دانلود مقاله دوبل فارسی و انگلیسی گیرنده های فعال proliferator فعال و لیگاندهای آنها
| دسته بندی | پزشکی |
| فرمت فایل | |
| حجم فایل | 803 کیلو بایت |
| تعداد صفحات فایل | 19 |
فهرست مقاله:
چکیده
مقدمه
ساختار و عملکرد گیرنده های فعال کننده تکثیر پراکسی زومی
انواع گیرنده های فعال کننده تکثیر پراکسی زومی و بیان بافتی آن ها
لیگاند های PPAR
نقش عملکردی گیرنده های فعال کننده تکثیر پراکسی زومی
آگونیست های طبیعی گیرنده های فعال کننده تکثیر پراکسی زومی
آگونیست های سنتتیک
نقش کارکردی PPARβ/δ
آگونیست های PPARβ/δ
نقش بالینی و تغذیه ای PPARγ
آگونیست های طبیعی PPARγ2
آگونیست های فارماکولوژیکی PPARy
آگونیست دوگانه PPARα/γ
نتیجه گیری
|
بخشی از ترجمه فارسی مقاله: مقدمه انواع گیرنده های فعال کننده تکثیر پراکسی زومی و بیان بافتی آن ها |
|
بخشی از مقاله انگلیسی: Introduction Peroxisome proliferator-activated receptors are ligandactivated transcription factors that regulate genes important in cell differentiation and various metabolic processes, especially lipid and glucose homeostasis. In molecular terms, PPARs represent a family of ligand-activated nuclear hormone receptors (NRs) belonging to the steroid receptor superfamily [1,2] (Figure 1). Examples of NRs include the receptors for thyroid hormones, retinoids, 1,25- dihydroxy-vitamin D3, steroid hormone receptors and a variety of other ligands. After interaction with the specific ligands, nuclear receptors are translocated to the nucleus, where they change their structure and regulate gene transcription [3-5]. PPAR structure and function The three-dimensional structure of PPARs consists of a DNA binding domain in the N-terminus and a ligand binding domain (LBD) in the C-terminus. After interaction with agonists, PPARs are translocated to the nucleus and heterodimerize with another nuclear receptor – the retinoid X receptor (RXR) (Figure 2). The RXR forms a heterodimer with a number of other receptors (e.g., vitamin D or thyroid hormones). The specific DNA regions of target genes that bind with PPARs are termed peroxisome proliferator hormone response elements (PPREs) [1]. The PPREs are found in the promoters of PPAR responsive genes, such as the fatty acid-binding protein (aP2) [5]. In most cases, this process activates transcription of various genes involved in diverse physiological and pathophysiological processes. The function of PPARs is modified by a number of coactivators and corepressors, the presence of which can either stimulate or inhibit receptor function, respectively [6]. Ligands that activate PPARγ-RXR cause an exchange of co-repressors for co-activators [7,8]. Human cells are characterized by a different availability of cofactors that depends on the type of cell and the association of specific cofactors to other genes [7,9,10]. Types of PPARs and their tissue expression The family of peroxisome proliferation-activated receptors comprises three isoforms: PPARα, PPARβ/δ and PPARγ [1]. These three isotypes differ from each other in terms of their tissue distributions, ligand specificities and physiological roles. Each of them either activates or suppresses different genes with only partial overlap in activity (Figure 3) [5]. All isoforms participate in lipid homeostasis and glucose regulation (energy balance), and, until recently, their actions were thought to be limited to specific tissue types (Figure 4) [5,11]. PPARα is highly expressed in metabolically active tissues, such as liver, heart, skeletal muscle, intestinal mucosa and brown adipose tissue. This receptor is implicated in fatty acid metabolism and its activation lowers lipid levels [12-15]. PPARγ is expressed in white and brown adipose tissue, the large intestine and spleen. However, its expression is highest in adipocytes and it plays a key role in the regulation of adipogenesis, energy balance, and lipid biosynthesis [14,16-18]. This receptor also participates in lipoprotein metabolism and insulin sensitivity. The least known isoform is PPARβ/δ, which has not been so intensely studied as PPARα and PPARγ. PPARβ/δ is expressed ubiquitously in virtually all tissues; however, it is particularly abundant in the liver, intestine, kidney, abdominal adipose tissue, and skeletal muscle, all of which are involved in lipid metabolism. It participates in fatty acid oxidation, mainly in skeletal and cardiac muscles, regulates blood cholesterol concentrations and glucose levels [1,13,19,20]. In conclusion, PPARα and PPARβ/δ mainly facilitate energy combustion, whereas PPARγ contributes to energy storage by enhancing adipogenesis [21]. |