http://hdl.handle.net/1957/22171 2013-05-19T21:00:04Z 2013-05-19T21:00:04Z Mannava, Sudha Moparthy, Kalyana C. Wheeler, Linda J. Leonova, Katerina I. Wawrzyniak, Joseph A. Bianchi-Smiraglia, Anna Berman, Albert E. Flanagan, Sheryl Shewach, Donna S. Zeitouni, Nathalie C. Gudkov, Andrei V. Mathews, Christopher K. Nikiforov, Mikhail A. http://hdl.handle.net/1957/38287 2013-04-22T20:38:15Z 2012-12-01T00:00:00Z

Ribonucleotide reductase and thymidylate synthase or exogenous deoxyribonucleosides reduce DNA damage and senescence caused by C‐MYC depletion Mannava, Sudha; Moparthy, Kalyana C.; Wheeler, Linda J.; Leonova, Katerina I.; Wawrzyniak, Joseph A.; Bianchi-Smiraglia, Anna; Berman, Albert E.; Flanagan, Sheryl; Shewach, Donna S.; Zeitouni, Nathalie C.; Gudkov, Andrei V.; Mathews, Christopher K.; Nikiforov, Mikhail A. The down‐regulation of dominant oncogenes, including C‐MYC, in tumor cells often leads to the induction of senescence via mechanisms that are not completely identified. In the current study, we demonstrate that MYC‐depleted melanoma cells undergo extensive DNA damage that is caused by the underexpression of thymidylate synthase (TS) and ribonucleotide reductase (RR) and subsequent depletion of deoxyribonucleoside triphosphate pools. Simultaneous genetic inhibition of TS and RR in melanoma cells induced DNA damage and senescence phenotypes very similar to the ones caused by MYC‐depletion. Reciprocally, overexpression of TS and RR in melanoma cells or addition of deoxyribonucleosides to culture media substantially inhibited DNA damage and senescence‐associated phenotypes caused by C‐MYC depletion. Our data demonstrate the essential role of TS and RR in C‐MYC‐dependent suppression of senescence in melanoma cells. This is the publisher’s final pdf. The published article is copyrighted by Impact Journals LLC. and can be found at: http://www.impactaging.com/index.html.

2012-12-01T00:00:00Z Saldivar, Joshua C. Miuma, Satoshi Bene, Jessica Hosseini, Seyed Ali Shibata, Hidetaka Sun, Jin Wheeler, Linda J. Mathews, Christopher K. Huebner, Kay http://hdl.handle.net/1957/37950 2013-04-02T18:12:47Z 2012-11-29T00:00:00Z

Initiation of Genome Instability and Preneoplastic Processes through Loss of Fhit Expression Saldivar, Joshua C.; Miuma, Satoshi; Bene, Jessica; Hosseini, Seyed Ali; Shibata, Hidetaka; Sun, Jin; Wheeler, Linda J.; Mathews, Christopher K.; Huebner, Kay Genomic instability drives tumorigenesis, but how it is initiated in sporadic neoplasias is unknown. In early preneoplasias, alterations at chromosome fragile sites arise due to DNA replication stress. A frequent, perhaps earliest, genetic alteration in preneoplasias is deletion within the fragile FRA3B/FHIT locus, leading to loss of Fhit protein expression. Because common chromosome fragile sites are exquisitely sensitive to replication stress, it has been proposed that their clonal alterations in cancer cells are due to stress sensitivity rather than to a selective advantage imparted by loss of expression of fragile gene products. Here, we show in normal, transformed, and cancer-derived cell lines that Fhit-depletion causes replication stress-induced DNA double-strand breaks. Using DNA combing, we observed a defect in replication fork progression in Fhit-deficient cells that stemmed primarily from fork stalling and collapse. The likely mechanism for the role of Fhit in replication fork progression is through regulation of Thymidine kinase 1 expression and thymidine triphosphate pool levels; notably, restoration of nucleotide balance rescued DNA replication defects and suppressed DNA breakage in Fhit-deficient cells. Depletion of Fhit did not activate the DNA damage response nor cause cell cycle arrest, allowing continued cell proliferation and ongoing chromosomal instability. This finding was in accord with in vivo studies, as Fhit knockout mouse tissue showed no evidence of cell cycle arrest or senescence yet exhibited numerous somatic DNA copy number aberrations at replication stress-sensitive loci. Furthermore, cells established from Fhit knockout tissue showed rapid immortalization and selection of DNA deletions and amplifications, including amplification of the Mdm2 gene, suggesting that Fhit loss-induced genome instability facilitates transformation. We propose that loss of Fhit expression in precancerous lesions is the first step in the initiation of genomic instability, linking alterations at common fragile sites to the origin of genome instability. This is the publisher’s final pdf. The published article is copyrighted by Public Library of Science and can be found at: http://www.plos.org/.

2012-11-29T00:00:00Z Campbell, Yan Fantacone, Mary L. Gombart, Adrian F. http://hdl.handle.net/1957/37897 2013-03-27T23:17:50Z 2012-12-01T00:00:00Z

Regulation of antimicrobial peptide gene expression by nutrients and byproducts of microbial metabolism Campbell, Yan; Fantacone, Mary L.; Gombart, Adrian F. Background: Antimicrobial peptides (AMPs) are synthesized and secreted by immune and epithelial cells that are constantly exposed to environmental microbes. AMPs are essential for barrier defense and deficiencies lead to increased susceptibility to infection. In addition to their ability to disrupt the integrity of bacterial, viral and fungal membranes, AMPs bind lipopolysaccharides, act as chemoattractants for immune cells and bind to cellular receptors and modulate the expression of cytokines and chemokines. These additional biological activities may explain the role of AMPs in inflammatory diseases and cancer. Modulating the endogenous expression of AMPs offers potential therapeutic treatments for infection and disease. Methods: The present review examines published data from both in vitro and in vivo studies reporting effects of nutrients and byproducts of microbial metabolism on the expression of antimicrobial peptide genes in order to highlight an emerging appreciation for the role of dietary compounds in modulating the innate immune response. Results: Vitamins A and D, dietary histone deacetylases and byproducts of intestinal microbial metabolism (butyrate and secondary bile acids) have been found to regulate the expression of AMPs in humans. Vitamin D deficiency correlates with increased susceptibility to infection and supplementation studies indicate an improvement in defense against infection. Animal and human clinical studies with butyrate indicate that increasing expression of AMPs in the colon protects against infection. Conclusion: These findings suggest that diet and/or consumption of nutritional supplements may be used to improve and/or modulate immune function. In addition, byproducts ofgut microbe metabolism could be important for communicating with intestinal epithelial and immune cells, thus affecting the expression of AMPs. This interaction may help establish a mucosal barrier to prevent invasion of the intestinal epithelium by either mutualistic or pathogenic microorganisms. This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/394.

2012-12-01T00:00:00Z Karimi-Aghcheh, Razieh Bok, Jin Woo Phatale, Pallavi A. Smith, Kristina M. Baker, Scott E. Lichius, Alexander Omann, Markus Zeilinger, Susanne Seiboth, Bernhard Rhee, Catherine Keller, Nancy P. Freitag, Michael Kubicek, Christian P. http://hdl.handle.net/1957/37531 2013-03-18T16:40:03Z 2013-02-01T00:00:00Z

Functional Analyses of Trichoderma reesei LAE1 Reveal Conserved and Contrasting Roles of This Regulator Karimi-Aghcheh, Razieh; Bok, Jin Woo; Phatale, Pallavi A.; Smith, Kristina M.; Baker, Scott E.; Lichius, Alexander; Omann, Markus; Zeilinger, Susanne; Seiboth, Bernhard; Rhee, Catherine; Keller, Nancy P.; Freitag, Michael; Kubicek, Christian P. The putative methyltransferase LaeA is a global regulator that affects the expression of multiple secondary metabolite gene clusters in several fungi, and it can modify heterochromatin structure in Aspergillus nidulans. We have recently shown that the LaeA ortholog of Trichoderma reesei (LAE1), a fungus that is an industrial producer of cellulase and hemicellulase enzymes, regulates the expression of cellulases and polysaccharide hydrolases. To learn more about the function of LAE1 in T. reesei, we assessed the effect of deletion and overexpression of lae1 on genome-wide gene expression. We found that in addition to positively regulating 7 of 17 polyketide or nonribosomal peptide synthases, genes encoding ankyrin-proteins, iron uptake, heterokaryon incompatibility proteins, PTH11-receptors, and oxidases/monoxygenases are major gene categories also regulated by LAE1. chromatin immunoprecipitation sequencing with antibodies against histone modifications known to be associated with transcriptionally active (H3K4me2 and -me3) or silent (H3K9me3) chromatin detected 4089 genes bearing one or more of these methylation marks, of which 75 exhibited a correlation between either H3K4me2 or H3K4me3 and regulation by LAE1. Transformation of a laeA-null mutant of A. nidulans with the T. reesei lae1 gene did not rescue sterigmatocystin formation and further impaired sexual development. LAE1 did not interact with A. nidulans VeA in yeast two-hybrid assays, whereas it interacted with the T. reesei VeA ortholog, VEL1. LAE1 was shown to be required for the expression of vel1, whereas the orthologs of velB and VosA are unaffected by lae1 deletion. Our data show that the biological roles of A. nidulans LaeA and T. reesei LAE1 are much less conserved than hitherto thought. In T. reesei, LAE1 appears predominantly to regulate genes increasing relative fitness in its environment. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by The Genetics Society of America and can be found at: http://www.genetics-gsa.org/.

2013-02-01T00:00:00Z