PARP1 Promotes Heart Regeneration and Cardiomyocyte Proliferation.

Myocardial infarction causes cardiomyocyte loss, and depleted cardiomyocyte proliferative capacity after birth impinges the heart repair process, eventually leading to heart failure. This study aims to investigate the role of Poly(ADP-Ribose) Polymerase 1 (PARP1) in the regulation of cardiomyocyte proliferation and heart regeneration. Our findings demonstrated that PARP1 knockout impaired cardiomyocyte proliferation, cardiac function, and scar formation, while PARP1 overexpression improved heart regeneration in apical resection-operated mice. Mechanistically, we found that PARP1 interacts with and poly(ADP-ribosyl)ates Heat Shock Protein 90 Alpha Family Class B Member 1 (HSP90AB1) and increases binding between HSP90AB1 and Cell Division Cycle 37 (CDC37) and cell cycle kinase activity, thus activating cardiomyocyte cell cycle. Our results reveal that PARP1 promotes heart regeneration and cardiomyocyte proliferation via poly(ADP-ribosyl)ation of HSP90AB1 activating the cardiomyocyte cell cycle, suggesting that PARP1 may be a potential therapeutic target in treating cardiac injury.

RNF207 exacerbates pathological cardiac hypertrophy via post-translational modification of TAB1.

AIMS: The heart undergoes pathological remodelling, featured by the hypertrophic growth of cardiomyocytes and increased cardiac fibrosis, under biomechanical stress such as haemodynamic overload. Ring Finger Protein 207 (RNF207) is an E3 ubiquitin ligase that is predominantly expressed in the heart, but its function remains elusive. In this study, we aimed to explore the role of RNF207 in the development of pathological cardiac hypertrophy and dysfunction. METHODS AND RESULTS: Transverse aortic constriction (TAC) surgery was performed on mice to induce cardiac hypertrophy. Cardiac function and remodelling were evaluated by echocardiography, histological assessment, and molecular analyses. Our data indicated that RNF207 overexpression (OE) exacerbated cardiac hypertrophy, fibrosis, and systolic dysfunction. In contrast, TAC-induced cardiac remodelling was profoundly blunted in RNF207 knockdown (KD) hearts. In line with the in vivo findings, RNF207 OE augmented, whereas RNF207 KD alleviated, phenylephrine-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we demonstrated that RNF207 elicited detrimental effects by promoting K63-linked ubiquitination of TAK1-binding protein 1 (TAB1), which triggered the autophosphorylation of transforming growth factor-ß activated kinase 1 (TAK1) and the activation of downstream p38 and c-Jun N-terminal kinase (JNK)1/2 signalling pathways. In the TAB1-KD cardiomyocytes, RNF207-OE-induced cell hypertrophy was significantly attenuated, indicating that RNF207-induced hypertrophy is, at least in part, TAB1-dependent. CONCLUSIONS: This study demonstrates that RNF207 exacerbates pressure overload-induced cardiac hypertrophy and dysfunction via post-translational modification of TAB1.

CD146 Associates with Gp130 to Control a Macrophage Pro-inflammatory Program That Regulates the Metabolic Response to Obesity.

The mechanism of obesity-related metabolic dysfunction involves the development of systemic inflammation, largely mediated by macrophages. Switching of M1-like adipose tissue macrophages (ATMs) to M2-like ATMs, a population of macrophages associated with weight loss and insulin sensitivity, is considered a viable therapeutic strategy for obesity-related metabolic syndrome. However, mechanisms for reestablishing the polarization of ATMs remain elusive. This study demonstrates that CD146+ ATMs accumulate in adipose tissue during diet-induced obesity and are associated with increased body weight, systemic inflammation, and obesity-induced insulin resistance. Inactivating the macrophage CD146 gene or antibody targeting of CD146 alleviates obesity-related chronic inflammation and metabolic dysfunction. Macrophage CD146 interacts with Glycoprotein 130 (Gp130), the common subunit of the receptor signaling complex for the interleukin-6 family of cytokines. CD146/Gp130 interaction promotes pro-inflammatory polarization of ATMs by activating JNK signaling and inhibiting the activation of STAT3, a transcription factor for M2-like polarization. Disruption of their interaction by anti-CD146 antibody or interleukin-6 steers ATMs toward anti-inflammatory polarization, thus attenuating obesity-induced chronic inflammation and metabolic dysfunction in mice. The results suggest that macrophage CD146 is an important determinant of pro-inflammatory polarization and plays a pivotal role in obesity-induced metabolic dysfunction. CD146 could constitute a novel therapeutic target for obesity complications.

Targeting the CD146/Galectin-9 axis protects the integrity of the blood-brain barrier in experimental cerebral malaria.

Cerebral malaria (CM) is a life-threatening diffuse encephalopathy caused by Plasmodium falciparum, in which the destruction of the blood-brain barrier (BBB) is the main cause of death. However, increasing evidence has shown that antimalarial drugs, the current treatment for CM, do little to protect against CM-induced BBB damage. Therefore, a means to alleviate BBB dysfunction would be a promising adjuvant therapy for CM. The adhesion molecule CD146 has been reported to be expressed in both endothelial cells and proinflammatory immune cells and mediates neuroinflammation. Here, we demonstrate that CD146 expressed on BBB endothelial cells but not immune cells is a novel therapeutic target in a mouse model of experimental cerebral malaria (eCM). Endothelial CD146 is upregulated during eCM development and facilitates the sequestration of infected red blood cells (RBCs) and/or proinflammatory lymphocytes in CNS blood vessels, thereby promoting the disruption of BBB integrity. Mechanistic studies showed that the interaction of CD146 and Galectin-9 contributes to the aggregation of infected RBCs and lymphocytes. Deletion of endothelial CD146 or treatment with the anti-CD146 antibody AA98 prevents severe signs of eCM, such as limb paralysis, brain vascular leakage, and death. In addition, AA98 combined with the antiparasitic drug artemether improved the cognition and memory of mice with eCM. Taken together, our findings suggest that endothelial CD146 is a novel and promising target in combination with antiparasitic drugs for future CM therapies.

Nanozyme chemiluminescence paper test for rapid and sensitive detection of SARS-CoV-2 antigen.

COVID-19 has evolved into a global pandemic. Early and rapid detection is crucial to control of the SARS-CoV-2 transmission. While representing the gold standard for early diagnosis, nucleic acid tests for SARS-CoV-2 are often complicated and time-consuming. Serological rapid antibody tests are characterized by high rates of false-negative diagnoses, especially during early infection. Here, we developed a novel nanozyme-based chemiluminescence paper assay for rapid and sensitive detection of SARS-CoV-2 spike antigen, which integrates nanozyme and enzymatic chemiluminescence immunoassay with the lateral flow strip. The core of our paper test is a robust Co-Fe@hemin-peroxidase nanozyme that catalyzes chemiluminescence comparable with natural peroxidase HRP and thus amplifies immune reaction signal. The detection limit for recombinant spike antigen of SARS-CoV-2 was 0.1 ng/mL, with a linear range of 0.2-100 ng/mL. Moreover, the sensitivity of test for pseudovirus could reach 360 TCID50/mL, which was comparable with ELISA method. The strip recognized SARS-CoV-2 antigen specifically, and there was no cross reaction with other coronaviruses or influenza A subtypes. This testing can be completed within 16 min, much shorter compared to the usual 1-2 h required for currently used nucleic acid tests. Furthermore, signal detection is feasible using the camera of a standard smartphone. Ingredients for nanozyme synthesis are simple and readily available, considerably lowering the overall cost. In conclusion, our paper test provides a high-sensitive point-of-care testing (POCT) approach for SARS-CoV-2 antigen detection, which should greatly facilitate early screening of SARS-CoV-2 infections, and considerably lower the financial burden on national healthcare resources.

25-Hydroxycholesterol protects against myocardial ischemia-reperfusion injury via inhibiting PARP activity.

Myocardial ischemia-reperfusion (IR) injury occurs when occlusive coronary artery restores blood supply after events such as myocardial infarction, stroke, cardiac arrest and resuscitation, and organ transplantation. However, the mechanisms involved are poorly understood, and effective pharmacological interventions are still lacking. A previous study demonstrated that 25-hydroxycholesterol (25-HC) contributed to lipid metabolism and cholesterol metabolism as an oxysterol molecule. We herein explored whether 25-hydroxycholesterol (25-HC) has cardioprotective properties against IR injury and explored its underlying mechanisms. 25-HC was administered before reperfusion procedure in IR injury model mice. We found that 25-HC significantly reduced the IR-induced infarct size and improved cardiac function, and this protective effect was associated with reduced phosphorylation of p38-MAPK and JNK1/2. Besides, 25-HC also inhibited the Bax/Bcl-2 ratio and the relative expression of cleaved caspase-3. Furthermore, 25-HC decreased the PARP activity, indicating that 25-HC ameliorates IR injury via the PARP pathway. The 25-HC group abolished cardioprotection in the presence of little PARP activity, suggesting that the PARP activity is essential for 25-HC to exert its effect during IR injury. Our primary study indicates that 25-HC ameliorated IR injury by inhibiting the PARP activity and decreasing myocardial apoptosis, which makes it a potential therapeutic drug in IR injury of the heart.

PRMT4 overexpression aggravates cardiac remodeling following myocardial infarction by promoting cardiomyocyte apoptosis.

Myocardial infarction due to coronary artery occlusion leads to adverse cardiac remodeling and heart failure. Apoptotic loss of cardiomyocytes near the ischemia area enlarges infarct area and promotes cardiac remodeling. Protein arginine methyltransferase 4 (PRMT4), a type I protein arginine methyltransferase, is involved in many cellular processes. Here we aimed to investigate the role of PRMT4 in cardiomyocyte apoptosis and myocardial infarction. We found that PRMT4 expression was markedly increased in ischemic heart and hypoxic cardiomyocytes. In vivo, cardiac-specific overexpression of PRMT4 in mice resulted in decreased survival rate, reduced left ventricular function, and aggravated cardiac remodeling following myocardial infarction. Mechanistically, PRMT4 overexpression promoted hypoxia-induced cardiomyocytes apoptosis, while its inhibition abolished these effects. Taken together, our work suggested an essential role of PRMT4 in myocardial infarction and cardiomyocyte apoptosis.

Redd1 protects against post­infarction cardiac dysfunction by targeting apoptosis and autophagy.

Post­infarction remodeling is accompanied and influenced by perturbations in the mammalian target of rapamycin (mTOR) signaling. Regulated in development and DNA damage response­1 (Redd1) has been reported to be involved in DNA repair and modulation of mTOR activity. However, little is known about the role of Redd1 in the heart. In the present study the potential contribution of Redd1 overexpression to the chronic phase of heart failure after myocardial infarction (MI) was explored and the mechanisms underlying Redd1 actions were determined. Redd1 was downregulated in the mouse heart subjected to MI surgery. To determine the role of Redd1 in the process of MI, adeno­associated virus 9 mediated overexpression of Redd1 was used to enhance Redd1 content in cardiomyocytes. Redd1 overexpression improved left ventricular dysfunction and reduced the expansion index. Additionally, Redd1 overexpression resulted in suppressed myocardial apoptosis and improved autophagy. Furthermore, the studies revealed that Redd1 overexpression could inhibit the phosphorylation of mTOR and its downstream effectors P70/S6 kinase and 4EBP1. In conclusion, this study demonstrated that Redd1 overexpression protects against the development and persistence of heart failure post MI by reducing apoptosis and enhancing autophagy via the mTOR signaling pathway. The present study clearly demonstrated that Redd1 is a therapeutic target in the development of heart failure after MI.

Poly(ADP-ribose) Polymerase-1 is required for hepatocyte proliferation and liver regeneration in mice.

Liver regeneration is an orchestrated cellular response and the mechanisms underlying it have been extensively studied using the partial hepatectomy (PHx) model. Poly(ADP-Ribose) Polymerase-1 (PARP1) is a common enzyme for post-translational modification of proteins. Here, we aimed to determine the role of PARP1 in liver regeneration. We found that PARP1 activity was strongly associated with hepatocyte proliferation after PHx. PARP1 knockout mice showed impaired liver recovery and suppressed hepatocyte proliferation after PHx. Mechanistically, PARP1 knockout repressed YAP activity and inhibited expression of cell cycle-associated proteins in liver tissues. Therefore, our findings highlight specialized roles for PARP1 in regulating hepatocytes proliferation and liver regeneration.

The role of CD27-CD70 signaling in myocardial infarction and cardiac remodeling.

BACKGROUND: CD4+ T cells are key players in regulating the inflammatory processes and physiological repair mechanisms engaged after acute myocardial infarction (AMI). Although signaling through the CD27-CD70 co-stimulatory pathway are known to be important in CD4+ T cell activation and proliferation in certain contexts, the role of the CD27-CD70 pathway in AMI remains unclear. METHODS AND RESULTS: A total of 43 control subjects, 42 unstable angina patients, and 90 AMI patients were enrolled in the present study. The serum levels of soluble CD27 (sCD27) in patients were measured, revealing a significant increase in serum sCD27 levels in AMI patients within 24 h of the cardiac event, after which they decreased. Correlation analyses revealed that serum sCD27 was positively correlated with cardiac troponin I (c-TnI) (r = 0.267, P = 0.011). When anti-CD70 antibody was used to block the CD27-CD70 pathway in MI model mice, we found that this treatment increased left ventricular end-diastolic dimension (LVEDD) (P < 0.01) and left ventricular end-systolic dimension (LVESD) (P < 0.01), and decreased ejection fraction (P < 0.01). Flow cytometric analysis revealed that the percentage of regulatory T cells was lower in blocking antibody-treated mice (P < 0.01), while neutrophils levels were higher (P < 0.01). The number of CD31-positive endothelial cells (P = 0.026) and α-smooth muscle actin-positive arterioles (P < 0.01) were significantly down-regulated in anti-CD70 treated-AMI mice. The formation of the extracellular matrix (ECM) was also impaired. CONCLUSION: Serum sCD27 may be a potential biomarker for AMI. Blockade of the CD27-CD70 pathway worsens cardiac dysfunction, aggravates left ventricular remodeling, and impairs scar healing after AMI, resulting in heart failure.

Blockage of K(Ca)3.1 and Kv1.3 channels of the B lymphocyte decreases the inflammatory monocyte chemotaxis.

OBJECTIVE: To investigate the effects of Ca(2+) activated potassium channel KCa3.1 and voltage-gated potassium channel Kv1.3 of B lymphocyte on inflammatory monocytes chemotaxis and the potential mechanisms. MATERIALS AND METHODS: Thanswell test was used to detect the inflammatory monocyte (Ly-6C(hi)) chemotaxis caused by the B lymphocyte. Enzyme-linked immunosorbent assay (ELISA) was applied to detecting the C-C motif ligand 7 (CCL7) in cultured media. Cell counting kit-8 (CCK) was used to detect the proliferation of B lymphocytes after activation and blockage of both KCa3.1 and Kv1.3 channels. Western blot was used to detect the expression of phosphorylated extracellular signal-regulated kinase (P-ERK) of the B lymphocytes. RESULTS: When activated, B lymphocytes significantly proliferated. After application of KCa3.1 channel-specific inhibitor TRAM-34 and potent Kv1.3 channel inhibitor ShK, both B lymphocytes proliferation and Ly-6C(hi) monocyte chemotaxis were significantly inhibited. The expression of chemotaxis related factor CCL7 decreased remarkably. CONCLUSION: The opening of KCa3.1 and Kv1.3 channels promote B lymphocyte activation, proliferation and Ly-6C(hi) monocyte chemotaxis. The increase of CCL7 secretion by B lymphocyte may explain the pro migration effects.

[Effect of Kv1.3 and KCa3.1 potassium ion channels on the proliferation and migration of monocytes/macrophages].

This study was aimed to investigate the effects of blockade of Ca(2+) activated channel KCa3.1 and voltage-gated potassium channel Kv1.3 of the monocytes/macrophages on inflammatory monocyte chemotaxis. Chemotaxis assay was used to test the inflammatory Ly-6C(hi) monocyte chemotaxis caused by the monocytes/macrophages. The proliferation of monocytes/macrophages was detected by cell counting kit-8 (CCK8). Enzyme-linked immunosorbent assay (ELISA) was applied to detect the C-C motif ligand 7 (CCL7) in cultured media. The results showed that the recruitment of Ly-6C(hi) monocyte induced by monocytes/macrophages was suppressed by the potent Kv1.3 blocker Stichodactyla helianthus neurotoxin (ShK) or the specific KCa3.1 inhibitor TRAM-34. Meanwhile, the proliferation of monocytes/macrophages was significantly inhibited by ShK. The response of Ly-6C(hi) monocyte pretreated with ShK or TRAM-34 to CCL2 was declined. These results suggest that KCa3.1 and Kv1.3 may play an important role in monocytes/macrophages' proliferation and migration.

Blockade of KCa3.1 Attenuates Left Ventricular Remodeling after Experimental Myocardial Infarction.

BACKGROUND/AIMS: After myocardial infarction (MI), cardiac fibrosis greatly contributes to left ventricular remodeling and heart failure. The intermediate-conductance calcium-activated potassium Channel (KCa3.1) has been recently proposed as an attractive target of fibrosis. The present study aimed to detect the effects of KCa3.1 blockade on ventricular remodeling following MI and its potential mechanisms. METHODS: Myocardial expression of KCa3.1 was initially measured in a mouse MI model by Western blot and real time-polymerase chain reaction. Then after treatment with TRAM-34, a highly selective KCa3.1 blocker, heart function and fibrosis were evaluated by echocardiography, histology and immunohistochemistry. Furthermore, the role of KCa3.1 in neonatal mouse cardiac fibroblasts (CFs) stimulated by angiotensin II (Ang II) was tested. RESULTS: Myocardium expressed high level of KCa3.1 after MI. Pharmacological blockade of KCa3.1 channel improved heart function and reduced ventricular dilation and fibrosis. Besides, a lower prevalence of myofibroblasts was found in TRAM-34 treatment group. In vitro studies KCa3.1 was up regulated in CFs induced by Ang II and suppressed by its blocker.KCa3.1 pharmacological blockade attenuated CFs proliferation, differentiation and profibrogenic genes expression and may regulating through AKT and ERK1/2 pathways. CONCLUSION: Blockade of KCa3.1 is able to attenuate ventricular remodeling after MI through inhibiting the pro-fibrotic effects of CFs.