KIAA1199/CEMIP knockdown attenuates cardiac remodeling post myocardial infarction by activating TSP4 pathway in mice.

BACKGROUND: Excessive activation of cardiac fibroblasts (CFs) significantly contributes to adverse cardiac remodeling post-myocardial infarction (MI). CEMIP, initially recognized as an enzyme involved in hyaluronic acid (HA) degradation, has also been implicated in the activation of pulmonary fibroblasts. Nevertheless, the role and mechanism of CEMIP in adverse cardiac remodeling following MI remain largely unexplored. MATERIALS AND METHODS: RNA sequencing (RNA-seq) was performed on cardiac tissue harvested from the infarct/peri-infarct region of mice 28 days post-MI. RNA-seq was conducted on primary cardiac fibroblasts (CFs) transfected with adenovirus overexpressing CEMIP. Adeno-associated virus serotype 9 (AAV9) was engineered for in vivo CEMIP knockdown to elucidate its impact on cardiac remodeling. Immunoprecipitation coupled with mass spectrometry (IP-MS) and co-immunoprecipitation (co-IP) were employed to elucidate the mechanism by which CEMIP affected cardiac remodeling. KEY FINDINGS: RNA-seq of fibrotic heart tissue at day 28 post-MI revealed a significant upregulation of CEMIP. In vitro, CEMIP facilitated the activation of cardiac fibroblasts. In vivo, knockdown of CEMIP markedly reduced cardiac fibrosis and improved cardiac function post-MI. IP-MS and co-immunoprecipitation (co-IP) confirmed that CEMIP interacted with TSP4 through the G8 domain. Further experiments confirmed that CEMIP promoted TSP4 degradation in lysosomes in an ACTN4-dependent manner, thereby activating the FAK signaling pathway. SIGNIFICANCE: Our findings suggest that CEMIP significantly contributes to cardiac remodeling post-MI, which might be a novel approach for treating cardiac fibrosis following MI.

Protective role of cezanne in doxorubicin-induced cardiotoxicity by inhibiting autophagy, apoptosis and oxidative stress.

Doxorubicin (DOX) is frequently used in clinical practice for its broad-spectrum effects. However, its benefit is limited by a series of complications, including excessive apoptosis and autophagy of cardiomyocytes, overproduction of reactive oxygen species (ROS) and high level of oxidative stress. As a new protein, OTU domain-containing 7B (OTUD7B), also called Cezanne, has been reported to regulate many pathological processes. However, whether it plays a role in DOX-induced cardiotoxicity is still unclear. We discovered that the Cezanne level was significantly increased in DOX-treated neonatal rat cardiomyocytes (NRCMs) and C57BL/6 J mice hearts. In vitro, the knockdown of Cezanne with adenovirus in NRCMs significantly worsened DOX-induced apoptosis, autophagy and oxidative stress, while Cezanne overexpression showed opposite results. In vivo, the overexpression of Cezanne using cardiomyocyte-targeted adeno-associated virus 9 (AAV9) significantly reduced cardiomyocyte apoptosis, autophagy and oxidative stress level when C57BL/6 J mice were subjected to DOX. Mechanistically, the overexpression of Cezanne significantly reversed the in-activation of the PI3K/AKT/mTOR pathway induced by DOX, while the inhibitors of this pathway abolished the effect of Cezanne, suggesting that the PI3K/AKT/mTOR pathway plays a role in the protective function of Cezanne. These findings indicate that Cezanne could ameliorate DOX-induced cardiotoxicity by attenuating the apoptosis and autophagy of cardiomyocytes and decreasing the level of oxidative stress.

Platelet-rich plasma ameliorates lipopolysaccharide-induced cardiac injury by inflammation and ferroptosis regulation.

Sepsis-induced myocardial dysfunction (SIMD) is a fatal disease with no specific treatment worldwide to this day. As a biological product, platelet-rich plasma (PRP) has attracted much attention due to its diverse and potential biological effects. However, its role in lipopolysaccharide (LPS)-induced cardiac injury has not been fully investigated. This study aimed to explore the mechanism of PRP in SIMD. PRP (30 µL) was injected in situ into the heart, and LPS (10 mg/kg) was injected intraperitoneally into mice. Neonatal rat cardiomyocytes were treated with LPS (1 µg/ml) for 24 h. The results showed that, compared with the LPS group, PRP significantly decreased the levels of Lactate dehydrogenase (LDH) and Creatine Kinase MB (CK-MB), and improved cardiac function. In addition, PRP markedly decreased the Malonic dialdehyde (MDA) content, and increased the Superoxide dismutase (SOD) activity and Glutathione (GSH) level, demonstrating that PRP alleviated LPS-induced oxidative stress. The Western blot and qPCR results showed that LPS-induced ferroptosis and inflammation effects in vivo and in vitro were ameliorated after PRP treatment. Moreover, PRP can alleviate erastin-induced ferroptosis and improve cell viability. Mechanistically, p-AKT and p-mTOR expressions were down-regulated after treatment with LPS, while PRP pretreatment could reverse this effect. In summary, our study demonstrated that PRP could play a unique role in reducing LPS-induced cardiac injury through regulation of AKT/mTOR signaling pathways. These findings provide a new therapeutic direction for treating SIMD.

OTUD7B (Cezanne) ameliorates fibrosis after myocardial infarction via FAK-ERK/P38 MAPK signaling pathway.

Fibrosis is one of the crucial reasons for cardiac dysfunction after myocardial infarction (MI). Understanding the underlying molecular mechanism that causes fibrosis is crucial to developing effective therapy. Recently, OUT domain-containing 7B (OTUD7B), also called Cezanne, a multifunctional deubiquitylate, has been found to play various roles in cancer and vascular diseases and control many important signaling pathways, including inflammation, proliferation, and so on. However, whether OTUD7B plays a role in fibrosis caused by MI remains unclear. Our study aimed to explore the function of OTUD7B in cardiac fibrosis and investigate the underlying mechanism. We found that the expression of OTUD7B was downregulated in the MI rat model and cultured cardiac fibroblasts (CFs) in hypoxic conditions and after TGF-ß1 treatment. In vitro, silencing OTUD7B using small interfering RNA (siRNA) increased α-SMA (smooth muscle actin α) and collagen Ⅰ levels in CFs, whereas the overexpression of OTUD7B using adenovirus decreased their expression. Mechanistically, OTUD7B could regulate the phosphorylation of focal adhesion kinase (FAK), a non-receptor tyrosine kinase that has been proved to act as a potential mediator of fibrosis, and ERK/P38 MAPK was involved in this regulation process. In vitro, overexpression of OTUD7B downregulated the phosphorylation level of FAK and then inhibited ERK/P38 phosphorylation, thus leading to decreased α-SMA and collagen Ⅰ expressions, while OTUD7B knockdown showed an opposite result. These findings suggest that OTUD7B could become a potentially effective therapeutic strategy against fibrosis after MI.

RRM2 Alleviates Doxorubicin-Induced Cardiotoxicity through the AKT/mTOR Signaling Pathway.

Doxorubicin (DOX) is an effective chemotherapeutic agent that plays an unparalleled role in cancer treatment. However, its serious dose-dependent cardiotoxicity, which eventually contributes to irreversible heart failure, has greatly limited the widespread clinical application of DOX. A previous study has demonstrated that the ribonucleotide reductase M2 subunit (RRM2) exerts salutary effects on promoting proliferation and inhibiting apoptosis and autophagy. However, the specific function of RRM2 in DOX-induced cardiotoxicity is yet to be determined. This study aimed to elucidate the role and potential mechanism of RRM2 on DOX-induced cardiotoxicity by investigating neonatal primary cardiomyocytes and mice treated with DOX. Subsequently, the results indicated that RRM2 expression was significantly reduced in mice hearts and primary cardiomyocytes. Apoptosis and autophagy-related proteins, such as cleaved-Caspase3 (C-Caspase3), LC3B, and beclin1, were distinctly upregulated. Additionally, RRM2 deficiency led to increased autophagy and apoptosis in cells. RRM2 overexpression, on the contrary, alleviated DOX-induced cardiotoxicity in vivo and in vitro. Consistently, DIDOX, an inhibitor of RRM2, attenuated the protective effect of RRM2. Mechanistically, we found that AKT/mTOR inhibitors could reverse the function of RRM2 overexpression on DOX-induced autophagy and apoptosis, which means that RRM2 could have regulated DOX-induced cardiotoxicity through the AKT/mTOR signaling pathway. In conclusion, our experiment established that RRM2 could be a potential treatment in reversing DOX-induced cardiac dysfunction.

ADAMTS8 Promotes Cardiac Fibrosis Partly Through Activating EGFR Dependent Pathway.

Myocardial infarction or pressure overload leads to cardiac fibrosis, the leading cause of heart failure. ADAMTS8 (A disintegrin and metalloproteinase with thrombospondin motifs 8) has been reported to be involved in many fibrosis-related diseases. However, the specific role of ADAMTS8 in cardiac fibrosis caused by myocardial infarction or pressure overload is yet unclear. The present study aimed to explore the function of ADAMTS8 in cardiac fibrosis and its underlying mechanism. ADAMTS8 expression was significantly increased in patients with dilated cardiomyopathy; its expression myocardial infarction and TAC rat models was also increased, accompanied by increased expression of α-SMA and Collagen1. Adenovirus-mediated overexpression of ADAMTS8 through cardiac in situ injection aggravated cardiac fibrosis and impaired cardiac function in the myocardial infarction rat model. Furthermore, in vitro studies revealed that ADAMTS8 promoted the activation of cardiac fibroblasts; ADAMTS8 acted as a paracrine mediator allowing for cardiomyocytes and fibroblasts to communicate indirectly. Our findings showed that ADAMTS8 could damage the mitochondrial function of cardiac fibroblasts and then activate the PI3K-Akt pathway and MAPK pathways, promoting up-regulation of YAP expression, with EGFR upstream of this pathway. This study systematically revealed the pro-fibrosis effect of ADAMTS8 in cardiac fibrosis and explored its potential role as a therapeutic target for the treatment of cardiac fibrosis and heart failure.

MFGE8 is down-regulated in cardiac fibrosis and attenuates endothelial-mesenchymal transition through Smad2/3-Snail signalling pathway.

Endothelial-mesenchymal transition (EndMT) is a major source of transformed cardiac fibroblasts, which is reported to play a key role in cardiac fibrosis (CF), a pathogenesis of cardiovascular diseases such as heart failure, myocardial infarction and atrial fibrillation. Nonetheless, the specific mechanism underlying the progression of EndMT to CF is still largely unknown. In this study, we aimed to investigate the role of milk fat globule-EGF factor 8 (MFGE8), a kind of soluble glycoprotein, in TGF-ß1-induced EndMT. In animal experiments, the expression of MFGE8 was found down-regulated in the left ventricle and aorta of rats after transverse aortic constriction (TAC) compared with the sham group, especially in endothelial cells (ECs). In in vitro cultured ECs, silencing MFGE8 with small interfering RNA (siRNA) was found to promote the process of TGF-ß1-induced EndMT, whereas administration of recombinant human MFGE8 (rh-MFGE8) attenuated the process. Moreover, activated Smad2/3 signalling pathway after TGF-ß1 treatment and EndMT-related transcription factors, such as Snail, Twist and Slug, was potentiated by MFGE8 knock-down but inhibited by rh-MFGE8. In conclusion, our experiments indicate that MFGE8 might play a protective role in TGF-ß1-induced EndMT and might be a potential therapeutic target for cardiac fibrosis.