Hyposterolactone A, a 3α-Hydroxy Steroidal Lactone from the Deep-Sea-Derived Fungus Hypocrea sp. ZEN14.

Chemical investigation of the deep-sea-derived fungus Hypocrea sp. ZEN14 afforded a new 3α-hydroxy steroidal lactone, hyposterolactone A (1) and 25 known secondary metabolites (2-26). The structure of the new compound was established by detailed spectroscopic analysis, electronic circular dichroism (ECD) calculation as well as a J-based configuration analysis. Compound 10 showed potent cytotoxicity against Huh7 and Jurkat cells with IC50 values of 1.4 µM and 6.7 µM, respectively.

Ferroptosis Inhibitory Compounds from the Deep-Sea-Derived Fungus Penicillium sp. MCCC 3A00126.

Two new xanthones (1 and 2) were isolated from the deep-sea-derived fungus Penicillium sp. MCCC 3A00126 along with 34 known compounds (3-36). The structures of the new compounds were established by spectroscopic data. The absolute configuration of 1 was validated by comparison of experimental and calculated ECD spectra. All isolated compounds were evaluated for cytotoxicity and ferroptosis inhibitory activities. Compounds 14 and 15 exerted potent cytotoxicity against CCRF-CEM cells, with IC50 values of 5.5 and 3.5 µM, respectively, whereas 26, 28, 33, and 34 significantly inhibited RSL3-induced ferroptosis, with EC50 values of 11.6, 7.2, 11.8, and 2.2 µM, respectively.

Brefeldin A from the Deep-Sea-Derived Fungus Fusarium sp. Targets on RIPK3 to Inhibit TNFα-Induced Necroptosis.

From the deep-sea-derived Fusarium sp. ZEN-48, four known compounds were obtained. Their structures were established by extensive analyses of the NMR, HR-ESI-MS, and the X-ray crystallographic data as brefeldin A (BFA, 1), brevianamide F (2), N-acetyltryptamine (3), and (+)-diaporthin (4). Although BFA was extensively investigated for its potent bioactivities, its role on TNFα-induced necroptosis was incompletely understood. In this study, BFA showed significant inhibition on TNFα-induced necroptosis by disrupting the necrosome formation and suppressing the phosphorylation of RIPK3 and MLKL (IC50 =0.5 µM). While, it had no effect on TNFα-induced NF-κB/MAPKs activation and apoptosis. The finding raised significant implications of BFA for necroptosis-related inflammatory disease therapy and new drug development from marine fungi.

GSDME-mediated pyroptosis promotes inflammation and fibrosis in obstructive nephropathy.

Renal tubular cell (RTC) death and inflammation contribute to the progression of obstructive nephropathy, but its underlying mechanisms have not been fully elucidated. Here, we showed that Gasdermin E (GSDME) expression level and GSDME-N domain generation determined the RTC fate response to TNFα under the condition of oxygen-glucose-serum deprivation. Deletion of Caspase-3 (Casp3) or Gsdme alleviated renal tubule damage and inflammation and finally prevented the development of hydronephrosis and kidney fibrosis after ureteral obstruction. Using bone marrow transplantation and cell type-specific Casp3 knockout mice, we demonstrated that Casp3/GSDME-mediated pyroptosis in renal parenchymal cells, but not in hematopoietic cells, played predominant roles in this process. We further showed that HMGB1 released from pyroptotic RTCs amplified inflammatory responses, which critically contributed to renal fibrogenesis. Specific deletion of Hmgb1 in RTCs alleviated caspase11 and IL-1ß activation in macrophages. Collectively, our results uncovered that TNFα/Casp3/GSDME-mediated pyroptosis is responsible for the initiation of ureteral obstruction-induced renal tubule injury, which subsequentially contributes to the late-stage progression of hydronephrosis, inflammation, and fibrosis. This novel mechanism will provide valuable therapeutic insights for the treatment of obstructive nephropathy.

Cisplatin-induced necroptosis in TNFα dependent and independent pathways.

Cisplatin is a chemotherapeutic drug for treatment of many solid tumors. It has been shown to induce apoptosis and/or necrosis in different types of cancer cells. However, the underlying mechanisms remain elusive. In this study, we provide evidences that cisplatin induces necroptosis in receptor-interacting protein 3 (RIP3)-expressing cell lines, but not in cell lines lacking RIP3 protein expression. Deficiency of core components of necroptotic pathway, RIP1, RIP3, or mixed lineage kinase domain-like protein (MLKL) blocked cisplatin-induced cell death in L929 cells. This phenomenon is dependent on RIP1/RIP3/MLKL necrosome formation and translocation to mitochondria-associated membrane (MAM), but only partially via autocrine production of tumor necrosis factor α (TNFα). Moreover, we demonstrate that the mitochondrial permeability transition pore opening (mPTP) opening and reactive oxygen species (ROS) generation is a critical downstream event of the formation of necrosome in cisplatin-induced necroptosis, which is TNFα independent. Deficiency of cyclophilin-D (CypD) partially reduced cisplatin-induced cell death, indicating CypD mediated-mPTP opening plays an important role during cisplatin-induced necroptosis. Both deletion of CypD and TNFα completely blocked cisplatin-induced cell death, suggesting that cisplatin could induce necroptosis through TNFα dependent and independent pathway. These findings provide new insight into the molecular mechanisms underlying cisplatin-induced necroptosis.