The Role of ERK1/2 in the Development of Diabetic Cardiomyopathy

Insulin signaling and mitochondrial phenotype of skeletal muscle are programmed in utero by maternal diabetes

Maternal diabetes may influence glucose metabolism in adult offspring, an area with limited research on underlying mechanisms. Our study explored the impact of maternal hyperglycemia during pregnancy on insulin resistance development. Adult female Sprague-Dawley rats from control and diabetic mothers were mated, and their female offspring were monitored for 150 days. The rats were euthanized for blood and muscle samples. Maternal diabetes led to heightened insulin levels, increased HOMA-IR, elevated triglycerides, and a raised TyG index in adult offspring. Muscle samples showed a decreased protein expression of AMPK, PI3K, MAPK, DRP1, and MFF. These changes induced intergenerational metabolic programming in female pups, resulting in insulin resistance, dyslipidemia, and glucose intolerance by day 150. Findings highlight the offspring's adaptation to maternal hyperglycemia, involving insulin resistance, metabolic alterations, the downregulation of insulin signaling sensors, and disturbed mitochondrial morphology. Maintaining maternal glycemic control emerges as crucial in mitigating diabetes-associated disorders in adult offspring.

KSR1 Knockout Mouse Model Demonstrates MAPK Pathway's Key Role in Cisplatin- and Noise-induced Hearing Loss

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared with their wild-type KSR1 littermates. KSR1 is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK1/2 and ERK1/2 and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. KSR1, BRAF, MEK1/2, and ERK1/2 are all ubiquitously expressed in the cochlea. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in male and female mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, protected male and female KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induced hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

Role and molecular mechanisms of SGLT2 inhibitors in pathological cardiac remodeling (Review)

Cardiovascular diseases are caused by pathological cardiac remodeling, which involves fibrosis, inflammation and cell dysfunction. This includes autophagy, apoptosis, oxidative stress, mitochondrial dysfunction, changes in energy metabolism, angiogenesis and dysregulation of signaling pathways. These changes in heart structure and/or function ultimately result in heart failure. In an effort to prevent this, multiple cardiovascular outcome trials have demonstrated the cardiac benefits of sodium‑glucose cotransporter type 2 inhibitors (SGLT2is), hypoglycemic drugs initially designed to treat type 2 diabetes mellitus. SGLT2is include empagliflozin and dapagliflozin, which are listed as guideline drugs in the 2021 European Guidelines for Heart Failure and the 2022 American Heart Association/American College of Cardiology/Heart Failure Society of America Guidelines for Heart Failure Management. In recent years, multiple studies using animal models have explored the mechanisms by which SGLT2is prevent cardiac remodeling. This article reviews the role of SGLT2is in cardiac remodeling induced by different etiologies to provide a guideline for further evaluation of the mechanisms underlying the inhibition of pathological cardiac remodeling by SGLT2is, as well as the development of novel drug targets.

The fusion gene LRP1-SNRNP25 drives invasion and migration by activating the pJNK/37LRP/MMP2 signaling pathway in osteosarcoma

Through transcriptome sequencing, we previously identified a new osteosarcoma-specific, frequent fusion gene, LRP1-SNRNP25, and found that it played an important role in tumor cell invasion and migration. However, the specific mechanism remains unclear. In this article, whole-genome sequencing further confirmed that the LRP1-SNRNP25 fusion gene is formed by fusion of LRP1 exon 8 and SNRNP25 exon 2. In vitro, scratch and Transwell assays demonstrated that the migration and invasion abilities of LRP1-SNRNP25-overexpressing osteosarcoma cells were significantly increased. To explore the molecular mechanism of the LRP1-SNRNP25 fusion in affecting osteosarcoma cell migration and invasion, we evaluated the migration and invasion-related molecular signaling pathways by western blotting. Some migration- and invasion-related genes, including pJNK and MMP2, were upregulated. Coimmunoprecipitation-mass spectrometry showed that 37LRP can interact with pJNK. Western blotting confirmed that LRP1-SNRNP25 overexpression upregulates 37LRP protein expression. Immunofluorescence staining showed the intracellular colocalization of LRP1-SNRNP25 with pJNK and 37LRP proteins and that LRP1-SNRNP25 expression increased the pJNK and 37LRP levels. Coimmunoprecipitation (co-IP) confirmed that LRP1-SNRNP25 interacted with pJNK and 37LRP proteins. The pJNK inhibitor SP600125 dose-dependently decreased the pJNK/37LRP/MMP2 levels. After siRNA-mediated 37LRP knockdown, the MMP2 protein level decreased. These two experiments proved the upstream/downstream relationship among pJNK, 37LRP, and MMP2, with pJNK the farthest upstream and MMP2 the farthest downstream. These results proved that the LRP1-SNRNP25 fusion gene exerts biological effects through the pJNK/37LRP/MMP2 signaling pathway. In vivo, LRP1-SNRNP25 promoted osteosarcoma cell growth. Tumor growth was significantly inhibited after SP600125 treatment. Immunohistochemical analysis showed that the pJNK, MMP2, and Ki-67 protein levels were significantly increased in tumor tissues of LRP1-SNRNP25-overexpressing cell-injected nude mice. Furthermore, lung and liver metastasis were more prevalent in these mice. In a word, LRP1-SNRNP25 promotes invasion, migration, and metastasis via pJNK/37LRP/MMP2 pathway. LRP1-SNRNP25 is a potential therapeutic target for LRP1-SNRNP25-positive osteosarcoma.

Jianpi Qinghua Formula Alleviates Diabetic Myocardial Injury Through Inhibiting JunB/c-Fos Expression

OBJECTIVE

Diabetic cardiomyopathy (DCM) represents a substantial risk factor for heart failure and increased mortality in individuals afflicted with diabetes mellitus (DM). DCM typically manifests as myocardial fibrosis, myocardial hypertrophy, and impaired left ventricular diastolic function. While the clinical utility of the Jianpi Qinghua (JPQH) formula has been established in treating diabetes and insulin resistance, its potential efficacy in alleviating diabetic cardiomyopathy remains uncertain. This study aims to investigate the impact and underlying molecular mechanisms of the JPQH formula (JPQHF) in ameliorating myocardial injury in nonobese diabetic rats, specifically focusing on apoptosis and inflammation.

METHODS

Wistar rats were assigned as the normal control group (CON), while Goto-Kakizaki (GK) rats were randomly divided into three groups: DM, DM treated with the JPQHF, and DM treated with metformin (MET). Following a 4-week treatment regimen, various biochemical markers related to glucose metabolism, cardiac function, cardiac morphology, and myocardial ultrastructure in GK rats were assessed. RNA sequencing was utilized to analyze differential gene expression and identify potential therapeutic targets. In vitro experiments involved high glucose to induce apoptosis and inflammation in H9c2 cells. Cell viability was evaluated using CCK-8 assay, apoptosis was monitored via flow cytometry, and the production of inflammatory cytokines was measured using quantitative real-time PCR (qPCR) and ELISA. Protein expression levels were determined by Western blotting analysis. The investigation also incorporated the use of MAPK inhibitors to further elucidate the mechanism at both the transcriptional and protein levels.

RESULTS

The JPQHF group exhibited significant reductions in interventricular septal thickness at end-systole (IVSs) and left ventricular internal diameter at end-systole and end-diastole (LVIDs and LVIDd). JPQHF effectively suppressed high glucose-induced activation of IL-1β and caspase 3 in cardiomyocytes. Furthermore, JPQHF downregulated the expression of myocardial JunB/c-Fos, which was upregulated in both diabetic rats and high glucose-treated H9c2 cells.

CONCLUSION

The JPQH formula holds promise in mitigating diabetic myocardial apoptosis and inflammation in cardiomyocytes by inhibiting JunB/c-Fos expression through suppressing the MAPK (p38 and ERK1/2) pathway.

Studying the Roles of the Renin-Angiotensin System in Accelerating the Disease of High-Fat-Diet-Induced Diabetic Nephropathy in a db/db and ACE2 Double-Gene-Knockout Mouse Model

Diabetic nephropathy (DN) is a crucial metabolic health problem. The renin-angiotensin system (RAS) is well known to play an important role in DN. Abnormal RAS activity can cause the over-accumulation of angiotensin II (Ang II). Angiotensin-converting enzyme inhibitor (ACEI) administration has been proposed as a therapy, but previous studies have also indicated that chymase, the enzyme that hydrolyzes angiotensin I to Ang II in an ACE-independent pathway, may play an important role in the progression of DN. Therefore, this study established a model of severe DN progression in a db/db and ACE2 KO mouse model (db and ACE2 double-gene-knockout mice) to explore the roles of RAS factors in DNA and changes in their activity after short-term (only 4 weeks) feeding of a high-fat diet (HFD) to 8-week-old mice. The results indicate that FD-fed db/db and ACE2 KO mice fed an HFD represent a good model for investigating the role of RAS in DN. An HFD promotes the activation of MAPK, including p-JNK and p-p38, as well as the RAS signaling pathway, leading to renal damage in mice. Blocking Ang II/AT1R could alleviate the progression of DN after administration of ACEI or chymase inhibitor (CI). Both ACE and chymase are highly involved in Ang II generation in HFD-induced DN; therefore, ACEI and CI are potential treatments for DN.

Chrysin-based supramolecular cyclodextrin-calixarene drug delivery system: a novel approach for attenuating cardiac fibrosis in chronic diabetes

Introduction: Cardiac fibrosis is strongly induced by diabetic conditions. Both chrysin (CHR) and calixarene OTX008, a specific inhibitor of galectin 1 (Gal-1), seem able to reduce transforming growth factor beta (TGF-β)/SMAD pro-fibrotic pathways, but their use is limited to their low solubility. Therefore, we formulated a dual-action supramolecular system, combining CHR with sulfobutylated β-cyclodextrin (SBECD) and OTX008 (SBECD + OTX + CHR). Here we aimed to test the anti-fibrotic effects of SBECD + OTX + CHR in hyperglycemic H9c2 cardiomyocytes and in a mouse model of chronic diabetes. Methods: H9c2 cardiomyocytes were exposed to normal (NG, 5.5 mM) or high glucose (HG, 33 mM) for 48 h, then treated with SBECD + OTX + CHR (containing OTX008 0.75-1.25-2.5 µM) or the single compounds for 6 days. TGF-β/SMAD pathways, Mitogen-Activated Protein Kinases (MAPKs) and Gal-1 levels were assayed by Enzyme-Linked Immunosorbent Assays (ELISAs) or Real-Time Quantitative Reverse Transcription Polymerase chain reaction (qRT-PCR). Adult CD1 male mice received a single intraperitoneal (i.p.) administration of streptozotocin (STZ) at a dosage of 102 mg/kg body weight. From the second week of diabetes, mice received 2 times/week the following i.p. treatments: OTX (5 mg/kg)-SBECD; OTX (5 mg/kg)-SBECD-CHR, SBECD-CHR, SBECD. After a 22-week period of diabetes, mice were euthanized and cardiac tissue used for tissue staining, ELISA, qRT-PCR aimed to analyse TGF-β/SMAD, extracellular matrix (ECM) components and Gal-1. Results: In H9c2 cells exposed to HG, SBECD + OTX + CHR significantly ameliorated the damaged morphology and reduced TGF-β1, its receptors (TGFβR1 and TGFβR2), SMAD2/4, MAPKs and Gal-1. Accordingly, these markers were reduced also in cardiac tissue from chronic diabetes, in which an amelioration of cardiac remodeling and ECM was evident. In both settings, SBECD + OTX + CHR was the most effective treatment compared to the other ones. Conclusion: The CHR-based supramolecular SBECD-calixarene drug delivery system, by enhancing the solubility and the bioavailability of both CHR and calixarene OTX008, and by combining their effects, showed a strong anti-fibrotic activity in rat cardiomyocytes and in cardiac tissue from mice with chronic diabetes. Also an improved cardiac tissue remodeling was evident. Therefore, new drug delivery system, which could be considered as a novel putative therapeutic strategy for the treatment of diabetes-induced cardiac fibrosis.

Diabetic state of human coronary artery endothelial cells results in altered effects of bone mesenchymal stem cell-derived extracellular vesicles

Human bone mesenchymal stem cell-derived extracellular vesicles (HBMSC-EV) have been used successfully in animal models of myocardial ischemia, yet have dampened effects in metabolic syndrome through unknown mechanisms. This study demonstrates the basal differences between non-diabetic human coronary artery endothelial cells (HCAEC) and diabetic HCAEC (DM-HCAEC), and how these cells respond to the treatment of HBMSC-EV. HCAEC and DM-HCAEC were treated with HBMSC-EV for 6 h. Proteomics, western blot analysis, and tube formation assays were performed. Key metabolic, growth, and stress/starvation cellular responses were significantly altered in DM-HCAEC in comparison to that of HCAEC at baseline. Proteomics demonstrated increased phosphorus metabolic process and immune pathways and decreased RNA processing and biosynthetic pathways in DM-HCAEC. Similar to previous in vivo findings, HCAEC responded to the HBMSC-EV with regenerative and anti-inflammatory effects through the upregulation of multiple RNA pathways and downregulation of immune cell activation pathways. In contrast, DM-HCAEC had a significantly diminished response to HBMSC-EV, likely due to the baseline abnormalities in DM-HCAEC. To achieve the full benefits of HBMSC-EV and for a successful transition of this potential therapeutic agent to clinical studies, the abnormalities found in DM-HCAEC will need to be further studied.

KSR1 knockout mouse model demonstrates MAPK pathway's key role in cisplatin- and noise-induced hearing loss

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared to their wild-type KSR1 littermates. KSR1 is expressed in the cochlea and is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK and ERK and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, downregulated the MAPK kinase cascade and protected the KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, as excepted, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induce hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

Sex differences in the cardiac stress response following SARS-CoV-2 infection of ferrets

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection damages the heart, increasing the risk of adverse cardiovascular events. Female sex protects against complications of infection; females are less likely to experience severe illness or death, although their risk for postacute sequelae of COVID-19 ("long COVID") is higher than in males. Despite the important role of the heart in COVID-19 outcomes, molecular elements in the heart impacted by SARS-CoV-2 are poorly understood. Similarly, the role sex has on the myocardial effects of SARS-CoV-2 infection has not been investigated at a molecular level. We intranasally inoculated female and male ferrets with SARS-CoV-2 and assessed myocardial stress signals, inflammation, and the innate immune response for 14 days. Myocardial phosphorylated GSK3α/β decreased at day 2 postinfection (pi) in male ferrets, whereas females showed no changes. Myocardial levels of p62/SQSTM1 decreased in male ferrets at days 2, 7, and 14 pi while lower baseline levels in females increased on day 2. Phosphorylated ERK1/2 increased in cardiomyocyte nuclei in females on days 2 and 14 pi, whereas male ferrets had no changes. Only hearts from females increased fibrosis on day 14 pi. Immune and inflammation markers increased in hearts, with some sex differences. These results are the first to identify myocardial stress responses following SARS-CoV-2 infection and reveal sex differences that may contribute to differential outcomes. Future research is required to define the pathways involving these stress signals to fully understand the myocardial effects of COVID-19 and identify targets that mitigate cardiac injury following SARS-CoV-2 infection.NEW & NOTEWORTHY Cardiovascular disease is a leading risk factor for severe COVID-19, and cardiovascular pathologies are among the most common adverse outcomes following SARS-CoV-2 infection. Females and males have different outcomes and adverse cardiovascular events following SARS-CoV-2 infection. This study shows sex differences in stress proteins p62/SQSTM1, ERK1/2, and GSK3α/β, along with innate immunity and inflammation in hearts of ferrets infected with SARS-CoV-2, identifying mechanisms of COVID-19 cardiac injury and cardiac complications of long COVID.

Linderalactone mitigates diabetic cardiomyopathy in mice via suppressing the MAPK/ATF6 pathway

Diabetic cardiomyopathy (DCM) is a challenging diabetic complication that manifests as chronic inflammation. Yet, the mechanism underlying diabetes-associated myocardial injury is not fully understood. We investigated the pharmacological effects and mechanisms of linderalactone, a natural compound that can prevent diabetes-induced cardiomyopathy in mice. Diabetes was induced by a single dose of streptozotocin (120 mg/kg, i.p.). Diabetic mice were administrated with linderalactone (2.5 or 5 mg/kg) by gavage for five weeks. Harvested heart tissues were then subjected to RNA-sequencing analysis to explore the potential mechanism of linderalactone. Linderalactone prevented heart dysfunction by inhibiting myocardial hypertrophy, fibrosis, and inflammation, without altering blood glucose. RNA-sequencing indicated that linderalactone exerted its cardioprotective effects mainly by affecting the mitogen-activated protein kinase (MAPK)/ activating transcription factor 6 (ATF6) pathway. Linderalactone also suppressed endoplasmic reticulum (ER) stress mediated by the diabetes-activated MAPKs/ATF6 pathway, thereby reducing myocardial hypertrophy and inflammation in heart tissues and in cultured cardiomyocytes. Inhibition of MAPKs or a deficiency of ATF6 in cardiomyocytes mimicked the linderalactone-associated decreases in high glucose-induced hypertrophy and inflammation. Linderalactone showed beneficial effects in alleviating diabetic cardiomyopathy, in part by modulating the MAPK/ATF6 signaling pathway to mitigate myocardial hypertrophy and inflammation. Linderalactone may have clinical utility in the treatment for diabetes-associated cardiomyopathy.

ERK1/2 Inhibition Alleviates Noise-Induced Hearing Loss While Tempering Down the Immune Response

Noise-induced hearing loss (NIHL) is a major cause of hearing impairment, yet no FDA-approved drugs exist to prevent it. Targeting the mitogen activated protein kinase (MAPK) cellular pathway has emerged as a promising approach to attenuate NIHL. Tizaterkib is an orally bioavailable, highly specific ERK1/2 inhibitor, currently in Phase-1 anticancer clinical trials. Here, we tested tizaterkib's efficacy against permanent NIHL in mice at doses equivalent to what humans are currently prescribed in clinical trials. The drug given orally 24 hours after noise exposure, protected an average of 20-25 dB SPL in three frequencies, in female and male mice, had a therapeutic window >50, and did not confer additional protection to KSR1 genetic knockout mice, showing the drug works through the MAPK pathway. Tizaterkib shielded from noise-induced cochlear synaptopathy, and a 3-day, twice daily, treatment with the drug was the optimal determined regimen. Importantly, tizaterkib was shown to decrease the number of CD45 and CD68 positive immune cells in the cochlea following noise exposure, which could be part of the protective mechanism of MAPK inhibition.

MircroRNA-145 Attenuates Cardiac Fibrosis Via Regulating Mitogen-Activated Protein Kinase Kinase Kinase 3

PURPOSE

This study aimed to explore the effect of microRNA (miR)-145 on cardiac fibrosis in heart failure mice and its target.

METHODS

Experiments were carried out in mice receiving left coronary artery ligation, transverse aortic constriction (TAC), or angiotensin (Ang) II to trigger heart failure, and in cardiac fibroblasts (CFs) with Ang II-induced fibrosis.

RESULTS

The miR-145 levels were decreased in the mice hearts of heart failure induced by myocardial infarction (MI), TAC or Ang II infusion, and in the Ang II-treated CFs. The impaired cardiac function was ameliorated by miR-145 agomiR in MI mice. The increased fibrosis and the levels of collagen I, collagen III, and transforming growth factor-beta (TGF-β) in MI mice were inhibited by miR-145 agomiR or miR-145 transgene (TG). The agomiR of miR-145 also attenuated the increases of collagen I, collagen III, and TGF-β in Ang II-treated CFs. Bioinformatics analysis and luciferase reporter assays indicated that mitogen-activated protein kinase kinase kinase 3 (MAP3K3) was a direct target gene of miR-145. MAP3K3 expression was suppressed by MiR-145 in CFs, while the MAP3K3 over-expression reversed the inhibiting effects of miR-145 agomiR on the Ang II-induced increases of collagen I, collagen III, and TGF-β in CFs.

CONCLUSION

These results indicated that miR-145 upregulation could improve cardiac dysfunction and cardiac fibrosis by inhibiting MAP3K3 in heart failure. Thus, upregulating miR-145 or blocking MAP3K3 can be used to treat heart failure and cardiac fibrosis.

Diabetic cardiomyopathy: Early diagnostic biomarkers, pathogenetic mechanisms, and therapeutic interventions

Diabetic cardiomyopathy (DCM) mainly refers to myocardial metabolic dysfunction caused by high glucose, and hyperglycemia is an independent risk factor for cardiac function in the absence of coronary atherosclerosis and hypertension. DCM, which is a severe complication of diabetes, has become the leading cause of heart failure in diabetic patients. The initial symptoms are inconspicuous, and patients gradually exhibit left ventricular dysfunction and eventually develop total heart failure, which brings a great challenge to the early diagnosis of DCM. To date, the underlying pathological mechanisms of DCM are complicated and have not been fully elucidated. Although there are therapeutic strategies available for DCM, the treatment is mainly focused on controlling blood glucose and blood lipids, and there is a lack of effective drugs targeting myocardial injury. Thus, a large percentage of patients with DCM inevitably develop heart failure. Given the neglected initial symptoms, the intricate cellular and molecular mechanisms, and the lack of available drugs, it is necessary to explore early diagnostic biomarkers, further understand the signaling pathways involved in the pathogenesis of DCM, summarize the current therapeutic strategies, and develop new targeted interventions.

Mechanism of fibroblast growth factor 21 in cardiac remodeling

Cardiac remodeling is a basic pathological process that enables the progression of multiple cardiac diseases to heart failure. Fibroblast growth factor 21 is considered a regulator in maintaining energy homeostasis and shows a positive role in preventing damage caused by cardiac diseases. This review mainly summarizes the effects and related mechanisms of fibroblast growth factor 21 on pathological processes associated with cardiac remodeling, based on a variety of cells of myocardial tissue. The possibility of Fibroblast growth factor 21 as a promising treatment for the cardiac remodeling process will also be discussed.

Polygonum orientale L. Alleviates Myocardial Ischemia-Induced Injury via Activation of MAPK/ERK Signaling Pathway

Although Polygonum orientale L. (PO) has a beneficial effect on treatment of myocardial ischemia (MI), its mechanism remains unclear. This study aimed to explore the pharmacological mechanism of PO against MI through MAPK signaling pathways. Firstly, the therapeutic effect of PO was evaluated for treatment of MI mice. Using Western blot and immunohistochemistry, the influence of PO on MAPK signaling pathways and cell apoptosis was investigated. Subsequently, one key pathway (ERK) of MAPK signaling pathways was screened out, on which PO posed the most obvious impact. Finally, an inhibitor of ERK1/2 was utilized to further verify the regulatory effect of PO on the MAPK/ERK signaling pathway. It was found that PO could reduce the elevation of the ST segment; injury of heart tissue; the activity of LDH, CK, NOS, cNOS and iNOS and the levels of NO, BNP, TNF-α and IL-6. It is notable that PO could significantly modulate the protein content of p-ERK/ERK in mice suffering from MI but hardly had an effect on p-JNK/JNK and p-p38/p38. Additionally, the expressions of bax, caspase3 and caspase9 were inhibited in heart tissue in the PO-treated group. To evaluate whether ERK1/2 inhibitor (PD98059) could block the effect of PO on treatment of MI, both PO and PD98059 were given to mice with MI. It was discovered that the inhibitor indeed could significantly reverse the regulatory effects of PO on the above indicators, indicating that PO could regulate p-ERK/ERK. This study provides experimental evidence that PO extenuates MI injury, cardiomyocyte apoptosis and inflammation by activating the MAPK/ERK signaling pathway.

Analysis of Function Role and Long Noncoding RNA Expression in Chronic Heart Failure Rats Treated with Hui Yang Jiu Ji Decoction

Hui Yang Jiu Ji (HYJJ) decoction has been applied as a prescription of traditional Chinese medicine for the treatment of chronic heart failure (CHF). However, its comprehensive molecular mechanism remains unclear now. Our study aimed to explore the possible function and lncRNA-miRNA regulation networks of HYJJ on CHF induced by doxorubicin (DOX) in rats. Our study showed that HYJJ could recover cardiac function and alleviate myocardial injury of DOX-induced CHF. Besides, HYJJ had an effect on restraining myocardial apoptosis in CHF rats. Moreover, RNA-sequencing and bioinformatics analysis indicated that among a total of 548 significantly up- and down-regulated differentially expressed (DE) long noncoding RNA (lncRNA), 511 up- and down-regulated DE miRNAs were identified. Cushing's syndrome and Adrenergic signaling in cardiomyocytes were common pathways between DE-lncRNAs-enriched pathways and DE-miRNAs-enriched pathways. Finally, we observed a new pathway-MSTRG.598.1/Lilrb2 pathway with the HYJJ treatment; however, it needs further studies. In conclusion, this study provided evidence that HYJJ may be a suitable medicine for treating CHF. Moreover, several pivotal miRNAs may serve important roles in these processes by regulating some key miRNAs or pathways in CHF.

Targeted activation of ERK1/2 reduces ischemia and reperfusion injury in hyperglycemic myocardium by improving mitochondrial function

Background

Diabetes can increase the risk of coronary heart disease, and also increase the mortality rate of coronary heart disease in diabetic patients. Although reperfusion therapy can preserve the viable myocardium, fatal reperfusion injury can also occur. Studies have shown that diabetes can aggravate myocardial ischemia-reperfusion injury, ERK1/2 can reduce myocardial ischemia-reperfusion injury, but its mechanism in hyperglycemic myocardial ischemia-reperfusion injury is unclear. This study sought to explore the mechanism of extracellular signal-regulated kinase 1/2 (ERK1/2) in hyperglycemic myocardial ischemia reperfusion (I/R) injury.

Methods

H9C2 cardiomyocytes were treated with high-glucose (HG) medium plus I/R stimulation to establish a hyperglycemia I/R model in vitro. The cells were treated with LM22B-10 (an ERK activator) or transfected with the constitutive activation of the mitogen-activated protein kinase 1 (CaMEK) gene. Myocardial cell apoptosis, mitochondria functional-related indicators, the oxidative stress indexes, and the expression levels of ERK1/2 protein were detected.

Results

The HG I/R injury intervention caused an increase in the ratio of apoptotic cardiomyocytes (P<0.05), but the phosphorylation level of the ERK1/2 protein did not increase further. Administering LM22B-10 or transfecting the CaMEK gene significantly activated the phosphorylation levels of ERK1/2 protein and reduced the proportion of cardiomyocyte apoptosis (P<0.05). HG I/R injury increased mitochondrial fission and reduced membrane potential. The intervention reduced the number of punctate mitochondria, increased the average network structure size and median branch length (P<0.01), increased the median network structure size and average branch length (P<0.05), and reduced the colocalization of Drp1 (Dynamin-Related protein1)/TOMM20 (Mitochondrial outer membrane translocation enzyme 20) (P<0.05) and Drp1 with serine 616 phosphorylation (Drp1s616) phosphorylation (P<0.01), thereby reducing mitochondrial fission, increasing membrane potential and mitochondrial function. HG I/R injury increased the level of oxidative stress, while administering LM22B-10 or transfecting the CaMEK gene reduced the level of oxidative stress (P<0.01).

Conclusions

Targeting the activation of ERK1/2 protein phosphorylation reduced mitochondrial fission, increased membrane potential and mitochondrial function, reduced oxidative stress and myocardial cell apoptosis, and alleviated hyperglycemia myocardial I/R injury.

Investigating Celastrol's Anti-DCM Targets and Mechanisms via Network Pharmacology and Experimental Validation

Methods

Data from TCMSP and GEO databases were utilized to identify targets for Celastrol on DCM. The relationship between the major targets and conventional glycolipid metabolism was obtained with Spearman correlation analysis. Experiments on animals were conducted utilizing healthy control (HC), low-dose Celastrol interventions (CL), and no intervention groups (NC), all of which had 8 SD rats in each group. To study alterations in signaling molecules, RT-PCR was performed.

Results

There were 76 common targets and 5 major targets for Celastrol-DCM. Celastrol have been found to regulate AGE-RAGE, TNF, MAPK, TOLL-like receptors, insulin resistance, and other signaling pathways, and they are closely linked to adipocytokines, fatty acid metabolism, glycolipid biosynthesis, and glycosylphosphati-dylinositol biosynthesis on DCM. These five major targets have been found to regulate these pathways. Experiments on rats indicated that P38 MAPK was considerably elevated in the cardiac tissue from rats in the CL and NC groups compared to the HC group, and the difference was statistically significant (P < 0.01). Significant differences were seen between the CL and NC groups in P38 MAPK levels, with a statistical significance level of less than 0.05.

Conclusion

Celastrol may play a role in reversing energy remodeling, anti-inflammation, and oxidative stress via modulating p38 protein expression in the MAPK pathway, which have been shown in the treatment of DCM.

Connecting Genomics and Proteomics to Identify Protein Biomarkers for Adult and Youth-Onset Type 2 Diabetes: A Two-Sample Mendelian Randomization Study

Type 2 diabetes shows an increasing prevalence in both adults and children. Identification of biomarkers for both youth and adult-onset type 2 diabetes is crucial for development of screening tools or drug targets. In this study, using two-sample Mendelian randomization (MR), we identified 22 circulating proteins causally linked to adult type 2 diabetes and 11 proteins with suggestive evidence for association with youth-onset type 2 diabetes. Among these, colocalization analysis further supported a role in type 2 diabetes for C-type mannose receptor 2 (MR odds ratio [OR] 0.85 [95% CI 0.79-0.92] per genetically predicted SD increase in protein level), MANS domain containing 4 (MR OR 0.90 [95% CI 0.88-0.92]), sodium/potassium-transporting ATPase subunit β2 (MR OR 1.10 [95% CI 1.06-1.15]), endoplasmic reticulum oxidoreductase 1β (MR OR 1.09 [95% CI 1.05-1.14]), spermatogenesis-associated protein 20 (MR OR 1.12 [95% CI 1.06-1.18]), haptoglobin (MR OR 0.96 [95% CI 0.94-0.98]), and α1-3-N-acetylgalactosaminyltransferase and α1-3-galactosyltransferase (MR OR 1.04 [95% CI 1.03-1.05]). Our findings support a causal role in type 2 diabetes for a set of circulating proteins, which represent promising type 2 diabetes drug targets.

Effects of thymoquinone against angiotensin II‑induced cardiac damage in apolipoprotein E‑deficient mice

Herbal medicines have attracted much attention in recent years and are increasingly being used as alternatives to pharmaceutical medicines. Thymoquinone (TQ) is one of the most active ingredients in Nigella sativa seeds, which has several beneficial properties, including anti‑inflammatory, anti‑oxidative stress, anti‑hypertensive, anti‑apoptotic and free radical‑scavenging effects. Angiotensin II (Ang II) is involved in cardiovascular diseases. The present study aimed to investigate the potential protective effects of TQ against Ang II‑induced cardiac damage in apolipoprotein E‑deficient (ApoE‑/‑) mice. Briefly, 8‑week‑old male ApoE‑/‑ mice were randomly divided into four groups: Control, TQ, Ang II and Ang II + TQ groups. Osmotic minipumps, filled with either a saline vehicle or an Ang II solution (1,000 ng/kg/min), were implanted in ApoE‑/‑ mice for up to 4 weeks. The serum levels of high‑sensitivity C‑reactive protein (hs‑CRP) and histopathological alterations in heart tissue were assessed. In addition, the mRNA and protein expression levels of molecules associated with fibrosis (collagen I and III), oxidative stress and apoptosis (Nox4 and p53), and inflammation [tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β and IL‑6] were analyzed by reverse transcription‑quantitative PCR (RT‑qPCR) and western blotting. In the in vitro study, H9c2 cells were incubated with different concentrations of Ang II, and the expression levels of pro‑inflammatory cytokines were evaluated using RT‑qPCR, whereas the protein expression levels of phosphorylated‑extracellular signal‑regulated kinase (p‑ERK) were determined using western blotting. Western blotting was also performed to detect the expression levels of collagen I, collagen III, Nox4 and p53 in H9c2 cells. The results revealed that TQ inhibited the Ang II‑induced increases in serum hs‑CRP levels. TQ also significantly inhibited the high levels of TNF‑α, IL‑1β, IL‑6, collagen I, collagen III, Nox4 and p53 in Ang II‑treated mice. Furthermore, TQ protected against Ang II‑induced cardiac damage by inhibiting inflammatory cell infiltration, proinflammatory cytokine expression, fibrosis, oxidative stress and apoptosis by suppressing activation of the p‑ERK signaling pathway. In conclusion, TQ could be considered a potential therapeutic agent for Ang II‑induced cardiac damage.

STAT4 regulates cardiomyocyte apoptosis in rat models of diabetic cardiomyopathy

OBJECTIVE

This study aimed to investigate the protective role of the signal transducer and activator of transcription 4 (STAT4) in diabetic cardiomyopathy.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats (6-8 weeks old) were purchased from the Experimental Animal Center of Zhengzhou University. The rats were randomly divided into the control and diabetic cardiomyopathy groups. Rat models of diabetic cardiomyopathy were established by a high-sugar and high-fat diet combined with a peritoneal injection of streptozocin. Pathological changes in the heart were visualized using Hematoxylin-eosin (HE) staining and Masson's staining. Moreover, cell apoptosis was detected using terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labeling (TUNEL) staining and Annexin V apoptosis detection kit. Furthermore, H9C2 cells were transfected with lentivirus overexpressing STAT4 and treated with high glucose. The CCK-8 assay was performed to determine cell viability. Finally, Western blotting was used to determine the expression of STAT4, Bax, and Bcl-2.

RESULTS

The myocardial tissue of the diabetic cardiomyopathy models showed hypertrophy, myocardial fibrosis and collagen deposition. Furthermore, TUNEL staining showed increased apoptosis and decreased expression of STAT4 in the myocardial cells. Moreover, the myocardial tissues of the DCM models showed increased expression of Bax/Bcl-2 and a high percentage of Annexin V positive cells. The H9C2 cells showed decreased expression of STAT4 following high glucose treatment. However, the H9C2 cells overexpressing STAT4 showed decreased expression of Bax/Bcl-2 and reduced percentage of Annexin V positive cells.

CONCLUSION

The DCM group had decreased myocardial expression of STAT4. Furthermore, overexpression of STAT4 was shown to reduce high glucose-induced apoptosis.

Identification and Analysis of Hub Genes in Diabetic Cardiomyopathy: Potential Role of Cytochrome P450 1A1 in Mitochondrial Metabolism and STZ-Induced Myocardial Dysfunction

Diabetic cardiomyopathy (DCM) is a primary cause of death in diabetic patients; however, its molecular mechanism is not yet clear, and there is no uniform standard for diagnosis. The aim of this study is to discover the pathogenesis and potential therapeutic targets of DCM through screening and analysis of differentially expressed genes (DEGs) in heart ventricles of DCM, and to testify the role of key hub genes in DCM-induced myocardial dysfunction. Datasets GSE4745 and GSE6880 were downloaded from the GEO database. The difference analysis, visual analysis, cluster analysis and enrichment analysis were performed by using R language, python scripts and bioinformatics software followed by the construction of protein-protein interaction (PPI) network to obtain hub genes. The DCM models were established by streptozocin (STZ) injection to the male mice. The cardiac function and the expressions of hub genes were examined by using echocardiography and real-time quantitative poly-merase chain reaction (RT-qPCR), followed by multiple statistical analyses. Bioinformatic results indicate that mitochondrial dysfunction, disturbed lipid metabolism and decreased collagen synthesis are the main causes of the DCM development. In particular, the hub gene Cyp1a1 that encodes Cytochrome P450 1A1 (CYP4501A1) enzyme has the highest connectivity in the interaction network, and is associated with mitochondrial homeostasis and energy metabolism. It plays a critical role in the oxidation of endogenous or exogenous substrates. Our RT-qPCR results confirmed that ventricular Cyp1a1 mRNA level was nearly 12-fold upregulated in DCM model compared to normal control, which was correlated with abnormal cardiac function in diabetic individuals. CYP4501A1 protein expression in mitochondria was also increased in diabetic hearts. However, we found no significant changes in collagen expressions in cardiac ventricles of mice with DCM. This study provided compact data support for understanding the pathogenesis of DCM. CYP4501A1 might be considered as a potential candidate targeting for DCM therapy. Follow-up animal and clinical verifications need to be further explored.

Sodium Glucose Cotransporter 1 (SGLT1) Inhibitors in Cardiovascular Protection: Mechanism Progresses and Challenges

In recent years, multiple clinical trials have shown that sodium glucose cotransporter 1 (SGLT1) inhibitors have significant beneficial cardiovascular effects. This includes reducing the incidence of cardiovascular deaths and heart failure hospitalizations in people with and without diabetes, as well as those with and without generalized heart failure. The exact mechanism responsible for these beneficial effects is not completely understood. To explain the cardiovascular protective effects of SGLT1 inhibitors, several potential arguments have been proposed, including decreasing oxidative stress, regulating cardiac glucose uptake, preventing ischemia/reperfusion injury, alleviating the activation of cardiac fibroblasts, attenuating apoptosis, reducing intermittent high glucose-induced pyroptosis, ameliorating cardiac hypertrophy, attenuating arrhythmic vulnerabilities, and improving left ventricular systolic disorder. This article reviews the advantages and disadvantages of these mechanisms, and attempts to synthesize and prioritize mechanisms related to the reduction of clinical events.

Curculigoside Ameliorates Bone Loss by Influencing Mesenchymal Stem Cell Fate in Aging Mice

Senile osteoporosis is characterized by increased bone loss and fat accumulation in marrow. Curculigoside (CCG) is the major bioactive component of Curculigo orchioides, which has been used as anti-osteoporosis therapy for elder patients since antiquity. We aimed to investigate the underlying mechanisms by which CCG regulated the bone-fat balance in marrow of aging mice. In our study, CCG treatment was identified to interfere with the stem cell lineage commitment both in vivo and in vitro. In vivo, CCG promoted the transcriptional co-activator with PDZ-binding motif (TAZ) expression to reverse age-related bone loss and marrow adiposity. In vitro, proper concentration of CCG upregulated TAZ expression to increase osteogenesis and decrease adipogenesis of bone marrow mesenchymal stem cells (BMSCs). This regulating effect was discounted by TAZ knockdown or the use of MEK-ERK pathway inhibitor, UO126. Above all, our study confirmed the rescuing effects of CCG on the differential shift from adipogenesis to osteogenesis of BMSCs in aging mice and provided a scientific basis for the clinical use of CCG in senile osteoporosis.

The role of FGF21 in the pathogenesis of cardiovascular disease

ABSTRACT

The morbidity and mortality of cardiovascular diseases (CVDs) are increasing worldwide and seriously threaten human life and health. Fibroblast growth factor 21 (FGF21), a metabolic regulator, regulates glucose and lipid metabolism and may exert beneficial effects on the cardiovascular system. In recent years, FGF21 has been found to act directly on the cardiovascular system and may be used as an early biomarker of CVDs. The present review highlights the recent progress in understanding the relationship between FGF21 and CVDs including coronary heart disease, myocardial ischemia, cardiomyopathy, and heart failure and also explores the related mechanism of the cardioprotective effect of FGF21. FGF21 plays an important role in the prediction, treatment, and improvement of prognosis in CVDs. This cardioprotective effect of FGF21 may be achieved by preventing endothelial dysfunction and lipid accumulating, inhibiting cardiomyocyte apoptosis and regulating the associated oxidative stress, inflammation and autophagy. In conclusion, FGF21 is a promising target for the treatment of CVDs, however, its clinical application requires further clarification of the precise role of FGF21 in CVDs.

Environmental level bisphenol A accelerates alterations of the reno-cardiac axis by the MAPK cascades in male diabetic rats: An analysis based on transcriptomic profiling and bioinformatics

In humans and animal models, the kidneys and cardiovascular systems are negatively affected by BPA from the environment. It is considered that BPA have some potential estrogen-like and non-hormone-like properties. In this study, RNA-sequencing and its-related bioinformatics was used as the basic strategy to clarify the characteristic mechanisms of kidney-heart axis remodeling and dysfunction in diabetic male rats under BPA exposure. We found that continuous BPA exposure in diabetic rats aggravated renal impairment, and caused hemodynamic disorders and dysfunctions. There were 655 and 125 differentially expressed genes in the kidney and heart, respectively. For the kidneys, functional annotation and enrichment, and gene set enrichment analyses identified bile acid secretion related to lipid synthesis and transport, and MAPK cascade pathways. For the heart, these bioinformatics analyses clearly pointed to MAPKs pathways. A total of 12 genes and another total of 6 genes were identified from the kidney tissue and heart tissue, respectively. Western blotting showed that exposure to BPA activated MAPK cascades in both organs. In this study, the exacerbated remodeling of diabetic kidney-heart axis under BPA exposure and diabetes might occur through hemodynamics, metabolism disorders, and the immune-inflammatory response, as well as continuous estrogen-like stimulation, with focus on the MAPK cascades.

Klotho protects against diabetic kidney disease via AMPK- and ERK-mediated autophagy

BACKGROUND

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and results in serious public health problems. Although a great number of studies have been performed to elucidate the mechanisms of this disease, these mechanisms remain largely unknown.

METHODS

Cell and animal models were first constructed using human renal proximal tubule cells stimulated by high glucose (HG) and mice induced by streptozotocin (STZ). After Klotho overexpression, Klotho expression was assessed by RT-PCR and western blot, immunofluorescence; autophagy and AMPK/ERK proteins were confirmed using western blot or immunohistochemical assay; the autophagosomes were observed by transmission electron microscope; the pathological structure, fibrosis, polysaccharides and glycogen of kidney were evaluated by H&E staining, Masson staining and PAS staining.

RESULTS

We first confirmed that Klotho expression and autophagic activity were reduced in DM mice and HG-induced human renal proximal tubule cells. Besides, overexpression of Klotho could significantly enhance autophagy and AMPK and ERK1/2 activities in vivo and in vitro, which also could be abolished by selective AMPK inhibitor and ERK activator. Moreover, we proved that Klotho could inhibit hyperglycemia-induced renal tubular damage.

CONCLUSION

In summary, our results proved that Klotho improved renal tubular cell autophagy via the AMPK and ERK pathways and played a role in renal protection. These findings provide new insight into the mechanism of Klotho and autophagy in DKD.

Effects of Yiqi Huoxue Decoction on Post-Myocardial Infarction Cardiac Nerve Remodeling and Cardiomyocyte Hypertrophy in Rats

Myocardial infarction can lead to ventricular remodeling and arrhythmia, which is closely related to nerve remodeling. Our previous study found that Yiqi Huoxue decoction (YQHX) can improve ventricular remodeling and reduce myocardial damage. Therefore, in this study, we observed the effect of YQHX on cardiac neural remodeling and cardiomyocyte hypertrophy and its possible mechanism. This research is composed of two parts: animal and H9c2 cells experiments. The animal model of acute myocardial infarction was established by ligating the left anterior descending coronary artery in Sprague Dawley (SD) rats. H9c2 cells were placed in 94% N₂, 5% CO₂, and 1% O₂ hypoxic environment for 12 hours to replicate the hypoglycemic hypoxia model. The experimental results showed that, compared with the MI group, YQHX can significantly improve heart function after myocardial infarction and reduce nerve remodeling and myocardial hypertrophy. Pathological structure observation demonstrated reducing myocardial tissue damage and decreasing of cell cross-sectional area, diameter, and circumference. The positive rate of TH declined apparently, and the sympathetic nerve density was lower than that of the MI group. After YQHX was given for 28 days, the proneural remodeling factors TH, NGF, and GAP43 in the marginal zone of infarction and stellate ganglion decreased obviously while the inhibitory nerve remodeling factor Sema-3A increased. The myocardial hypertrophic protein ANP and β-MHC were also significantly inhibited with p-ERK1/2 protein expression level prominently reduced. There was no difference between the YQHX group and the Meto group. After myocardial infarction, nerve remodeling was seen in the marginal area of infarction and stellate ganglion, and the neuropeptides released by which promoted myocardial hypertrophy. The mechanism may be related to the ERK1/2 signaling pathway. YQHX could regulate the ERK1/2 signaling pathway, inhibit the release of nerve remodeling factors and myocardial hypertrophy protein to reduce nerve remodeling, and relieve myocardial hypertrophy.

Fibrosis of the diabetic heart: Clinical significance, molecular mechanisms, and therapeutic opportunities

In patients with diabetes, myocardial fibrosis may contribute to the pathogenesis of heart failure and arrhythmogenesis, increasing ventricular stiffness and delaying conduction. Diabetic myocardial fibrosis involves effects of hyperglycemia, lipotoxicity and insulin resistance on cardiac fibroblasts, directly resulting in increased matrix secretion, and activation of paracrine signaling in cardiomyocytes, immune and vascular cells, that release fibroblast-activating mediators. Neurohumoral pathways, cytokines, growth factors, oxidative stress, advanced glycation end-products (AGEs), and matricellular proteins have been implicated in diabetic fibrosis; however, the molecular links between the metabolic perturbations and activation of a fibrogenic program remain poorly understood. Although existing therapies using glucose- and lipid-lowering agents and neurohumoral inhibition may act in part by attenuating myocardial collagen deposition, specific therapies targeting the fibrotic response are lacking. This review manuscript discusses the clinical significance, molecular mechanisms and cell biology of diabetic cardiac fibrosis and proposes therapeutic targets that may attenuate the fibrotic response, preventing heart failure progression.

Crosstalk of Diabetic Conditions with Static Versus Dynamic Flow Environment-Impact on Aortic Valve Remodeling

Type 2 diabetes mellitus (T2D) is one of the prominent risk factors for the development and progression of calcific aortic valve disease. Nevertheless, little is known about molecular mechanisms of how T2D affects aortic valve (AV) remodeling. In this study, the influence of hyperinsulinemia and hyperglycemia on degenerative processes in valvular tissue is analyzed in intact AV exposed to an either static or dynamic 3D environment, respectively. The complex native dynamic environment of AV is simulated using a software-governed bioreactor system with controlled pulsatile flow. Dynamic cultivation resulted in significantly stronger fibrosis in AV tissue compared to static cultivation, while hyperinsulinemia and hyperglycemia had no impact on fibrosis. The expression of key differentiation markers and proteoglycans were altered by diabetic conditions in an environment-dependent manner. Furthermore, hyperinsulinemia and hyperglycemia affect insulin-signaling pathways. Western blot analysis showed increased phosphorylation level of protein kinase B (AKT) after acute insulin stimulation, which was lost in AV under hyperinsulinemia, indicating acquired insulin resistance of the AV tissue in response to elevated insulin levels. These data underline a complex interplay of diabetic conditions on one hand and biomechanical 3D environment on the other hand that possesses an impact on AV tissue remodeling.

TRPV1 Activation by Capsaicin Mediates Glucose Oxidation and ATP Production Independent of Insulin Signalling in Mouse Skeletal Muscle Cells

BACKGROUND

Insulin resistance (IR), a key characteristic of type 2 diabetes (T2DM), is manifested by decreased insulin-stimulated glucose transport in target tissues. Emerging research has highlighted transient receptor potential cation channel subfamily V member (TRPV1) activation by capsaicin as a potential therapeutic target for these conditions. However, there are limited data on the effects of capsaicin on cell signalling molecules involved in glucose uptake.

METHODS

C2C12 cells were cultured and differentiated to acquire the myotube phenotype. The activation status of signalling molecules involved in glucose metabolism, including 5' adenosine monophosphate-activated protein kinase (AMPK), calcium/calmodulin-dependent protein kinase 2 (CAMKK2), extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), protein kinase B (AKT), and src homology phosphatase 2 (SHP2), was examined. Finally, activation of CAMKK2 and AMPK, and glucose oxidation and ATP levels were measured in capsaicin-treated cells in the presence or absence of TRPV1 antagonist (SB-452533).

RESULTS

Capsaicin activated cell signalling molecules including CAMKK2 and AMPK leading to increased glucose oxidation and ATP generation independent of insulin in the differentiated C2C12 cells. Pharmacological inhibition of TRPV1 diminished the activation of CAMKK2 and AMPK as well as glucose oxidation and ATP production. Moreover, we observed an inhibitory effect of capsaicin in the phosphorylation of ERK1/2 in the mouse myotubes.

CONCLUSION

Our data show that capsaicin-mediated stimulation of TRPV1 in differentiated C2C12 cells leads to activation of CAMKK2 and AMPK, and increased glucose oxidation which is concomitant with an elevation in intracellular ATP level. Further studies of the effect of TRPV1 channel activation by capsaicin on glucose metabolism could provide novel therapeutic utility for the management of IR and T2DM.

FGF21 promotes thermogenic gene expression as an autocrine factor in adipocytes

The contribution of adipose-derived FGF21 to energy homeostasis is unclear. Here we show that browning of inguinal white adipose tissue (iWAT) by β-adrenergic agonists requires autocrine FGF21 signaling. Adipose-specific deletion of the FGF21 co-receptor β-Klotho renders mice unresponsive to β-adrenergic stimulation. In contrast, mice with liver-specific ablation of FGF21, which eliminates circulating FGF21, remain sensitive to β-adrenergic browning of iWAT. Concordantly, transgenic overexpression of FGF21 in adipocytes promotes browning in a β-Klotho-dependent manner without increasing circulating FGF21. Mechanistically, we show that β-adrenergic stimulation of thermogenic gene expression requires FGF21 in adipocytes to promote phosphorylation of phospholipase C-γ and mobilization of intracellular calcium. Moreover, we find that the β-adrenergic-dependent increase in circulating FGF21 occurs through an indirect mechanism in which fatty acids released by adipocyte lipolysis subsequently activate hepatic PPARα to increase FGF21 expression. These studies identify FGF21 as a cell-autonomous autocrine regulator of adipose tissue function.

Abu-Odeh et al. demonstrate that autocrine action of FGF21 is a required second signal promoting thermogenic gene expression in catecholamine-stimulated adipocytes. Hepatic FGF21 secretions, secondary to catecholamine-stimulated adipocyte lipolysis, are dispensable for adipose tissue browning. These studies identify FGF21 as a cell-autonomous autocrine regulator of adipose tissue function.

A Bioinformatics Investigation into the Pharmacological Mechanisms of Sodium-Glucose Co-transporter 2 Inhibitors in Diabetes Mellitus and Heart Failure Based on Network Pharmacology

PURPOSE

Diabetes mellitus (DM) is a major risk factor for the development of heart failure (HF). Sodium-glucose co-transporter 2 (SGLT2) inhibitors have demonstrated consistent benefits in the reduction of hospitalization for HF in patients with DM. However, the pharmacological mechanism is not clear. To investigate the mechanisms of SGLT2 inhibitors in DM with HF, we performed target prediction and network analysis by a network pharmacology method.

METHODS

We selected targets of SGLT2 inhibitors and DM status with HF from databases and studies. The "Drug-Target" and "Drug-Target-Disease" networks were constructed using Cytoscape. Then the protein-protein interaction (PPI) was analyzed using the STRING database. Gene Ontology (GO) biological functions and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were performed to investigate using the Bioconductor tool for analysis.

RESULTS

There were 125 effective targets between SGLT2 inhibitors and DM status with HF. Through further screening, 33 core targets were obtained, including SRC, MAPK1, NARS, MAPK3 and EGFR. It was predicted that the Rap1 signaling pathway, MAPK signaling pathway, EGFR tyrosine kinase inhibitor resistance, AGE-RAGE signaling pathway in diabetic complications and other signaling pathways were involved in the treatment of DM with HF by SGLT2 inhibitors.

CONCLUSION

Our study elucidated the possible mechanisms of SGLT2 inhibitors from a systemic and holistic perspective based on pharmacological networks. The key targets and pathways will provide new insights for further research on the pharmacological mechanism of SGLT2 inhibitors in the treatment of DM with HF.

FGF21 is required for the metabolic benefits of IKKε/TBK1 inhibition

The protein kinases IKKε and TBK1 are activated in liver and fat in mouse models of obesity. We have previously demonstrated that treatment with the IKKε/TBK1 inhibitor amlexanox produces weight loss and relieves insulin resistance in obese animals and patients. While amlexanox treatment caused a transient reduction in food intake, long-term weight loss was attributable to increased energy expenditure via FGF21-dependent beiging of white adipose tissue (WAT). Amlexanox increased FGF21 synthesis and secretion in several tissues. Interestingly, although hepatic secretion determined circulating levels, it was dispensable for regulating energy expenditure. In contrast, adipocyte-secreted FGF21 may have acted as an autocrine factor that led to adipose tissue browning and weight loss in obese mice. Moreover, increased energy expenditure was an important determinant of improved insulin sensitivity by amlexanox. Conversely, the immediate reductions in fasting blood glucose observed with acute amlexanox treatment were mediated by the suppression of hepatic glucose production via activation of STAT3 by adipocyte-secreted IL-6. These findings demonstrate that amlexanox improved metabolic health via FGF21 action in adipocytes to increase energy expenditure via WAT beiging and that adipocyte-derived IL-6 has an endocrine role in decreasing gluconeogenesis via hepatic STAT3 activation, thereby producing a coordinated improvement in metabolic parameters.

SGLT1 Inhibition Attenuates Apoptosis in Diabetic Cardiomyopathy via the JNK and p38 Pathway

Background: Recent studies have revealed that a novel selective sodium-glucose cotransporter 1 (SGLT1) inhibiton has shown beneficial effects in cardiovascular diseases. However, the question of whether SGLT1 inhibition influences diabetic cardiomyopathy (DCM) remains unanswered. In this study, we investigated the influence and underlying mechanism of SGLTI inhibition on DCM. Methods: SGLT1 levels were measured in diabetic patients with similar conditions who visited our hospital from January to December 2019. Wistar male rats (n = 50) were divided into five groups: control, diabetes induced by streptozotocin infusion, and diabetes treated with 0.5, 1.0, or 1.5 mg/kg mizagliflozin via stomach gavage for 12 weeks. H9C2 cardiomyocytes were treated with mizagliflozin and then exposed to a high glucose concentration (30 mmol/L). TUNEL assays were performed, and bcl2, bax, p-p38, p-Erk, p-JNK and caspase-3 levels were measured. We used siRNA and an SGLT1 overexpression plasmid to detect the effects of SGLT1. Results: SGLT1 levels were significantly elevated in DCM patients, and receiver operating characteristic (ROC) curve analysis identified SGLT1 as influencing DCM. The area under the curve (AUC) was 0.705 (p < 0.05), with 65.8% sensitivity, and 62.2% specificity. SGLT1 inhibition appeared to attenuate apoptosis in DCM via the JNK and p38 pathway. Conclusion: SGLT1 can be used as a marker for the diagnosis of DCM, and SGLT1 inhibition can attenuate apoptosis, thereby suppressing DCM development via the JNK and p38 pathway.

RPS4Y1 Promotes High Glucose-Induced Endothelial Cell Apoptosis and Inflammation by Activation of the p38 MAPK Signaling

AIM

Endothelial dysfunction is a key pathological basis for diabetes mellitus complications, including diabetic nephropathy, diabetic retinopathy, and diabetic cardiomyopathy. This study aimed to reveal the functional role of ribosomal protein S4 Y-linked 1 (RPS4Y1) in endothelial dysfunction.

METHODS

Human umbilical vein endothelial cells (HUVECs) were subjected to high glucose. The expression of RPS4Y1 in cells was overexpressed or silenced by plasmid or siRNA transfection. MTT assay, flow cytometry, JC-1 probe, scratch test, tube formation, and ELISA were conducted to assess the effects of RPS4Y1 on cell. Western blot was performed to assay the downstream signaling of RPS4Y1. The inhibitors of p38, ERK, and Jnk were used to treat cells to validate the involvement of them in RPS4Y1-mediated endothelial dysfunction.

RESULTS

RPS4Y1 was upregulated in HUVECs in response to high glucose in both dose- and time-dependent manners. Overexpression of RPS4Y1 induced viability loss, apoptosis, and inflammation, but inhibited cell migration and tube formation. Silence of RPS4Y1 impacted these aspects in a contrary trend. The phosphorylation of p38 rather than ERK and Jnk was activated by RPS4Y1. In addition, the dysfunction of HUVECs mediated by RPS4Y1 was attenuated by SB203580 (a specific inhibitor of p38 signaling).

CONCLUSION

The highly expressed RPS4Y1 in endothelial cells may contribute to high glucose-induced dysfunction through regulating p38 MAPK signaling. RPS4Y1 might be a potential therapeutic target for treating diabetes mellitus complications.

Galectin-3 mediates cardiac remodeling caused by impaired glucose and lipid metabolism through inhibiting two pathways of activating Akt

Pathological cardiac remodeling is a leading cause of mortality in patients with diabetes. Given the glucose and lipid metabolism disorders (GLDs) in patients with diabetes, it is urgent to conduct a comprehensive study of the myocardial damage under GLDs and find key mechanisms. Apolipoprotein E knockout (ApoE-/-) mice, low-density lipoprotein receptor heterozygote (Ldlr+/-) Syrian golden hamsters, or H9C2 cells were used to construct GLDs models. GLDs significantly promoted cardiomyocyte fibrosis, apoptosis, and hypertrophy in vivo and in vitro, but inhibition of galectin-3 (Gal-3) could significantly reverse this process. Then, the signal transmission pathways were determined. It was found that GLDs considerably inhibited the phosphorylation of Akt at Thr308/Ser473, whereas the silencing of Gal-3 could reverse the inhibition of Akt activity through phosphoinositide 3-kinase-AktThr308 (PI3K-AktThr308) and AMP-activated protein kinase-mammalian target of rapamycin complex 2-AktSer473 (AMPK-mTOR2-AktSer473) pathways. Finally, the PI3K, mTOR, AMPK inhibitor, and Akt activator were used to investigate the role of pathways in regulating cardiac remodeling. Phospho-AktThr308 could mediate myocardial fibrosis, whereas myocardial apoptosis and hypertrophy were regulated by both phospho-AktThr308 and phospho-AktSer473. In conclusion, Gal-3 was an important regulatory factor in GLDs-induced cardiac remodeling, and Gal-3 could suppress the phosphorylation of Akt at different sites in mediating cardiomyocyte fibrosis, apoptosis, and hypertrophy.NEW & NOTEWORTHY Studies on the pathogenesis of diabetic cardiac remodeling are highly desired. Glucose and lipid metabolism are both disordered in diabetes. Glucose and lipid metabolism disturbances promote myocardial fibrosis, apoptosis, and hypertrophy through galectin-3. Galectin-3 promotes cardiac remodeling by inhibiting phosphorylation of AktThr308 or AktSer473. The present study finds that glucose and lipid metabolism disorders are important causes for myocardial damage and provides novel ideas for the prevention and treatment of diabetic cardiac remodeling.

Molecular Insights into the MAPK Cascade during Viral Infection: Potential Crosstalk between HCQ and HCQ Analogues

The mitogen-activated protein kinase (MAPK) pathway links the cell-surface receptors to the transcription machinery, transducing the extracellular signals into several outputs, which may also adapt the host defense mechanism to viral attacks. The Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) that causes the COrona VIrus Disease 2019 (COVID-19) has infected upwards of nearly 70 million people and worldwide has claimed more than 1,600,000 deaths. So far, there continues to be no specific treatment for this novel coronavirus-induced disease. In the search to control the global COVID-19 pandemic, some eastern and developing countries have approved a variety of treatments with controversial efficacy, among which is the use of the antimalarial hydroxychloroquine (HCQ). Interestingly, prior data had indicated that the HCQ/CQ could influence the MAPK cascade. The main aim of this review is to address molecular mechanisms, beyond drugs, that can be helpful against viral infection for this and future pandemics. We will highlight (1) the contribution of the MAPK cascade in viral infection and (2) the possible use of MAPK inhibitors in curbing viral infections, alone or in combination with HCQ and quinoline analogues. We are convinced that understanding the molecular patterns of viral infections will be critical for new therapeutical approaches to control this and other severe diseases.

Role of AMP-activated protein kinase on cardio-metabolic abnormalities in the development of diabetic cardiomyopathy: A molecular landscape

Cardiovascular complications associated with diabetes mellitus remains a leading cause of morbidity and mortality across the world. Diabetic cardiomyopathy is a descriptive pathology that in absence of co-morbidities such as hypertension, dyslipidemia initially characterized by cardiac stiffness, myocardial fibrosis, ventricular hypertrophy, and remodeling. These abnormalities further contribute to diastolic dysfunctions followed by systolic dysfunctions and eventually results in clinical heart failure (HF). The clinical outcomes associated with HF are considerably worse in patients with diabetes. The complexity of the pathogenesis and clinical features of diabetic cardiomyopathy raises serious questions in developing a therapeutic strategy to manage cardio-metabolic abnormalities. Despite extensive research in the past decade the compelling approaches to manage and treat diabetic cardiomyopathy are limited. AMP-Activated Protein Kinase (AMPK), a serine-threonine kinase, often referred to as cellular "metabolic master switch". During the development and progression of diabetic cardiomyopathy, a plethora of evidence demonstrate the beneficial role of AMPK on cardio-metabolic abnormalities including altered substrate utilization, impaired cardiac insulin metabolic signaling, mitochondrial dysfunction and oxidative stress, myocardial inflammation, increased accumulation of advanced glycation end-products, impaired cardiac calcium handling, maladaptive activation of the renin-angiotensin-aldosterone system, endoplasmic reticulum stress, myocardial fibrosis, ventricular hypertrophy, cardiac apoptosis, and impaired autophagy. Therefore, in this review, we have summarized the findings from pre-clinical and clinical studies and provided a collective overview of the pathophysiological mechanism and the regulatory role of AMPK on cardio-metabolic abnormalities during the development of diabetic cardiomyopathy.

Bioinformatic Reconstruction and Analysis of Gene Networks Related to Glucose Variability in Diabetes and Its Complications

Glucose variability (GV) has been recognized recently as a promoter of complications and therapeutic targets in diabetes. The aim of this study was to reconstruct and analyze gene networks related to GV in diabetes and its complications. For network analysis, we used the ANDSystem that provides automatic network reconstruction and analysis based on text mining. The network of GV consisted of 37 genes/proteins associated with both hyperglycemia and hypoglycemia. Cardiovascular system, pancreas, adipose and muscle tissues, gastrointestinal tract, and kidney were recognized as the loci with the highest expression of GV-related genes. According to Gene Ontology enrichment analysis, these genes are associated with insulin secretion, glucose metabolism, glycogen biosynthesis, gluconeogenesis, MAPK and JAK-STAT cascades, protein kinase B signaling, cell proliferation, nitric oxide biosynthesis, etc. GV-related genes were found to occupy central positions in the networks of diabetes complications (cardiovascular disease, diabetic nephropathy, retinopathy, and neuropathy) and were associated with response to hypoxia. Gene prioritization analysis identified new gene candidates (THBS1, FN1, HSP90AA1, EGFR, MAPK1, STAT3, TP53, EGF, GSK3B, and PTEN) potentially involved in GV. The results expand the understanding of the molecular mechanisms of the GV phenomenon in diabetes and provide molecular markers and therapeutic targets for future research.

Cardioprotective effects of short-term empagliflozin treatment in db/db mice

Sodium glucose transporter (SGLT)-2 inhibitors have consistently shown cardioprotective effects independent of the glycemic status of treated patients. In this study we aimed to investigate underlying mechanisms of short-term empagliflozin treatment in a mouse model of type II diabetes. Male db/db mice were fed a western type diet with or without enrichment with empagliflozin for 7 days. While glucose tolerance was significantly improved in empagliflozin treated mice, body weight and fasting insulin levels were comparable in both groups. Cardiac insulin signaling activity indicated by reduced proteinkinase B (AKT) phosphorylation was significantly decreased in the empagliflozin treated group. Remarkably, mitochondrial mass estimated by citrate synthase activity was significantly elevated in empagliflozin treated mice. Accordingly, mitochondrial morphology was significantly altered upon treatment with empagliflozin as analysed by transmission electron microscopy. Additionally, short-term empagliflozin therapy was associated with a changed cardiac tissue cytokine expression in favor of an anti-inflammatory pattern. Our data suggest that early cardioprotection in empagliflozin treated mice is independent of a reduction in body weight or hyperinsulinemia. Ameliorated mitochondrial ultrastructure, attenuated cardiac insulin signaling and diminished cardiac inflammation might contribute to the cardioprotective effects of empagliflozin.

Effects of a fructose-rich diet and chronic stress on insulin signaling and regulation of glycogen synthase kinase-3 beta and the sodium-potassium pump in the hearts of male rats

Both a diet rich in fructose and chronic stress exposure induce metabolic and cardiovascular disturbances. The aim of this study was to examine the effects of the fructose-rich diet and chronic stress, separately and in combination, on insulin signaling and molecules regulating glycogen synthesis and ion transport in the heart, and to reveal whether these effects coincide with changes in glucocorticoid receptor (GR) activation. Male Wistar rats were subjected to 10% fructose in drinking water and/or to chronic unpredictable stress for 9 weeks. Protein expression and/or phosphorylation of the insulin receptor (IR), protein tyrosine phosphatase 1B, insulin receptor substrate 1 (IRS1), protein kinase B (Akt), extracellular signal-regulated kinase 1/2 (ERK1/2), glycogen synthase kinase-3β (GSK-3β) and Na+/K+-ATPase α-subunits in cardiac tissue were analyzed by western blot. GR distribution between cytosolic and nuclear fractions was also analyzed. The fructose-rich diet decreased the level of pERK1/2 (Thr202/Tyr204) and pGSK-3β (Ser9) independently of stress, while chronic stress increased the IRS1 content and prevented the fructose diet-induced decrease of the pAkt (Ser473) level. The fructose-rich diet in combination with chronic stress reduced the protein content of cardiac IR and attenuated IRS1 upregulation. Separate treatments increased the protein content of Na+/K+-ATPase α1- and α2-subunits, while after combined treatment the α2 content was at the control level and the α1 content was lower than the control level. The effect of combined treatment on cardiac IR and α2-subunit expression could be mediated by increased GR nuclear accumulation. Our study provides new insights into the effects of chronic stress and a combination of the fructose diet and chronic stress on the studied molecules in the heart.

Network Pharmacology-Based Strategy Reveals the Effects of Hedysarum multijugum Maxim.-Radix Salviae Compound on Oxidative Capacity and Cardiomyocyte Apoptosis in Rats with Diabetic Cardiomyopathy

Objective

To explore the effects of the Hedysarum multijugum Maxim.-Radix Salviae compound (Huangqi-Danshen Compound (HDC)) on oxidative capacity and cardiomyocyte apoptosis in rats with diabetic cardiomyopathy by a network pharmacology-based strategy.

Methods

Traditional Chinese Medicine (TCM)@Taiwan, TCM Systems Pharmacology Database and Analysis Platform (TCMSP), TCM Integrated Database (TCMID), and High-Performance Liquid Chromatography (HPLC) technology were used to obtain and screen HDC's active components, and the PharmMapper database was used to predict HDC human target protein targets. The DCM genes were collected from the GeneCards and OMIM databases, and the network was constructed and analyzed by Cytoscape 3.7.1 and the Database for Annotation, Visualization, and Integrated Discovery (DAVID). Finally, HDC was used to intervene in diabetic cardiomyopathy (DCM) model rats, and important biological processes and signaling pathways were verified using techniques such as immunohistochemistry.

Results

A total of 176 of HDC's active components and 442 potential targets were obtained. The results of network analysis show that HDC can regulate DCM-related biological processes (such as negative regulation of the apoptotic process, response to hypoxia, the steroid hormone-mediated signaling pathway, cellular iron ion homeostasis, and positive regulation of phosphatidylinositol 3-kinase signaling) and signaling pathways (such as the HIF-1 signaling pathway, the estrogen signaling pathway, insulin resistance, the PPAR signaling pathway, the VEGF signaling pathway, and the PI3K-Akt signaling pathway). Animal experiments show that HDC can reduce fasting plasma glucose (FPG), HbA1c, and malondialdehyde (MDA) and increase superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) (P < 0.05). The results of immunohistochemistry showed that HDC can regulate the protein expression of apoptosis-related signaling pathways in DCM rats (P < 0.05).

Conclusion

It was initially revealed that HDC improves DCM through its antiapoptotic and anti-inflammatory effects. HDC may play a therapeutic role by improving cardiomyocyte apoptosis in DCM rats.

Novel Anti-inflammatory Effects of Canagliflozin Involving Hexokinase II in Lipopolysaccharide-Stimulated Human Coronary Artery Endothelial Cells

Purpose

Vascular inflammation and disturbed metabolism are observed in heart failure and type 2 diabetes mellitus. Glycolytic enzyme hexokinase II (HKII) is upregulated by inflammation. We hypothesized that SGLT2 inhibitors Canagliflozin (Cana), Empagliflozin (Empa) or Dapagliflozin (Dapa) reduces inflammation via HKII in endothelial cells, and that HKII-dependent inflammation is determined by ERK1/2, NF-κB. and/or AMPK activity in lipopolysaccharide (LPS)-stimulated human coronary artery endothelial cells (HCAECs).

Methods

HCAECs were pre-incubated with 3 μM or 10 μM Cana, 1 μM, 3 μM or 10 μM Empa or 0.5 μM, 3 μM or 10 μM Dapa (16 h) and subjected to 3 h LPS (1 μg/mL). HKII was silenced via siRNA transfection. Interleukin-6 (IL-6) release was measured by ELISA. Protein levels of HK I and II, ERK1/2, AMPK and NF-κB were detected using infra-red western blot.

Results

LPS increased IL-6 release and ERK1/2 phosphorylation; Cana prevented these pro-inflammatory responses (IL-6: pg/ml, control 46 ± 2, LPS 280 ± 154 p < 0.01 vs. control, LPS + Cana 96 ± 40, p < 0.05 vs. LPS). Cana reduced HKII expression (HKII/GAPDH, control 0.91 ± 0.16, Cana 0.71 ± 0.13 p < 0.05 vs. control, LPS 1.02 ± 0.25, LPS + Cana 0.82 ± 0.24 p < 0.05 vs. LPS). Empa and Dapa were without effect on IL-6 release and HKII expression in the model used. Knockdown of HKII by 37% resulted caused partial loss of Cana-mediated IL-6 reduction (pg/ml, control 35 ± 5, LPS 188 ± 115 p < 0.05 vs. control, LPS + Cana 124 ± 75) and ERK1/2 activation by LPS. In LPS-stimulated HCAECs, Cana, but not Empa or Dapa, activated AMPK. AMPK activator A769662 reduced IL-6 release.

Conclusion

Cana conveys anti-inflammatory actions in LPS-treated HCAECs through 1) reductions in HKII and ERK1/2 phosphorylation and 2) AMPK activation. These data suggest a novel anti-inflammatory mechanism of Cana through HKII.

Electronic supplementary material

The online version of this article (10.1007/s10557-020-07083-w) contains supplementary material, which is available to authorized users.

SHP2 knockdown ameliorates liver insulin resistance by activating IRS-2 phosphorylation through the AKT and ERK1/2 signaling pathways

Diabetes is a chronic metabolic disease characterized by insulin resistance (IR). SHP2 has previously been identified as a potential target to reduce IR in diabetes. Here, we examined the effects of SHP2 on glucose consumption (GC), IR level and the expression of insulin receptor substrate (IRS), AKT and extracellular signal-regulated kinase (ERK)1/2 proteins in a cellular and animal model of diabetes. IR was induced in hepatocellular carcinoma (HCC) cells, and SHP2 was up-regulated or down-regulated in cells. Diabetic rats were treated with SHP2 inhibitor. GC of cells, and the weight, total cholesterol, triglycerides, fasting blood glucose, fasting insulin, homeostasis model assessment-IR index and insulin sensitivity (ISI) of the rats were analyzed. The levels of SHP2 and the activation of IRS-2, AKT and ERK1/2 in cells and rats were measured by quantitative real-time PCR (qRT-PCR) or western blot. GC was reduced, but expression of SHP2 was enhanced in IR HCC cells. Phosphorylation of IRS-2 and AKT in IR HCC cells and diabetic rats was decreased, whereas phosphorylation of ERK1/2 was enhanced. In both the cell and animal models, SHP2 knockdown enhanced GC, ameliorated IR, activated IRS-2 and AKT, and inhibited ERK1/2 phosphorylation, in contrast with the effects of SHP2 overexpression. SHP2 knockdown may enhance GC and ameliorate IR through phosphorylation of IRS-2 via regulating AKT and ERK1/2 in liver.

Heart failure and diabetes: role of ATM

Heart failure is a leading cause of death in the United States. Diabetes, also known as diabetes mellitus (DM), exponentially increases the risk of heart failure. The increase in oxidative stress and metabolic dysfunction caused by DM can lead to DNA damage and the development of diabetic cardiomyopathy. Ataxia telangiectasia mutated kinase (ATM) is a DNA damage response protein with a primary nuclear function to regulate cell cycle progression in response to double-strand DNA breaks, acts as a redox sensor, and facilitates DNA repair. ATM deficiency associates with the development of insulin resistance and DM. Consequently, patients with Ataxia telangiectasia, a rare autosomal recessive disorder, have an increased risk of developing heart failure. The main objective of this review is to summarize the shared metabolic and cardiac abnormalities associated with DM and ATM deficiency, with a focus on the development of heart failure.

Angiotensin-converting enzyme 2, the complement system, the kallikrein-kinin system, type-2 diabetes, interleukin-6, and their interactions regarding the complex COVID-19 pathophysiological crossroads

Because of the current COVID-19-pandemic, the world is currently being held hostage in various lockdowns. ACE2 facilitates SARS-CoV-2 cell-entry, and is at the very center of several pathophysiological pathways regarding the RAAS, CS, KKS, T2DM, and IL-6. Their interactions with severe COVID-19 complications (e.g. ARDS and thrombosis), and potential therapeutic targets for pharmacological intervention, will be reviewed.

Cardiomyocyte adhesion and hyperadhesion differentially require ERK1/2 and plakoglobin

Arrhythmogenic cardiomyopathy (AC) is a heart disease often caused by mutations in genes coding for desmosomal proteins, including desmoglein-2 (DSG2), plakoglobin (PG), and desmoplakin (DP). Therapy is based on symptoms and limiting arrhythmia, because the mechanisms by which desmosomal components control cardiomyocyte function are largely unknown. A new paradigm could be to stabilize desmosomal cardiomyocyte adhesion and hyperadhesion, which renders desmosomal adhesion independent from Ca²⁺. Here, we further characterized the mechanisms behind enhanced cardiomyocyte adhesion and hyperadhesion. Dissociation assays performed in HL-1 cells and murine ventricular cardiac slice cultures allowed us to define a set of signaling pathways regulating cardiomyocyte adhesion under basal and hyperadhesive conditions. Adrenergic signaling, activation of PKC, and inhibition of p38MAPK enhanced cardiomyocyte adhesion, referred to as positive adhesiotropy, and induced hyperadhesion. Activation of ERK1/2 paralleled positive adhesiotropy, whereas adrenergic signaling induced PG phosphorylation at S665 under both basal and hyperadhesive conditions. Adrenergic signaling and p38MAPK inhibition recruited DSG2 to cell junctions. In PG-deficient mice with an AC phenotype, only PKC activation and p38MAPK inhibition enhanced cardiomyocyte adhesion. Our results demonstrate that cardiomyocyte adhesion can be stabilized by different signaling mechanisms, which are in part offset in PG-deficient AC.

Desmosome mediated cardiomyocyte adhesion, crucial in the pathology of arrhythmogenic cardiomyopathy, is differentially regulated by multiple signaling mechanisms that depend either on ERK1/2 or plakoglobin.