Publications by authors named "Abhishek K Rauniyar"

6 Publications

  • Page 1 of 1

Trisomy 21 results in modest impacts on mitochondrial function and central carbon metabolism.

Free Radic Biol Med 2021 Jun 12;172:201-212. Epub 2021 Jun 12.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, USA; Linda Crnic Institute for Down Syndrome, School of Medicine, University of Colorado, Aurora, CO, USA. Electronic address:

Down syndrome (DS) is the most common genetic cause of intellectual disability. Mechanistically, oxidative stress and mitochondrial dysfunction are reported to be etiological factors for many of the DS-related comorbidities and have previously been reported in a number of in vitro and in vivo models of DS. The purpose of this study was to test for the presence of mitochondrial dysfunction in fibroblast cells obtained via skin biopsy from individuals with DS, and to assess the impact of trisomy 21 on central carbon metabolism. Using extracellular flux assays in matched dermal fibroblasts from euploid and DS individuals, we found that basal mitochondrial dysfunction is quite mild. Stressing the cells with a cocktail of mitochondrial stressors revealed a significant mitochondrial deficit in DS cells compared to euploid controls. Evaluation of extracellular acidification rate did not reveal a baseline abnormality in glycolysis; however, metabolomic assessments utilizing isotopically labeled glucose and glutamine revealed altered central carbon metabolism in DS cells. Specifically, we observed greater glucose dependency, uptake and flux into the oxidative phase of the pentose phosphate pathway in DS fibroblasts. Furthermore, using induced pluripotent stem cells (iPSC) we found that mitochondrial function in DS iPSCs was similar to the previously published studies employing fetal cells. Together, these data indicate that aberrant central carbon metabolism is a candidate mechanism for stress-related mitochondrial dysfunction in DS.
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http://dx.doi.org/10.1016/j.freeradbiomed.2021.06.003DOI Listing
June 2021

Cystathionine γ-lyase promotes estrogen-stimulated uterine artery blood flow via glutathione homeostasis.

Redox Biol 2021 04 8;40:101827. Epub 2020 Dec 8.

Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, 12700 E. 19th Avenue, Aurora, CO, 80045, USA; Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, 12700 E. 19th Avenue, Aurora, CO, 80045, USA. Electronic address:

During pregnancy, estrogen (E) stimulates uterine artery blood flow (UBF) by enhancing nitric oxide (NO)-dependent vasodilation. Cystathionine γ-lyase (CSE) promotes vascular NO signaling by producing hydrogen sulfide (HS) and by maintaining the ratio of reduced-to-oxidized intracellular glutathione (GSH/GSSG) through l-cysteine production. Because redox homeostasis can influence NO signaling, we hypothesized that CSE mediates E stimulation of UBF by modulating local intracellular cysteine metabolism and GSH/GSSG levels to promote redox homeostasis. Using non-pregnant ovariectomized WT and CSE-null (CSE KO) mice, we performed micro-ultrasound of mouse uterine and renal arteries to assess changes in blood flow upon exogenous E stimulation. We quantified serum and uterine artery NO metabolites (NO), serum amino acids, and uterine and renal artery GSH/GSSG. WT and CSE KO mice exhibited similar baseline uterine and renal blood flow. Unlike WT, CSE KO mice did not exhibit expected E stimulation of UBF. Renal blood flow was E-insensitive for both genotypes. While serum and uterine artery NO were similar between genotypes at baseline, E decreased NO in CSE KO serum. Cysteine was also lower in CSE KO serum, while citrulline and homocysteine levels were elevated. E and CSE deletion additively decreased GSH/GSSG in uterine arteries. In contrast, renal artery GSH/GSSG was insensitive to E or CSE deletion. Together, these findings suggest that CSE maintenance of uterine artery GSH/GSSG facilitates nitrergic signaling in uterine arteries and is required for normal E stimulation of UBF. These data have implications for pregnancy pathophysiology and the selective hormone responses of specific vascular beds.
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http://dx.doi.org/10.1016/j.redox.2020.101827DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7823052PMC
April 2021

Trisomy 21 impairs PGE2 production in dermal fibroblasts.

Prostaglandins Other Lipid Mediat 2021 Apr 5;153:106524. Epub 2021 Jan 5.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, USA; Linda Crnic Institute for Down Syndrome, Aurora, Colorado, USA. Electronic address:

The triplication of human chromosome 21 results in Down syndrome (DS), the most common genetic form of intellectual disability. This aneuploid condition also results in an enhanced risk of a spectrum of comorbid conditions, such as leukemia, early onset Alzheimer's disease, and diabetes. Individuals with DS also display an increased incidence of wound healing complications and resistance to solid tumor development. Due to this unique phenotype and the involvement of eicosanoids in key comorbidities like poor healing and tumor development, we hypothesized that cells from DS individuals would display altered eicosanoid production. Using age- and sex-matched dermal fibroblasts we interrogated this hypothesis. Briefly, assessment of over 90 metabolites derived from cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome p450 systems revealed a possible deficiency in the COX system. Basal gene expression and Western blotting experiments showed significantly decreased gene expression of COX1 and 2, and COX2 protein abundance in DS fibroblasts compared to euploid controls. Further, using two different stressors, scratch wound or LPS, we found that DS fibroblasts could not upregulate COX2 abundance and prostaglandin E2 production. Together, these findings show that dermal fibroblasts from DS individuals have a deficient COX2 response, which may contribute to wound healing complications and tumor resistance in DS.
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http://dx.doi.org/10.1016/j.prostaglandins.2020.106524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7965340PMC
April 2021

Maneb alters central carbon metabolism and thiol redox status in a toxicant model of Parkinson's disease.

Free Radic Biol Med 2021 01 3;162:65-76. Epub 2020 Dec 3.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO, 80045, USA. Electronic address:

The dithiocarbamate fungicide maneb (MB) has attracted interest due to increasing concern of the negative health effects of pesticides, as well as its association with Parkinson's disease (PD). Our laboratory has previously reported distinct phenotypic changes of neuroblastoma cells exposed to acute, sub-toxic levels of MB, including decreased mitochondrial respiration, altered lactate dynamics, and metabolic stress. In this study, we aimed to further define the specific molecular mechanisms of MB toxicity through the comparison of several thiol-containing compounds and their effects on cellular energy metabolism and thiol redox nodes. Extracellular flux analyses and stable isotope labeled tracer metabolomics were employed to evaluate alterations in energy metabolism of SK-N-AS human neuroblastoma cells after acute exposure of an array of compounds, including dithiocarbamates (maneb, nabam, zineb) and other thiol-containing small molecules (glutathione, N-acetylcysteine). These studies revealed MB and its methylated form (MeDTC) as unique toxicants with significant alterations to mitochondrial respiration, proliferation, and glycolysis. We observed MB to significantly impact cellular thiol redox status by oxidizing cellular glutathione and altering the thiol redox status of peroxiredoxin 3 (Prx3, mitochondrial) after acute exposure. Redox Western blotting revealed a MB-specific modification of cellular Prx3, strengthening the argument that MB can preferentially target mitochondrial enzymes containing reactive cysteine thiols. Further, stable isotope tracer metabolomics confirmed our energetics assessments, and demonstrated that MB exposure results in acute derangement of central carbon metabolism. Specifically, we observed shunting of cellular glucose into the pentose-phosphate pathway and reduction of TCA intermediates derived from glucose and glutamine. Also, we report novel lactate utilization for TCA enrichment and glutathione synthesis after MB exposure. In summary, our results further confirm that MB exerts its toxic effects via thiol modification, and significantly transforms central carbon metabolism.
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http://dx.doi.org/10.1016/j.freeradbiomed.2020.11.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889696PMC
January 2021

SNARE proteins rescue impaired autophagic flux in Down syndrome.

PLoS One 2019 12;14(11):e0223254. Epub 2019 Nov 12.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, United States of America.

Down syndrome (DS) is a chromosomal disorder caused by trisomy of chromosome 21 (Ts21). Unbalanced karyotypes can lead to dysfunction of the proteostasis network (PN) and disrupted proteostasis is mechanistically associated with multiple DS comorbidities. Autophagy is a critical component of the PN that has not previously been investigated in DS. Based on our previous observations of PN disruption in DS, we investigated possible dysfunction of the autophagic machinery in human DS fibroblasts and other DS cell models. Following induction of autophagy by serum starvation, DS fibroblasts displayed impaired autophagic flux indicated by autophagolysosome accumulation and elevated p62, NBR1, and LC3-II abundance, compared to age- and sex-matched, euploid (CTL) fibroblasts. While lysosomal physiology was unaffected in both groups after serum starvation, we observed decreased basal abundance of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein Receptor (SNARE) family members syntaxin 17 (STX17) and Vesicle Associated Membrane Protein 8 (VAMP8) indicating that decreased autophagic flux in DS is due at least in part to a possible impairment of autophagosome-lysosome fusion. This conclusion was further supported by the observation that over-expression of either STX17 or VAMP8 in DS fibroblasts restored autophagic degradation and reversed p62 accumulation. Collectively, our results indicate that impaired autophagic clearance is a characteristic of DS cells that can be reversed by enhancement of SNARE protein expression and provides further evidence that PN disruption represents a candidate mechanism for multiple aspects of pathogenesis in DS and a possible future target for therapeutic intervention.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223254PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850524PMC
March 2020

The burden of trisomy 21 disrupts the proteostasis network in Down syndrome.

PLoS One 2017 21;12(4):e0176307. Epub 2017 Apr 21.

Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, United States of America.

Down syndrome (DS) is a genetic disorder caused by trisomy of chromosome 21. Abnormalities in chromosome number have the potential to lead to disruption of the proteostasis network (PN) and accumulation of misfolded proteins. DS individuals suffer from several comorbidities, and we hypothesized that disruption of proteostasis could contribute to the observed pathology and decreased cell viability in DS. Our results confirm the presence of a disrupted PN in DS, as several of its elements, including the unfolded protein response, chaperone system, and proteasomal degradation exhibited significant alterations compared to euploid controls in both cell and mouse models. Additionally, when cell models were treated with compounds that promote disrupted proteostasis, we observed diminished levels of cell viability in DS compared to controls. Collectively our findings provide a cellular-level characterization of PN dysfunction in DS and an improved understanding of the potential pathogenic mechanisms contributing to disrupted cellular physiology in DS. Lastly, this study highlights the future potential of designing therapeutic strategies that mitigate protein quality control dysfunction.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0176307PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5400264PMC
September 2017
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