Decreased cardiac mitochondrial NADP⁺-isocitrate dehydrogenase activity and expression: a marker of oxidative stress in hypertrophy development

Abstract

Mitochondrial dysfunction subsequent to increased oxidative stress and alterations in energy metabolism is considered to play a role in the development of cardiac hypertrophy and its progression to failure, although the sequence of events remains to be elucidated. This study aimed at characterizing the impact of hypertrophy development on the activity and expression of mitochondrial NADP+-isocitrate dehydrogenase (mNADP+-ICDH), a metabolic enzyme that controls redox and energy status. We expanded on our previous finding of its inactivation through posttranslational modification by the lipid peroxidation product 4-hydroxynonenal (HNE) in 7-wk-old spontaneously hypertensive rat (SHR) hearts before hypertrophy development (Benderdour et al. J Biol Chem 278: 45154-45159, 2003). In this study, we used 7-, 15-, and 30-wk-old SHR and Sprague-Dawley (SD) rats with abdominal aortic coarctation. Compared with age-matched control Wistar-Kyoto (WKY) rats, SHR hearts showed a significant 25% decrease of mNADP+-ICDH activity, which preceded in time 1) the decline in its protein and mRNA expression levels (between 10% and 35%) and 2) the increase in hypertrophy markers. The chronic and persistent loss of mNADP+-ICDH activity in SHR was associated with enhanced tissue accumulation of HNE-mNADP+-ICDH and total HNE-protein adducts at all ages and contrasted with the profile of changes in the activity of other mitochondrial enzymes involved in antioxidant or energy metabolism. Two-way ANOVA of the data also revealed a significant effect of age on most parameters measured in SHR and WKY hearts. The mNADP+-ICDH activity, protein, and mRNA expression were reduced between 25% and 35% in coarctated SD rats and were normalized by treatment of SHR or coarctated SD rats with renin-angiotensin system inhibitors, which prevented or attenuated hypertrophy. Altogether, our data show that cardiac mNADP+-ICDH activity and expression are differentially and sequentially affected in hypertrophy development and, to a lesser extent, with aging. Decreased cardiac mNADP+-ICDH activity, which is attributed at least in part to HNE adduct formation, appears to be a relevant early and persistent marker of mitochondrial oxidative stress-related alterations in hypertrophy development. Potentially, this could also contribute to the aetiology of cardiomyopathy.

Higher circulating 4-hydroxynonenal–protein thioether adducts correlate with more severe diastolic dysfunction in spontaneously hypertensive rats

“…11 Hence, it is unclear as to whether a 4-week treatment enabled probucol to reach all 4HNE producing sites, which based on our previous work appears to be intracellular, possibly in mitochondria. [5][6][7] Our correlation data support a potential role of 4HNE in the pathogenesis of diastolic dysfunction and in the regulation of heart rate in SHRs. We can only speculate on the underlying molecular mechanisms by which 4HNE could exert its effects.…”

“…The SHRs display enhanced oxidative stress in the vascular wall, 8 which responds to antioxidant treatment, 9 as well as decreased capacity to detoxify 4HNE. 10 Further to our finding of an accumulation of myocardial 4HNE-protein adducts in SHRs starting at 7 weeks, 7 we validated a gas chromatography-mass spectrometry (GC/MS) method to quantify HNE-protein thioether adducts in blood (4HNE-P) and found high circulating 4HNE-P in SHRs starting at 22 weeks of age. 5 Hence, in this study, we aimed at correlating circulating 4HNE-P with cardiac function in vivo and testing the impact of an antioxidant treatment with probucol.…”

“…We conducted a series of studies in spontaneously hypertensive rats (SHRs), [5][6][7] which provided the basis for exploring, in vivo, the potential link between 4HNE and cardiac function. The SHR is a well-established model of genetic hypertensive cardiomyopathy associated with insulin resistance.…”

Antenatal antioxidant prevents adult hypertension, vascular dysfunction, and microvascular rarefaction associated with in utero exposure to a low-protein diet

“…Because of this efficient metabolism, it is important to measure HNE, as well as DHN not to underestimate the true magnitude of lipid peroxidation under specific pathological conditions (75). Increased HNEmodified proteins have been reported in blood, heart, and brain in pathological conditions associated with oxidative stress (2,7,55,75,83). Interestingly, in the CTRL condition, the pattern of protein-adduct concentrations in the blood is the reverse to what is observed with kidney 8-isoPGF 2␣ levels with significantly higher levels in P7 vs. E21 and vs. adult animals (Fig.…”

Mitochondria: A mirror into cellular dysfunction in heart disease

“…Although there is no indication that the accumulation of HNE observed in I/R injury impacts the peroxidation status of cardiolipin in cardiomyopathy, HNE adduct formation does impact on the activity of NADP 1 -isocitrate dehydrogenase (NADP 1 -ICDH) through PTM [120], an event that precedes HCM. The addition of HNE to NADP 1 -ICDH via a cystine residue near the binding site of the substrate [120], results in a decrease in activity that also precedes the decrease in protein and gene expression [121], which occurs with disease. To date, there is very little proteomic data to support these functional and genomic investigations, which may be in part due to relative abundance issues associated with whole-cell and even intact mitochondrial approaches.…”