Elucidating the role of the A_2Aadenosine receptor in neurodegeneration using neurons derived from Huntington's disease iPSCs

Abstract

Huntington's disease (HD) is an autosomal-dominant degenerative disease caused by a cytosine-adenine-guanine trinucleotide expansion in the Huntingtin (htt) gene. The most vulnerable brain areas to mutant HTT-evoked toxicity are the striatum and cortex. In spite of the extensive efforts that have been devoted to the characterization of HD pathogenesis, no disease-modifying therapy for HD is currently available. The A2A adenosine receptor (A2AR) is widely distributed in the brain, with the highest level observed in the striatum. We previously reported that stimulation of the A2AR triggers an anti-apoptotic effect in a rat neuron-like cell line (PC12). Using a transgenic mouse model (R6/2) of HD, we demonstrated that A2AR-selective agonists effectively ameliorate several major symptoms of HD. In the present study, we show that human iPSCs can be successfully induced to differentiate into DARPP32-positive, GABAergic neurons which express the A2AR in a similar manner to striatal medium spiny neurons. When compared with those derived from control subjects (CON-iPSCs), these HD-iPSC-derived neurons exhibited a higher DNA damage response, based on the observed expression of γH2AX and elevated oxidative stress. This is a critical observation, because oxidative damage and abnormal DNA damage/repair have been reported in HD patients. Most importantly, stimulation of the A2AR using selective agonists reduced DNA damage and oxidative stress-induced apoptosis in HD-iPSC-derived neurons through a cAMP/PKA-dependent pathway. These findings support our hypothesis that human neurons derived from diseased iPSCs might serve as an important platform to investigate the beneficial effects and underlying mechanisms of A2AR drugs.

Direct Conversion of Human Fibroblasts into Neural Progenitors Using Transcription Factors Enriched in Human ESC-Derived Neural Progenitors

“…We previously reported that HD-iPSC-derived neurons are vulnerable to DNA damage, and that stimulation of A 2A R using selective agonists reduced DNA damage in HD-iPSC-derived neurons (Chiu et al., 2015). To identify whether the HD-iENPs and their neuronal derivatives recapitulate the above features of HD, we treated HD-iENPs and control-iENPs with a selective A 2A R agonist, CGS21680.…”

“…Several lines of evidence have indicated that stress factors can cause DNA damage and increase profound neuronal death in cells derived from HD patients (Jackson and Bartek, 2009). Also, it has been reported that A 2A R agonists are beneficial in HD transgenic animal models and an HD-iPSC-derived neuronal population (Chiu et al., 2015). In line with these observations, our results demonstrated that HD-iENPs and their neuronal derivatives were more susceptible to DNA damage than their counterparts derived from normal FBs.…”

Generation of Cholinergic and Dopaminergic Interneurons from Human Pluripotent Stem Cells as a Relevant Tool for In Vitro Modeling of Neurological Disorders Pathology and Therapy

“…For instance, the tumor necrosis factor-alpha (TNF α ) inhibitor XPro-1595 decreased cytokine induced apoptosis in neurons derived from iPSCs with 43 CAGs [89]. Adenosine receptor 2A agonists CGS-21680 and APEC reduced oxidative stress toxicity in the cells exposed to H 2 O 2 by decreased γ -H2A Histone Family Member X ( γ H2AX) induction and caspase 3 cleavage [90]. …”

iPSC-based drug screening for Huntington׳s disease

“…These examples represent endpoints suitable for HD screens in a high throughput format, which is especially valuable when screening thousands of potential therapeutic candidates. Other phenotypes that have been identified in MSNs derived from human HD-iPSCs are increased expression of γH2AX and elevated oxidative stress (67). In this study the A 2A R-selective agonists protected MSNs through the cAMP/PKA-dependent pathway (67).…”

“…Other phenotypes that have been identified in MSNs derived from human HD-iPSCs are increased expression of γH2AX and elevated oxidative stress (67). In this study the A 2A R-selective agonists protected MSNs through the cAMP/PKA-dependent pathway (67). Also observed in human HD NSCs is a deficit is manganese-dependent activation of p53 (68).…”