verticillins and chaetocin

Verticillin is one of the dimeric epipolythiodioxopiperazines (ETPs) which are toxic secondary metabolites produced only by fungi. ETPs have received substantial attention since its complex molecular architecture and a wide range of biological activities. Although biosynthesis of the monomeric gliotoxin has been studied extensively, the biosynthetic pathway of dimeric ETPs is far from being studied. To investigate the biosynthesis of dimeric ETPs and expand our understanding of their dimerization, the verticillin biosynthetic gene cluster (ver) was identified and cloned from a genomic DNA fosmid library of the Cordyceps-colonizing fungus Clonostachys rogersoniana with the designed primers based on the sequence of a nonribosomal peptide synthetase (NRPS) ChaP which was predicted to be responsible for chaetocin biosynthesis in Chaetomium virescens. To validate it, the chaP homologous gene verP in the ver cluster was disrupted. HPLC-MS analysis demonstrated that the verP disruption mutant (ΔverP) completely abolished verticillin production, and it could be restored by introducing a copy of the wild-type verP gene. Further gene disruptions and chemical analysis demonstrated that most genes of this ver cluster were essential for verticillin biosynthesis. Intriguingly, disruption of verP almost abolished the conidiation of Clonostachys rogersoniana and it was partially restored by addition of the fermentation extract which contains verticillin, implying that verticillin or its intermediate plays a role in the Cordyceps-colonizing fungal morphological differentiation.

Topics: Biosynthetic Pathways; Hypocreales; Indoles; Multigene Family; Peptide Synthases; Piperazines

Pancreatic cancer is one of the cancers where anti-PD-L1/PD-1 immunotherapy has been unsuccessful. What confers pancreatic cancer resistance to checkpoint immunotherapy is unknown. The aim of this study is to elucidate the underlying mechanism of PD-L1 expression regulation in the context of pancreatic cancer immune evasion.. Pancreatic cancer mouse models and human specimens were used to determine PD-L1 and PD-1 expression and cancer immune evasion. Histone methyltransferase inhibitors, RNAi, and overexpression were used to elucidate the underlying molecular mechanism of PD-L1 expression regulation. All statistical tests were two-sided.. PD-L1 is expressed in 60% to 90% of tumor cells in human pancreatic carcinomas and in nine of 10 human pancreatic cancer cell lines. PD-1 is expressed in 51.2% to 52.1% of pancreatic tumor-infiltrating cytotoxic T lymphocytes (CTLs). Tumors grow statistically significantly faster in FasL-deficient mice than in wild-type mice (P = .03-.001) and when CTLs are neutralized (P = .03-<.001). H3K4 trimethylation (H3K4me3) is enriched in the cd274 promoter in pancreatic tumor cells. MLL1 directly binds to the cd274 promoter to catalyze H3K4me3 to activate PD-L1 transcription in tumor cells. Inhibition or silencing of MLL1 decreases the H3K4me3 level in the cd274 promoter and PD-L1 expression in tumor cells. Accordingly, inhibition of MLL1 in combination with anti-PD-L1 or anti-PD-1 antibody immunotherapy effectively suppresses pancreatic tumor growth in a FasL- and CTL-dependent manner.. The Fas-FasL/CTLs and the MLL1-H3K4me3-PD-L1 axis play contrasting roles in pancreatic cancer immune surveillance and evasion. Targeting the MLL1-H3K4me3 axis is an effective approach to enhance the efficacy of checkpoint immunotherapy against pancreatic cancer.

Topics: Animals; Antibodies, Monoclonal; B7-H1 Antigen; Carcinoma; Cell Line, Tumor; DNA Methylation; Down-Regulation; Epigenesis, Genetic; Fas Ligand Protein; Female; Histone-Lysine N-Methyltransferase; Humans; Immunotherapy; Indoles; Mice; Mice, Inbred C57BL; Myeloid-Lymphoid Leukemia Protein; Neoplasm Transplantation; Pancreatic Neoplasms; Piperazines; Programmed Cell Death 1 Receptor; Promoter Regions, Genetic; RNA, Messenger; T-Lymphocytes, Cytotoxic; Tumor Escape; Tumor Microenvironment

Topics: Azepines; Crystallization; Disulfides; Drug Design; Enzyme Inhibitors; Gliotoxin; Histone Methyltransferases; Histone-Lysine N-Methyltransferase; Indole Alkaloids; Methylation; Piperazines; Quinazolines