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Yamamura-Miyazaki N, Sakakibara N, Nozu K, Shima Y, Satomura K, Yamamoto S, Baba M, Fujiwara K, Yamamoto K, Michigami T. Identification of CUBN variants in triplets with a 20-year history of proteinuria. CEN Case Rep 2024:10.1007/s13730-024-00919-6. [PMID: 39102129 DOI: 10.1007/s13730-024-00919-6] [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: 05/11/2024] [Accepted: 07/20/2024] [Indexed: 08/06/2024] Open
Abstract
CUBN encodes cubilin, which plays a role in the reabsorption of glomerular-filtered albumin in the proximal tubule. CUBN-related proteinuria was recently established as a new disease concept and may be present in proteinuric cases that were previously undiagnosed either genetically or histologically. We herein report a case of triplets diagnosed with chronic benign proteinuria due to CUBN variants 20 years after its onset. The proband, the first child of triplets, tested positive for urinary protein several times during the neonatal period. A urine screening test at 3 years old was positive. Proteinuria persisted for years within a non-nephrotic range. Kidney biopsy at 8 years old revealed minor glomerular abnormalities. Renin-angiotensin system inhibitors were started for albumin-based proteinuria but were ineffective. Since the two other triplets had similar courses, analyses of the NPHS1/2 and WT1 genes were performed but revealed no abnormalities. The triplets transitioned to adult care at 15 years old. CUBN-related proteinuria was reported in 2020; therefore, we re-analyzed their DNA samples and identified compound heterozygous variants in CUBN in all three triplets. The molecular diagnosis of CUBN-related proteinuria will save patients from unnecessary treatments and concerns about renal prognosis.
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Affiliation(s)
- Natsumi Yamamura-Miyazaki
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, 840 Murodo-Cho, Izumi, Osaka, 594-1101, Japan.
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Hyogo, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Hyogo, Japan
| | - Yuko Shima
- Department of Pediatrics, Wakayama Medical University, Wakayama, Japan
| | - Kenichi Satomura
- Department of Internal Medicine, Meisei Daini Hospital, Osaka, Japan
| | | | - Minato Baba
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, 840 Murodo-Cho, Izumi, Osaka, 594-1101, Japan
| | - Kaori Fujiwara
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, 840 Murodo-Cho, Izumi, Osaka, 594-1101, Japan
| | - Katsusuke Yamamoto
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, 840 Murodo-Cho, Izumi, Osaka, 594-1101, Japan
| | - Toshimi Michigami
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, 840 Murodo-Cho, Izumi, Osaka, 594-1101, Japan
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka, Japan
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Žužul S, Kelam N, Racetin A, Kovačević P, Konjevoda S, Filipović N, Pavlović N, Vukojević K. Immunoexpression Patterns of Megalin, Cubilin, Caveolin-1, Gipc1 and Dab2IP in the Embryonic and Postnatal Development of the Kidneys in Yotari ( Dab1-/-) Mice. Biomedicines 2024; 12:1542. [PMID: 39062115 PMCID: PMC11274389 DOI: 10.3390/biomedicines12071542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2024] [Revised: 07/04/2024] [Accepted: 07/08/2024] [Indexed: 07/28/2024] Open
Abstract
Our study examines the immunoexpression patterns of Megalin, Cubilin, Caveolin-1, Gipc1 and Dab2IP in the embryonic development (E) and postnatal (P) mouse kidney, with a focus on differentiating patterns between wild-type (wt) and yotari, Dab1-/- (yot) mice. Immunofluorescence revealed raised immunoexpression of receptors Megalin and Cubilin at the ampulla/collecting ducts and convoluted tubules across all developmental stages, with the most prominent immunoexpression observed in the convoluted tubules and the parietal epithelium of the Bowman's capsule. Quantitative analysis showed a higher percentage of Megalin and Cubilin in wt compared to yot mice at E13.5. Co-expression of Megalin and Cubilin was observed at the apical membrane of convoluted tubules and the parietal layer of the Bowman's capsule. The staining intensity of Megalin varied across developmental stages, with the strongest reactivity observed at the ampulla and collecting ducts at embryonic day (E) 13.5 in wt mice. In contrast, Caveolin-1 exhibited high immunoexpression in the metanephric mesenchyme, blood vessels, and the border area between the metanephric mesenchyme and renal vesicle, with a decrease in immunoexpression as development progressed. Gipc1 showed diffuse cytoplasmic staining in metanephric mesenchyme, convoluted tubules and collecting ducts, with significant differences in immunoexpression between wild-type and yot mice at both investigated embryonic time points. Dab2IP immunofluorescent staining was most prominent in renal vesicle/glomeruli and ampulla/collecting ducts at E13.5, with mild staining intensity observed in the distal convoluted tubules postnatally. Our findings elucidate distinct immunoexpression of patterns and potential parts of these proteins in the development and function of the kidney, highlighting the importance of further investigation into their regulatory mechanisms.
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Affiliation(s)
- Sani Žužul
- Clinic for Surgery, Clinical Hospital Firule, 21 000 Split, Croatia;
| | - Nela Kelam
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, 21 000 Split, Croatia; (N.K.); (A.R.); (N.F.); (N.P.)
- Center for Translational Research in Biomedicine, School of Medicine, University of Split, 21 000 Split, Croatia
| | - Anita Racetin
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, 21 000 Split, Croatia; (N.K.); (A.R.); (N.F.); (N.P.)
- Center for Translational Research in Biomedicine, School of Medicine, University of Split, 21 000 Split, Croatia
| | - Petra Kovačević
- Department of Ophthalmology, University Hospital Center of Zagreb, 10 000 Zagreb, Croatia;
| | - Suzana Konjevoda
- Department of Health Studies, University of Zadar, 23 000 Zadar, Croatia;
- Department of Ophthalmology, General Hospital Zadar, 23 000 Zadar, Croatia
| | - Natalija Filipović
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, 21 000 Split, Croatia; (N.K.); (A.R.); (N.F.); (N.P.)
| | - Nikola Pavlović
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, 21 000 Split, Croatia; (N.K.); (A.R.); (N.F.); (N.P.)
| | - Katarina Vukojević
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, 21 000 Split, Croatia; (N.K.); (A.R.); (N.F.); (N.P.)
- Center for Translational Research in Biomedicine, School of Medicine, University of Split, 21 000 Split, Croatia
- Department of Anatomy, School of Medicine, University of Mostar, 88 000 Mostar, Bosnia and Herzegovina
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3
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Yang H, He L, Gong H, Wan C, Ding J, Liao P, Wang X. Identification of novel pathogenic variants of CUBN in patients with isolated proteinuria. Mol Genet Genomic Med 2024; 12:e2353. [PMID: 38488435 PMCID: PMC10941600 DOI: 10.1002/mgg3.2353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 11/29/2023] [Accepted: 12/11/2023] [Indexed: 03/18/2024] Open
Abstract
BACKGROUND Although proteinuria is long recognized as an independent risk factor for progressive chronic kidney diseases, not all forms of proteinuria are detrimental to kidney function, one of which is isolated proteinuria caused by cubilin (CUBN)-specific mutations. CUBN encodes an endocytic receptor, initially found to be responsible for the Imerslund-Gräsbeck syndrome (IGS; OMIM #261100) characterized by a combined phenotype of megaloblastic anemia and proteinuria. METHODS After analyzing their clinical and pathological characterizations, next-generation sequencing for renal disease genes or whole-exome sequencing (WES) was performed on four patients with non-progressive isolated proteinuria. CUBN biallelic pathogenic variants were identified and further analyzed by cDNA-PCR sequencing, immunohistochemistry, minigene assay, and multiple in silico prediction tools, including 3D protein modeling. RESULTS Here, we present four patients with isolated proteinuria caused by CUBN C-terminal biallelic pathogenic variants, all of which showed no typical IGS symptoms, such as anemia and vitamin B12 deficiency. Their urine protein levels fluctuated between +~++ and estimated glomerular filtration rate (eGFR) were normal or slightly higher. Mild mesangial hypercellularity was found in three children's renal biopsies. A homozygous splice-site variant of CUBN (c.6821+3 (IVS44) A>G) was proven to result in the exon 44 skipping and premature translation termination by cDNA sequencing and immunohistochemistry. Compound heterozygous mutations were identified among the other three children, including another novel splice-site variant (c.10764+1 (IVS66) G>A) causing the retention of first 4 nucleotides in intron 66 by minigene assay, two unreported missense mutations (c.4907G>A (p.R1636Q); c. 9095 A>G (p.Y3032C)), and two reported missense mutations in China (c.8938G>A (p.D2980N); c. 9287T>C (p.L3096P)), locating behind the vitamin B12-binding domain, affecting CUB11, CUB16, CUB22, CUB23, and CUB27 domains, respectively. CONCLUSION These results demonstrate that above CUBN mutations may cause non-progressive and isolated proteinuria, expanding the variant spectrum of CUBN and benefiting our understanding of proteinuria and renal function.
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Affiliation(s)
- Huihui Yang
- Department of Nephrology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
| | - Lanfen He
- Department of Nephrology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
| | - Hongjian Gong
- Clinical Research Center, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
| | - Chunhui Wan
- Precision Medical Center, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
| | - Juanjuan Ding
- Department of Nephrology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
| | - Panli Liao
- Department of Nephrology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
| | - Xiaowen Wang
- Department of Nephrology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Center)Tongji Medical College, Huazhong University of Science & TechnologyWuhanChina
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Kingma SDK, Neven J, Bael A, Meuwissen MEC, van den Akker M. Imerslund-Gräsbeck syndrome: a comprehensive review of reported cases. Orphanet J Rare Dis 2023; 18:291. [PMID: 37710296 PMCID: PMC10500774 DOI: 10.1186/s13023-023-02889-x] [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: 01/17/2023] [Accepted: 08/25/2023] [Indexed: 09/16/2023] Open
Abstract
Imerslund-Gräsbeck syndrome (IGS) is a rare autosomal recessive disorder characterized by vitamin B12 malabsorption. Most patients present with non-specific symptoms attributed to vitamin B12 deficiency, and proteinuria. Patients may if untreated, develop severe neurocognitive manifestations. If recognized and treated with sufficient doses of vitamin B12, patients recover completely. We provide, for the first time, an overview of all previously reported cases of IGS. In addition, we provide a complete review of IGS and describe two new patients.
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Affiliation(s)
- Sandra D K Kingma
- Centre for Metabolic Diseases, University Hospital Antwerp, University of Antwerp, Drie Eikenstraat 655, Edegem, Antwerp, 2650, Belgium
- Department of Pediatrics, University Hospital Antwerp, University of Antwerp, Drie Eikenstraat 655, Edegem, 2650, Belgium
- Faculty of medicine and health sciences, University of Antwerp, Antwerp, Belgium
| | - Julie Neven
- Department of Pediatrics, University Hospital Antwerp, University of Antwerp, Drie Eikenstraat 655, Edegem, 2650, Belgium
| | - An Bael
- Faculty of medicine and health sciences, University of Antwerp, Antwerp, Belgium
- Department of Pediatric Nephrology, ZNA Queen Paola Children's Hospital, Lindendreef 1, Antwerp, 2020, Belgium
| | - Marije E C Meuwissen
- Center of Medical Genetics, University Hospital Antwerp, Drie Eikenstraat 655, Edegem, 2650, Belgium
| | - Machiel van den Akker
- Department of Pediatrics, University Hospital Antwerp, University of Antwerp, Drie Eikenstraat 655, Edegem, 2650, Belgium.
- Faculty of medicine and health sciences, University of Antwerp, Antwerp, Belgium.
- Department of Pediatrics, ZNA Queen Paola Children's Hospital, Lindendreef 1, Antwerp, 2020, Belgium.
- Pediatric Hematology and Oncology, Department of Pediatrics, University Hospital Antwerp, Drie Eikenstraat 655, Edegem, Antwerp, 2650, Belgium.
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5
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Clinical and genetic characterization of children with cubilin variants. Pediatr Nephrol 2023; 38:1381-1385. [PMID: 36112210 DOI: 10.1007/s00467-022-05730-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 10/14/2022]
Abstract
BACKGROUND Cubilin is one of the receptor proteins responsible for reabsorption of albumin in proximal tubules and is encoded by the CUBN gene. We aimed to evaluate clinical and genetic characterization of six patients with proteinuria who had CUBN mutations. METHODS Patients' characteristics, serum creatinine, albumin, vitamin B12 levels, urine analysis, spot urine protein/creatinine, microalbumin/creatinine, beta-2 microglobulin/creatinine ratios, estimated glomerular filtration rates (eGFR), treatments, kidney biopsies, and genetic analyses were evaluated. RESULTS Six patients (2 female, 4 male) with an incidental finding of proteinuria were evaluated. Mean admission age and follow-up time were 7.3 ± 2.9 and 6.5 ± 5.6 years, respectively. Serum albumin, creatinine, and eGFR were normal; urine analysis revealed no hematuria, and C3, C4, ANA, and anti-DNA were negative; kidney ultrasonography was normal for all patients. Urine protein/creatinine was 0.9 ± 0.3 mg/mg, and microalbumin was high in all patients. Serum vitamin B12 was low in two patients and normal in four. Kidney biopsy was performed in four patients, three demonstrated normal light microscopy, and there was one focal segmental glomerulosclerosis (FSGS). Genetic tests revealed four homozygous and two compound heterozygous mutations in the C-terminal part of cubilin. All patients had normal eGFR and still had non-nephrotic range proteinuria at last visit. CONCLUSIONS CUBN gene mutations should be considered in patients with isolated non-nephrotic range proteinuria and normal kidney function. Diagnosing these patients, who are thought to have a better prognosis, is important in terms of avoiding unnecessary treatment and predicting prognosis. CUBN gene mutations may also present as FSGS which extends the spectrum of renal manifestation of these patients. A higher resolution version of the Graphical abstract is available as Supplementary information.
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6
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Goto S, Hosojima M, Kabasawa H, Saito A. The endocytosis receptor megalin: From bench to bedside. Int J Biochem Cell Biol 2023; 157:106393. [PMID: 36863658 DOI: 10.1016/j.biocel.2023.106393] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/27/2023] [Indexed: 03/04/2023]
Abstract
The large (∼600 kDa) endocytosis receptor megalin/low-density lipoprotein receptor-related protein 2 is highly expressed at the apical membrane of proximal tubular epithelial cells (PTECs). Megalin plays an important role in the endocytosis of various ligands via interactions with intracellular adaptor proteins, which mediate the trafficking of megalin in PTECs. Megalin mediates the retrieval of essential substances, including carrier-bound vitamins and elements, and impairment of the endocytic process may result in the loss of those substances. In addition, megalin reabsorbs nephrotoxic substances such as antimicrobial (colistin, vancomycin, and gentamicin) or anticancer (cisplatin) drugs and advanced glycation end product-modified or fatty acid-containing albumin. The megalin-mediated uptake of these nephrotoxic ligands causes metabolic overload in PTECs and leads to kidney injury. Blockade or suppression of the megalin-mediated endocytosis of nephrotoxic substances may represent a novel therapeutic strategy for drug-induced nephrotoxicity or metabolic kidney disease. Megalin reabsorbs urinary biomarker proteins such as albumin, α1-microglobulin, β2-microglobulin, and liver-type fatty acid-binding protein; thus, the above-mentioned megalin-targeted therapy may have an effect on the urinary excretion of these biomarkers. We have previously established a sandwich enzyme-linked immunosorbent assay to measure the ectodomain (A-megalin) and full-length (C-megalin) forms of urinary megalin using monoclonal antibodies against the amino- and carboxyl-terminals of megalin, respectively, and reported their clinical usefulness. In addition, there have been reports of patients with novel pathological anti-brush border autoantibodies targeting megalin in the kidney. Even with these breakthroughs in the characterization of megalin, a large number of issues remain to be addressed in future research.
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Affiliation(s)
- Sawako Goto
- Departments of Applied Molecular Medicine, Japan
| | - Michihiro Hosojima
- Departments of Clinical Nutrition Science, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Niigata, Japan
| | - Hideyuki Kabasawa
- Departments of Clinical Nutrition Science, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Niigata, Japan
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Ma L, Peng X, Gong Q. A GDF2 missense mutation potentially involved in the pathogenesis of hereditary hemorrhagic telangiectasia: a case report. J Int Med Res 2023; 51:3000605231159545. [PMID: 36891821 PMCID: PMC10009034 DOI: 10.1177/03000605231159545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023] Open
Abstract
Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disease. ENG and ACVRL1 gene variants account for up to 96% of all cases, while the remaining cases are caused by SMAD4 or GDF2 variants, or by currently undiscovered mutations in coding or non-coding regions. Here, we report a 47-year-old man who presented with duodenal bulb bleeding and chronic anemia. Physical examination also revealed bleeding from the skin and gingiva. His parents were cousins and one brother and one sister died in infancy from anemia and bleeding. Head computed tomography angiography (CTA) revealed a complete fetal posterior cerebral artery located in the left side, and pulmonary CTA showed pulmonary arterial hypertension. The patient was diagnosed with HHT. Peripheral blood was collected for whole-exome sequencing. Sequencing revealed a mutation in the GDF2 gene, which encodes bone morphogenetic protein-9 (BMP-9). The detected variant, c.352A > T(p.Ile118Phe), was predicted to be a neutral polymorphism; however, the patient's plasma BMP-9 levels were greatly reduced; we predicted that this might be caused by the GDF2 variant and might be involved in the HHT pathogenesis. Further research in cell lines and animal models is needed to verify the correlation between this GDF2 variant and the pathogenesis of HHT.
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Affiliation(s)
- Le Ma
- Department of Hematology, Southwest Hospital, First Affiliated Hospital of the Army Medical University, Chongqing 400038, China
| | - Xi Peng
- Department of Hematology, Southwest Hospital, First Affiliated Hospital of the Army Medical University, Chongqing 400038, China
| | - Qiang Gong
- Department of Hematology, Southwest Hospital, First Affiliated Hospital of the Army Medical University, Chongqing 400038, China
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8
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Ran J, Chen Q, Hu Y, Yang P, Yu G, Liao X, Lei J. Isolated Proteinuria Caused by CUBN Gene Mutations: A Case Report and Review of the Literature. Case Rep Nephrol Dial 2023; 13:27-35. [PMID: 37384121 PMCID: PMC10293958 DOI: 10.1159/000530466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 03/27/2023] [Indexed: 06/30/2023] Open
Abstract
Mutations in the cubilin (CUBN) gene commonly cause Imerslund-Gräsbeck syndrome, while isolated proteinuria as a result of CUBN variations is rarely reported. The clinical manifestation is mainly chronic isolated proteinuria in the non-nephrotic range. However, findings to date suggest that isolated proteinuria associated with abnormalities in the CUBN gene is benign and does not affect long-term prognosis of kidney function. We identified 2 patients with isolated proteinuria triggered by compound heterozygous CUBN mutations. Renal functions of both patients remained normal over a 10-year follow-up period, supporting the benign nature of proteinuria caused by CUBN gene variations. Two novel mutation sites were detected, expanding the genotypic spectrum of CUBN variations. In addition, etiology, pathogenesis, clinical manifestations, auxiliary examination, and treatment of the condition were reviewed, with the aim of providing further guidance for clinical management.
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Affiliation(s)
- Jingyang Ran
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Qingsong Chen
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yudong Hu
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Pengfei Yang
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Guiquan Yu
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xiaohui Liao
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Jianrong Lei
- Nephrology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
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9
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Dog-human translational genomics: state of the art and genomic resources. J Appl Genet 2022; 63:703-716. [PMID: 36074326 DOI: 10.1007/s13353-022-00721-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
Abstract
Innovative models for medical research are strongly required nowadays. Convincing evidence supports dog as the most suitable spontaneous model for several human genetic diseases. Decades of studies on dog genome allowed the identification of hundreds of mutations causing genetic disorders, many of which are proposed as counterparts responsible for human diseases. Traditionally, the murine model is the most extensively used in human translational research. However, this species shows large physiological differences from humans, and it is kept under a controlled artificial environment. Conversely, canine genetic disorders often show pathophysiological and clinical features highly resembling the human counterpart. In addition, dogs share the same environment with humans; therefore, they are naturally exposed to many risk factors. Thus, different branches of translational medicine aim to study spontaneously occurring diseases in dogs to provide a more reliable model for human disorders. This review offers a comprehensive overview of the knowledge and resources available today for all the researchers involved in the field of dog-human translational medicine. Some of the main successful examples from dog-human translational genomics are reported, such as the canine association studies which helped to identify the causal mutation in the human counterpart. We also illustrated the ongoing projects aiming to create public canine big datasets. Finally, specific online databases are discussed along with several information resources that can speed up clinical translational research.
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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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Bi Y, Wei H, Nian H, Liu R, Ji W, Liu H, Bao J. Socializing Models During Lactation Alter Colonic Mucosal Gene Expression and Fecal Microbiota of Growing Piglets. Front Microbiol 2022; 13:819011. [PMID: 35875524 PMCID: PMC9301273 DOI: 10.3389/fmicb.2022.819011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 05/30/2022] [Indexed: 11/28/2022] Open
Abstract
The enrichment of the social environment during lactation alleviates the stress of weaned piglets. It is significant to understand how the enriched social environment improves the weaning stress of piglets. RNA sequencing (RNA-seq) of colonic mucosa, 16S rRNA sequencing of feces, and short-chain fatty acids (SCFAs) of colonic content were used to determine the effects of social contact during lactation. In this study, thirty litter lactating piglets were divided into intermittent social contact (ISC) group that contacted with neighbors intermittently, continuous social contact (CSC) group that contacted with neighbors starting at day (D) 14 after birth, and control (CON) group in which piglets were kept in their original litter. The piglets were weaned at D35 and regrouped at D36. The colonic mucosal RNA-seq, fecal microbes, and SCFAs of colonic contents of 63-day-old piglets were analyzed. The results of RNA-seq showed that compared with the CON group, the pathways of digestion and absorption of minerals, protein, and vitamins of piglets were changed in the ISC group, whereas the pathways of retinol metabolism and nitrogen metabolism in the colonic mucosal were affected and stimulated the immune response in the CSC group. Compared with the CON group, the abundances of pernicious microorganisms (Desulfovibrio, Pseudomonas, Brevundimonas, etc.) in the CSC group and pernicious microorganisms (Desulfovibrio, Neisseria, Sutterella, etc.) and beneficial bacteria (Bifidobacterium, Megamonas, and Prevotella_9) in the ISC group were significantly higher (p < 0.05). The abundances of proinflammatory bacteria (Coriobacteriaceae_unclassified, Coprococcus_3, and Ruminococcus_2) in the CSC group were significantly increased (p < 0.05), but the abundances of SCFAs producing bacteria (Lachnospiraceae_UCG-010, Parabacteroides, Anaerotruncus, etc.) and those of anti-inflammatory bacteria (Eubacterium, Parabacteroides, Ruminiclostridium_9, and Alloprevotella) were significantly reduced (p < 0.05) in the CSC group. Compared with the CON group, the concentrations of microbial metabolites, acetate, and propionate in the colonic contents were reduced (p < 0.05) in the ISC group, whereas the concentration of acetate was reduced (p < 0.05) in the CSC group. Therefore, both ISC and CSC during lactation affected the composition of fecal microbes and changed the expression of intestinal mucosal genes related to nutrient metabolism and absorption of piglets.
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Affiliation(s)
- Yanju Bi
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
| | - Haidong Wei
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
| | - Haoyang Nian
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
| | - Runze Liu
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
| | - Wenbo Ji
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
| | - Honggui Liu
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
- Key Laboratory of Swine Facilities Engineering, Ministry of Agriculture and Rural Affairs, Harbin, China
| | - Jun Bao
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, China
- Key Laboratory of Swine Facilities Engineering, Ministry of Agriculture and Rural Affairs, Harbin, China
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12
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Watkins D, Rosenblatt DS. Inherited defects of cobalamin metabolism. VITAMINS AND HORMONES 2022; 119:355-376. [PMID: 35337626 DOI: 10.1016/bs.vh.2022.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cobalamin (vitamin B12) is required for activity of the enzymes methylmalonyl-CoA mutase and methionine synthase in human cells. Inborn errors affecting cobalamin uptake or metabolism are characterized by accumulation of the substrates for these enzymes, methylmalonic acid and homocysteine, in blood and urine. Inborn errors affecting synthesis of the adenosylcobalamin coenzyme required by methylmalonyl-CoA mutase (cblA and cblB) result in isolated methylmalonic aciduria; inborn errors affecting synthesis of the methylcobalamin coenzyme required by methionine synthase (cblE and cblG) result in isolated homocystinuria. Combined methylmalonic aciduria and homocystinuria is seen in patients with impaired intestinal cobalamin absorption (intrinsic factor deficiency, Imerslund-Gräsbeck syndrome) and with defects affecting synthesis of both cobalamin coenzymes (cblC, cblD, cblF and cblJ). A series of disorders caused by pathogenic variant mutations affecting gene regulators (transcription factors) of the MMACHC gene have recently been described (HCFC1 [cblX disorder] and deficiencies of THAP11, and ZNF143 [the cblK disorder]).
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Affiliation(s)
- David Watkins
- Department of Human Genetics, McGill University, The Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
| | - David S Rosenblatt
- Department of Human Genetics, McGill University, The Research Institute of the McGill University Health Centre, Montreal, QC, Canada
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13
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Guéant JL, Guéant-Rodriguez RM, Alpers DH. Vitamin B12 absorption and malabsorption. VITAMINS AND HORMONES 2022; 119:241-274. [PMID: 35337622 DOI: 10.1016/bs.vh.2022.01.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Vitamin B12 is assimilated and transported by complex mechanisms that involve three transport proteins, intrinsic factor (IF), haptocorrin (HC) and transcobalamin (TC) and their respective membrane receptors. Vitamin deficiency is mainly due to inadequate dietary intake in vegans, and B12 malabsorption is related to digestive diseases. This review explores the physiology of vitamin B12 absorption and the mechanisms and diseases that produce malabsorption. In the stomach, B12 is released from food carrier proteins and binds to HC. The degradation of HC by pancreatic proteases and the pH change trigger the transfer of B12 to IF in the duodenum. Cubilin and amnionless are the two components of the receptor that mediates the uptake of B12 in the distal ileum. Part of liver B12 is excreted in bile, and undergoes an enterohepatic circulation. The main causes of B12 malabsorption include inherited disorders (Intrinsic factor deficiency, Imerslund-Gräsbeck disease, Addison's pernicious anemia, obesity, bariatric surgery and gastrectomies. Other causes include pancreatic insufficiency, obstructive Jaundice, tropical sprue and celiac disease, bacterial overgrowth, parasitic infestations, Zollinger-Ellison syndrome, inflammatory bowel diseases, chronic radiation enteritis of the distal ileum and short bowel. The assessment of B12 deficit is recommended in the follow-up of subjects with bariatric surgery. The genetic causes of B12 malabsorption are probably underestimated in adult cases with B12 deficit. Despite its high prevalence in the general population and in the elderly, B12 malabsorption cannot be anymore assessed by the Schilling test, pointing out the urgent need for an equivalent reliable test.
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Affiliation(s)
- Jean-Louis Guéant
- University of Lorraine, INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, Nancy, France; Department of Biochemistry, Molecular Biology, Nutrition, and Metabolism, University Hospital of Nancy, Nancy, France; Department of Hepato-Gastroenterology, University Hospital of Nancy, Nancy, France.
| | - Rosa-Maria Guéant-Rodriguez
- University of Lorraine, INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, Nancy, France; Department of Biochemistry, Molecular Biology, Nutrition, and Metabolism, University Hospital of Nancy, Nancy, France
| | - David H Alpers
- Department of Internal Medicine, Division of Gastroenterology, Washington University School of Medicine, St Louis, MO, United States.
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14
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Issler N, Afonso S, Weissman I, Jordan K, Cebrian-Serrano A, Meindl K, Dahlke E, Tziridis K, Yan G, Robles-López JM, Tabernero L, Patel V, Kesselheim A, Klootwijk ED, Stanescu HC, Dumitriu S, Iancu D, Tekman M, Mozere M, Jaureguiberry G, Outtandy P, Russell C, Forst AL, Sterner C, Heinl ES, Othmen H, Tegtmeier I, Reichold M, Schiessl IM, Limm K, Oefner P, Witzgall R, Fu L, Theilig F, Schilling A, Shuster Biton E, Kalfon L, Fedida A, Arnon-Sheleg E, Ben Izhak O, Magen D, Anikster Y, Schulze H, Ziegler C, Lowe M, Davies B, Böckenhauer D, Kleta R, Falik Zaccai TC, Warth R. A Founder Mutation in EHD1 Presents with Tubular Proteinuria and Deafness. J Am Soc Nephrol 2022; 33:732-745. [PMID: 35149593 PMCID: PMC8970462 DOI: 10.1681/asn.2021101312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/17/2021] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The endocytic reabsorption of proteins in the proximal tubule requires a complex machinery and defects can lead to tubular proteinuria. The precise mechanisms of endocytosis and processing of receptors and cargo are incompletely understood. EHD1 belongs to a family of proteins presumably involved in the scission of intracellular vesicles and in ciliogenesis. However, the relevance of EHD1 in human tissues, in particular in the kidney, was unknown. METHODS Genetic techniques were used in patients with tubular proteinuria and deafness to identify the disease-causing gene. Diagnostic and functional studies were performed in patients and disease models to investigate the pathophysiology. RESULTS We identified six individuals (5-33 years) with proteinuria and a high-frequency hearing deficit associated with the homozygous missense variant c.1192C>T (p.R398W) in EHD1. Proteinuria (0.7-2.1 g/d) consisted predominantly of low molecular weight proteins, reflecting impaired renal proximal tubular endocytosis of filtered proteins. Ehd1 knockout and Ehd1R398W/R398W knockin mice also showed a high-frequency hearing deficit and impaired receptor-mediated endocytosis in proximal tubules, and a zebrafish model showed impaired ability to reabsorb low molecular weight dextran. Interestingly, ciliogenesis appeared unaffected in patients and mouse models. In silico structural analysis predicted a destabilizing effect of the R398W variant and possible inference with nucleotide binding leading to impaired EHD1 oligomerization and membrane remodeling ability. CONCLUSIONS A homozygous missense variant of EHD1 causes a previously unrecognized autosomal recessive disorder characterized by sensorineural deafness and tubular proteinuria. Recessive EHD1 variants should be considered in individuals with hearing impairment, especially if tubular proteinuria is noted.
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Affiliation(s)
- Naomi Issler
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Sara Afonso
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Irith Weissman
- Pediatric Nephrology, Galilee Medical Center, Nahraia, Israel
| | - Katrin Jordan
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | | | - Katrin Meindl
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Eileen Dahlke
- Institute of Anatomy, University of Kiel, Kiel, Germany
| | - Konstantin Tziridis
- Ear, Nose, and Throat Clinic, University Hospital Erlangen, Erlangen, Germany
| | - Guanhua Yan
- Division of Molecular and Cellular Function, University of Manchester, United Kingdom
| | - José M. Robles-López
- Division of Molecular and Cellular Function, University of Manchester, United Kingdom
| | - Lydia Tabernero
- Division of Molecular and Cellular Function, University of Manchester, United Kingdom
| | - Vaksha Patel
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Anne Kesselheim
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Enriko D. Klootwijk
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Horia C. Stanescu
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Simona Dumitriu
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Daniela Iancu
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Mehmet Tekman
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Monika Mozere
- Department of Renal Medicine, University College London, London, United Kingdom
| | | | - Priya Outtandy
- Department of Renal Medicine, University College London, London, United Kingdom
| | | | - Anna-Lena Forst
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | | | | | - Helga Othmen
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Ines Tegtmeier
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Markus Reichold
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | | | - Katharina Limm
- Institute of Functional Genomics, University of Regensburg, Regensburg, Germany
| | - Peter Oefner
- Institute of Functional Genomics, University of Regensburg, Regensburg, Germany
| | - Ralph Witzgall
- Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany
| | - Lifei Fu
- Structural Biology, University of Regensburg, Regensburg, Germany
| | | | - Achim Schilling
- Ear, Nose, and Throat Clinic, University Hospital Erlangen, Erlangen, Germany
| | | | - Limor Kalfon
- Institute of Human Genetics, Galilee Medical Center, Nahraia, Israel
| | - Ayalla Fedida
- Institute of Human Genetics, Galilee Medical Center, Nahraia, Israel
| | | | - Ofer Ben Izhak
- Department of Pathology, Rambam Health Care Campus, Technion Faculty of Medicine, Haifa, Israel
| | - Daniella Magen
- Pediatric Nephrology Institute, Rambam Health Care Campus, Technion Faculty of Medicine, Haifa, Israel
| | | | - Holger Schulze
- Ear, Nose, and Throat Clinic, University Hospital Erlangen, Erlangen, Germany
| | | | - Martin Lowe
- Division of Molecular and Cellular Function, University of Manchester, United Kingdom
| | - Benjamin Davies
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Detlef Böckenhauer
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom
| | - Tzipora C. Falik Zaccai
- The Azrieli Faculty of Medicine, Bar Ilan, Safed, Israel
- Institute of Human Genetics, Galilee Medical Center, Nahraia, Israel
| | - Richard Warth
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
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15
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Kozyraki R, Verroust P, Cases O. Cubilin, the intrinsic factor-vitamin B12 receptor. VITAMINS AND HORMONES 2022; 119:65-119. [PMID: 35337634 DOI: 10.1016/bs.vh.2022.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cubilin (CUBN), the intrinsic factor-vitamin B12 receptor is a large endocytic protein involved in various physiological functions: vitamin B12 uptake in the gut; reabsorption of albumin and maturation of vitamin D in the kidney; nutrient delivery during embryonic development. Cubilin is an atypical receptor, peripherally associated to the plasma membrane. The transmembrane proteins amnionless (AMN) and Lrp2/Megalin are the currently known molecular partners contributing to plasma membrane transport and internalization of Cubilin. The role of Cubilin/Amn complex in the handling of vitamin B12 in health and disease has extensively been studied and so is the role of the Cubilin-Lrp2 tandem in renal pathophysiology. Accumulating evidence strongly supports a role of Cubilin in some developmental defects including impaired closure of the neural tube. Are these defects primarily caused by the dysfunction of a specific Cubilin ligand or are they secondary to impaired vitamin B12 or protein uptake? We will present the established Cubilin functions, discuss the developmental data and provide an overview of the emerging implications of Cubilin in the field of cardiovascular disease and cancer pathogenesis.
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Affiliation(s)
- Renata Kozyraki
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France.
| | - Pierre Verroust
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France
| | - Olivier Cases
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France
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16
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Cubilin and Amnionless Protein are Novel Target Antigens in Anti-Brush Border Antibody Disease. Kidney Int 2022; 101:1063-1068. [PMID: 35276203 DOI: 10.1016/j.kint.2022.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 01/21/2022] [Accepted: 02/08/2022] [Indexed: 11/23/2022]
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17
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Beenken A. Endocytosis Begins inside the Cell. J Am Soc Nephrol 2022; 33:661-662. [PMID: 35256404 PMCID: PMC8970442 DOI: 10.1681/asn.2022020155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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18
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Keegan NP, Wilton SD, Fletcher S. Analysis of Pathogenic Pseudoexons Reveals Novel Mechanisms Driving Cryptic Splicing. Front Genet 2022; 12:806946. [PMID: 35140743 PMCID: PMC8819188 DOI: 10.3389/fgene.2021.806946] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/09/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding pre-mRNA splicing is crucial to accurately diagnosing and treating genetic diseases. However, mutations that alter splicing can exert highly diverse effects. Of all the known types of splicing mutations, perhaps the rarest and most difficult to predict are those that activate pseudoexons, sometimes also called cryptic exons. Unlike other splicing mutations that either destroy or redirect existing splice events, pseudoexon mutations appear to create entirely new exons within introns. Since exon definition in vertebrates requires coordinated arrangements of numerous RNA motifs, one might expect that pseudoexons would only arise when rearrangements of intronic DNA create novel exons by chance. Surprisingly, although such mutations do occur, a far more common cause of pseudoexons is deep-intronic single nucleotide variants, raising the question of why these latent exon-like tracts near the mutation sites have not already been purged from the genome by the evolutionary advantage of more efficient splicing. Possible answers may lie in deep intronic splicing processes such as recursive splicing or poison exon splicing. Because these processes utilize intronic motifs that benignly engage with the spliceosome, the regions involved may be more susceptible to exonization than other intronic regions would be. We speculated that a comprehensive study of reported pseudoexons might detect alignments with known deep intronic splice sites and could also permit the characterisation of novel pseudoexon categories. In this report, we present and analyse a catalogue of over 400 published pseudoexon splice events. In addition to confirming prior observations of the most common pseudoexon mutation types, the size of this catalogue also enabled us to suggest new categories for some of the rarer types of pseudoexon mutation. By comparing our catalogue against published datasets of non-canonical splice events, we also found that 15.7% of pseudoexons exhibit some splicing activity at one or both of their splice sites in non-mutant cells. Importantly, this included seven examples of experimentally confirmed recursive splice sites, confirming for the first time a long-suspected link between these two splicing phenomena. These findings have the potential to improve the fidelity of genetic diagnostics and reveal new targets for splice-modulating therapies.
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Affiliation(s)
- Niall P. Keegan
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
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19
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Yang J, Xu Y, Deng L, Zhou L, Qiu L, Zhang Y, Zhou J. CUBN gene mutations may cause focal segmental glomerulosclerosis (FSGS) in children. BMC Nephrol 2022; 23:15. [PMID: 34979989 PMCID: PMC8725476 DOI: 10.1186/s12882-021-02654-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 12/20/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Imerslund-Gräsbeck Syndrome (IGS) is mainly caused by CUBN gene biallelic mutations. Proteinuria accompanies IGS specific symptoms in about half of the patients, isolated proteinuria is rarely reported. Here we present 3 patients with isolated proteinuria and focal segmental glomerulosclerosis (FSGS) caused by CUBN gene biallelic pathogenic variants. METHOD Whole exome sequencing was performed on three children with isolated proteinuria. CUBN gene biallelic pathogenic variants were found and then verified by sanger sequencing. Their clinical, pathological and molecular genetic characteristics were analyzed and correlated accordingly. RESULTS All three children presented with isolated proteinuria, no megaloblastic anemia. Their urine levels of β2 microglobulin were normal or slightly higher. Renal biopsies showed focal segmental glomerulosclerosis with mild glomerular mesangial hypercellularity, partial effacement of foot processes and podocyte microvillation. Two of them were found to carry compound heterozygous mutations and one homozygous mutation of CUBN gene. Totally four CUBN gene biallelic pathogenic variants were identified, including c.9287 T > C (p.L3096P), c.122 + 1G > A, c.7906C > T (p.R2636*), c.10233G > A (p.W3411*). Except for intron splice-site mutation, all other variants are located in highly conserved sites of CUB domain for binding to albumin. CONCLUSION The results demonstrate that CUBN gene mutations may cause isolated proteinuria pathologically presented as FSGS. Our cases extend the spectrum of renal manifestation and genotype of CUBN gene mutations.
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Affiliation(s)
- Jing Yang
- Department of Pediatrics, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Jiefang Ave. No. 1095, Wuhan, 430030, China
| | - Yongli Xu
- Department of Pediatrics, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Jiefang Ave. No. 1095, Wuhan, 430030, China
| | - Linxia Deng
- Department of Pediatrics, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Jiefang Ave. No. 1095, Wuhan, 430030, China
| | - Luowen Zhou
- Department of Neurosurgery, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Wuhan, China
| | - Liru Qiu
- Department of Pediatrics, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Jiefang Ave. No. 1095, Wuhan, 430030, China
| | - Yu Zhang
- Department of Pediatrics, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Jiefang Ave. No. 1095, Wuhan, 430030, China
| | - Jianhua Zhou
- Department of Pediatrics, Tongji Hospital, Tongji Medical college, Huazhong University of Science and Technology, Jiefang Ave. No. 1095, Wuhan, 430030, China.
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20
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Domingo-Gallego A, Pybus M, Madariaga L, Piñero-Fernández JA, González-Pastor S, López-González M, Simarro-Rueda E, Quintanilla-Mata ML, Matoses-Ruipérez ML, Ejarque-Vila L, Gall ECL, Guirado L, Torra R, Ariceta G, Ars E. Clinical and genetic characterization of a cohort of proteinuric patients with biallelic CUBN variants. Nephrol Dial Transplant 2021; 37:1906-1915. [PMID: 34610128 DOI: 10.1093/ndt/gfab285] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Proteinuria is a well-known risk factor for progressive kidney impairment. Recently, C-terminal cubilin (CUBN) variants have been associated with isolated proteinuria without progression of kidney disease. METHODS Genetic testing of 347 families with proteinuria of suspected monogenic cause was performed by next-generation sequencing of a custom-designed kidney disease gene panel. Families with CUBN biallelic proteinuria-causing variants were studied at the clinical, genetic, laboratory, and pathologic levels. RESULTS Twelve families (15 patients) bearing homozygous or compound heterozygous proteinuria-causing variants in the C-terminal CUBN gene were identified, representing 3.5% of the total cohort. We identified 14 different sequence variants, five of which were novel. The median age at diagnosis of proteinuria was 4 years (range 9 months to 44 years), and in most cases proteinuria was detected incidentally. Thirteen patients had moderate-severe proteinuria at diagnosis without nephrotic syndrome. These patients showed lack of response to angiotensin-converting enzyme inhibitor (ACEi) and angiotensin receptor blocker (ARB) treatment, normal kidney biopsy, and preservation of normal kidney function over time. The two remaining patients presented a more severe phenotype, likely caused by associated comorbidities. CONCLUSIONS Identification of C-terminal pathogenic CUBN variants is diagnostic of an entity characterized by glomerular proteinuria, normal kidney histology, and lack of response to ACEi/ARB treatment. This study adds evidence and increases awareness about albuminuria caused by C-terminal variants in the CUBN gene, which is a benign condition usually diagnosed in childhood with preserved renal function until adulthood.
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Affiliation(s)
- Andrea Domingo-Gallego
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Barcelona, Catalonia, Spain.,Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, Medicine Department, REDinREN, Barcelona, Catalonia, Spain
| | - Marc Pybus
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Barcelona, Catalonia, Spain.,Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, Medicine Department, REDinREN, Barcelona, Catalonia, Spain
| | - Leire Madariaga
- Pediatric Nephrology Department, Cruces University Hospital, Instituto de Investigación Sanitaria Biocruces-Bizkaia, CIBERER, CIBERDEM, Universidad del País Vasco UPV/EHU, Barakaldo, Spain
| | | | - Sara González-Pastor
- Pediatric Nephrology Department, Hospital Universitario Germans Trias i Pujol, Barcelona, Catalonia, Spain
| | - Mercedes López-González
- Pediatric Nephrology Department, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Catalonia, Spain
| | - Esther Simarro-Rueda
- Clinical Analysis Department, Hospital General Universitario de Albacete, Castilla-La Mancha, Spain
| | | | | | - Laia Ejarque-Vila
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Barcelona, Catalonia, Spain
| | - Emilie Cornec-Le Gall
- Service de Néphrologie, Hémodialyse et Transplantation Rénale, Centre Hospitalier Universitaire, Brest, France; UMR1078 Génétique, Génomique Fonctionnelle et Biotechnologies, INSERM, Université de Brest, Brest, France; Université de Bretagne Occidentale, Brest, France
| | - Lluís Guirado
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, Medicine Department, REDinREN, Barcelona, Catalonia, Spain
| | - Roser Torra
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, Medicine Department, REDinREN, Barcelona, Catalonia, Spain
| | - Gema Ariceta
- Pediatric Nephrology Department, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Catalonia, Spain
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Barcelona, Catalonia, Spain.,Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, Medicine Department, REDinREN, Barcelona, Catalonia, Spain
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21
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Holden L, Burke CS, Cullinane D, Keyes TE. Strategies to promote permeation and vectorization, and reduce cytotoxicity of metal complex luminophores for bioimaging and intracellular sensing. RSC Chem Biol 2021; 2:1021-1049. [PMID: 34458823 PMCID: PMC8341117 DOI: 10.1039/d1cb00049g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 04/30/2021] [Indexed: 12/19/2022] Open
Abstract
Transition metal luminophores are emerging as important tools for intracellular imaging and sensing. Their putative suitability for such applications has long been recognised but poor membrane permeability and cytotoxicity were significant barriers that impeded early progress. In recent years, numerous effective routes to overcoming these issues have been reported, inspired in part, by advances and insights from the pharmaceutical and drug delivery domains. In particular, the conjugation of biomolecules but also other less natural synthetic species, from a repertoire of functional motifs have granted membrane permeability and cellular targeting. Such motifs can also reduce cytotoxicity of transition metal complexes and offer a valuable avenue to circumvent such problems leading to promising metal complex candidates for application in bioimaging, sensing and diagnostics. The advances in metal complex probes permeability/targeting are timely, as, in parallel, over the past two decades significant technological advances in luminescence imaging have occurred. In particular, super-resolution imaging is enormously powerful but makes substantial demands of its imaging contrast agents and metal complex luminophores frequently possess the photophysical characteristics to meet these demands. Here, we review some of the key vectors that have been conjugated to transition metal complex luminophores to promote their use in intra-cellular imaging applications. We evaluate some of the most effective strategies in terms of membrane permeability, intracellular targeting and what impact these approaches have on toxicity and phototoxicity which are important considerations in a luminescent contrast or sensing agent.
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Affiliation(s)
- Lorcan Holden
- School of Chemical Sciences, and National Centre for Sensor Research Dublin City University Dublin 9 Ireland
| | - Christopher S Burke
- School of Chemical Sciences, and National Centre for Sensor Research Dublin City University Dublin 9 Ireland
| | - David Cullinane
- School of Chemical Sciences, and National Centre for Sensor Research Dublin City University Dublin 9 Ireland
| | - Tia E Keyes
- School of Chemical Sciences, and National Centre for Sensor Research Dublin City University Dublin 9 Ireland
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22
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Xu J, Lu W. CircSPIDR acts as a tumour suppressor in cervical adenocarcinoma by sponging miR-431-5p and regulating SORCS1 and CUBN expression. Aging (Albany NY) 2021; 13:18340-18359. [PMID: 34326275 PMCID: PMC8351706 DOI: 10.18632/aging.203283] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/19/2021] [Indexed: 01/22/2023]
Abstract
To identify circular RNAs (circRNAs) with tumor suppressor activity against cervical adenocarcinoma, we compared the circRNA levels of cervical adenocarcinoma and normal cervical tissues. We found that circSPIDR was dramatically downregulated in cervical adenocarcinoma tissues. In cervical adenocarcinoma cells, overexpression of circSPIDR reduced cell viability, inhibited colony formation and promoted apoptosis, whereas knockdown of circSPIDR exerted the opposite effects. CircSPIDR overexpression also suppressed the tumorigenicity of cervical adenocarcinoma cells in a xenograft mouse model. CircSPIDR was found to sponge miR-431-5p, thereby de-repressing sortin-related VPS10 domain-containing receptor 1 (SORCS1) and cubilin (CUBN) and inhibiting the development of cervical adenocarcinoma. In clinical cervical samples, circSPIDR expression correlated negatively with miR-431-5p expression and positively with SORCS1 and CUBN expression. These results demonstrated that circSPIDR suppresses cervical adenocarcinoma by competitively binding to miR-431-5p, thus upregulating SORCS1 and CUBN. These findings suggest circSPIDR could serve as a novel therapeutic target for treatment of cervical adenocarcinoma patients.
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Affiliation(s)
- Junfen Xu
- Department of Gynecologic Oncology, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou 310006, Zhejiang, China
| | - Weiguo Lu
- Department of Gynecologic Oncology, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou 310006, Zhejiang, China
- Center of Uterine Cancer Diagnosis & Therapy of Zhejiang Province, Hangzhou 310006, Zhejiang, China
- Zhejiang University Cancer Center, Hangzhou 310006, Zhejiang, China
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23
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Novel CUBN Mutation in a Young Child With Megaloblastic Anemia. J Pediatr Hematol Oncol 2021; 43:e546-e549. [PMID: 33031161 DOI: 10.1097/mph.0000000000001958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 09/03/2020] [Indexed: 10/23/2022]
Abstract
Inherited disorders of cobalamin (Cbl, vitamin B12) metabolism are rare causes of megaloblastic anemia and neurologic abnormalities. More prevalent in certain ethnic groups, these disorders occur despite adequate Cbl intake and usually result from abnormal vitamin cell transport or processing. Cubilin (CUBN, intrinsic factor-cobalamin receptor) is the intestinal receptor for the endocytosis of intrinsic factor-vitamin B12. Its gene is localized to chromosome 10p13 and mutations involving CUBN have been described in patients with congenital megaloblastic anemia. In this report, we describe a novel CUBN pathogenic variant in a child with megaloblastic anemia.
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24
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Elshinawy M, Gao HH, Al-Nabhani DM, Al-Thihli KA. Clinical and molecular characteristics of imerslund-gräsbeck syndrome: First report of a novel Frameshift variant in Exon 11 of AMN gene. Int J Lab Hematol 2021; 43:1009-1015. [PMID: 33491342 DOI: 10.1111/ijlh.13473] [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: 06/11/2020] [Revised: 12/06/2020] [Accepted: 12/30/2020] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Imerslund-Gräsbeck syndrome (IGS) is a rare autosomal-recessive disorder characterized by selective vitamin B12 malabsorption, megaloblastic anemia, and proteinuria. The precise incidence of this disorder is unknown in the Middle East and Arab countries. The disease is caused by a homozygous variant in either AMN or CUBN genes. In addition, some compound heterozygous variants are reported. METHODS Clinical and laboratory data of patients diagnosed with IGS in Oman were retrospectively collected. Mutation analysis for all genes involved in vitamin B12/folic acid metabolism and megaloblastic anemia was conducted using next-generation sequencing (NGS). RESULTS Three siblings (2 girls and a boy) have been diagnosed with the condition. They exhibit a phenotypic variability with different age of presentation and different spectrum of disease. All patients harbor a novel biallelic frameshift mutation in exon 11 of AMN gene (p.Pro409Glyfs*), which was not reported previously in the literature. Both parents are heterozygotes for the same variant. All patients responded well to vitamin B12 parenteral therapy, but proteinuria persisted. CONCLUSION In communities with high incidence of consanguinity, cases of early-onset vitamin B12 deficiency should be thoroughly investigated to explore the possibility of Imerslund-Gräsbeck syndrome and other vitamin B12-related hereditary disorders. Further local and regional studies are highly recommended.
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Affiliation(s)
- Mohamed Elshinawy
- Department of Child Health, Pediatric Hematology/Oncology, Sultan Qaboos University Hospital, Muscat, Oman.,Department of Pediatrics, Pediatric Hematology/Oncology, Faculty of Medicine, University of Alexandria, Alexandria, Egypt
| | | | - Dana M Al-Nabhani
- Department of Nephrology, Sultan Qaboos University Hospital, Muscat, Oman
| | - Khalid A Al-Thihli
- Genetic and developmental Medicine Department, Sultan Qaboos University Hospital, Muscat, Oman
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25
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Abstract
Albuminuria acts as a marker of progressive chronic kidney disease and as an indicator for initiation of hypertension treatment via modulation of the renin-angiotensin-aldosterone system with angiotensin receptor blockers or angiotensin-converting enzyme inhibitors. However, the true significance of albuminuria has yet to be fully defined. Is it merely a marker of underlying pathophysiology, or does it play a causal role in the progression of kidney disease? The answer remains under debate. In this issue of the JCI, Bedin et al. used next-generation sequencing data to identify patients with chronic proteinuria who had biallelic variants in the cubilin gene (CUBN). Through investigation of these pathogenic mutations in CUBN, the authors have further illuminated the clinical implications of albuminuria.
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26
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Urae S, Harita Y, Udagawa T, Ode KL, Nagahama M, Kajiho Y, Kanda S, Saito A, Ueda HR, Nangaku M, Oka A. A cellular model of albumin endocytosis uncovers a link between membrane and nuclear proteins. J Cell Sci 2020; 133:jcs242859. [PMID: 32482797 DOI: 10.1242/jcs.242859] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/20/2020] [Indexed: 12/21/2022] Open
Abstract
Cubilin (CUBN) and amnionless (AMN), expressed in kidney and intestine, form a multiligand receptor complex called CUBAM that plays a crucial role in albumin absorption. To date, the mechanism of albumin endocytosis mediated by CUBAM remains to be elucidated. Here, we describe a quantitative assay to evaluate albumin uptake by CUBAM using cells expressing full-length CUBN and elucidate the crucial roles of the C-terminal part of CUBN and the endocytosis signal motifs of AMN in albumin endocytosis. We also demonstrate that nuclear valosin-containing protein-like 2 (NVL2), an interacting protein of AMN, is involved in this process. Although NVL2 was mainly localized in the nucleolus in cells without AMN expression, it was translocated to the extranuclear compartment when coexpressed with AMN. NVL2 knockdown significantly impaired internalization of the CUBN-albumin complex in cultured cells, demonstrating an involvement of NVL2 in endocytic regulation. These findings uncover a link between membrane and nucleolar proteins that is involved in endocytic processes.
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Affiliation(s)
- Seiya Urae
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
- Division of Nephrology and Endocrinology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Yutaka Harita
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Tomohiro Udagawa
- Department of Pediatrics and Developmental Biology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Koji L Ode
- Department of Systems Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Masami Nagahama
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose-shi, Tokyo 204-8588, Japan
| | - Yuko Kajiho
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Shoichiro Kanda
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Akihiko Saito
- Department of Applied Molecular Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata-shi, Niigata 951-8510, Japan
| | - Hiroki R Ueda
- Department of Systems Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan
- Laboratory for Synthetic Biology, RIKEN Center for Biosystems Dynamics Research, Wako-shi, Saitama 351-0198, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Akira Oka
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
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27
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Gurlek Gokcebay D, Akpinar Tekgunduz S, Cavdarli B. Imerslund-Gräsbeck Syndrome presenting with microangiopathic hemolytic anemia in a child. Eur J Med Genet 2020; 63:103880. [PMID: 32045704 DOI: 10.1016/j.ejmg.2020.103880] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 02/03/2020] [Accepted: 02/07/2020] [Indexed: 11/24/2022]
Abstract
Imerslund-Gräsbeck Syndrome is a rare autosomal recessive disorder characterized by proteinuria and selective malabsorption of cobalamin. Deficiency of cobalamin can lead to megaloblastic anemia, pancytopenia and even "pseudo"-thrombotic microangiopathy (TMA). Signs of mechanical hemolysis on peripheral blood smear, elevated lactate dehydrogenase and thrombocytopenia are common findings of TMA. We report a child presenting with TMA features with cobalamin deficiency. Because of her family history of vitamin B12 deficiency and proteinuria, the performed genetic analysis revealed that an Imerslund-Gräsbeck Syndrome with the detection of a homozygous mutation in AMN gene.
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Affiliation(s)
- Dilek Gurlek Gokcebay
- University of Health Sciences Kecioren Training and Research Hospital, Department of Pediatric Hematology, Turkey.
| | - Sibel Akpinar Tekgunduz
- University of Health Sciences Kecioren Training and Research Hospital, Department of Pediatric Hematology, Turkey
| | - Busranur Cavdarli
- University of Health Sciences Ankara Numune Training and Research Hospital, Department of Medical Genetics, Turkey
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28
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Xing K, Qi X, Ni H, Wang X, Guo Y, Sheng X. Transcriptional analyses of endometrial caruncles in sheep with in vivo / in vitro produced embryos during the peri-implantation period. Reprod Biol 2019; 19:404-411. [PMID: 31806577 DOI: 10.1016/j.repbio.2019.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/22/2019] [Accepted: 09/29/2019] [Indexed: 12/31/2022]
Abstract
In vitro fertilization (IVF) for ovine embryos is strongly associated with low pregnancy rates and negative effects on embryonic and postnatal development, but the mechanisms remain unclear. We aimed to identify genes essential for successful implantation of IVF embryos in sheep by species-specific microarray analysis. Differential gene expression analysis between caruncles and intercaruncle sites of the ovine uterus with in vivo (IVV) -produced embryos on day 10 of pregnancy found 43 differentially expressed genes (DEGs) with at least a 2-fold change, such as coiled-coil domain-containing 152 (CCDC152) and pregnancy-associated plasma protein A (PAPPA). Gene ontology analysis revealed these DEGs were related to cell proliferation, the immune system process, localization and response to stimulus. Moreover, we identified 93 DEGs in endometrial caruncles with IVV- versus in vitro (IVT)-produced embryos on days 12, 14 and 16 of pregnancy, including prostaglandin-endoperoxide synthase 2 (PTGS2) and cubilin (CUBN). GO analysis revealed that these DEGs were related to cell adhesion, cell proliferation, embryo implantation, embryonic morphogenesis, the immune system process and localization. Two DEGs (PAPPA and RSAD2) in caruncle versus intercaruncle sites at day 10 were also differentially expressed between the IVV and IVT groups at the three implantation stages. Self-organizing feature map cluster analysis of transcript profiles during embryo implantation revealed different gene expression patterns between the IVV and IVT groups. In conclusion, this study identified many genes that may be associated with mechanisms underlying IVF-induced ovine embryo implantation failure during the peri-implantation period, and such genes provide potential candidates for further study.
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Affiliation(s)
- Kai Xing
- College of Animal Science and Technology, Beijing University of Agriculture, Beijing, 102206, China
| | - Xiaolong Qi
- College of Animal Science and Technology, Beijing University of Agriculture, Beijing, 102206, China
| | - Hemin Ni
- College of Animal Science and Technology, Beijing University of Agriculture, Beijing, 102206, China
| | - Xiangguo Wang
- College of Animal Science and Technology, Beijing University of Agriculture, Beijing, 102206, China
| | - Yong Guo
- College of Animal Science and Technology, Beijing University of Agriculture, Beijing, 102206, China
| | - Xihui Sheng
- College of Animal Science and Technology, Beijing University of Agriculture, Beijing, 102206, China.
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29
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Brito A, Habeych E, Silva-Zolezzi I, Galaffu N, Allen LH. Methods to assess vitamin B12 bioavailability and technologies to enhance its absorption. Nutr Rev 2019; 76:778-792. [PMID: 29931214 DOI: 10.1093/nutrit/nuy026] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Vitamin B12 (B-12) deficiency is still relatively common in low-, medium-, and high-income countries, mainly because of dietary inadequacy and, to a lesser extent, malabsorption. This narrative review is based on a systematic search of evidence on methods to assess B-12 bioavailability and technologies to enhance its absorption. A total of 2523 scientific articles identified in PubMed and 1572 patents identified in Orbit Intelligence were prescreened. Among the reviewed methods, Schilling's test and/or its food-based version (using cobalamin-labeled egg yolk) were used for decades but have been discontinued, largely because they required radioactive cobalt. The qualitative CobaSorb test, based on changes in circulating holo-transcobalamin before and after B-12 administration, and the 14C-labeled B-12 test for quantitative measurement of absorption of a low-dose radioactive tracer are currently the best available methods. Various forms of B-12 co-formulated with chemical enhancers (ie, salcaprozate sodium, 8-amino caprylate) or supplied via biotechnological methods (ie, microbiological techniques, plant cells expressing cobalamin binding proteins), encapsulation techniques (ie, emulsions, use of chitosan particles), and alternative routes of administration (ie, intranasal, transdermal administration) were identified as potential technologies to enhance B-12 absorption in humans. However, in most cases the evidence of absorption enhancement is limited.
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Affiliation(s)
- Alex Brito
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | | | | | | | - Lindsay H Allen
- United States Department of Agriculture, Agricultural Research Service, Western Human Nutrition Research Center, Davis, California, USA
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30
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Ciancio JIR, Furman M, Banka S, Grunewald S. Profound vitamin D deficiency in four siblings with Imerslund-Grasbeck syndrome with homozygous CUBN mutation. JIMD Rep 2019; 49:43-47. [PMID: 31497480 PMCID: PMC6718117 DOI: 10.1002/jmd2.12072] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 11/16/2022] Open
Abstract
Imerslund-Grasbeck syndrome (IGS, OMIM 261100) is a rare autosomal recessive disease characterized by vitamin B12 malabsorption resulting in megaloblastic anemia and asymptomatic proteinuria. IGS is caused by bi-allelic mutations in either CUBN or AMN that respectively encode the cubilin and amnionless subunits of the cobalamin-intrinsic factor receptor. We report four siblings (three boys, one girl) of non-consanguineous parents of Jewish background, aged 10 months to 12 years, with homozygous CUBN frameshift c.2614_2615deIGA p.(Asp872LeufisTer3) mutation and typical features of IGS. The two older brothers presented in early infancy with lethargy, mouth ulcerations, eosinophilic enterocolitis, megaloblastic anemia and failure to thrive. Investigations revealed low serum cobalamin levels. Intramuscular hydroxycobalamin supplementation resulted in dramatic resolution of all symptoms including lethargy. A positive impact on their growth curve was seen. Prospective early treatment in the younger siblings prevented these manifestations. Proteinuria with proximal tubulopathy was seen in all patients, plasma protein level and renal function were normal. All children had pronounced vitamin D deficiency and required high doses of oral supplementation. Vitamin B12 treatment could be individually adjusted; requirement decreased with age. Tubulopathy showed improvement over time. Low vitamin D could be explained by cubilin being involved in reabsorption of vitamin carriers.
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Affiliation(s)
- Jose I. R. Ciancio
- Metabolic Medicine DepartmentGreat Ormond Street Hospital for Children NHS Foundation TrustLondonUK
| | - Mark Furman
- Consultant Paediatric GastroenterologistRoyal Free HospitalLondonUK
| | - Siddharth Banka
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and HealthThe University of ManchesterManchesterUK
- Manchester Centre for Genomic Medicine, St. Mary's HospitalManchester University, NHS Foundation Trust, Health Innovation ManchesterManchesterUK
| | - Stephanie Grunewald
- Metabolic Medicine DepartmentGreat Ormond Street Hospital for Children NHS Foundation TrustLondonUK
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31
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Jayasinghe K, White SM, Kerr PG, MacGregor D, Stark Z, Wilkins E, Simons C, Mallett A, Quinlan C. Isolated proteinuria due to CUBN homozygous mutation - challenging the investigative paradigm. BMC Nephrol 2019; 20:330. [PMID: 31438875 PMCID: PMC6704575 DOI: 10.1186/s12882-019-1474-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 07/19/2019] [Indexed: 11/25/2022] Open
Abstract
Background Proteinuria is a common clinical presentation, the diagnostic workup for which involves many non-invasive and invasive investigations. We report on two siblings that highlight the clinically relevant functional role of cubulin for albumin resorption in the proximal tubule and supports the use of genomic sequencing early in the diagnostic work up of patients who present with proteinuria. Case presentation An 8-year-old boy was referred with an incidental finding of proteinuria. All preliminary investigations were unremarkable. Further assessment revealed consanguineous family history and a brother with isolated proteinuria. Renal biopsy demonstrated normal light microscopy and global glomerular basement membrane thinning on electron microscopy. Chromosomal microarray revealed long continuous stretches of homozygosity (LCSH) representing ~ 4.5% of the genome. Shared regions of LCSH between the brothers were identified and their further research genomic analysis implicated a homozygous stop-gain variant in CUBN (10p12.31). Conclusions CUBN mutations have been implicated as a hereditary cause of megaloblastic anaemia and variable proteinuria. This is the second reported family with isolated proteinuria due to biallelic CUBN variants in the absence of megaloblastic anaemia, demonstrating the ability of genomic testing to identify genetic causes of nephropathy within expanding associated phenotypic spectra. Genomic sequencing, undertaken earlier in the diagnostic trajectory, may reduce the need for invasive investigations and the time to definitive diagnosis for patients and families.
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Affiliation(s)
- Kushani Jayasinghe
- Department of Nephrology, Monash Medical Centre, Melbourne, Australia.,Monash University, Melbourne, Australia.,Murdoch Children's Research Institute, Melbourne, Australia.,The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia
| | - Susan M White
- The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Victoria, Australia.,Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Australia
| | - Peter G Kerr
- Department of Nephrology, Monash Medical Centre, Melbourne, Australia.,Monash University, Melbourne, Australia
| | - Duncan MacGregor
- Department of Pathology, Royal Children's Hospital, Melbourne, Australia
| | - Zornitza Stark
- Murdoch Children's Research Institute, Melbourne, Australia.,The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Victoria, Australia.,Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Australia
| | - Ella Wilkins
- Murdoch Children's Research Institute, Melbourne, Australia.,The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia.,Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Australia
| | - Cas Simons
- Murdoch Children's Research Institute, Melbourne, Australia.,The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia
| | - Andrew Mallett
- Murdoch Children's Research Institute, Melbourne, Australia.,The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia.,Kidney Health Service and Conjoint Renal Research Laboratory, Royal Brisbane and Women's Hospital, Brisbane, Australia.,Institute for Molecular Bioscience and Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Catherine Quinlan
- Murdoch Children's Research Institute, Melbourne, Australia. .,The KidGen Collaborative, Australian Genomics Health Alliance, Victoria, Australia. .,Department of Paediatric Nephrology, Royal Children's Hospital, 50 Flemington Street, Parkville, Australia.
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32
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Perea-Gomez A, Cases O, Lelièvre V, Pulina MV, Collignon J, Hadjantonakis AK, Kozyraki R. Loss of Cubilin, the intrinsic factor-vitamin B12 receptor, impairs visceral endoderm endocytosis and endodermal patterning in the mouse. Sci Rep 2019; 9:10168. [PMID: 31308417 PMCID: PMC6629654 DOI: 10.1038/s41598-019-46559-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 06/26/2019] [Indexed: 11/17/2022] Open
Abstract
The visceral endoderm is a polarized epithelial monolayer necessary for early embryonic development in rodents. A key feature of this epithelium is an active endocytosis and degradation of maternal nutrients, in addition to being the source of various signaling molecules or inhibitors required for the differentiation and patterning of adjacent embryonic tissues. Endocytosis across the visceral endoderm epithelium involves specific cell surface receptors and an extensive sub-membrane vesicular system with numerous apical vacuoles/lysosomes. We previously reported that Cubilin, the endocytic receptor for intrinsic factor-vitamin B12, albumin and apolipoproteinA-I/HDL allows maternal nutrient uptake by the visceral endoderm. In the present study, we show that the germline ablation of Cubilin impairs endodermal and mesodermal patterning, and results in developmental arrest at gastrulation. Notably, visceral endoderm dispersal is impeded in Cubilin null embryos. We further confirm the essential role of Cubilin in nutrient internalization by the early visceral endoderm and highlight its involvement in the formation of apical vacuoles. Our results reveal essential roles for Cubilin in early embryonic development, and suggest that in addition to its nutritive function, Cubilin sustains signaling pathways involved in embryonic differentiation and patterning.
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Affiliation(s)
- Aitana Perea-Gomez
- Institut Jacques Monod, Université de Paris, CNRS, Paris, F-75013, France.,Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - Olivier Cases
- Centre de Recherche des Cordeliers, INSERM, UMRS-1138, Université de Paris, Paris, F-75006, France
| | - Vincent Lelièvre
- CNRS UPR 3212, INCI, 5 rue Blaise Pascal, F-67084, Strasbourg, France
| | - Maria V Pulina
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, USA.,The Rockefeller University, New York, USA
| | - Jérôme Collignon
- Institut Jacques Monod, Université de Paris, CNRS, Paris, F-75013, France
| | - Anna-Katerina Hadjantonakis
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Renata Kozyraki
- Centre de Recherche des Cordeliers, INSERM, UMRS-1138, Université de Paris, Paris, F-75006, France.
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33
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Froese DS, Fowler B, Baumgartner MR. Vitamin B 12 , folate, and the methionine remethylation cycle-biochemistry, pathways, and regulation. J Inherit Metab Dis 2019; 42:673-685. [PMID: 30693532 DOI: 10.1002/jimd.12009] [Citation(s) in RCA: 198] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/27/2018] [Accepted: 10/19/2018] [Indexed: 12/16/2022]
Abstract
Vitamin B12 (cobalamin, Cbl) is a nutrient essential to human health. Due to its complex structure and dual cofactor forms, Cbl undergoes a complicated series of absorptive and processing steps before serving as cofactor for the enzymes methylmalonyl-CoA mutase and methionine synthase. Methylmalonyl-CoA mutase is required for the catabolism of certain (branched-chain) amino acids into an anaplerotic substrate in the mitochondrion, and dysfunction of the enzyme itself or in production of its cofactor adenosyl-Cbl result in an inability to successfully undergo protein catabolism with concomitant mitochondrial energy disruption. Methionine synthase catalyzes the methyl-Cbl dependent (re)methylation of homocysteine to methionine within the methionine cycle; a reaction required to produce this essential amino acid and generate S-adenosylmethionine, the most important cellular methyl-donor. Disruption of methionine synthase has wide-ranging implications for all methylation-dependent reactions, including epigenetic modification, but also for the intracellular folate pathway, since methionine synthase uses 5-methyltetrahydrofolate as a one-carbon donor. Folate-bound one-carbon units are also required for deoxythymidine monophosphate and de novo purine synthesis; therefore, the flow of single carbon units to each of these pathways must be regulated based on cellular needs. This review provides an overview on Cbl metabolism with a brief description of absorption and intracellular metabolic pathways. It also provides a description of folate-mediated one-carbon metabolism and its intersection with Cbl at the methionine cycle. Finally, a summary of recent advances in understanding of how both pathways are regulated is presented.
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Affiliation(s)
- D Sean Froese
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Brian Fowler
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Matthias R Baumgartner
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
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van Rensburg SJ, Peeters AV, van Toorn R, Schoeman J, Moremi KE, van Heerden CJ, Kotze MJ. Identification of an iron-responsive subtype in two children diagnosed with relapsing-remitting multiple sclerosis using whole exome sequencing. Mol Genet Metab Rep 2019; 19:100465. [PMID: 30963028 PMCID: PMC6434495 DOI: 10.1016/j.ymgmr.2019.100465] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 03/16/2019] [Accepted: 03/16/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Multiple sclerosis is a disorder related to demyelination of axons. Iron is an essential cofactor in myelin synthesis. Previously, we described two children (males of mixed ancestry) with relapsing-remitting multiple sclerosis (RRMS) where long-term remission was achieved by regular iron supplementation. A genetic defect in iron metabolism was postulated, suggesting that more advanced genetic studies could shed new light on disease pathophysiology related to iron. METHODS Whole exome sequencing (WES) was performed to identify causal pathways. Blood tests were performed over a 10 year period to monitor the long-term effect of a supplementation regimen. Clinical wellbeing was assessed quarterly by a pediatric neurologist and regular feedback was obtained from the schoolteachers. RESULTS WES revealed gene variants involved in iron absorption and transport, in the transmembrane protease, serine 6 (TMPRSS6) and transferrin (TF) genes; multiple genetic variants in CUBN, which encodes cubilin (a receptor involved in the absorption of vitamin B12 as well as the reabsorption of transferrin-bound iron and vitamin D in the kidneys); SLC25A37 (involved in iron transport into mitochondria) and CD163 (a scavenger receptor involved in hemorrhage resolution). Variants were also found in COQ3, involved with synthesis of Coenzyme Q10 in mitochondria. Neither of the children had the HLA-DRB1*1501 allele associated with increased genetic risk for MS, suggesting that the genetic contribution of iron-related genetic variants may be instrumental in childhood MS. In both children the RRMS has remained stable without activity over the last 10 years since initiation of nutritional supplementation and maintenance of normal iron levels, confirming the role of iron deficiency in disease pathogenesis in these patients. CONCLUSION Our findings highlight the potential value of WES to identify heritable risk factors that could affect the reabsorption of transferrin-bound iron in the kidneys causing sustained iron loss, together with inhibition of vitamin B12 absorption and vitamin D reabsorption (CUBN) and iron transport into mitochondria (SLC25A37) as the sole site of heme synthesis. This supports a model for RRMS in children with an apparent iron-deficient biochemical subtype of MS, with oligodendrocyte cell death and impaired myelination possibly caused by deficits of energy- and antioxidant capacity in mitochondria.
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Key Words
- CNS, central nervous system
- CoQ, Coenzyme Q
- DFO, desferroxamine mesylate
- DIS, dissemination in space
- DIT, dissemination in time
- DMT, disease modifying therapy
- EDSS, Expanded Disability Status Scale
- ETC, electron transport chain
- GWAS, genome-wide association study
- Genetic variants
- HDL, high density lipoprotein
- HERV-W, human endogenous retrovirus W
- HLA, human leukocyte antigen
- HREC, human research ethics committee
- IPMSSG, International Pediatric Multiple Sclerosis Study Group
- IRE, iron-response element
- Iron deficiency
- MGA1, juvenile hereditary megaloblastic anemia 1
- MRI, magnetic resonance imaging
- MS, Multiple sclerosis
- MSRV, MS-associated retrovirus
- MST1R, macrophage stimulating-1 receptor
- Mitochondria
- Oxidative stress
- PSGT, pathology supported genetic testing
- Pediatric onset multiple sclerosis
- ROS, reactive oxygen species
- RRMS, relapsing-remitting MS
- SAMe, S-adenosyl methionine
- SDHB, iron-protein subunit of Complex II
- TF, transferrin
- TMPRSS6, transmembrane protease, serine 6
- WES, whole exome sequencing
- Whole exome sequencing
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Affiliation(s)
- Susan J. van Rensburg
- Division of Chemical Pathology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Armand V. Peeters
- Division of Anatomical Pathology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Ronald van Toorn
- Paediatric Medicine and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Johan Schoeman
- Paediatric Medicine and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Kelebogile E. Moremi
- Division of Chemical Pathology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Carel J. van Heerden
- Central Analytical Facility (CAF), DNA Sequencing Unit, Stellenbosch University, Stellenbosch, South Africa
| | - Maritha J. Kotze
- Division of Chemical Pathology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, National Health Laboratory Service (NHLS), Cape Town, South Africa
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Gravotta D, Perez Bay A, Jonker CTH, Zager PJ, Benedicto I, Schreiner R, Caceres PS, Rodriguez-Boulan E. Clathrin and clathrin adaptor AP-1 control apical trafficking of megalin in the biosynthetic and recycling routes. Mol Biol Cell 2019; 30:1716-1728. [PMID: 31091172 PMCID: PMC6727755 DOI: 10.1091/mbc.e18-12-0811] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Megalin (gp330, LRP-2) is a protein structurally related to the low-density lipoprotein receptor family that displays a large luminal domain with multiligand binding properties. Megalin localizes to the apical surface of multiple epithelia, where it participates in endocytosis of a variety of ligands performing roles important for development or homeostasis. We recently described the apical recycling pathway of megalin in Madin–Darby canine kidney (MDCK) cells and found that it is a long-lived, fast recycling receptor with a recycling turnover of 15 min and a half-life of 4.8 h. Previous work implicated clathrin and clathrin adaptors in the polarized trafficking of fast recycling basolateral receptors. Hence, here we study the role of clathrin and clathrin adaptors in megalin’s apical localization and trafficking. Targeted silencing of clathrin or the γ1 subunit of clathrin adaptor AP-1 by RNA interference in MDCK cells disrupted apical localization of megalin, causing its redistribution to the basolateral membrane. In contrast, silencing of the γ2 subunit of AP-1 had no effect on megalin polarity. Trafficking assays we developed using FM4-HA-miniMegalin-GFP, a reversible conditional endoplasmic reticulum–retained chimera, revealed that clathrin and AP-1 silencing disrupted apical sorting of megalin in both biosynthetic and recycling routes. Our experiments demonstrate that clathrin and AP-1 control the sorting of an apical transmembrane protein.
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Affiliation(s)
- Diego Gravotta
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
| | - Andres Perez Bay
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
| | - Caspar T H Jonker
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
| | - Patrick J Zager
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
| | - Ignacio Benedicto
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
| | - Ryan Schreiner
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
| | - Paulo S Caceres
- Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY 10065
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Genetic polymorphisms in MTR are associated with non-syndromic congenital heart disease from a family-based case-control study in the Chinese population. Sci Rep 2019; 9:5065. [PMID: 30911047 PMCID: PMC6433945 DOI: 10.1038/s41598-019-41641-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 03/11/2019] [Indexed: 11/24/2022] Open
Abstract
Genetic polymorphisms of folate pathway genes have been reported to be associated with congenital heart diseases (CHDs); however, the results remain conflicting. We conducted a family-based case-control study, which included160 CHD case-parent triads and 208 control-parent triads to explore the association of 18 genetic variants of seven folate metabolism-related genes with the risk of CHDs. The MTR C allele of rs1770449 (OR = 1.961, 95%CI: 1.379–2.788) and the MTR A allele of rs1050993 (OR = 1.994, 95%CI: 1.401–2.839) in infants were associated with an increased risk of CHDs. Over-transmission of SNPs rs1770449 and rs1050993 and haplotype CAA (rs1770449-rs1805087-rs1050993) in MTR were detected in total CHDs. The above mentioned associations of MTR with CHDs were also observed in septal defects and conotruncal heart defects subgroups. Without maternal periconceptional folate intake, the risk of CHDs among women carrying the rs1770449 “CT or CC” genotype or the rs1050993 “AG or AA” genotype in MTR was 3.262(95%CI: 1.656–6.429) or 3.263(95%CI: 1.656–6.429) times greater than the aOR in women carrying wild genotype, respectively. Our study suggests that MTR polymorphisms (rs1770449 and rs1050993) may be associated with the risk of CHDs and modify the relation between maternal folate intake and CHDs.
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Pacitto A, Prontera P, Stangoni G, Stefanelli M, Ceppi S, Cerri C, Gurdo G, Mencarelli A, Esposito S. Imerslund-Gräsbeck Syndrome in an Infant with a Novel Intronic Variant in the AMN Gene: A Case Report. Int J Mol Sci 2019; 20:ijms20030527. [PMID: 30691194 PMCID: PMC6387074 DOI: 10.3390/ijms20030527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 01/09/2019] [Accepted: 01/15/2019] [Indexed: 11/25/2022] Open
Abstract
Imerslund-Gräsbeck syndrome (IGS) is a rare autosomal recessive disorder clinically characterized by megaloblastic anemia, benign mild proteinuria, and other nonspecific symptoms. Several pathogenetic variants in the amnionless (AMN) or cubilin (CUBN) genes have been described in IGS. We describe a case of IGS with urinary tract infection and mild but persistent proteinuria at onset in an 11-month-old female child. With the appearance of macrocytic anemia, aphthous stomatitis, and neurological signs, IGS was clinically suspected, and vitamin B12 parenteral therapy was started. Sequence analysis showed the presence of a novel intronic variant c.513+5G>A of AMN, never before described in the literature, that was in compound heterozygosity with the known pathogenetic variant c.1006+34_1007-31del. Analysis extension to the parents revealed the presence of variant c.1006+34_1007-31 in the father and c.513+5G>A in the mother. In the present case with IGS, the novel intronic variant of AMN was identified in “trans” with a known pathogenic variant (c.1006-31 del) and the new variant was interpreted to be pathogenetic since it was not found in the public database of polymorphisms and because it was predicted to alter a donor splicing site. Our case underlines the relevance in detecting certain subtle symptoms, such as mild but persistent proteinuria associated with megaloblastic anemia, to reach a correct diagnosis of a rare but treatable disorder.
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Affiliation(s)
- Alessandra Pacitto
- Pediatric Clinic, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Paolo Prontera
- Medical Genetics Unit, Santa Maria della Misericordia Hospital, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Gabriela Stangoni
- Medical Genetics Unit, Santa Maria della Misericordia Hospital, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Maurizio Stefanelli
- Pediatric Clinic, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Stefania Ceppi
- Pediatric Clinic, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Carla Cerri
- Pediatric Oncohematology Unit, Santa Maria della Misericordia Hospital, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Grazia Gurdo
- Pediatric Oncohematology Unit, Santa Maria della Misericordia Hospital, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Annalisa Mencarelli
- Pediatric Clinic, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Piazza Menghini 1, 06129 Perugia, Italy.
| | - Susanna Esposito
- Pediatric Clinic, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Piazza Menghini 1, 06129 Perugia, Italy.
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Fyfe JC, Hemker SL, Frampton A, Raj K, Nagy PL, Gibbon KJ, Giger U. Inherited selective cobalamin malabsorption in Komondor dogs associated with a CUBN splice site variant. BMC Vet Res 2018; 14:418. [PMID: 30591068 PMCID: PMC6309081 DOI: 10.1186/s12917-018-1752-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/19/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Three Komondor dogs in a small family and 3 sporadic cases exhibited a constellation of signs that included juvenile-onset of failure-to-thrive, inappetence, vomiting and/or diarrhea, and weakness. In each we documented dyshematopoiesis, increased anion gap, methylmalonic acidemia/-uria, and serum cobalamin deficiency. Urine protein electrophoresis demonstrated excretion of cubam ligands. All clinical signs and metabolic abnormalities, except proteinuria, were reversed by regular parenteral cobalamin administration. The pattern of occurrence and findings in the disorder suggested an autosomal recessive inheritance of cobalamin malabsorption with proteinuria, a condition in humans called Imerslund-Gräsbeck syndrome. The purpose of this study was to determine the molecular cause of this disorder in Komondors. RESULTS Whole genome sequencing of two affected Komondor dogs of unknown relatedness and one parent and a clinically-normal littermate of an affected dog revealed a pathogenic single-base change in the CUBN intron 55 splice donor consensus sequence (NM_001003148.1: c.8746 + 1G > A) that was homozygous in affected dogs and heterozygous in the unaffected parents. Alleles of the variant co-segregated with alleles of the disease locus in the entire family and all more distantly-related sporadic cases. A population study using a simple allele-specific DNA test indicated mutant allele frequencies of 8.3 and 4.5% among North American and Hungarian Komondors, respectively. CONCLUSIONS DNA testing can be used diagnostically in Komondors when clinical signs are suggestive of cobalamin deficiency or to inform Komondor breeders prospectively and prevent occurrence of future affected dogs. This represents the third cubilin variant causing inherited selective cobalamin malabsorption in a large animal ortholog of human Imerslund-Gräsbeck syndrome.
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Affiliation(s)
- John C. Fyfe
- Laboratory of Comparative Medical Genetics, Michigan State University, 567 Wilson Road, East Lansing, MI 48824 USA
- Department of Microbiology & Molecular Genetics, Michigan State University, 567 Wilson Road, East Lansing, MI 48824 USA
| | - Shelby L. Hemker
- Laboratory of Comparative Medical Genetics, Michigan State University, 567 Wilson Road, East Lansing, MI 48824 USA
- Present address: Department of Pediatrics, Division of Nephrology, UPMC Children’s Hospital of Pittsburgh, University of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA 15224 USA
| | - Alycia Frampton
- Section of Medical Genetics, University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA 19104-6010 USA
| | - Karthik Raj
- Section of Medical Genetics, University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA 19104-6010 USA
| | - Peter L. Nagy
- Laboratory of Personalized Genomic Medicine, Department of Pathology & Cell Biology, Columbia University - College of Physicians & Surgeons, 630 West 168th Street, New York, NY 10032 USA
- Present address: MNG Laboratories™, 5424 Glenridge Drive NE, Atlanta, GA 30342 USA
| | - Kristi J. Gibbon
- Oregon Veterinary Referral Associates, 444 B Street, Springfield, OR 97477 USA
- Cottonwood Heights, USA
| | - Urs Giger
- Section of Medical Genetics, University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA 19104-6010 USA
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Structural assembly of the megadalton-sized receptor for intestinal vitamin B 12 uptake and kidney protein reabsorption. Nat Commun 2018; 9:5204. [PMID: 30523278 PMCID: PMC6283879 DOI: 10.1038/s41467-018-07468-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/01/2018] [Indexed: 11/08/2022] Open
Abstract
The endocytic receptor cubam formed by the 460-kDa protein cubilin and the 45-kDa transmembrane protein amnionless (AMN), is essential for intestinal vitamin B12 (B12) uptake and for protein (e.g. albumin) reabsorption from the kidney filtrate. Loss of function of any of the two components ultimately leads to serious B12 deficiency and urinary protein loss in humans (Imerslund-Gräsbeck’s syndrome, IGS). Here, we present the crystal structure of AMN in complex with the amino-terminal region of cubilin, revealing a sophisticated assembly of three cubilin subunits combining into a single intertwined β-helix domain that docks to a corresponding three-faced β-helix domain in AMN. This β-helix-β-helix association thereby anchors three ligand-binding cubilin subunits to the transmembrane AMN. Electron microscopy of full-length cubam reveals a 700–800 Å long tree-like structure with the potential of dimerization into an even larger complex. Furthermore, effects of known human mutations causing IGS are explained by the structural information. Cubilin and the transmembrane protein amnionless (AMN) form the endocytic receptor cubam that is essential for intestinal vitamin B12 uptake. Here the authors present the 2.3 Å crystal structure of AMN in complex with the amino-terminal region of cubilin and discuss cubam architecture and disease causing mutations.
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Kozyraki R, Cases O. Cubilin, the Intrinsic Factor-Vitamin B12 Receptor in Development and Disease. Curr Med Chem 2018; 27:3123-3150. [PMID: 30295181 DOI: 10.2174/0929867325666181008143945] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 08/11/2018] [Accepted: 08/21/2018] [Indexed: 12/29/2022]
Abstract
Gp280/Intrinsic factor-vitamin B12 receptor/Cubilin (CUBN) is a large endocytic receptor serving multiple functions in vitamin B12 homeostasis, renal reabsorption of protein or toxic substances including albumin, vitamin D-binding protein or cadmium. Cubilin is a peripheral membrane protein consisting of 8 Epidermal Growth Factor (EGF)-like repeats and 27 CUB (defined as Complement C1r/C1s, Uegf, BMP1) domains. This structurally unique protein interacts with at least two molecular partners, Amnionless (AMN) and Lrp2/Megalin. AMN is involved in appropriate plasma membrane transport of Cubilin whereas Lrp2 is essential for efficient internalization of Cubilin and its ligands. Observations gleaned from animal models with Cubn deficiency or human diseases demonstrate the importance of this protein. In this review addressed to basic research and medical scientists, we summarize currently available data on Cubilin and its implication in renal and intestinal biology. We also discuss the role of Cubilin as a modulator of Fgf8 signaling during embryonic development and propose that the Cubilin-Fgf8 interaction may be relevant in human pathology, including in cancer progression, heart or neural tube defects. We finally provide experimental elements suggesting that some aspects of Cubilin physiology might be relevant in drug design.
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Affiliation(s)
- Renata Kozyraki
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris-Diderot University, Paris, France
| | - Olivier Cases
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris-Diderot University, Paris, France
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Hosokawa S, Hosokawa K, Ishiyama G, Ishiyama A, Lopez IA. Immunohistochemical localization of megalin and cubilin in the human inner ear. Brain Res 2018; 1701:153-160. [PMID: 30218661 DOI: 10.1016/j.brainres.2018.09.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/09/2018] [Accepted: 09/11/2018] [Indexed: 01/10/2023]
Abstract
Megalin and cubilin are endocytic receptors expressed in many absorptive polarized epithelia. These receptors have been implicated in the transport of gentamicin in the inner ear as possible contributors to ototoxic damage. Megalin and cubilin have been characterized in detail in the mouse and rat inner ear, but not in the human inner ear. In this study, megalin and cubilin were localized by immunohistochemistry using affinity-purified antibodies in formalin fixed frozen cryostat and celloidin embedded sections of the human inner ear. In the cochlea megalin and cubilin were localized in marginal cells of the stria vascularis, epithelial cells of the spiral prominence and the Reissner's membrane. In the macula utricle and cristae ampullaris, megalin and cubilin were localized in transitional and dark cells, but not in vestibular hair cells and supporting cells. In the endolymphatic duct megalin and cubilin were localized in the epithelial cells. The localization of megalin and cubilin in the human inner ear is consistent with previous reports in the inner ear of animal models and suggest that these receptors may play an important role in the inner ear endocytic transport, and maybe potential targets for prevention of ototoxic damage or the delivery of medications.
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Affiliation(s)
- Seiji Hosokawa
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, United States; Department of Otorhinolaryngology/Head & Neck Surgery, Hamamatsu University School of Medicine, Japan
| | - Kumiko Hosokawa
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, United States; Department of Otorhinolaryngology/Head & Neck Surgery, Hamamatsu University School of Medicine, Japan
| | - Gail Ishiyama
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Akira Ishiyama
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Ivan A Lopez
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, United States.
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Schneider M, Al-Shareffi E, Haltiwanger RS. Biological functions of fucose in mammals. Glycobiology 2018; 27:601-618. [PMID: 28430973 DOI: 10.1093/glycob/cwx034] [Citation(s) in RCA: 256] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 04/13/2017] [Indexed: 12/13/2022] Open
Abstract
Fucose is a 6-deoxy hexose in the l-configuration found in a large variety of different organisms. In mammals, fucose is incorporated into N-glycans, O-glycans and glycolipids by 13 fucosyltransferases, all of which utilize the nucleotide-charged form, GDP-fucose, to modify targets. Three of the fucosyltransferases, FUT8, FUT12/POFUT1 and FUT13/POFUT2, are essential for proper development in mice. Fucose modifications have also been implicated in many other biological functions including immunity and cancer. Congenital mutations of a Golgi apparatus localized GDP-fucose transporter causes leukocyte adhesion deficiency type II, which results in severe developmental and immune deficiencies, highlighting the important role fucose plays in these processes. Additionally, changes in levels of fucosylated proteins have proven as useful tools for determining cancer diagnosis and prognosis. Chemically modified fucose analogs can be used to alter many of these fucose dependent processes or as tools to better understand them. In this review, we summarize the known roles of fucose in mammalian physiology and pathophysiology. Additionally, we discuss recent therapeutic advances for cancer and other diseases that are a direct result of our improved understanding of the role that fucose plays in these systems.
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Affiliation(s)
- Michael Schneider
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Esam Al-Shareffi
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.,Department of Psychiatry, Georgetown University Hospital, Washington, DC 20007, USA
| | - Robert S Haltiwanger
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.,Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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Surendran S, Adaikalakoteswari A, Saravanan P, Shatwaan IA, Lovegrove JA, Vimaleswaran KS. An update on vitamin B12-related gene polymorphisms and B12 status. GENES AND NUTRITION 2018; 13:2. [PMID: 29445423 PMCID: PMC5801754 DOI: 10.1186/s12263-018-0591-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/23/2018] [Indexed: 12/12/2022]
Abstract
Background Vitamin B12 is an essential micronutrient in humans needed for health maintenance. Deficiency of vitamin B12 has been linked to dietary, environmental and genetic factors. Evidence for the genetic basis of vitamin B12 status is poorly understood. However, advancements in genomic techniques have increased the knowledge-base of the genetics of vitamin B12 status. Based on the candidate gene and genome-wide association (GWA) studies, associations between genetic loci in several genes involved in vitamin B12 metabolism have been identified. Objective The objective of this literature review was to identify and discuss reports of associations between single-nucleotide polymorphisms (SNPs) in vitamin B12 pathway genes and their influence on the circulating levels of vitamin B12. Methods Relevant articles were obtained through a literature search on PubMed through to May 2017. An article was included if it examined an association of a SNP with serum or plasma vitamin B12 concentration. Beta coefficients and odds ratios were used to describe the strength of an association, and a P < 0.05 was considered as statistically significant. Two reviewers independently evaluated the eligibility for the inclusion criteria and extracted the data. Results From 23 studies which fulfilled the selection criteria, 16 studies identified SNPs that showed statistically significant associations with vitamin B12 concentrations. Fifty-nine vitamin B12-related gene polymorphisms associated with vitamin B12 status were identified in total, from the following populations: African American, Brazilian, Canadian, Chinese, Danish, English, European ancestry, Icelandic, Indian, Italian, Latino, Northern Irish, Portuguese and residents of the USA. Conclusion Overall, the data analyzed suggests that ethnic-specific associations are involved in the genetic determination of vitamin B12 concentrations. However, despite recent success in genetic studies, the majority of identified genes that could explain variation in vitamin B12 concentrations were from Caucasian populations. Further research utilizing larger sample sizes of non-Caucasian populations is necessary in order to better understand these ethnic-specific associations.
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Affiliation(s)
- S Surendran
- 1Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences and Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, PO Box 226, Whiteknights, Reading, RG6 6AP UK
| | - A Adaikalakoteswari
- 2Warwick Medical School - Population Evidence and Technologies, University of Warwick, Coventry, CV4 7AL UK.,3UK Academic Department of Diabetes and Metabolism, George Eliot Hospital, Nuneaton, UK
| | - P Saravanan
- 2Warwick Medical School - Population Evidence and Technologies, University of Warwick, Coventry, CV4 7AL UK.,3UK Academic Department of Diabetes and Metabolism, George Eliot Hospital, Nuneaton, UK
| | - I A Shatwaan
- 1Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences and Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, PO Box 226, Whiteknights, Reading, RG6 6AP UK
| | - J A Lovegrove
- 1Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences and Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, PO Box 226, Whiteknights, Reading, RG6 6AP UK
| | - K S Vimaleswaran
- 1Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences and Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, PO Box 226, Whiteknights, Reading, RG6 6AP UK
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Amnionless-mediated glycosylation is crucial for cell surface targeting of cubilin in renal and intestinal cells. Sci Rep 2018; 8:2351. [PMID: 29402915 PMCID: PMC5799345 DOI: 10.1038/s41598-018-20731-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 01/23/2018] [Indexed: 11/10/2022] Open
Abstract
Mutations in either cubilin (CUBN) or amnionless (AMN) genes cause Imerslund–Gräsbeck syndrome (IGS), a hereditary disease characterised by anaemia attributed to selective intestinal malabsorption of cobalamin and low-molecular weight proteinuria. Although cubilin protein does not have a transmembrane segment, it functions as a multi-ligand receptor by binding to the transmembrane protein, amnionless. We established a system to quantitatively analyse membrane targeting of the protein complex in cultured renal and intestinal cells and analysed the pathogenic mechanisms of mutations found in IGS patients. A novel CUBN mutation, several previously reported CUBN missense mutations and all previously reported AMN missense mutations resulted in endoplasmic reticulum (ER) retention and completely inhibited amnionless-dependent plasma membrane expression of cubilin. The ER retention of cubilin and amnionless was confirmed in renal proximal tubular cells of a patient with IGS. Notably, the interaction between cubilin and amnionless was not sufficient, but amnionless-mediated glycosylation of cubilin was necessary for their surface expression. Quantitative mass spectrometry and mutagenesis demonstrated that N-linked glycosylation of at least 4 residues of cubilin protein was required for its surface targeting. These results delineated the molecular mechanisms of membrane trafficking of cubilin in renal and intestinal cells.
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Pannérec A, Migliavacca E, De Castro A, Michaud J, Karaz S, Goulet L, Rezzi S, Ng TP, Bosco N, Larbi A, Feige JN. Vitamin B12 deficiency and impaired expression of amnionless during aging. J Cachexia Sarcopenia Muscle 2018; 9:41-52. [PMID: 29159972 PMCID: PMC5803611 DOI: 10.1002/jcsm.12260] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 09/01/2017] [Accepted: 10/02/2017] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Physical frailty and loss of mobility in elderly individuals lead to reduced independence, quality of life, and increased mortality. Vitamin B12 deficiency has been linked to several age-related chronic diseases, including in the musculo-skeletal system, where vitamin B12 deficiency is generally believed to be linked to poor nutritional intake. In the present study, we asked whether aging and frailty associate with altered vitamin B12 homeostasis in humans and investigated the underlying molecular mechanisms using preclinical models. METHODS We analysed a subset of the Singapore Longitudinal Aging Study and stratified 238 participants based on age and Fried frailty criteria. Levels of methyl-malonic acid (MMA), a marker for vitamin B12 deficiency, and amnionless, the vitamin B12 co-receptor that anchors the vitamin B12 transport complex to the membrane of epithelial cells, were measured in plasma. In addition, vitamin B12 levels and the molecular mechanisms of vitamin B12 uptake and excretion were analysed in ileum, kidney, liver, and blood using a rat model of natural aging where nutritional intake is fully controlled. RESULTS We demonstrate that aging and frailty are associated with a higher prevalence of functional vitamin B12 deficiency that can be detected by increased levels of MMA in blood (ρ = 0.25; P = 0.00013). The decline in circulating vitamin B12 levels is recapitulated in a rat model of natural aging where food composition and intake are stable. At the molecular level, these perturbations involve altered expression of amnionless in the ileum and kidney. Interestingly, we demonstrate that amnionless can be detected in serum where its levels increase during aging in both rodents and human (P = 3.3e-07 and 9.2e-07, respectively). Blood amnionless levels negatively correlate with vitamin B12 in rats (r2 = 0.305; P = 0.0042) and positively correlate with the vitamin B12 deficiency marker MMA in humans (ρ = 0.22; P = 0.00068). CONCLUSIONS Our results demonstrate that aging and frailty cause intrinsic vitamin B12 deficiencies, which can occur independently of nutritional intake. Mechanistically, vitamin B12 deficiency involves the physio-pathological decline of both the intestinal uptake and the renal reabsorption system for vitamin B12. Finally, amnionless is a novel biomarker which can detect perturbed vitamin B12 bioavailability during aging and physical frailty.
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Affiliation(s)
- Alice Pannérec
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
| | - Eugenia Migliavacca
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
| | | | - Joris Michaud
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
| | - Sonia Karaz
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
| | - Laurence Goulet
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
| | - Serge Rezzi
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
| | - Tze Pin Ng
- Gerontology Research Programme, Department of Psychological Medicine, Young Loo Lin School of Medicine, National University of Singapore, Singapore.,Geriatric Education and Research Institute, Ministry of Health, Singapore
| | | | - Anis Larbi
- Singapore Immunology Network, Biopolis, Agency for Science, Technology and Research, Singapore
| | - Jerome N Feige
- Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, 1015, Lausanne, Switzerland
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Iorember F, Aviles D. Anemia in nephrotic syndrome: approach to evaluation and treatment. Pediatr Nephrol 2017; 32:1323-1330. [PMID: 27999949 DOI: 10.1007/s00467-016-3555-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/22/2016] [Accepted: 11/29/2016] [Indexed: 01/01/2023]
Abstract
Nephrotic syndrome is one of the most common glomerular diseases that affect in children. Complications may occur in nephrotic syndrome as a result of the disease itself as well as its treatment. Most of these complications result from excessive urinary protein losses, and control of proteinuria is the most effective treatment strategy. Anemia is one of the many complications seen in patients with persistent nephrotic syndrome and may occur as a result of excessive urinary losses of iron, transferrin, erythropoietin, transcobalamin and/or metals. This leads to a deficiency of substrates necessary for effective erythropoiesis, requiring supplementation in order to correct the anemia. Supplementation of iron and erythropoietin alone often does not lead to correction of the anemia, suggesting other possible mechanisms which need further investigation. A clear understanding of the pathophysiologic mechanisms of anemia in nephrotic syndrome is necessary to guide appropriate therapy, but only limited evidence is currently available on the precise etiologic mechanisms of anemia in nephrotic syndrome. In this review we focus on the current state of knowledge on the pathogenesis of anemia in nephrotic syndrome.
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Affiliation(s)
- Franca Iorember
- Division of Pediatric Nephrology, Department of Pediatrics, Louisiana State University Health Sciences Center, 200 Henry Clay Avenue, Rm 4241, Now Orleans, LA, 70118, USA
| | - Diego Aviles
- Division of Pediatric Nephrology, Department of Pediatrics, Louisiana State University Health Sciences Center, 200 Henry Clay Avenue, Rm 4241, Now Orleans, LA, 70118, USA.
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Green R, Allen LH, Bjørke-Monsen AL, Brito A, Guéant JL, Miller JW, Molloy AM, Nexo E, Stabler S, Toh BH, Ueland PM, Yajnik C. Vitamin B 12 deficiency. Nat Rev Dis Primers 2017; 3:17040. [PMID: 28660890 DOI: 10.1038/nrdp.2017.40] [Citation(s) in RCA: 465] [Impact Index Per Article: 66.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Vitamin B12 (B12; also known as cobalamin) is a B vitamin that has an important role in cellular metabolism, especially in DNA synthesis, methylation and mitochondrial metabolism. Clinical B12 deficiency with classic haematological and neurological manifestations is relatively uncommon. However, subclinical deficiency affects between 2.5% and 26% of the general population depending on the definition used, although the clinical relevance is unclear. B12 deficiency can affect individuals at all ages, but most particularly elderly individuals. Infants, children, adolescents and women of reproductive age are also at high risk of deficiency in populations where dietary intake of B12-containing animal-derived foods is restricted. Deficiency is caused by either inadequate intake, inadequate bioavailability or malabsorption. Disruption of B12 transport in the blood, or impaired cellular uptake or metabolism causes an intracellular deficiency. Diagnostic biomarkers for B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid. However, the exact cut-offs to classify clinical and subclinical deficiency remain debated. Management depends on B12 supplementation, either via high-dose oral routes or via parenteral administration. This Primer describes the current knowledge surrounding B12 deficiency, and highlights improvements in diagnostic methods as well as shifting concepts about the prevalence, causes and manifestations of B12 deficiency.
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Affiliation(s)
- Ralph Green
- Department of Pathology and Laboratory Medicine, University of California Davis, 4400 V Street, PATH Building, Davis, California 95817, USA
| | - Lindsay H Allen
- USDA, ARS Western Human Nutrition Research Center, University of California Davis, Davis, California, USA
| | | | - Alex Brito
- USDA, ARS Western Human Nutrition Research Center, University of California Davis, Davis, California, USA
| | - Jean-Louis Guéant
- Inserm UMRS 954 N-GERE (Nutrition Génétique et Exposition aux Risques Environnementaux), University of Lorraine and INSERM, Nancy, France
| | - Joshua W Miller
- School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Anne M Molloy
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Ebba Nexo
- Department of Clinical Medicine, Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
| | - Sally Stabler
- Department of Medicine, University of Colorado Denver, Denver, Colorado, USA
| | - Ban-Hock Toh
- Centre for Inflammatory Diseases, Monash Institute of Medical Research, Clayton, Victoria, Australia
| | - Per Magne Ueland
- Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway.,Section for Pharmacology, Department of Clinical Science, University of Bergen, Bergen, Norway
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Endocytic receptor LRP2/megalin—of holoprosencephaly and renal Fanconi syndrome. Pflugers Arch 2017; 469:907-916. [DOI: 10.1007/s00424-017-1992-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 12/31/2022]
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Sun J, Hultenby K, Axelsson J, Nordström J, He B, Wernerson A, Lindström K. Proximal Tubular Expression Patterns of Megalin and Cubilin in Proteinuric Nephropathies. Kidney Int Rep 2017; 2:721-732. [PMID: 29142988 PMCID: PMC5678615 DOI: 10.1016/j.ekir.2017.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 02/09/2017] [Accepted: 02/21/2017] [Indexed: 01/10/2023] Open
Abstract
Introduction Receptor-mediated endocytosis is responsible for protein reabsorption in the proximal tubules. For albumin this process involves at least 2 interacting receptors, megalin and cubilin. Albumin is not usually present in the urine, indicating a highly efficient tubular reuptake under physiological conditions. However, early appearance of albuminuria may mean that the tubular system is overwhelmed by large quantities of albumin or that the function is impaired. Methods To better understand the physiological role of megalin and cubilin in human renal disease, renal biopsies from 15 patients with a range of albuminuria and 3 healthy living donors were analyzed for proximal tubular expression of megalin and cubilin using immunohistochemistry (IHC) and semiquantitative immune-electron microscopy. Their expression in proteinuric zebrafish was also studied. Results Megalin and cubilin were expressed in brush border and cytoplasmic vesicles. Patients with microalbuminuric IgA nephropathy and thin membrane disease had significantly higher megalin in proximal tubules, whereas those with macro- or nephrotic-range albuminuria had unchanged levels. Cubilin expression was significantly higher in all patients. In a proteinuric zebrafish nphs2 knockdown model, we found a dose-dependent increase in the expression of tubular megalin and cubilin in response to tubular protein uptake. Discussion Megalin and cubilin show different expression patterns in different human diseases, which indicates that the 2 tubular proteins differently cooperate in cleaning up plasma proteins in kidney tubules.
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Affiliation(s)
- Jia Sun
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Hultenby
- Division of Clinical Research Center, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Jonas Axelsson
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics; Karolinska Institutet, Stockholm, Sweden.,Department Clinical Immunology, Karolinska University Hospital, Stockholm, Sweden
| | - Johan Nordström
- Division of Transplantation, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Department of Transplant Surgery, Karolinska University Hospital, Stockholm, Sweden
| | - Bing He
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics; Karolinska Institutet, Stockholm, Sweden
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Department of Pathology, Karolinska University Hospital, Stockholm, Sweden
| | - Karin Lindström
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Department of Nephrology, Karolinska University Hospital, Stockholm, Sweden
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50
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Nielsen R, Christensen EI, Birn H. Megalin and cubilin in proximal tubule protein reabsorption: from experimental models to human disease. Kidney Int 2017; 89:58-67. [PMID: 26759048 DOI: 10.1016/j.kint.2015.11.007] [Citation(s) in RCA: 298] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/17/2015] [Accepted: 08/19/2015] [Indexed: 01/19/2023]
Abstract
Proximal tubule protein uptake is mediated by 2 receptors, megalin and cubilin. These receptors rescue a variety of filtered ligands, including biomarkers, essential vitamins, and hormones. Receptor gene knockout animal models have identified important functions of the receptors and have established their essential role in modulating urinary protein excretion. Rare genetic syndromes associated with dysfunction of these receptors have been identified and characterized, providing additional information on the importance of these receptors in humans. Using various disease models in combination with receptor gene knockout, the implications of receptor dysfunction in acute and chronic kidney injury have been explored and have pointed to potential new roles of these receptors. Based on data from animal models, this paper will review current knowledge on proximal tubule endocytic receptor function and regulation, and their role in renal development, protein reabsorption, albumin uptake, and normal renal physiology. These findings have implications for the pathophysiology and diagnosis of proteinuric renal diseases. We will examine the limitations of the different models and compare the findings to phenotypic observations in inherited human disorders associated with receptor dysfunction. Furthermore, evidence from receptor knockout mouse models as well as human observations suggesting a role of protein receptors for renal disease will be discussed in light of conditions such as chronic kidney disease, diabetes, and hypertension.
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Affiliation(s)
- Rikke Nielsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Henrik Birn
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark.
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