Abstract 11036: Enhanced Oxygen Utilization Efficiency with Concomitant Activation of the AMPK-TBC1D1 Signaling Nexus in Cyclophilin-D Conditional Knock-Out Mice

Circulation ◽  
2021 ◽  
Vol 144 (Suppl_2) ◽  
Author(s):  
Jeejabai Radhakrishnan ◽  
Alvin Baetiong ◽  
Raul J Gazmuri
Keyword(s):  
Adaptive Response ◽  
Glucose Transporter ◽  
Utilization Efficiency ◽  
Treadmill Running ◽  
Similar Response ◽  
Cyclophilin D ◽  
Knock Out ◽  
Session Interaction ◽  
Preferential Utilization ◽  
Β Tubulin

We have previously reported in HEK 293T cells and in constitutive cyclophilin-D (Cyp-D) knock-out (KO) mice that Cyp-D ablation downregulates oxygen consumption (VO 2 ) and triggers an adaptive response that manifests in higher exercise endurance with less VO 2 . This adaptive response involves a metabolic switch toward preferential utilization of glucose via the AMPK-TBC1D1 signaling nexus. We now investigated whether a similar response could be triggered in mice after acute ablation of Cyp-D using conditional KO (CKO) mice by subjecting them to treadmill exercise involving five running sessions. At their first treadmill running session, CKO mice and controls had comparable VO 2 (208.4±17.9 vs 209.1±16.8 ml/kg·min -1 ), VCO 2 (183.6±17.2 vs 184.8±16.9 ml/kg·min -1 ), and RER (0.88±0.043 vs 0.88±0.042). With subsequent sessions, CKO mice displayed more prominent reduction in VO 2 (genotype & session interaction p<0.001) with less prominent reduction in VCO 2 resulting in significantly increased RER (genotype & session interaction p=0.013). The increase in RER was consistent with preferential utilization of glucose as respiratory substrate (4.6±0.8 vs 4.0± 0.9 mg/min, p=0.003). CKO mice also performed a significantly higher treadmill work for given VO 2 expressed as a power/VO 2 ratio (7.4±0.2 x 10 -3 vs 6.7±0.2 10 -3 ratio, p=0.025). Analysis of CKO skeletal muscle tissue after completion of five treadmill running sessions showed enhanced AMPK activation (0.669±0.06 vs 0.409±0.11 pAMPK/β-tubulin ratio, p=0.005) and TBC1D1 inactivation (0.877±0.16 vs 0.565±0.09 pTBC1D1/β-tubulin ratio, p<0.05) accompanied by increased glucose transporter-4 levels consistent with activation of the AMPK-TBC1D1 signaling nexus enabling increased glucose utilization. Taken together, our study demonstrates that like constitutive Cyp-D ablation, acute Cyp-D ablation also induces a state of increased O 2 utilization efficiency, paving the way for exploring the use of a pharmacological approach to elicit the same response, which could be beneficial under O 2 limiting conditions.

scholarly journals Enhanced Oxygen Utilization Efficiency With Concomitant Activation of AMPK-TBC1D1 Signaling Nexus in Cyclophilin-D Conditional Knockout Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Jeejabai Radhakrishnan ◽  
Alvin Baetiong ◽  
Raúl J. Gazmuri
Keyword(s):  
Adaptive Response ◽  
Glucose Transporter ◽  
Conditional Knockout ◽  
Utilization Efficiency ◽  
Treadmill Running ◽  
Similar Response ◽  
Cyclophilin D ◽  
Session Interaction ◽  
Preferential Utilization ◽  
Β Tubulin

We have previously reported in HEK 293 T cells and in constitutive cyclophilin-D (Cyp-D) knockout (KO) mice that Cyp-D ablation downregulates oxygen consumption (VO2) and triggers an adaptive response that manifest in higher exercise endurance with less VO2. This adaptive response involves a metabolic switch toward preferential utilization of glucose via AMPK-TBC1D1 signaling nexus. We now investigated whether a similar response could be triggered in mice after acute ablation of Cyp-D using tamoxifen-induced ROSA26-Cre-mediated (i.e., conditional KO, CKO) by subjecting them to treadmill exercise involving five running sessions. At their first treadmill running session, CKO mice and controls had comparable VO2 (208.4 ± 17.9 vs. 209.1 ± 16.8 ml/kg min−1), VCO2 (183.6 ± 17.2 vs. 184.8 ± 16.9 ml/kg min−1), and RER (0.88 ± 0.043 vs. 0.88 ± 0.042). With subsequent sessions, CKO mice displayed more prominent reduction in VO2 (genotype &amp; session interaction p = 0.000) with less prominent reduction in VCO2 resulting in significantly increased RER (genotype and session interaction p = 0.013). The increase in RER was consistent with preferential utilization of glucose as respiratory substrate (4.6 ± 0.8 vs. 4.0 ± 0.9 mg/min, p = 0.003). CKO mice also performed a significantly higher treadmill work for given VO2 expressed as a power/VO2 ratio (7.4 ± 0.2 × 10−3 vs. 6.7 ± 0.2 10−3 ratio, p = 0.025). Analysis of CKO skeletal muscle tissue after completion of five treadmill running sessions showed enhanced AMPK activation (0.669 ± 0.06 vs. 0.409 ± 0.11 pAMPK/β-tubulin ratio, p = 0.005) and TBC1D1 inactivation (0.877 ± 0.16 vs. 0.565 ± 0.09 pTBC1D1/β-tubulin ratio, p &lt; 0.05) accompanied by increased glucose transporter-4 levels consistent with activation of the AMPK-TBC1D1 signaling nexus enabling increased glucose utilization. Taken together, our study demonstrates that like constitutive Cyp-D ablation, acute Cyp-D ablation also induces a state of increased O2 utilization efficiency, paving the way for exploring the use of pharmacological approach to elicit the same response, which could be beneficial under O2 limiting conditions.

Abstract 176: Genetic Ablation of Cyclophilin-D in Mice Increases Physical and Cognitive Performance During Hypoxia

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Jeejabai Radhakrishnan ◽  
Alvin Baetiong ◽  
Harrison Kaufman ◽  
Michelle Huynh ◽  
Angela Leschinsky ◽  
...  
Keyword(s):  
Cognitive Function ◽  
Cognitive Performance ◽  
Exercise Capacity ◽  
Motor Function ◽  
Elevated Plus Maze ◽  
Utilization Efficiency ◽  
Treadmill Running ◽  
Cyclophilin D ◽  
Hypoxic Conditions ◽  
Plus Maze

Introduction: We previously reported that silencing of the mitochondrial peptidyl-prolyl isomerase Cyclophilin-D (Cyp-D) in HEK 293T cells reduces oxygen consumption (VO 2 ). In vivo Cyp-D ablation using constitutive Cyp-D knockout (KO) mice also reduced VO 2 while paradoxically increased exercise endurance, thus demonstrating increased oxygen utilization efficiency. Therefore, we hypothesized that Cyp-D KO mice will display improved physical and cognitive performance during hypoxic conditions. Methods: Two groups of 9 mice each, age and gender-matched, representing wild-type (WT) and Cyp-D KO were subjected to treadmill running first under normobaric normoxic conditions (20.9% O 2 , simulating ground level O 2 levels), and the next day under normobaric hypoxic conditions (8% O 2 simulating 7,600 meters altitude O 2 levels). Total running time and distance, V max , and work performed were measured. A separate set of 9 mice each (Cyp-D KO and WT), were subjected to behavioral assessments; a pole test to assess motor function and an elevated plus-maze test to assess anxiety levels. The tests were conducted first under normoxia and then under hypoxia. Results: Cyp-D KO mice exposed to 8% O 2 displayed increased treadmill work (12±1 vs 8±1 Joules; p =0.02) demonstrating increased exercise capacity, shorter pole-climbing time (21±3 vs 37±4 sec; p =0.006) demonstrating increased agility and cognitive function, and increased elevated plus-maze open arm time (91±31 vs 23±12 sec; p =0.046) demonstrating anti-anxiety like behavior. Conclusions: Cyp-D KO mice demonstrated increased exercise capacity, improved motor function, decreased anxiety, and improved cognitive function under hypoxia. Thus, targeting Cyp-D and modulating its activity may impact several acute and chronic conditions in which oxygen availability is limited. The increased cognitive performance could be helpful when working at low environmental O 2 levels (e.g., high-altitude, underground caves, etc.).

scholarly journals Acute Low-Intensity Treadmill Running Upregulates the Expression of Intestinal Glucose Transporters via GLP-2 in Mice

Nutrients ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1735
Author(s):  
Kai Aoki ◽  
Takuji Suzuki ◽  
Fang Hui ◽  
Takuro Nakano ◽  
Koki Yanazawa ◽  
...  
Keyword(s):  
Small Intestine ◽  
Intestinal Tract ◽  
Glucose Transporter ◽  
Treadmill Running ◽  
Low Intensity ◽  
Glucose Transporter 2 ◽  
Intestinal Digestion ◽  
Glucagon Like Peptide ◽  
Low Intensity Exercise ◽  
Carbohydrate Digestion

The effects of exercise on nutrient digestion and absorption in the intestinal tract are not well understood. A few studies have reported that exercise training increases the expression of molecules involved in carbohydrate digestion and absorption. Exercise was also shown to increase the blood concentration of glucagon-like peptide-2 (GLP-2), which regulates carbohydrate digestion and absorption in the small intestine. Therefore, we investigated the effects of exercise on the expression of molecules involved in intestinal digestion and absorption, including GLP-2. Six-week-old male mice were divided into a sedentary (SED) and low-intensity exercise (LEx) group. LEx mice were required to run on a treadmill (12.5 m/min, 1 h), whereas SED mice rested. All mice were euthanized 1 h after exercise or rest, and plasma, jejunum, ileum, and colon samples were collected, followed by analysis via IHC, EIA, and immunoblotting. The levels of plasma GLP-2 and the jejunum expression of the GLP-2 receptor, sucrase-isomaltase (SI), and glucose transporter 2 (GLUT2) were higher in LEx mice. Thus, we showed that acute low-intensity exercise affects the expression of molecules involved in intestinal carbohydrate digestion and absorption via GLP-2. Our results suggest that exercise might be beneficial for small intestine function in individuals with intestinal frailty.

Abstract MP124: De-palmitoylation of Cysteine 202 of Cyclophilin-D by Calcium is Important for the Activation of the Permeability Transition Pore

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Georgios Amanakis ◽  
Junhui Sun ◽  
Maria Fergusson ◽  
Chengyu Liu ◽  
Jeff D Molkentin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Cyclophilin D ◽  
Perfused Heart ◽  
Knock Out

Cyclophilin-D (CypD) is a well-known regulator of the mitochondrial permeability transition pore (PTP), the main effector of cardiac ischemia/reperfusion (I/R) injury characterized by oxidative stress and calcium overload. However, the mechanism by which CypD activates PTP is poorly understood. Cysteine 202 of CypD (C202) is highly conserved across species and can undergo redox-sensitive post-translational modifications, such as S-nitrosylation and oxidation. To study the importance of C202, we developed a knock-in mouse model using CRISPR where CypD-C202 was mutated to a serine (C202S). Hearts from these mice are protected against I/R injury. We found C202 to be abundantly S-palmitoylated under baseline conditions while C202 was de-palmitoylated during ischemia in WT hearts. To further investigate the mechanism of de-palmitoylation during ischemia, we considered the increase of matrix calcium, oxidative stress and uncoupling of ATP synthesis from the electron transport chain. We tested the effects of these conditions on the palmitoylation of CypD in isolated cardiac mitochondria. The palmitoylation of CypD was assessed using a resin-assisted capture (Acyl-RAC). We report that oxidative stress (phenylarsenide) and uncoupling (CCCP) had no effect on CypD palmitoylation (p>0.05, n=3 and n=7 respectively). However, calcium overload led to de-palmitoylation of CypD to the level observed at the end ischemia (1±0.10 vs 0.63±0.09, p=0.012, n=9). To further test the hypothesis that calcium regulates S-palmitoylation of CypD we measured S-palmitoylation of CypD in non-perfused heart lysates from global germline mitochondrial calcium uniporter knock-out mice (MCU-KO), which have reduced mitochondrial calcium and we found an increase in S-palmitoylation of CypD (WT 1±0.04 vs MCU-KO 1.603±0.11, p<0.001, n=6). The data are consistent with the hypothesis that C202 is important for the CypD mediated activation of PTP. Ischemia leads to increased matrix calcium which in turn promotes the de-palmitoylation of CypD on C202. The now free C202 can further be oxidized during reperfusion leading to the activation of PTP. Thus, S-palmitoylation and oxidation of CypD-C202 possibly target CypD to the PTP, making them potent regulators of cardiac I/R injury.

scholarly journals Improved exercise capacity in cyclophilin‐D knockout mice associated with enhanced oxygen utilization efficiency and augmented glucose uptake via AMPK‐TBC1D1 signaling nexus

2019 ◽  
Vol 33 (10) ◽  
pp. 11443-11457 ◽  
Author(s):  
Jeejabai Radhakrishnan ◽  
Alvin Baetiong ◽  
Harrison Kaufman ◽  
Michelle Huynh ◽  
Angela Leschinsky ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Exercise Capacity ◽  
Knockout Mice ◽  
Utilization Efficiency ◽  
Cyclophilin D ◽  
Oxygen Utilization

scholarly journals The P66Shc/Mitochondrial Permeability Transition Pore Pathway Determines Neurodegeneration

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Costanza Savino ◽  
PierGiuseppe Pelicci ◽  
Marco Giorgio
Keyword(s):  
Oxidative Stress ◽  
Knockout Mice ◽  
Mitochondrial Permeability Transition ◽  
Neuronal Damage ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Swelling ◽  
Cyclophilin D ◽  
Knock Out ◽  
Mitochondrial Permeability

Mitochondrial-mediated oxidative stress and apoptosis play a crucial role in neurodegenerative disease and aging. Both mitochondrial permeability transition (PT) and swelling of mitochondria have been involved in neurodegeneration. Indeed, knockout mice for cyclophilin-D (Cyc-D), a key regulatory component of the PT pore (PTP) that triggers mitochondrial swelling, resulted to be protected in preclinical models of multiple sclerosis (MS), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). However, how neuronal stress is transduced into mitochondrial oxidative stress and swelling is unclear. Recently, the aging determinant p66Shc that generates H2O2reacting with cytochrome c and induces oxidation of PTP and mitochondrial swelling was found to be involved in MS and ALS. To investigate the role of p66Shc/PTP pathway in neurodegeneration, we performed experimental autoimmune encephalomyelitis (EAE) experiments in p66Shc knockout mice (p66Shc−/−), knock out mice for cyclophilin-D (Cyc-D−/−), and p66Shc Cyc-D double knock out (p66Shc/Cyc-D−/−) mice. Results confirm that deletion of p66Shc protects from EAE without affecting immune response, whereas it is not epistatic to the Cyc-D mutation. These findings demonstrate that p66Shc contributes to EAE induced neuronal damage most likely through the opening of PTP suggesting that p66Shc/PTP pathway transduces neurodegenerative stresses.

scholarly journals Autophagy mediates grain yield and nitrogen stress resistance by modulating nitrogen remobilization in rice

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0244996
Author(s):  
Xiaoxi Zhen ◽  
Naimeng Zheng ◽  
Jinlei Yu ◽  
Congyuan Bi ◽  
Fan Xu
Keyword(s):  
Grain Yield ◽  
N Uptake ◽  
Utilization Efficiency ◽  
Autophagic Flux ◽  
Knock Out ◽  
Elevated Expression ◽  
Transgenic Lines ◽  
N Remobilization ◽  
N Metabolism ◽  
N Harvest Index

Autophagy, a conserved cellular process in eukaryotes, has evolved to a sophisticated process to dispose of intracellular constituents and plays important roles in plant development, metabolism, and efficient nutrients remobilization under suboptimal nutrients conditions. Here, we show that OsATG8b, an AUTOPHAGY-RELATED8 (ATG8) gene in rice, was highly induced by nitrogen (N) starvation. Elevated expression of OsATG8b significantly increased ATG8 lipidation, autophagic flux, and grain yield in rice under both sufficient and deficient N conditions. Overexpressing of OsATG8b could greatly increase the activities of enzymes related to N metabolism. Intriguingly, the 15N-labeling assay further revealed that more N was remobilized to seeds in OsATG8b-overexpressing rice, which significantly increased the N remobilization efficiency (NRE), N harvest index, N utilization efficiency (NUE), and N uptake efficiency (NUpE). Conversely, the osatg8b knock-out mutants had the opposite results on these characters. The substantial transcriptional changes of the overexpressed transgenic lines indicated the presence of complex signaling to developmental, metabolic process, and hormone, etc. Excitingly, the transgenic rice under different backgrounds all similarly be boosted in yield and NUE with OsATG8b overexpression. This work provides an excellent candidate gene for improving N remobilization, utilization, and yield in crops simultaneously.

Regulation of hypoxia inducible factor/prolyl hydroxylase binding domain proteins 1 by PPARα and high salt diet

2018 ◽  
Vol 29 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Ezinne Ozurumba ◽  
Omana Mathew ◽  
Katsuri Ranganna ◽  
Myung Choi ◽  
Adebayo Oyekan
Keyword(s):  
Renal Function ◽  
Heme Oxygenase ◽  
Adaptive Response ◽  
Hypoxia Inducible Factor ◽  
Prolyl Hydroxylase ◽  
High Salt ◽  
Kidney Cortex ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Knock Out

Abstract Background: Hypoxia inducible factor (HIF)/prolyl hydroxylase domain (PHD)-containing proteins are involved in renal adaptive response to high salt (HS). Peroxisome proliferator activated receptor alpha (PPARα), a transcription factor involved in fatty acid oxidation is implicated in the regulation of renal function. As both HIF-1α/PHD and PPARα contribute to the adaptive changes to altered oxygen tension, this study tested the hypothesis that PHD-induced renal adaptive response to HS is PPARα-dependent. Methods: PPARα wild type (WT) and knock out (KO) mice were fed a low salt (LS) (0.03% NaCl) or a HS (8% NaCl) diet for 8 days and treated with hydralazine. PPARα and heme oxygenase (HO)-1 expression were evaluated in the kidney cortex and medulla. A 24-h urinary volume (UV), sodium excretion (UNaV), and nitrite excretion (UNOx V) were also determined. Results: PHD1 expression was greater in the medulla as compared to the cortex of PPARα WT mice (p<0.05) fed with a LS (0.03% NaCl) diet. The HS diet (8% NaCl) downregulated PHD1 expression in the medulla (p<0.05) but not the cortex of WT mice whereas expression was downregulated in the cortex (p<0.05) and medulla (p<0.05) of KO mice. These changes were accompanied by HS-induced diuresis (p<0.05) and natriuresis (p<0.05) that were greater in WT mice (p<0.05). Similarly, UNOx V, index of renal nitric oxide synthase (NOS) activity or availability and heme oxygenase (HO)-1 expression was greater in WT (p<0.05) but unchanged in KO mice on HS diet. Hydralazine, a PHD inhibitor, did not affect diuresis or natriuresis in LS diet-fed WT or KO mice but both were increased (p<0.05) in HS diet-fed WT mice. Hydralazine also increased UNOx V (p<0.05) with no change in diuresis, natriuresis, or HO-1 expression in KO mice on HS diet. Conclusions: These data suggest that HS-induced PPARα-mediated downregulation of PHD1 is a novel pathway for PHD/HIF-1α transcriptional regulation for adaptive responses to promote renal function via downstream signaling involving NOS and HO.

scholarly journals Cyclophilin D Knock-Out Mice Show Enhanced Resistance to Osteoporosis and to Metabolic Changes Observed in Aging Bone

PLoS ONE ◽  
2016 ◽  
Vol 11 (5) ◽  
pp. e0155709 ◽  
Author(s):  
Laura C. Shum ◽  
Noelle S White ◽  
Sergiy M. Nadtochiy ◽  
Karen L. de Mesy Bentley ◽  
Paul S Brookes ◽  
...  
Keyword(s):  
Metabolic Changes ◽  
Cyclophilin D ◽  
Knock Out ◽  
Enhanced Resistance ◽  
Knock Out Mice

scholarly journals Global Transcriptional Response of Aspergillus niger to Blocked Active Citrate Export through Deletion of the Exporter Gene

2021 ◽  
Vol 7 (6) ◽  
pp. 409
Author(s):  
Thanaporn Laothanachareon ◽  
Lyon Bruinsma ◽  
Bart Nijsse ◽  
Tom Schonewille ◽  
Maria Suarez-Diez ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Glucose Transporter ◽  
Carbon Sources ◽  
Transcriptional Response ◽  
Enrichment Analysis ◽  
Pathway Enrichment Analysis ◽  
Cultivation Conditions ◽  
Gene Encoding ◽  
Knock Out ◽  
Pathway Enrichment

Aspergillus niger is the major industrial citrate producer worldwide. Export as well as uptake of citric acid are believed to occur by active, proton-dependent, symport systems. Both are major bottlenecks for industrial citrate production. Therefore, we assessed the consequences of deleting the citT gene encoding the A. niger citrate exporter, effectively blocking active citrate export. We followed the consumption of glucose and citrate as carbon sources, monitored the secretion of organic acids and carried out a thorough transcriptome pathway enrichment analysis. Under controlled cultivation conditions that normally promote citrate secretion, the knock-out strain secreted negligible amounts of citrate. Blocking active citrate export in this way led to a reduced glucose uptake and a reduced expression of high-affinity glucose transporter genes, mstG and mstH. The glyoxylate shunt was strongly activated and an increased expression of the OAH gene was observed, resulting in a more than two-fold higher concentration of oxalate in the medium. Deletion of citT did not affect citrate uptake suggesting that citrate export and citrate uptake are uncoupled from the system.

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