Abstract 17405: Chronic Treatment of Ibrutinib Reduces PI3K Activation and Causes Increased Mitochondrial Oxidative Stress Leading to Heightened AF in Pitx2c +/- Mice

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Arvind Sridhar ◽  
ambili menon ◽  
Liang HONG ◽  
Brandon Chalazan ◽  
Meihong Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Kinase Inhibitor ◽  
Induced Pluripotent Stem Cell ◽  
Pi3k Pathway ◽  
Mitochondrial Fragmentation ◽  
Mitochondrial Oxidative Stress ◽  
Increased Risk ◽  
Pi3k Activation ◽  
Induced Pluripotent

Background: Ibrutinib, a Bruton’s tyrosine kinase inhibitor which is currently used as first line treatment to various B-cell malignancies is known to cause proarrhythmic effects in patients thus limiting its continual use. Ibrutinib treated patients have been shown to be at a 4-fold increased risk of developing atrial fibrillation (AF), but the underlying molecular mechanisms remain unclear. Studies have shown that Pitx2 , the nearest gene to the 4q25 locus has been implicated in AF pathology and thus can serve as an experimental model for clinical AF. Objective: The goal of this study is to assess the role of the late cardiac Na current (I Na,L ), PI3K activation, and oxidative stress in mediating the increased susceptibility to AF in Pitx2c +/- mice and atrial human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exposed to ibrutinib. Method: Pitx2c +/- mice were administered ibrutinib (30mg/kg/day IP) for 23 days after which their AF burden were assessed using transesophageal rapid pacing (TErP) along with their weight, BP, and plasma glucose. Atrial hiPSC-CMs were exposed to ibrutinib for 48 hrs. ELISA, IHC, Western blotting, cellular patch clamping and, qPCR studies were performed. Results: Pitx2c +/- mice were exposed to ibrutinib showed a graded increase in AF burden. ( Fig. 1A-C ). There was a decreased activation of the PI3K pathway and pAkt leading to overall decrease in SERCA2a expression ( Fig. 1D-F ). There was a significant increase in mitochondrial fragmentation and superoxide production in ibrutinib treated atrial hiPSC-CMs ( Fig G ) and the action potential duration at 90% repolarization and the I Na-L were markedly prolonged after ibrutinib exposure( Fig H ). Conclusion: We showed in Pitx2c +/- mice and atrial hiPSC-CMs that ibrutinib-mediated AF may in part be related to enhanced I Na-L , decreased activation of PI3K and SERCA2a and increased fibrosis leading to mitochondrial fragmentation and increased oxidative stress.

Abstract 246: Human Induced Pluripotent Stem Cells Reveal Mitophagy as an Essential Process Against Diabetic Cardiomyopathy

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Sang-Ging Ong ◽  
Won Hee Lee ◽  
Kazuki Kodo ◽  
Haodi Wu ◽  
Joseph C Wu
Keyword(s):  
Oxidative Stress ◽  
Diabetic Cardiomyopathy ◽  
Mitochondrial Fission ◽  
Induced Pluripotent Stem Cell ◽  
Mitochondrial Fragmentation ◽  
Normal Cells ◽  
Mitochondrial Pathology ◽  
Vitro Model ◽  
Induced Pluripotent

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.

scholarly journals Different molecular mechanisms involved in spontaneous and oxidative stress-induced mitochondrial fragmentation in tripeptidyl peptidase-1 (TPP-1)-deficient fibroblasts

2013 ◽  
Vol 33 (2) ◽  
Author(s):  
Guillaume Van Beersel ◽  
Eliane Tihon ◽  
Stéphane Demine ◽  
Isabelle Hamer ◽  
Michel Jadot ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Morphological Alteration ◽  
Neuronal Ceroid Lipofuscinoses ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Interacting Protein ◽  
Mitochondrial Oxidative Stress ◽  
Tripeptidyl Peptidase ◽  
And Oxidative Stress

NCLs (neuronal ceroid lipofuscinoses) form a group of eight inherited autosomal recessive diseases characterized by the intralysosomal accumulation of autofluorescent pigments, called ceroids. Recent data suggest that the pathogenesis of NCL is associated with the appearance of fragmented mitochondria with altered functions. However, even if an impairement in the autophagic pathway has often been evoked, the molecular mechanisms leading to mitochondrial fragmentation in response to a lysosomal dysfunction are still poorly understood. In this study, we show that fibroblasts that are deficient for the TPP-1 (tripeptidyl peptidase-1), a lysosomal hydrolase encoded by the gene mutated in the LINCL (late infantile NCL, CLN2 form) also exhibit a fragmented mitochondrial network. This morphological alteration is accompanied by an increase in the expression of the protein BNIP3 (Bcl2/adenovirus E1B 19 kDa interacting protein 3) as well as a decrease in the abundance of mitofusins 1 and 2, two proteins involved in mitochondrial fusion. Using RNAi (RNA interference) and quantitative analysis of the mitochondrial morphology, we show that the inhibition of BNIP3 expression does not result in an increase in the reticulation of the mitochondrial population in LINCL cells. However, this protein seems to play a key role in cell response to mitochondrial oxidative stress as it sensitizes mitochondria to antimycin A-induced fragmentation. To our knowledge, our results bring the first evidence of a mechanism that links TPP-1 deficiency and oxidative stress-induced changes in mitochondrial morphology.

Abstract MP58: Tissue And Sex Specific Effects Of Gstm1 Deletion In Mouse Models

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Yves Wang ◽  
Nhu Nguyen ◽  
Keith Nehrke ◽  
Paul S Brookes ◽  
Thu H Le
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Enzymes ◽  
Mouse Model ◽  
Molecular Mechanisms ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Antioxidant Properties ◽  
Iri Model ◽  
Increased Risk ◽  
Study Gene Expression

The glutathione S-transferase ( Gst ) gene family encodes antioxidant enzymes. In humans, a common null allele deletion variant of GST μ-1 ( GSTM1 ) is highly prevalent across populations and is associated with increased risk and progression of various diseases. Using a Gstm1 knockout (KO) mouse model, we previously showed that KO mice with angiotensin II-induced hypertension (HTN) have increased kidney injury compared to wild-type (WT) controls, mediated by elevated oxidative stress. In the same mouse model, we have recently reported that in a Langendorff-perfused cardiac ischemia-reperfusion injury (IRI) model, where damage is also mediated by oxidative stress, male KO hearts are protected while females are not. Here, we investigated the molecular mechanisms for this difference in male hearts. WT and KO mice of both sexes were studied at 12-20 weeks of age. Hearts were snap frozen at baseline and after 25 min of global ischemia, and kidneys were collected at baseline and 4 weeks following HTN induction. A panel of 18 Gst genes were probed by qPCR from baseline hearts and kidneys of both sexes. Global metabolites were assayed using Metabolon, Inc. from hearts of both sexes and kidneys of males, at both baseline and diseased states. Analysis by qPCR (n = 3/group) showed that male, but not female, KO hearts had upregulation of other Gst s. In contrast, no significant differences between were found in male kidneys. Metabolomics (n = 6/group) detected 695 metabolites in hearts and 926 in kidneys. There were increases in several metabolites in KO vs. WT hearts including those with antioxidant properties. Notably, increases in carnosine and anserine were observed in KO male hearts but not in female hearts, while that of other antioxidant-related metabolites were observed in hearts of both sexes, but not in kidneys. HTN induced significant increases in metabolites in KO vs. WT kidneys in the pathways related to and linking methionine, cysteine, and glutathione, which were not observed in hearts. In this study, gene expression and metabolites suggest that the mechanisms compensating for the loss of GSTM1 are both tissue and sex specific. The resulting differences in antioxidant enzymes and metabolites may explain the unexpected protection for male Gstm1 KO hearts in IRI.

scholarly journals High Content Screening and Proteomic Analysis Identify the Kinase Inhibitor BX795 as a Potent Neuroprotective Compound in a Patient-Derived Model of Parkinson’s Disease

2020 ◽  
Author(s):  
Nasia Antoniou ◽  
Kanella Prodromidou ◽  
Georgia Kouroupi ◽  
Martina Samiotaki ◽  
George Panayotou ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Protein Synthesis ◽  
High Throughput Screening ◽  
Kinase Inhibitor ◽  
Induced Pluripotent Stem Cell ◽  
Neuroprotective Effects ◽  
Mtorc1 Signaling ◽  
Neuroprotective Actions ◽  
Induced Pluripotent

AbstractCombining high throughput screening approaches with induced pluripotent stem cell (iPSC)-based disease models represents a promising unbiased strategy to identify therapies for neurodegenerative disorders. Here we applied high content imaging on iPSC-derived neurons from patients with familial Parkinson’s disease bearing the G209A (p.A53T) α-synuclein (αSyn) mutation and launched a screening campaign on a small kinase inhibitor library. We thus identified the multi-kinase inhibitor BX795 that at a single dose effectively restores disease-associated neurodegenerative phenotypes. Proteomics profiling mapped the molecular pathways underlying the neuroprotective effects of BX795 that comprised a cohort of 118 protein-mediators of the core biological processes of RNA metabolism, protein synthesis, modification and clearance, and stress response, all linked to the mTORC1 signaling hub. In agreement, expression of human p.A53T-αSyn in neuron-like cells affected key components of the mTORC1 pathway resulting in aberrant protein synthesis that was restored in the presence of BX795 with concurrent facilitation of autophagy. Taken together, we have developed an adaptable platform based on p.A53T iPSC-derived neurons for drug screening and identified a promising small molecule with potent neuroprotective actions as candidate therapeutic for PD and other protein conformational disorders.

scholarly journals N-Acetylcysteine prevents amyloid-β secretion in neurons derived from human pluripotent stem cells with trisomy 21

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiromitsu Toshikawa ◽  
Akihiro Ikenaka ◽  
Li Li ◽  
Yoko Nishinaka-Arai ◽  
Akira Niwa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stem Cells ◽  
Pluripotent Stem Cells ◽  
Therapeutic Option ◽  
Amyloid Β ◽  
Chromosome 21 ◽  
Extra Copy ◽  
Increased Risk ◽  
Induced Pluripotent

AbstractDown syndrome (DS) is caused by the trisomy of chromosome 21. Among the many disabilities found in individuals with DS is an increased risk of early-onset Alzheimer's disease (AD). Although higher oxidative stress and an upregulation of amyloid β (Aβ) peptides from an extra copy of the APP gene are attributed to the AD susceptibility, the relationship between the two factors is unclear. To address this issue, we established an in vitro cellular model using neurons differentiated from DS patient-derived induced pluripotent stem cells (iPSCs) and isogenic euploid iPSCs. Neurons differentiated from DS patient-derived iPSCs secreted more Aβ compared to those differentiated from the euploid iPSCs. Treatment of the neurons with an antioxidant, N-acetylcysteine, significantly suppressed the Aβ secretion. These findings suggest that oxidative stress has an important role in controlling the Aβ level in neurons differentiated from DS patient-derived iPSCs and that N-acetylcysteine can be a potential therapeutic option to ameliorate the Aβ secretion.

scholarly journals Role of sulfiredoxin as a peroxiredoxin-2 denitrosylase in human iPSC-derived dopaminergic neurons

2016 ◽  
Vol 113 (47) ◽  
pp. E7564-E7571 ◽  
Author(s):  
Carmen R. Sunico ◽  
Abdullah Sultan ◽  
Tomohiro Nakamura ◽  
Nima Dolatabadi ◽  
James Parker ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Redox Homeostasis ◽  
Induced Pluripotent Stem Cell ◽  
Neural Cells ◽  
Dependent Manner ◽  
Protective Function ◽  
Peroxiredoxin 2 ◽  
Induced Pluripotent

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.

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