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Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischaemia

ABSTRACT: The bioactive lipid intermediate palmitoyl CoA (PCoA) can inhibit mitochondrial ADP/ATP transport, though the physiological relevance of this regulation remains unclear. We questioned whether myocardial ischaemia was a pathological setting in which PCoA regulation of ADP/ATP transport would be beneficial. Secondly, whether the chronically elevated lipid content within the diabetic heart would make the mitochondria less sensitive to the inhibitory effects of PCoA, with detrimental consequences during ischaemia. Palmitoyl CoA acutely decreased ADP-stimulated state 3 respiration, increasing the Km for ADP 2-fold. The half maximal inhibitory concentration (IC50) of PCoA in control mitochondria was 22 µM. This inhibitory effect of PCoA on respiration was blunted in the diabetic mitochondria, with no significant difference in the Km in the presence of PCoA, and the IC50 increased to 32 µM PCoA. The competitive inhibition by PCoA was localised to the phosphorylation apparatus, particularly the ADP/ATP carrier (AAC). During ischaemia, the AAC imports ATP into the mitochondria, where it is hydrolysed by reversal of the ATP synthase, to regenerate the membrane potential. Addition of PCoA dose-dependently prevented this wasteful ATP hydrolysis for membrane repolarisation during ischaemia. However, this beneficial effect was blunted in the diabetic mitochondria. Finally, using 31P-magnetic resonance spectroscopy we demonstrated that diabetic hearts lose ATP more rapidly during ischaemia, with a 3-fold higher ATP decay rate compared with control hearts. In conclusion, PCoA plays a role in protecting mitochondrial energetics during ischaemia, by preventing wasteful ATP hydrolysis. However, this beneficial effect is blunted in diabetes, contributing to the impaired energy metabolism during myocardial ischaemia.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Rattus Norvegicus (rat)

TISSUE(S): Heart, Cardiac Muscle Tissue

DISEASE(S): Myocardial Ischemia

SUBMITTER: Roman Fischer

LAB HEAD: Roman Fischer

PROVIDER: PXD024500 | Pride | 2022-02-17

REPOSITORIES: Pride

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Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischemia.

Kerr M M Dennis K M J H KMJH Carr C A CA Fuller W W Berridge G G Rohling S S Aitken C L CL Lopez C C Fischer R R Miller J J JJ Clarke K K Tyler D J DJ Heather L C LC

FASEB journal : official publication of the Federation of American Societies for Experimental Biology 20210801 8

The bioactive lipid intermediate palmitoyl CoA (PCoA) can inhibit mitochondrial ADP/ATP transport, though the physiological relevance of this regulation remains unclear. We questioned whether myocardial ischemia provides a pathological setting in which PCoA regulation of ADP/ATP transport would be beneficial, and secondly, whether the chronically elevated lipid content within the diabetic heart could make mitochondria less sensitive to the effects of PCoA. PCoA acutely decreased ADP-stimulated s ...[more]

PMID: 34318967

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Project description:This model is from the article: Analyzing the functional properties of the creatine kinase system with multiscale 'sloppy' modeling. Hettling H, van Beek JH PLoS Comput Biol.2011 Aug;7(8):e1002130. PMEDID, Abstract: In this study the function of the two isoforms of creatine kinase (CK; EC 2.7.3.2) in myocardium is investigated. The 'phosphocreatine shuttle' hypothesis states that mitochondrial and cytosolic CK plays a pivotal role in the transport of high-energy phosphate (HEP) groups from mitochondria to myofibrils in contracting muscle. Temporal buffering of changes in ATP and ADP is another potential role of CK. With a mathematical model, we analyzed energy transport and damping of high peaks of ATP hydrolysis during the cardiac cycle. The analysis was based on multiscale data measured at the level of isolated enzymes, isolated mitochondria and on dynamic response times of oxidative phosphorylation measured at the whole heart level. Using 'sloppy modeling' ensemble simulations, we derived confidence intervals for predictions of the contributions by phosphocreatine (PCr) and ATP to the transfer of HEP from mitochondria to sites of ATP hydrolysis. Our calculations indicate that only 15±8% (mean±SD) of transcytosolic energy transport is carried by PCr, contradicting the PCr shuttle hypothesis. We also predicted temporal buffering capabilities of the CK isoforms protecting against high peaks of ATP hydrolysis (3750 µM*s(-1)) in myofibrils. CK inhibition by 98% in silico leads to an increase in amplitude of mitochondrial ATP synthesis pulsation from 215±23 to 566±31 µM*s(-1), while amplitudes of oscillations in cytosolic ADP concentration double from 77±11 to 146±1 µM. Our findings indicate that CK acts as a large bandwidth high-capacity temporal energy buffer maintaining cellular ATP homeostasis and reducing oscillations in mitochondrial metabolism. However, the contribution of CK to the transport of high-energy phosphate groups appears limited. Mitochondrial CK activity lowers cytosolic inorganic phosphate levels while cytosolic CK has the opposite effect. This model originates from BioModels Database: A Database of Annotated Published Models (http://www.ebi.ac.uk/biomodels/). It is copyright (c) 2005-2012 The BioModels.net Team. For more information see the terms of use. To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.

Dataset Information

Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischaemia

Publications

Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischemia.

Similar Datasets

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