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RNase H2 consists of three subunits (H2A, H2B and H2C) and is involved in the hydrolysis of RNA/DNA hybrids. The GRG motif in RNase H2 is highly conserved and recognizes the ribonucleotides misincorporated into dsDNA. The mutant G37S in the GRG motif of human RNase H2A was found to be correlated with Aicardi-Goutièressyndrome (AGS). In this study, 4 mutants (G37S, G37A, R38A and G39A) were prepared and their biochemical properties of secondary structure, activity and binding affinity with substrate were studied in order to explore the function of the GRG motif. The activity assay showed that the mutations resulted in significantly decreased RNase activity. The binding efficiency assay demonstrated that binding affinities between 4 mutants and 1-ribo FAMlabeled substrate were significantly weakened. These results all indicated that the GRG motif contributes directly to substrate binding and is closely related to the enzyme activity.

Abstract Background Src plays various roles in tumour progression, invasion, metastasis, angiogenesis and survival. It is one of the multiple targets of multi-target kinase inhibitors in clinical uses and trials for the treatment of leukemia and other cancers. These successes and appearances of drug resistance in some patients have raised significant interest and efforts in discovering new Src inhibitors. Various in-silico methods have been used in some of these efforts. It is desirable to explore additional in-silico methods, particularly those capable of searching large compound libraries at high yields and reduced false-hit rates. Results We evaluated support vector machines (SVM) as virtual screening tools for searching Src inhibitors from large compound libraries. SVM trained and tested by 1,703 inhibitors and 63,318 putative non-inhibitors correctly identified 93.53%~ 95.01% inhibitors and 99.81%~ 99.90% non-inhibitors in 5-fold cross validation studies. SVM trained by 1,703 inhibitors reported before 2011 and 63,318 putative non-inhibitors correctly identified 70.45% of the 44 inhibitors reported since 2011, and predicted as inhibitors 44,843 (0.33%) of 13.56M PubChem, 1,496 (0.89%) of 168 K MDDR, and 719 (7.73%) of 9,305 MDDR compounds similar to the known inhibitors. Conclusions SVM showed comparable yield and reduced false hit rates in searching large compound libraries compared to the similarity-based and other machine-learning VS methods developed from the same set of training compounds and molecular descriptors. We tested three virtual hits of the same novel scaffold from in-house chemical libraries not reported as Src inhibitor, one of which showed moderate activity. SVM may be potentially explored for searching Src inhibitors from large compound libraries at low false-hit rates.

Abstract Background Zbtb7A is a proto-oncogenic transcriptional regulator that plays an important role in adipogenesis, osteogenesis and oncogenesis, but little is known about the regulation of Zbtb7A gene expression which is of importance in the function uncovering of this gene. Finding Here, a 5'-flanking region of the human Zbtb7A gene was cloned and characterized. It was found that the GC box within Zbtb7A promoter is necessary for the promoter activity. Furthermore, we identified that Sp1 acts as an activator in the regulation of Zbtb7A promoter activity and the physical interaction between Sp1 and GC box is responsible for the activation of Zbtb7A gene promoter. Conclusion Our results confirmed that Sp1 upregulates Zbtb7A gene expression via direct binding to GC box within the promoter.

Triple‐negative breast cancer (TNBC), a disease with a poor prognosis and high mortality, is difficult to targeted therapy, due to the metastatic nature of TNBC cells and their lack of estrogen, progesterone, and Her‐2/Neu receptor targets. Here, a novel pretargeting strategy involving self‐assembled peptides and a bioorthogonal reaction are described. This process generates nanofibers on TNBC cell surface that prevent them migration and invasion and deliver untargeted anticancer drugs (e.g., doxorubicin) that synergistically eliminates TNBC cells. The self‐assembled peptide contains four modules: i) an aromatic group‐rich tetraphenylethylene (TPE) unit for promoting self‐assembly and nanofiber formation, ii) a GFFY peptide motif that supports self‐assembly of nanofibers into peptide scaffolds, iii) a targeting RGD motif that binding with the abundant integrin molecules present on TNBC cell surface, and iv) an azide group acting as the bioorthogonal reaction site that reacts with drugs or probes containing the dibenzocyclooctyne (DBCO) group. Results of in vitro and in vivo experiments indicate that the self‐assembled peptide inhibits tumor invasion and metastasis, while also pretargeting and killing TNBC cells with superior effectiveness and lower toxicity to that of current chemotherapies. In conclusion, this novel bioorthogonal pretargeting strategy holds promise as an effective anticancer therapeutic approach. [ABSTRACT FROM AUTHOR]

Proteolysis‐targeting chimeras (PROTACs) are essential bifunctional molecules that target proteins of interest (POIs) for degradation by cellular ubiquitination machinery. Despite significant progress made in understanding PROTACs' functions, their therapeutic potential remains largely untapped. As a result of the success of highly flexible, scalable, and low‐cost mRNA therapies, as well as the advantages of the first generation of peptide PROTACs (p‐PROTACs), we present for the first time an engineering mRNA PROTACs (m‐PROTACs) strategy. This design combines von Hippel–Lindau (VHL) recruiting peptide encoding mRNA and POI‐binding peptide encoding mRNA to form m‐PROTAC and promote cellular POI degradation. We then performed proof‐of‐concept experiments using two m‐PROTACs targeting two cancer‐related proteins, estrogen receptor alpha and B‐cell lymphoma‐extra large protein. Our results demonstrated that m‐PROTACs could successfully degrade the POIs in different cell lines and more effectively inhibit cell proliferation than the traditional p‐PROTACs. Moreover, the in vivo experiment demonstrated that m‐PROTAC led to significant tumor regression in the 4T1 mouse xenograft model. This finding highlights the enormous potential of m‐PROTAC as a promising approach for targeted protein degradation therapy. [ABSTRACT FROM AUTHOR]