A CRM1 Inhibitor Alleviates Cardiac Hypertrophy and Increases the Nuclear Distribution of NT-PGC-1α in NRVMs

Vericiguat attenuates doxorubicin-induced cardiotoxicity through the PRKG1/PINK1/STING axis

Doxorubicin (DOX) is restricted due to its severe cardiotoxicity. There is still a lack of viable and effective drugs to prevent or treat DOX-induced cardiotoxicity(DIC). Vericiguat is widely used to treat heart failure with reduced ejection fraction. However, it is not clear whether vericiguat can improve DIC. In the present study, we constructed a DIC model using mice and neonatal rat cardiomyocytes and found that vericiguat ameliorated DOX-induced cardiac insufficiency in mice, restored DOX-induced mitochondrial dysfunction in neonatal rat cardiomyocytes, and inhibited the expression of inflammatory factors. Further studies showed that vericiguat improved mitochondrial dysfunction and reduced mtDNA leakage into the cytoplasm by up-regulating PRKG1, which activated PINK1 and then inhibited the STING/IRF3 pathway to alleviate DIC. These findings demonstrate for the first time that vericiguat has therapeutic potential for the treatment of DIC.

Metformin Collaborates with PINK1/Mfn2 Overexpression to Prevent Cardiac Injury by Improving Mitochondrial Function

Both mitochondrial quality control and energy metabolism are critical in maintaining the physiological function of cardiomyocytes. When damaged mitochondria fail to be repaired, cardiomyocytes initiate a process referred to as mitophagy to clear defective mitochondria, and studies have shown that PTEN-induced putative kinase 1 (PINK1) plays an important role in this process. In addition, previous studies indicated that peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) is a transcriptional coactivator that promotes mitochondrial energy metabolism, and mitofusin 2 (Mfn2) promotes mitochondrial fusion, which is beneficial for cardiomyocytes. Thus, an integration strategy involving mitochondrial biogenesis and mitophagy might contribute to improved cardiomyocyte function. We studied the function of PINK1 in mitophagy in isoproterenol (Iso)-induced cardiomyocyte injury and transverse aortic constriction (TAC)-induced myocardial hypertrophy. Adenovirus vectors were used to induce PINK1/Mfn2 protein overexpression. Cardiomyocytes treated with isoproterenol (Iso) expressed high levels of PINK1 and low levels of Mfn2, and the changes were time dependent. PINK1 overexpression promoted mitophagy, attenuated the Iso-induced reduction in MMP, and reduced ROS production and the apoptotic rate. Cardiac-specific overexpression of PINK1 improved cardiac function, attenuated pressure overload-induced cardiac hypertrophy and fibrosis, and facilitated myocardial mitophagy in TAC mice. Moreover, metformin treatment and PINK1/Mfn2 overexpression reduced mitochondrial dysfunction by inhibiting ROS generation leading to an increase in both ATP production and mitochondrial membrane potential in Iso-induced cardiomyocyte injury. Our findings indicate that a combination strategy may help ameliorate myocardial injury by improving mitochondrial quality.

Ganoderma lucidum polysaccharides attenuates pressure-overload-induced pathological cardiac hypertrophy

Pathological cardiac hypertrophy is an important risk factor for cardiovascular disease. However, drug therapies that can reverse the maladaptive process and restore heart function are limited. Ganoderma lucidum polysaccharides (GLPs) are one of the main active components of G. lucidum (Ganoderma lucidum), and they have various pharmacological effects. GLPs have been used as Chinese medicine prescriptions for clinical treatment. In this study, cardiac hypertrophy was induced by transverse aortic constriction (TAC) in mice. We found that GLPs ameliorate Ang II-induced cardiomyocyte hypertrophy in vitro and attenuate pressure overload-induced cardiac hypertrophy in vivo. Further research indicated that GLPs attenuated the mRNA levels of hypertrophic and fibrotic markers to inhibit cardiac hypertrophy through the PPARγ/PGC-1α pathway. Overall, these results indicate that GLPs inhibit cardiac hypertrophy through downregulating key genes for hypertrophy and fibrosis and attenuate pressure overload-induced pathological cardiac hypertrophy by activating PPARγ. This study provides important theoretical support for the potential of using GLPs to treat pathological myocardial hypertrophy and heart failure.

PGC-1α4 Interacts with REST to Upregulate Neuronal Genes and Augment Energy Consumption in Developing Cardiomyocytes

Transcriptional coactivator PGC-1α is a main regulator of cardiac energy metabolism. In addition to canonical PGC-1α1, other PGC-1α isoforms have been found to exert specific biological functions in a variety of tissues. We investigated the expression patterns and the biological effects of the non-canonical isoforms in the heart. We used RNA sequencing data to identify the expression patterns of PGC-1α isoforms in the heart. To evaluate the biological effects of the alternative isoform expression, we generated a transgenic mouse with cardiac-specific overexpression of PGC-1α4 and analysed the cardiac phenotype with a wide spectrum of physiological and biophysical tools. Our results show that non-canonical isoforms are expressed in the heart, and that the main variant PGC-1α4 is induced by β-adrenergic signalling in adult cardiomyocytes. Cardiomyocyte specific PGC-1α4 overexpression in mice relieves the RE1-Silencing Transcription factor (REST)-mediated suppression of neuronal genes during foetal heart development. The resulting de-repression of REST target genes induces a cardiac phenotype with increased cellular energy consumption, resulting in postnatal dilated cardiomyopathy. These results propose a new concept for actions of the PGC-1α protein family where activation of the Pgc-1α gene, through its isoforms, induces a phenotype with concurrent supply and demand for cellular energy. These data highlight the biological roles of the different PGC-1α isoforms, which should be considered when future therapies are developed.

Prostaglandin E1 attenuates AngII-induced cardiac hypertrophy via EP3 receptor activation and Netrin-1upregulation

AIMS

Pathological cardiac hypertrophy induced by activation of the renin-angiotensin-aldosterone system (RAAS) is one of the leading causes of heart failure. However, in current clinical practice, the strategy for targeting the RAAS is not sufficient to reverse hypertrophy. Here, we investigated the effect of prostaglandin E1 (PGE1) on angiotensin II (AngII)-induced cardiac hypertrophy and potential molecular mechanisms underlying the effect.

METHODS AND RESULTS

Adult male C57 mice were continuously infused with AngII or saline and treated daily with PGE1 or vehicle for two weeks. Neonatal rat cardiomyocytes were cultured to detect AngII-induced hypertrophic responses. We found that PGE1 ameliorated AngII-induced cardiac hypertrophy both in vivo and in vitro. The RNA sequencing (RNA-seq) and expression pattern analysis results suggest that Netrin-1 (Ntn1) is the specific target gene of PGE1. The protective effect of PGE1 was eliminated after knockdown of Ntn1. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the PGE1-mediated signaling pathway changes are associated with the mitogen-activated protein kinase (MAPK) pathway. PGE1 suppressed AngII-induced activation of the MAPK signaling pathway, and such an effect was attenuated by Ntn1 knockdown. Blockade of MAPK signaling rescued the phenotype of cardiomyocytes caused by Ntn1 knockdown, indicating that MAPK signaling may act as the downstream effector of Ntn1. Furthermore, inhibition of the E-prostanoid (EP) 3 receptor, as opposed to the EP1, EP2, or EP4 receptor, in cardiomyocytes reversed the effect of PGE1, and activation of EP3 by sulprostone, a specific agonist, mimicked the effect of PGE1.

CONCLUSION

In conclusion, PGE1 ameliorates AngII-induced cardiac hypertrophy through activation of the EP3 receptor and upregulation of Ntn1, which inhibits the downstream MAPK signaling pathway. Thus, targeting EP3, as well as the Ntn1-MAPK axis, may represent a novel approach for treating pathological cardiac hypertrophy.

Sirt1 improves heart failure through modulating the NF-κB p65/microRNA-155/BNDF signaling cascade

Heart failure (HF) affects over 26 million people worldwide, yet the pathologies of this complex syndrome have not been completely understood. Here, we investigated the involvement of deacetylase Sirtuin 1 (Sirt1) in HF and its downstream signaling pathways. A HF model was induced by the ligation of the left coronary artery in rats, where factors associated with left ventricular echocardiography, heart hemodynamics and ventricular mass indexes were recorded. Collagen volume fraction in heart tissues was determined by Masson's trichrome staining. Cell models of HF were also established (H₂O₂, 30 min) in cardiomyocytes harvested from suckling rats. HF rats presented with downregulated expressions of Sirt1, brain-derived neurotrophic factor (BDNF) and exhibited upregulated expressions of NF-κB p65 and miR-155. Repressed Sirt1 expression increased acetylation of NF-κB p65, resulting in the elevation of NF-κB p65 expression. NF-κB p65 silencing improved heart functions, decreased ventricular mass and reduced apoptosis in cardiomyocytes. MiR-155 inhibition upregulated its target gene BDNF, thereby reducing cardiomyocyte apoptosis. Sirt1 overexpression upregulated BDNF, improved heart function, and reduced apoptosis in cardiomyocytes. In conclusion, Sirt1 alleviates HF in rats through the NF-κB p65/miR-155/BDNF signaling cascade.

Citri reticulatae Pericarpium attenuates Ang II-induced pathological cardiac hypertrophy via upregulating peroxisome proliferator-activated receptors gamma

Background

Pathological cardiac hypertrophy is a major risk factor for cardiovascular diseases, including heart failure. However, limited pharmacological therapies are available for reversing the maladaptive process and restoring cardiac function. Citri reticulatae Pericarpium (CRP) has been used in traditional Chinese medicine prescriptions for clinical treatment. Previous studies have shown that CRP and its ingredients have beneficial effects on the cardiovascular system. However, whether CRP has a protective effect against pathological cardiac hypertrophy remains unknown.

Methods

Primary neonatal rat cardiomyocytes (NRCMs) were treated with angiotensin II (Ang II) to induce pathological hypertrophy in vitro. Immunofluorescent staining and quantitative real-time PCR (qRT-PCR) were used to determine the cell size and the expression of hypertrophic gene markers (Anp and Bnp), respectively. Male C57BL/6 mice were subjected to the investigation of cardiac hypertrophy induced by Ang II (2.5 mg/kg/d for 4 weeks). CRP (0.5 g/kg/d for 4 weeks) was administrated to treat mice with or without peroxisome proliferator-activated receptors gamma (PPARγ) inhibitor T0070907 (1 mg/kg/d for 4 weeks treatment) infused with Ang II. Cardiac hypertrophy (hematoxylin-eosin staining and qRT-PCR), fibrosis (Masson’s Trichrome staining, qRT-PCR, and western blot), and cardiac function (echocardiography) were examined in these mice. Western blot was used to determine the protein level of PPARγ and PGC-1α both in NRCMs and in mice.

Results

We found that CRP could prevent Ang II-induced pathological cardiac hypertrophy evidenced by improving cardiac function, decreasing hypertrophic growth and reducing cardiac fibrosis. Also, we demonstrated that PPARγ was upregulated by CRP both in NRCMs and in hearts. Moreover, PPARγ inhibitor could abolish the inhibitory effects of CRP on Ang II-induced pathological cardiac hypertrophy.

Conclusions

CRP attenuates Ang II-induced pathological cardiac hypertrophy by activating PPARγ.

Association of Urine Albumin/Creatinine Ratio below 30 mg/g and Left Ventricular Hypertrophy in Patients with Type 2 Diabetes

Several studies show that even a level of urine albumin/creatinine ratio (UACR) within the normal range (below 30 mg/g) increases the risk of cardiovascular diseases. We speculate that mildly increased UACR is related to left ventricular hypertrophy (LVH) in patients with type 2 diabetes mellitus (T2DM). In this retrospective study, 317 patients with diabetes with normal UACR, of whom 62 had LVH, were included. The associations between UACR and laboratory indicators, as well as LVH, were examined using multivariate linear regression and logistic regression, respectively. The diagnostic efficiency and the optimal cutoff point of UACR for LVH were evaluated using the area under the receiver operating characteristic curve (AUC) and Youden index. Our results showed that patients with LVH had significantly higher UACR than those without LVH (P < 0.001). The prevalence of LVH presented an upward trend with the elevation of UACR. UACR was independently and positively associated with hemoglobin A1c (P < 0.001). UACR can differentiate LVH (AUC = 0.682, 95% CI (0.602–0.760), P < 0.001). The optimal cutoff point determined with the Youden index was UACR = 10.2 mg/g. When categorized by this cutoff point, the odds ratio (OR) for LVH in patients in the higher UACR group (10.2–30 mg/g) was 3.104 (95% CI: 1.557–6.188, P=0.001) compared with patients in the lower UACR group (<10.2 mg/g). When UACR was analyzed as a continuous variable, every double of increased UACR, the OR for LVH was 1.511 (95% CI: 1.047–2.180, P=0.028). Overall, UACR below 30 mg/g is associated with LVH in patients with T2DM. The optimal cutoff value of UACR for identifying LVH in diabetes is 10 mg/g.