Diabetic cardiomyopathy and heart failure have been recognized as the leading causes of mortality among diabetics. Diabetic cardiomyopathy has been characterized primarily by the manifestation of left ventricular dysfunction that is independent of coronary artery disease and hypertension among the patients affected by diabetes mellitus. A complex array of contributing factors including the hypertrophy of left ventricle, alterations of metabolism, microvascular pathology, insulin resistance, fibrosis, apoptotic cell death, and oxidative stress have been implicated in the pathogenesis of diabetic cardiomyopathy. Nevertheless, the exact mechanisms underlying the pathogenesis of diabetic cardiomyopathy are yet to be established. The critical involvement of multifarious factors including the vascular endothelial dysfunction, microangiopathy, reactive oxygen species (ROS), oxidative stress, mitochondrial dysfunction has been identified in the mechanism of pathogenesis of diabetic cardiomyopathy. Although it is difficult to establish how each factor contributes to disease, the involvement of ROS and mitochondrial dysfunction are emerging as front-runners in the mechanism of pathogenesis of diabetic cardiomyopathy. This review highlights the role of vascular endothelial dysfunction, ROS, oxidative stress, and mitochondriopathy in the pathogenesis of diabetic cardiomyopathy. Furthermore, the review emphasizes that the puzzle has to be solved to firmly establish the mitochondrial and/or ROS mechanism(s) by identifying their most critical molecular players involved at both spatial and temporal levels in diabetic cardiomyopathy as targets for specific and effective pharmacological/therapeutic interventions.
In recent years, diabetes and its associated complications have come to represent a major public health concern. It is a complex disease characterized by multiple metabolic derangements and is known to impair cardiac function by disrupting the balance between pro-oxidants and antioxidants at the cellular level. The subsequent generation of reactive oxygen species (ROS) and accompanying oxidative stress are hallmarks of the molecular mechanisms responsible for cardiovascular disease. Among several oxidative stress-mediated mechanisms that have been proposed, ROS-mediated oxidative stress has received the most attention. ROS have been shown to interact with proteins, lipids, and DNA, causing damage to the cellular macromolecules and subsequently, deterioration of cellular function. Induction of thioredoxin-1 (Trx1) gene expression has been demonstrated to protect the diabetic myocardium from dysfunction by reducing oxidative stress and enhancing the expression of heme oxygenase-1 (HO-1) and vascular endothelial growth factor (VEGF). The failure of antioxidants to consistently demonstrate clinical benefit necessitates further investigation of the role of oxidative stress in diabetes-mediated cardiovascular disease.
Objective
Neuropilin-1 (NRP-1) is a multi-domain membrane receptor involved in angiogenesis and development of neuronal circuits, however, the role of NRP-1 in cardiovascular pathophysiology remains elusive.
Approach and Results
In this study, we first observed that deletion of NRP-1 induced peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) in cardiomyocytes (CMs) and vascular smooth muscle cells (VSMCs), which was accompanied by dysregulated cardiac mitochondrial accumulation and induction of cardiac hypertrophy- and stress-related markers. To investigate the role of NRP-1 in vivo, we generated mice lacking Nrp-1 in CMs and VSMCs (SM22-α-Nrp-1 KO), which exhibited decreased survival rates, developed cardiomyopathy and aggravated ischemia-induced heart failure. Mechanistically, we found that NRP-1 specifically controls PGC1α and PPARγ in CMs through crosstalk with Notch1 and Smad2 signaling pathways respectively. Moreover, SM22-α-Nrp-1 KO mice exhibited impaired physical activities and altered metabolite levels in serum, liver, and adipose tissues, as demonstrated by global metabolic profiling analysis.
Conclusions
Our findings provide new insights into the cardio-protective role of NRP-1 and its influence on global metabolism.
BackgroundThe present study demonstrates that the ubiquitin E3 ligase, Pellino‐1 (Peli1), is an important angiogenic molecule under the control of vascular endothelial growth factor (VEGF) receptor 2/Flk‐1. We have previously reported increased survivability of ischemic skin flap tissue by adenovirus carrying Peli1 (Ad‐Peli1) gene therapy in Flk‐1+/− mice.Methods and ResultsTwo separate experimental groups of mice were subjected to myocardial infarction (MI) followed by the immediate intramyocardial injection of adenovirus carrying LacZ (Ad‐LacZ) (1×109 pfu) or Ad‐Peli1 (1×109 pfu). Heart tissues were collected for analyses. Compared with wild‐type (WTMI) mice, analysis revealed decreased expressions of Peli1, phosphorylated (p‐)Flk‐1, p‐Akt, p‐eNOS, p‐MK2, p‐IκBα, and NF‐κB and decreased vessel densities in Flk‐1+/− mice subjected to MI (Flk‐1+/−
MI). Mice (CD1) treated with Ad‐Peli1 after the induction of MI showed increased β‐catenin translocation to the nucleus, connexin 43 expression, and phosphorylation of Akt, eNOS, MK2, and IκBα, that was followed by increased vessel densities compared with the Ad‐LacZ–treated group. Echocardiography conducted 30 days after surgery showed decreased function in the Flk1+/−
MI group compared with WTMI, which was restored by Ad‐Peli1 gene therapy. In addition, therapy with Ad‐Peli1 stimulated angiogenic and arteriogenic responses in both CD1 and Flk‐1+/− mice following MI. Ad‐Peli1 treatment attenuated cardiac fibrosis in Flk‐1+/−
MI mice. Similar positive results were observed in CD1 mice subjected to MI after Ad‐Peli1 therapy.ConclusionOur results show for the first time that Peli1 plays a unique role in salvaging impaired collateral blood vessel formation, diminishes fibrosis, and improves myocardial function, thereby offering clinical potential for therapies in humans to mend a damaged heart following MI.
BACKGROUND:
Our earlier studies showed that inhibiting prolyl-4-hydroxylase enzymes (PHD-1 and PHD-3) improves angiogenesis, heart function, and limb perfusion in mouse models via stabilizing hypoxia-inducible transcription factor-alpha (HIF-1α). The present study explored the effects of the prolyl-4-hydroxylase enzyme, PHD-2, on ischemic heart failure using cardiac-specific PHD-2 gene knockout (KO) mice (PHD2−/−).
STUDY DESIGN:
Adult wild-type (WT) and PHD2−/− mice, 8–12 weeks old, were subjected to myocardial infarction (MI) by irreversibly ligating the left anterior descending (LAD) coronary artery. All sham group mice underwent surgery without LAD ligation. Animals were divided into 4 groups: (1) wild-type sham (WTS); (2) wild-type myocardial infarction (WTMI); (3) PHD2KO sham (PHD2−/−S); (4) PHD2KO myocardial infarction (PHD2−/−MI). Left ventricular tissue samples collected at various time points after surgery were used for microRNA expression profiling, Western blotting, and immunohistochemical analysis.
RESULTS:
Volcano plot analysis revealed 19 differentially-expressed miRNAs in the PHD2−/−MI group compared with the WTMI group. Target analysis using Ingenuity Pathway Analysis showed several differentially regulated miRNAs targeting key signaling pathways such as Akt, VEGF, Ang-1, PTEN, apoptosis, and hypoxia pathways. Western blot analysis showed increased HIF-1α, VEGF, phospho-AKT, β-catenin expression and reduced Bax expression for the PHD2−/−MI group compared with the WTMI group. Echocardiographic analysis showed preserved heart functions, and picrosirius red staining revealed decreased fibrosis in PHD2−/−MI compared with the WTMI group.
CONCLUSIONS:
PHD2 inhibition showed preserved heart function, enhanced angiogenic factor expression, and decreased apoptotic markers after MI. Overall, cardiac PHD2 gene inhibition is a promising candidate for managing cardiovascular diseases.
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