Negative Feedback Loop Mechanism between EAF1/2 and DBC1 in Regulating ELL Stability and Functions.

Although ELL-associated factors 1 and 2 (EAF1/2) have been shown to enhance RNA polymerase II-mediated transcription in vitro, their functional roles in vivo are poorly known. In this report, we show functions of these proteins in regulating ELL stability through their competitive binding with HDAC3 at the N terminus of ELL. Reduced HDAC3 binding to ELL causes increased acetylation leading to reduced ubiquitylation-mediated degradation. Similar functional roles played by DBC1 in regulating ELL stability further prompted in-depth analyses that demonstrated presence of negative feedback loop mechanisms between DBC1 and EAF1/2 in maintaining overall ELL level. Mechanistically, increased DBC1 reduces EAF1/2 level through increased ubiquitylation involving E3 ubiquitin ligase TRIM28, whereas increased EAF1/2 reduces DBC1 level through reduced transcription. Physiologically, after a few passages, ELL levels in either DBC1 or EAF1 knockdown cells are restored through enhanced expression of EAF1 and DBC1, respectively. Interestingly, for maintenance of ELL level, mammalian cells prefer the EAF1-dependent pathway during exposure to genotoxic stress, and the DBC1-dependent pathway during exposure to growth factors. Thus, we describe coordinated functions of multiple factors, including EAF1/2, HDAC3, DBC1, and TRIM28 in regulating ELL protein level for optimal target gene expression in a context-dependent manner within mammalian cells.

Anticariogenic activity and phytochemical studies of crude extract from some Indian plant leaves.

AIM: The aim was to screen the selected Indian plants for their antibacterial efficacy against four cariogenic bacteria Lactobacillus acidophilus (LA)(Microbial Type Culture Collection [MTCC]-*447), Lactobacillus casei (LC) (MTCC-1423), Streptococcus mutans (SMU) (MTCC-890) and Staphylococcus aureus (MTCC-96). To identify and characterize active principle present in these plants for the treatment of dental caries. MATERIALS AND METHODS: The dried plant leaves materials are extracted by cold extraction using hexane, ethyl acetate, methanol, and distilled water. The solvents were evaporated, and the dried masses were suspended in dimethyl sulfoxide and used for anticariogenic activity by agar well diffusion method. Minimum inhibitory concentration (MIC) was evaluated by two-fold serial broth dilution method. Preliminary phytochemical analysis of effective extract was carried out by thin-layer chromatography (TLC) and bioautography. RESULTS: Ethyl acetate and hexane extract of Eucalyptus globules was found most effective against L. acidophilus with MIC value 31 µg/ml and 62 µg/ml, respectively. Ethyl acetate extracts of Acacia nilotica and methanolic extract of E. globules also exhibited antibacterial activity against SMU and L. casei with MIC value of 50 µg/ml. Qualitative analysis of E. globules revealed the presence of alkaloids, terpenoids, phenolic compounds, and cardiac glycosides. The active principle responsible for the anticariogenic activity from E. globules were separated by TLC and subjected to bioautography using SMU, LA and LC. CONCLUSION: Anticariogenic activity and preliminary phytochemical analysis revealed that E. globule have potential to treat dental caries.