Hyperglycemia suppresses cardiac stem cell homing to peri-infarcted myocardium via regulation of ERK1/2 and p38 MAPK activities

Cardioprotective role of A-cycloglycosylated derivative of Rubiadin in diabetic cardiomyopathy in rats

Diabetic cardiomyopathy (DCM) is a kind of idiopathic heart disease, which is one of the main complications of diabetes and seriously threatens the life of diabetic patients. Rubiadin, an anthraquinone compound extracted from the stems and roots of rubiaceae, has been widely discussed for its anti-diabetes, anti-oxidation and other pharmacological effects. However, Rubiadin can cause drug-induced liver injury. Therefore, A-cycloglycosylated derivative of Rubiadin (ACDR) was obtained by modifying its structure. The purpose of this study was to investigate the effect of ACDR on DCM cardiac injury and its mechanism. The DCM animal model was established by streptozotocin, and the success of DCM was verified by blood glucose level, echocardiographic evidence of impaired myocardial functions along with enhanced myocardial fibrosis. We performed liver function tests, morphological staining of the heart and tests for oxidative stress to evaluate cardiac functional and structural changes. Finally, the expression of Na⁺/H⁺ exchanger (NHE1) protein was analyzed by immunohistochemistry and western bolt, and the expression of hairy/enhancer-of-split related with YRPW motif 1 (Hey1) and P-p38 protein was detected by immunofluorescence chemistry and western blotting. The results showed that ACDR can improve cardiac dysfunction, reduce myocardial injury, reduce oxidative stress, and protect the liver in DCM rats. Interestingly, all variations were countered by LiCl. Our study suggests that, along with controlling hyperglycemia, ACDR may improve DCM by reducing NHE1 expression, further inhibiting P-p38 activity and increasing Hey1 expression to reduce oxidative stress.

Study of FOXO1-interacting proteins using TurboID-based proximity labeling technology

BACKGROUND

Protein‒protein interactions (PPIs) are the foundation of the life activities of cells. TurboID is a biotin ligase with higher catalytic efficiency than BioID or APEX that reduces the required labeling time from 18 h to 10 min. Since many proteins participate in binding and catalytic events that are very short-lived, it is theoretically possible to find relatively novel binding proteins using the TurboID technique. Cell proliferation, apoptosis, autophagy, oxidative stress and metabolic disorders underlie many diseases, and forkhead box transcription factor 1 (FOXO1) plays a key role in these physiological and pathological processes.

RESULTS

The FOXO1-TurboID fusion gene was transfected into U251 astrocytes, and a cell line stably expressing FOXO1 was constructed. While constructing the FOXO1 overexpression plasmid, we also added the gene sequence of TurboID to perform biotin labeling experiments in the successfully fabricated cell line to look for FOXO1 reciprocal proteins. Label-free mass spectrometry analysis was performed, and 325 interacting proteins were found. A total of 176 proteins were identified in the FOXO1 overexpression group, and 227 proteins were identified in the Lipopolysaccharide -treated group (Lipopolysaccharide, LPS). Wild-type U251 cells were used to exclude interference from nonspecific binding. The FOXO1-interacting proteins hnRNPK and RBM14 were selected for immunoprecipitation and immunofluorescence verification.

CONCLUSION

The TurboID technique was used to select the FOXO1-interacting proteins, and after removing the proteins identified in the blank group, a large number of interacting proteins were found in both positive groups. This study lays a foundation for further study of the function of FOXO1 and the regulatory network in which it is involved.

Diabetes-Induced Cellular Senescence and Senescence-Associated Secretory Phenotype Impair Cardiac Regeneration and Function Independently of Age

Diabetes mellitus (DM) affects the biology of multipotent cardiac stem/progenitor cells (CSCs) and adult myocardial regeneration. We assessed the hypothesis that senescence and senescence-associated secretory phenotype (SASP) are main mechanisms of cardiac degenerative defect in DM. Accordingly, we tested whether ablation of senescent CSCs would rescue the cardiac regenerative/reparative defect imposed by DM. We obtained cardiac tissue from nonaged (50- to 64-year-old) patients with type 2 diabetes mellitus (T2DM) and without DM (NDM) and postinfarct cardiomyopathy undergoing cardiac surgery. A higher reactive oxygen species production in T2DM was associated with an increased number of senescent/dysfunctional T2DM-human CSCs (hCSCs) with reduced proliferation, clonogenesis/spherogenesis, and myogenic differentiation versus NDM-hCSCs in vitro. T2DM-hCSCs showed a defined pathologic SASP. A combination of two senolytics, dasatinib (D) and quercetin (Q), cleared senescent T2DM-hCSCs in vitro, restoring their expansion and myogenic differentiation capacities. In a T2DM model in young mice, diabetic status per se (independently of ischemia and age) caused CSC senescence coupled with myocardial pathologic remodeling and cardiac dysfunction. D + Q treatment efficiently eliminated senescent cells, rescuing CSC function, which resulted in functional myocardial repair/regeneration, improving cardiac function in murine DM. In conclusion, DM hampers CSC biology, inhibiting CSCs' regenerative potential through the induction of cellular senescence and SASP independently from aging. Senolytics clear senescence, abrogating the SASP and restoring a fully proliferative/differentiation-competent hCSC pool in T2DM with normalization of cardiac function.

Unraveling and Targeting Myocardial Regeneration Deficit in Diabetes

Cardiomyopathy is a common complication in diabetic patients. Ventricular dysfunction without coronary atherosclerosis and hypertension is driven by hyperglycemia, hyperinsulinemia and impaired insulin signaling. Cardiomyocyte death, hypertrophy, fibrosis, and cell signaling defects underlie cardiomyopathy. Notably, detrimental effects of the diabetic milieu are not limited to cardiomyocytes and vascular cells. The diabetic heart acquires a senescent phenotype and also suffers from altered cellular homeostasis and the insufficient replacement of dying cells. Chronic inflammation, oxidative stress, and metabolic dysregulation damage the population of endogenous cardiac stem cells, which contribute to myocardial cell turnover and repair after injury. Therefore, deficient myocardial repair and the progressive senescence and dysfunction of stem cells in the diabetic heart can represent potential therapeutic targets. While our knowledge of the effects of diabetes on stem cells is growing, several strategies to preserve, activate or restore cardiac stem cell compartments await to be tested in diabetic cardiomyopathy.

The Fate Status of Stem Cells in Diabetes and its Role in the Occurrence of Diabetic Complications

Diabetes mellitus (DM) is becoming a growing risk factor for public health worldwide. It is a very common disease and is widely known for its susceptibility to multiple complications which do great harm to the life and health of patients, some even lead to death. To date, there are many mechanisms for the complications of diabetes, including the generation of reactive oxygen species (ROS) and the abnormal changes of gas transmitters, which ultimately lead to injuries of cells, tissues and organs. Normally, even if injured, the body can quickly repair and maintain its homeostasis. This is closely associated with the repair and regeneration ability of stem cells. However, many studies have demonstrated that stem cells happen to be damaged under DM, which may be a nonnegligible factor in the occurrence and progression of diabetic complications. Therefore, this review summarizes how diabetes causes the corresponding complications by affecting stem cells from two aspects: stem cells dysfunctions and stem cells quantity alteration. In addition, since mesenchymal stem cells (MSCs), especially bone marrow mesenchymal stem cells (BMMSCs), have the advantages of strong differentiation ability, large quantity and wide application, we mainly focus on the impact of diabetes on them. The review also puts forward the basis of using exogenous stem cells to treat diabetic complications. It is hoped that through this review, researchers can have a clearer understanding of the roles of stem cells in diabetic complications, thus promoting the process of using stem cells to treat diabetic complications.

Regenerative Medicine for the Treatment of Ischemic Heart Disease; Status and Future Perspectives

Cardiovascular disease is now the leading cause of adult death in the world. According to new estimates from the World Health Organization, myocardial infarction (MI) is responsible for four out of every five deaths due to cardiovascular disease. Conventional treatments of MI are taking aspirin and nitroglycerin as intermediate treatments and injecting antithrombotic agents within the first 3 h after MI. Coronary artery bypass grafting and percutaneous coronary intervention are the most common long term treatments. Since none of these interventions will fully regenerate the infarcted myocardium, there is value in pursuing more innovative therapeutic approaches. Regenerative medicine is an innovative interdisciplinary method for rebuilding, replacing, or repairing the missed part of different organs in the body, as similar as possible to the primary structure. In recent years, regenerative medicine has been widely utilized as a treatment for ischemic heart disease (one of the most fatal factors around the world) to repair the lost part of the heart by using stem cells. Here, the development of mesenchymal stem cells causes a breakthrough in the treatment of different cardiovascular diseases. They are easily obtainable from different sources, and expanded and enriched easily, with no need for immunosuppressing agents before transplantation, and fewer possibilities of genetic abnormality accompany them through multiple passages. The production of new cardiomyocytes can result from the transplantation of different types of stem cells. Accordingly, due to its remarkable benefits, stem cell therapy has received attention in recent years as it provides a drug-free and surgical treatment for patients and encourages a more safe and feasible cardiac repair. Although different clinical trials have reported on the promising benefits of stem cell therapy, there is still uncertainty about its mechanism of action. It is important to conduct different preclinical and clinical studies to explore the exact mechanism of action of the cells. After reviewing the pathophysiology of MI, this study addresses the role of tissue regeneration using various materials, including different types of stem cells. It proves some appropriate data about the importance of ethical problems, which leads to future perspectives on this scientific method.

Targeting Cardiac Stem Cell Senescence to Treat Cardiac Aging and Disease

Adult stem/progenitor are a small population of cells that reside in tissue-specific niches and possess the potential to differentiate in all cell types of the organ in which they operate. Adult stem cells are implicated with the homeostasis, regeneration, and aging of all tissues. Tissue-specific adult stem cell senescence has emerged as an attractive theory for the decline in mammalian tissue and organ function during aging. Cardiac aging, in particular, manifests as functional tissue degeneration that leads to heart failure. Adult cardiac stem/progenitor cell (CSC) senescence has been accordingly associated with physiological and pathological processes encompassing both non-age and age-related decline in cardiac tissue repair and organ dysfunction and disease. Senescence is a highly active and dynamic cell process with a first classical hallmark represented by its replicative limit, which is the establishment of a stable growth arrest over time that is mainly secondary to DNA damage and reactive oxygen species (ROS) accumulation elicited by different intrinsic stimuli (like metabolism), as well as external stimuli and age. Replicative senescence is mainly executed by telomere shortening, the activation of the p53/p16^INK4/Rb molecular pathways, and chromatin remodeling. In addition, senescent cells produce and secrete a complex mixture of molecules, commonly known as the senescence-associated secretory phenotype (SASP), that regulate most of their non-cell-autonomous effects. In this review, we discuss the molecular and cellular mechanisms regulating different characteristics of the senescence phenotype and their consequences for adult CSCs in particular. Because senescent cells contribute to the outcome of a variety of cardiac diseases, including age-related and unrelated cardiac diseases like diabetic cardiomyopathy and anthracycline cardiotoxicity, therapies that target senescent cell clearance are actively being explored. Moreover, the further understanding of the reversibility of the senescence phenotype will help to develop novel rational therapeutic strategies.

ZHX2 drives cell growth and migration via activating MEK/ERK signal and induces Sunitinib resistance by regulating the autophagy in clear cell Renal Cell Carcinoma

Zinc fingers and homeoboxes 2 (ZHX2) was found as a novel VHL substrate target, and acted as an oncogenic driver in ccRCC. However, the detailed mechanism of ZHX2 in ccRCC development remains elusive, and no research has focused on studying ZHX2 in drug resistance yet. A tissue microarray with 358 ccRCC samples was used to determine the expression of ZHX2 in ccRCC patients. VHL-deficient cell line 786-O and VHL-normal cell line CAKI-1 was used for lineage reprogramming by transfecting with lentivirus. The in vitro and in vivo experiments were performed with these new cell lines to determine the mechanism of ZHX2 in ccRCC development and drug resistance. Immunohistochemistry analysis showed that ZHX2 was not highly expressed in ccRCC tumor tissues, only 33.2% (119/358) patients have high ZHX2 expression. However, high ZHX2 was significantly associated with advanced Fuhrman grade (p = 0.004), and proved to be an independent prognosis factor for progression-free survival (p = 0.0003), while there is no significant correlation with overall survival. We further discovered that ZHX2 overexpression could increase VEGF secretion and transcriptional activate the MEK/ERK1/2 and promote its downstream targets. We also found ZHX2 overexpression induce Sunitinib resistance though activating autophagy and the combination treatment of Sunitinib and Chloroquine could significantly rescue the phenomenon. In summary, these results indicate that ZHX2 drivers cell growth, migration though increase VEGF expression, and transcriptional activate MEK/ERK1/2 signaling pathway, and could induce Sunitinib resistance by regulating self-protective autophagy, these may provide new insight in advanced ccRCC treatment.

Stem Cell Homing: a Potential Therapeutic Strategy Unproven for Treatment of Myocardial Injury

Despite advances in the prevention and therapeutic modalities of ischemic heart disease, morbidity and mortality post-infarction heart failure remain big challenges in modern society. Stem cell therapy is emerging as a promising therapeutic strategy. Stem cell homing, the ability of stem cells to find their destination, is receiving more attention. Identification of specific cues and understanding the signaling pathways that direct stem cells to targeted destination will improve stem cell homing efficiency. This review discusses the cellular and molecular mechanism of stem cell homing at length in the light of literature and analyzes the problem and considerations of this approach as a treatment strategy for the treatment of ischemic heart disease clinically.

Cytoprotective Roles of a Novel Compound, MHY-1684, against Hyperglycemia-Induced Oxidative Stress and Mitochondrial Dysfunction in Human Cardiac Progenitor Cells

Diabetic cardiomyopathy (DCM) is tightly linked to heart disorders and dysfunction or death of the cardiomyocytes including resident cardiac progenitor cells (CPCs) in diabetic patients. In order to restore loss of function of resident or transplanted CPCs, much research has focused on novel therapeutic strategies including the discovery of novel function-modulating factors such as reactive oxygen species (ROS) scavengers. Here, we developed and defined a novel antioxidant, MHY-1684, for enhancing the angiogenic potential of CPCs against ROS-related DCM. Short-term treatment with MHY-1684 restored ROS-induced CPC cell death. Importantly, MHY-1684 decreased hyperglycemia-induced mitochondrial ROS generation and attenuated hyperglycemia-induced mitochondrial fragmentation. We observed that the activation process of both Drp1 (phosphorylation at the site of Ser616) and Fis-1 is drastically attenuated when exposed to high concentrations of D-glucose with MHY-1684. Interestingly, phosphorylation of Drp1 at the site of Ser637, which is an inhibitory signal for mitochondrial fusion, is restored by MHY-1684 treatment, suggesting that this antioxidant may affect the activation and inhibition of mitochondrial dynamics-related signaling and mitochondrial function in response to ROS stress. In conclusion, our finding of the novel compound, MHY-1684, as an ROS scavenger, might provide an effective therapeutic strategy for CPC-based therapy against diabetic cardiomyopathy.

Inhibition of MEK/ERK/STAT3 signaling in oleuropein treatment inhibits myocardial ischemia/reperfusion

Studies have shown that oleuropein has antifungal, anti‑inflammatory, antiviral, antioxidant, anticancer and hypoglycemic functions. TTC solution staining was used to measure myocardial infarction size. A commercial kit was used to measure lactate dehydrogenase (LDH), creatinine kinase‑MB (CK‑MB), tumor necrosis factor‑α (TNF‑α), interleukin‑1β (IL‑1β), IL 6, superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) and catalase levels. Western blot analysis was used to measure p53, p-MEK p-ERK and p‑IκBα protein expression. The present study reports that the protective effect of oleuropein also prevents against myocardial ischemia/reperfusion (myocardial I/R). The aim of this retrospective study was to evaluate this protective effect of oleuropein and the mechanisms by which myocardial I/R is prevented. Oleuropein inhibited myocardial infarction size, CK‑MB and LDH serum levels in a myocardial I/R rat model. Moreover, oleuropein also attenuated caspase‑3 activity, and p53, phosphorylated (p)‑mitogen‑activated protein kinase kinase (MEK), p‑extracellular signal‑regulated protein kinase (ERK) and p‑IκBα protein expression. TNF‑α, IL‑1β, IL‑6 and MDA were decreased; SOD, GSH and catalase levels inhibited TNF‑α, IL‑1β, IL-6 and MDA levels, and increased SOD, GSH and catalase levels in myocardial I/R rats treated with oleuropein. Rats orally administered the MEK inhibitor PD0325901, in addition to oleuropein, exhibited inhibited myocardial infarction size, CK‑MB and LDH serum levels compared with rats treated with oleuropein only. Rats treated with MEK inhibitor also exhibited suppressed caspase‑3 activity, p53, p‑MEK p‑ERK and p‑IκBα protein expression, TNF‑α, IL‑1β, IL‑6, SOD, GSH, MDA and catalase levels, and induced p‑signal transducer and activator of transcription 3 (STAT3) protein expression compared with rats treated with oleuropein only. Taken together, these results suggest that MEK/ERK/STAT3 signaling regulates the inhibition of myocardial I/R in rats treated with oleuropein.

Concise Review: Challenges in Regenerating the Diabetic Heart: A Comprehensive Review

Stem cell therapy is one of the promising regenerative strategies developed to improve cardiac function in patients with ischemic heart diseases (IHD). However, this approach is limited in IHD patients with diabetes due to a progressive decline in the regenerative capacity of stem cells. This decline is mainly attributed to the metabolic memory incurred by diabetes on stem cell niche and their systemic cues. Understanding the molecular pathways involved in the diabetes-induced deterioration of stem cell function will be critical for developing new cardiac regeneration therapies. In this review, we first discuss the most common molecular alterations occurring in the diabetic stem cells/progenitor cells. Next, we highlight the key signaling pathways that can be dysregulated in a diabetic environment and impair the mobilization of stem/progenitor cells, which is essential for the transplanted/endogenous stem cells to reach the site of injury. We further discuss the possible methods of preconditioning the diabetic cardiac progenitor cell (CPC) with an aim to enrich the availability of efficient stem cells to regenerate the diseased diabetic heart. Finally, we propose new modalities for enriching the diabetic CPC through genetic or tissue engineering that would aid in developing autologous therapeutic strategies, improving the proliferative, angiogenic, and cardiogenic properties of diabetic stem/progenitor cells. Stem Cells 2017;35:2009-2026.

SCF increases cardiac stem cell migration through PI3K/AKT and MMP‑2/‑9 signaling

The transplantation of cardiac stem cells (CSCs) is thought to be responsible for improving the performance of injured heart induced by myocardial infarction (MI). However, the mechanisms involved in the migration of activated CSCs post-MI remain to be clarified. In this study, CSCs were isolated from rat hearts and a cellular migration assay was performed using a 24-well Transwell system. Stem cell factor (SCF) induced CSC migration in a concentration-dependent manner, which could be blocked with an SCF antibody as well as a PI3K/AKT inhibitor, LY294002. Moreover, SCF induced the expression and activity of matrix metalloproteinase (MMP)-2 and MMP-9 in a concentration- and time-dependent manner, as measured by quantitative RT-PCR, western blot analysis and gelatin zymography. Results of western blot analysis revealed phosphorylated AKT was markedly increased in SCF-treated CSCs and that inhibition of SCF/c-Kit signaling or phospho-AKT activity significantly attenuated the SCF-induced expression of MMP-2 and MMP-9. Thus, our results showed that SCF partially mediated CSC migration via the activation of PI3K/AKT/MMP-2/-9 signaling.

Cardiac regeneration and diabetes

The prevalence of diabetes continues to increase world-wide and is a leading cause of morbidity, mortality, and rapidly rising health care costs. Although strict glucose control combined with good pharmacological and non-pharmacologic interventions can increase diabetic patient life span, the frequency and mortality of myocardial ischemia and infarction remain drastically increased in diabetic patients. Therefore, more effective therapeutic approaches are urgently needed. Over the past 15 years, cellular repair of the injured adult heart has become the focus of a rapidly expanding broad spectrum of pre-clinical and clinical research. Recent clinical trials have achieved favorable initial endpoints with improvements in cardiac function and clinical symptoms following cellular therapy. Due to the increased risk of cardiac disease, cardiac regeneration may be one strategy to treat patients with diabetic cardiomyopathy and/or myocardial infarction. However, pre-clinical studies suggest that the diabetic myocardium may not be a favorable environment for the transplantation and survival of stem cells due to altered kinetics in cellular homing, survival, and in situ remodeling. Therefore, unique conditions in the diabetic myocardium will require novel solutions in order to increase the efficiency of cellular repair following ischemia and/or infarction. This review briefly summarizes some of the recent advances in cardiac regeneration in non-diabetic conditions and then provides an overview of some of the issues related to diabetes that must be addressed in the coming years.