KLF15 Regulates Oxidative Stress Response in Cardiomyocytes through NAD. Metabolites 2021;11:metabo11090620. [PMID: 34564436 PMCID: PMC8468172 DOI: 10.3390/metabo11090620]

Identification of circadian rhythm-related gene classification patterns and immune infiltration analysis in heart failure based on machine learning

Background

Circadian rhythms play a key role in the failing heart, but the exact molecular mechanisms linking changes in the expression of circadian rhythm-related genes to heart failure (HF) remain unclear.

Methods

By intersecting differentially expressed genes (DEGs) between normal and HF samples in the Gene Expression Omnibus (GEO) database with circadian rhythm-related genes (CRGs), differentially expressed circadian rhythm-related genes (DE-CRGs) were obtained. Machine learning algorithms were used to screen for feature genes, and diagnostic models were constructed based on these feature genes. Subsequently, consensus clustering algorithms and non-negative matrix factorization (NMF) algorithms were used for clustering analysis of HF samples. On this basis, immune infiltration analysis was used to score the immune infiltration status between HF and normal samples as well as among different subclusters. Gene Set Variation Analysis (GSVA) evaluated the biological functional differences among subclusters.

Results

13 CRGs showed differential expression between HF patients and normal samples. Nine feature genes were obtained through cross-referencing results from four distinct machine learning algorithms. Multivariate LASSO regression and external dataset validation were performed to select five key genes with diagnostic value, including NAMPT, SERPINA3, MAPK10, NPPA, and SLC2A1. Moreover, consensus clustering analysis could divide HF patients into two distinct clusters, which exhibited different biological functions and immune characteristics. Additionally, two subgroups were distinguished using the NMF algorithm based on circadian rhythm associated differentially expressed genes. Studies on immune infiltration showed marked variances in levels of immune infiltration between these subgroups. Subgroup A had higher immune scores and more widespread immune infiltration. Finally, the Weighted Gene Co-expression Network Analysis (WGCNA) method was utilized to discern the modules that had the closest association with the two observed subgroups, and hub genes were pinpointed via protein-protein interaction (PPI) networks. GRIN2A, DLG1, ERBB4, LRRC7, and NRG1 were circadian rhythm-related hub genes closely associated with HF.

Conclusion

This study provides valuable references for further elucidating the pathogenesis of HF and offers beneficial insights for targeting circadian rhythm mechanisms to regulate immune responses and energy metabolism in HF treatment. Five genes identified by us as diagnostic features could be potential targets for therapy for HF.

Targeting mitochondrial circadian rhythms: The potential intervention strategies of Traditional Chinese medicine for myocardial ischaemia‒reperfusion injury

Coronary artery disease has one of the highest mortality rates in the country, and methods such as thrombolysis and percutaneous coronary intervention (PCI) can effectively improve symptoms and reduce mortality, but most patients still experience symptoms such as chest pain after PCI, which seriously affects their quality of life and increases the incidence of adverse cardiovascular events (myocardial ischaemiareperfusion injury, MIRI). MIRI has been shown to be closely associated with circadian rhythm disorders and mitochondrial dysfunction. Mitochondria are a key component in the maintenance of normal cardiac function, and new research shows that mitochondria have circadian properties. Traditional Chinese medicine (TCM), as a traditional therapeutic approach characterised by a holistic concept and evidence-based treatment, has significant advantages in the treatment of MIRI, and there is an interaction between the yin-yang theory of TCM and the circadian rhythm of Western medicine at various levels. This paper reviews the clinical evidence for the treatment of MIRI in TCM, basic experimental studies on the alleviation of MIRI by TCM through the regulation of mitochondria, the important role of circadian rhythms in the pathophysiology of MIRI, and the potential mechanisms by which TCM regulates mitochondrial circadian rhythms to alleviate MIRI through the regulation of the biological clock transcription factor. It is hoped that this review will provide new insights into the clinical management, basic research and development of drugs to treat MIRI.

Krüppel-like Factor 15 Suppresses Ferroptosis by Activating an NRF2/GPX4 Signal to Protect against Folic Acid-Induced Acute Kidney Injury

Acute kidney injury (AKI) is a common and serious disease with high morbidity and mortality, and its pathophysiological mechanisms are not fully understood. Increasing evidence suggests an important role of ferroptosis in AKI. Krüppel-like factor 15 (KLF15) is a transcription factor involved in several metabolic diseases, but its role in AKI and ferroptosis remains unclear. In this study, we explored the potential role of KLF15 using a folic acid-induced AKI model. Our study showed that KLF15 expression was reduced in kidney tissues of AKI mice, and KLF15 knockout exacerbated folic acid-induced ferroptosis and kidney injury. In vitro studies revealed that the ferroptosis inducer erastin significantly suppressed KLF15 expression in human tubular epithelial cells. Notably, the overexpression of KLF15 attenuated ferroptosis, as evidenced by a decrease in the lipid peroxidation marker of malondialdehyde and the upregulation of glutathione peroxidase 4 (GPX4), while KLF15 knockdown with shRNA exerted the opposite effect. Mechanistically, KLF15 stabilized the protein of nuclear factor erythroid 2-related factor 2 (NRF2) and subsequently increased the GPX4 level. Collectively, KLF15 plays an important role in the modulation of ferroptosis in AKI and may be a potential therapeutic target for treating AKI.

Elabela blunts doxorubicin-induced oxidative stress and ferroptosis in rat aortic adventitial fibroblasts by activating the KLF15/GPX4 signaling

Doxorubicin (DOX) is a chemotherapeutic drug for a variety of malignancies, while its application is restricted by the cardiovascular toxic effects characterized by oxidative stress. Ferroptosis is a novel iron-dependent regulated cell death driven by lipid peroxidation. Our study aimed to investigate the role of Elabela (ELA) in DOX-induced oxidative stress and ferroptosis. In cultured rat aortic adventitial fibroblasts (AFs), stimulation with DOX dramatically induced cytotoxicity with reduced cell viability and migration ability, and enhanced lactate dehydrogenase (LDH) activity. Importantly, ELA and ferrostatin-1 (Fer-1) mitigated DOX-mediated augmentation of reactive oxygen species (ROS) in rat aortic AFs, accompanied by upregulated levels of Nrf2, SLC7A11, GPX4, and GSH. In addition, ELA reversed DOX-induced dysregulation of apoptosis- and inflammation-related factors including Bax, Bcl2, interleukin (IL)-1β, IL6, IL-10, and CXCL1. Intriguingly, knockdown of Krüppel-like factor 15 (KLF15) by siRNA abolished ELA-mediated alleviation of ROS production and inflammatory responses. More importanly, KLF15 siRNA impeded the beneficial roles of ELA in DOX-pretreated rat aortic AFs by suppressing the Nrf2/SLC7A11/GPX4 signaling. In conclusion, ELA prevents DOX-triggered promotion of cytotoxicity, and exerts anti-oxidative and anti-ferroptotic effects in rat aortic AFs via activation of the KLF15/GPX4 signaling, indicating a promising therapeutic value of ELA in antagonizing DOX-mediated cardiovascular abnormality and disorders.

Selenium Supplementation Protects Against Arsenic-Trioxide-Induced Cardiotoxicity Via Reducing Oxidative Stress and Inflammation Through Increasing NAD+ Pool

Arsenic is an environmental contaminant, and accumulating evidence has indicated that exposure to arsenic can cause various diseases, especially cardiotoxicity. Selenium (Se) exerts a vital role in the regulation of multiple physiological activities. Recently, several studies highlighted that Se treatment can effectively antagonize the toxic effects induced by arsenic. However, the exact underlying effect and mechanism of Se on Arsenic-induced cardiotoxicity has not been explored. In the current study, the arsenic trioxide (ATO)-triggered heart damage mice model was used to explore whether Se exerts protective roles in ATO-related cardiotoxicity and its potential mechanism. Our data showed that Se treatment significantly alleviated ATO-mediated cardiotoxicity evidenced by increased weight, decreased myocardial damage markers, and improved heart functions in mice. Furthermore, we demonstrated that Se remarkably inhibited ATO-mediated oxidative stress and inflammatory responses in heart tissues. Mechanistically, we showed that Se upregulated the levels of NAD⁺ in cardiomyocytes of the mice challenged by ATO, and this effect involved in the activation of the NAD⁺ biosynthesis through the salvage pathway. Collectively, our findings demonstrated that Se protected against ATO-mediated cardiotoxicity by antioxidant and anti-inflammatory effects via increasing the NAD⁺ pool in mice.