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Growing evidence suggests that certain cell cycle regulators also mediate neuronal death. Of relevance, cyclin D1-associated kinase activity is increased and the retinoblastoma protein (Rb), a substrate of the cyclin D1-Cdk4/6 complex, is phosphorylated during K ؉ deprivation-evoked death of cerebellar granule neurons (CGNs). Cyclin-dependent kinase (CDK) inhibitors block this death, suggesting a requirement for the cyclin D1/ Cdk4/6-Rb pathway. However, the downstream target(s) of this pathway are not well defined. The transcription factor E2F-1 is regulated by Rb and is reported to evoke death in proliferating cells when overexpressed. Accordingly, we examined whether E2F-1 was sufficient to evoke death of CGNs and whether it was required for death evoked by low K ؉ . We show that adenovirus-mediated expression of E2F-1 in CGNs results in apoptotic death, which is independent of p53, dependent upon Bax, and associated with caspase 3-like activity. In addition, we demonstrate that levels of E2F-1 mRNA and protein increase during K ؉ deprivation-evoked death. The increase in E2F-1 protein is blocked by the CDK inhibitor flavopiridol. Finally, E2F-1-deficient neurons are modestly resistant to death induced by low K ؉ . These results indicate that E2F-1 expression is sufficient to promote neuronal apoptosis and that endogenous E2F-1 modulates the death of CGNs evoked by low K ؉ .

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Two homologous meroterpenoid gene clusters consisting of contiguous genes encoding polyketide synthase (PKS), prenyltransferase (PT), terpenoid cyclase (TC) and other tailoring enzymes were identified from two phylogenetically distinct fungi through computational analysis. Media optimization guided by reverse-transcription PCR (RT-PCR) enabled two strains to produce eight new and two known meroterpenoids (1-10). Using gene inactivation, heterologous expression, and biochemical analyses, we revealed a new polyketide-terpenoid assembly line that utilizes a pair of PKSs to synthesize 2,4-dihydroxy-6-alkylbenzoic acid, followed by oxidative decarboxylation, farnesyl transfer, and terpene cyclization to construct the meroterpenoid scaffold. In addition, two of the isolated meroterpenoids (3 and 17 d) showed immunosuppressive bioactivity. Our work reveals a new strategy for meroterpenoid natural products discovery, and reveals the biosynthetic pathway for compounds 1-10.

Xiyanping (XYP) is a Chinese herbal medicine used in the clinic to treat respiratory infection and pneumonia. Recent evidence identified XYP as a potential inhibitor of severe acute respiratory syndrome coronavirus 2, implying XYP as a possible treatment for the coronavirus disease 2019 (COVID‐19). Here, we conducted a prospective, multicenter, open‐label and randomized controlled trial to evaluate the safety and effectiveness of XYP injection in patients with mild to moderate COVID‐19. We consecutively recruited 130 COVID‐19 patients with mild to moderate symptoms from five study sites, and randomized them in 1:1 ratio to receive XYP injection in combination with standard therapy or receive standard supportive therapy alone. We found that XYP injection significantly reduced the time to cough relief, fever resolution and virus clearance. Less patients receiving XYP injection experienced disease progression to the severe stage during the treatment process. No severe adverse events were reported during the study. Taken together, XYP injection is safe and effective in improving the recovery of patients with mild to moderate COVID‐19. However, further studies are warranted to evaluate the efficacy of XYP in an expanded cohort comprising COVID‐19 patients at different disease stages.