n-Butyllithium-Induced Tandem [3,3]-Sigmatropic Rearrangement and Carbonyl Olefination of Allyl-1,1-dichlorovinyl Ethers.

Exposure of dichlorovinyl ethers 1 to n-butyllithium and addition of saturated or unsaturated aldehydes, ketones, or esters at ambient temperature furnishes rearranged α,ß-unsaturated carboxylic acids, isolated as their corresponding methyl esters 2 in 48-91% overall yields. Exposure of dichlorovinyl ethers 1 to n-butyllithium, addition of aldehydes, ketones, dialdehydes, or diketones at -78 °C, and warming to 80 °C in the presence of SiO2 provide 1,4-dienes 3 or cycloalken-1-ols (or their dehydration products) 4 in 45-72% overall yields.

In Vivo Functional Platform Targeting Patient-Derived Xenografts Identifies WDR5-Myc Association as a Critical Determinant of Pancreatic Cancer.

Current treatment regimens for pancreatic ductal adenocarcinoma (PDAC) yield poor 5-year survival, emphasizing the critical need to identify druggable targets essential for PDAC maintenance. We developed an unbiased and in vivo target discovery approach to identify molecular vulnerabilities in low-passage and patient-derived PDAC xenografts or genetically engineered mouse model-derived allografts. Focusing on epigenetic regulators, we identified WDR5, a core member of the COMPASS histone H3 Lys4 (H3K4) MLL (1-4) methyltransferase complex, as a top tumor maintenance hit required across multiple human and mouse tumors. Mechanistically, WDR5 functions to sustain proper execution of DNA replication in PDAC cells, as previously suggested by replication stress studies involving MLL1, and c-Myc, also found to interact with WDR5. We indeed demonstrate that interaction with c-Myc is critical for this function. By showing that ATR inhibition mimicked the effects of WDR5 suppression, these data provide rationale to test ATR and WDR5 inhibitors for activity in this disease.

Low temperature n-butyllithium-induced [3,3]-sigmatropic rearrangement/electrophile trapping reactions of allyl-1,1-dichlorovinyl ethers. Synthesis of ß-, γ- and δ-lactones.

Treatment of allyl-1,1-dichlorovinyl ethers with n-BuLi at -78 °C, followed by quenching with ketones, epoxides, and oxetanes, leads to highly substituted ß-, γ-, and δ-lactones in good to excellent yields.

A cis-regulatory map of the Drosophila genome.

Systematic annotation of gene regulatory elements is a major challenge in genome science. Direct mapping of chromatin modification marks and transcriptional factor binding sites genome-wide has successfully identified specific subtypes of regulatory elements. In Drosophila several pioneering studies have provided genome-wide identification of Polycomb response elements, chromatin states, transcription factor binding sites, RNA polymerase II regulation and insulator elements; however, comprehensive annotation of the regulatory genome remains a significant challenge. Here we describe results from the modENCODE cis-regulatory annotation project. We produced a map of the Drosophila melanogaster regulatory genome on the basis of more than 300 chromatin immunoprecipitation data sets for eight chromatin features, five histone deacetylases and thirty-eight site-specific transcription factors at different stages of development. Using these data we inferred more than 20,000 candidate regulatory elements and validated a subset of predictions for promoters, enhancers and insulators in vivo. We identified also nearly 2,000 genomic regions of dense transcription factor binding associated with chromatin activity and accessibility. We discovered hundreds of new transcription factor co-binding relationships and defined a transcription factor network with over 800 potential regulatory relationships.

A streptococcal effector protein that inhibits Porphyromonas gingivalis biofilm development.

Dental plaque formation is a developmental process involving cooperation and competition within a diverse microbial community, approximately 70 % of which is composed of an array of streptococci during the early stages of supragingival plaque formation. In this study, 79 cell-free culture supernatants from a variety of oral streptococci were screened to identify extracellular compounds that inhibit biofilm formation by the oral anaerobe Porphyromonas gingivalis strain 381. The majority of the streptococcal supernatants (61 isolates) resulted in lysis of P. gingivalis cells, and some (17 isolates) had no effect on cell viability, growth or biofilm formation. One strain, however, produced a supernatant that abolished biofilm formation without affecting growth rate. Analysis of this activity led to the discovery that a 48 kDa protein was responsible for the inhibition. Protein sequence identification and enzyme activity assays identified the effector protein as an arginine deiminase. To identify the mechanism(s) by which this protein inhibits biofilm formation, we began by examining the expression levels of genes encoding fimbrial subunits; surface structures known to be involved in biofilm development. Quantitative RT-PCR analysis revealed that exposure of P. gingivalis cells to this protein for 1 h resulted in the downregulation of genes encoding proteins that are the major subunits of two distinct types of thin, single-stranded fimbriae (fimA and mfa1). Furthermore, this downregulation occurred in the absence of arginine deiminase enzymic activity. Hence, our data indicate that P. gingivalis can sense this extracellular protein, produced by an oral streptococcus (Streptococcus intermedius), and respond by downregulating expression of cell-surface appendages required for attachment and biofilm development.

Low-temperature n-butyllithium-induced rearrangement of allyl 1,1-dichlorovinyl ethers.

[reaction: see text]. Upon treatment with n-BuLi at low temperatures, a variety of allyl 1,1-dichlorovinyl ethers 2 undergo rearrangement to furnish gamma,delta-unsaturated esters 3 after alcohol addition. Compounds containing quaternary centers (3e: R1 = H, R2, R3 = -(CH2)5-; 3f: R1 = H, R2 = CH3, R3 = (CH2)2CH(CH3)2) may be formed in high yield and under mild conditions utilizing this protocol. The reaction is stereospecific and may be applied to the preparation of Delta(2,3)-beta-C-glycosides and alpha,beta-disubstituted lactones.