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Liu S, Chen T, Chen B, Liu Y, Lu X, Li J. Lrpap1 deficiency leads to myopia through TGF-β-induced apoptosis in zebrafish. Cell Commun Signal 2022; 20:162. [PMID: 36261846 PMCID: PMC9580148 DOI: 10.1186/s12964-022-00970-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 09/03/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Frameshift mutations in LRPAP1 are responsible for autosomal recessive high myopia in human beings but its underlying mechanism remains elusive. This study aims to investigate the effect of LRPAP1 defect on ocular refractive development and its involved mechanism. METHODS A lrpap1 mutant zebrafish line with homozygous frameshift mutation was generated by CRISPR/Cas9 technology and confirmed by Sanger sequencing. The ocular refractive phenotype was analyzed by calculating the relative refractive error (RRE) with vivo photography and histological analysis at different development stages, together with examining ocular structure change via transmission electron microscopy. Further, RNA sequencing and bioinformatics analysis were performed. The potentially involved signaling pathway as well as the interacted protein were investigated in vivo. RESULTS The lrpap1 homozygous mutant zebrafish line showed myopic phenotype. Specifically, the mutant lines showed larger eye axial length-to-body length in one-month old individuals and a myopic shift with an RRE that changed after two months. Collagen fibers became thinning and disordered in the sclera. Further, RNA sequencing and bioinformatics analysis indicated that apoptosis signaling was activated in mutant line; this was further confirmed by acridine orange and TUNEL staining. Moreover, the expression of TGF-β protein was elevated in the mutant lines. Finally, the treatment of wild-type embryos with a TGF-β agonist aggravated the degree of eyeball apoptosis; conversely, the use of a TGF-β inhibitor mitigated apoptosis in mutant embryos. CONCLUSION The study provides functional evidence of a link between lrpap1 and myopia, suggesting that lrpap1 deficiency could lead to myopia through TGF-β-induced apoptosis signaling. Video abstract.
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Affiliation(s)
- Shanshan Liu
- grid.284723.80000 0000 8877 7471Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Ting Chen
- grid.284723.80000 0000 8877 7471Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Binghao Chen
- grid.459579.30000 0004 0625 057XDepartment of Orthopedics, Guangdong Women and Children Hospital, Guangzhou, China
| | - Yijun Liu
- grid.413107.0Department of Foot and Ankle Surgery, Center for Orthopedic Surgery, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Xiaohe Lu
- grid.284723.80000 0000 8877 7471Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jiali Li
- grid.284723.80000 0000 8877 7471Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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2
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Elsakka EGE, Mokhtar MM, Hegazy M, Ismail A, Doghish AS. Megalin, a multi-ligand endocytic receptor, and its participation in renal function and diseases: A review. Life Sci 2022; 308:120923. [PMID: 36049529 DOI: 10.1016/j.lfs.2022.120923] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/13/2022] [Accepted: 08/26/2022] [Indexed: 11/16/2022]
Abstract
The endocytosis mechanism is a complicated system that is essential for cell signaling and survival. Megalin, a membrane-associated endocytic receptor, and its related proteins such as cubilin, the neonatal Fc receptor for IgG, and NaPi-IIa are important in receptors-mediated endocytosis. Physiologically, megalin uptakes plasma vitamins and proteins from primary urine, preventing their loss. It also facilitates tubular retrieval of solutes and endogenous components that may be involved in modulation and recovery from kidney injuries. Moreover, megalin is responsible for endocytosis of xenobiotics and drugs in renal tubules, increasing their half-life and/or their toxicity. Fluctuations in megalin expression and/or functionality due to changes in its regulatory mechanisms are associated with some sort of kidney injury. Also, it's an important component of several pathological conditions, including diabetic nephropathy and Dent disease. Thus, exploring the fundamental role of megalin in the kidney might help in the protection and/or treatment of multiple kidney-related diseases. Hence, this review aimed to explore the physiological roles of megalin in the kidney and their implications for kidney-related injuries.
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Affiliation(s)
- Elsayed G E Elsakka
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City 11231, Cairo, Egypt.
| | - Mahmoud Mohamed Mokhtar
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City 11231, Cairo, Egypt
| | - Maghawry Hegazy
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City 11231, Cairo, Egypt
| | - Ahmed Ismail
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City 11231, Cairo, Egypt
| | - Ahmed S Doghish
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt.
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3
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The B-cell Receptor Autoantigen LRPAP1 Can Replace Variable Antibody Regions to Target Mantle Cell Lymphoma Cells. Hemasphere 2021; 5:e620. [PMID: 34263144 PMCID: PMC8274796 DOI: 10.1097/hs9.0000000000000620] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 01/16/2021] [Accepted: 06/16/2021] [Indexed: 11/26/2022] Open
Abstract
Mantle cell lymphoma (MCL) accounts for 5%–10% of all lymphomas. The disease’s genetic hallmark is the t(11; 14)(q13; q32) translocation. In younger patients, the first-line treatment is chemoimmunotherapy followed by autologous stem cell transplantation. Upon disease progression, novel and targeted agents such as the BTK inhibitor ibrutinib, the BCL-2 inhibitor venetoclax, or the combination of both are increasingly used, but even after allogeneic stem cell transplantation or CAR T-cell therapy, MCL remains incurable for most patients. Chronic antigenic stimulation of the B-cell receptor (BCR) is thought to be essential for the pathogenesis of many B-cell lymphomas. LRPAP1 has been identified as the autoantigenic BCR target in about 1/3 of all MCLs. Thus, LRPAP1 could be used to target MCL cells, however, there is currently no optimal therapeutic format to integrate LRPAP1. We have therefore integrated LRPAP1 into a concept termed BAR, for B-cell receptor antigens for reverse targeting. A bispecific BAR body was synthesized consisting of the lymphoma-BCR binding epitope of LRPAP1 and a single chain fragment targeting CD3 or CD16 to recruit/engage T or NK cells. In addition, a BAR body consisting of an IgG1 antibody and the lymphoma-BCR binding epitope of LRPAP1 replacing the variable regions was synthesized. Both BAR bodies mediated highly specific cytotoxic effects against MCL cells in a dose-dependent manner at 1–20 µg/mL. In conclusion, LRPAP1 can substitute variable antibody regions in different formats to function in a new therapeutic approach to treat MCL.
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4
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LRPAP1 autoantibodies in mantle cell lymphoma are associated with superior outcome. Blood 2021; 137:3251-3258. [PMID: 33513604 DOI: 10.1182/blood.2020008835] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/23/2020] [Indexed: 11/20/2022] Open
Abstract
Low-density lipoprotein (LDL) receptor-related protein-associated protein 1 (LRPAP1) had been identified by B-cell receptor (BCR) expression cloning and subsequent protein array screening as a frequent and proliferation-inducing autoantigen of mantle cell lymphoma (MCL). Of interest, high-titered and light chain-restricted LRPAP1 autoantibodies were detected in 8 of 28 patients with MCL. In the present study, LRPAP1 autoantibodies in sera of patients treated within the Younger and Elderly trials of the European MCL Network were analyzed regarding frequency, association with disease characteristics, and prognostic impact. LRPAP1 autoantibodies were detected in 41 (13%) of 312 evaluable patients with MCL. These LRPAP1 autoantibodies belonged predominantly to the immunoglobulin G (IgG) class and were clonally light chain restricted (27 with κ light chains, 14 patients with λ light chains). Titers ranged between 1:400 and 1:3200. The presence of LRPAP1 autoantibodies was not significantly associated with any baseline clinical characteristic, however, it was associated with a superior 5-year probability for failure-free survival (FFS) of 70% (95% confidence interval [CI], 57% to 87%) vs 51% (95% CI, 44% to 58%), P = .0052; and for overall survival (OS) of 93% (95% CI, 85% to 100%) vs 68% (95% CI, 62% to 74%), P = .0142. LRPAP1-seropositive patients had a Mantle Cell Lymphoma International Prognostic Index-adjusted hazard ratio for FFS of 0.48 (95% CI 0.27-0.83, P = .0083) and for OS of 0.47 (95% CI 0.24-0.94, P = .032). LRPAP1 autoantibodies were frequently detected in a large cohort of MCL patients treated within prospective multicenter clinical trials. Our results suggest better outcomes for LRPAP1-autoantibody seropositive patients.
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5
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Sumazaki M, Shimada H, Ito M, Shiratori F, Kobayashi E, Yoshida Y, Adachi A, Matsutani T, Iwadate Y, Mine S, Machida T, Kamitsukasa I, Mori M, Sugimoto K, Uzawa A, Kuwabara S, Kobayashi Y, Ohno M, Nishi E, Maezawa Y, Takemoto M, Yokote K, Takizawa H, Kashiwado K, Shin H, Kishimoto T, Matsushita K, Kobayashi S, Nakamura R, Shinmen N, Kuroda H, Zhang XM, Wang H, Goto KI, Hiwasa T. Serum anti-LRPAP1 is a common biomarker for digestive organ cancers and atherosclerotic diseases. Cancer Sci 2020; 111:4453-4464. [PMID: 32939876 PMCID: PMC7734161 DOI: 10.1111/cas.14652] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 08/26/2020] [Accepted: 09/02/2020] [Indexed: 12/26/2022] Open
Abstract
Some cancers are related to atherosclerotic diseases; therefore, these two types of disease may share some antibody biomarkers in common. To investigate this, a first screening of sera was performed from patients with esophageal squamous cell carcinoma (ESCC) or acute ischemic stroke (AIS) for serological identification of antigens using recombinant cDNA expression cloning (SEREX). The amplified luminescent proximity homogeneous assay‐linked immunosorbent assay (AlphaLISA) method, which incorporates glutathione donor beads and anti‐human IgG acceptor beads, was used to evaluate serum antibody levels. SEREX screening identified low‐density lipoprotein receptor–related protein–associated protein 1 (LRPAP1) as a target antigen of serum IgG antibodies in the sera of patients with ESCC or AIS. Antigens, including recombinant glutathione S‐transferase–fused LRPAP1 protein, were prepared to examine serum antibody levels. AlphaLISA revealed significantly higher antibody levels against the LRPAP1 protein in patients with solid cancers such as ESCC and colorectal carcinoma and some atherosclerosis‐related diseases such as AIS and diabetes mellitus compared with healthy donors. Correlation analysis revealed that the elevated serum antibody levels against LRPAP1 were associated with smoking, a well‐known risk factor for both cancer and atherosclerosis. Serum LRPAP1 antibody is therefore a common marker for the early diagnosis of some cancers and atherosclerotic diseases and may reflect diseases caused by habitual smoking.
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Affiliation(s)
- Makoto Sumazaki
- Department of Gastroenterological Surgery and Clinical Oncology, Toho University Graduate School of Medicine, Tokyo, Japan
| | - Hideaki Shimada
- Department of Gastroenterological Surgery and Clinical Oncology, Toho University Graduate School of Medicine, Tokyo, Japan
| | - Masaaki Ito
- Department of Gastroenterological Surgery and Clinical Oncology, Toho University Graduate School of Medicine, Tokyo, Japan
| | - Fumiaki Shiratori
- Department of Gastroenterological Surgery and Clinical Oncology, Toho University Graduate School of Medicine, Tokyo, Japan
| | - Eiichi Kobayashi
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yoichi Yoshida
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Akihiko Adachi
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Tomoo Matsutani
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yasuo Iwadate
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Seiichiro Mine
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.,Department of Neurological Surgery, Chiba Prefectural Sawara Hospital, Chiba, Japan.,Department of Neurological Surgery, Chiba Cerebral and Cardiovascular Center, Chiba, Japan
| | - Toshio Machida
- Department of Neurological Surgery, Chiba Cerebral and Cardiovascular Center, Chiba, Japan.,Department of Neurosurgery, Eastern Chiba Medical Center, Chiba, Japan
| | - Ikuo Kamitsukasa
- Department of Neurology, Chiba Rosai Hospital, Chiba, Japan.,Department of Neurology, Chibaken Saiseikai Narashino Hospital, Chiba, Japan
| | - Masahiro Mori
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Kazuo Sugimoto
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.,Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Akiyuki Uzawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yoshio Kobayashi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Mikiko Ohno
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Department of Pharmacology, Shiga University of Medical Science, Shiga, Japan
| | - Eiichiro Nishi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Department of Pharmacology, Shiga University of Medical Science, Shiga, Japan
| | - Yoshiro Maezawa
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Minoru Takemoto
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba University, Chiba, Japan.,Department of Diabetes, Metabolism and Endocrinology, School of Medicine, International University of Health and Welfare, Chiba, Japan
| | - Koutaro Yokote
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Hirotaka Takizawa
- Port Square Kashiwado Clinic, Kashiwado Memorial Foundation, Chiba, Japan
| | | | - Hideo Shin
- Department of Neurosurgery, Higashi Funabashi Hospital, Chiba, Japan
| | - Takashi Kishimoto
- Department of Molecular Pathology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Kazuyuki Matsushita
- Division of Clinical Genetics and Proteomics, Department of Laboratory Medicine, Chiba University Hospital, Chiba, Japan
| | - Sohei Kobayashi
- Division of Clinical Genetics and Proteomics, Department of Laboratory Medicine, Chiba University Hospital, Chiba, Japan
| | - Rika Nakamura
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan.,Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
| | - Natsuko Shinmen
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan.,Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
| | - Hideyuki Kuroda
- Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
| | - Xiao-Meng Zhang
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Hao Wang
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan.,Department of Anesthesia, The First Affiliated Hospital, Jinan University, Guanzhou, China
| | - Ken-Ichiro Goto
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Takaki Hiwasa
- Department of Gastroenterological Surgery and Clinical Oncology, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.,Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
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6
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Kim SS, Lee SI, Jin HS, Park S. Tuberculosis risk is associated with genetic polymorphisms in the LRP2, CUBN, and VDR genes. Genes Genomics 2020; 42:1189-1196. [PMID: 32803705 DOI: 10.1007/s13258-020-00971-3] [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: 09/05/2019] [Accepted: 07/13/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Vitamin D (Vit. D) is used extensively during tuberculosis treatment. Low levels of serum Vit. D increase the risk of active tuberculosis development. Altered expression of the proteins involved in Vit. D metabolism impairs cathelicidin production, thereby increasing the host susceptibility to tuberculosis. OBJECTIVE We are trying to investigate whether single nucleotide polymorphisms (SNPs) in LRP2, CUBN, and VDR genes could affect tuberculosis development. METHODS We included participants of the Korean Association Resource (KARE), part of the Korean Genome and Epidemiology Study (KoGES), and used their recorded data. A total of 8840 people (4182 men and 4658 women) were eligible subjects. The 5-kb regions from the ends of transcripts of GC, LRP2, CUBN, and VDR genes were amplified to select 13, 47, 70, and 15 SNPs, respectively. For association analysis and statistical analysis, PLINK version 1.07 and PASW Statistics version 18.0 were used. RESULTS Significant correlation was observed in 11, 2, and 1 SNPs in LRP2, CUBN, and VDR genes. The effect of rs6747692 of LRP2 on transcription factor binding was confirmed using RegulomeDB. We confirmed that rs2239182 of VDR is located in the genomic eQTL region and can affect transcription factor binding and gene expression. CONCLUSIONS Genetic polymorphisms in genes encoding proteins involved in Vit. D metabolism influence immune system components. Therefore, such polymorphisms may influence the susceptibility to Mycobacterium tuberculosis invasion and alter the defense mechanisms against Mycobacterium tuberculosis infection. The correlation between genetic variation and tuberculosis development can provide new guidelines for the management of tuberculosis.
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Affiliation(s)
- Sung-Soo Kim
- Department of Biomedical Laboratory Science, College of Life and Health Sciences, Hoseo University, Asan, 31499, Chungnam, Korea
| | - Sang In Lee
- Department of Biomedical Laboratory Science, College of Life and Health Sciences, Hoseo University, Asan, 31499, Chungnam, Korea
| | - Hyun-Seok Jin
- Department of Biomedical Laboratory Science, College of Life and Health Sciences, Hoseo University, Asan, 31499, Chungnam, Korea
| | - Sangjung Park
- Department of Biomedical Laboratory Science, College of Life and Health Sciences, Hoseo University, Asan, 31499, Chungnam, Korea.
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7
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Kukida M, Sawada H, Daugherty A, Lu HS. Megalin: A bridge connecting kidney, the renin-angiotensin system, and atherosclerosis. Pharmacol Res 2020; 151:104537. [PMID: 31707037 PMCID: PMC6980733 DOI: 10.1016/j.phrs.2019.104537] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 11/05/2019] [Indexed: 01/21/2023]
Abstract
Megalin is a member of the low-density lipoprotein receptor superfamily. It has been recognized as an endocytic receptor for a large spectrum of ligands. As a consequence, megalin regulates homeostasis of many molecules and affects multiple physiological and pathophysiological functions. The renin-angiotensin system is a hormonal system. A number of studies have reported contributions of the renin-angiotensin system to atherosclerosis. There is evolving evidence that megalin is a regulator of the renin-angiotensin system, and contributes to atherosclerosis. This brief review provides contemporary insights into effects of megalin on renal functions, the renin-angiotensin system, and atherosclerosis.
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Affiliation(s)
- Masayoshi Kukida
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Hisashi Sawada
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Alan Daugherty
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Hong S Lu
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY, USA.
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8
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Hirano M. An Endocytic Receptor, Megalin-Ligand Interactions: Effects of Glycosylation. TRENDS GLYCOSCI GLYC 2018. [DOI: 10.4052/tigg.1752.1j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Hirano M. An Endocytic Receptor, Megalin-Ligand Interactions: Effects of Glycosylation. TRENDS GLYCOSCI GLYC 2018. [DOI: 10.4052/tigg.1752.1e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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LRPAP1 is a frequent proliferation-inducing antigen of BCRs of mantle cell lymphomas and can be used for specific therapeutic targeting. Leukemia 2018; 33:148-158. [PMID: 29955130 DOI: 10.1038/s41375-018-0182-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 05/17/2018] [Accepted: 05/24/2018] [Indexed: 01/28/2023]
Abstract
The predominant usage of VH4-34 and V3-21 and reports of stereotyped CDR3s suggest a shared antigenic target of B-cell receptors (BCR) from mantle cell lymphomas (MCL). To identify the target antigens of MCL-BCRs, BCRs from 21 patients and seven MCL cell lines were recombinantly expressed and used for antigen screening. The BCRs from 8/21 patients and 2/7 MCL cell lines reacted specifically with the autoantigen low-density lipoprotein receptor-related protein-associated protein 1 (LRPAP1). High-titered and light chain-restricted anti-LRPAP1 serum antibodies were found in MCL patients, but not in controls. LRPAP1 induced proliferation by BCR pathway activation, while an LRPAP1-ETA' toxin-conjugate specifically killed MCL cells with LRPAP1-specific BCRs. Our results suggest a role of LRPAP1 in lymphomagenesis and maintenance of a considerable proportion of MCL cases by chronic autoantigenic stimulation, likely evolving from a chronic autoreactive B-cell response. Importantly, LRPAP1 can be used for a novel therapeutic approach that targets MCL with LRPAP1-reactive BCRs with high specificity.
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11
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Baardman ME, Zwier MV, Wisse LJ, Gittenberger-de Groot AC, Kerstjens-Frederikse WS, Hofstra RMW, Jurdzinski A, Hierck BP, Jongbloed MRM, Berger RMF, Plösch T, DeRuiter MC. Common arterial trunk and ventricular non-compaction in Lrp2 knockout mice indicate a crucial role of LRP2 in cardiac development. Dis Model Mech 2016; 9:413-25. [PMID: 26822476 PMCID: PMC4852499 DOI: 10.1242/dmm.022053] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 01/20/2016] [Indexed: 01/22/2023] Open
Abstract
Lipoprotein-related receptor protein 2 (LRP2) is important for development of the embryonic neural crest and brain in both mice and humans. Although a role in cardiovascular development can be expected, the hearts of Lrp2 knockout (KO) mice have not yet been investigated. We studied the cardiovascular development of Lrp2 KO mice between embryonic day 10.5 (E10.5) and E15.5, applying morphometry and immunohistochemistry, using antibodies against Tfap2α (neural crest cells), Nkx2.5 (second heart field), WT1 (epicardium derived cells), tropomyosin (myocardium) and LRP2. The Lrp2 KO mice display a range of severe cardiovascular abnormalities, including aortic arch anomalies, common arterial trunk (persistent truncus arteriosus) with coronary artery anomalies, ventricular septal defects, overriding of the tricuspid valve and marked thinning of the ventricular myocardium. Both the neural crest cells and second heart field, which are essential for the lengthening and growth of the right ventricular outflow tract, are abnormally positioned in the Lrp2 KO. This explains the absence of the aorto-pulmonary septum, which leads to common arterial trunk and ventricular septal defects. Severe blebbing of the epicardial cells covering the ventricles is seen. Epithelial-mesenchymal transition does occur; however, there are fewer WT1-positive epicardium-derived cells in the ventricular wall as compared to normal, coinciding with the myocardial thinning and deep intertrabecular spaces. LRP2 plays a crucial role in cardiovascular development in mice. This corroborates findings of cardiac anomalies in humans with LRP2 mutations. Future studies should reveal the underlying signaling mechanisms in which LRP2 is involved during cardiogenesis. Summary: This paper sheds a new light on the role of the second heart field and neural crest cells in outflow tract formation in the mouse embryo. Depletion of the LPR2 results in a disturbed contribution pattern and subsequent common arterial trunk.
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Affiliation(s)
- Maria E Baardman
- Department of Genetics, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9713 GZ, The Netherlands
| | - Mathijs V Zwier
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9713 GZ, The Netherlands
| | - Lambertus J Wisse
- Department of Anatomy and Embryology, Leiden University Medical Center, PO-Box 9600, Leiden 2300 RC, The Netherlands
| | | | - Wilhelmina S Kerstjens-Frederikse
- Department of Genetics, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9713 GZ, The Netherlands
| | - Robert M W Hofstra
- Department of Clinical Genetics, Erasmus Medical Center Rotterdam, PO-Box 2040, Rotterdam 3000 CA, The Netherlands Neural Development and Gastroenterology Units, UCL Institute of Child Health, London WC1 NEH, UK
| | - Angelika Jurdzinski
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9713 GZ, The Netherlands
| | - Beerend P Hierck
- Department of Anatomy and Embryology, Leiden University Medical Center, PO-Box 9600, Leiden 2300 RC, The Netherlands
| | - Monique R M Jongbloed
- Department of Cardiology and Department of Anatomy and Embryology, Leiden University Medical Center, PO-Box 9600, Leiden 2300 RC, The Netherlands
| | - Rolf M F Berger
- Center for Congenital Heart Diseases, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9713 GZ, The Netherlands
| | - Torsten Plösch
- Department of Obstetrics and Gynaecology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9713 GZ, The Netherlands
| | - Marco C DeRuiter
- Department of Anatomy and Embryology, Leiden University Medical Center, PO-Box 9600, Leiden 2300 RC, The Netherlands
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12
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Mahadevappa R, Nielsen R, Christensen EI, Birn H. Megalin in acute kidney injury: foe and friend. Am J Physiol Renal Physiol 2013; 306:F147-54. [PMID: 24197071 DOI: 10.1152/ajprenal.00378.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The kidney proximal tubule is a key target in many forms of acute kidney injury (AKI). The multiligand receptor megalin is responsible for the normal proximal tubule uptake of filtered molecules, including nephrotoxins, cytokines, and markers of AKI. By mediating the uptake of nephrotoxins, megalin plays an essential role in the development of some types of AKI. However, megalin also mediates the tubular uptake of molecules implicated in the protection against AKI, and changes in megalin expression have been demonstrated in AKI in animal models. Thus, modulation of megalin expression in response to AKI may be an important part of the tubule cell adaption to cellular protection and regeneration and should be further investigated as a potential target of intervention. This review explores current evidence linking megalin expression and function to the development, diagnosis, and progression of AKI as well as renal protection against AKI.
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Affiliation(s)
- Ravikiran Mahadevappa
- Dept. of Biomedicine, Aarhus Univ., Wilhelm Meyers Allé 3, Bldg. 1234, Aarhus DK-8000, Denmark.
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Abstract
Cobalamin (vitamin B12) deficiency is particularly common in the elderly (>65 years of age), but is often unrecognized because of its subtle clinical manifestations; although they can be potentially serious, particularly from a neuropsychiatric and hematological perspective. In the general population, the main causes of cobalamin deficiency are pernicious anemia and food-cobalamin malabsorption. Food-cobalamin malabsorption syndrome, which has only recently been identified, is a disorder characterized by the inability to release cobalamin from food or its binding proteins. This syndrome is usually caused by atrophic gastritis, related or unrelated to Helicobacter pylori infection, and long-term ingestion of antacids and biguanides. Besides these syndromes, mutations in genes encoding endocytic receptors involved in the ileal absorption and cellular uptake of cobalamin have been recently uncovered and explain, at least in part, the hereditary component of megaloblastic anemia. Management of cobalamin deficiency with cobalamin injections is currently well codified, but new routes of cobalamin administration (oral and nasal) are being studied, especially oral cobalamin therapy for food-cobalamin malabsorption.
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Affiliation(s)
- N Dali-Youcef
- Service de Médecine Interne, Diabète et Maladies Métaboliques, Clinique Médicale B, Hôpital Civil-Hôpitaux Universitaires de Strasbourg, 1 porte de l'Hôpital, 67091 Strasbourg Cedex, France
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14
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Pandey SN, Dixit M, Choudhuri G, Mittal B. Lipoprotein receptor associated protein (LRPAP1) insertion/deletion polymorphism: association with gallbladder cancer susceptibility. ACTA ACUST UNITED AC 2008; 37:124-8. [PMID: 17987404 DOI: 10.1007/s12029-007-9002-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Low-density lipoprotein receptor-related protein associated protein (LRPAP1) insertion/deletion polymorphism influences cholesterol homeostasis and may confer risk for gallstone disease and gallbladder carcinoma (GBC) incidence usually parallels with the prevalence of cholelithiosis. AIM We aimed to examine the role of LRPAP1 polymorphism in susceptibility to GBC. METHODS Present case control study included 129 proven GBC patients, 183 gallstone patients, and 208 healthy controls. Genotyping was done by polymerase chain reaction-restriction fragment length polymorphism method. RESULTS The D allele of LRPAP1 was significantly higher in GBC patients as compared to gallstone patients (p = 0.013; OR = 1.6, 95% CI = 1.1-2.4). However, II genotype and I allele was associated with reduced risk of GBC as compared to gallstone patients (p = 0.002; OR = 0.1, 95% CI = 0.1-0.6; p = 0.013; OR = 0.6, 95% CI = 0.4-0.8) The increased risk due to D allele was limited to female GBC patients (p = 0.021; OR = 1.8, 95% CI = 1.1-3.0). However, reduced risk due to II genotype and I allele was observed which was also confined to female GBC patients (p = 0.005; OR = 0.1, 95% CI = 0.1-0.6; p = 0.021; OR = 0.5, 95% CI = 0.3-0.8). On comparing GBC patients having gallstone with gallstone patients, high risk was observed in the GBC patients having gallstone due to the presence of D allele (p = 0.032; OR = 1.7, 95% CI = 1.0-2.8). However, low risk was observed because of I allele in GBC patients with gallstone in comparison to gallstone patients (p = 0.032, OR = 0.6, 95% CI = 0.4-0.9). CONCLUSION It appears that 'D' allele may modulate the susceptibility of GBC, and the risk is independent to genetic risk of gallstone.
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Affiliation(s)
- Sachchida Nand Pandey
- Department of Genetics, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
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15
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Dixit M, Choudhuri G, Keshri LJ, Mittal B. Association of low density lipoprotein receptor related protein-associated protein (LRPAP1) gene insertion/deletion polymorphism with gallstone disease. J Gastroenterol Hepatol 2006; 21:847-9. [PMID: 16704534 DOI: 10.1111/j.1440-1746.2005.03931.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND AND AIM Gallstones are byproducts of cholesterol supersaturated bile. Various studies have indicated that there might be a genetic predisposition to the disease. Receptor-associated protein (RAP) is a molecular chaperone for low density lipoprotein receptor-related protein (LRP), which plays a key role in cholesterol metabolism. Intron 5 insertion/deletion polymorphism of RAP gene (LRPAP1) has been implicated in other diseases sharing etiology with gallstone disease (GSD). METHODS To analyze the association of insertion/deletion polymorphism in GSD, 130 gallstone patients and 202 healthy subjects took part in the present study. For genotyping, polymerase chain reaction was followed by 2% agarose gel electrophoresis. RESULTS The results showed that frequencies of D and I allele were 65.77% and 34.23% in patients, 76.24% and 23.76% in controls, respectively. Frequency of I allele was significantly higher in the patient group than in the control group (P = 0.003). CONCLUSION In the present study I (insertion) allele was found to be associated with GSD.
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16
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Dietze I, Fritz B, Huhle D, Simoens W, Piecha E, Rehder H. Clinical, Cytogenetic and Molecular Investigation in a Fetus with Wolf-Hirschhorn Syndrome with Paternally Derived 4p Deletion. Fetal Diagn Ther 2004; 19:251-60. [PMID: 15067236 DOI: 10.1159/000076707] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2002] [Accepted: 04/24/2003] [Indexed: 11/19/2022]
Abstract
Wolf-Hirschhorn (4p-) syndrome (WHS), caused by partial deletion of the short arm of chromosome 4, has been extensively described in children and young adults. Knowledge on fetuses with WHS is still limited due to the small number of published cases. We report on a fetus with prenatally diagnosed severe intrauterine growth retardation, reduced thoracal diameter, clubfeet deformity and midface hypoplasia including slight microretrognathia indicative for fetal karyotyping. Chromosome analysis after amniocentesis revealed a de novo terminal deletion of chromosome 4p [karyotype: 46,XX,del(4) (p16)] which was confirmed by FISH. Analyses of a set of polymorphic markers mapping in 4pter->4p15.3 showed absence of paternal haplotypes. These observations corroborate the preferential paternal origin of the de novo 4p deletion in WHS patients. Furthermore, the distal breakpoint could be narrowed to band 4p16.1. At autopsy, the fetus showed typical craniofacial dysmorphic signs of WHS, severe IUGR and delayed bone age. This report suggests the possibility of recognising the particular phenotype of WHS in utero by prenatal ultrasound and emphasises the importance of karyotyping fetuses with severe IUGR, especially when the amount of amniotic fluid is normal.
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Affiliation(s)
- Ilona Dietze
- Institute of Clinical Genetics, Philipps University, Marburg, Germany
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17
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Christensen EI, Birn H. Megalin and cubilin: multifunctional endocytic receptors. Nat Rev Mol Cell Biol 2002; 3:256-66. [PMID: 11994745 DOI: 10.1038/nrm778] [Citation(s) in RCA: 578] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The ability to take up substances from the surrounding environment not only provides cells with vital nutrients, but also enables the selective transport of substances from one compartment to another. Megalin and cubilin are two structurally different endocytic receptors that interact to serve such functions. Evidence has accumulated in recent years to indicate that these receptors have important functions in both normal physiology and pathology.
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Affiliation(s)
- Erik Ilsø Christensen
- Department of Cell Biology, University of Aarhus, University Park, Building 234, DK-8000 Aarhus C, ;
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18
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Wojnar P, Lechner M, Merschak P, Redl B. Molecular cloning of a novel lipocalin-1 interacting human cell membrane receptor using phage display. J Biol Chem 2001; 276:20206-12. [PMID: 11287427 DOI: 10.1074/jbc.m101762200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Human lipocalin-1 (Lcn-1, also called tear lipocalin), a member of the lipocalin structural superfamily, is produced by a number of glands and tissues and is known to bind an unusually large array of hydrophobic ligands. Apart from its specific function in stabilizing the lipid film of human tear fluid, it is suggested to act as a physiological scavenger of potentially harmful lipophilic compounds, in general. To characterize proteins involved in the reception, detoxification, or degradation of these ligands, a cDNA phage-display library from human pituitary gland was constructed and screened for proteins interacting with Lcn-1. Using this method an Lcn-1 interacting phage was isolated that expressed a novel human protein. Molecular cloning and analysis of the entire cDNA indicated that it encodes a 55-kDa protein, lipocalin-1 interacting membrane receptor (LIMR), with nine putative transmembrane domains. The cell membrane location of this protein was confirmed by immunocytochemistry and Western blot analysis of membrane fractions of human NT2 cells. Independent biochemical investigations using a recombinant N-terminal fragment of LIMR also demonstrated a specific interaction with Lcn-1 in vitro. Based on these data, we suggest LIMR to be a receptor of Lcn-1 ligands. These findings constitute the first report of cloning of a lipocalin interacting, plasma membrane-located receptor, in general. In addition, a sequence comparison supports the biological relevance of this novel membrane protein, because genes with significant nucleotide sequence similarity are present in Takifugu rubripes, Drosophila melanogaster, Caenorhabditis elegans, Mus musculus, Bos taurus, and Sus scrofa. According to data derived from the human genome sequencing project, the LIMR-encoding gene has to be mapped on human chromosome 12, and its intron/exon organization could be established. The entire LIMR-encoding gene consists of about 13.7 kilobases in length and contains 16 introns with a length between 91 and 3438 base pairs.
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Affiliation(s)
- P Wojnar
- Department of Microbiology (Medical School), University of Innsbruck, Fritz Pregl Strasse 3, A-6020 Innsbruck, Austria
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19
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Christensen EI, Birn H. Megalin and cubilin: synergistic endocytic receptors in renal proximal tubule. Am J Physiol Renal Physiol 2001; 280:F562-73. [PMID: 11249847 DOI: 10.1152/ajprenal.2001.280.4.f562] [Citation(s) in RCA: 243] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The multiligand, endocytic receptors megalin and cubilin are colocalized in the renal proximal tubule. They are heavily expressed in the apical endocytic apparatus. Megalin is a 600-kDa transmembrane protein belonging to the low-density lipoprotein-receptor family. The cytoplasmic tail contains three NPXY motifs that mediate the clustering in coated pits and are possibly involved in signaling functions. Cubilin, also known as the intestinal intrinsic factor-cobalamin receptor, is a 460-kDa receptor with no transmembrane domain and no known signal for endocytosis. Because the two receptors bind each other with high affinity and colocalize in several tissues, it is highly conceivable that megalin mediates internalization of cubilin and its ligands. Both receptors are important for normal tubular reabsorption of proteins, including albumin. Among the proteins normally filtered in the glomeruli, cubilin has been shown to bind albumin, immunoglobulin light chains, and apolipoprotein A-I. The variety of filtered ligands identified for megalin include vitamin-binding proteins, hormones, enzymes, apolipoprotein H, albumin, and beta(2)- and alpha(1)-microglobulin. Loss of these proteins and vitamins in the urine of megalin-deficient mice illustrates the physiological importance of this receptor.
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Affiliation(s)
- E I Christensen
- Department of Cell Biology, Institute of Anatomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
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20
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Figueroa DJ, Hess JF, Ky B, Brown SD, Sandig V, Hermanowski-Vosatka A, Twells RC, Todd JA, Austin CP. Expression of the type I diabetes-associated gene LRP5 in macrophages, vitamin A system cells, and the Islets of Langerhans suggests multiple potential roles in diabetes. J Histochem Cytochem 2000; 48:1357-68. [PMID: 10990489 DOI: 10.1177/002215540004801006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
LRP5 is a novel member of the low-density lipoprotein receptor family that is genetically associated with Type 1 diabetes. As a start to defining the normal function of LRP5 and to generate testable hypotheses of its potential role in Type 1 diabetes pathogenesis, we carried out an extensive expression analysis of this gene at the mRNA and protein levels in normal human, monkey, and mouse, as well as in non-obese diabetic (NOD) mice at several stages of diabetes development. In all species, expression of LRP5 was found in four functionally important cell types: the distributed mononuclear phagocyte system, the islets of Langerhans, vitamin A-metabolizing cells, and CNS neurons. Given the critical role of macrophages in the onset and progression of islet cell destruction in Type 1 diabetes and the hypothesized role of retinoids as modifiers of diabetes progression, these findings suggest that LRP5 may confer Type 1 diabetes risk by altering the normal functioning of one or more of these regulatory systems. Specifically, given that the LRP5 polymorphisms associated with diabetes are in the promoter region of the gene, alterations in LRP5 expression may be responsible for diabetes susceptibility and therefore may be potential targets for therapeutic intervention. (J Histochem Cytochem 48:1357-1368, 2000)
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Affiliation(s)
- D J Figueroa
- Department of Pharmacology, Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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21
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Kazen-Gillespie KA, Ragsdale DS, D'Andrea MR, Mattei LN, Rogers KE, Isom LL. Cloning, localization, and functional expression of sodium channel beta1A subunits. J Biol Chem 2000; 275:1079-88. [PMID: 10625649 DOI: 10.1074/jbc.275.2.1079] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Auxiliary beta1 subunits of voltage-gated sodium channels have been shown to be cell adhesion molecules of the Ig superfamily. Co-expression of alpha and beta1 subunits modulates channel gating as well as plasma membrane expression levels. We have cloned, sequenced, and expressed a splice variant of beta1, termed beta1A, that results from an apparent intron retention event. beta1 and beta1A are structurally homologous proteins with type I membrane topology; however, they contain little to no amino acid homology beyond the shared Ig loop region. beta1A mRNA expression is developmentally regulated in rat brain such that it is complementary to beta1. beta1A mRNA is expressed during embryonic development, and then its expression becomes undetectable after birth, concomitant with the onset of beta1 expression. In contrast, beta1A mRNA is expressed in adult adrenal gland and heart. Western blot analysis revealed beta1A protein expression in heart, skeletal muscle, and adrenal gland but not in adult brain or spinal cord. Immunocytochemical analysis of beta1A expression revealed selective expression in brain and spinal cord neurons, with high expression in heart and all dorsal root ganglia neurons. Co-expression of alphaIIA and beta1A subunits in Chinese hamster lung 1610 cells results in a 2.5-fold increase in sodium current density compared with cells expressing alphaIIA alone. This increase in current density reflected two effects of beta1A: 1) an increase in the proportion of cells expressing detectable sodium currents and 2) an increase in the level of functional sodium channels in expressing cells. [(3)H]Saxitoxin binding analysis revealed a 4-fold increase in B(max) with no change in K(D) in cells coexpressing alphaIIA and beta1A compared with cells expressing alphaIIA alone. beta1A-expressing cell lines also revealed subtle differences in sodium channel activation and inactivation. These effects of beta1A subunits on sodium channel function may be physiologically important events in the development of excitable cells.
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Affiliation(s)
- K A Kazen-Gillespie
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109-0632, USA
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22
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Oleinikov AV, Feliz BJ, Makker SP. A small N-terminal 60-kD fragment of gp600 (megalin), the major autoantigen of active Heymann nephritis, can induce a full-blown disease. J Am Soc Nephrol 2000; 11:57-64. [PMID: 10616840 DOI: 10.1681/asn.v11157] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Active Heymann nephritis of rat, an autoimmune glomerular disease, is an immunohistological, ultrastructural, and clinical model of human membranous glomerulonephritis. Both diseases in their full-blown form are characterized by (1) the formation of large, subepithelial glomerular immune deposits, which stain for IgG, C3, and membrane attack (C5b-9) components of complement and (2) the excretion of large amounts of protein in the urine (proteinuria). The target autoantigen of active Heymann nephritis is a large transmembrane renal glycoprotein with a molecular weight of approximately 600 kD, variously named gp600, gp330, LRP-2, or "megalin." This study was performed to identify the region in this enormously large glycoprotein that would produce full-blown active Heymann nephritis. A stable, small (60-kD) proteolytic fragment of gp600 was isolated and localized to the N-terminal end of the molecule using Western blot, sequencing, and amino acid analyses. Based on its primary structure, this fragment contains approximately 60 cysteine residues, the cross-linking of which to each other probably explains its stability. Immunization of rats with this fragment induced a full-blown disease that was comparable to the disease induced by a preparation containing the whole protein. These results indicate that this small fragment, retaining the natural disulfide bonds and probably its overall structure, contains those B and T cell epitopes that are sufficient to produce this organ-specific autoimmune disease.
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Affiliation(s)
- Andrew V Oleinikov
- Department of Pediatrics, Division of Nephrology, School of Medicine, University of California, Davis, California
| | - Brady J Feliz
- Department of Pediatrics, Division of Nephrology, School of Medicine, University of California, Davis, California
| | - Sudesh P Makker
- Department of Pediatrics, Division of Nephrology, School of Medicine, University of California, Davis, California
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23
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Christensen EI, Willnow TE. Essential role of megalin in renal proximal tubule for vitamin homeostasis. J Am Soc Nephrol 1999; 10:2224-36. [PMID: 10505701 DOI: 10.1681/asn.v10102224] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- E I Christensen
- Department of Cell Biology, Institute of Anatomy, University of Aarhus, Denmark.
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24
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Nilsson L, Gåfvels M, Musakka L, Ensler K, Strickland DK, Angelin B, Hamsten A, Eriksson P. VLDL activation of plasminogen activator inhibitor-1 (PAI-1) expression: involvement of the VLDL receptor. J Lipid Res 1999. [DOI: 10.1016/s0022-2275(20)32126-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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25
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Van Leuven F, Thiry E, Stas L, Nelissen B. Analysis of the human LRPAP1 gene coding for the lipoprotein receptor-associated protein: identification of 22 polymorphisms and one mutation. Genomics 1998; 52:145-51. [PMID: 9782079 DOI: 10.1006/geno.1998.5413] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The lipoprotein receptor-associated protein (RAP) is considered a chaperone protein for the lipoprotein receptor-related protein (LRP) and for the other members of the LDL receptor family. Genetic analysis is anticipated to help in delineating groups or individuals with potential defects or problems in this regard. A combined amplification/sequencing strategy was developed to analyze the human LRPAP1 gene for polymorphisms and mutations. The LRPAP1 gene was amplified from genomic DNA in four long-range PCR amplicons, 2.4 to 7.6 kb in size. Three amplicons were finally used as templates with 14 sequencing primers to obtain the sequence of the eight exons and large portions of adjacent introns from individual DNA. This strategy, applied to sequence the LRPAP1 gene of 14 unrelated, normal individuals revealed, in total, 23 distinct mutations and polymorphisms, mostly intronic substitutions and deletions. In this small group 1 expressed mutation was encountered on one allele in 2 unrelated individuals: a G to A transition results in the replacement of valine by methionine in exon 7 at position 311 of the human RAP precursor protein.
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Affiliation(s)
- F Van Leuven
- Center for Human Genetics, Flemish Institute for Biotechnology, K. U. Leuven, Campus Gasthuisberg, Leuven, B-3000, Belgium.
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26
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Yamazaki H, Bujo H, Saito Y. A novel member of the LDL receptor gene family with eleven binding repeats is structurally related to neural adhesion molecules and a yeast vacuolar protein sorting receptor. J Atheroscler Thromb 1998; 4:20-6. [PMID: 9583350 DOI: 10.5551/jat1994.4.20] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We now have discovered and characterized a novel multi-domain protein and classified it as a member of the LDL receptor gene family. The approximately 250 kDa membrane protein, termed LR11, highly conserved in man, rabbit and chicken, contains a cluster of 11 LDL receptor ligand binding repeats, a group of 5 LDL receptor "YWTD" repeats, a large hexarepeat domain of structural elements found in neural cell adhesion molecules, and a domain with similarity to a yeast receptor for vacuolar protein sorting, VPS10. The cytoplasmic domain exhibits features typical of endocytosis-competent coated pit receptors. The mosaic, and presumably multifunctional, receptor is expressed abundantly in brain, liver and adrenal glands. Ligand blotting of LR11-transfected cells demonstrated that LR11 binds apolipoproteinE-containing lipoproteins, as well as other members of LDL receptor gene family. In contrast to the LDL receptor, the mRNA levels in rabbit liver is unaffected by hyperlipidemia. The features of this highly conserved and complex mosaic protein suggest the importance of the ever expanding LDL receptor gene family in the evolution and proposed multifunctionality.
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Affiliation(s)
- H Yamazaki
- Second Department of Internal Medicine, Chiba University School of Medicine, Japan
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27
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Hiltunen TP, Luoma JS, Nikkari T, Ylä-Herttuala S. Expression of LDL receptor, VLDL receptor, LDL receptor-related protein, and scavenger receptor in rabbit atherosclerotic lesions: marked induction of scavenger receptor and VLDL receptor expression during lesion development. Circulation 1998; 97:1079-86. [PMID: 9531255 DOI: 10.1161/01.cir.97.11.1079] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Atherosclerotic lesions contain foam cells that arise from monocyte-macrophages and smooth muscle cells (SMCs) by excessive uptake of lipoproteins. There are many candidate receptors for the lipid accumulation, such as LDL receptor (LDLR), VLDL receptor (VLDLR), LDL receptor-related protein (LRP), and scavenger receptors (SRs). However, little quantitative information exists on the expression of these receptors in normal and atherosclerotic arteries. METHODS AND RESULTS Competitive reverse transcription-polymerase chain reaction and in situ hybridization were used for the studies in New Zealand White (NZW) and Watanabe heritable hyperlipidemic (WHHL) rabbit aortic intima-medias. NZW rabbits were fed a 1% cholesterol diet for 0 (control group), 3, 6, or 14 weeks. LDLR mRNA expression was low in aortic intima-medias of all groups. Of the analyzed receptors, LRP had the highest expression in the control group, and its mRNA was induced threefold in the 14-week group, the aortas of which had extensive lesions. SR expression was low and VLDLR expression moderate in the control group. Both receptors were highly induced during cholesterol feeding (SRs, 3-fold and 270-fold induction; VLDLR, 15-fold and 100-fold induction in the 3-week and 14-week groups, respectively). Comparable results were obtained from WHHL rabbits: high basal LRP mRNA in normal intima-medias; moderate induction of LRP and marked induction of SRs and VLDLR in fatty streaks and fatty plaques. In situ hybridization indicated that LRP and VLDLR were expressed in SMCs and macrophages. VLDLR expression was also observed in endothelial cells. SR expression was detected only in macrophages. CONCLUSIONS SR and VLDLR mRNAs were highly induced in atherosclerotic lesions. VLDLR and LRP may be involved in the formation of both SMC-and macrophage-derived foam cells, whereas SRs play an important role in lipid uptake in macrophages.
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Affiliation(s)
- T P Hiltunen
- Department of Medical Biochemistry, University of Tampere Medical School, Tampere University Hospital, Finland
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28
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Stefansson S, Chappell DA, Argraves KM, Strickland DK, Argraves WS. Glycoprotein 330/low density lipoprotein receptor-related protein-2 mediates endocytosis of low density lipoproteins via interaction with apolipoprotein B100. J Biol Chem 1995; 270:19417-21. [PMID: 7642623 DOI: 10.1074/jbc.270.33.19417] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The ability of glycoprotein 330/low density lipoprotein receptor-related protein-2 (LRP-2) to function as a lipoprotein receptor was investigated using cultured mouse F9 teratocarcinoma cells. Treatment with retinoic acid and dibutyryl cyclic AMP, which induces F9 cells to differentiate into endoderm-like cells, produced a 50-fold increase in the expression of LRP-2. Levels of the other members of the low density lipoprotein (LDL) receptor (LDLR) family, including LDLR, the very low density lipoprotein receptor, and LRP-1, were reduced. When LDL catabolism was examined in these cells, it was found that the treated cells endocytosed and degraded at 10-fold higher levels than untreated cells. The increased LDL uptake coincided with increased LRP-2 activity of the treated cells, as measured by uptake of both 125I-labeled monoclonal LRP-2 antibody and the LRP-2 ligand prourokinase. The ability of LDL to bind to LRP-2 was demonstrated by solid-phase binding assays. This binding was inhibitable by LRP-2 antibodies, receptor-associated protein (the antagonist of ligand binding for all members of the LDLR family), or antibodies to apoB100, the major apolipoprotein component of LDL. In cell assays, LRP-2 antibodies blocked the elevated 125I-LDL internalization and degradation observed in the retinoic acid/dibutyryl cyclic AMP-treated F9 cells. A low level of LDL endocytosis existed that was likely mediated by LDLR since it could not be inhibited by LRP-2 antibodies, but was inhibited by excess LDL, receptor-associated protein, or apoB100 antibody. The results indicate that LRP-2 can function to mediate cellular endocytosis of LDL, leading to its degradation. LRP-2 represents the second member of the LDLR family identified as functioning in the catabolism of LDL.
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Affiliation(s)
- S Stefansson
- Biochemistry Department, J.H. Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA
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29
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Kounnas MZ, Loukinova EB, Stefansson S, Harmony JA, Brewer BH, Strickland DK, Argraves WS. Identification of glycoprotein 330 as an endocytic receptor for apolipoprotein J/clusterin. J Biol Chem 1995; 270:13070-5. [PMID: 7768901 DOI: 10.1074/jbc.270.22.13070] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Glycoprotein 330 (gp330) is a member of a family of endocytic receptors related to the low density lipoprotein receptor. gp330 has previously been shown to bind a number of ligands in common with its family member, the low density lipoprotein receptor-related protein (LRP). To identify ligands specific for gp330 and relevant to its localization on epithelia such as in the mammary gland, gp330-Sepharose affinity chromatography was performed. As a result, a 70-kDa protein was selected from human milk and identified by protein sequencing to be apolipoprotein J/clusterin (apoJ). Solid-phase binding assays confirmed that gp330 bound to apoJ with high affinity (Kd = 14.2 nM). Similarly, gp330 bound to apoJ transferred to nitrocellulose after SDS-polyacrylamide gel electrophoresis. LRP, however, showed no binding to apoJ in either type of assay. The binding of gp330 to apoJ could be competitively inhibited with excess apoJ as well as with the gp330 ligands apolipoprotein E, lipoprotein lipase, and the receptor-associated protein, a 39-kDa protein that acts to antagonize binding of all known ligands for gp330 and LRP. Several cultured cell lines that express gp330 and ones that do not express the receptor were examined for their ability to bind and internalize 125I-apoJ. Only cells that expressed gp330 endocytosed and degraded radiolabeled apoJ. Furthermore, F9 cells treated with retinoic acid and dibutyryl cyclic AMP to increase expression levels of gp330 displayed an increased capacity to internalize and degrade apoJ. Cellular internalization and degradation of radiolabeled apoJ could be inhibited with unlabeled apoJ, receptor-associated protein, and gp330 antibodies. The results indicate that gp330 but not LRP can bind to apoJ in vitro and that gp330 expressed by cells can mediate apoJ endocytosis leading to lysosomal degradation.
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Affiliation(s)
- M Z Kounnas
- J. H. Holland Laboratory, Biochemistry Department American Red Cross, Rockville, Maryland 20855, USA
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Stefansson S, Kounnas MZ, Henkin J, Mallampalli RK, Chappell DA, Strickland DK, Argraves WS. gp330 on type II pneumocytes mediates endocytosis leading to degradation of pro-urokinase, plasminogen activator inhibitor-1 and urokinase-plasminogen activator inhibitor-1 complex. J Cell Sci 1995; 108 ( Pt 6):2361-8. [PMID: 7673355 DOI: 10.1242/jcs.108.6.2361] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Glycoprotein 330 (gp330) is a member of a family of receptors related to the low density lipoprotein receptor (LDLR). Although several ligands have been shown to bind gp330 in solid-phase assays, the ability of gp330 to mediate ligand endocytosis has not been demonstrated. To develop a cellular model for gp330 function we screened a variety of cultured cell lines and identified several that expressed this protein, including immortalized rat type II pneumocytes and a human and two rodent tumor cell lines. Using type II pneumocytes, endocytosis of a previously described gp330 ligand, urokinase (uPA) complexed with plasminogen activator inhibitor-1 (uPA:PAI-1) and two new ligands, PAI-1 and pro-uPA, was demonstrated. RAP, the 39 kDa receptor-associated protein known to antagonize ligand binding to gp330 in solid-phase binding assays, completely inhibited both internalization and degradation of the radiolabeled ligands by type II pneumocytes. This suggested that the clearance of these ligands was dependent on either gp330 or the LDLR-related protein (LRP), which shares several ligand-binding characteristics with gp330. By using polyclonal antibodies to gp330, the cellular internalization and degradation of the ligands were inhibited by 30–50%; remaining ligand internalization and degradation activity could be partially inhibited by polyclonal antibodies against LRP. These findings indicate that gp330, like other LDLR family members, mediates endocytosis of its ligands. In addition, gp330 acts in concert with LRP in type II pneumocytes to mediate clearance of a variety of proteins involved in plasminogen activation, including uPA:PAI-1 complexes PAI-1 and pro-uPA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Stefansson
- Biochemistry Department, J. H. Holland Laboratory, American Red Cross, Rockville, MD 20855, USA
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Mikhailenko I, Kounnas MZ, Strickland DK. Low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor mediates the cellular internalization and degradation of thrombospondin. A process facilitated by cell-surface proteoglycans. J Biol Chem 1995; 270:9543-9. [PMID: 7721883 DOI: 10.1074/jbc.270.16.9543] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Thrombospondin (TSP) is a cell and matrix glycoprotein that interacts with a variety of molecules. Newly synthesized thrombospondin is either incorporated into the extracellular matrix, or binds to the cell surface where it is rapidly internalized and degraded (McKeown-Longo, P. J., Hanning, R., and Mosher, D. F. (1984) J. Cell Biol. 98, 22-28). In the current investigation we identify the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) as a receptor responsible for mediating the internalization of TSP leading to its degradation. LRP is a large cell surface receptor consisting of a 515-kDa heavy chain and an 85-kDa light chain proteolytically derived from a 600-kDa precursor. A specific and high affinity interaction between purified LRP and TSP was demonstrated by homologous ligand competition experiments, where a KD of 3-20 nM was measured using different preparations of TSP. The binding of TSP to purified LRP was completely inhibited by the 39-kDa receptor-associated protein, a known antagonist of ligand binding by LRP. Cultured fibroblasts rapidly internalize and degrade 125I-labeled TSP via a receptor-mediated process. This process is inhibited by receptor-associated protein and by antibodies against LRP, indicating that LRP is mediating the cellular internalization of TSP. Our studies also confirm that the efficient catabolism of TSP requires the participation of cell surface proteoglycans, since digestion of cells with heparitinase markedly reduces the extent of LRP-mediated TSP degradation. The ability of LRP to directly bind and mediate the cellular internalization and degradation of TSP indicates that this receptor may play an important role in the catabolism of TSP in vivo.
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Affiliation(s)
- I Mikhailenko
- Holland Laboratory, Department of Biochemistry, American Red Cross, Rockville, Maryland 20855, USA
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Van Leuven F, Hilliker C, Serneels L, Umans L, Overbergh L, De Strooper B, Fryns JP, Van den Berghe H. Cloning, characterization, and chromosomal localization to 4p16 of the human gene (LRPAP1) coding for the alpha 2-macroglobulin receptor-associated protein and structural comparison with the murine gene coding for the 44-kDa heparin-binding protein. Genomics 1995; 25:492-500. [PMID: 7789983 DOI: 10.1016/0888-7543(95)80050-v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We report the molecular cloning of the human gene (symbol LRPAP1) coding for the alpha 2-macroglobulin receptor-associated protein (A2MRAP), as well as the gene coding for the 44-kDa heparin-binding protein (HBP-44), its murine counterpart. For both, genomic cosmid clones were isolated, and for the human gene a bacteriophage P1 clone containing the entire A2MRAP gene was also retrieved. The genes were characterized after subcloning: in both species, the known coding part of the cDNA is encoded by eight exons, and the position of the boundaries of the exons was conserved. The human LRPAP1 locus was assigned to chromosome 4 by PCR of human-hamster hybrid cell lines and by fluorescence in situ hybridization to band 4p16.3. This maps closely to the variable constitutional deletions of the short arm of chromosome 4, observed cytogenetically in patients with the Wolf-Hirschhorn syndrome. Metaphase spreads of two such patients were analyzed by fluorescence in situ hybridization with an LRPAP1 genomic probe. The first patient, with karyotype 46,XY,del4(p14-p16.1), had retained both copies of the LRPAP1 gene. In contrast, the other patient, with karyotype 46,XY,del4(p15.3-pter), displayed no signal for LRPAP1 on the deleted chromosome.
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Affiliation(s)
- F Van Leuven
- Center for Human Genetics, University of Leuven, Belgium
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Battey F, Gåfvels M, FitzGerald D, Argraves W, Chappell D, Strauss J, Strickland D. The 39-kDa receptor-associated protein regulates ligand binding by the very low density lipoprotein receptor. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31648-4] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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