8avb
From Proteopedia
Cryo-EM structure for mouse leptin in complex with the mouse LEP-R ectodomain (1:2 mLEP:mLEPR model)
Structural highlights
DiseaseLEP_MOUSE Defects in Lep are the cause of profound obesity and type II diabetes. FunctionLEP_MOUSE Key player in the regulation of energy balance and body weight control. Once released into the circulation, has central and peripheral effects by binding LEPR, found in many tissues, which results in the activation of several major signaling pathways (PubMed:15899045, PubMed:16825198, PubMed:11373681, PubMed:12594516, PubMed:20620997). In the hypothalamus, acts as an appetite-regulating factor that induces a decrease in food intake and an increase in energy consumption by inducing anorexinogenic factors and suppressing orexigenic neuropeptides, also regulates bone mass and secretion of hypothalamo-pituitary-adrenal hormones. In the periphery, increases basal metabolism, influences reproductive function, regulates pancreatic beta-cell function and insulin secretion, is pro-angiogenic for endothelial cell and affects innate and adaptive immunity (By similarity) (PubMed:8589726, PubMed:10660043, PubMed:25383904, PubMed:25060689, PubMed:9732873, PubMed:12594516). In the arcuate nucleus of the hypothalamus, activates by depolarization POMC neurons inducing FOS and SOCS3 expression to release anorexigenic peptides and inhibits by hyperpolarization NPY neurons inducing SOCS3 with a consequent reduction on release of orexigenic peptides (By similarity) (PubMed:20620997, PubMed:11373681). In addition to its known satiety inducing effect, has a modulatory role in nutrient absorption. In the intestine, reduces glucose absorption by enterocytes by activating PKC and leading to a sequential activation of p38, PI3K and ERK signaling pathways which exerts an inhibitory effect on glucose absorption. Acts as a growth factor on certain tissues, through the activation of different signaling pathways increases expression of genes involved in cell cycle regulation such as CCND1, via JAK2-STAT3 pathway, or VEGFA, via MAPK1/3 and PI3K-AKT1 pathways (By similarity) (PubMed:16825198, PubMed:20620997). May also play an apoptotic role via JAK2-STAT3 pathway and up-regulation of BIRC5 expression (By similarity). Pro-angiogenic, has mitogenic activity on vascular endothelial cells and plays a role in matrix remodeling by regulating the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) (PubMed:16825198). In innate immunity, modulates the activity and function of neutrophils by increasing chemotaxis and the secretion of oxygen radicals. Increases phagocytosis by macrophages and enhances secretion of pro-inflammatory mediators. Increases cytotoxic ability of NK cells (Probable). Plays a pro-inflammatory role, in synergy with IL1B, by inducing NOS2 wich promotes the production of IL6, IL8 and Prostaglandin E2, through a signaling pathway that involves JAK2, PI3K, MAP2K1/MEK1 and MAPK14/p38 (PubMed:15899045). In adaptive immunity, promotes the switch of memory T-cells towards T helper-1 cell immune responses (By similarity). Increases CD4(+)CD25(-) T cells proliferation and reduces autophagy during TCR (T cell receptor) stimulation, through MTOR signaling pathway activation and BCL2 up-regulation (PubMed:25060689).[UniProtKB:P41159][UniProtKB:P50596][1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Publication Abstract from PubMedThe adipokine Leptin activates its receptor LEP-R in the hypothalamus to regulate body weight and exerts additional pleiotropic functions in immunity, fertility and cancer. However, the structure and mechanism of Leptin-mediated LEP-R assemblies has remained unclear. Intriguingly, the signaling-competent isoform of LEP-R is only lowly abundant amid several inactive short LEP-R isoforms contributing to a mechanistic conundrum. Here we show by X-ray crystallography and cryo-EM that, in contrast to long-standing paradigms, Leptin induces type I cytokine receptor assemblies featuring 3:3 stoichiometry and demonstrate such Leptin-induced trimerization of LEP-R on living cells via single-molecule microscopy. In mediating these assemblies, Leptin undergoes drastic restructuring that activates its site III for binding to the Ig domain of an adjacent LEP-R. These interactions are abolished by mutations linked to obesity. Collectively, our study provides the structural and mechanistic framework for how evolutionarily conserved Leptin:LEP-R assemblies with 3:3 stoichiometry can engage distinct LEP-R isoforms to achieve signaling. Mechanism of receptor assembly via the pleiotropic adipokine Leptin.,Tsirigotaki A, Dansercoer A, Verschueren KHG, Markovic I, Pollmann C, Hafer M, Felix J, Birck C, Van Putte W, Catteeuw D, Tavernier J, Fernando Bazan J, Piehler J, Savvides SN, Verstraete K Nat Struct Mol Biol. 2023 Mar 23. doi: 10.1038/s41594-023-00941-9. PMID:36959263[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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