In the mammalian genome, certain genomic loci/regions pose greater challenges to the DNA replication machinery (i.e., the replisome) than others. Such known genomic loci/regions include centromeres, common fragile sites, subtelomeres, and telomeres. However, the detailed mechanism of how mammalian cells cope with the replication stress at these loci/regions is largely unknown. Here we show that depletion of FANCM, or of one of its obligatory binding partners, FAAP24, MHF1, and MHF2, induces replication stress primarily at the telomeres of cells that use the alternative lengthening of telomeres (ALT) pathway as their telomere maintenance mechanism. Using the telomere-specific single-molecule analysis of replicated DNA technique, we found that depletion of FANCM dramatically reduces the replication efficiency at ALT telomeres. We further show that FANCM, BRCA1, and BLM are actively recruited to the ALT telomeres that are experiencing replication stress and that the recruitment of BRCA1 and BLM to these damaged telomeres is interdependent and is regulated by both ATR and Chk1. Mechanistically, we demonstrated that, in FANCM-depleted ALT cells, BRCA1 and BLM help to resolve the telomeric replication stress by stimulating DNA end resection and homologous recombination (HR). Consistent with their roles in resolving the replication stress induced by FANCM deficiency, simultaneous depletion of BLM and FANCM, or of BRCA1 and FANCM, leads to increased micronuclei formation and synthetic lethality in ALT cells. We propose that these synthetic lethal interactions can be explored for targeting the ALT cancers.aithfully replicating its genome is vital for the fitness and health of a mammalian cell. The replisome frequently encounters a variety of impediments throughout the genome. The temporary/transient slowing or stalling of the replication fork is referred to as replication stress (1, 2). The list of endogenous sources of replication stress is still growing. Nonetheless, the wellrecognized sources of replication stress include unrepaired DNA lesions, mis-incorporated ribonucleotides, unique DNA sequences that are prone to form secondary structures (e.g., G-quadruplex or G4), collision of the replication fork with the transcriptional machinery, an RNA-DNA hybrid (or R-loop) that is formed between a nascent RNA and the adjacent displaced single-stranded DNA (ssDNA), common fragile sites (CFS), and tightly packed genomic regions, such as heterochromatin (2). Because of these constant challenges faced by the replisome, mammalian cells have developed elaborate and complex strategies to resolve the replication stress and ensure the successful completion of DNA replication (1-4).One of the endogenous loci/regions that frequently pose challenges to the replisome is the telomere. Mammalian telomeres are tandem repetitive DNA sequences [the large majority as (TTAGGG) n ] located at the end of every linear chromosome. The addition of TTAGGG is catalyzed by an enzyme called telomerase, a large ribonucleoprotein complex with reverse tr...

Studies were undertaken to investigate the antiviral effects of comestible juices, especially cranberry juice, on non-related viral species. After exposure of bacteriophage T2 to a commercially available cranberry (Vaccinium macrocarpon) juice cocktail (CJ), virus infectivity titer was no longer detectible. After a 60-min exposure to orange (OJ) and grapefruit juices (GJ), phage infectivity was reduced to 25-35% of control, respectively. Similar data were observed for the bacteriophage T4. CJ inactivation of phage T4 was rapid, dose-dependent, and occurred at either 4 or 23 degrees C. Neither pH nor differences in sugar/carbohydrate levels among the juices may be ascribed to the recognized antiviral effects. Further studies were performed to identify the occurrence of antiviral activity by CJ to a mammalian enteric virus. The treatment of the simian rotavirus SA-11 with a 20% CJ suspension was sufficient to inhibit hemagglutination. Under scanning and transmission electron microscopy, CJ was observed to inhibit the adsorption of phage T4 to its bacterial host cells and prevented the replication of rotavirus in its monkey kidney (MA-104) host cells, respectively. The data suggest, for the first time, a non-specific antiviral effect towards unrelated viral species (viz., bacteriophages T2 and T4 and the simian rotavirus SA-11) by a commercially available cranberry fruit juice drink.

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