Abstract MP252: Genetic Architecture Of Heart Mitochondrial Proteome Influencing Cardiac Hypertrophy

Our lab studies how natural genetic variations affect common diseases using a mouse population called hybrid mouse diversity panel (HMDP). In this study, we have explored the genetic regulation of mitochondrial pathways and their contribution to heart function using an integrative proteomics approach. We first performed a whole heart proteomic analysis in the HMDP (72 strains, n=2-3 mice) and surveyed mitochondrial localization using MitoCarta2.0. We retrieved 840 of these proteins (quantified in ≥50 strains) and performed high-resolution association mapping on their respective abundance levels to the HMDP genotypes. Our analyses identified three genetic loci, located on chromosome (chr) 7, chr13 and chr17, that control distinct classes of mitochondrial proteins as well as heart hypertrophy. Follow-up high resolution regional mapping identified NDUFS4, LRPPRC and COQ7 as the candidate genes for chr13, chr17 and chr7 loci, respectively. All three are associated with heart mass in two independent heart stress models, namely, isoproterenol (ISO)-induced heart failure and diet-induced obesity (DIO) models. Next, to identify the aspects of mitochondrial metabolism regulated by these loci, we constructed co-expression protein networks using weighted gene co-expression network analysis (WGCNA) and identified five modules. Eigengenes, representing the first principal component of two of these modules (Brown and Green), mapped to the same regions as the chr13 and chr17 loci, respectively. DAVID enrichment analyses revealed that the Brown module (72 proteins, 96% overlap with chr13) was highly enriched for complex-I proteins (35 proteins, P = 8.8E-74) and the Green module (44 proteins, 73% overlap with chr17) for mitochondrial ribosomal proteins (25 proteins, P = 1.3E-53). The proteins in the chr7 locus were found primarily in the Turquoise module (393 proteins, 81% overlap) but this module was not enriched for any single mitochondrial protein complex. In summary, we now report the identification of three genetic loci that control distinct classes of mitochondrial proteins as well as heart hypertrophy. Our results provide strong support for a role of the mitochondrial proteome in heart pathophysiology.

Diabetic Fetopathy As an Outcome of Manifest Diabetes Mellitus First Detected During Pregnancy

The article presents a clinical case of diabetic fetopathy in a newborn from a mother with diabetes mellitus, which manifested itself not only by phenotypic disorders, but also by morphological changes in the heart – hypertrophy of the left and right ventricles with obstruction of the outflow parts of the heart, the development of respiratory, heart failure, and neurological disorders. Disorder of carbohydrate metabolism in a patient with high risk factors for metabolic disorders, which was not detected in time, and the refusal of the necessary treatment led to the need to treat the newborn in the intensive care unit. The frequency of occurrence of diabetic fetopathy in different types of diabetes mellitus was shown on the basis of data from the Center for Endocrine Diseases of Pregnant Women on the basis of GKB No. 29

Increased Drp1 Acetylation by Lipid Overload Induces Cardiomyocyte Death and Heart Dysfunction

Rationale: Lipid overload-induced heart dysfunction is characterized by cardiomyocyte death, myocardial remodeling, and compromised contractility, but the impact of excessive lipid supply on cardiac function remains poorly understood. Objective: To investigate the regulation and function of the mitochondrial fission protein Drp1 (dynamin-related protein 1) in lipid overload-induced cardiomyocyte death and heart dysfunction. Methods and Results: Mice fed a high-fat diet (HFD) developed signs of obesity and type II diabetes mellitus, including hyperlipidemia, hyperglycemia, hyperinsulinemia, and hypertension. HFD for 18 weeks also induced heart hypertrophy, fibrosis, myocardial insulin resistance, and cardiomyocyte death. HFD stimulated mitochondrial fission in mouse hearts. Furthermore, HFD increased the protein level, phosphorylation (at the activating serine 616 sites), oligomerization, mitochondrial translocation, and GTPase activity of Drp1 in mouse hearts, indicating that Drp1 was activated. Monkeys fed a diet high in fat and cholesterol for 2.5 years also exhibited myocardial damage and Drp1 activation in the heart. Interestingly, HFD decreased nicotinamide adenine dinucleotide (oxidized) levels and increased Drp1 acetylation in the heart. In adult cardiomyocytes, palmitate increased Drp1 acetylation, phosphorylation, and protein levels, and these increases were abolished by restoration of the decreased nicotinamide adenine dinucleotide (oxidized) level. Proteomics analysis and in vitro screening revealed that Drp1 acetylation at lysine 642 (K642) was increased by HFD in mouse hearts and by palmitate incubation in cardiomyocytes. The nonacetylated Drp1 mutation (K642R) attenuated palmitate-induced Drp1 activation, its interaction with voltage-dependent anion channel 1, mitochondrial fission, contractile dysfunction, and cardiomyocyte death. Conclusions: These findings uncover a novel mechanism that contributes to lipid overload-induced heart hypertrophy and dysfunction. Excessive lipid supply created an intracellular environment that facilitated Drp1 acetylation, which, in turn, increased its activity and mitochondrial translocation, resulting in cardiomyocyte dysfunction and death. Thus, Drp1 may be a critical mediator of lipid overload-induced heart dysfunction as well as a potential target for therapy.

Does gender influence cardiovascular remodeling in C57BL/6J mice fed a high-fat, high-sucrose, high-salt diet?

Animal models are widely used to study the physiopathology of human diseases. However, the influence of gender on modern society diet style-induced cardiovascular disease was not exploited so far. Thus, this study investigated cardiovascular remodeling in C57BL/6J mice fed a diet rich in saturated fat, sucrose, and salt, evaluating gender effect on this process. Male and female C57BL/6J mice were fed AIN93M diet or a modified AIN93M rich in fat, sucrose, and salt (HFSS) for 12 weeks. Body mass, water and food intake and cardiovascular remodeling were assessed. The HFSS diet did not lead to body mass gain or glucose metabolism disturbance assessed by serum glucose, insulin, and oral glucose tolerance test. However, female mice on a HFSS diet had increased visceral and subcutaneous adiposity. Only male mice displayed heart hypertrophy. The left ventricle was not hypertrophied in male and female mice, but its lumen was dilated. Intramyocardial arteries and the thoracic aorta had intima-media thickening in male mice, but in the female, it was only noticed in the thoracic aorta. Finally, intramyocardial artery dilation was present in both genders, but not in the aorta. Changes in LV dimensions and the arterial remodeling were influenced by both gender and the HFSS diet. In conclusion, male and female C57BL/6J mice suffered cardiovascular remodeling after 12 weeks of high-fat, high-sucrose, high-salt feeding, although they did not develop obesity or diabetes. Sexual dimorphism occurred in response to diet for body adiposity, heart hypertrophy, and intramyocardial artery remodeling.

Cardiac hypertrophy and IGF-1 response to testosterone propionate treatment in trained male rats

ObjectiveSeveral studies have suggested that testosterone exerts a growth-promoting effect in the heart. Limited data are available regarding interactions between possible endocrine/paracrine effects in response to exercise training. Therefore, we examined supraphysiological testosterone-induced heart hypertrophy and cardiac insulin-like growth factor (IGF)-1 content in sedentary and exercise-trained rats.DesignMale Wistar rats (n=33) were randomly allocated to groups with a 6-week endurance training with or without testosterone, and sedentary animals with or without testosterone. The hormone (20 mg/250 g body weight was administrated once a week for six weeks. After six weeks the animals were anesthetized, euthanized and the heart was excised and weighed. The left ventricle was separated for biochemical analyses.ResultsTestosterone-treated animals showed significantly higher cardiac IGF-1 content compared to untreated control and trained groups (p=0.01). The administration of supraphysiological testosterone significantly increased the heart weight to body weight ratio (HW/BW, p<0.01). A significant positive correlation was seen between IGF-1 levels and the HW/BW ratio (p=0.002; r=0.50) and between serum total testosterone levels and HW/BW (p=0.000; r=0.79).ConclusionsThe results demonstrate that increased cardiac IGF-1 content in response to higher serum testosterone might be responsible for heart hypertrophy observed in both sedentary and endurance-trained animals.