Oxidizing Effects of Exogenous Stressors in Huntington’s Disease Knock-in Striatal Cells—Protective Effect of Cystamine and Creatine

Abstract

Huntington's disease (HD) is a polyglutamine-expansion disease associated to degeneration of striatal and cortical neurons. Previously, we showed that oxidative stress occurs in HD knock-in striatal cells, but little is known regarding cell antioxidant response against exogenous stimuli. Therefore, in the present study we analyzed cellular antioxidant profile following hydrogen peroxide (H2O2) and staurosporine (STS) exposure and tested the protective effect of cystamine and creatine in striatal cells expressing mutant huntingtin with 111 glutamines (STHdh (Q111/Q111); mutant cells) versus wild-type cells (STHdh (Q7/Q7)). Mutant cells displayed increased mitochondrial reactive oxygen species (ROS) and decreased NADPH oxidase and xanthine oxidase (XO) activities, reflecting lower superoxide cytosolic generation, along with increased superoxide dismutases (SODs) and components of glutathione redox cycle. Exposure to H2O2 and STS enhanced ROS in mutant cells and largely increased XO activity; STS further boosted the generation of mitochondrial ROS and caspase-3 activity. Both stimuli slightly increased SOD1 activity, without affecting SOD2 activity, and decreased glutathione reductase with a consequent rise in oxidized glutathione or glutathione disulfide in mutant cells, whereas H2O2 only increased glutathione peroxidase activity. Additionally, creatine and cystamine increased mutant cells viability and prevented ROS formation in HD cells subjected to H2O2 and STS. These results indicate that elevation of the antioxidant systems accompanies mitochondrial-driven ROS generation in mutant striatal cells and that exposure to noxious stimuli induces a higher susceptibility to oxidative stress by increasing XO activity and lowering the antioxidant response. Furthermore, creatine and cystamine are efficient in preventing H2O2- and STS-evoked ROS formation in HD striatal cells.

Overexpression of BDNF and Full-Length TrkB Receptor Ameliorate Striatal Neural Survival in Huntington's Disease

“…Caspase-3 activation and DNA fragmentation/condensation caused by a mild apoptotic stimulus with STS was previously observed by us in the HD mutant striatal cell line [48,49]. In the present work, cells exposed to STS or at basal conditions showed reduced caspase-3 activation in FL-TrkB-eGFP-overexpressing HD mutant cells exposed to rhBDNF, underlying an important role for functional TrkB receptors in HD striatal cells, particularly under a noxious stimulus.…”

Insulin and IGF-1 improve mitochondrial function in a PI-3K/Akt-dependent manner and reduce mitochondrial generation of reactive oxygen species in Huntington’s disease knock-in striatal cells

“…Mitochondria in HD striatal cells were recently described to be altered and more vulnerable to oxidative stress [33,49]. Indeed, elevated mitochondrial O 2 x-generation in HD knock-in striatal cells has been linked to mitochondrial dysfunction [90,91].…”

“…Because caspase-3 activation was previously observed in HD striatal cells [17,47,48], correlating with nuclear apoptotic features [49], we determined the effect of insulin and IGF-1 on caspase-3 activation and nuclear morphology, namely apoptotic and senescent nuclei, in mutant versus wild-type cells. Insulin (0.1 nM) significantly protected against caspase-3 activation in mutant cells ( Fig.…”

Oxidative Stress and Mitochondrial Dysfunction across Broad-Ranging Pathologies: Toward Mitochondria-Targeted Clinical Strategies

“…Moreover, CoQ10 and creatine exert additive neuroprotective effects in HD mice and rats. Evidence for MDF was provided by finding excess NADPH oxidase (NOX) activity in human HD brains, parallel with synaptosome fractions from cortex and striatum of HD (140Q/140Q) mice, suggesting that increased NOX2 activity at lipid rafts is an early and major source of OS and cell death in HD (140Q/140Q) neurons [89–92]. …”