Browsing by Subject "neurotoxicity"

Now showing 1 - 5 of 5
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    The Impact of SBF2 on Taxane-Induced Peripheral Neuropathy
    (2021-05) Cunningham, Geneva Mari; Schneider, Bryan P.; Radovich, Milan; Liu, Yunlong; Skaar, Todd; Meyer, Jason; Ivan, Mircea
    The main focus of this study is to determine the impact of Set-Binding Factor 2 (SBF2) on human-derived neurons in the context of taxane-induced peripheral neuropathy. Taxane-induced peripheral neuropathy (TIPN) is a devastating survivorship issue for many cancer patients; SBF2 has been previously identified as a potential germline predictor that has been found to be significantly associated with severe TIPN in African American (AA) patients. The work described here provides ex vivo support for the use of SBF2 as a genotypic biomarker to identify a priori which patients are at a higher risk of manifesting severe TIPN. This study demonstrates that diminished expression of SBF2 exacerbated the effect of paclitaxel on viability and morphology and altered the functional response of a neuronal model exposed to paclitaxel treatment. Furthermore, transcriptomic work showed that reduced expression of SBF2 in a neuronal model treated with paclitaxel impacted the expression of genes that modulate stress-induced cell death and pain threshold. Altogether, these findings suggest that SBF2 plays a role in the development of TIPN. This work sheds light on the pathways potentially involving SBF2 that can be studied to further evaluate the function of this gene in neurons and its contribution to severe TIPN. Further functional approaches investigating these pathways will be pivotal in elucidating the underlying biological mechanism for this toxicity and identifying novel targeted therapeutic strategies to prevent or treat TIPN.
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    Implications of Ape1 in reactive oxygen signaling response following cisplatin treatment of dorsal root ganglion neurons
    (2008-08) Jiang, Yanlin; Guo, Chunlu; Vasko, Michael R.; Kelley, Mark R.
    Peripheral neuropathy is one of the major side-effects of the anticancer drug, cisplatin. Although previous work suggests that this neuropathy correlates with formation of DNA adducts in sensory neurons, growing evidence suggests that cisplatin also increases the generation of reactive oxygen species (ROS), which could cause DNA damage. Apurinic/apyrimidinic endonuclease/redox factor-1 (Ape1/Ref-1) is a multifunctional protein involved in DNA base excision repair (BER) of oxidative DNA damage and in redox regulation of a number of transcription factors. Therefore, we asked whether altering Ape1 functions would influence cisplatin induced neurotoxicity. Sensory neurons in culture were exposed to cisplatin for 24 hrs and several endpoints of toxicity were measured including production of ROS, cell death, apoptosis, and release of the immunoreactive calcitonin gene-related peptide (iCGRP). Reducing expression of Ape1 in neuronal cultures using siRNA enhances cisplatin-induced cell killing, apoptosis, ROS generation and the cisplatin-induced reduction in iCGRP release. Overexpressing wild-type (WT)-Ape1 attenuates all the toxic effects of cisplatin in cells containing normal endogenous levels of Ape1 and in cells with reduced Ape1 levels following Ape1siRNA treatment. Overexpressing the redox deficient/repair competent C65-Ape1 provides partial rescue, while the repair deficient Ape1 (N226A+R177A) does not protect neurons from cisplatin toxicity. We also observe an increase in phosphorylation of p53 following a decrease in Ape1 levels in sensory neuronal cultures. These results strongly support the notion that Ape1 is a potential translational target such that protecting Ape1 levels and particularly its DNA repair function could reduce peripheral neuropathy in patients undergoing cisplatin treatment.
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    Neurotoxicity to dopamine neurons after the serial exposure to alcohol and methamphetamine: Protection by COX-2 antagonism
    (Elsevier, 2019) Blaker, Amanda L.; Rodriguez, Eric A.; Yamamoto, Bryan K.; Pharmacology and Toxicology, School of Medicine
    A significant co-morbidity exists between alcohol and methamphetamine (Meth) in humans but the consequences and mechanisms underlying their co-morbid effects remain to be identified. A consequence associated with the abuse of either alcohol or Meth involves inflammation but little is known about the role of inflammation in a possible neurotoxicity arising from their co-exposure. Sprague Dawley rats were allowed 28 days of intermittent, voluntary access to 10% ethanol (EtOH) followed by a neurotoxic binge administration of Meth. EtOH drinking followed by Meth increased microglial cell counts and produced morphological changes in microglia of the substantia nigra pars compacta 2 h after Meth administration that were distinct from those produced by either EtOH or Meth alone. These effects preceded the activation of cleaved caspase-3 in dopamine cell bodies, as well as decreases in tyrosine hydroxylase (TH) immunoreactivity in the substantia nigra and dopamine transporter (DAT) immunoreactivity in the striatum measured at 7 days after Meth. Intervention with a selective COX-2 inhibitor during EtOH drinking prevented the changes in microglia, and attenuated the increase in cleaved caspase-3, and decreases in TH and DAT after Meth administration. Furthermore, motor dysfunction measured by a rotarod test was evident but only in rats that were exposed to both EtOH and Meth. The motor dysfunction was ameliorated by prior inhibition of COX-2 during EtOH drinking. The exaggerated neurochemical and behavioral deficits indicate that the comorbidity of EtOH and Meth induces a degeneration of the nigrostriatal pathway and support the role of inflammation produced by EtOH drinking that primes and mediates the neurotoxic consequences associated with the common co-morbidity of these drugs.
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    The putative multidrug resistance protein MRP-7 inhibits methylmercury-associated animal toxicity and dopaminergic neurodegeneration in Caenorhabditis elegans
    (Wiley, 2014-03) VanDuyn, Natalia; Nass, Richard; Department of Pharmacology and Toxicology, IU School of Medicine
    Parkinson’s disease (PD) is the most prevalent neurodegenerative motor disorder worldwide, and results in the progressive loss of dopamine (DA) neurons in the substantia nigra pars compacta. Gene-environment interactions are believed to play a significant role in the vast majority of PD cases, yet the toxicants and the associated genes involved in the neuropathology are largely ill-defined. Recent epidemiological and biochemical evidence suggests that methylmercury (MeHg) may be an environmental toxicant that contributes to the development of PD. Here we report that a gene coding for the putative multidrug resistance protein MRP-7 in Caenorhabditis elegans (C. elegans) modulates whole animal and DA neuron sensitivity to MeHg. In this study we demonstrate that genetic knockdown of MRP-7 results in a 2-fold increase in Hg levels and a dramatic increase in stress response proteins associated with the endoplasmic reticulum, golgi apparatus, and mitochondria, as well as an increase in MeHg-associated animal death. Chronic exposure to low concentrations of MeHg induces MRP-7 gene expression, while exposures in MRP-7 genetic knockdown animals results in a loss of DA neuron integrity without affecting whole animal viability. Furthermore, transgenic animals expressing a fluorescent reporter behind the endogenous MRP-7 promoter indicate that the transporter is expressed in DA neurons. These studies show for the first time that a multidrug resistance protein is expressed in DA neurons, and its expression inhibits MeHg-associated DA neuron pathology.
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    The repair function of the multifunctional DNA repair/redox protein APE1 is neuroprotective after ionizing radiation
    (2011-09) Vasko, Michael R.; Guo, Chunlu; Thompson, Eric L.; Kelley, Mark R.
    Although exposure to ionizing radiation (IR) can produce significant neurotoxicity, the mechanisms mediating this toxicity remain to be determined. Previous studies using neurons isolated from the central nervous system show that IR produces reactive oxygen species and oxidative DNA damage in those cells. Because the base excision DNA repair pathway repairs single-base modifications caused by ROS, we asked whether manipulating this pathway by altering APE1 expression would affect radiation-induced neurotoxicity. In cultures of adult hippocampal and sensory neurons, IR produces DNA damage as measured by phosphorylation of histone H2A.X and results in dose-dependent cell death. In isolated sensory neurons, we demonstrate for the first time that radiation decreases the capsaicin-evoked release of the neuropeptide CGRP. Reducing APE1 expression in cultured cells augments IR-induced neurotoxicity, whereas overexpressing APE1 is neuroprotective. Using lentiviral constructs with a neuronal specific promoter that selectively expresses APE1s different functions in neurons, we show that selective expression of the DNA repair competent (redox inactive) APE1 constructs in sensory neurons resurrects cell survival and neuronal function, whereas use of DNA-repair deficient (redox active) constructs is not protective. Use of an APE1 redox-specific inhibitor, APX3330, also facilitates neuronal protection against IR-induced toxicity. These results demonstrate for the first time that the repair function of APE1 is required to protect both hippocampal and DRG neuronal cultures—specifically neuronal cells—from IR-induced damage, while the redox activity of APE1 does not appear to be involved.