ABSTRACT
The E2F family of transcription factors is crucial for cell cycle progression and cell fate decisions. Although E2Fs have been widely studied in mammals, there have been few studies performed in insects. Here, we determined the function of E2F4 in the silkworm, Bombyx mori. We demonstrate that E2F proteins are highly conserved among species from lower animals to higher mammals. Overexpression of the BmE2F4 gene led to cell cycle arrest in the G1 phase, whereas interfering with the BmE2F4 mRNA led to accumulation of cells in the S phase. These results indicate that BmE2F4 is important in cell cycle regulation. We also demonstrate that the BmE2F4 gene is involved in DNA replication of BmN-SWU1 cells and DNA synthesis in the silk gland. Furthermore, we identified a protein called Bm14-3-3ζ that can interact with BmE2F4 and allow it to localize in the nucleus. Overexpression of the Bm14-3-3ζ gene led to cell cycle arrest in the G1 phase, while knocking down the gene increased the proportion of cells in S phase. These findings provide important insights into the function of E2F transcription factors and increase our understanding of their involvement in cell cycle regulation.
Subject(s)
Bombyx , Animals , Bombyx/metabolism , Cell Cycle , DNA Replication , Insect Proteins/genetics , Insect Proteins/metabolism , Mammals/metabolism , Transcription Factors/geneticsABSTRACT
BACKGROUND: Caesalpinia sappan L. is a traditional medicinal plant that is used to promote blood circulation and treat stroke in China. Protosappanin B (PTB) is a unique homoisoflavone compound isolated from Sappan Lignum (the heartwood of Caesalpinia sappan L). In a previous study, the metabolic fate of PTB remained unknown. OBJECTIVE: To explore whether PTB is extensively metabolized, the metabolites of PTB in bile, plasma, urine, feces, and intestinal bacteria samples in rats were investigated. METHODS: The biosamples were investigated by ultraperformance liquid chromatography combined with time-offlight mass spectrometry (UPLC-TOF-MS/MS) with MetabolitePilot software. RESULTS: 28 metabolites were identified in the biosamples: 18 metabolites in rat bile, 8 in plasma, 20 in feces, 7 in urine and 2 in intestinal bacteria samples. Both phase I and phase II metabolites were observed. Metabolite conversion occurred via 9 proposed pathways: sulfate conjugation, glucuronide conjugation, bis-glucuronide conjugation, glucose conjugation, dehydration, oxidation, hydrolysis, methylation and hydroxymethylene loss. The metabolic pathways differed among biosamples and exhibited different distributions. Among these pathways, the most important was sulfate and glucuronide conjugation. CONCLUSION: The results showed that the small intestinal and biliary routes play an important role in the clearance and excretion of PTB. The main sites of metabolism in the PTB chemical structure were the phenolic hydroxyl and the side-chains on the eight-element ring.
Subject(s)
Bile/metabolism , Feces/chemistry , Gastrointestinal Microbiome , Oxocins/blood , Oxocins/urine , Animals , Caesalpinia , Chromatography, High Pressure Liquid , Chromatography, Liquid , Male , Oxocins/chemistry , Oxocins/metabolism , Rats , Rats, Sprague-DawleyABSTRACT
Four new sesquiterpenoids, phellinignins A-D (1-4), together with four known ones (5-8), were isolated from cultures of the fungus Phellinus igniarius. The structures were established by extensive spectroscopic methods including MS, NMR, and the single crystal X-ray diffraction. Compounds 1-3 and 5-8 are tremulane sesquiterpenoids, while compound 4 possesses a new carbon skeleton that might derive from an illudane framework. Compounds 1, 2, 4, and 5 showed certain cytotoxicities to three human cancer cell lines.
