Heat-Shock Protein 27 (HSPB1) Is Upregulated and Phosphorylated in Human Platelets during ST-Elevation Myocardial Infarction

Reticulon 3 deficiency ameliorates post-myocardial infarction heart failure by alleviating mitochondrial dysfunction and inflammation

Multiple molecular mechanisms are involved in the development of heart failure (HF) after myocardial infarction (MI). However, interventions targeting these pathological processes alone remain clinically ineffective. Therefore, it is essential to identify new therapeutic targets for alleviating cardiac dysfunction after MI. Here, gain- and loss-of-function approaches were used to investigate the role of reticulon 3 (RTN3) in HF after MI. We found that RTN3 was elevated in the myocardium of patients with HF and mice with MI. Cardiomyocyte-specific RTN3 overexpression decreased systolic function in mice under physiological conditions and exacerbated the development of HF induced by MI. Conversely, RTN3 knockout alleviated cardiac dysfunction after MI. Mechanistically, RTN3 bound and mediated heat shock protein beta-1 (HSPB1) translocation from the cytosol to the endoplasmic reticulum. The reduction of cytosolic HSPB1 was responsible for the elevation of TLR4, which impaired mitochondrial function and promoted inflammation through toll-like receptor 4 (TLR4)/peroxisome proliferator-activated receptor gamma coactivator-1 alpha(PGC-1α) and TLR4/Nuclear factor-kappa B(NFκB) pathways, respectively. Furthermore, the HSPB1 inhibitor reversed the protective effect of RTN3 knockout on MI. Additionally, elevated plasma RTN3 level is associated with decreased cardiac function in patients with acute MI. This study identified RTN3 as a critical driver of HF after MI and suggests targeting RTN3 as a promising therapeutic strategy for MI and related cardiovascular diseases.

Proteomic analysis of plasma proteins from patients with cardiac rupture after acute myocardial infarction using TMT-based quantitative proteomics approach

BACKGROUND

Cardiac rupture (CR) is a rare but catastrophic mechanical complication of acute myocardial infarction (AMI) that seriously threatens human health. However, the reliable biomarkers for clinical diagnosis and the underlying signaling pathways insights of CR has yet to be elucidated.

METHODS

In the present study, a quantitative approach with tandem mass tag (TMT) labeling and liquid chromatography-tandem mass spectrometry was used to characterize the differential protein expression profiles of patients with CR. Plasma samples were collected from patients with CR (n = 37), patients with AMI (n = 47), and healthy controls (n = 47). Candidate proteins were selected for validation by multiple reaction monitoring (MRM) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

In total, 1208 proteins were quantified and 958 differentially expressed proteins (DEPs) were identified. The difference in the expression levels of the DEPs was more noticeable between the CR and Con groups than between the AMI and Con groups. Bioinformatics analysis showed most of the DEPs to be involved in numerous crucial biological processes and signaling pathways, such as RNA transport, ribosome, proteasome, and protein processing in the endoplasmic reticulum, as well as necroptosis and leukocyte transendothelial migration, which might play essential roles in the complex pathological processes associated with CR. MRM analysis confirmed the accuracy of the proteomic analysis results. Four proteins i.e., C-reactive protein (CRP), heat shock protein beta-1 (HSPB1), vinculin (VINC) and growth/differentiation factor 15 (GDF15), were further validated via ELISA. By receiver operating characteristic (ROC) analysis, combinations of these four proteins distinguished CR patients from AMI patients with a high area under the curve (AUC) value (0.895, 95% CI, 0.802-0.988, p < 0.001).

CONCLUSIONS

Our study highlights the value of comprehensive proteomic characterization for identifying plasma proteome changes in patients with CR. This pilot study could serve as a valid foundation and initiation point for elucidation of the mechanisms of CR, which might aid in identifying effective diagnostic biomarkers in the future.

Assessing Early Atherosclerosis by Detecting and Imaging of Hypochlorous Acid and Phosphorylation Using Fluorescence Nanoprobe

The assessment of early atherosclerosis (AS) is of great significance for the early diagnosis and mechanism research. Herein, a novel nanoprobe PCN@FL is developed to realize the simultaneous detection and imaging of phosphorylation and hypochlorous acid (HClO). The selective recognition of HClO is achieved through the specific interaction between DMTC and HClO, while the levels of phosphorylation are detected via the specific interaction between Zr (IV) and phosphates. The nanoprobe can be utilized to monitor the fluctuations in HClO and phosphate in early atherosclerosis. It is observed that the levels of HClO and phosphate in the serum of early AS mice are higher than those of the normal mice. Ultimately, the levels of hypochlorous acid and phosphorylation in the inner wall of aortic vessels are imaged by two-photon microscope. The results show that the levels of HClO and phosphorylation in the early atherosclerotic mice are significantly higher than those of in normal mice. The nanoprobe provides a suitable fluorescent tool for simultaneous detection and imaging of HClO and phosphorylation, which holds promise for early atherosclerotic disease assessment.

Mechanistic insights into heat shock protein 27, a potential therapeutic target for cardiovascular diseases

Heat shock protein 27 (HSP27) is a small chaperone protein that is overexpressed in a variety of cellular stress states. It is involved in regulating proteostasis and protecting cells from multiple sources of stress injury by stabilizing protein conformation and promoting the refolding of misfolded proteins. Previous studies have confirmed that HSP27 is involved in the development of cardiovascular diseases and plays an important regulatory role in this process. Herein, we comprehensively and systematically summarize the involvement of HSP27 and its phosphorylated form in pathophysiological processes, including oxidative stress, inflammatory responses, and apoptosis, and further explore the potential mechanisms and possible roles of HSP27 in the diagnosis and treatment of cardiovascular diseases. Targeting HSP27 is a promising future strategy for the treatment of cardiovascular diseases.

Human platelets release TGFBIp in acute myocardial infarction

Transforming growth factor-β-induced protein (TGFBIp) is released from activated platelets and promotes pro-thrombotic complications like pulmonary embolism. The role of TGFBIp in acute coronary syndrome, especially with a focus on platelets, has not been investigated so far. Using ELISA and immunoblotting, we demonstrate platelet TGFBIp release in patients with myocardial infarction (MI). We investigated TGFBIp-induced platelet adhesion and rolling by flow chamber and chemotactic effects of TGFBIp in transwell experiments. Immunochemistry staining of arterial vessels detected TGFBIp and the platelet-specific protein GPVI in the vessel wall.We demonstrate for the first time that platelet TGFBIp release is significantly increased in MI and correlates with the severity of acute coronary syndromes (STEMI, NSTEMI). After activation with TRAP, platelets release TGFBIp and TGFBIp itself activates platelets. Under flow, TGFBIp-mediated platelet rolling and adherence similarly to collagen. TGFBIp significantly increased platelet transmigration and we demonstrate TGFBIp deposits in the wall of human arteries. In this study, we add novel aspects to the role of TGFBIp in acute coronary syndrome by demonstrating that TGFBIp is partially released from platelets during MI and has activating, pro-adhesive and pro-migratory effects on platelets that could contribute to the disease development of coronary vascular inflammation and MI.

Comprehensive Analysis of N6-Methyladenosine RNA Methylation Regulators Expression Identify Distinct Molecular Subtypes of Myocardial Infarction

Background: Myocardial infarction (MI) is one of the leading threats to human health. N6-methyladenosine (m6A) modification, as a pivotal regulator of messenger RNA stability, protein expression, and cellular processes, exhibits important roles in the development of cardiac remodeling and cardiomyocyte contractile function.

Methods: The expression levels of m6A regulators were analyzed using the GSE5406 database. We analyzed genome-wide association study data and single-cell sequencing data to confirm the functional importance of m6A regulators in MI. Three molecular subtypes with different clinical characteristics were established to tailor treatment strategies for patients with MI. We applied pathway analysis and differentially expressed gene (DEG) analysis to study the changes in gene expression and identified four common DEGs. Furthermore, we constructed the protein–protein interaction network and confirmed several hub genes in three clusters of MI. To lucubrate the potential functions, we performed a ClueGO analysis of these hub networks.

Results: In this study, we identified that the levels of FTO, YTHDF3, ZC3H13, and WTAP were dramatically differently expressed in MI tissues compared with controls. Bioinformatics analysis showed that DEGs in MI were significantly related to modulating calcium signaling and chemokine signaling, and m6A regulators were related to regulating glucose measurement and elevated blood glucose levels. Furthermore, genome-wide association study data analysis showed that WTAP single-nucleotide polymorphism was significantly related to the progression of MI. In addition, single-cell sequencing found that WTAP is widely expressed in the heart tissues. Moreover, we conducted consensus clustering for MI in view of the dysregulated m6A regulators’ expression in MI. According to the expression levels, we found MI patients could be clustered into three subtypes. Pathway analysis showed the DEGs among different clusters in MI were assigned to HIF-1, IL-17, MAPK, PI3K-Akt signaling pathways, etc. The module analysis detected several genes, including BAG2, BAG3, MMP2, etc. We also found that MI-related network was significantly related to positive and negative regulation of angiogenesis and response to heat. The hub networks in MI clusters were significantly related to antigen processing and ubiquitin-mediated proteolysis, RNA splicing, and stability, indicating that these processes may contribute to the development of MI.

Conclusion: Collectively, our study could provide more information for understanding the roles of m6A in MI, which may provide a novel insight into identifying biomarkers for MI treatment and diagnosis.

Bmal1 Regulates the Redox Rhythm of HSPB1, and Homooxidized HSPB1 Attenuates the Oxidative Stress Injury of Cardiomyocytes

Oxidative stress is the main cause of acute myocardial infarction (AMI), which is related to the disorder of the regulation of Bmal1 on the redox state. HSPB1 form homologous-oxidized HSPB1 (homooxidized HSPB1) to resist oxidative damage via S-thiolated modification. However, it is still unclarified whether there is an interaction between the circadian clock and HSPB1 in myocardial injury. A total of 118 AMI patients admitted and treated in our hospital from Sep. 2019 to Sep. 2020 were selected to detect the plasma HSPB1 expression and the redox state. We divided the AMI patients into three subgroups: morning-onset AMI (5 : 00 am to 8 : 00 am; Am-subgroup, n = 38), noon-onset AMI (12 : 00 pm to 15 : 00; Pm-subgroup, n = 45), and night-onset AMI (20 : 00 pm to 23 : 00 pm; Eve-subgroup, n = 35) according to the circadian rhythm of onset. The Am-subgroup had remarkably higher cardiac troponin I (cTnI), creatine kinase MB (CK-MB), and B-type natriuretic peptide (BNP) but lower left ventricular ejection fraction (LVEF) than the Pm-subgroup and Eve-subgroup. Patients complicated with cardiogenic shock were significantly higher in the Am-subgroup than in the other two groups. The homooxidized HSPB1 in plasma markedly decreased in the Am-subgroup. The HSPB1C141S mutant accelerated H9c2 cell apoptosis, increased reactive oxygen species (ROS), and decreased reduced-glutathione (GSH) and the ratio of reduced-GSH and GSSG during oxidative stress. Importantly, we found that the redox state of HSPB1 was consistent with the oscillatory rhythm of Bmal1 expression in normal C57B/L mice. The circadian rhythm disorder contributed to decrease Bmal1 and homooxidized HSPB1 in cardiomyocytes of C57BL/6 mice. In addition, Bmal1 and homooxidized HSPB1 decreased in neonatal rat cardiomyocytes exposed to H2O2. Knockdown of Bmal1 led to significant attenuation in homooxidized HSPB1 expression, whereas overexpression of Bmal1 increased homooxidized HSPB1 expression in response to H2O2. Our findings indicated that the homooxidized HSPB1 reduced probably the AMI patients' risk of shock and target organ damage, which was associated with Bmal1 regulating the redox state of HSPB1.

Phosphorylation Modifications Regulating Cardiac Protein Quality Control Mechanisms

Many forms of cardiac disease, including heart failure, present with inadequate protein quality control (PQC). Pathological conditions often involve impaired removal of terminally misfolded proteins. This results in the formation of large protein aggregates, which further reduce cellular viability and cardiac function. Cardiomyocytes have an intricately collaborative PQC system to minimize cellular proteotoxicity. Increased expression of chaperones or enhanced clearance of misfolded proteins either by the proteasome or lysosome has been demonstrated to attenuate disease pathogenesis, whereas reduced PQC exacerbates pathogenesis. Recent studies have revealed that phosphorylation of key proteins has a potent regulatory role, both promoting and hindering the PQC machinery. This review highlights the recent advances in phosphorylations regulating PQC, the impact in cardiac pathology, and the therapeutic opportunities presented by harnessing these modifications.

Extracellular Matrix-Specific Platelet Activation Leads to a Differential Translational Response and Protein De Novo Synthesis in Human Platelets

Platelets are exposed to extracellular matrix (ECM) proteins like collagen and laminin and to fibrinogen during acute vascular events. However, beyond hemostasis, platelets have the important capacity to migrate on ECM surfaces, but the translational response of platelets to different extracellular matrix stimuli is still not fully characterized. Using 2D-gel electrophoresis, confocal microscopy, polysome analysis and protein sequencing by mass spectrometry, we demonstrate that platelets show a differential expression profile of newly synthesized proteins on laminin, collagen or fibrinogen. In this context, we observed a characteristic, ECM-dependent translocation phenotype of translation initiation factor eIF4E to the ribosomal site. eIF4E accumulated in polysomes with increased binding of mRNA and co-localization with vinculin, leading to de novo synthesis of important cytoskeletal regulator proteins. As the first study, we included a proteome analysis of laminin-adherent platelets and interestingly identified upregulation of essentially important proteins that mediate cytoskeletal regulation and mobility in platelets, such as filamin A, talin, vinculin, gelsolin, coronin or kindlin-3. In summary, we demonstrate that platelet activation with extracellular matrix proteins results in a distinct stimulus-specific translational response of platelets that will help to improve our understanding of the regulation of platelet mobility and migration.

Effects of transport stress on pathological injury and main heat shock protein expression in the respiratory system of goats

The aim of the present study was to investigate the pathological injury and the expression of heat shock proteins in the caprine lung, trachea and bronchus under transport stress. 12 healthy male goats were selected and randomly divided into three groups. The control group (non-transported group), 2 hr transport-treated group and 6 hr transport-treated group. Morphological changes as well as the expression of heat shock proteins (HSPs, mainly HSP27, HSP70 and HSP90) in three parts of the respiratory tract were examined. Our results showed swollen mucosa and congestive blood vessels in mucous layer and submucosa, inflammatory cell infiltration as well as degeneration and necrosis of mucosal epithelial cells in trachea and bronchus of the transport-treated groups. The epithelial cells were degenerated, and the exfoliated cells and debris could be seen in the alveolar cavity. The results of immunohistochemistry showed that HSP27 and HSP70 were strongly expressed in tracheal and bronchial epithelium, glandular epithelium, vascular endothelium and bronchiole epithelium. And the amount of positive inflammatory cells was increased in transport-treated groups. Western blot results indicated that the expression of all three proteins had no obvious difference among the three groups in bronchi (p > .05). In trachea, there was no significant difference in the expression of heat shock proteins among the three groups except that the expression of HSP70 which was obviously higher in the two transported groups than the control group (p < .05). The expression level of HSP70 in the 2 hr transport-treated group was significantly higher than the 6 hr group (p < .05) and control groups (p < .05). However, there was no significant difference in the expression level of HSP27 and HSP90 in three groups (p > .05). In conclusion, our data showed that transport stress could damage the caprine respiratory system.

Molecular Research on Platelet Activity in Health and Disease

This editorial summarizes and discusses the themes of eleven articles (five reviews and six original studies) published in the Special Issue “Molecular Research On Platelet Activity in Health and Disease”. They give an international picture of the up-to-date understanding of (i) platelet signalling under physiological and pathological conditions, (ii) novel technologies for monitoring platelet functions and (iii) clinical applications of platelet-based-therapy for management of pathological conditions, not directly related to haemostasis and thrombosis.