Transcriptional Control of Vascular Smooth Muscle Cell Proliferation by Peroxisome Proliferator-Activated Receptor-γ: Therapeutic Implications for Cardiovascular Diseases

Proliferation of vascular smooth muscle cells (SMCs) is a critical process for the development of atherosclerosis and complications of procedures used to treat atherosclerotic diseases, including postangioplasty restenosis, vein graft failure, and transplant vasculopathy. Peroxisome proliferator-activated receptor (PPAR) γ is a member of the nuclear hormone receptor superfamily and the molecular target for the thiazolidinediones (TZD), used clinically to treat insulin resistance in patients with type 2 diabetes. In addition to their efficacy to improve insulin sensitivity, TZD exert a broad spectrum of pleiotropic beneficial effects on vascular gene expression programs. In SMCs, PPARγ is prominently upregulated during neointima formation and suppresses the proliferative response to injury of the arterial wall. Among the molecular target genes regulated by PPARγ in SMCs are genes encoding proteins involved in the regulation of cell-cycle progression, cellular senescence, and apoptosis. This inhibition of SMC proliferation is likely to contribute to the prevention of atherosclerosis and postangioplasty restenosis observed in animal models and proof-of-concept clinical studies. This review will summarize the transcriptional target genes regulated by PPARγ in SMCs and outline the therapeutic implications of PPARγ activation for the treatment and prevention of atherosclerosis and its complications

Telomerase Inhibition by Everolimus Suppresses Smooth Muscle Cell Proliferation and Neointima Formation Through Epigenetic Gene Silencing

Proliferation of smooth muscle cells (SMCs) during neointima formation is prevented by drug-eluting stents. The replicative capacity of mammalian cells is enhanced by telomerase expression; however, the contribution of telomerase to the proliferative response underlying neointima formation and its potential role as a pharmacological target are unknown. The present study investigated the mechanisms underlying the mitogenic function of telomerase, and tested the hypothesis that everolimus, which is commonly used on drug-eluting stents, suppresses SMC proliferation by targeting telomerase. Inhibition of neointima formation by everolimus was lost in mice overexpressing telomerase reverse transcriptase (TERT), indicating that repression of telomerase confers the anti-proliferative efficacy of everolimus. Everolimus reduced TERT expression in SMC through an Ets-1-dependent inhibition of promoter activation. The inhibition of TERT-dependent SMC proliferation by everolimus occurred in the absence of telomere shortening but rather as a result of a G1→S-phase arrest. Although everolimus failed to inhibit phosphorylation of the retinoblastoma protein as the gatekeeper of S-phase entry, it potently repressed downstream target genes. Chromatin immunoprecipitation assays demonstrated that TERT induced E2F binding to S-phase gene promoters and supported histone acetylation. These effects were sensitive to inhibition by everolimus. These results characterize telomerase as a previously unrecognized target for the antiproliferative activity of everolimus, and further identify a novel mitogenic pathway in SMC that depends on the epigenetic activation of S-phase gene promoters by TERT

Oxidative Stress Accumulates in Adipose Tissue during Aging and Inhibits Adipogenesis

Aging constitutes a major independent risk factor for the development of type 2 diabetes and is accompanied by insulin resistance and adipose tissue dysfunction. One of the most important factors implicitly linked to aging and age-related chronic diseases is the accumulation of oxidative stress. However, the effect of increased oxidative stress on adipose tissue biology remains elusive. In this study, we demonstrate that aging in mice results in a loss of fat mass and the accumulation of oxidative stress in adipose tissue. In vitro, increased oxidative stress through glutathione depletion inhibits preadipocyte differentiation. This inhibition of adipogenesis is at least in part the result of reduced cell proliferation and an inhibition of G1→S-phase transition during the initial mitotic clonal expansion of the adipocyte differentiation process. While phosphorylation of the retinoblastoma protein (Rb) by cyclin/cdk complexes remains unaffected, oxidative stress decreases the expression of S-phase genes downstream of Rb. This silencing of S phase gene expression by increased oxidative stress is mediated through a transcriptional mechanism involving the inhibition of E2F recruitment and transactivation of its target promoters. Collectively, these data demonstrate a previously unrecognized role of oxidative stress in the regulation of adipogenesis which may contribute to age-associated adipose tissue dysfunction

Osteopontin Mediates Obesity-Induced Adipose Tissue Macrophage Infiltration and Insulin Resistance in Mice

Obesity is associated with a state of chronic, low-grade inflammation characterized by abnormal cytokine production and macrophage infiltration into adipose tissue, which may contribute to the development of insulin resistance. During immune responses, tissue infiltration by macrophages is dependent on the expression of osteopontin, an extracellular matrix protein and proinflammatory cytokine that promotes monocyte chemotaxis and cell motility. In the present study, we used a murine model of diet-induced obesity to examine the role of osteopontin in the accumulation of adipose tissue macrophages and the development of insulin resistance during obesity. Mice exposed to a high-fat diet exhibited increased plasma osteopontin levels, with elevated expression in macrophages recruited into adipose tissue. Obese mice lacking osteopontin displayed improved insulin sensitivity in the absence of an effect on diet-induced obesity, body composition, or energy expenditure. These mice further demonstrated decreased macrophage infiltration into adipose tissue, which may reflect both impaired macrophage motility and attenuated monocyte recruitment by stromal vascular cells. Finally, obese osteopontin-deficient mice exhibited decreased markers of inflammation, both in adipose tissue and systemically. Taken together, these results suggest that osteopontin may play a key role in linking obesity to the development of insulin resistance by promoting inflammation and the accumulation of macrophages in adipose tissue

mTOR-Dependent Oxidative Stress Regulates oxLDL-Induced Trained Innate Immunity in Human Monocytes

Introduction: Cells of the innate immune system particularly monocytes and macrophages have been recognized as pivotal players both during the initial insult as well as the chronic phase of atherosclerosis. It has recently been shown that oxidized low-density lipoprotein (oxLDL) induces a long-term pro-inflammatory response in monocytes due to epigenetic and metabolic reprogramming, an emerging new concept called trained innate immunity. Changes in the cellular redox state are crucial events in the regulation of many physiologic functions in macrophages including transcription, differentiation and inflammatory response. Here we have analyzed the role of reactive oxygen species (ROS) in regulating this proinflammatory monocyte priming in response to oxLDL-treatment.Methods and Results: Human monocytes were isolated and incubated with oxLDL for 24 h. After 5 days of resting, oxLDL treated cells produced significantly more inflammatory cytokines upon restimulation with the TLR2-agonist Pam3cys. Furthermore, oxLDL incubation induced persistent mTOR activation, ROS formation, HIF1α accumulation and HIF1α target gene expression, while pharmacologic mTOR inhibition or siRNA mediated inhibition of the mTORC1 subunit Raptor prevented ROS formation and proinflammatory priming. mTOR dependent ROS formation was associated with increased expression of NAPDH oxidases and necessary for the emergence of the primed phenotype as antioxidant treatment blocked oxLDL priming. Inhibition of cytosolic ROS formation could also block mTOR activation and HIF1α accumulation suggesting a positive feedback loop between mTOR and cytosolic ROS. Although mitochondrial ROS scavenging did not block HIF1α-accumulation at an early time point (24 h), it was persistently reduced on day 6. Therefore, mitochondrial ROS formation appears to occur initially downstream of the mTOR-cytoROS-HIF1α feedback loop but seems to be a crucial factor that controls the long-term activation of the mTOR-HIF1α-axis.Conclusion: In summary, our data demonstrate that mTOR dependent ROS production controls the oxLDL-induced trained innate immunity phenotype in human monocyte derived macrophages. Pharmacologic modulation of these pathways might provide a potential approach to modulate inflammation, associated with aberrant monocyte activation, during atherosclerosis development

Telomerase Deficiency Predisposes to Heart Failure and Ischemia-Reperfusion Injury

Introduction: Elevated levels of mitochondrial reactive oxygen species (ROS) contribute to the development of numerous cardiovascular diseases. TERT, the catalytic subunit of telomerase, has been shown to translocate to mitochondria to suppress ROS while promoting ATP production. Acute overexpression of TERT increases survival and decreases infarct size in a mouse model of myocardial infarct, while decreased telomerase activity predisposes to mitochondrial defects and heart failure. In the present study, we examined the role of TERT on cardiac structure and function under basal conditions and conditions of acute or prolonged stress in a novel rat model of TERT deficiency.Methods: Cardiac structure and function were evaluated via transthoracic echocardiogram. Langendorff preparations were used to test the effects of acute global ischemia reperfusion injury on cardiac function and infarction. Coronary flow and left ventricular pressure were measured during and after ischemia/reperfusion (I/R). Mitochondrial DNA integrity was measured by PCR and mitochondrial respiration was assessed in isolated mitochondria using an Oxygraph. Angiotensin II infusion was used as an established model of systemic stress.Results: No structural changes (echocardiogram) or coronary flow/left ventricle pressure (isolated hearts) were observed in TERT−/− rats at baseline; however, after I/R, coronary flow was significantly reduced in TERT−/− compared to wild type (WT) rats, while diastolic Left Ventricle Pressure was significantly elevated (n = 6 in each group; p < 0.05) in the TERT−/−. Interestingly, infarct size was less in TERT−/− rats compared to WT rats, while mitochondrial respiratory control index decreased and mitochondrial DNA lesions increased in TERT−/− compared to WT. Angiotensin II treatment did not alter cardiac structure or function; however, it augmented the infarct size significantly more in TERT−/− compared to the WT.Conclusion: Absence of TERT activity increases susceptibility to stress like cardiac injury. These results suggest a critical role of telomerase in chronic heart disease

Substantiation of efficiency of managerial solutions in enterprise competitiveness management (based on the materials of LLC “Polisan” Pro- duction Company)

Кваліфікаційна робота ступеня бакалавр напряму підготовки 0306 Менеджмент, НТУ «Дніпровська політехніка», Дніпро, 2020. Об’єкт розроблення – процес управління конкурентоспроможністю підприємства. Мета кваліфікаційної роботи – обґрунтування теоретичних, методичних основ і прикладних аспектів управління конкурентоспроможністю підприємства і розробка заходів щодо її підвищення. Основні результати кваліфікаційної роботи бакалавра полягають у такому: досліджено теоретично-методологічні основи управління конкурентоспроможністю підприємства; проаналізовано господарську діяльність ТОВ «ВП «Полісан»; виконано конкурентний аналіз сил ринку лакофарбових матеріалів в Україні; оцінено конкурентну позицію підприємства; досліджено ризики діяльності виробників лакофарбової продукції; виконано оцінку значущості впливу факторів внутрішніх ризиків на конкурентоспроможність підприємства; розроблено заходи щодо підвищення конкурентоспроможності підприємства та обґрунтовано їх ефективністьКваліфікаційна робота ступеня бакалавр напряму підготовки 0306 Менеджмент, НТУ «Дніпровська політехніка», Дніпро, 2020. Об’єкт розроблення – процес управління конкурентоспроможністю підприємства. Мета кваліфікаційної роботи – обґрунтування теоретичних, методичних основ і прикладних аспектів управління конкурентоспроможністю підприємства і розробка заходів щодо її підвищення. Основні результати кваліфікаційної роботи бакалавра полягають у такому: досліджено теоретично-методологічні основи управління конкурентоспроможністю підприємства; проаналізовано господарську діяльність ТОВ «ВП «Полісан»; виконано конкурентний аналіз сил ринку лакофарбових матеріалів в Україні; оцінено конкурентну позицію підприємства; досліджено ризики діяльності виробників лакофарбової продукції; виконано оцінку значущості впливу факторів внутрішніх ризиків на конкурентоспроможність підприємства; розроблено заходи щодо підвищення конкурентоспроможності підприємства та обґрунтовано їх ефективніст