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Wu C, Chen J, Zhang J, Hong H, Jiang J, Ji C, Li C, Xia M, Xu G, Cui Z. Extracellular vesicles loaded with ApoB-100 protein affect the occurrence of coronary heart disease in patients after injury of spinal cord. Int J Biol Macromol 2024; 277:134330. [PMID: 39089550 DOI: 10.1016/j.ijbiomac.2024.134330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 07/24/2024] [Accepted: 07/29/2024] [Indexed: 08/04/2024]
Abstract
Spinal cord injury (SCI) patients have an increased susceptibility to coronary heart disease (CHD) due to dysregulated lipid deposition. We conducted a comprehensive investigation to gain insights into the specific roles of Apolipoprotein B-100 (APOB-100) in the development of CHD in patients suffering from SCI. First, we established an SCI rat model through semitransection. APOB-100 expression in plasma exosomes obtained from patients were determined. Subsequently, we found APOB-100 affected macrophage polarization when treating co-cultured neurons/macrophages lacking Sortilin with extracellular vesicles derived from SCI rats, where APOB-100 co-immunoprecipitated with Sortilin. Moreover, APOB-100 upregulation reduced neuronal cell viability and triggered apoptosis by upregulating Sortilin, leading to a decline in the Basso, Beattie, and Bresnahan (BBB) scale, exacerbation of neuron injury, increased macrophage infiltration, and elevated blood lipid-related indicators in SCI rats, which could be reversed by silencing Sortilin. In conclusion, APOB-100 from post-SCI patients' extracellular vesicles upregulates Sortilin, thereby endangering those patients to CHD.
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Affiliation(s)
- Chunshuai Wu
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China; Key Laboratory for Restoration Mechanism and Clinical Translation of Spinal Cord Injury, Nantong 226000, China; Research institute for Spine and spinal cord disease of Nantong University, Nantong 226000, China
| | - Jiajia Chen
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China
| | - Jinlong Zhang
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China
| | - Hongxiang Hong
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China
| | - Jiawei Jiang
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China
| | - Chunyan Ji
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China; Key Laboratory for Restoration Mechanism and Clinical Translation of Spinal Cord Injury, Nantong 226000, China; Research institute for Spine and spinal cord disease of Nantong University, Nantong 226000, China
| | - Chaochen Li
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China; Key Laboratory for Restoration Mechanism and Clinical Translation of Spinal Cord Injury, Nantong 226000, China; Research institute for Spine and spinal cord disease of Nantong University, Nantong 226000, China
| | - Mingjie Xia
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China
| | - Guanhua Xu
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China; Key Laboratory for Restoration Mechanism and Clinical Translation of Spinal Cord Injury, Nantong 226000, China; Research institute for Spine and spinal cord disease of Nantong University, Nantong 226000, China.
| | - Zhiming Cui
- Department of Spine surgery, The Second Affiliated Hospital of Nantong University, Nantong First People's Hospital, Nantong 226000, China; Key Laboratory for Restoration Mechanism and Clinical Translation of Spinal Cord Injury, Nantong 226000, China; Research institute for Spine and spinal cord disease of Nantong University, Nantong 226000, China.
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Yigit E, Deger O, Korkmaz K, Huner Yigit M, Uydu HA, Mercantepe T, Demir S. Propolis Reduces Inflammation and Dyslipidemia Caused by High-Cholesterol Diet in Mice by Lowering ADAM10/17 Activities. Nutrients 2024; 16:1861. [PMID: 38931216 PMCID: PMC11206409 DOI: 10.3390/nu16121861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/04/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
Atherosclerosis is one of the most important causes of cardiovascular diseases. A disintegrin and metalloprotease (ADAM)10 and ADAM17 have been identified as important regulators of inflammation in recent years. Our study investigated the effect of inhibiting these enzymes with selective inhibitor and propolis on atherosclerosis. In our study, C57BL/6J mice (n = 16) were used in the control and sham groups. In contrast, ApoE-/- mice (n = 48) were used in the case, water extract of propolis (WEP), ethanolic extract of propolis (EEP), GW280264X (GW-synthetic inhibitor), and solvent (DMSO and ethanol) groups. The control group was fed a control diet, and all other groups were fed a high-cholesterol diet for 16 weeks. WEP (400 mg/kg/day), EEP (200 mg/kg/day), and GW (100 µg/kg/day) were administered intraperitoneally for the last four weeks. Animals were sacrificed, and blood, liver, aortic arch, and aortic root tissues were collected. In serum, total cholesterol (TC), triglycerides (TGs), and glucose (Glu) were measured by enzymatic colorimetric method, while interleukin-1β (IL-1β), paraoxonase-1 (PON-1), and lipoprotein-associated phospholipase-A2 (Lp-PLA2) were measured by ELISA. Tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), myeloperoxidase (MPO), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-12 (IL-12) levels were measured in aortic arch by ELISA and ADAM10/17 activities were measured fluorometrically. In addition, aortic root and liver tissues were examined histopathologically and immunohistochemically (ADAM10 and sortilin primary antibody). In the WEP, EEP, and GW groups compared to the case group, TC, TG, TNF-α, IL-1β, IL-6, IL-12, PLA2, MPO, ADAM10/17 activities, plaque burden, lipid accumulation, ADAM10, and sortilin levels decreased, while IL-10 and PON-1 levels increased (p < 0.003). Our study results show that propolis can effectively reduce atherosclerosis-related inflammation and dyslipidemia through ADAM10/17 inhibition.
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Affiliation(s)
- Ertugrul Yigit
- Department of Medical Biochemistry, Faculty of Medicine, Karadeniz Technical University, 61080 Trabzon, Turkey;
| | - Orhan Deger
- Department of Medical Biochemistry, Faculty of Medicine, Karadeniz Technical University, 61080 Trabzon, Turkey;
| | - Katip Korkmaz
- Department of Nutrition and Dietetics, Faculty of Health Science, Karadeniz Technical University, 61080 Trabzon, Turkey; (K.K.); (S.D.)
| | - Merve Huner Yigit
- Department of Medical Biochemistry, Faculty of Medicine, Recep Tayyip Erdogan University, 53000 Rize, Turkey;
| | - Huseyin Avni Uydu
- Department of Medical Biochemistry, Faculty of Medicine, Samsun University, 55080 Samsun, Turkey;
| | - Tolga Mercantepe
- Department of Histology and Embryology, Faculty of Medicine, Recep Tayyip Erdogan University, 53000 Rize, Turkey;
| | - Selim Demir
- Department of Nutrition and Dietetics, Faculty of Health Science, Karadeniz Technical University, 61080 Trabzon, Turkey; (K.K.); (S.D.)
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Li C, Jiang N, Liu Y, Zhang Y, Chen R, Feng Y, Sang X, Chen Q. Toxoplasma sortilin interacts with secretory proteins and it is critical for parasite proliferation. Parasit Vectors 2024; 17:105. [PMID: 38439083 PMCID: PMC10910794 DOI: 10.1186/s13071-024-06207-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Accepted: 02/18/2024] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND The human sortilin protein is an important drug target and detection marker for cancer research. The sortilin from Toxoplasma gondii transports proteins associated with the apical organelles of the parasite. In this study, we aimed to determine the intracellular localization and structural domains of T. gondii sortilin, which may mediate protein transportation. Approaches to the functional inhibition of sortilin to establish novel treatments for T. gondii infections were explored. METHODS A gene encoding the sortilin protein was identified in the T. gondii genome. Immunoprecipitation and mass spectrometry were performed to identify the protein species transported by T. gondii sortilin. The interaction of each structural domain of sortilin with the transported proteins was investigated using bio-layer interferometry. The binding regions of the transported proteins in sortilin were identified. The effect of the sortilin inhibitor AF38469 on the infectivity of T. gondii was investigated. The binding site of AF38469 on sortilin was determined. RESULTS The subdomains Vps10, sortilin-C, and sortilin-M of the sortilin were identified as the binding regions for intracellular transportation of the target proteins. The sortilin inhibitor AF38469 bound to the Vps10 structural domain of T. gondii sortilin, which inhibited parasite invasion, replication, and intracellular growth in vitro and was therapeutic in mice infected with T. gondii. CONCLUSION The Vps10, sortilin-C, and sortilin-M subdomains of T. gondii sortilin were identified as functional regions for intracellular protein transport. The binding region for the sortilin inhibitor AF38469 was also identified as the Vps10 subdomain. This study establishes sortilin as a promising drug target against T. gondii and provides a valuable reference for the development of anti-T. gondii drug-target studies.
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Affiliation(s)
- Chenghuan Li
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Ning Jiang
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Yize Liu
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Yiwei Zhang
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Ran Chen
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Ying Feng
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Xiaoyu Sang
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China
| | - Qijun Chen
- Key Laboratory of Livestock Infectious Diseases, Ministry of Education, and Key Laboratory of Ruminant Infectious Disease Prevention and Control (East), Ministry of Agriculture and Rural Affairs, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, 120 Dongling Road, Shenyang, 110866, China.
- Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, 120 Dongling Road, Shenyang, 110866, China.
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Tobeh NS, Bruce KD. Emerging Alzheimer's disease therapeutics: promising insights from lipid metabolism and microglia-focused interventions. Front Aging Neurosci 2023; 15:1259012. [PMID: 38020773 PMCID: PMC10630922 DOI: 10.3389/fnagi.2023.1259012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 10/03/2023] [Indexed: 12/01/2023] Open
Abstract
More than 55 million people suffer from dementia, with this number projected to double every 20 years. In the United States, 1 in 3 aged individuals dies from Alzheimer's disease (AD) or another type of dementia and AD kills more individuals than breast cancer and prostate cancer combined. AD is a complex and multifactorial disease involving amyloid plaque and neurofibrillary tangle formation, glial cell dysfunction, and lipid droplet accumulation (among other pathologies), ultimately leading to neurodegeneration and neuronal death. Unfortunately, the current FDA-approved therapeutics do not reverse nor halt AD. While recently approved amyloid-targeting antibodies can slow AD progression to improve outcomes for some patients, they are associated with adverse side effects, may have a narrow therapeutic window, and are expensive. In this review, we evaluate current and emerging AD therapeutics in preclinical and clinical development and provide insight into emerging strategies that target brain lipid metabolism and microglial function - an approach that may synergistically target multiple mechanisms that drive AD neuropathogenesis. Overall, we evaluate whether these disease-modifying emerging therapeutics hold promise as interventions that may be able to reverse or halt AD progression.
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Affiliation(s)
- Nour S Tobeh
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Kimberley D Bruce
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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Lazniewska J, Li KL, Johnson IRD, Sorvina A, Logan JM, Martini C, Moore C, Ung BSY, Karageorgos L, Hickey SM, Prabhakaran S, Heatlie JK, Brooks RD, Huzzell C, Warnock NI, Ward MP, Mohammed B, Tewari P, Martin C, O'Toole S, Edgerton LB, Bates M, Moretti P, Pitson SM, Selemidis S, Butler LM, O'Leary JJ, Brooks DA. Dynamic interplay between sortilin and syndecan-1 contributes to prostate cancer progression. Sci Rep 2023; 13:13489. [PMID: 37596305 PMCID: PMC10439187 DOI: 10.1038/s41598-023-40347-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 08/09/2023] [Indexed: 08/20/2023] Open
Abstract
Prostate cancer (PCa) development and progression relies on the programming of glucose and lipid metabolism, and this involves alterations in androgen receptor expression and signalling. Defining the molecular mechanism that underpins this metabolic programming will have direct significance for patients with PCa who have a poor prognosis. Here we show that there is a dynamic balance between sortilin and syndecan-1, that reports on different metabolic phenotypes. Using tissue microarrays, we demonstrated by immunohistochemistry that sortilin was highly expressed in low-grade cancer, while syndecan-1 was upregulated in high-grade disease. Mechanistic studies in prostate cell lines revealed that in androgen-sensitive LNCaP cells, sortilin enhanced glucose metabolism by regulating GLUT1 and GLUT4, while binding progranulin and lipoprotein lipase (LPL) to limit lipid metabolism. In contrast, in androgen-insensitive PC3 cells, syndecan-1 was upregulated, interacted with LPL and colocalised with β3 integrin to promote lipid metabolism. In addition, androgen-deprived LNCaP cells had decreased expression of sortilin and reduced glucose-metabolism, but increased syndecan-1 expression, facilitating interactions with LPL and possibly β3 integrin. We report a hitherto unappreciated molecular mechanism for PCa, which may have significance for disease progression and how androgen-deprivation therapy might promote castration-resistant PCa.
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Affiliation(s)
- Joanna Lazniewska
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia.
| | - Ka Lok Li
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Ian R D Johnson
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Alexandra Sorvina
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Jessica M Logan
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Carmela Martini
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Courtney Moore
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Ben S-Y Ung
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Litsa Karageorgos
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Shane M Hickey
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Sarita Prabhakaran
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
- Department of Anatomical Pathology, College of Medicine and Public Health, Flinders University, Bedford Park, SA, 5042, Australia
| | - Jessica K Heatlie
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Robert D Brooks
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Chelsea Huzzell
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Nicholas I Warnock
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, SA, 5000, Australia
| | - Mark P Ward
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | - Bashir Mohammed
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | - Prerna Tewari
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | - Cara Martin
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | - Sharon O'Toole
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | | | - Mark Bates
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | - Paul Moretti
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, SA, 5000, Australia
| | - Stuart M Pitson
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, SA, 5000, Australia
| | - Stavros Selemidis
- School of Health and Biomedical Sciences, STEM College, RMIT University, Bundoora, VIC, 3083, Australia
| | - Lisa M Butler
- South Australian ImmunoGENomics Cancer Institute and Freemasons Centre for Male Health and Wellbeing, University of Adelaide, Adelaide, SA, 5000, Australia
- Solid Tumour Program, Precision Cancer Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, SA, 5000, Australia
| | - John J O'Leary
- Department of Histopathology, Trinity College Dublin, Dublin 8, Ireland
| | - Douglas A Brooks
- Clinical and Health Sciences, University of South Australia, Adelaide, SA, 5000, Australia.
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Wang Y, Luan M, Xue L, Jin J, Xie A. Evaluation of the relationship between SORL1 gene polymorphism and Parkinson's disease in the Chinese population. Neurosci Lett 2022; 778:136602. [DOI: 10.1016/j.neulet.2022.136602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 03/26/2022] [Indexed: 11/29/2022]
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Hoffmann N, Peters J. Functions of the (pro)renin receptor (Atp6ap2) at molecular and system levels: pathological implications in hypertension, renal and brain development, inflammation, and fibrosis. Pharmacol Res 2021; 173:105922. [PMID: 34607004 DOI: 10.1016/j.phrs.2021.105922] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/16/2021] [Accepted: 09/29/2021] [Indexed: 12/13/2022]
Abstract
The (pro)renin receptor [(P)RR, Atp6ap2] was initially discovered as a membrane-bound binding partner of prorenin and renin. A soluble (P)RR has additional paracrine effects and is involved in metabolic syndrome and kidney damage. Meanwhile it is clear that most of the effects of the (P)RR are independent of prorenin. In the kidney, (P)RR plays an important role in renal dysfunction by activating proinflammatory and profibrotic molecules. In the brain, (P)RR is expressed in cardiovascular regulatory nuclei and is linked to hypertension. (P)RR is known to be an essential component of the v-ATPase as a key accessory protein and plays an important role in kidney, brain and heart via regulating the pH of the extracellular space and intracellular compartments. V-ATPase and (P)RR together act on WNT and mTOR signalling pathways, which are responsible for cellular homeostasis and autophagy. (P)RR through its role in v-ATPase assembly and function is also important for fast recycling endocytosis by megalin. In the kidney, megalin together with v-ATPase and (P)RR is crucial for endocytic uptake of components of the RAS and their intracellular processing. In the brain, (P)RR, v-ATPases and megalin are important regulators both during development and in the adult. All three proteins are associated with diseases such as XLMR, XMRE, X-linked parkinsonism and epilepsy, cognitive disorders with Parkinsonism, spasticity, intellectual disability, and Alzheimer's Disease which are characterized by impaired neuronal function and/or neuronal loss. The present review focusses on the relevant effects of Atp6ap2 without assigning them necessarily to the RAS. Mechanistically, many effects can be well explained by the role of Atp6ap2 for v-ATPase assembly and function. Furthermore, application of a soluble (P)RR analogue as new therapeutic option is discussed.
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Affiliation(s)
- Nadin Hoffmann
- Institute of Physiology, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15A, 17475, Greifswald, Germany
| | - Jörg Peters
- Institute of Physiology, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15A, 17475, Greifswald, Germany.
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8
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Martins R, Brito LF, Machado PC, Pinto LFB, Silva MR, Schenkel FS, Pedrosa VB. Genome-wide association study and pathway analysis for carcass fatness in Nellore cattle measured by ultrasound. Anim Genet 2021; 52:730-733. [PMID: 34370325 DOI: 10.1111/age.13129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2021] [Indexed: 12/16/2022]
Abstract
Identifying genes or genomic regions influencing carcass-quality traits such as fatness (FTN) is essential to optimize the genetic selection processes in beef cattle. The aim of this study was to identify genomic regions associated with FTN in Nellore cattle as well as to elucidate the metabolic pathways related to the phenotypic expression. Ultrasound-based measurements of FTN were collected in 11 750 animals, with 39 903 animals in the pedigree file. Additionally, 1440 animals were genotyped using the GGP-indicus 35K SNP panel, which contained 33 623 SNPs after quality control. Twenty genes related to FTN were found on 11 chromosomes, explaining 12.96% of the total additive genetic variance. Gene ontology revealed seven genes: NR1L2, PKD2, GSK3β, EXT1, RAD51B, SORCS1 and DPH6, associated with important processes related to FTN. In addition, novel candidate genes (MAATS1, LYPD1, CDK5RAP2, RAD51B, c13H2Oorf96 and TRAPPC11) were detected and could provide further knowledge to uncover genetic regions associated to carcass fatness in beef cattle.
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Affiliation(s)
- R Martins
- Department of Animal Sciences, State University of Ponta Grossa, Ponta Grossa, PR, 84030-900, Brazil
| | - L F Brito
- Department of Animal Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - P C Machado
- Department of Animal Sciences, State University of Ponta Grossa, Ponta Grossa, PR, 84030-900, Brazil
| | - L F B Pinto
- Department of Animal Sciences, Federal University of Bahia, Av. Adhemar de Barros s/n, Ondina, Salvador, BA, 40170-115, Brazil
| | - M R Silva
- Melhore Animal and Katayama Agropecuaria Lda, Guarapes, SP, 16700-000, Brazil
| | - F S Schenkel
- Animal and Poultry Science Department, Centre for Genetic Improvement of Livestock, University of Guelph, 50 Stone Road East, Guelph, ON, Canada
| | - V B Pedrosa
- Department of Animal Sciences, State University of Ponta Grossa, Ponta Grossa, PR, 84030-900, Brazil
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9
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Martins R, Machado PC, Pinto LFB, Silva MR, Schenkel FS, Brito LF, Pedrosa VB. Genome-wide association study and pathway analysis for fat deposition traits in nellore cattle raised in pasture-based systems. J Anim Breed Genet 2020; 138:360-378. [PMID: 33232564 DOI: 10.1111/jbg.12525] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/30/2020] [Accepted: 11/01/2020] [Indexed: 02/06/2023]
Abstract
Genome-wide association study (GWAS) is a powerful tool to identify candidate genes and genomic regions underlying key biological mechanisms associated with economically important traits. In this context, the aim of this study was to identify genomic regions and metabolic pathways associated with backfat thickness (BFT) and rump fat thickness (RFT) in Nellore cattle, raised in pasture-based systems. Ultrasound-based measurements of BFT and RFT (adjusted to 18 months of age) were collected in 11,750 animals, with 39,903 animals in the pedigree file. Additionally, 1,440 animals were genotyped using the GGP-indicus 35K SNP chip, containing 33,623 SNPs after the quality control. The single-step GWAS analyses were performed using the BLUPF90 family programs. Candidate genes were identified through the Ensembl database incorporated in the BioMart tool, while PANTHER and REVIGO were used to identify the key metabolic pathways and gene networks. A total of 18 genomic regions located on 10 different chromosomes and harbouring 23 candidate genes were identified for BFT. For RFT, 22 genomic regions were found on 14 chromosomes, with a total of 29 candidate genes identified. The results of the pathway analyses showed important genes for BFT, including TBL1XR1, AHCYL2, SLC4A7, AADAT, VPS53, IDH2 and ETS1, which are involved in lipid metabolism, synthesis of cellular amino acids, transport of solutes, transport between Golgi Complex membranes, cell differentiation and cellular development. The main genes identified for RFT were GSK3β, LRP1B, EXT1, GRB2, SORCS1 and SLMAP, which are involved in metabolic pathways such as glycogen synthesis, lipid transport and homeostasis, polysaccharide and carbohydrate metabolism. Polymorphisms located in these candidate genes can be incorporated in commercial genotyping platforms to improve the accuracy of imputation and genomic evaluations for carcass fatness. In addition to uncovering biological mechanisms associated with carcass quality, the key gene pathways identified can also be incorporated in biology-driven genomic prediction methods.
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Affiliation(s)
- Rafaela Martins
- Department of Animal Sciences, State University of Ponta Grossa, Ponta Grossa, Brazil
| | - Pamela C Machado
- Department of Animal Sciences, State University of Ponta Grossa, Ponta Grossa, Brazil
| | | | - Marcio R Silva
- Melhore Animal and Katayama Agropecuaria Lda, Guararapes, Brazil
| | - Flavio S Schenkel
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Luiz F Brito
- Department of Animal Sciences, Purdue University, West Lafayette, IN, USA
| | - Victor B Pedrosa
- Department of Animal Sciences, State University of Ponta Grossa, Ponta Grossa, Brazil
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Proprotein Convertase Subtilisin/Kexin Type 9, Angiopoietin-Like Protein 8, Sortilin, and Cholesteryl Ester Transfer Protein-Friends of Foes for Psoriatic Patients at the Risk of Developing Cardiometabolic Syndrome? Int J Mol Sci 2020; 21:ijms21103682. [PMID: 32456228 PMCID: PMC7279158 DOI: 10.3390/ijms21103682] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/16/2020] [Accepted: 05/21/2020] [Indexed: 12/13/2022] Open
Abstract
Psoriasis is a systemic, immune-metabolic disease with strong genetic predispositions and autoimmune pathogenic traits. During psoriasis progression, a wide spectrum of comorbidities comes into play with the leading role of the cardio-metabolic syndrome (CMS) that occurs with the frequency of 30–50% amongst the psoriatic patients. Both conditions—psoriasis and CMS—have numerous common pathways, mainly related to proinflammatory pathways and cytokine profiles. Surprisingly, despite the years of research, the exact pathways linking the occurrence of CMS in the psoriasis population are still not fully understood. Recently published papers, both clinical and based on the basic science, shed new light into this relationship providing an insight into novel key-players proteins with plausible effects on above-mentioned interplay. Taking into account recent advances in this important medical matter, this review aims to discuss comprehensively the role of four proteins: proprotein convertase subtilisin/kexin type-9 (PSCK9), angiopoietin-like protein 8 (ANGPLT8), sortilin (SORT1), and cholesteryl ester transfer proteins (CEPT) as plausible links between psoriasis and CMS.
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11
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Su X, Peng D. New insight into sortilin in controlling lipid metabolism and the risk of atherogenesis. Biol Rev Camb Philos Soc 2020; 95:232-243. [PMID: 31625271 DOI: 10.1111/brv.12561] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 01/24/2023]
Affiliation(s)
- Xin Su
- Department of Cardiovascular Medicine, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Daoquan Peng
- Department of Cardiovascular Medicine, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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12
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Gu XH, Li H, Zhang L, He T, Chai X, Wei H, Gao DS. Differential expression of glial cell line-derived neurotrophic factor splice variants in the mouse brain. Neural Regen Res 2020; 15:270-276. [PMID: 31552899 PMCID: PMC6905338 DOI: 10.4103/1673-5374.265561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Glial cell line-derived neurotrophic factor (GDNF) plays a critical role in neuronal survival and function. GDNF has two major splice variants in the brain, α-pro-GDNF and β-pro-GDNF, and both isoforms have strong neuroprotective effects on dopamine neurons. However, the expression of the GDNF splice variants in dopaminergic neurons in the brain remains unclear. Therefore, in this study, we investigated the mRNA and protein expression of α- and β-pro-GDNF in the mouse brain by real-time quantitative polymerase chain reaction, using splice variant-specific primers, and western blot analysis. At the mRNA level, β-pro-GDNF expression was significantly greater than that of α-pro-GDNF in the mouse brain. In contrast, at the protein level, α-pro-GDNF expression was markedly greater than that of β-pro-GDNF. To clarify the mechanism underlying this inverse relationship in mRNA and protein expression levels of the GDNF splice variants, we analyzed the expression of sorting protein-related receptor with A-type repeats (SorLA) by real-time quantitative polymerase chain reaction. At the mRNA level, SorLA was positively associated with β-pro-GDNF expression, but not with α-pro-GDNF expression. This suggests that the differential expression of α- and β-pro-GDNF in the mouse brain is related to SorLA expression. As a sorting protein, SorLA could contribute to the inverse relationship among the mRNA and protein levels of the GDNF isoforms. This study was approved by the Animal Ethics Committee of Xuzhou Medical University, China on July 14, 2016.
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Affiliation(s)
- Xiao-He Gu
- Department of Anatomy and Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Heng Li
- Department of Anatomy and Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Lin Zhang
- Department of Anatomy and Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Tao He
- Department of Anatomy and Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Xiang Chai
- Department of Anatomy and Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - He Wei
- Department of Neurosurgery, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Dian-Shuai Gao
- Department of Anatomy and Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
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13
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HSPA12A targets the cytoplasmic domain and affects the trafficking of the Amyloid Precursor Protein receptor SorLA. Sci Rep 2019; 9:611. [PMID: 30679749 PMCID: PMC6345817 DOI: 10.1038/s41598-018-37336-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/30/2018] [Indexed: 01/11/2023] Open
Abstract
SorLA and Sortilin are multifunctional receptors involved in endocytosis and intracellular sorting of different and unrelated ligands. SorLA has recently attracted much attention as a novel strong risk gene for Alzheimer’s disease, and much effort is currently being put into understanding the underlying molecular mechanism. Trafficking of SorLA and Sortilin are mediated by interacting with AP-1, AP-2, GGA 1-3 and the retromer complex. Although these cytosolic adaptor proteins all bind to both SorLA and Sortilin, a large fraction of intracellular Sortilin and SorLA are located in different subcellular vesicles. This indicates that unknown specialised adaptor proteins targeting SorLA for trafficking are yet to be discovered. We have identified HSPA12A as a new adaptor protein that, among Vps10p-D receptors, selectively binds to SorLA in an ADP/ATP dependent manner. This is the first described substrate of HSPA12A, and we demonstrate that the binding, which affects both endocytic speed and subcellular localisation of SorLA, is mediated by specific acidic residues in the cytosolic domain of SorLA. The identification of the relatively unknown HSPA12A as a SorLA specific interaction partner could lead to novel insight into the molecular mechanism of SorLA, and re-emphasises the role of heat shock proteins in neurodegenerative diseases.
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14
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Yabe‐Wada T, Matsuba S, Unno M, Onai N. Crystal structure of the ligand‐free form of the Vps10 ectodomain of dimerized Sortilin at acidic
pH. FEBS Lett 2018; 592:2647-2657. [DOI: 10.1002/1873-3468.13181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/18/2018] [Accepted: 06/29/2018] [Indexed: 12/12/2022]
Affiliation(s)
| | - Shintaro Matsuba
- Department of Immunology Kanazawa Medical University Uchinada Japan
| | - Masaki Unno
- Graduate School of Science and Engineering Ibaraki University Japan
| | - Nobuyuki Onai
- Department of Immunology Kanazawa Medical University Uchinada Japan
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15
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Gao A, Cayabyab FS, Chen X, Yang J, Wang L, Peng T, Lv Y. Implications of Sortilin in Lipid Metabolism and Lipid Disorder Diseases. DNA Cell Biol 2017; 36:1050-1061. [DOI: 10.1089/dna.2017.3853] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Anbo Gao
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang, China
| | - Francisco S. Cayabyab
- Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Xi Chen
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang, China
| | - Jing Yang
- Department of Metabolism & Endocrinology, The First Affiliated Hospital, University of South China, Hengyang, China
| | - Li Wang
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang, China
| | - Tianhong Peng
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang, China
| | - Yuncheng Lv
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang, China
- Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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16
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Januliene D, Manavalan A, Ovesen PL, Pedersen KM, Thirup S, Nykjær A, Moeller A. Hidden Twins: SorCS Neuroreceptors Form Stable Dimers. J Mol Biol 2017; 429:2907-2917. [PMID: 28827148 DOI: 10.1016/j.jmb.2017.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 08/09/2017] [Accepted: 08/11/2017] [Indexed: 11/26/2022]
Abstract
SorCS1, SorCS2 and SorCS3 belong to the Vps10p-domain family of multiligand receptors. Genetic and functional studies have linked SorCS receptors to psychiatric disorders, Alzheimer's disease and type 2 diabetes, demonstrating critical roles in neuronal functionality and metabolic control. Surprisingly, their structural composition has so far not been studied. Here we have characterized SorCS1, SorCS2 and SorCS3 using biochemical methods and electron microscopy. We found that their purified extracellular domains co-exist in stable dimeric and monomeric populations. This was supported by co-immunoprecipitation experiments, where membrane-bound dimers were successfully pulled down from cell lysate. While dimers were virtually unbreakable, dimerization of the monomeric population was promoted through enzymatic deglycosylation. We conclude that post-translational modifications, specifically the degree and pattern of glycosylation, regulate the oligomeric state of the protein. Hence, cells may dictate ligand specificity by controlling the ratio between monomers and dimers and, therefore, regulate the multiple functions of SorCS receptors.
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Affiliation(s)
- Dovile Januliene
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany; DANDRITE, iNANO, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | | | - Peter Lund Ovesen
- DANDRITE, Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus C, Denmark
| | - Karen-Marie Pedersen
- DANDRITE, Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus C, Denmark
| | - Søren Thirup
- MIND Centre, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Anders Nykjær
- Mayo Clinic, 4500 San Pablo Rd S, Jacksonville, FL 32224, USA; DANDRITE, Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus C, Denmark
| | - Arne Moeller
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany; DANDRITE, iNANO, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
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17
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Paththinige CS, Sirisena ND, Dissanayake V. Genetic determinants of inherited susceptibility to hypercholesterolemia - a comprehensive literature review. Lipids Health Dis 2017; 16:103. [PMID: 28577571 PMCID: PMC5457620 DOI: 10.1186/s12944-017-0488-4] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/17/2017] [Indexed: 02/08/2023] Open
Abstract
Hypercholesterolemia is a strong determinant of mortality and morbidity associated with cardiovascular diseases and a major contributor to the global disease burden. Mutations in four genes (LDLR, APOB, PCSK9 and LDLRAP1) account for the majority of cases with familial hypercholesterolemia. However, a substantial proportion of adults with hypercholesterolemia do not have a mutation in any of these four genes. This indicates the probability of having other genes with a causative or contributory role in the pathogenesis of hypercholesterolemia and suggests a polygenic inheritance of this condition. Here in, we review the recent evidence of association of the genetic variants with hypercholesterolemia and the three lipid traits; total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C), their biological pathways and the associated pathogenetic mechanisms. Nearly 80 genes involved in lipid metabolism (encoding structural components of lipoproteins, lipoprotein receptors and related proteins, enzymes, lipid transporters, lipid transfer proteins, and activators or inhibitors of protein function and gene transcription) with single nucleotide variants (SNVs) that are recognized to be associated with hypercholesterolemia and serum lipid traits in genome-wide association studies and candidate gene studies were identified. In addition, genome-wide association studies in different populations have identified SNVs associated with TC, HDL-C and LDL-C in nearly 120 genes within or in the vicinity of the genes that are not known to be involved in lipid metabolism. Over 90% of the SNVs in both these groups are located outside the coding regions of the genes. These findings indicates that there might be a considerable number of unrecognized processes and mechanisms of lipid homeostasis, which when disrupted, would lead to hypercholesterolemia. Knowledge of these molecular pathways will enable the discovery of novel treatment and preventive methods as well as identify the biochemical and molecular markers for the risk prediction and early detection of this common, yet potentially debilitating condition.
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Affiliation(s)
- C S Paththinige
- Human Genetics Unit, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, 00800, Sri Lanka.
| | - N D Sirisena
- Human Genetics Unit, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, 00800, Sri Lanka
| | - Vhw Dissanayake
- Human Genetics Unit, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, 00800, Sri Lanka
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18
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Yabe-Wada T, Matsuba S, Takeda K, Sato T, Suyama M, Ohkawa Y, Takai T, Shi H, Philpott CC, Nakamura A. TLR signals posttranscriptionally regulate the cytokine trafficking mediator sortilin. Sci Rep 2016; 6:26566. [PMID: 27220277 PMCID: PMC4879639 DOI: 10.1038/srep26566] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 05/04/2016] [Indexed: 01/14/2023] Open
Abstract
Regulating the transcription, translation and secretion of cytokines is crucial for controlling the appropriate balance of inflammation. Here we report that the sorting receptor sortilin plays a key role in cytokine production. We observed interactions of sortilin with multiple cytokines including IFN-α, and sortilin depletion in plasmacytoid dendritic cells (pDCs) led to a reduction of IFN-α secretion, suggesting a pivotal role of sortilin in the exocytic trafficking of IFN-α in pDCs. Moreover, sortilin mRNA was degraded posttranscriptionally upon stimulation with various TLR ligands. Poly-rC-binding protein 1 (PCBP1) recognized the C-rich element (CRE) in the 3′ UTR of sortilin mRNA, and depletion of PCBP1 enhanced the degradation of sortilin transcripts, suggesting that PCBP1 can act as a trans-acting factor to stabilize sortilin transcripts. The nucleotide-binding ability of PCBP1 was impaired by zinc ions and alterations of intracellular zinc affect sortilin expression. PCBP1 may therefore control the stability of sortilin transcripts by sensing intracellular zinc levels. Collectively, our findings provide insights into the posttranslational regulation of cytokine production through the posttranscriptional control of sortilin expression by TLR signals.
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Affiliation(s)
- Toshiki Yabe-Wada
- Department of Immunology, Kanazawa Medical University, Kahoku Uchinada, Ishikawa, 920-0293, JAPAN.,Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shintaro Matsuba
- Department of Immunology, Kanazawa Medical University, Kahoku Uchinada, Ishikawa, 920-0293, JAPAN
| | - Kazuya Takeda
- Department of Immunology, Kanazawa Medical University, Kahoku Uchinada, Ishikawa, 920-0293, JAPAN
| | - Tetsuya Sato
- Division of Bioinformatics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Mikita Suyama
- Division of Bioinformatics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasuyuki Ohkawa
- Department of Advanced Medical Initiatives, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
| | - Toshiyuki Takai
- Department of Experimental Immunology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo, Sendai 980-8575, Japan
| | - Haifeng Shi
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Caroline C Philpott
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Akira Nakamura
- Department of Immunology, Kanazawa Medical University, Kahoku Uchinada, Ishikawa, 920-0293, JAPAN
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19
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Nozue T, Hattori H, Ogawa K, Kujiraoka T, Iwasaki T, Michishita I. Effects of Statin Therapy on Plasma Proprotein Convertase Subtilisin/kexin Type 9 and Sortilin Levels in Statin-Naive Patients with Coronary Artery Disease. J Atheroscler Thromb 2016; 23:848-56. [PMID: 26797266 DOI: 10.5551/jat.33407] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
AIM Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of serum low-density lipoprotein (LDL) cholesterol levels, and sortilin is linked to lipoprotein metabolism. Although statin therapy increases PCSK9 levels, effects of this therapy on plasma sortilin levels have not been evaluated. The purpose of the present study was to examine the effects of statins on plasma PCSK9 and sortilin levels, and association of statin-induced increase in PCSK9 levels with sortilin. METHODS Serum lipid levels and plasma PCSK9 and sortilin levels were measured at baseline and 8 months after statin therapy in 90 statin-naive patients with coronary artery disease (CAD). Pitavastatin 4 mg/day was used to treat 44 patients and pravastatin 20 mg/day to treat the remaining 46 patients. RESULTS For both statin groups, significant increases in hetero-dimer PCSK9 levels (pitavastatin: 31%, p<0.0001; pravastatin: 34%, p=0.03) and decreases in sortilin levels (pitavastatin: -8%, p=0.02; pravastatin: -16%, p=0.002) were observed. Although a reduction in LDL cholesterol was greater in the pitavastatin group than in the pravastatin group, no significant differences were observed in percentage changes in hetero-dimer PCSK9 and sortilin levels. A significant positive correlation was observed between percentage changes in hetero-dimer PCSK9 levels and those in sortilin levels (pitavastatin: r=0.359, p=0.02; pravastatin: r=0.276, p=0.06). CONCLUSIONS Use of pitavastatin and pravastatin increased plasma PCSK9 and decreased sortilin levels. Statin-induced increases in PCSK9 were associated with changes in sortilin in statin-naive patients with CAD.
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Affiliation(s)
- Tsuyoshi Nozue
- Division of Cardiology, Department of Internal Medicine, Yokohama Sakae Kyosai Hospital
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20
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LR11/SorLA links triglyceride-rich lipoproteins to risk of developing cardiovascular disease in FH patients. Atherosclerosis 2015; 243:429-37. [DOI: 10.1016/j.atherosclerosis.2015.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 09/22/2015] [Accepted: 10/05/2015] [Indexed: 12/18/2022]
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21
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Lu X, Meima ME, Nelson JK, Sorrentino V, Loregger A, Scheij S, Dekkers DHW, Mulder MT, Demmers JAA, M-Dallinga-Thie G, Zelcer N, Danser AHJ. Identification of the (Pro)renin Receptor as a Novel Regulator of Low-Density Lipoprotein Metabolism. Circ Res 2015; 118:222-9. [PMID: 26582775 DOI: 10.1161/circresaha.115.306799] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 11/18/2015] [Indexed: 01/16/2023]
Abstract
RATIONALE The (pro)renin receptor ([P]RR) interacts with (pro)renin at concentrations that are >1000× higher than observed under (patho)physiological conditions. Recent studies have identified renin-angiotensin system-independent functions for (P)RR related to its association with the vacuolar H(+)-ATPase. OBJECTIVE To uncover renin-angiotensin system-independent functions of the (P)RR. METHODS AND RESULTS We used a proteomics-based approach to purify and identify (P)RR-interacting proteins. This resulted in identification of sortilin-1 (SORT1) as a high-confidence (P)RR-interacting protein, a finding which was confirmed by coimmunoprecipitation of endogenous (P)RR and SORT1. Functionally, silencing (P)RR expression in hepatocytes decreased SORT1 and low-density lipoprotein (LDL) receptor protein abundance and, as a consequence, resulted in severely attenuated cellular LDL uptake. In contrast to LDL, endocytosis of epidermal growth factor or transferrin remained unaffected by silencing of the (P)RR. Importantly, reduction of LDL receptor and SORT1 protein abundance occurred in the absence of changes in their corresponding transcript level. Consistent with a post-transcriptional event, degradation of the LDL receptor induced by (P)RR silencing could be reversed by lysosomotropic agents, such as bafilomycin A1. CONCLUSIONS Our study identifies a renin-angiotensin system-independent function for the (P)RR in the regulation of LDL metabolism by controlling the levels of SORT1 and LDL receptor.
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Affiliation(s)
- Xifeng Lu
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Marcel E Meima
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Jessica K Nelson
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Vincenzo Sorrentino
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Anke Loregger
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Saskia Scheij
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Dick H W Dekkers
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Monique T Mulder
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Jeroen A A Demmers
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Geesje M-Dallinga-Thie
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands
| | - Noam Zelcer
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands.
| | - A H Jan Danser
- From the Astra Zeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Medical Center, Shenzhen University, Shenzhen, China (X.L.); Division of Pharmacology and Vascular Medicine, Department of Internal Medicine (X.L., M.E.M., M.T.M., A.H.J.D.) and Proteomics Center (D.H.W.D., J.A.A.D.), Erasmus Medical Center, Rotterdam, The Netherlands; and Department of Medical Biochemistry (X.L., J.K.N., V.S., A.L., S.S., N.Z.) and Laboratory of Experimental Vascular Medicine (G.M.D-.T.), Academic Medical Center, Amsterdam, The Netherlands.
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22
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Besharat S, Katoonizadeh A, Moossavi S, Darvishi Z, Roshandel G, Poustchi H, Mohamadkhani A. The possible impact of sortilin in reducing HBsAg expression in chronic hepatitis B. J Med Virol 2015; 88:647-52. [PMID: 26331452 DOI: 10.1002/jmv.24367] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2015] [Indexed: 12/12/2022]
Abstract
Hepatitis B virus (HBV) infection is a major global health problem. Chronically infected people are at risk for progressive hepatic fibrosis and consequent cirrhosis. Hepatitis B surface antigen (HBsAg) level in serum is a complementary marker for intrahepatic HBV DNA and covalently closed circular DNA (cccDNA). Sortilin-1 (SORT1) has been reported to be involved in the post-Golgi vesicle trafficking of Apo lipoproteins degradation pathways. This study was designed to evaluate the hepatic and serum expression of HBsAg and its association with hepatic SORT1 gene expression in patients with chronic HBV. Thirty chronic hepatitis B patients with histological examination results were enrolled in this study. Liver biopsies were analyzed for hepatic HBsAg and SORT1 gene expression by immunohistochemistry and quantitative real time PCR (qRT-PCR), respectively. Twenty seven out of 30 (90%) liver biopsies had positive staining for HBsAg and showed a significant inverse association with hepatic SORT1 fold change gene expression (β = -0.5, P = 0.042). There was significant association between HBV DNA levels and HBsAg expression in hepatocyte or serum titer of HBsAg (r = 0.39, P = 0.029; r = 0.39, P = 0.032 respectively). Serum ALT was also correlated with hepatic activity index (HAI) score (β = 0.6, P = 0.001). Inverse association between hepatic SORT1 gene expression and hepatic HBsAg expression indicates the possible role of sortilin in HBsAg particle formation.
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Affiliation(s)
- Sima Besharat
- Liver and Pancreatobiliary Diseases Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran.,Golestan Research Center of Gastroentrology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran
| | - Aezam Katoonizadeh
- Liver and Pancreatobiliary Diseases Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Shirin Moossavi
- Liver and Pancreatobiliary Diseases Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Gholamreza Roshandel
- Golestan Research Center of Gastroentrology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran
| | - Hossein Poustchi
- Liver and Pancreatobiliary Diseases Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ashraf Mohamadkhani
- Liver and Pancreatobiliary Diseases Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran
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Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
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Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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24
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Habtemichael EN, Alcázar-Román A, Rubin BR, Grossi LR, Belman JP, Julca O, Löffler MG, Li H, Chi NW, Samuel VT, Bogan JS. Coordinated Regulation of Vasopressin Inactivation and Glucose Uptake by Action of TUG Protein in Muscle. J Biol Chem 2015; 290:14454-61. [PMID: 25944897 DOI: 10.1074/jbc.c115.639203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Indexed: 01/16/2023] Open
Abstract
In adipose and muscle cells, insulin stimulates the exocytic translocation of vesicles containing GLUT4, a glucose transporter, and insulin-regulated aminopeptidase (IRAP), a transmembrane aminopeptidase. A substrate of IRAP is vasopressin, which controls water homeostasis. The physiological importance of IRAP translocation to inactivate vasopressin remains uncertain. We previously showed that in skeletal muscle, insulin stimulates proteolytic processing of the GLUT4 retention protein, TUG, to promote GLUT4 translocation and glucose uptake. Here we show that TUG proteolysis also controls IRAP targeting and regulates vasopressin action in vivo. Transgenic mice with constitutive TUG proteolysis in muscle consumed much more water than wild-type control mice. The transgenic mice lost more body weight during water restriction, and the abundance of renal AQP2 water channels was reduced, implying that vasopressin activity is decreased. To compensate for accelerated vasopressin degradation, vasopressin secretion was increased, as assessed by the cosecreted protein copeptin. IRAP abundance was increased in T-tubule fractions of fasting transgenic mice, when compared with controls. Recombinant IRAP bound to TUG, and this interaction was mapped to a short peptide in IRAP that was previously shown to be critical for GLUT4 intracellular retention. In cultured 3T3-L1 adipocytes, IRAP was present in TUG-bound membranes and was released by insulin stimulation. Together with previous results, these data support a model in which TUG controls vesicle translocation by interacting with IRAP as well as GLUT4. Furthermore, the effect of IRAP to reduce vasopressin activity is a physiologically important consequence of vesicle translocation, which is coordinated with the stimulation of glucose uptake.
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Affiliation(s)
| | - Abel Alcázar-Román
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and
| | - Bradley R Rubin
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Laura R Grossi
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Jonathan P Belman
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Omar Julca
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Michael G Löffler
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and
| | - Hongjie Li
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and
| | - Nai-Wen Chi
- the Veterans Affairs San Diego Healthcare System and Department of Medicine, University of California, San Diego, California 92093, and
| | - Varman T Samuel
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and the Veterans Affairs Medical Center, West Haven, Connecticut 06516
| | - Jonathan S Bogan
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020,
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25
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Affiliation(s)
- Marit Westerterp
- From the Division of Molecular Medicine, Department of Medicine, Columbia University, New York.
| | - Alan R Tall
- From the Division of Molecular Medicine, Department of Medicine, Columbia University, New York
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26
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Giammanco A, Cefalù AB, Noto D, Averna MR. The pathophysiology of intestinal lipoprotein production. Front Physiol 2015; 6:61. [PMID: 25852563 PMCID: PMC4367171 DOI: 10.3389/fphys.2015.00061] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/14/2015] [Indexed: 12/12/2022] Open
Abstract
Intestinal lipoprotein production is a multistep process, essential for the absorption of dietary fats and fat-soluble vitamins. Chylomicron assembly begins in the endoplasmic reticulum with the formation of primordial, phospholipids-rich particles that are then transported to the Golgi for secretion. Several classes of transporters play a role in the selective uptake and/or export of lipids through the villus enterocytes. Once secreted in the lymph stream, triglyceride-rich lipoproteins (TRLs) are metabolized by Lipoprotein lipase (LPL), which catalyzes the hydrolysis of triacylglycerols of very low density lipoproteins (VLDLs) and chylomicrons, thereby delivering free fatty acids to various tissues. Genetic mutations in the genes codifying for these proteins are responsible of different inherited disorders affecting chylomicron metabolism. This review focuses on the molecular pathways that modulate the uptake and the transport of lipoproteins of intestinal origin and it will highlight recent findings on TRLs assembly.
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Affiliation(s)
| | | | | | - Maurizio R. Averna
- Dipartimento Biomedico di Medicina Interna e Specialistica, Università degli Studi di PalermoPalermo, Italy
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27
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Abstract
PURPOSE OF REVIEW Genome-wide association studies have been used as an unbiased tool to identify novel genes that contribute to variations in LDL cholesterol levels in the hopes of uncovering new biology and new therapeutic targets for the treatment of atherosclerotic cardiovascular disease. The locus identified by genome-wide association studies with the strongest association with LDL cholesterol and atherosclerotic cardiovascular disease is the 1p13 sortilin-1 (SORT1) locus. Here, we review the identification and characterization of this locus, the initial physiological studies describing the role of SORT1 in lipoprotein metabolism, and recent work that has begun to sort out the complexity of this role. RECENT FINDINGS Studies by several groups support an important role for sortilin in lipoprotein metabolism; however, the directionality of the effect of sortilin on plasma cholesterol and its role in the secretion of hepatic lipoproteins remains controversial. Studies by several groups support a role for sortilin in inhibiting lipoprotein export, whereas other studies suggest that sortilin facilitates lipoprotein export. SUMMARY Understanding the mechanism by which sortilin affects LDL cholesterol will increase our understanding of the regulation of lipoprotein metabolism and hepatic lipoprotein export and may also allow us to harness the power of the 1p13 SORT1 locus for the treatment of atherosclerotic cardiovascular disease.
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Affiliation(s)
- Alanna Strong
- Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
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28
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Kebede MA, Oler AT, Gregg T, Balloon AJ, Johnson A, Mitok K, Rabaglia M, Schueler K, Stapleton D, Thorstenson C, Wrighton L, Floyd BJ, Richards O, Raines S, Eliceiri K, Seidah NG, Rhodes C, Keller MP, Coon JL, Audhya A, Attie AD. SORCS1 is necessary for normal insulin secretory granule biogenesis in metabolically stressed β cells. J Clin Invest 2014; 124:4240-56. [PMID: 25157818 DOI: 10.1172/jci74072] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 07/14/2014] [Indexed: 01/21/2023] Open
Abstract
We previously positionally cloned Sorcs1 as a diabetes quantitative trait locus. Sorcs1 belongs to the Vacuolar protein sorting-10 (Vps10) gene family. In yeast, Vps10 transports enzymes from the trans-Golgi network (TGN) to the vacuole. Whole-body Sorcs1 KO mice, when made obese with the leptin(ob) mutation (ob/ob), developed diabetes. β Cells from these mice had a severe deficiency of secretory granules (SGs) and insulin. Interestingly, a single secretagogue challenge failed to consistently elicit an insulin secretory dysfunction. However, multiple challenges of the Sorcs1 KO ob/ob islets consistently revealed an insulin secretion defect. The luminal domain of SORCS1 (Lum-Sorcs1), when expressed in a β cell line, acted as a dominant-negative, leading to SG and insulin deficiency. Using syncollin-dsRed5TIMER adenovirus, we found that the loss of Sorcs1 function greatly impairs the rapid replenishment of SGs following secretagogue challenge. Chronic exposure of islets from lean Sorcs1 KO mice to high glucose and palmitate depleted insulin content and evoked an insulin secretion defect. Thus, in metabolically stressed mice, Sorcs1 is important for SG replenishment, and under chronic challenge by insulin secretagogues, loss of Sorcs1 leads to diabetes. Overexpression of full-length SORCS1 led to a 2-fold increase in SG content, suggesting that SORCS1 is sufficient to promote SG biogenesis.
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29
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Fisher E, Lake E, McLeod RS. Apolipoprotein B100 quality control and the regulation of hepatic very low density lipoprotein secretion. J Biomed Res 2014; 28:178-93. [PMID: 25013401 PMCID: PMC4085555 DOI: 10.7555/jbr.28.20140019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/15/2014] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein B (apoB) is the main protein component of very low density lipoprotein (VLDL) and is necessary for the assembly and secretion of these triglyceride (TG)-rich particles. Following release from the liver, VLDL is converted to low density lipoprotein (LDL) in the plasma and increased production of VLDL can therefore play a detrimental role in cardiovascular disease. Increasing evidence has helped to establish VLDL assembly as a target for the treatment of dyslipidemias. Multiple factors are involved in the folding of the apoB protein and the formation of a secretion-competent VLDL particle. Failed VLDL assembly can initiate quality control mechanisms in the hepatocyte that target apoB for degradation. ApoB is a substrate for endoplasmic reticulum associated degradation (ERAD) by the ubiquitin proteasome system and for autophagy. Efficient targeting and disposal of apoB is a regulated process that modulates VLDL secretion and partitioning of TG. Emerging evidence suggests that significant overlap exists between these degradative pathways. For example, the insulin-mediated targeting of apoB to autophagy and postprandial activation of the unfolded protein response (UPR) may employ the same cellular machinery and regulatory cues. Changes in the quality control mechanisms for apoB impact hepatic physiology and pathology states, including insulin resistance and fatty liver. Insulin signaling, lipid metabolism and the hepatic UPR may impact VLDL production, particularly during the postprandial state. In this review we summarize our current understanding of VLDL assembly, apoB degradation, quality control mechanisms and the role of these processes in liver physiology and in pathologic states.
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Affiliation(s)
- Eric Fisher
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Elizabeth Lake
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Roger S McLeod
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
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30
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The hypercholesterolemia-risk gene SORT1 facilitates PCSK9 secretion. Cell Metab 2014; 19:310-8. [PMID: 24506872 DOI: 10.1016/j.cmet.2013.12.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/02/2013] [Accepted: 12/12/2013] [Indexed: 12/23/2022]
Abstract
Circulating PCSK9 destines low-density lipoprotein receptor for degradation in lysosomes, resulting in increased LDL cholesterol. Accordingly, it is an attractive drug target for hypercholesterolemia, and results from clinical trials are promising. While the physiological role of PCSK9 in cholesterol metabolism is well described, its complex mechanism of action remains poorly understood, although it is known to depend on intracellular trafficking. We here identify sortilin, encoded by the hypercholesterolemia-risk gene SORT1, as a high-affinity sorting receptor for PCSK9. Sortilin colocalizes with PCSK9 in the trans-Golgi network and facilitates its secretion from primary hepatocytes. Accordingly, sortilin-deficient mice display decreased levels of circulating PCSK9, while sortilin overexpression in the liver confers increased plasma PCSK9. Furthermore, circulating PCSK9 and sortilin were positively correlated in a human cohort of healthy individuals, suggesting that sortilin is involved in PCSK9 secretion in humans. Taken together, our findings establish sortilin as a critical regulator of PCSK9 activity.
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Abstract
The sortilin family of Vps10p-domain receptors includes sortilin, SorLA, and SorCS1-3. These type-I transmembrane receptors predominate in distinct neuronal tissues, but expression is also present in certain specialized non-neuronal cell populations including hepatocytes and cells of the immune system. The biology of sortilins is complex as they participate in both cell signaling and in intracellular protein sorting. Sortilins function physiologically in signaling by pro- and mature neurotrophins in neuronal viability and functionality. Recent genome-wide association studies have linked members to neurological disorders such as Alzheimer's disease and bipolar disorder and outside the nervous system to development of coronary artery disease and type-2 diabetes. Particularly well described are the receptor functions in neuronal signaling by pro- (proNT) and mature (NT) neurotrophins and in the processing/metabolism of amyloid precursor protein (APP).
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Affiliation(s)
- S Glerup
- Danish Research Institute of Translational Neuroscience DANDRITE, Nordic EMBL Partnership, and The Lundbeck Foundation Research Center MIND, Department of Biomedicine, University of Aarhus, Ole Worms Allé 3, 8000, Aarhus C, Denmark
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Pieper-Fürst U, Lammert F. Low-density lipoprotein receptors in liver: old acquaintances and a newcomer. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1191-8. [PMID: 24046859 DOI: 10.1016/j.bbalip.2013.03.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The lipoprotein receptors low-density lipoprotein receptor (LDLR), the low-density lipoprotein receptor-related protein 1 (LRP1) and megalin/LRP2 share characteristic structural elements. In addition to their well-known roles in endocytosis of lipoproteins and systemic lipid homeostasis, it has been established that LRP1 mediates the endocytotic clearance of a multitude of extracellular ligands and regulates diverse signaling processes such as growth factor signaling, inflammatory signaling pathways, apoptosis, and phagocytosis in liver. Here, possible functions of LRP1 expression in hepatocytes and non-parenchymal cells in healthy and injured liver are discussed. Recent studies indicate the expression of megalin (LRP2) by hepatic stellate cells, myofibroblasts and Kupffer cells and hypothesize that LRP2 might represent another potential regulator of hepatic inflammatory processes. These observations provide the experimental framework for the systematic and dynamic analysis of the LDLR family during chronic liver injury and fibrogenesis.
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Abstract
In the brain, apolipoprotein E (APOE) delivers cholesterol-rich lipoproteins to neurons to support synaptogenesis and maintenance of synaptic connections. Three APOE alleles exist in the human population with ε4 being an Alzheimer disease (AD) risk gene and ε2 being protective relative to the common ε3 variant. Many hypotheses have been advanced concerning allele-specific effects of APOE on neurodegeneration including effects on Aβ clearance, synaptic transmission, or neurotoxicity. Central to most proposed APOE functions is its interaction with receptors that mediate cellular uptake of this ligand. Several members of the LDL receptor gene family have been implicated as APOE receptors in the (patho)physiology of APOE in the brain, yet their specific modes of action in AD remain controversial. Recently, the pro-neurotrophin receptor sortilin has been identified as a novel APOE receptor in neurons. Ablation of sortilin expression in mice results in accumulation of APOE and Aβ in the brain. Moreover, primary neurons lacking sortilin exhibit significantly impaired uptake of APOE/Aβ complexes. Despite increased brain APOE levels, sortilin-deficient animals recapitulate anomalies in brain lipid homeostasis seen in APOE null mice, indicating functional deficiency in APOE uptake pathways. Taken together, these findings suggest a link between Aβ catabolism and pro-neurotrophin signaling converging on this receptor pathway.
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Abstract
PURPOSE OF REVIEW Since 2007, genome-wide association studies (GWAS) have led to the identification of numerous loci of atherosclerotic cardiovascular disease. The majority of these loci harbor genes previously not known to be involved in atherogenesis. In this review, we summarize the recent progress in understanding the pathophysiology of genetic variants in atherosclerosis. RECENT FINDINGS Fifty-eight loci with P < 10⁻⁷ have been identified in GWAS for coronary heart disease and myocardial infarction. Of these, 23 loci (40%) overlap with GWAS loci of classical risk factors such as lipids, blood pressure, and diabetes mellitus, suggesting a potential causal relation. The vast majority of the remaining 35 loci (60%) are at genomic regions where the mechanism in atherogenesis is unclear. Loci most frequently found in independent GWAS were at Chr9p21.3 (ANRIL/CDKN2B-AS1), Chr6p24.1 (PHACTR1), and Chr1p13.3 (CELSR2, PSRC1, MYBPHL, SORT1). Recent work suggests that Chr9p21.3 exerts its effects through epigenetic regulation of target genes, whereas mechanisms at Chr6p24.1 remain obscure, and Chr1p13.3 affects plasma LDL cholesterol. SUMMARY Novel GWAS loci indicate that our understanding of atherosclerosis is limited and implicate a role of hitherto unknown mechanisms, such as epigenetic gene regulation in atherogenesis.
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Affiliation(s)
- Lesca M Holdt
- Institute of Laboratory Medicine, University Hospital Munich-LMU and Ludwig-Maximilians-University Munich, Munich, Germany
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35
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Mendoza-Barberá E, Julve J, Nilsson SK, Lookene A, Martín-Campos JM, Roig R, Lechuga-Sancho AM, Sloan JH, Fuentes-Prior P, Blanco-Vaca F. Structural and functional analysis of APOA5 mutations identified in patients with severe hypertriglyceridemia. J Lipid Res 2013; 54:649-661. [PMID: 23307945 DOI: 10.1194/jlr.m031195] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
During the diagnosis of three unrelated patients with severe hypertriglyceridemia, three APOA5 mutations [p.(Ser232_Leu235)del, p.Leu253Pro, and p.Asp332ValfsX4] were found without evidence of concomitant LPL, APOC2, or GPIHBP1 mutations. The molecular mechanisms by which APOA5 mutations result in severe hypertriglyceridemia remain poorly understood, and the functional impairment/s induced by these specific mutations was not obvious. Therefore, we performed a thorough structural and functional analysis that included follow-up of patients and their closest relatives, measurement of apoA-V serum concentrations, and sequencing of the APOA5 gene in 200 nonhyperlipidemic controls. Further, we cloned, overexpressed, and purified both wild-type and mutant apoA-V variants and characterized their capacity to activate LPL. The interactions of recombinant wild-type and mutated apoA-V variants with liposomes of different composition, heparin, LRP1, sortilin, and SorLA/LR11 were also analyzed. Finally, to explore the possible structural consequences of these mutations, we developed a three-dimensional model of full-length, lipid-free human apoA-V. A complex, wide array of impairments was found in each of the three mutants, suggesting that the specific residues affected are critical structural determinants for apoA-V function in lipoprotein metabolism and, therefore, that these APOA5 mutations are a direct cause of hypertriglyceridemia.
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Affiliation(s)
| | - Josep Julve
- Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, 08017 Barcelona, Spain
| | - Stefan K Nilsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE90187, Sweden
| | - Aivar Lookene
- Department of Chemistry, Tallinn Technical University, Tallinn 12618, Estonia
| | | | - Rosa Roig
- Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain
| | | | | | | | - Francisco Blanco-Vaca
- Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, 08017 Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08025 Barcelona, Spain
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Vps10 family proteins and the retromer complex in aging-related neurodegeneration and diabetes. J Neurosci 2013; 32:14080-6. [PMID: 23055476 DOI: 10.1523/jneurosci.3359-12.2012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Members of the vacuolar protein sorting 10 (Vps10) family of receptors (including sortilin, SorL1, SorCS1, SorCS2, and SorCS3) play pleiotropic functions in protein trafficking and intracellular and intercellular signaling in neuronal and non-neuronal cells. Interactions have been documented between Vps10 family members and the retromer coat complex, a key component of the intracellular trafficking apparatus that sorts cargo from the early endosome to the trans-Golgi network. In recent years, genes encoding several members of the Vps10 family of proteins, as well as components of the retromer coat complex, have been implicated as genetic risk factors for sporadic and autosomal dominant forms of neurodegenerative diseases, including Alzheimer's disease, frontotemporal lobar degeneration, and Parkinson's disease, with risk for type 2 diabetes mellitus and atherosclerosis. In addition to their functions in protein trafficking, the Vps10 family proteins modulate neurotrophic signaling pathways. Sortilin can impact the intracellular response to brain-derived neurotrophic factor (BDNF) by regulating anterograde trafficking of Trk receptors to the synapse and direct control of BDNF levels, while both sortilin and SorCS2 function as cell surface receptors to mediate acute responses to proneurotrophins. This mini-review and symposium will highlight the emerging data from this rapidly growing area of research implicating the Vps10 family of receptors and the retromer in physiological intracellular trafficking signaling by neurotrophins and in the pathogenesis of neurodegeneration.
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Tveten K, Strøm TB, Cameron J, Berge KE, Leren TP. Mutations in the SORT1 gene are unlikely to cause autosomal dominant hypercholesterolemia. Atherosclerosis 2012; 225:370-5. [PMID: 23102784 DOI: 10.1016/j.atherosclerosis.2012.10.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 09/25/2012] [Accepted: 10/01/2012] [Indexed: 12/18/2022]
Abstract
OBJECTIVE To study whether mutations in the SORT1 gene could be a cause of autosomal dominant hypercholesterolemia and to study the effect of sortilin on the binding and internalization of low density lipoprotein (LDL). METHODS 842 unrelated hypercholesterolemic subjects without mutations in genes known to cause autosomal dominant hypercholesterolemia, were screened for mutations in the SORT1 gene by DNA sequencing. Transfections of wild-type or mutant SORT1 plasmids in HeLa T-REx cells and the use of siRNA were used to study the effect of sortilin on the number of cell-surface LDL receptors and on the binding and internalization of LDL. RESULTS A total of 45 mutations in the SORT1 gene were identified of which 15 were missense mutations. Eight of these were selected for in vitro studies, of which none had a major impact on the amount of LDL bound to the cell surface. There was a positive correlation between the amount of sortilin on the cell surface and the amount of LDL bound. The observation that a mutant sortilin which is predominantly found on the cell surface rather than in post-Golgi compartments, bound very high amounts of LDL, indicates that sortilin does not increase the binding of LDL through an intracellular mechanism. Rather, our data indicate that sortilin binds LDL on the cell surface. CONCLUSION Even though sortilin binds and internalizes LDL by receptor-mediated endocytosis, mutations in the SORT1 gene are unlikely to cause autosomal dominant hypercholesterolemia and may only have a marginal effect on plasma LDL cholesterol levels.
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Affiliation(s)
- Kristian Tveten
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital Rikshospitalet, Oslo, Norway
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The endosomal protein-sorting receptor sortilin has a role in trafficking α-1 antitrypsin. Genetics 2012; 192:889-903. [PMID: 22923381 DOI: 10.1534/genetics.112.143487] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Up to 1 in 3000 individuals in the United States have α-1 antitrypsin deficiency, and the most common cause of this disease is homozygosity for the antitrypsin-Z variant (ATZ). ATZ is inefficiently secreted, resulting in protein deficiency in the lungs and toxic polymer accumulation in the liver. However, only a subset of patients suffer from liver disease, suggesting that genetic factors predispose individuals to liver disease. To identify candidate factors, we developed a yeast ATZ expression system that recapitulates key features of the disease-causing protein. We then adapted this system to screen the yeast deletion mutant collection to identify conserved genes that affect ATZ secretion and thus may modify the risk for developing liver disease. The results of the screen and associated assays indicate that ATZ is degraded in the vacuole after being routed from the Golgi. In fact, one of the strongest hits from our screen was Vps10, which can serve as a receptor for the delivery of aberrant proteins to the vacuole. Because genome-wide association studies implicate the human Vps10 homolog, sortilin, in cardiovascular disease, and because hepatic cell lines that stably express wild-type or mutant sortilin were recently established, we examined whether ATZ levels and secretion are affected by sortilin. As hypothesized, sortilin function impacts the levels of secreted ATZ in mammalian cells. This study represents the first genome-wide screen for factors that modulate ATZ secretion and has led to the identification of a gene that may modify disease severity or presentation in individuals with ATZ-associated liver disease.
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Abstract
Severe hypertriglyceridemia is associated with acute pancreatitis and can be a manifestation of lipoprotein lipase (LPL) deficiency. It is associated with a spectrum of disorders, ranging from heterozygous LPL deficiency allied with environmental factors to rare severe cases of homozygous LPL deficiency. The genes associated with reduced LPL activity include LPL, its cofactor apoC-2, a controlling protein apoA-5 and the LPL receptor GPI-HBP1. The effects of mutations are exacerbated by environmental factors such as diet, pregnancy and insulin resistance. Treatment of clinical LPL deficiency is by ultra-low-fat diet along with the use of fibrates, omega-3 fatty acids, niacin, statins and insulin-sensitizing therapies, depending on the extent of residual LPL activity. Novel therapies that target lipoprotein particle assembly through the antisense oligonucleotides or by interference with triglyceride-loading microsomal transport protein inhibitors offer new potential options for treating hypertriglyceridemia.
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Affiliation(s)
- Adie Viljoen
- Lister Hospital, Stevenage, Hertfordshire, SG1 4AB, UK
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Sparks JD, Sparks CE, Adeli K. Selective hepatic insulin resistance, VLDL overproduction, and hypertriglyceridemia. Arterioscler Thromb Vasc Biol 2012; 32:2104-12. [PMID: 22796579 DOI: 10.1161/atvbaha.111.241463] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Insulin plays a central role in regulating energy metabolism, including hepatic transport of very low-density lipoprotein (VLDL)-associated triglyceride. Hepatic hypersecretion of VLDL and consequent hypertriglyceridemia leads to lower circulating high-density lipoprotein levels and generation of small dense low-density lipoproteins characteristic of the dyslipidemia commonly observed in metabolic syndrome and type 2 diabetes mellitus. Physiological fluctuations of insulin modulate VLDL secretion, and insulin inhibition of VLDL secretion upon feeding may be the first pathway to become resistant in obesity that leads to VLDL hypersecretion. This review summarizes the role of insulin-related signaling pathways that determine hepatic VLDL production. Disruption in signaling pathways that reduce generation of the second messenger phosphatidylinositide (3,4,5) triphosphate downstream of activated phosphatidylinositide 3-kinase underlies the development of VLDL hypersecretion. As insulin resistance progresses, a number of pathways are altered that further augment VLDL hypersecretion, including hepatic inflammatory pathways. Insulin plays a complex role in regulating glucose metabolism, and it is not surprising that the role of insulin in VLDL and lipid metabolism will prove equally complex.
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Affiliation(s)
- Janet D Sparks
- University of Rochester Medical Center, Department of Pathology and Laboratory Medicine, Rochester, NY, USA
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Abstract
Lipoprotein lipase (LPL) is rate limiting in the provision of triglyceride-rich lipoprotein-derived lipids into tissues. LPL is also present in the brain, where its function has remained elusive. Recent evidence implicates a role of LPL in the brain in two processes: (a) the regulation of energy balance and body weight and (b) cognition. Mice with neuron-specific deletion of LPL have increases in food intake that lead to obesity, and then reductions in energy expenditure that further contribute to and sustain the phenotype. In other mice with LPL deficiency rescued from neonatal lethality by somatic gene transfer wherein LPL in the brain remains absent, altered cognition ensues. Taking into consideration data that associate LPL mutations with Alzheimer's disease, a role for LPL in learning and memory seems likely. Overall, the time is ripe for new insights into how LPL-mediated lipoprotein metabolism in the brain impacts CNS processes and systems biology.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, School of Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA.
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Abstract
To enhance glucose uptake into muscle and fat cells, insulin stimulates the translocation of GLUT4 glucose transporters from intracellular membranes to the cell surface. This response requires the intersection of insulin signaling and vesicle trafficking pathways, and it is compromised in the setting of overnutrition to cause insulin resistance. Insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases and through the Rho GTPase TC10α to act on other targets. In unstimulated cells, GLUT4 is incorporated into specialized storage vesicles containing IRAP, LRP1, sortilin, and VAMP2, which are sequestered by TUG, Ubc9, and other proteins. Insulin mobilizes these vesicles directly to the plasma membrane, and it modulates the trafficking itinerary so that cargo recycles from endosomes during ongoing insulin exposure. Knowledge of how signaling and trafficking pathways are coordinated will be essential to understanding the pathogenesis of diabetes and the metabolic syndrome and may also inform a wide range of other physiologies.
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Affiliation(s)
- Jonathan S Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA.
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Current world literature. Curr Opin Lipidol 2012; 23:156-63. [PMID: 22418573 DOI: 10.1097/mol.0b013e3283521229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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