Sirt1 inhibits HG-induced endothelial injury: Role of Mff-based mitochondrial fission and F‑actin homeostasis-mediated cellular migration

Hyperglycemic Neurovasculature-On-A-Chip to Study the Effect of SIRT1-Targeted Therapy for the Type 3 Diabetes "Alzheimer's Disease"

Diabetes mellitus (DM) is closely related to Alzheimer's disease (AD), but individual cellular changes and the possibilities of recovery through molecular level regulation have not been investigated. Here, a neurovasculature-on-a-chip (NV chip) model is presented in which the perfusable brain microvasculature is surrounded by the neurons. Under hyperglycemic conditions, the brain microvasculature shows disruption of barrier function and reduced expression of junctional markers. The neurons show Tau pathology and amyloid-beta (Aß) accumulation. Endothelial cells and neurons in the NV chip show sirtuin 1 (SIRT1) downregulation under hyperglycemic conditions, suggesting SIRT1 as a key regulator of hyperglycemia-induced AD. The recovery of glucose levels rescue SIRT1 expression, suggesting that this type of intervention may rescue the progression of hyperglycemia-mediated AD. Furthermore, the short hairpin RNA (shRNA)-, clustered regularly interspaced short palindromic repeats (CRISPR)-, and pharmaceutics-mediated regulation of SIRT1 regulate the pathophysiology of the brain endothelium and neurons at the functional and molecular levels.

Expression and mechanism of microRNA 195 in diabetic retinopathy

We aimed to explore the role of microRNA 195 (miR-195) in diabetic retinopathy (DR). From January 2019 to July 2020, 50 patients with DR undergoing vitrectomy and 40 patients with idiopathic macular holes undergoing vitrectomy were selected as the observation group (OG) and control group (CG), respectively. The mRNA and protein expression levels of miR-195, SIRT1, BAX, and BCL-2 were detected in the retinal tissues obtained from the two groups during surgery. In addition, human retinal endothelial cells and human dermal microvascular endothelial cells were cultured in a high-glucose environment to detect the targeted relationship between miR-195 and SIRT1; determine the mRNA and protein expression levels of SIRT1, BAX, and BCL-2 after miR-195 knockdown; and assess the levels of cell proliferation and apoptosis. In OG, the mRNA and protein expression levels of miR-195 and BAX were high, whereas those of BCL-2 and SIRT1 were low. Moreover, we detected a targeted relationship between miR-195 and SIRT1. Conversely, miR-195 knockdown led to the downregulation of the mRNA and protein expression levels of BAX and the upregulation of the mRNA and protein expression levels of SIRT1 and BCL-2 as well as improvement in cell growth and a decrease in the apoptosis rate. miR-195 is overexpressed in DR, and its targeted relationship with SIRT1 inhibits the growth of cells in the retina and accelerates apoptosis.

The Emerging Role of HDACs: Pathology and Therapeutic Targets in Diabetes Mellitus

Diabetes mellitus (DM) is one of the principal manifestations of metabolic syndrome and its prevalence with modern lifestyle is increasing incessantly. Chronic hyperglycemia can induce several vascular complications that were referred to be the major cause of morbidity and mortality in DM. Although several therapeutic targets have been identified and accessed clinically, the imminent risk of DM and its prevalence are still ascending. Substantial pieces of evidence revealed that histone deacetylase (HDAC) isoforms can regulate various molecular activities in DM via epigenetic and post-translational regulation of several transcription factors. To date, 18 HDAC isoforms have been identified in mammals that were categorized into four different classes. Classes I, II, and IV are regarded as classical HDACs, which operate through a Zn-based mechanism. In contrast, class III HDACs or Sirtuins depend on nicotinamide adenine dinucleotide (NAD⁺) for their molecular activity. Functionally, most of the HDAC isoforms can regulate β cell fate, insulin release, insulin expression and signaling, and glucose metabolism. Moreover, the roles of HDAC members have been implicated in the regulation of oxidative stress, inflammation, apoptosis, fibrosis, and other pathological events, which substantially contribute to diabetes-related vascular dysfunctions. Therefore, HDACs could serve as the potential therapeutic target in DM towards developing novel intervention strategies. This review sheds light on the emerging role of HDACs/isoforms in diabetic pathophysiology and emphasized the scope of their targeting in DM for constituting novel interventional strategies for metabolic disorders/complications.

Mitochondrial network remodeling: an important feature of myogenesis and skeletal muscle regeneration

The remodeling of the mitochondrial network is a critical process in maintaining cellular homeostasis and is intimately related to mitochondrial function. The interplay between the formation of new mitochondria (biogenesis) and the removal of damaged mitochondria (mitophagy) provide a means for the repopulation of the mitochondrial network. Additionally, mitochondrial fission and fusion serve as a bridge between biogenesis and mitophagy. In recent years, the importance of these processes has been characterised in multiple tissue- and cell-types, and under various conditions. In skeletal muscle, the robust remodeling of the mitochondrial network is observed, particularly after injury where large portions of the tissue/cell structures are damaged. The significance of mitochondrial remodeling in regulating skeletal muscle regeneration has been widely studied, with alterations in mitochondrial remodeling processes leading to incomplete regeneration and impaired skeletal muscle function. Needless to say, important questions related to mitochondrial remodeling and skeletal muscle regeneration still remain unanswered and require further investigation. Therefore, this review will discuss the known molecular mechanisms of mitochondrial network remodeling, as well as integrate these mechanisms and discuss their relevance in myogenesis and regenerating skeletal muscle.

Pro-Senescence and Anti-Senescence Mechanisms of Cardiovascular Aging: Cardiac MicroRNA Regulation of Longevity Drug-Induced Autophagy

Chronological aging as well as biological aging accelerated by various pathologies such as diabetes and obesity contribute to cardiovascular aging, and structural and functional tissue damage of the heart and vasculature. Cardiovascular aging in humans is characterized by structural pathologic remodeling including cardiac and vascular fibrosis, hypertrophy, stiffness, micro- and macro-circulatory impairment, left ventricular diastolic dysfunction precipitating heart failure with either reduced or preserved ejection fraction, and cardiovascular cell death. Cellular senescence, an important hallmark of aging, is a critical factor that impairs repair and regeneration of damaged cells in cardiovascular tissues whereas autophagy, an intracellular catabolic process is an essential inherent mechanism that removes senescent cells throughout life time in all tissues. Several recent reviews have highlighted the fact that all longevity treatment paradigms to mitigate progression of aging-related pathologies converge in induction of autophagy, activation of AMP kinase (AMPK) and Sirtuin pathway, and inhibition of mechanistic target of rapamycin (mTOR). These longevity treatments include health style changes such as caloric restriction, and drug treatments using rapamycin, the first FDA-approved longevity drug, as well as other experimental longevity drugs such as metformin, rapamycin, aspirin, and resveratrol. However, in the heart tissue, autophagy induction has to be tightly regulated since evidence show excessive autophagy results in cardiomyopathy and heart failure. Here we discuss emerging evidence for microRNA-mediated tight regulation of autophagy in the heart in response to treatment with rapamycin, and novel approaches to monitor autophagy progression in a temporal manner to diagnose and regulate autophagy induction by longevity treatments.

C1q/TNF-related protein 5 contributes to diabetic vascular endothelium dysfunction through promoting Nox-1 signaling

OBJECTIVE

Dysregulated adipokine profiles contribute to the pathogenesis of diabetic cardiovascular complications. Endothelial cell (EC) dysfunction, a common pathological alteration in cardiovascular disorders, is exaggerated in diabetes. However, it is unclear whether and how dysregulated adipokines may contribute to diabetic EC dysfunction.

METHODS AND RESULTS

Serum C1q/TNF-Related Protein 5 (CTRP5) were determined in control/diabetes patients, and control/diabetic mice (high-fat diet, HFD). We observed for the first time that serum total CTRP5 was increased, high molecular weight (HMW) form was decreased, but the globular form (gCTRP5) was significantly increased in diabetic patients. These pathological alterations were reproduced in diabetic mice. To determine the pathological significance of increased gCTRP5 in diabetes, in vivo, ex vivo and in vitro experiments were performed. Diabetic atherosclerosis and EC dysfunction were significantly attenuated by the in vivo administration of CTRP5 neutralization antibody (CTRP5Ab). EC apoptosis was significantly increased in diabetic EC (isolated from HFD animal aorta) or high glucose high lipid (HGHL) cultured HUVECs. These pathological alterations were further potentiated by gCTRP5 and attenuated by CTRP5Ab. Pathway specific discovery-driven approach revealed that Nox1 expression was one of the signaling molecules commonly activated by HFD, HGHL, and gCTRP5. Treatment with CTRP5Ab reversed HFD-induced Nox1 upregulation. Finally, Nox1siRNA was used to determine the causative role of Nox1 in gCTRP5 induced EC apoptosis in diabetes. Results showed that gCTRP5 activated the mitochondrial apoptotic signal of EC in diabetes, which was blocked by the silencing Nox1 gene.

CONCLUSION

We demonstrated for the first time that gCTRP5 is a novel molecule contributing to diabetic vascular EC dysfunction through Nox1-mediated mitochondrial apoptosis, suggesting that interventions blocking gCTRP5 may protect diabetic EC function, ultimately attenuate diabetic cardiovascular complications.

Use of Human Umbilical Vein Endothelial Cells (HUVEC) as a Model to Study Cardiovascular Disease: A Review

Cardiovascular disease (CVD) is the leading cause of death worldwide, and extensive research has been performed to understand this disease better, using various experimental models. The endothelium plays a crucial role in the development of CVD, since it is an interface between bloodstream components, such as monocytes and platelets, and other arterial wall components. Human umbilical vein endothelial cell (HUVEC) isolation from umbilical cord was first described in 1973. To date, this model is still widely used because of the high HUVEC isolation success rate, and because HUVEC are an excellent model to study a broad array of diseases, including cardiovascular and metabolic diseases. We here review the history of HUVEC isolation, the HUVEC model over time, HUVEC culture characteristics and conditions, advantages and disadvantages of this model and finally, its applications in the area of cardiovascular diseases.