Topoisomerase IV inhibitors(Dainippon Pharmaceutical)

A topoisomerase‐DNA transient covalent complex can be a druggable target for novel topoisomerase poison inhibitors that represent a new class of antibacterial or anticancer drugs. Herein, we have investigated molecular features of the functionally important Escherichia coli topoisomerase I (EctopoI)‐DNA covalent complex (EctopoIcc) for molecular simulations, which is very useful in the development of new antibacterial drugs. To demonstrate the usefulness of our approach, we used a model small molecule (SM), NSC76027, obtained from virtual screening. We examined the direct binding of NSC76027 to EctopoI as well as inhibition of EctopoI relaxation activity of this SM via experimental techniques. We then performed molecular dynamics (MD) simulations to investigate the dynamics and stability of EctopoIcc and EctopoI‐NSC76027‐DNA ternary complex. Our simulation results show that NSC76027 forms a stable ternary complex with EctopoIcc. EctopoI investigated here also serves as a model system for investigating a complex of topoisomerase and DNA in which DNA is covalently attached to the protein.

15-Hydroxyeicosatetraenoic acid (15-HETE) is produced by the catalytic metabolism of arachidonic acid by the enzyme 15-lipoxygenase. It is produced during hypoxia, and participates in the remodeling of pulmonary artery smooth muscle (PASM). Previous research has revealed that sirtuin 1 (SIRT1) involved in apoptosis in various cells and tissues. Herein, we attempted to determine whether 15-HETE counteracts SIRT1-promoted cell death in murine PASM cells (PASMCs). To verify this theory, we investigated changes in SIRT1 concentration in response to the counteraction of cell death by 15-HETE. We used western blotting and a terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay, and investigated the survival, nuclear morphology, and mitochondrial potential of the cells. Our results revealed that 15-HETE promotes the transcription and translation of SIRT1. Moreover, 15-HETE increases viability and impaired mitochondrial depolarization, and promotes the expression of Bcl-2 and Bcl-xL in PASMCs without serum. The reactions mentioned above were eliminated by SIRT1 inhibitors (EX 527 and SIRT1 inhibitor IV). Our findings suggest that 15-HETE is crucial for the protection of PASMCs against cell death, and the SIRT1 pathway may provide a new strategy for pulmonary artery hypertension therapy.