of mineralized nodules and expression of osteogenic proteins. Conclusion During osteogenesis of hDPSCs, circAKT3 could function as a positive regulator by directly sponging miR-206 and arresting the inhibitive effect of miR-206 on CX43 expression.

Numerous studies have indicated that lncRNA PVT1 will most likely become a novel target for cancer therapy with the deepening systematic research.

MicroRNAs(miRNAs) are non-coding single-stranded RNA molecules encoded by endogenous genes with a length of about 22 nucleotides. The dysregulation of miRNAs has been proven to be one of the vital causes of cancer, which makes them a biomarker for cancer diagnosis and prognosis. Compared with surgery and chemotherapy, nucleic acid therapy targeting specific miRNAs is a promising candidate for cancer treatment. miR-20a-5p plays an anticancer role in high-incidence human cancers such as cervical cancer, breast cancer and leukemia, which is of great importance in the diagnosis of cancers. The up-regulation and down-regulation of miR-20a-5p offers a possible breakthrough for the treatment of cancers. In this paper, we aim to investigate the functional significance of miR-20a-5p in different cancers, reviewing the expression differences of miR-20a-5p in cancer, while systematically summarizing the changes of circRNA-miR-20a-5p networks, and probe how it promotes messenger RNA (mRNA) degradation or inhibits mRNA translation to regulate downstream gene expression. We’ve also summarized the biogenesis mechanism of miRNAs, and emphasized its role in cell proliferation, cell apoptosis and cell migration. On this basis, we believe that miR-20a-5p is a promising and effective marker for cancer diagnosis, prognosis and treatment.