Autophagy and ubiquitin-dependent proteolysis processes in left ventricular mass loss in pulmonary arterial hypertension.

The goal of this study was to evaluate the intensity of autophagy and ubiquitin-dependent proteolysis processes occurring in myocardium of left ventricle (LV) in subsequent stages of pulmonary arterial hypertension (PAH) to determine mechanisms responsible for LV mass loss in a monocrotaline-induced PAH rat model. LV myocardium samples collected from 32 Wistar rats were analyzed in an early PAH group (n = 8), controls time-paired (n = 8), an end-stage PAH group (n = 8), and their controls (n = 8). Samples were subjected to histological analyses with immunofluorescence staining, autophagy assessment by western blotting, and evaluation of ubiquitin-dependent proteolysis in the LV by immunoprecipitation of ubiquitinated proteins. Echocardiographic, hemodynamic, and heart morphometric parameters were assessed regularly throughout the experiment. Considerable morphological and hemodynamic remodeling of the LV was observed over the course of PAH. The end-stage PAH was associated with significantly impaired LV systolic function and a decrease in LV mass. The LC3B-II expression in the LV was significantly higher in the end-stage PAH group compared to the early PAH group (p = 0.040). The measured LC3B-II/LC3B-I ratios in the end-stage PAH group were significantly elevated compared to the controls (p = 0.039). Immunofluorescence staining showed a significant increase in the abundance of LC3 puncta in the end-stage PAH group compared to the matched controls. There were no statistically significant differences in the levels of expression of all ubiquitinated proteins when comparing both PAH groups and matched controls. Autophagy may be considered as the mechanism behind the LV mass loss at the end stage of PAH.

Saponins of Panax japonicus ameliorates cardiac aging phenotype in aging rats by enhancing basal autophagy through AMPK/mTOR/ULK1 pathway.

Heart disease is a significant health concern for elderly individuals, with heart aging being the primary cause. Recent studies have shown that autophagy can play a protective role in preventing cardiac aging. Our previous research confirmed that Chikusetsu saponin IVa, a fundamental component of Saponins of Panax japonics (SPJ), can enhance basic autophagy levels in cardiomyocyte of isoproterenol induced cardiac fibrosis mice. However, it remains unclear whether SPJ possesses a protective effect on cardiac dysfunction during the natural aging process. Rats were randomly divided into four groups: adult control group (6 months old), aging group (24 months old), aging group treated with 10 mg/kg SPJ, and aging group treated with 30 mg/kg SPJ. The heart function, blood pressure, and heart mass index (HMI) were measured. Hematoxylin and eosin staining (H&E) and Wheat Germ Agglutinin (WGA) staining were used to observe the changes in morphology, while Masson staining was used to examine collagen deposition in the rat hearts and CD45 immunohistochemistry was conducted to examine the macrophage infiltration in heart tissues. TUNEL kit was used to detect apoptosis level of cardiomyocyte, and western blot was used to evaluate autophagy-related proteins as well as AMPK/mTOR/ULK1 pathway-related markers. SPJ treatment improved the cardiac function, reduced HMI, attenuated myocardial fiber disorder, inhibited inflammatory cell infiltration, and decreased collagen deposition and cardiomyocyte apoptosis in aging rats. Additionally, SPJ treatment decreased the expression of aging-related proteins and restored the expression of autophagy-related markers. SPJ activated autophagy through the activation of AMPK, which in turn increased the phosphorylation of ULK1(Ser555), while inhibited the phosphorylation of mTOR and ULK1(Ser757). Our study demonstrates that SPJ improves the cardiac function of aging rats by enhancing basal autophagy through the AMPK/mTOR/ULK1 pathway. These results offer a theoretical foundation and empirical evidence to support the clinical advancement of SPJ in enhancing age-related cardiac dysfunction.

Molecular mechanism of CAIF inhibiting myocardial infarction by sponging miR­488 and regulating AVEN expression.

In recent years, the global incidence and mortality of myocardial infarction (MI) has increased and become one of the important diseases threatening public health. Long non­coding (lnc)RNAs are a type of ncRNA that serve critical roles in the progression of various types of disease. The present study aimed to investigate the effect and mechanism of lncRNA cardiac autophagy inhibitory factor (CAIF) on cardiac ischemia/reperfusion (I/R) injury. CAIF was downregulated in the myocardium of I/R rats and cardiomyocytes treated with hydrogen peroxide (H2O2). Further experiments demonstrated that CAIF overexpression inhibited I/R­induced cardiac infarction and apoptosis in vivo. CAIF decreased H2O2­induced apoptosis and oxidative stress of cardiomyocytes. Mechanistically, CAIF sponged microRNA (miR)­488­5p; this interaction was confirmed by rescue experiments. Moreover, miR­488­5p targeted apoptosis and caspase activation inhibitor (AVEN) and inhibited its expression. In summary, the present data identified a novel CAIF/miR­488­5p/AVEN signaling axis as a key regulator of myocyte apoptosis, which may be a potential therapeutic target for the treatment of MI.

LncRNA cardiac autophagy inhibitory factor is downregulated in rheumatoid arthritis and suppresses the apoptosis of fibroblast-like synoviocytes by promoting the maturation of miRNA-20a.

Objectives: In this study, we aimed to investigate the effects of LncRNA cardiac autophagy inhibitory factor (CAIF) and miR-20a on the apoptosis of synovial cells in rheumatoid arthritis (RA) and the regulatory mechanism. Patients and methods: Between May 2018 and March 2020, a total of 62 RA patients (24 males, 38 females; mean age: 55.2±4.9 years; range, 42 to 68 years) and 62 controls (24 males, 38 females; mean age: 55.3±4.8 years; range, 41 to 68 years) were included in this study. Plasma samples were collected from all participants. The expression levels of CAIF, mature miR-20a, and miR-20a precursor in these plasma samples were determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Correlations were analyzed using linear regression analysis. Overexpression of CAIF was achieved in human fibroblast-like synoviocytes (HFLSs) and the expression levels of mature miR-20a and miR-20a precursor were determined using RT-qPCR. Cell apoptosis was analyzed by cell apoptosis assay. Results: The CAIF was downregulated in RA and positively correlated with the expression of mature miR-20a. In HFLSs, LPS treatment resulted in downregulation of both CAIF and miR-20a in a dose-dependent manner. In HFLSs, overexpression of CAIF did not affect the expression of miR-20a precursor, but upregulated the expression of mature miR-20a. Cell apoptosis analysis showed that overexpression of CAIF and miR-20a inhibited the apoptosis of HFLSs induced by LPS. The combination of overexpression of CAIF and miR-20a showed a stronger effect. Conclusion: The CAIF may suppress the apoptosis of HFLSs in RA by promoting the maturation of miR-20a.

Understanding the molecular mechanisms and role of autophagy in obesity.

Vital for growth, proliferation, subsistence, and thermogenesis, autophagy is the biological cascade, which confers defence against aging and various pathologies. Current research has demonstrated de novo activity of autophagy in stimulation of biological events. There exists a significant association between autophagy activation and obesity, encompassing expansion of adipocytes which facilitates ß cell activity. The main objective of the manuscript is to enumerate intrinsic role of autophagy in obesity and associated complications. The peer review articles published till date were searched using medical databases like PubMed and MEDLINE for research, primarily in English language. Obesity is characterized by adipocytic hypertrophy and hyperplasia, which leads to imbalance of lipid absorption, free fatty acid release, and mitochondrial activity. Detailed evaluation of obesity progression is necessary for its treatment and related comorbidities. Data collected in regard to etiological sustaining of obesity, has revealed hypothesized energy misbalance and neuro-humoral dysfunction, which is stimulated by autophagy. Autophagy regulates chief salvaging events for protein clustering, excessive triglycerides, and impaired mitochondria which is accompanied by oxidative and genotoxic stress in mammals. Autophagy is a homeostatic event, which regulates biological process by eliminating lethal cells and reprocessing physiological constituents, comprising of proteins and fat. Unquestionably, autophagy impairment is involved in metabolic syndromes, like obesity. According to an individual's metabolic outline, autophagy activation is essential for metabolism and activity of the adipose tissue and to retard metabolic syndrome i.e. obesity. The manuscript summarizes the perception of current knowledge on autophagy stimulation and its effect on the obesity.

Tsg101 positively regulates P62-Keap1-Nrf2 pathway to protect hearts against oxidative damage.

Currently, most antioxidants do not show any favorable clinical outcomes in reducing myocardial ischemia-reperfusion (I/R) injury, suggesting an urgent need for exploring a new regulator of redox homeostasis in I/R hearts. Here, using heart-specific transgenic (TG) and knockdown (KD) mouse models, tumor susceptibility gene 101 (Tsg101) is defined as a novel cardiac-protector against I/R-triggered oxidative stress. RNA sequencing and bioinformatics data surprisingly reveal that most upregulated genes in Tsg101-TG hearts are transcribed by Nrf2. Accordingly, pharmacological inhibition of Nrf2 offsets Tsg101-elicited cardio-protection. Mechanistically, Tsg101 interacts with SQSTM1/p62 through its PRR domain, and promotes p62 aggregation, leading to recruitment of Keap1 for degradation by autophagosomes and release of Nrf2 to the nucleus. Furthermore, knockout of p62 abrogates Tsg101-induced cardio-protective effects during I/R. Hence, our findings uncover a previously unrecognized role of Tsg101 in the regulation of p62/Keap1/Nrf2 signaling cascades and provide a new strategy for the treatment of ischemic heart disease.