PPARs: regulators of metabolism and as therapeutic targets in cardiovascular disease. Part II: PPAR-β/δ and PPAR-γ (original) (raw)
Related papers
Current Opinion in Pharmacology, 2005
Several conditions and risk factors predispose to cardiovascular disease, including visceral obesity, type 2 diabetes, insulin resistance, hypertension and dyslipidemia, and are collectively called the metabolic syndrome. Different pharmacological approaches are under development to address these risk factors and improve the cardiovascular risk profile. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that control lipid and glucose metabolism, as well as the inflammatory response. Thus PPARs appear good drug targets for the correction of the global risk profile that predisposes an individual to cardiovascular disease.
Endocrine, Metabolic & Immune Disorders - Drug Targets, 2011
The association between metabolic syndrome and cardiovascular diseases raises important questions about the underlying pathological processes, especially for designing targeted therapeutic interventions. The Peroxisome Proliferators Activated Receptors (PPARs) are ligand-activated transcription factors that control lipid and glucose metabolism. Accumulating data suggest that PPARs may serve as potential targets for treating metabolic diseases and their cardiovascular complications. PPARs regulate gene expression by binding with RXR as a heterodimeric partner to specific DNA sequences, termed PPAR response elements. In addition, PPARs may modulate gene transcription also by directly interfering with other transcription factor pathways in a DNA-binding independent manner. To date, three different PPAR isoforms, designated α, β/δ and γ, have been identified. PPARα and PPARγ are the most extensively examined and characterized, mainly because they are activated by compounds, such as fibrates and thiazolidinediones, that are in clinical use for the treatment of hypertriglyceridemia and insulin resistance, respectively. In contrast the role of PPARβ/δ in metabolism has been less investigated. The recent availability of specific PPARβ/δ agonists revealed that PPARβ/δ plays a crucial role in fatty acid metabolism in several tissues. Besides, PPARβ/δ activation exerts beneficial effects against organ-related ischemic events, such as myocardial and cerebral infarction, which are among the most critical cardiovascular complications evoked by metabolic dysregulation. This paper reviews the evidence and recent developments relating to the potential therapeutic effects of PPARβ/δ agonists in the treatment of metabolic syndrome and its associated cardiovascular risk factors.
PPARγ signaling and metabolism: the good, the bad and the future
Nature Medicine, 2013
Thiazolidinediones (TZDs) are potent insulin sensitizers that act through the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ) and are highly effective oral medications for type 2 diabetes. However, their unique benefits are shadowed by the risk for fluid retention, weight gain, bone loss and congestive heart failure. This raises the question as to whether it is possible to build a safer generation of PPARγ-specific drugs that evoke fewer side effects while preserving insulin-sensitizing potential. Recent studies that have supported the continuing physiologic and therapeutic relevance of the PPARγ pathway also provide opportunities to develop newer classes of molecules that reduce or eliminate adverse effects. This review highlights key advances in understanding PPARγ signaling in energy homeostasis and metabolic disease and also provides new explanations for adverse events linked to TZD-based therapy. The PPARs are members of the nuclear receptor superfamily of ligand-inducible transcription factors 1. In mammals, there are three PPARs: PPARα (also called NR1C1), PPARβ/δ (also called NR1C2) and PPARγ (also called NR1C3). By binding to PPARresponsive regulatory elements as obligate heterodimers with retinoid X receptor (RXR), the PPARs control the expression of networks of genes involved in adipogenesis, lipid metabolism, inflammation and maintenance of metabolic homeostasis 2. Similar to typical nuclear receptors, PPARs are comprised of distinct functional domains, including an Nterminal transactivation domain (AF1), a highly conserved DNA-binding domain (DBD) and a C-terminal ligand-binding domain (LBD) containing a ligand-dependent transactivation function (AF2) 3. These domains are all potential targets for modulation of the PPAR signaling cascades. Although they are known as receptors for common dietary fats such as oleic, linoleic and linolenic acids, PPARs also bind and respond to diverse lipid metabolites, including prostaglandin J2, 8S-hydroxyeicosatetraenoic acid and a collection of oxidized phospholipids 4-6. Ligand binding induces a conformational change in the receptor that allows for differential recruitment of cofactors and subsequent modulation of PPAR activity 3 .
PPARβ/δ: A Key Therapeutic Target in Metabolic Disorders
International journal of molecular sciences, 2018
Research in recent years on peroxisome proliferator-activated receptor (PPAR)β/δ indicates that it plays a key role in the maintenance of energy homeostasis, both at the cellular level and within the organism as a whole. PPARβ/δ activation might help prevent the development of metabolic disorders, including obesity, dyslipidaemia, type 2 diabetes mellitus and non-alcoholic fatty liver disease. This review highlights research findings on the PPARβ/δ regulation of energy metabolism and the development of diseases related to altered cellular and body metabolism. It also describes the potential of the pharmacological activation of PPARβ/δ as a treatment for human metabolic disorders.
PPAR Agonists and Metabolic Syndrome: An Established Role?
International Journal of Molecular Sciences, 2018
Therapeutic approaches to metabolic syndrome (MetS) are numerous and may target lipoproteins, blood pressure or anthropometric indices. Peroxisome proliferator-activated receptors (PPARs) are involved in the metabolic regulation of lipid and lipoprotein levels, i.e., triglycerides (TGs), blood glucose, and abdominal adiposity. PPARs may be classified into the α, β/δ and γ subtypes. The PPAR-α agonists, mainly fibrates (including newer molecules such as pemafibrate) and omega-3 fatty acids, are powerful TG-lowering agents. They mainly affect TG catabolism and, particularly with fibrates, raise the levels of high-density lipoprotein cholesterol (HDL-C). PPAR-γ agonists, mainly glitazones, show a smaller activity on TGs but are powerful glucose-lowering agents. Newer PPAR-α/δ agonists, e.g., elafibranor, have been designed to achieve single drugs with TG-lowering and HDL-C-raising effects, in addition to the insulin-sensitizing and antihyperglycemic effects of glitazones. They also hold promise for the treatment of non-alcoholic fatty liver disease (NAFLD) which is closely associated with the MetS. The PPAR system thus offers an important hope in the management of atherogenic dyslipidemias, although concerns regarding potential adverse events such as the rise of plasma creatinine, gallstone formation, drug-drug interactions (i.e., gemfibrozil) and myopathy should also be acknowledged.
International journal of molecular sciences, 2018
Peroxisome proliferator-activated receptor-delta (PPAR-δ), one of three members of the PPAR group in the nuclear receptor superfamily, is a ligand-activated transcription factor. PPAR-δ regulates important cellular metabolic functions that contribute to maintaining energy balance. PPAR-δ is especially important in regulating fatty acid uptake, transport, and β-oxidation as well as insulin secretion and sensitivity. These salutary PPAR-δ functions in normal cells are thought to protect against metabolic-syndrome-related diseases, such as obesity, dyslipidemia, insulin resistance/type 2 diabetes, hepatosteatosis, and atherosclerosis. Given the high clinical burden these diseases pose, highly selective synthetic activating ligands of PPAR-δ were developed as potential preventive/therapeutic agents. Some of these compounds showed some efficacy in clinical trials focused on metabolic-syndrome-related conditions. However, the clinical development of PPAR-δ agonists was halted because vari...
PPARs: Transcription Factors Controlling Lipid and Lipoprotein Metabolism
Annals of the New York Academy of Sciences, 2006
Nuclear receptors are transcription factors that are activated by ligands and subsequently bind to regulatory regions in target genes, thereby modulating their expression. Nuclear receptors thus allow the organism to integrate signals coming from the environment and to adapt by modifying the expression levels of relevant genes. The peroxisome proliferator-activated receptors (PPARs) ␣, /␦, and ␥ constitute a subfamily of nuclear receptors.
The Role of PPARγ in Cardiovascular Diseases
Physiological Research, 2016
The peroxisome proliferator-activated receptors (PPAR) belong to the nuclear superfamily of ligand-activated transcription factors. PPARγ acts as a nutrient sensor that regulates several homeostatic functions. Its disruption can lead to vascular pathologies, disorders of fatty acid/lipid metabolism and insulin resistance. PPARγ can modulate several signaling pathways connected with blood pressure regulation. Firstly, it affects the insulin signaling pathway and endothelial dysfunction by modulation of expression and/or phosphorylation of signaling molecules through the PI3K/Akt/eNOS or MAPK/ET-1 pathways. Secondly, it can modulate gene expression of the reninangiotensin system-cascade proteins, which potentially slow down the progression of atherosclerosis and hypertension. Thirdly, it can modulate oxidative stress response either directly through PPAR or indirectly through Nrf2 activation. In this context, activation and functioning of PPARγ is very important in the regulation of several disorders such as diabetes mellitus, hypertension and/or metabolic syndrome.