East Carolina University : Research and Creative Achievement Week 2012
molecular order upon formation of lipid rafts. Additional in vitro treatments showed that DHA, but not EPA treatment increased molecular order. Biochemical measurements revealed raft-like membrane fractions had increased levels of DHA in phosphatidylcholines but not phosphatidylethanolamines. Finally we verified that the fish oil diet was immunosuppressive. We measured decreased IL-2 secretion from T cells activated by diet modified B cells. All together, this study supports the mechanism that n-3 PUFAs can modify lipid raft domains potentially leading to immunosuppression. Furthermore, the data expand the focus into an additional cell type which could ultimately help shape dietary recommendations of fish oil for potential treatment of chronic inflammatory disorders. Irr is the main iron responsive transcriptional regulator in Brucella abortus, David A. Martinson, R.M. Roop II Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27858 Members of the genus Brucella belong to the alpha-proteobacteria group of Gram negative bacteria. As an intracellular pathogen, B. abortus must overcome iron sequestration in the host cell by utilizing highly efficient iron transport systems. These systems must be regulated, however, as excess intracellular iron is toxic to the bacterial cells. Most of the alphaproteobacteria rely on a transcriptional regulator known as the iron response regulator (Irr) to control the expression of their iron metabolism genes. Irr serves as an activator of genes involved in iron acquisition and represses the transcription of genes encoding products that require high levels of iron for their function (e.g. heme biosynthesis genes). An isogenic B. abortus irr mutant produces significantly less siderophore molecules when grown under iron limiting conditions compared to the wild type strain. Intracellular iron levels are also lower in an irr mutant than that in the wild type strain. We are currently utilizing Real-time RT PCR and microarray analysis to determine which specific genes are mis-regulated in an irr mutant. Electrophoretic mobility shift assays are being used to determine the ability of Irr to directly regulate these genes by binding to their promoter regions. The ability of Irr to respond to intracellular iron levels is unique, in that when intracellular iron levels are high, Irr is degraded and can no longer function as a transcriptional regulator. An internal HXH heme binding motif that is highly conserved among the alpha-proteobacteria is required for iron dependent degradation of Irr in B. abortus. We are presently exploring the mechanism behind the HXH dependent iron responsive degradation of Irr in B. abortus in an effort to better understand how Irr coordinates the expression of iron metabolism genes.
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Injury-induced miR-431 promotes axon growth in murine dorsal root ganglion neurons, Di Wu, Elena Pak and Alexander Murashov, Department of Physiology, East Carolina University, Greenville, NC 27834 microRNAs (miRNAs) are small, non-coding RNAs that function as important posttranscriptional regulators in several developmental and physiological processes. Dysregulation of miRNAs have been implicated in many neurological disorders, such as Alzheimer's disease and Parkinson's disease. Compelling evidences also linked miRNA pathway to the regulation of neurodevelopment, neurogenesis, synaptic plasticity, and neural repairs. The investigation of miRNAs expression and function has important implications for understanding molecular mechanism and developing potential therapeutic strategies for neurological diseases. Our previous work showed that peripheral nerve axons in vivo and in vitro contain functional miRNA machinery that would respond to peripheral nerve injury. In addition, we demonstrated 83
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