scholarly journals Oxidative stress and loss of Fe-S proteins in Friedreich ataxia induced pluripotent stem cell-derived PSNs can be reversed by restoring FXN expression with a benzamide HDAC inhibitor

2017 ◽  
Author(s):  
Amelié Hu ◽  
Myriam Rai ◽  
Simona Donatello ◽  
Massimo Pandolfo

AbstractEpigenetic suppression of frataxin (FXN) expression caused by the presence of expanded GAA repeats at theFXNlocus is the key pathogenic event in Friedreich ataxia (FRDA), a recessive neurodegenerative and systemic disease. FXN is involved in iron-sulfur (Fe-S) cluster biogenesis in mitochondria, its deficiency causes multiple Fe-S protein deficiencies, mitochondrial dysfunction and oxidative stress. Primary sensory neurons (PSNs) in the dorsal root ganglia (DRGs) are the most vulnerable cells in FRDA, whose abnormal development and degeneration leads to the onset and early progression of ataxia. We generated PSNs from induced pluripotent stem cells (iPSCs) from FRDA patients and showed that they recapitulate the key pathogenic events in FRDA, including low FXN levels, loss of Fe-S proteins and impaired antioxidant responses. We also showed that FXN deficiency in these cells may be partially corrected by a pimelic benzamide histone deacetylase inhibitor, a class of potential therapeutics for FRDA. We generated and validated a cellular model of the most vulnerable neurons in FRDA, which can be used for further studies on pathogenesis and treatment approaches.

2019 ◽  
Author(s):  
Chiara Dionisi ◽  
Myriam Rai ◽  
Marine Chazalon ◽  
Serge N. Schiffmann ◽  
Massimo Pandolfo

AbstractHuman induced pluripotent stem cells (iPSCs) are used to generate models of human diseases that recapitulate the pathogenic process as it occurs in affected cells. Many differentiated cell types can currently be obtained from iPSCs, but no validated protocol is yet available to specifically generate primary proprioceptive neurons. Proprioceptors are affected in a number of genetic and acquired diseases, including Friedreich ataxia (FRDA).FRDA is a recessive neurodegenerative and systemic disease due to epigenetic suppression of frataxin (FXN) expression caused by the presence of expanded GAA repeats at the FXN locus. The most characteristic early neuropathologic finding in FRDA is the loss of large primary proprioceptive neurons in the dorsal root ganglia (DRGs), with associated loss of large myelinated fibers in the dorsal roots and in the posterior columns of the spinal cord. Both a developmental deficit and progressive neurodegeneration are thought to underlie the loss of proprioceptors in FRDA, though the relative contribution of these two components is unclear. The basis of the high specific vulnerability of proprioceptors in FRDA is also unknown. In order to address these open questions about FRDA pathogenesis and at the same time develop a cell model that can be applied to other conditions primarily affecting proprioceptors, we set up a protocol to differentiate iPSCs into primary proprioceptive neurons. We modified the dual-SMAD inhibition/WNT activation protocol, previously used to generate nociceptor-enriched cultures of primary sensory neurons from iPSCs, to favor instead the generation of proprioceptors. We succeeded in substantially enriching iPSC-derived primary sensory neuron cultures in proprioceptors, largely exceeding the proportion normally represented by these cells in dorsal root ganglia. We also showed that almost pure populations of proprioceptors can be purified from these cultures by fluorescence-activated cell sorting. Finally, we demonstrated that iPSCs from a FRDA patient can generate normal appearing proprioceptors but have subtle differentiation deficits and more limited survival.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Sang-Ging Ong ◽  
Won Hee Lee ◽  
Kazuki Kodo ◽  
Haodi Wu ◽  
Joseph C Wu

Diabetic cardiomyopathy is a common consequence of diabetes and associated with mitochondrial pathology. Using human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) as an in vitro model of diabetes, we sought to understand the role of mitophagy, a process that selectively degrades mitochondria through the autophagy-lysosome pathway as a crucial quality control pathway against diabetic cardiomyopathy. We first showed that iPSC-CMs exposed to a diabetic milieu demonstrated increased hypertrophy, impaired calcium signaling, and higher oxidative stress. Flow cytometry analysis of iPSC-CMs subjected to diabetic conditions revealed two distinct population of cells (normal and hypertrophied), suggesting a heterogeneous response to hyperglycemia. In these cells, hypertrophied iPSC-CMs were found to have reduced mitophagy compared to normal cells when exposed to hyperglycemia. In addition, we showed that mitochondrial fragmentation was also decreased in the hypertrophied iPSC-CMs compared to normal cells upon exposure to hyperglycemia, demonstrating a link between mitochondrial fragmentation and mitophagy. Surprisingly, pretreatment of iPSC-CMs with a non-selective antioxidant, N-(2-mercaptopropionyl)-glycine, not only failed to limit the deleterious effects of hyperglycemia, but actually led to increased hypertrophy and cell death. We found that mitophagy was significantly reduced in iPSC-CMs following antioxidant treatment, suggesting the need of mild oxidative stress as a trigger for mitophagy. Future studies are warranted to further investigate the association between oxidative stress, mitochondrial fragmentation, and mitochondrial fission as targets against diabetic cardiomyopathy.


2010 ◽  
Vol 7 (3) ◽  
pp. 703-713 ◽  
Author(s):  
Jun Liu ◽  
Paul J. Verma ◽  
Marguerite V. Evans-Galea ◽  
Martin B. Delatycki ◽  
Anna Michalska ◽  
...  

2016 ◽  
Vol 113 (47) ◽  
pp. E7564-E7571 ◽  
Author(s):  
Carmen R. Sunico ◽  
Abdullah Sultan ◽  
Tomohiro Nakamura ◽  
Nima Dolatabadi ◽  
James Parker ◽  
...  

Recent studies have pointed to protein S-nitrosylation as a critical regulator of cellular redox homeostasis. For example, S-nitrosylation of peroxiredoxin-2 (Prx2), a peroxidase widely expressed in mammalian neurons, inhibits both enzymatic activity and protective function against oxidative stress. Here, using in vitro and in vivo approaches, we identify a role and reaction mechanism of the reductase sulfiredoxin (Srxn1) as an enzyme that denitrosylates (thus removing -SNO) from Prx2 in an ATP-dependent manner. Accordingly, by decreasing S-nitrosylated Prx2 (SNO-Prx2), overexpression of Srxn1 protects dopaminergic neural cells and human-induced pluripotent stem cell (hiPSC)-derived neurons from NO-induced hypersensitivity to oxidative stress. The pathophysiological relevance of this observation is suggested by our finding that SNO-Prx2 is dramatically increased in murine and human Parkinson’s disease (PD) brains. Our findings therefore suggest that Srxn1 may represent a therapeutic target for neurodegenerative disorders such as PD that involve nitrosative/oxidative stress.


2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Ajit Magadum ◽  
Vandana Mallaredy ◽  
Grace Grace ◽  
Chunlin Wang ◽  
Rajika Roy ◽  
...  

Introduction: Cardiovascular diseases are the leading causes of death worldwide. After myocardial infarction (MI), there is a permanent loss of cardiomyocytes (CMs), and as the mammalian heart has limited regenerative capacity, it leads to Heart Failure. Recent studies from zebrafish and 1-day old mice showed that they could regenerate their heart through inducing existing CM proliferation. Attempts have been made to transiently reconstitute embryonic signaling in adult hearts, including overexpression of cell cycle activating genes with limited success. iPSC-derived extracellular vesicles (EV)/exosomes have been shown to improve cardiac function and some degree of CM renewal. However, the iPSC-EVs-mediated cardiac regeneration mechanism remains unclear and largely pertains to microRNAs and other RNAs, with a little elucidation of the role of iPSC-exosome proteins. Hypothesis: The myocardial delivery of iPSC-EV-specific protein improves cardiac function and remodeling post-MI by activating pro-proliferative and anti-oxidative stress molecular pathways. Methods and Results: Our preliminary studies showed that hiPSC-EVs induced the CM cell cycle in mice post-MI, and by employing a proteomic approach, we found a novel protein exclusively expressed in iPSC-EVs. The overexpression of hiPSC-EV enriched protein in the form of modRNA (modified mRNA) induced a robust CM cell cycle in rat neonatal CMs and in adult hearts post-MI. This increase in the CMs cell cycle by the modRNA was associated with reduced scar size, improved cardiac function (%EF 49.76 ± 5.8 vs. 27.47 ± 6.9 (control, Luc modRNA), respectively), and mice survival 28 days post-MI. Furthermore, using the siRNA and modRNA (inhibition and over-expression) approach, we found that the protein-induced Yap1-β-catenin molecular pathway stimulates CM proliferation. Furthermore, the overexpression protein post-MI inhibited the CM apoptosis (TUNEL + CMs, 1.3% ± 0.1 vs. 2.1% ± 0.11 (control)) by reducing oxidative stress and DNA damage response. Conclusion: The myocardial injection of iPSC-EV specific protein through a highly therapeutic modRNA tool improve cardiac function by inducing CMs proliferation, inhibiting oxidative stress, and reactivating cardiac regeneration post-injury.


2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Parvin Forghani ◽  
Aysha Rashid ◽  
Dong Li ◽  
Anant Mandawat ◽  
Chunhui XU

Cardiovascular toxicity post Carfilzomib (Cfz/Kyprolis) therapy has been identified in several clinical settings. A prevalent challenge in side effects of anti-cancer drugs is the translation of findings from preclinical research into clinical practice. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are being used as a physiological in vitro model to overcome some of these challenges. Here we used both 2D and 3D hiPSC-CMs to elucidate the underlying mechanism of post-Cfz cardiotoxicity. hiPSC-CMs were exposed to clinically relevant doses of Cfz based on C max for Cfz (5.88 μM). Data normalization against the control group demonstrates significant reduction in cell viability following two days of treatment with Cfz in 3 different cell lines (IMR-90, SCVI273 and 902). Increased Caspase3/7 activity post Cfz treatment paralleled with a substantial decrease in mitochondrial membrane potential and increase in oxidative stress following Cfz treatment. Also, significant decrease in oxygen consumption rate was observed after one-day exposure. In addition, we observed impaired Ca 2+ handling at the single cell level following Cfz treatment. Using video microscopy with motion vector analysis we also observed significant decrease in contractility of 3D hiPSC-CMs following Cfz treatment. Additionally, we observed disrupted expression of α-actinin, alterations in structural organization of sarcomeres, circularity and aspect ratio. Altogether, these results suggest that Cfz induced cardiotoxicity as indicated by cell viability, oxidative stress, mitochondrial and structural damages along with abnormal Ca 2+ handing and contractility dysfunction.


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