The Experts below are selected from a list of 24126 Experts worldwide ranked by ideXlab platform
Dudley K Strickland - One of the best experts on this subject based on the ideXlab platform.
-
LRP1 and sorl1 regulate tau internalization and degradation and enhance tau seeding
bioRxiv, 2020Co-Authors: Joanna M Cooper, Allison L Arai, Selen C Muratoglu, Aurelien Lathuiliere, Molly Migliorini, Mashhood Wani, Simon Dujardin, B T Hyman, Dudley K StricklandAbstract:ABSTRACT The identification of the apoE receptor, LRP1, as an endocytic receptor for tau raises several questions about LRP1s’ role in tauopathies. Is internalized tau, like other LRP1 ligands, delivered to lysosomes for degradation? Does LRP1 internalize pathological tau leading to cytosolic seeding? Do other, related receptors participate in these processes? We confirm that LRP1 rapidly internalizes tau, leading to efficient lysosomal degradation. Employing brain homogenates from human Alzheimer brain, we find that LRP1 also mediates cytosolic tau seeding. We additionally found that another apoE receptor, SORL1, a gene implicated in AD risk, also mediates tau endocytosis, degradation, and release into the cytoplasm of seed competent species. These data suggest a role for these apoE receptors in tau uptake, as well as the competing processes of degradation and release to the cytoplasm. The balance of these processes may be fundamental to spread of neuropathology across the brain in Alzheimer disease.
-
high affinity binding of ldl receptor related protein 1 to matrix metalloprotease 1 requires protease inhibitor complex formation
Biochemistry, 2020Co-Authors: Allison L Arai, Mary Migliorini, Elizabeth Hahndantona, David Peeney, William G Stetlerstevenson, Selen Muratoglu, Dudley K StricklandAbstract:Matrix metalloprotease (MMP) activation contributes to the degradation of the extracellular matrix (ECM), resulting in a multitude of pathologies. Low-density lipoprotein receptor-related protein 1 (LRP1) is a multifaceted endocytic and signaling receptor that is responsible for internalization and lysosomal degradation of diverse proteases, protease inhibitors, and lipoproteins along with numerous other proteins. In this study, we identified MMP-1 as a novel LRP1 ligand. Binding studies employing surface plasmon resonance revealed that both proMMP-1 and active MMP-1 bind to purified LRP1 with equilibrium dissociation constants (KD) of 19 and 25 nM, respectively. We observed that human aortic smooth muscle cells readily internalize and degrade 125I-labeled proMMP-1 in an LRP1-mediated process. Our binding data also revealed that all tissue inhibitors of metalloproteases (TIMPs) bind to LRP1 with KD values ranging from 23 to 33 nM. Interestingly, the MMP-1/TIMP-1 complex bound to LRP1 with an affinity (KD = 0.6 nM) that was 30-fold higher than that of either component alone, revealing that LRP1 prefers the protease:inhibitor complex as a ligand. Of note, modification of lysine residues on either proMMP-1 or TIMP-1 ablated the ability of the MMP-1/TIMP-1 complex to bind to LRP1. LRP1's preferential binding to enzyme:inhibitor complexes was further supported by the higher binding affinity for proMMP-9/TIMP-1 complexes than for either of these two components alone. LRP1 has four clusters of ligand-binding repeats, and MMP-1, TIMP-1, and MMP-1/TIMP-1 complexes bound to cluster III most avidly. Our results reveal an important role for LRP1 in controlling ECM homeostasis by regulating MMP-1 and MMP-9 levels.
-
high affinity binding of plasminogen activator inhibitor 1 complexes to ldl receptor related protein 1 requires lysines 80 88 and 207
Journal of Biological Chemistry, 2020Co-Authors: Mary Migliorini, Daniel A Lawrence, Shihhon Li, Anqi Zhou, Cory D Emal, Dudley K StricklandAbstract:: It is well established that complexes of plasminogen-activator inhibitor 1 (PAI-1) with its target enzymes bind tightly to LDL receptor-related protein 1 (LRP1), but the molecular details of this interaction are not well defined. Further, considerable controversy exists in the literature regarding the nature of the interaction of free PAI-1 with LRP1. In this study, we examined the binding of free PAI-1 and complexes of PAI-1 with low-molecular-weight urokinase-type plasminogen activator (LMWuPA) to LRP1. Our results confirmed that uPA:PAI-1 complexes bind LRP1 with ~100-fold increased affinity over PAI-1 alone. Chemical modification of PAI-1 confirmed an essential requirement of lysine residues in PAI-1 for the interactions of both PAI-1 and uPA:PAI-1 complexes with LRP1. Results of surface plasmon resonance measurements supported a bivalent binding model in which multiple sites on PAI-1 and uPA:PAI-1 complexes interact with complementary sites on LRP1. An ionic-strength dependence of binding suggested the critical involvement of two charged residues for the interaction of PAI-1 with LRP1 and three charged residues for the interaction of uPA:PAI-1 complexes with LRP1. An enhanced affinity resulting from the interaction of three regions of the uPA:PAI-1 complex with LDLa repeats on LRP1 provided an explanation for the increased affinity of uPA:PAI-1 complexes for LRP1. Mutational analysis revealed an overlap between LRP1 binding and binding of a small-molecule inhibitor of PAI-1, CDE-096, confirming an important role for Lys-207 in the interaction of PAI-1 with LRP1 and of the orientations of Lys-207, -88, and -80 for the interaction of uPA:PAI-1 complexes with LRP1.
-
high affinity binding of plasminogen activator inhibitor 1 complexes to ldl receptor related protein 1 requires lysines 80 88 and 207
Journal of Biological Chemistry, 2020Co-Authors: Mary Migliorini, Daniel A Lawrence, Anqi Zhou, Cory D Emal, Dudley K StricklandAbstract:It is well-established that complexes of plasminogen-activator inhibitor 1 (PAI-1) with its target enzymes bind tightly to low-density lipoprotein (LDL) receptor-related protein 1 (LRP1), but the molecular details of this interaction are not well-defined. Furthermore, considerable controversy exists in the literature regarding the nature of the interaction of free PAI-1 with LRP1. In this study, we examined the binding of free PAI-1 and complexes of PAI-1 with low-molecular-weight urokinase-type plasminogen activator to LRP1. Our results confirmed that uPA:PAI-1 complexes bind LRP1 with ∼100-fold increased affinity over PAI-1 alone. Chemical modification of PAI-1 confirmed an essential requirement of lysine residues in PAI-1 for the interactions of both PAI-1 and uPA:PAI-1 complexes with LRP1. Results of surface plasmon resonance measurements supported a bivalent binding model in which multiple sites on PAI-1 and uPA:PAI-1 complexes interact with complementary sites on LRP1. An ionic-strength dependence of binding suggested the critical involvement of two charged residues for the interaction of PAI-1 with LRP1 and three charged residues for the interaction of uPA:PAI-1 complexes with LRP1. An enhanced affinity resulting from the interaction of three regions of the uPA:PAI-1 complex with LDLa repeats on LRP1 provided an explanation for the increased affinity of uPA:PAI-1 complexes for LRP1. Mutational analysis revealed an overlap between LRP1 binding and binding of a small-molecule inhibitor of PAI-1, CDE-096, confirming an important role for Lys-207 in the interaction of PAI-1 with LRP1 and of the orientations of Lys-207, -88, and -80 for the interaction of uPA:PAI-1 complexes with LRP1.
-
LRP1 low density lipoprotein receptor related protein 1 regulates smooth muscle contractility by modulating ca 2 signaling and expression of cytoskeleton related proteins
Arteriosclerosis Thrombosis and Vascular Biology, 2018Co-Authors: Zhekang Ying, Mary Migliorini, Rebeca Galisteo, Debra L Rateri, Alan Daugherty, Erick O Hernandezochoa, William E Fondrie, Brian Hampton, Martin F Schneider, Dudley K StricklandAbstract:Objective- Mutations affecting contractile-related proteins in the ECM (extracellular matrix), microfibrils, or vascular smooth muscle cells can predispose the aorta to aneurysms. We reported previously that the LRP1 (low-density lipoprotein receptor-related protein 1) maintains vessel wall integrity, and smLRP1-/- mice exhibited aortic dilatation. The current study focused on defining the mechanisms by which LRP1 regulates vessel wall function and integrity. Approach and Results- Isometric contraction assays demonstrated that vasoreactivity of LRP1-deficient aortic rings was significantly attenuated when stimulated with vasoconstrictors, including phenylephrine, thromboxane receptor agonist U-46619, increased potassium, and L-type Ca2+ channel ligand FPL-64176. Quantitative proteomics revealed proteins involved in actin polymerization and contraction were significantly downregulated in aortas of smLRP1-/- mice. However, studies with calyculin A indicated that although aortic muscle from smLRP1-/- mice can contract in response to calyculin A, a role for LRP1 in regulating the contractile machinery is not revealed. Furthermore, intracellular calcium imaging experiments identified defects in calcium release in response to a RyR (ryanodine receptor) agonist in smLRP1-/- aortic rings and cultured vascular smooth muscle cells. Conclusions- These results identify a critical role for LRP1 in modulating vascular smooth muscle cell contraction by regulating calcium signaling events that potentially protect against aneurysm development.
Steven L. Gonias - One of the best experts on this subject based on the ideXlab platform.
-
LRP1 deficiency in microglia blocks neuro-inflammation in the spinal dorsal horn and neuropathic pain processing.
Glia, 2019Co-Authors: Coralie Brifault, Wendy M Campana, Hyojun Kwon, Steven L. GoniasAbstract:Following injury to the peripheral nervous system (PNS), microglia in the spinal dorsal horn (SDH) become activated and contribute to the development of local neuro-inflammation, which may regulate neuropathic pain processing. The molecular mechanisms that control microglial activation and its effects on neuropathic pain remain incompletely understood. We deleted the gene encoding the plasma membrane receptor, LDL Receptor-related Protein-1 (LRP1), conditionally in microglia using two distinct promoter-Cre recombinase systems in mice. LRP1 deletion in microglia blocked development of tactile allodynia, a neuropathic pain-related behavior, after partial sciatic nerve ligation (PNL). LRP1 deletion also substantially attenuated microglial activation and pro-inflammatory cytokine expression in the SDH following PNL. Because LRP1 shedding from microglial plasma membranes generates a highly pro-inflammatory soluble product, we demonstrated that factors which activate spinal cord microglia, including lipopolysaccharide (LPS) and colony-stimulating factor-1, promote LRP1 shedding. Proteinases known to mediate LRP1 shedding, including ADAM10 and ADAM17, were expressed at increased levels in the SDH after PNL. Furthermore, LRP1-deficient microglia in cell culture expressed significantly decreased levels of interleukin-1β and interleukin-6 when treated with LPS. We conclude that in the SDH, microglial LRP1 plays an important role in establishing and/or amplifying local neuro-inflammation and neuropathic pain following PNS injury. The responsible mechanism most likely involves proteolytic release of LRP1 from the plasma membrane to generate a soluble product that functions similarly to pro-inflammatory cytokines in mediating crosstalk between cells in the SDH and in regulating neuropathic pain.
-
shedding of membrane associated ldl receptor related protein 1 from microglia amplifies and sustains neuroinflammation
Journal of Biological Chemistry, 2017Co-Authors: Coralie Brifault, Andrew S Gilder, Emilia Laudati, Michael A Banki, Steven L. GoniasAbstract:In the CNS, microglia are activated in response to injury or infection and in neurodegenerative diseases. The endocytic and cell signaling receptor, LDL receptor-related protein-1 (LRP1), is reported to suppress innate immunity in macrophages and oppose microglial activation. The goal of this study was to identify novel mechanisms by which LRP1 may regulate microglial activation. Using primary cultures of microglia isolated from mouse brains, we demonstrated that LRP1 gene silencing increases expression of proinflammatory mediators; however, the observed response was modest. By contrast, the LRP1 ligand, receptor-associated protein (RAP), robustly activated microglia, and its activity was attenuated in LRP1-deficient cells. An important element of the mechanism by which RAP activated microglia was its ability to cause LRP1 shedding from the plasma membrane. This process eliminated cellular LRP1, which is anti-inflammatory, and generated a soluble product, shed LRP1 (sLRP1), which is potently proinflammatory. Purified sLRP1 induced expression of multiple proinflammatory cytokines and the mRNA encoding inducible nitric-oxide synthase in both LRP1-expressing and -deficient microglia. LPS also stimulated LRP1 shedding, as did the heat-shock protein and LRP1 ligand, calreticulin. Other LRP1 ligands, including α2-macroglobulin and tissue-type plasminogen activator, failed to cause LRP1 shedding. Treatment of microglia with a metalloproteinase inhibitor inhibited LRP1 shedding and significantly attenuated RAP-induced cytokine expression. RAP and sLRP1 both caused neuroinflammation in vivo when administered by stereotaxic injection into mouse spinal cords. Collectively, these results suggest that LRP1 shedding from microglia may amplify and sustain neuroinflammation in response to proinflammatory stimuli.
-
ldl receptor related protein 1 regulates nfκb and microrna 155 in macrophages to control the inflammatory response
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Elisabetta Mantuano, Coralie Brifault, Michael S Lam, Pardis Azmoon, Andrew S Gilder, Steven L. GoniasAbstract:LDL receptor-related protein-1 (LRP1) is an endocytic and cell-signaling receptor. In mice in which LRP1 is deleted in myeloid cells, the response to lipopolysaccharide (LPS) was greatly exacerbated. LRP1 deletion in macrophages in vitro, under the control of tamoxifen-activated Cre-ER(T) fusion protein, robustly increased expression of proinflammatory cytokines and chemokines. In LRP1-expressing macrophages, proinflammatory mediator expression was regulated by LRP1 ligands in a ligand-specific manner. The LRP1 agonists, α2-macroglobulin and tissue-type plasminogen activator, attenuated expression of inflammatory mediators, even in the presence of LPS. The antagonists, receptor-associated protein (RAP) and lactoferrin (LF), and LRP1-specific antibody had the entirely opposite effect, promoting inflammatory mediator expression and mimicking LRP1 deletion. NFκB was rapidly activated in response to RAP and LF and responsible for the initial increase in expression of proinflammatory mediators. RAP and LF also significantly increased expression of microRNA-155 (miR-155) after a lag phase of about 4 h. miR-155 expression reflected, at least in part, activation of secondary cell-signaling pathways downstream of TNFα. Although miR-155 was not involved in the initial induction of cytokine expression in response to LRP1 antagonists, miR-155 was essential for sustaining the proinflammatory response. We conclude that LRP1, NFκB, and miR-155 function as members of a previously unidentified system that has the potential to inhibit or sustain inflammation, depending on the continuum of LRP1 ligands present in the macrophage microenvironment.
-
ldl receptor related protein 1 a regulator of inflammation in atherosclerosis cancer and injury to the nervous system
American Journal of Pathology, 2014Co-Authors: Steven L. Gonias, Marie W CampanaAbstract:Low-density lipoprotein receptor–related protein-1 (LRP1) is an endocytic receptor for numerous proteins that are both structurally and functionally diverse. In some cell types, LRP1-mediated endocytosis is coupled to activation of cell signaling. LRP1 also regulates the composition of the plasma membrane and may, thereby, indirectly regulate the activity of other cell-signaling receptors. Given the scope of LRP1 ligands and its multifunctional nature, it is not surprising that numerous biological activities have been attributed to this receptor. LRP1 gene deletion is embryonic-lethal in mice. However, elegant studies using Cre-LoxP recombination have helped elucidate the function of LRP1 in mature normal and pathological tissues. One major theme that has emerged is the role of LRP1 as a regulator of inflammation. In this review, we will describe evidence for LRP1 as a regulator of inflammation in atherosclerosis, cancer, and injury to the nervous system.
-
LRP1 assembles unique co receptor systems to initiate cell signaling in response to tissue type plasminogen activator and myelin associated glycoprotein
Journal of Biological Chemistry, 2013Co-Authors: Elisabetta Mantuano, Steven L. GoniasAbstract:In addition to functioning as an activator of fibrinolysis, tissue-type plasminogen activator (tPA) interacts with neurons and regulates multiple aspects of neuronal cell physiology. In this study, we examined the mechanism by which tPA initiates cell signaling in PC12 and N2a neuron-like cells. We demonstrate that enzymatically active and inactive tPA (EI-tPA) activate ERK1/2 in a biphasic manner. Rapid ERK1/2 activation is dependent on LDL receptor-related protein-1 (LRP1). In the second phase, ERK1/2 is activated by tPA independently of LRP1. The length of the LRP1-dependent phase varied inversely with the tPA concentration. Rapid ERK1/2 activation in response to EI-tPA and activated α2-macroglobulin (α2M*) required the NMDA receptor and Trk receptors, which assemble with LRP1 into a single pathway. Assembly of this signaling system may have been facilitated by the bifunctional adapter protein, PSD-95, which associated with LRP1 selectively in cells treated with EI-tPA or α2M*. Myelin-associated glycoprotein binds to LRP1 with high affinity but failed to induce phosphorylation of TrkA or ERK1/2. Instead, myelin-associated glycoprotein recruited p75 neurotrophin receptor (p75NTR) into a complex with LRP1 and activated RhoA. p75NTR was not recruited by other LRP1 ligands, including EI-tPA and α2M*. Lactoferrin functioned as an LRP1 signaling antagonist, inhibiting Trk receptor phosphorylation and ERK1/2 activation in response to EI-tPA. These results demonstrate that LRP1-initiated cell signaling is ligand-dependent. Proteins that activate cell signaling by binding to LRP1 assemble different co-receptor systems. Ligand-specific co-receptor recruitment provides a mechanism by which one receptor, LRP1, may trigger different signaling responses.
Mary Migliorini - One of the best experts on this subject based on the ideXlab platform.
-
high affinity binding of ldl receptor related protein 1 to matrix metalloprotease 1 requires protease inhibitor complex formation
Biochemistry, 2020Co-Authors: Allison L Arai, Mary Migliorini, Elizabeth Hahndantona, David Peeney, William G Stetlerstevenson, Selen Muratoglu, Dudley K StricklandAbstract:Matrix metalloprotease (MMP) activation contributes to the degradation of the extracellular matrix (ECM), resulting in a multitude of pathologies. Low-density lipoprotein receptor-related protein 1 (LRP1) is a multifaceted endocytic and signaling receptor that is responsible for internalization and lysosomal degradation of diverse proteases, protease inhibitors, and lipoproteins along with numerous other proteins. In this study, we identified MMP-1 as a novel LRP1 ligand. Binding studies employing surface plasmon resonance revealed that both proMMP-1 and active MMP-1 bind to purified LRP1 with equilibrium dissociation constants (KD) of 19 and 25 nM, respectively. We observed that human aortic smooth muscle cells readily internalize and degrade 125I-labeled proMMP-1 in an LRP1-mediated process. Our binding data also revealed that all tissue inhibitors of metalloproteases (TIMPs) bind to LRP1 with KD values ranging from 23 to 33 nM. Interestingly, the MMP-1/TIMP-1 complex bound to LRP1 with an affinity (KD = 0.6 nM) that was 30-fold higher than that of either component alone, revealing that LRP1 prefers the protease:inhibitor complex as a ligand. Of note, modification of lysine residues on either proMMP-1 or TIMP-1 ablated the ability of the MMP-1/TIMP-1 complex to bind to LRP1. LRP1's preferential binding to enzyme:inhibitor complexes was further supported by the higher binding affinity for proMMP-9/TIMP-1 complexes than for either of these two components alone. LRP1 has four clusters of ligand-binding repeats, and MMP-1, TIMP-1, and MMP-1/TIMP-1 complexes bound to cluster III most avidly. Our results reveal an important role for LRP1 in controlling ECM homeostasis by regulating MMP-1 and MMP-9 levels.
-
high affinity binding of plasminogen activator inhibitor 1 complexes to ldl receptor related protein 1 requires lysines 80 88 and 207
Journal of Biological Chemistry, 2020Co-Authors: Mary Migliorini, Daniel A Lawrence, Anqi Zhou, Cory D Emal, Dudley K StricklandAbstract:It is well-established that complexes of plasminogen-activator inhibitor 1 (PAI-1) with its target enzymes bind tightly to low-density lipoprotein (LDL) receptor-related protein 1 (LRP1), but the molecular details of this interaction are not well-defined. Furthermore, considerable controversy exists in the literature regarding the nature of the interaction of free PAI-1 with LRP1. In this study, we examined the binding of free PAI-1 and complexes of PAI-1 with low-molecular-weight urokinase-type plasminogen activator to LRP1. Our results confirmed that uPA:PAI-1 complexes bind LRP1 with ∼100-fold increased affinity over PAI-1 alone. Chemical modification of PAI-1 confirmed an essential requirement of lysine residues in PAI-1 for the interactions of both PAI-1 and uPA:PAI-1 complexes with LRP1. Results of surface plasmon resonance measurements supported a bivalent binding model in which multiple sites on PAI-1 and uPA:PAI-1 complexes interact with complementary sites on LRP1. An ionic-strength dependence of binding suggested the critical involvement of two charged residues for the interaction of PAI-1 with LRP1 and three charged residues for the interaction of uPA:PAI-1 complexes with LRP1. An enhanced affinity resulting from the interaction of three regions of the uPA:PAI-1 complex with LDLa repeats on LRP1 provided an explanation for the increased affinity of uPA:PAI-1 complexes for LRP1. Mutational analysis revealed an overlap between LRP1 binding and binding of a small-molecule inhibitor of PAI-1, CDE-096, confirming an important role for Lys-207 in the interaction of PAI-1 with LRP1 and of the orientations of Lys-207, -88, and -80 for the interaction of uPA:PAI-1 complexes with LRP1.
-
high affinity binding of plasminogen activator inhibitor 1 complexes to ldl receptor related protein 1 requires lysines 80 88 and 207
Journal of Biological Chemistry, 2020Co-Authors: Mary Migliorini, Daniel A Lawrence, Shihhon Li, Anqi Zhou, Cory D Emal, Dudley K StricklandAbstract:: It is well established that complexes of plasminogen-activator inhibitor 1 (PAI-1) with its target enzymes bind tightly to LDL receptor-related protein 1 (LRP1), but the molecular details of this interaction are not well defined. Further, considerable controversy exists in the literature regarding the nature of the interaction of free PAI-1 with LRP1. In this study, we examined the binding of free PAI-1 and complexes of PAI-1 with low-molecular-weight urokinase-type plasminogen activator (LMWuPA) to LRP1. Our results confirmed that uPA:PAI-1 complexes bind LRP1 with ~100-fold increased affinity over PAI-1 alone. Chemical modification of PAI-1 confirmed an essential requirement of lysine residues in PAI-1 for the interactions of both PAI-1 and uPA:PAI-1 complexes with LRP1. Results of surface plasmon resonance measurements supported a bivalent binding model in which multiple sites on PAI-1 and uPA:PAI-1 complexes interact with complementary sites on LRP1. An ionic-strength dependence of binding suggested the critical involvement of two charged residues for the interaction of PAI-1 with LRP1 and three charged residues for the interaction of uPA:PAI-1 complexes with LRP1. An enhanced affinity resulting from the interaction of three regions of the uPA:PAI-1 complex with LDLa repeats on LRP1 provided an explanation for the increased affinity of uPA:PAI-1 complexes for LRP1. Mutational analysis revealed an overlap between LRP1 binding and binding of a small-molecule inhibitor of PAI-1, CDE-096, confirming an important role for Lys-207 in the interaction of PAI-1 with LRP1 and of the orientations of Lys-207, -88, and -80 for the interaction of uPA:PAI-1 complexes with LRP1.
-
LRP1 low density lipoprotein receptor related protein 1 regulates smooth muscle contractility by modulating ca 2 signaling and expression of cytoskeleton related proteins
Arteriosclerosis Thrombosis and Vascular Biology, 2018Co-Authors: Zhekang Ying, Mary Migliorini, Rebeca Galisteo, Debra L Rateri, Alan Daugherty, Erick O Hernandezochoa, William E Fondrie, Brian Hampton, Martin F Schneider, Dudley K StricklandAbstract:Objective- Mutations affecting contractile-related proteins in the ECM (extracellular matrix), microfibrils, or vascular smooth muscle cells can predispose the aorta to aneurysms. We reported previously that the LRP1 (low-density lipoprotein receptor-related protein 1) maintains vessel wall integrity, and smLRP1-/- mice exhibited aortic dilatation. The current study focused on defining the mechanisms by which LRP1 regulates vessel wall function and integrity. Approach and Results- Isometric contraction assays demonstrated that vasoreactivity of LRP1-deficient aortic rings was significantly attenuated when stimulated with vasoconstrictors, including phenylephrine, thromboxane receptor agonist U-46619, increased potassium, and L-type Ca2+ channel ligand FPL-64176. Quantitative proteomics revealed proteins involved in actin polymerization and contraction were significantly downregulated in aortas of smLRP1-/- mice. However, studies with calyculin A indicated that although aortic muscle from smLRP1-/- mice can contract in response to calyculin A, a role for LRP1 in regulating the contractile machinery is not revealed. Furthermore, intracellular calcium imaging experiments identified defects in calcium release in response to a RyR (ryanodine receptor) agonist in smLRP1-/- aortic rings and cultured vascular smooth muscle cells. Conclusions- These results identify a critical role for LRP1 in modulating vascular smooth muscle cell contraction by regulating calcium signaling events that potentially protect against aneurysm development.
-
generation of a potent low density lipoprotein receptor related protein 1 LRP1 antagonist by engineering a stable form of the receptor associated protein rap d3 domain
Journal of Biological Chemistry, 2015Co-Authors: Joni M Prasad, Mary Migliorini, Rebeca Galisteo, Dudley K StricklandAbstract:Abstract The low density lipoprotein receptor-related protein 1 (LRP1) is a member of the low density lipoprotein receptor family and plays important roles in a number of physiological and pathological processes. Expression of LRP1 requires the receptor-associated protein (RAP), a molecular chaperone that binds LRP1 and other low density lipoprotein receptor family members in the endoplasmic reticulum and traffics with them to the Golgi where the acidic environment causes its dissociation. Exogenously added RAP is a potent LRP1 antagonist and binds to LRP1 on the cell surface, preventing ligands from binding. Following endocytosis, RAP dissociates in the acidic endosome, allowing LRP1 to recycle back to the cell surface. The acid-induced dissociation of RAP is mediated by its D3 domain, a relatively unstable three-helical bundle that denatures at pH <6.2 due to protonation of key histidine residues on helices 2 and 3. To develop an LRP1 inhibitor that does not dissociate at low pH, we introduced a disulfide bond between the second and third helices in the RAP D3 domain. By combining this disulfide bond with elimination of key histidine residues, we generated a stable RAP molecule that is resistant to both pH- and heat-induced denaturation. This molecule bound to LRP1 with high affinity at both neutral and acidic pH and proved to be a potent inhibitor of LRP1 function both in vitro and in vivo, suggesting that our stable RAP molecule may be useful in multiple pathological settings where LRP1 blockade has been shown to be effective.
Elisabetta Mantuano - One of the best experts on this subject based on the ideXlab platform.
-
ldl receptor related protein 1 regulates nfκb and microrna 155 in macrophages to control the inflammatory response
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Elisabetta Mantuano, Coralie Brifault, Michael S Lam, Pardis Azmoon, Andrew S Gilder, Steven L. GoniasAbstract:LDL receptor-related protein-1 (LRP1) is an endocytic and cell-signaling receptor. In mice in which LRP1 is deleted in myeloid cells, the response to lipopolysaccharide (LPS) was greatly exacerbated. LRP1 deletion in macrophages in vitro, under the control of tamoxifen-activated Cre-ER(T) fusion protein, robustly increased expression of proinflammatory cytokines and chemokines. In LRP1-expressing macrophages, proinflammatory mediator expression was regulated by LRP1 ligands in a ligand-specific manner. The LRP1 agonists, α2-macroglobulin and tissue-type plasminogen activator, attenuated expression of inflammatory mediators, even in the presence of LPS. The antagonists, receptor-associated protein (RAP) and lactoferrin (LF), and LRP1-specific antibody had the entirely opposite effect, promoting inflammatory mediator expression and mimicking LRP1 deletion. NFκB was rapidly activated in response to RAP and LF and responsible for the initial increase in expression of proinflammatory mediators. RAP and LF also significantly increased expression of microRNA-155 (miR-155) after a lag phase of about 4 h. miR-155 expression reflected, at least in part, activation of secondary cell-signaling pathways downstream of TNFα. Although miR-155 was not involved in the initial induction of cytokine expression in response to LRP1 antagonists, miR-155 was essential for sustaining the proinflammatory response. We conclude that LRP1, NFκB, and miR-155 function as members of a previously unidentified system that has the potential to inhibit or sustain inflammation, depending on the continuum of LRP1 ligands present in the macrophage microenvironment.
-
LRP1 assembles unique co receptor systems to initiate cell signaling in response to tissue type plasminogen activator and myelin associated glycoprotein
Journal of Biological Chemistry, 2013Co-Authors: Elisabetta Mantuano, Steven L. GoniasAbstract:In addition to functioning as an activator of fibrinolysis, tissue-type plasminogen activator (tPA) interacts with neurons and regulates multiple aspects of neuronal cell physiology. In this study, we examined the mechanism by which tPA initiates cell signaling in PC12 and N2a neuron-like cells. We demonstrate that enzymatically active and inactive tPA (EI-tPA) activate ERK1/2 in a biphasic manner. Rapid ERK1/2 activation is dependent on LDL receptor-related protein-1 (LRP1). In the second phase, ERK1/2 is activated by tPA independently of LRP1. The length of the LRP1-dependent phase varied inversely with the tPA concentration. Rapid ERK1/2 activation in response to EI-tPA and activated α2-macroglobulin (α2M*) required the NMDA receptor and Trk receptors, which assemble with LRP1 into a single pathway. Assembly of this signaling system may have been facilitated by the bifunctional adapter protein, PSD-95, which associated with LRP1 selectively in cells treated with EI-tPA or α2M*. Myelin-associated glycoprotein binds to LRP1 with high affinity but failed to induce phosphorylation of TrkA or ERK1/2. Instead, myelin-associated glycoprotein recruited p75 neurotrophin receptor (p75NTR) into a complex with LRP1 and activated RhoA. p75NTR was not recruited by other LRP1 ligands, including EI-tPA and α2M*. Lactoferrin functioned as an LRP1 signaling antagonist, inhibiting Trk receptor phosphorylation and ERK1/2 activation in response to EI-tPA. These results demonstrate that LRP1-initiated cell signaling is ligand-dependent. Proteins that activate cell signaling by binding to LRP1 assemble different co-receptor systems. Ligand-specific co-receptor recruitment provides a mechanism by which one receptor, LRP1, may trigger different signaling responses.
-
low density lipoprotein receptor related protein 1 LRP1 dependent cell signaling promotes neurotrophic activity in embryonic sensory neurons
PLOS ONE, 2013Co-Authors: Kazuyo Yamauchi, Tomonori Yamauchi, Elisabetta Mantuano, Kenichi Murakami, Kenneth Henry, Kazuhisa Takahashi, Wendy M CampanaAbstract:Developing sensory neurons require neurotrophic support for survival, neurite outgrowth and myelination. The low-density lipoprotein receptor-related protein-1 (LRP1) transactivates Trk receptors and thereby functions as a putative neurotrophin. Herein, we show that LRP1 is abundantly expressed in developing dorsal root ganglia (DRG) and that LRP1-dependent cell signaling supports survival, neurite extension and receptivity to Schwann cells even in the absence of neurotrophins. Cultured embryonic DRG neurons (E15) were treated with previously characterized LRP1 ligands, LRP1-receptor binding domain of α2-macroglobulin (RBD), hemopexin domain of MMP-9 (PEX) or controls (GST) for two weeks. These structurally diverse LRP1 ligands significantly activated and sustained extracellular signal-regulated kinases (ERK1/2) 5-fold (p 2 weeks in vitro, to an extent equaling NGF, a finding associated with canonical signaling mechanisms and blockade of caspase-3 cleavage. LRP1 ligand-induced survival and sprouting were blocked by co-incubation with the LRP1 antagonist, receptor associated protein (RAP), whereas RAP had no effect on NGF-induced activity. Site directed mutagenesis of the LRP1 ligand, RBD, in which Lys1370 and Lys1374 are converted to alanine to preclude LRP1 binding, were ineffective in promoting cell signaling, survival or inducing neurite extension in primary sensory neurons, confirming LRP1 specificity. Furthermore, LRP1-induced neurite sprouting was mediated by Src-family kinase (SFK) activation, suggesting transactivation of Trk receptors. Co-cultures of primary embryonic neurons and Schwann cells showed that LRP1 agonists promoted axonal receptivity to myelination to Schwann cells. Collectively, these findings identify LRP1 as a novel and perhaps essential trophic molecule for sensory neuronal survival and development.
-
ldl receptor related protein 1 is a sialic acid independent receptor for myelin associated glycoprotein that functions in neurite outgrowth inhibition by mag and cns myelin
Journal of Cell Science, 2013Co-Authors: Travis L Stiles, Elisabetta Mantuano, Travis L Dickendesher, Alban Gaultier, Anthony Fernandezcastaneda, Roman J Giger, Steven L. GoniasAbstract:In the injured adult mammalian central nervous system (CNS), products are generated that inhibit neuronal sprouting and regeneration. In recent years, most attention has focused on the myelin-associated inhibitory proteins (MAIs) Nogo-A, OMgp, and myelin-associated glycoprotein (MAG). Binding of MAIs to neuronal cell-surface receptors leads to activation of RhoA, growth cone collapse, and neurite outgrowth inhibition. In the present study, we identify low-density lipoprotein (LDL) receptor-related protein-1 (LRP1) as a high-affinity, endocytic receptor for MAG. In contrast with previously identified MAG receptors, binding of MAG to LRP1 occurs independently of terminal sialic acids. In primary neurons, functional inactivation of LRP1 with receptor-associated protein, depletion by RNA interference (RNAi) knock-down, or LRP1 gene deletion is sufficient to significantly reverse MAG and myelin-mediated inhibition of neurite outgrowth. Similar results are observed when LRP1 is antagonized in PC12 and N2a cells. By contrast, inhibiting LRP1 does not attenuate inhibition of neurite outgrowth caused by chondroitin sulfate proteoglycans. Mechanistic studies in N2a cells showed that LRP1 and p75NTR associate in a MAG-dependent manner and that MAG-mediated activation of RhoA may involve both LRP1 and p75NTR. LRP1 derivatives that include the complement-like repeat clusters CII and CIV bind MAG and other MAIs. When CII and CIV were expressed as Fc-fusion proteins, these proteins, purified full-length LRP1 and shed LRP1 all attenuated the inhibition of neurite outgrowth caused by MAG and CNS myelin in primary neurons. Collectively, our studies identify LRP1 as a novel MAG receptor that functions in neurite outgrowth inhibition.
-
low density lipoprotein receptor related protein LRP1 regulates rac1 and rhoa reciprocally to control schwann cell adhesion and migration
Journal of Biological Chemistry, 2010Co-Authors: Elisabetta Mantuano, Steven L. Gonias, Marie W CampanaAbstract:LDL receptor-related protein (LRP1) is expressed by Schwann cells in vivo mainly after injury to the peripheral nervous system (PNS). Schwann cells in primary culture, which provide a model of Schwann cells in the injured PNS, also express abundant LRP1. Herein, we show that LRP1 gene-silencing or treatment with receptor-associated protein (RAP) promotes Schwann cell adhesion and inhibits cell migration on fibronectin. LRP1 gene-silencing also resulted in the formation of prominent focal adhesions and actin stress fibers. These changes, which were induced by loss of LRP1 expression or activity, were explained mechanistically by an increase in activated RhoA, coupled with a decrease in activated Rac1. Known LRP1 ligands, including matrix metalloprotease-9, tissue-type plasminogen activator, and α2-macroglobulin activated Rac1 in LRP1-expressing Schwann cells. An inhibitor of Rac1 activation promoted Schwann cell adhesion. Conversely, in cells in which LRP1 was silenced, a Rho kinase inhibitor promoted migration and inhibited adhesion. These results demonstrate that direct binding of ligands to LRP1 controls activation of small Rho family GTPases. The effects of LRP1 gene-silencing and RAP implicate autocrine pathways involving endogenously produced LRP1 ligands. Regulation of Schwann cell migration by LRP1 may be important in PNS injury.
Joerg Heeren - One of the best experts on this subject based on the ideXlab platform.
-
naturally occurring variants in LRP1 low density lipoprotein receptor related protein 1 affect hdl high density lipoprotein metabolism through abca1 atp binding cassette a1 and sr b1 scavenger receptor class b type 1 in humans
Arteriosclerosis Thrombosis and Vascular Biology, 2018Co-Authors: Federico Oldoni, Julian C Van Capelleveen, N Dalila, Justina C Wolters, Joerg Heeren, Richard J Sinke, David Y Hui, Geesje M Dallingathie, Ruth Frikkeschmidt, Kees HovinghAbstract:Objective— Studies into the role of LRP1 (low-density lipoprotein receptor–related protein 1) in human lipid metabolism are scarce. Although it is known that a common variant in LRP1 (rs116133520) ...
-
The adaptor protein PID1 regulates receptor-dependent endocytosis of postprandial triglyceride-rich lipoproteins
'Elsevier BV', 2018Co-Authors: Alexander W. Fischer, Markus Heine, Philip L.s.m. Gordts, Kirstin Albers, Lucia M. Krott, Britta Hoffzimmer, Hartwig Schmale, Ludger Scheja, Joerg HeerenAbstract:Objective: Insulin resistance is associated with impaired receptor dependent hepatic uptake of triglyceride-rich lipoproteins (TRL), promoting hypertriglyceridemia and atherosclerosis. Next to low-density lipoprotein (LDL) receptor (LDLR) and syndecan-1, the LDLR-related protein 1 (LRP1) stimulated by insulin action contributes to the rapid clearance of TRL in the postprandial state. Here, we investigated the hypothesis that the adaptor protein phosphotyrosine interacting domain-containing protein 1 (PID1) regulates LRP1 function, thereby controlling hepatic endocytosis of postprandial lipoproteins. Methods: Localization and interaction of PID1 and LRP1 in cultured hepatocytes was studied by confocal microscopy of fluorescent tagged proteins, by indirect immunohistochemistry of endogenous proteins, by GST-based pull down and by immunoprecipitation experiments. The in vivo relevance of PID1 was assessed using whole body as well as liver-specific Pid1-deficient mice on a wild type or Ldlr-deficient (Ldlr−/−) background. Intravital microscopy was used to study LRP1 translocation in the liver. Lipoprotein metabolism was investigated by lipoprotein profiling, gene and protein expression as well as organ-specific uptake of radiolabelled TRL. Results: PID1 co-localized in perinuclear endosomes and was found associated with LRP1 under fasting conditions. We identified the distal NPxY motif of the intracellular C-terminal domain (ICD) of LRP1 as the site critical for the interaction with PID1. Insulin-mediated NPxY-phosphorylation caused the dissociation of PID1 from the ICD, causing LRP1 translocation to the plasma membrane. PID1 deletion resulted in higher LRP1 abundance at the cell surface, higher LDLR protein levels and, paradoxically, reduced total LRP1. The latter can be explained by higher receptor shedding, which we observed in cultured Pid1-deficient hepatocytes. Consistently, PID1 deficiency alone led to increased LDLR-dependent endocytosis of postprandial lipoproteins and lower plasma triglycerides. In contrast, hepatic PID1 deletion on an Ldlr−/− background reduced lipoprotein uptake into liver and caused plasma TRL accumulation. Conclusions: By acting as an insulin-dependent retention adaptor, PID1 serves as a regulator of LRP1 function controlling the disposal of postprandial lipoproteins. PID1 inhibition provides a novel approach to lower plasma levels of pro-atherogenic TRL remnants by stimulating endocytic function of both LRP1 and LDLR in the liver. Keywords: Lipid metabolism, Insulin, Adaptor proteins, Lipoprotein receptors, Endocytosis, Atherosclerosi
-
insulin stimulates hepatic low density lipoprotein receptor related protein 1 LRP1 to increase postprandial lipoprotein clearance
Atherosclerosis, 2009Co-Authors: Alexander Laatsch, Martin Merkel, Philippa J Talmud, Thomas Grewal, Ulrike Beisiegel, Joerg HeerenAbstract:Abstract Background While the role of insulin in glucose uptake and its aberration in diabetes are well established, the effect of insulin on lipoprotein clearance in the postprandial phase is not yet fully understood. The dietary lipids are carried in chylomicron remnants (CR) which are taken up into the liver mainly via LDLR-related protein 1 (LRP1). In this study, the effect of insulin on LRP1-mediated hepatic CR uptake was investigated. Methods The study was based on determining the subcellular localisation of LRP1 by subcellular fractionation and immunofluorescence microscopy and correlating those findings with the hepatic uptake of fluorescently or radioactively labelled LRP1-specific ligands and CR in hepatoma cells, primary hepatocytes and mouse models. Results and conclusion In vitro and in vivo , insulin stimulated the translocation of hepatic LRP1 from intracellular vesicles to the plasma membrane, which correlates with an increased uptake of LRP1-specific ligands. In wild-type mice, a glucose-induced insulin response increased the hepatic uptake of LRP1 ligands while in leptin-deficient obese mice ( ob / ob ), which are characterised by hepatic insulin resistance, insulin-inducible LRP1 ligand uptake was abolished. Finally, upon hepatic LRP1 knockdown, insulin no longer significantly enhanced CR uptake into the liver. The insulin-induced LRP1-mediated CR uptake, as demonstrated here, suggests that impaired hepatic LRP1 translocation can contribute to the postprandial lipaemia in insulin resistance.
