Design and synthesis of unprecedented 9- and 10-membered cyclonucleosides with PRMT5 inhibitory activity

Synthesis and applications of cyclonucleosides: an update (2010-2023)

Cyclonucleosides are a group of nucleoside derivatives which, in addition to the classical N-glycosidic bond, have an additional covalent bond (linker, bridge) in their structure, which connects the heterocyclic base and sugar ring. The majority of them have been discovered in the laboratory; however, few such compounds have also been found in natural sources, including metabolites of sponges or radical damage occurring in nucleic acids. Due to their structural properties-rigid, fixed conformation-they have found wide applications in medicinal chemistry and biochemistry as biocides as well as enzyme inhibitors and molecular probes. They have also found use as convenient synthetic tools for the preparation of new nucleoside analogues, enabling structural modifications of both the sugar ring and heterocyclic base. This review summarizes the recent progress in the synthesis of various purine and pyrimidine cyclonucleosides using diverse chemical approaches based on radical, "click", metal-mediated, and other types of reactions. It also presents recent reports concerning possible applications in medicinal chemistry, as well as their applications as valuable key intermediates in the synthesis of sugar- and base-modified nucleoside analogues and heterocyclic compounds.

Targeting Arginine Methyltransferase PRMT5 for Cancer Therapy: Updated Progress and Novel Strategies

As a predominant type II protein arginine methyltransferase, PRMT5 plays critical roles in various normal cellular processes by catalyzing the mono- and symmetrical dimethylation of a wide range of histone and nonhistone substrates. Clinical studies have revealed that high expression of PRMT5 is observed in different solid tumors and hematological malignancies and is closely associated with cancer initiation and progression. Accordingly, PRMT5 is becoming a promising anticancer target and has received great attention in both the pharmaceutical industry and the academic community. In this Perspective, we comprehensively summarize recent advances in the development of first-generation PRMT5 enzymatic inhibitors and highlight novel strategies targeting PRMT5 in the past 5 years. We also discuss the challenges and opportunities of PRMT5 inhibition, with the aim of shedding light on future PRMT5 drug discovery.

The Structural Effects of Phosphorylation of Protein Arginine Methyltransferase 5 on Its Binding to Histone H4

The protein arginine methyltransferase 5 (PRMT5) enzyme is responsible for arginine methylation on various proteins, including histone H4. PRMT5 is a promising drug target, playing a role in the pathomechanism of several diseases, especially in the progression of certain types of cancer. It was recently proved that the phosphorylation of PRMT5 on T80 residue increases its methyltransferase activity; furthermore, elevated levels of the enzyme were measured in the case of human hepatocellular carcinoma and other types of tumours. In this study, we constructed the complexes of the unmodified human PRMT5-methylosome protein 50 (MEP50) structure and its T80-phosphorylated variant in complex with the full-length histone H4 peptide. The full-length histone H4 was built in situ into the human PRMT5-MEP50 enzyme using experimental H4 fragments. Extensive molecular dynamic simulations and structure and energy analyses were performed for the complexed and apo protein partners, as well. Our results provided an atomic level explanation for two important experimental findings: (1) the increased methyltransferase activity of the phosphorylated PRMT5 when compared to the unmodified type; (2) the PRMT5 methylates only the free form of histone H4 not bound in the nucleosome. The atomic level complex structure H4-PRMT5-MEP50 will help the design of new inhibitors and in uncovering further structure–function relationships of PRMT enzymes.