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McFedries, Amanda

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McFedries

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Amanda

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McFedries, Amanda
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    Deletion of Prepl Causes Growth Impairment and Hypotonia in Mice
    (Public Library of Science, 2014) Lone, Anna Mari; Leidl, Mathias; McFedries, Amanda; Horner, James W.; Creemers, John; Saghatelian, Alan
    Genetic studies of rare diseases can identify genes of unknown function that strongly impact human physiology. Prolyl endopeptidase-like (PREPL) is an uncharacterized member of the prolyl peptidase family that was discovered because of its deletion in humans with hypotonia-cystinuria syndrome (HCS). HCS is characterized by a number of physiological changes including diminished growth and neonatal hypotonia or low muscle tone. HCS patients have deletions in other genes as well, making it difficult to tease apart the specific role of PREPL. Here, we develop a PREPL null (PREPL−/−) mouse model to address the physiological role of this enzyme. Deletion of exon 11 from the Prepl gene, which encodes key catalytic amino acids, leads to a loss of PREPL protein as well as lower Prepl mRNA levels. PREPL−/− mice have a pronounced growth phenotype, being significantly shorter and lighter than their wild type (PREPL+/+) counterparts. A righting assay revealed that PREPL−/− pups took significantly longer than PREPL+/+ pups to right themselves when placed on their backs. This deficit indicates that PREPL−/− mice suffer from neonatal hypotonia. According to these results, PREPL regulates growth and neonatal hypotonia in mice, which supports the idea that PREPL causes diminished growth and neonatal hypotonia in humans with HCS. These animals provide a valuable asset in deciphering the underlying biochemical, cellular and physiological pathways that link PREPL to HCS, and this may eventually lead to new insights in the treatment of this disease.
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    Characterization of Protein-Metabolite and Protein-Substrate Interactions of Disease Genes
    (2014-06-06) McFedries, Amanda; Saghatelian, Alan; Liu, David Ruchien; Gray, Nathanael; Leschziner, Andres Leschziner
    Discovery of protein-metabolite and protein-substrate interactions that can specifically regulate genes involved in human biology is an important pursuit, as the study of such interactions can expand our understanding of human physiology and reveal novel therapeutic targets. The identification and characterization of these interactions can be approached from different perspectives. Chemists often use bioactive small molecules, such as natural products or synthetic compounds, as probes to identify therapeutically relevant protein targets. Biochemists and biologists often begin with a specific protein and seek to identify the endogenous ligands that bind to it. These interests have led to the development of methodology that relies heavily on synthetic and analytical chemistry to identify interactions, an approach that is complemented by in vivo strategies for validating the biological consequences of specific interactions.
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    Anti-diabetic activity of insulin-degrading enzyme inhibitors mediated by multiple hormones
    (Nature Publishing Group, 2014) Maianti, Juan; McFedries, Amanda; Foda, Zachariah H.; Kleiner, Ralph; Du, Xiu Quan; Leissring, Malcolm A.; Tang, Wei-Jen; Charron, Maureen J.; Seeliger, Markus A.; Saghatelian, Alan; Liu, David
    Despite decades of speculation that inhibiting endogenous insulin degradation might treat type-2 diabetes, and the identification of IDE (insulin-degrading enzyme) as a diabetes susceptibility gene, the relationship between the activity of the zinc metalloprotein IDE and glucose homeostasis remains unclear. Although Ide −/− mice have elevated insulin levels, they exhibit impaired, rather than improved, glucose tolerance that may arise from compensatory insulin signalling dysfunction. IDE inhibitors that are active in vivo are therefore needed to elucidate IDE’s physiological roles and to determine its potential to serve as a target for the treatment ofdiabetes. Here we report the discovery of a physiologically active IDE inhibitor identified from a DNA-templated macrocycle library. An X-ray structure of the macrocycle bound to IDE reveals that it engages a binding pocket away from the catalytic site, which explains its remarkable selectivity. Treatment of lean and obese mice with this inhibitor shows that IDE regulates the abundance and signalling of glucagon and amylin, in addition to that of insulin. Under physiological conditions that augment insulin and amylin levels, such as oral glucose administration, acute IDE inhibition leads to substantially improved glucose tolerance and slower gastric emptying. These findings demonstrate the feasibility of modulating IDE activity as a new therapeutic strategy to treat type-2 diabetes and expand our understanding of the roles of IDE in glucose and hormone regulation.