Mouse Anti Chicken L1-like CAM (avian) Hybridoma [9E0]

RATIONALEThe N-myc gene is a member of the MYC family and its amplification is highly correlated with the pathophysiology of cancers. The G-rich sequence, d(AG(3)CG(3)AG(3)AG(3)A), in the first intron of N-myc can form a G-quadruplex structure. Small molecules binding to it with high affinity and selectivity may provide a potential approach to modulate the expression of the N-myc gene. METHODSElectrospray ionization (ESI) mass spectrometry was used to analyze the G-quadruplex formation of the d(AG(3)CG(3)AG(3)AG(3)A) sequence, and to evaluate the binding affinities and selectivities of natural small molecules with the N-myc G-quadruplex. RESULTSEnniatin B was found to have the highest binding affinity with this G-quadruplex within the 12 small molecules. Moreover, it also showed a biased selectivity toward the N-myc G-quadruplex compared with the other five G-quadruplexes derived from C-myc, Bcl2, Chl1, c-kit promoters and telomere G-rich sequences. CONCLUSIONSIn this study, we found a natural small molecule, enniatin B, which could bind to the G-quadruplex of the d(AG(3)CG(3)AG(3)AG(3)A) sequence from the first intron of the N-myc gene with high affinity and selectivity, which may lead to a potential modulation of the N-myc gene. Copyright (c) 2014 John Wiley & Sons, Ltd.

Helicases are components of numerous protein complexes, including those regulating transcription, translation, DNA replication and repair, splicing, and mitotic chromosome transmission. Helicases unwind double-stranded DNA and RNA homo- and hetero-duplexes. The yeast CHL1 helicase has been linked to maintenance of the high fidelity of chromosome transmission during mitosis. Mutations in this gene result in a 200-fold increase in the rate of aberrant chromosome segregation with a concomitant delay in the cell cycle at G(2)-M, suggesting that CHL1 is required for the maintenance of proper chromosome transmission, Two highly related human cDNA clones encoding proteins which are homologous to the yeast CHL1 gene product have been isolated, Here we show that these two distinct human CHL1-related mRNAs and proteins (hCHLR1 and hCHLR2) are expressed only in proliferating human cell lines, Quiescent normal human fibroblasts stimulated to re-enter the cell cycle by addition of serum begin to express the CHL1-related proteins as the cells enter S phase, concomitant with the expression of proliferating cell nuclear antigen, Furthermore, expression of the CHL1-related mRNAs is lost when human K562 cells cease to proliferate and terminally differentiate in response to phorbol ester treatments. Human hCHLR expression is not extinguished during hemin-induced differentiation of the same cell line, which produces erythrocyte-like cells that continue to proliferate. These experiments are consistent with the requirement of this putative helicase during either S or G(2)-M phase but not G(1). In vitro transcribed and translated hCHLR1 protein binds to both single- and double-stranded DNA, supporting the possibility that these proteins are DNA helicases. Finally, affinity-purified hCHLR1 antisera was used to demonstrate the localization of the hCHLR proteins to the nucleolus by indirect immunofluorescence as well as by cell fractionation.