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Articles by G. A Caldwell
Total Records ( 2 ) for G. A Caldwell
  L. J Su , P. K Auluck , T. F Outeiro , E Yeger Lotem , J. A Kritzer , D. F Tardiff , K. E Strathearn , F Liu , S Cao , S Hamamichi , K. J Hill , K. A Caldwell , G. W Bell , E Fraenkel , A. A Cooper , G. A Caldwell , J. M McCaffery , J. C Rochet and S. Lindquist
  Linhui Julie Su, Pavan K. Auluck, Tiago Fleming Outeiro, Esti Yeger-Lotem, Joshua A. Kritzer, Daniel F. Tardiff, Katherine E. Strathearn, Fang Liu, Songsong Cao, Shusei Hamamichi, Kathryn J. Hill, Kim A. Caldwell, George W. Bell, Ernest Fraenkel, Antony A. Cooper, Guy A. Caldwell, J. Michael McCaffery, Jean-Christophe Rochet, and Susan Lindquist

-Synuclein (-syn) is a small lipid-binding protein involved in vesicle trafficking whose function is poorly characterized. It is of great interest to human biology and medicine because -syn dysfunction is associated with several neurodegenerative disorders, including Parkinson’s disease (PD). We previously created a yeast model of -syn pathobiology, which established vesicle trafficking as a process that is particularly sensitive to -syn expression. We also uncovered a core group of proteins with diverse activities related to -syn toxicity that is conserved from yeast to mammalian neurons. Here, we report that a yeast strain expressing a somewhat higher level of -syn also exhibits strong defects in mitochondrial function. Unlike our previous strain, genetic suppression of endoplasmic reticulum (ER)-to-Golgi trafficking alone does not suppress -syn toxicity in this strain. In an effort to identify individual compounds that could simultaneously rescue these apparently disparate pathological effects of -syn, we screened a library of 115,000 compounds. We identified a class of small molecules that reduced -syn toxicity at micromolar concentrations in this higher toxicity strain. These compounds reduced the formation of -syn foci, re-established ER-to-Golgi trafficking and ameliorated -syn-mediated damage to mitochondria. They also corrected the toxicity of -syn in nematode neurons and in primary rat neuronal midbrain cultures. Remarkably, the compounds also protected neurons against rotenone-induced toxicity, which has been used to model the mitochondrial defects associated with PD in humans. That single compounds are capable of rescuing the diverse toxicities of -syn in yeast and neurons suggests that they are acting on deeply rooted biological processes that connect these toxicities and have been conserved for a billion years of eukaryotic evolution. Thus, it seems possible to develop novel therapeutic strategies to simultaneously target the multiple pathological features of PD.

  S Cao , J. W Hewett , F Yokoi , J Lu , A. C Buckley , A. J Burdette , P Chen , F. C Nery , Y Li , X. O Breakefield , G. A Caldwell and K. A. Caldwell
  Songsong Cao, Jeffrey W. Hewett, Fumiaki Yokoi, Jun Lu, Amber Clark Buckley, Alexander J. Burdette, Pan Chen, Flavia C. Nery, Yuqing Li, Xandra O. Breakefield, Guy A. Caldwell, and Kim A. Caldwell

Movement disorders represent a significant societal burden for which therapeutic options are limited and focused on treating disease symptomality. Early-onset torsion dystonia (EOTD) is one such disorder characterized by sustained and involuntary muscle contractions that frequently cause repetitive movements or abnormal postures. Transmitted in an autosomal dominant manner with reduced penetrance, EOTD is caused in most cases by the deletion of a glutamic acid (E) in the DYT1 (also known as TOR1A) gene product, torsinA. Although some patients respond well to anticholingerics, therapy is primarily limited to either neurosurgery or chemodenervation. As mutant torsinA (E) expression results in decreased torsinA function, therapeutic strategies directed toward enhancement of wild-type (WT) torsinA activity in patients who are heterozygous for mutant DYT1 may restore normal cellular functionality. Here, we report results from the first-ever screen for candidate small molecule therapeutics for EOTD, using multiple activity-based readouts for torsinA function in Caenorhabditis elegans, subsequent validation in human DYT1 patient fibroblasts, and behavioral rescue in a mouse model of DYT1 dystonia. We exploited the nematode to rapidly discern chemical effectors of torsinA and identified two classes of antibiotics, quinolones and aminopenicillins, which enhance WT torsinA activity in two separate in vivo assays. Representative molecules were assayed in EOTD patient fibroblasts for improvements in torsinA-dependent secretory function, which was improved significantly by ampicillin. Furthermore, a behavioral defect associated with an EOTD mouse knock-in model was also rescued following administration of ampicillin. These combined data indicate that specific small molecules that enhance torsinA activity represent a promising new approach toward therapeutic development for EOTD, and potentially for other diseases involving the processing of mutant proteins.

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