The Role of CLU1 in Maintaining Mitochondrial Genome Stability and Morphology in S. cerevisiae

Mitochondrial genome maintenance is essential for the normal function of the cell. Mitochondrial DNA (mtDNA) is located in the matrix, where it is in close proximity to the electron transport chain, which is within the inner mitochondrial membrane. During oxidative phosphorylation, the electron transport chain produces reactive oxygen species (ROS) that may damage the DNA and contribute to mutations within the genome. Mutations in the mitochondrial genome have long been hypothesized as a contributor to diseases, especially those of the neuromuscular system. Mitochondrial mutations have also been linked to some types of cancer, programmed cell death, and aging in humans. The ability to repair this damage is integral for cells to maintain proper fw1ction and longevity. S. cerevisiae is a facultative anaerobe that can grow in the absence of respiration under specific growth conditions, although mitochondria are still required for viability. The lab used a yeast two-hybrid assay with the known mitochondrial protein, Ilv5p, to isolate genes involved in the organization, repair, and recombination of mtDNA. The lab has identified the Clu1p in this screen. Clu1p function was previously found to be required for proper mitochondrial morphology and distribution (1). My thesis research has focused on creating clu1Δ strains and performing fluctuation analysis assays using different reporters that measure specific mitochondrial events. Initial characterization of CLU1 has shown that loss of Clu1p leads to an increased loss of mitochondrial function which may occur through various events, such as point mutations, recombinations or deletions, and DNA polymerase slippage. Microscopy has supported previous reports indicating that a clu1Δ strain displays a clustering phenotype (Fields et al. 1998). This deletion strain exhibits a branched mitochondrial network that is localized to one side within the yeast cell. These data provide evidence that Clu1p plays a central role in mitochondrial genome stability and morphology

CncC/Keap1 signaling pathway in the regulation of intestinal stem cells in Drosophila

Thesis (Ph. D.)--University of Rochester. Dept. of Biology, 2012.Organisms are faced with the challenge of maintaining tissue homeostasis despite various environmental and intracellular assaults that damage cells. Programmed cell death can eliminate cells that are no longer contributing to the proper function of a tissue. However, apoptosis without concomitant cell replacement over time would result in the loss of tissue and is not ideal for the overall health of the organism. Therefore, regenerative processes are critical in delaying the loss of tissue homeostasis that is characteristic of aging animals. In the adult metazoan, this goal is accomplished by pluripotent stem cells. How the regenerative capacity of stem cells changes in aging animals is the subject of intense investigation. The recent discovery of intestinal stem cells (ISCs) in the posterior midgut of Drosophila melanogaster has introduced this organism as a genetically amenable model for such studies. Antioxidant defenses and cytoprotective processes are believed to be critical for the maintenance of stem cell function. Here I present work which characterizes the role of a stress-responsive signaling pathway, NF-E2-related factor 2 [Nrf2(CncC in Drosophila)], in stem cell maintenance and regeneration of the intestinal epithelium of Drosophila. Using genetic and cellular biology approaches, I found Nrf2 to be a key regulator of ISC quiescence and also established cellular redox state, in general, as important for the control of ISC proliferation. Additional work presented in this dissertation will explore mechanisms of CncC regulation in ISCs in response to stress and a potential interaction between the CncC and Jun-N-terminal kinase (JNK) pathways. Furthermore, ISC proliferation will be investigated to determine the dynamics of stem cell quiescence in the adult intestinal epithelium. Together, these data demonstrate the importance of cellular redox state in the control of cellular processes and reveal a novel mechanism of stem cell and stem cell progenitor regulation by Nrf2

An environmental bacterial taxon with a large and distinct metabolic repertoire

Wilson MC, Mori T, Rückert C, et al. An environmental bacterial taxon with a large and distinct metabolic repertoire. Nature. 2014;506(7486):58-62.: Cultivated bacteria such as actinomycetes are a highly useful source of biomedically important natural products. However, such 'talented' producers represent only a minute fraction of the entire, mostly uncultivated, prokaryotic diversity. The uncultured majority is generally perceived as a large, untapped resource of new drug candidates, but so far it is unknown whether taxa containing talented bacteria indeed exist. Here we report the single-cell- and metagenomics-based discovery of such producers. Two phylotypes of the candidate genus 'Entotheonella' with genomes of greater than 9 megabases and multiple, distinct biosynthetic gene clusters co-inhabit the chemically and microbially rich marine sponge Theonella swinhoei. Almost all bioactive polyketides and peptides known from this animal were attributed to a single phylotype. 'Entotheonella' spp. are widely distributed in sponges and belong to an environmental taxon proposed here as candidate phylum 'Tectomicrobia'. The pronounced bioactivities and chemical uniqueness of 'Entotheonella' compounds provide significant opportunities for ecological studies and drug discovery