RA Mediated T-reg Differentiation: Difference between revisions
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==Introduction== | ==Introduction== | ||
T-regulatory cells (T-regs) are a small subset of CD4+ T-cells that exhibit strong down regulation of immune system activity in their local environment. They are distinguished from other CD4+ T-cells by the expression of FOXP3, a gene regulator. <ref> PMID: 19410687 </ref> The exact mechanisms used by T-regs to down regulate the immune system has not yet been clearly elucidated. These cells have been shown to differentiate from CD4+ T-helper cells upon activation and exposure to the following cytokines: tumor growth factor β (TGF-β), Interleukin-2 (IL-2) and retinoic acid (RA). <ref> PMID: 21839265 </ref> Both TGF-β and IL-2 are used in other immune system differentiation, however, RA has been shown to bias T-cells to the T-reg phenotype. <ref> PMID: 21839265 </ref> When acting upon T-reg cells, RA acts as the ligand for the Retinoic Acid Receptor-α (RARα) / Retinoid X Receptor-α (RXRα) heterodimer. This heterodimer is of the nuclear receptor family, and each chain consists of the same three part structure: a Ligand binding domain (LBD), a DNA binding domain (DBD), and a hinge region connecting the two binding domains. <ref> PMID: 10406480 </ref> | T-regulatory cells (T-regs) are a small subset of CD4+ T-cells that exhibit strong down regulation of immune system activity in their local environment. They are distinguished from other CD4+ T-cells by the expression of FOXP3, a gene regulator. <ref> PMID: 19410687 </ref> The exact mechanisms used by T-regs to down regulate the immune system has not yet been clearly elucidated. These cells have been shown to differentiate from CD4+ T-helper cells upon activation and exposure to the following cytokines: tumor growth factor β (TGF-β), Interleukin-2 (IL-2) and retinoic acid (RA). <ref> PMID: 21839265 </ref> Both TGF-β and IL-2 are used in other immune system differentiation, however, RA has been shown to bias T-cells to the T-reg phenotype. <ref> PMID: 21839265 </ref> When acting upon T-reg cells, RA acts as the ligand for the Retinoic Acid Receptor-α (RARα) / Retinoid X Receptor-α (RXRα) heterodimer. This heterodimer is of the nuclear receptor family, and each chain consists of the same three part structure: a Ligand binding domain (LBD), a DNA binding domain (DBD), and a hinge region connecting the two binding domains. <ref> PMID: 10406480 </ref> | ||
==Ligand Binding Domain== | ==Ligand Binding Domain== | ||
<scene name='51/519788/Cv/1'>RARα-RXRα interaction</scene> (PDB entry [[1dkf]]). | |||
The Ligand binding domain for each piece of the dimer has a nearly identical structure of an <scene name='RA_Mediated_T-reg_Differentiaition/Alpha-helical_domains/2'>Tα-helical sandwich</scene>. These alpha helices form a total of 12 domains per protein (referred to as H1-12), with an additional 2 beta sheets as well. Additionally, the α-helical sandwich formed has been shown to bind All-Trans Retinoic Acid (ATRA), the isomer of RA used by the body. Both monomers contain two regions of activity, the <scene name='RA_Mediated_T-reg_Differentiaition/Dimerization_interface/3'>dimerization interface</scene> and the <scene name='RA_Mediated_T-reg_Differentiaition/Ligand_binding_pockets/1'> ligand binding pocket </scene>.<ref> PMID: 10882070 </ref> | The Ligand binding domain for each piece of the dimer has a nearly identical structure of an <scene name='RA_Mediated_T-reg_Differentiaition/Alpha-helical_domains/2'>Tα-helical sandwich</scene>. These alpha helices form a total of 12 domains per protein (referred to as H1-12), with an additional 2 beta sheets as well. Additionally, the α-helical sandwich formed has been shown to bind All-Trans Retinoic Acid (ATRA), the isomer of RA used by the body. Both monomers contain two regions of activity, the <scene name='RA_Mediated_T-reg_Differentiaition/Dimerization_interface/3'>dimerization interface</scene> and the <scene name='RA_Mediated_T-reg_Differentiaition/Ligand_binding_pockets/1'> ligand binding pocket </scene>.<ref> PMID: 10882070 </ref> | ||