@article{ThoelkenThammErbacheretal.2019,
  author    = {Th{\"o}lken, Clemens and Thamm, Markus and Erbacher, Christoph and Lechner, Marcus},
  title     = {Sequence and structural properties of circular RNAs in the brain of nurse and forager honeybees (Apis mellifera)},
  series = {BMC Genomics},
  volume    = {20},
  journal   = {BMC Genomics},
  doi       = {10.1186/s12864-018-5402-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-241302},
  year      = {2019},
  abstract  = {Background The honeybee (Apis mellifera) represents a model organism for social insects displaying behavioral plasticity. This is reflected by an age-dependent task allocation. The most protruding tasks are performed by young nurse bees and older forager bees that take care of the brood inside the hive and collect food from outside the hive, respectively. The molecular mechanism leading to the transition from nurse bees to foragers is currently under intense research. Circular RNAs, however, were not considered in this context so far. As of today, this group of non-coding RNAs was only known to exist in two other insects, Drosophila melanogaster and Bombyx mori. Here we complement the state of circular RNA research with the first characterization in a social insect. Results We identified numerous circular RNAs in the brain of A. mellifera nurse bees and forager bees using RNA-Seq with exonuclease enrichment. Presence and circularity were verified for the most abundant representatives. Back-splicing in honeybee occurs further towards the end of transcripts and in transcripts with a high number of exons. The occurrence of circularized exons is correlated with length and CpG-content of their flanking introns. The latter coincides with increased DNA-methylation in the respective loci. For two prominent circular RNAs the abundance in worker bee brains was quantified in TaqMan assays. In line with previous findings of circular RNAs in Drosophila, circAmrsmep2 accumulates with increasing age of the insect. In contrast, the levels of circAmrad appear age-independent and correlate with the bee's task. Its parental gene is related to amnesia-resistant memory. Conclusions We provide the first characterization of circRNAs in a social insect. Many of the RNAs identified here show homologies to circular RNAs found in Drosophila and Bombyx, indicating that circular RNAs are a common feature among insects. We find that exon circularization is correlated to DNA-methylation at the flanking introns. The levels of circAmrad suggest a task-dependent abundance that is decoupled from age. Moreover, a GO term analysis shows an enrichment of task-related functions. We conclude that circular RNAs could be relevant for task allocation in honeybee and should be investigated further in this context.},
  language  = {en}
}
@phdthesis{Akimzhanov2005,
  author    = {Akimzhanov, Askar M.},
  title     = {Epigenetic repression of the NFATc1 transcription factor in human lymphomas},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-12921},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {We examined the regulation of NFATc1 in different lymphomas and observed an inversed correlation between the methylation status and expression of NFATc1. Our data demonstrate that aberrant DNA methylation associated with chromatin remodeling within nfatc1 locus is a major mechanism for the repression of NFATc1 expression, suggesting that the DNA methylation-mediated transcriptional silencing of NFATc1 may be a critical event in the tumorogenesis of ALCLs and cHLs. Furthermore, the DNA methylation of human nfatc1 promoter region could be used as a novel biomarker of tumor progression. Our results indicate a close link between the loss of immunoreceptor signaling and NFATc1 expression in human lymphomas. For both ALCLs and cHLs, defects in immunoreceptor signaling have been described which result in a loss of receptor-mediated gene expression programs (Schwering et al., 2003; Bonzheim et al., 2004; Marafioti et al., 2004). In T cells, one indicator gene of these programs appears to be the nfatc1 gene whose expression is controlled by TCR signals (Chuvpilo et al., 2002a). In contrast, in T cells NFATc1 expression is unaffected by TCR signals, and NFATc2 was found to be expressed at normal levels in ALCLs and cHLs (L.K., unpubl. data). Moreover, the activity of NF-kappaB factors which can bind to certain NFAT binding sites and share a distantly-related DNA binding domain with NFATs is strongly elevated in cHL cells (Bargou et al., 1997; Hinz et al., 2001; Hinz et al., 2002) suggesting that NFATs and NF-kappaBs exert very different effects on generation and maintenance of Hodgkin's lymhomas. However, it should be mentioned that in Burkitt's and further B cell lymphomas in which NFATc1 proteins are strongly expressed and controlled by receptor signals (Kondo et al., 2003), they could exert a promoting function in tumor development. The genes of p53 family members p63 and p73 are prominent examples for mammalian genes whose products can act both as oncoproteins and tumor suppressor genes (Hibi et al., 2000; Stiewe and Putzer, 2002), and it is likely that more genes exist which encode both tumor suppressors and oncoproteins. It remains to be shown whether the nfatc1 gene is one of them.},
  subject      = {Lymphom},
  language  = {en}
}