1
|
Du R, Zhou C, Chen S, Li T, Lin Y, Xu A, Huang Y, Mei H, Huang X, Tan D, Zheng R, Liang C, Cai Y, Shao Y, Zhang W, Liu L, Zeng C. Atypical phenotypes and novel OCRL variations in southern Chinese patients with Lowe syndrome. Pediatr Nephrol 2024:10.1007/s00467-024-06356-y. [PMID: 38589698 DOI: 10.1007/s00467-024-06356-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 04/10/2024]
Abstract
BACKGROUND Lowe syndrome is characterized by the presence of congenital cataracts, psychomotor retardation, and dysfunctional proximal renal tubules. This study presents a case of an atypical phenotype, investigates the genetic characteristics of eight children diagnosed with Lowe syndrome in southern China, and performs functional analysis of the novel variants. METHODS Whole-exome sequencing was conducted on eight individuals diagnosed with Lowe syndrome from three medical institutions in southern China. Retrospective collection and analysis of clinical and genetic data were performed, and functional analysis was conducted on the five novel variants. RESULTS In our cohort, the clinical symptoms of the eight Lowe syndrome individuals varied. One patient was diagnosed with Lowe syndrome but did not present with congenital cataracts. Common features among all patients included cognitive impairment, short stature, and low molecular weight proteinuria. Eight variations in the OCRL gene were identified, encompassing three previously reported and five novel variations. Among the novel variations, three nonsense mutations were determined to be pathogenic, and two patients harboring novel missense variations of uncertain significance exhibited severe typical phenotypes. Furthermore, all novel variants were associated with altered protein expression levels and impacted primary cilia formation. CONCLUSION This study describes the first case of an atypical Lowe syndrome patient without congenital cataracts in China and performs a functional analysis of novel variants in the OCRL gene, thereby expanding the understanding of the clinical manifestations and genetic diversity associated with Lowe syndrome.
Collapse
Affiliation(s)
- Rong Du
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
- Department of Endocrinology, Genetic, and Rare Diseases, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China
| | - Chengcheng Zhou
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Shehong Chen
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
- Department of Pediatrics, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Tong Li
- Department of Pediatric Endocrinology, The First Affiliated Hospital of Shantou University Medical College, Shantou, 515041, China
| | - Yunting Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Aijing Xu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Yonglan Huang
- Department of Guangzhou Newborn Screening Center, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Huifen Mei
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
- Department of Endocrinology, Genetic, and Rare Diseases, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China
| | - Xiaoli Huang
- Department of Pediatric Neurology, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China
| | - Dongdong Tan
- Department of Endocrinology, Genetic, and Rare Diseases, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China
| | - Ruidan Zheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Cuili Liang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Yanna Cai
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Yongxian Shao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
| | - Wen Zhang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
- Department of Endocrinology, Genetic, and Rare Diseases, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China
- Department of Endocrinology, Genetic, and Rare Diseases, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China
| | - Chunhua Zeng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangdong Provincial Clinical Research Center for Child Health, National Children's Medical Center for South Central Region, Guangzhou Medical University, Guangzhou, 510623, China.
- Department of Endocrinology, Genetic, and Rare Diseases, Guangzhou Women and Children's Medical Center Liuzhou Hospital, Liuzhou, 545000, China.
| |
Collapse
|
2
|
Lolicato F, Nickel W, Haucke V, Ebner M. Phosphoinositide switches in cell physiology - From molecular mechanisms to disease. J Biol Chem 2024; 300:105757. [PMID: 38364889 PMCID: PMC10944118 DOI: 10.1016/j.jbc.2024.105757] [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: 11/28/2023] [Revised: 02/02/2024] [Accepted: 02/08/2024] [Indexed: 02/18/2024] Open
Abstract
Phosphoinositides are amphipathic lipid molecules derived from phosphatidylinositol that represent low abundance components of biological membranes. Rather than serving as mere structural elements of lipid bilayers, they represent molecular switches for a broad range of biological processes, including cell signaling, membrane dynamics and remodeling, and many other functions. Here, we focus on the molecular mechanisms that turn phosphoinositides into molecular switches and how the dysregulation of these processes can lead to disease.
Collapse
Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany; Department of Physics, University of Helsinki, Helsinki, Finland.
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany; Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Ebner
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.
| |
Collapse
|
3
|
Abstract
Phosphoinositides (PIs) are phospholipids derived from phosphatidylinositol. PIs are regulated via reversible phosphorylation, which is directed by the opposing actions of PI kinases and phosphatases. PIs constitute a minor fraction of the total cellular lipid pool but play pleiotropic roles in multiple aspects of cell biology. Genetic mutations of PI regulatory enzymes have been identified in rare congenital developmental syndromes, including ciliopathies, and in numerous human diseases, such as cancer and metabolic and neurological disorders. Accordingly, PI regulatory enzymes have been targeted in the design of potential therapeutic interventions for human diseases. Recent advances place PIs as central regulators of membrane dynamics within functionally distinct subcellular compartments. This brief review focuses on the emerging role PIs play in regulating cell signaling within the primary cilium and in directing transfer of molecules at interorganelle membrane contact sites and identifies new roles for PIs in subcellular spaces.
Collapse
Affiliation(s)
- Elizabeth Michele Davies
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Christina Anne Mitchell
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Harald Alfred Stenmark
- Department of Molecular Cell Biology, Institute for Cancer Research. The Norwegian Radium Hospital, Montebello, N-0379 Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Montebello, N-0379 Oslo, Norway
| |
Collapse
|
4
|
Bura A, de Matteis MA, Bender M, Swinkels M, Versluis J, Jansen AJG, Jurak Begonja A. Oculocerebrorenal syndrome of Lowe protein controls cytoskeletal reorganisation during human platelet spreading. Br J Haematol 2023; 200:87-99. [PMID: 36176266 DOI: 10.1111/bjh.18478] [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: 05/10/2022] [Revised: 09/05/2022] [Accepted: 09/14/2022] [Indexed: 11/28/2022]
Abstract
Lowe syndrome (LS) is a rare, X-linked disorder characterised by numerous symptoms affecting the brain, the eyes, and the kidneys. It is caused by mutations in the oculocerebrorenal syndrome of Lowe (OCRL) protein, a 5-phosphatase localised in different cellular compartments that dephosphorylates phosphatidylinositol-4,5-bisphosphate into phosphatidylinositol-4-monophosphate. Some patients with LS also have bleeding disorders, with normal to low platelet (PLT) count and impaired PLT function. However, the mechanism of PLT dysfunction in patients with LS is not completely understood. The main function of PLTs is to activate upon vessel wall injury and stop the bleeding by clot formation. PLT activation is accompanied by a shape change that is a result of massive cytoskeletal rearrangements. Here, we show that OCRL-inhibited human PLTs do not fully spread, form mostly filopodia, and accumulate actin nodules. These nodules co-localise with ARP2/3 subunit p34, vinculin, and sorting nexin 9. Furthermore, OCRL-inhibited PLTs have a retained microtubular coil with high levels of acetylated tubulin. Also, myosin light chain phosphorylation is decreased upon OCRL inhibition, without impaired degranulation or integrin activation. Taken together, these results suggest that OCRL contributes to cytoskeletal rearrangements during PLT activation that could explain mild bleeding problems in patients with LS.
Collapse
Affiliation(s)
- Ana Bura
- Department of Biotechnology, University of Rijeka, Rijeka, Croatia
| | - Maria Antonietta de Matteis
- Telethon Institute of Genetics and Medicine, TIGEM, Pozzuoli, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
| | - Markus Bender
- Institute of Experimental Biomedicine, University Hospital Wuerzburg, Rudolf Virchow Center, Wuerzburg, Germany
| | - Maurice Swinkels
- Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | - Jurjen Versluis
- Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | | | | |
Collapse
|
5
|
Sena C, Iannello G, Skowronski AA, Dannheim K, Cheung L, Agrawal PB, Hirschhorn JN, Zeitler P, LeDuc CA, Stratigopoulos G, Thaker VV. Endocrine and behavioural features of Lowe syndrome and their potential molecular mechanisms. J Med Genet 2022; 59:1171-1178. [PMID: 35803701 PMCID: PMC10186212 DOI: 10.1136/jmedgenet-2022-108490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 06/11/2022] [Indexed: 01/12/2023]
Abstract
BACKGROUND Lowe syndrome (LS) is an X linked disease caused by pathogenic variants in the OCRL gene that impacts approximately 1 in 500 000 children. Classic features include congenital cataract, cognitive/behavioural impairment and renal tubulopathy. METHODS This study is a retrospective review of clinical features reported by family based survey conducted by Lowe Syndrome Association. Frequency of non-ocular clinical feature(s) of LS and their age of onset was summarised. An LS-specific therapy effectiveness scale was used to assess the response to the administered treatment. Expression of OCRL and relevant neuropeptides was measured in postmortem human brain by qPCR. Gene expression in the mouse brain was determined by reanalysis of publicly available bulk and single cell RNA sequencing. RESULTS A total of 137 individuals (1 female, 89.1% white, median age 14 years (range 0.8-56)) were included in the study. Short stature (height <3rd percentile) was noted in 81% (n=111) individuals, and 15% (n=20) received growth hormone therapy. Undescended testis was reported in 47% (n=64), and median age of onset of puberty was 15 years. Additional features were dental problems (n=77, 56%), bone fractures (n=63, 46%), hypophosphataemia (n=60, 44%), developmental delay and behavioural issues. OCRL is expressed in human and mouse hypothalami, and in hypothalamic cell clusters expressing Ghrh, Sst, Oxt, Pomc and pituitary cells expressing Gh and Prl. CONCLUSIONS There is a wide spectrum of the clinical phenotype of LS. Some of the features may be partly driven by the loss of function of OCRL in the hypothalamus and the pituitary.
Collapse
Affiliation(s)
- Cecilia Sena
- Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Naomi Berrie Diabetes Center, Columbia University Irving Medical Center, New York, New York, USA
| | - Grazia Iannello
- Columbia Stem Cell Initiative, Stem Cell Core, Columbia University Irving Medical Center, New York, New York, USA
| | - Alicja A Skowronski
- Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Naomi Berrie Diabetes Center, Columbia University Irving Medical Center, New York, New York, USA
| | - Katelyn Dannheim
- Department of Pathology and Laboratory Medicine, Rhode Island and Hasbro Children's Hospitals and the Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Leonard Cheung
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Pankaj B Agrawal
- Division of Neonatology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Joel N Hirschhorn
- Division of Endocrinology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Phillip Zeitler
- Department of Endocrinology, Children's Hospital Colorado, Aurora, Colorado, USA
| | - Charles A LeDuc
- Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Naomi Berrie Diabetes Center, Columbia University Irving Medical Center, New York, New York, USA
| | - George Stratigopoulos
- Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Naomi Berrie Diabetes Center, Columbia University Irving Medical Center, New York, New York, USA
| | - Vidhu V Thaker
- Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Naomi Berrie Diabetes Center, Columbia University Irving Medical Center, New York, New York, USA
| |
Collapse
|
6
|
Sandoval L, Fuentealba LM, Marzolo MP. Participation of OCRL1, and APPL1, in the expression, proteolysis, phosphorylation and endosomal trafficking of megalin: Implications for Lowe Syndrome. Front Cell Dev Biol 2022; 10:911664. [PMID: 36340038 PMCID: PMC9630597 DOI: 10.3389/fcell.2022.911664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
Megalin/LRP2 is the primary multiligand receptor for the re-absorption of low molecular weight proteins in the proximal renal tubule. Its function is significantly dependent on its endosomal trafficking. Megalin recycling from endosomal compartments is altered in an X-linked disease called Lowe Syndrome (LS), caused by mutations in the gene encoding for the phosphatidylinositol 5-phosphatase OCRL1. LS patients show increased low-molecular-weight proteins with reduced levels of megalin ectodomain in the urine and accumulation of the receptor in endosomal compartments of the proximal tubule cells. To gain insight into the deregulation of megalin in the LS condition, we silenced OCRL1 in different cell lines to evaluate megalin expression finding that it is post-transcriptionally regulated. As an indication of megalin proteolysis, we detect the ectodomain of the receptor in the culture media. Remarkably, in OCRL1 silenced cells, megalin ectodomain secretion appeared significantly reduced, according to the observation in the urine of LS patients. Besides, the silencing of APPL1, a Rab5 effector associated with OCRL1 in endocytic vesicles, also reduced the presence of megalin’s ectodomain in the culture media. In both silencing conditions, megalin cell surface levels were significantly decreased. Considering that GSK3ß-mediated megalin phosphorylation reduces receptor recycling, we determined that the endosomal distribution of megalin depends on its phosphorylation status and OCRL1 function. As a physiologic regulator of GSK3ß, we focused on insulin signaling that reduces kinase activity. Accordingly, megalin phosphorylation was significantly reduced by insulin in wild-type cells. Moreover, even though in cells with low activity of OCRL1 the insulin response was reduced, the phosphorylation of megalin was significantly decreased and the receptor at the cell surface increased, suggesting a protective role of insulin in a LS cellular model.
Collapse
Affiliation(s)
- Lisette Sandoval
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Luz M. Fuentealba
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - María-Paz Marzolo
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- *Correspondence: María-Paz Marzolo,
| |
Collapse
|
7
|
Wang C, Zhang W, Wang L, Liu W, Guo H. Case Report: Combined Cataract Surgery and Minimally Invasive Glaucoma Surgery Provide an Alternative Treatment Approach for Lowe Syndrome. Front Med (Lausanne) 2022; 9:913229. [PMID: 35847784 PMCID: PMC9283680 DOI: 10.3389/fmed.2022.913229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/15/2022] [Indexed: 11/13/2022] Open
Abstract
We describe the case of a 4-month-old boy who presented with bilateral congenital cataract and high intraocular pressure (IOP) in the left eye, followed by mental retardation and delayed motor development. Genetic investigation revealed the boy had a splicing variant (c.940-11G>A) of the oculocerebrorenal syndrome of Lowe (OCRL) gene. The boy underwent a lensectomy for congenital cataract in his right eye, and lensectomy combined with a 360° suture trabeculotomy to remove the clouded lens and to control IOP of the left eye. During postoperative one-and-a-half-year follow-up, the boy exhibited an improved visual acuity and a well-controlled IOP without the use of topical IOP-lowering medications. Lowe syndrome is a rare multisystemic disorder that is diagnosed through clinical manifestation and genetic testing. The possibility of Lowe syndrome should be considered in patients presenting with typical triad, and genetic analysis should be performed in time to confirm the diagnosis. We recommend combined cataract surgery and minimally invasive glaucoma surgery (MIGS) as a safe, feasible, and efficient method to treat congenital cataract and glaucoma in Lowe syndrome patients.
Collapse
|
8
|
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
|
9
|
Novel pathogenic OCRL mutations and genotype-phenotype analysis of Chinese children affected by oculocerebrorenal syndrome: two cases and a literature review. BMC Med Genomics 2021; 14:219. [PMID: 34488756 PMCID: PMC8422650 DOI: 10.1186/s12920-021-01069-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 08/27/2021] [Indexed: 11/24/2022] Open
Abstract
Background Oculocerebrorenal syndrome of Lowe is a rare X-linked disorder characterized by congenital cataracts, mental retardation, and proximal tubulopathy. This condition is caused by a mutation of OCRL gene (located at chromosome Xq26.1), which encodes an inositol polyphosphate 5-phosphatase. Case presentation We identified two novel OCRL mutations in two unrelated Chinese boys, each with a severe phenotype of Lowe syndrome. A novel de novo deletion (hemizygous c.659_662delAGGG, p.E220Vfs*29) was present in patient 1 and a novel splicing mutation (hemizygous c.2257-2A > T) that was maternally inherited was present in patient 2. A renal biopsy in patient 2 indicated mild mesangial proliferative glomerulonephritis, mild focal mononuclear cells infiltration, and interstitial focal fibrosis. Moreover, renal expression of OCRL-1 protein in patient 2 was significantly reduced compared to a control patient with thin basement membrane disease. Conclusions This study reports two novel OCRL variants associated with severe ocular and neurologic deficiency, despite only mild renal dysfunction. Based on our two patients and a literature review, the genotype–phenotype correlation of OCRL mutations with this severe phenotype of Lowe syndrome suggest a possible clustering of missense, deletion, and nonsense mutations in the 5-phosphatase domain and Rho-GAP domain in the Chinese population.
Collapse
|
10
|
Cannata G, Caporilli C, Grassi F, Perrone S, Esposito S. Management of Congenital Diaphragmatic Hernia (CDH): Role of Molecular Genetics. Int J Mol Sci 2021; 22:ijms22126353. [PMID: 34198563 PMCID: PMC8231903 DOI: 10.3390/ijms22126353] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/04/2021] [Accepted: 06/11/2021] [Indexed: 12/11/2022] Open
Abstract
Congenital diaphragmatic hernia (CDH) is a relatively common major life-threatening birth defect that results in significant mortality and morbidity depending primarily on lung hypoplasia, persistent pulmonary hypertension, and cardiac dysfunction. Despite its clinical relevance, CDH multifactorial etiology is still not completely understood. We reviewed current knowledge on normal diaphragm development and summarized genetic mutations and related pathways as well as cellular mechanisms involved in CDH. Our literature analysis showed that the discovery of harmful de novo variants in the fetus could constitute an important tool for the medical team during pregnancy, counselling, and childbirth. A better insight into the mechanisms regulating diaphragm development and genetic causes leading to CDH appeared essential to the development of new therapeutic strategies and evidence-based genetic counselling to parents. Integrated sequencing, development, and bioinformatics strategies could direct future functional studies on CDH; could be applied to cohorts and consortia for CDH and other birth defects; and could pave the way for potential therapies by providing molecular targets for drug discovery.
Collapse
Affiliation(s)
- Giulia Cannata
- Pediatric Clinic, Pietro Barilla Children’s Hospital, University of Parma, Via Gramsci 14, 43126 Parma, Italy; (G.C.); (C.C.); (F.G.)
| | - Chiara Caporilli
- Pediatric Clinic, Pietro Barilla Children’s Hospital, University of Parma, Via Gramsci 14, 43126 Parma, Italy; (G.C.); (C.C.); (F.G.)
| | - Federica Grassi
- Pediatric Clinic, Pietro Barilla Children’s Hospital, University of Parma, Via Gramsci 14, 43126 Parma, Italy; (G.C.); (C.C.); (F.G.)
| | - Serafina Perrone
- Neonatology Unit, Pietro Barilla Children’s Hospital, Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy;
| | - Susanna Esposito
- Pediatric Clinic, Pietro Barilla Children’s Hospital, University of Parma, Via Gramsci 14, 43126 Parma, Italy; (G.C.); (C.C.); (F.G.)
- Correspondence: ; Tel.: +39-0521-7047
| |
Collapse
|
11
|
A 3D Renal Proximal Tubule on Chip Model Phenocopies Lowe Syndrome and Dent II Disease Tubulopathy. Int J Mol Sci 2021; 22:ijms22105361. [PMID: 34069732 PMCID: PMC8161077 DOI: 10.3390/ijms22105361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 12/28/2022] Open
Abstract
Lowe syndrome and Dent II disease are X-linked monogenetic diseases characterised by a renal reabsorption defect in the proximal tubules and caused by mutations in the OCRL gene, which codes for an inositol-5-phosphatase. The life expectancy of patients suffering from Lowe syndrome is largely reduced because of the development of chronic kidney disease and related complications. There is a need for physiological human in vitro models for Lowe syndrome/Dent II disease to study the underpinning disease mechanisms and to identify and characterise potential drugs and drug targets. Here, we describe a proximal tubule organ on chip model combining a 3D tubule architecture with fluid flow shear stress that phenocopies hallmarks of Lowe syndrome/Dent II disease. We demonstrate the high suitability of our in vitro model for drug target validation. Furthermore, using this model, we demonstrate that proximal tubule cells lacking OCRL expression upregulate markers typical for epithelial–mesenchymal transition (EMT), including the transcription factor SNAI2/Slug, and show increased collagen expression and deposition, which potentially contributes to interstitial fibrosis and disease progression as observed in Lowe syndrome and Dent II disease.
Collapse
|
12
|
Kowal TJ, Prosseda PP, Ning K, Wang B, Alvarado J, Sendayen BE, Jabbehdari S, Stamer WD, Hu Y, Sun Y. Optogenetic Modulation of Intraocular Pressure in a Glucocorticoid-Induced Ocular Hypertension Mouse Model. Transl Vis Sci Technol 2021; 10:10. [PMID: 34111256 PMCID: PMC8107493 DOI: 10.1167/tvst.10.6.10] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/22/2021] [Indexed: 01/03/2023] Open
Abstract
Purpose Steroid-induced glaucoma is a common form of secondary open angle glaucoma characterized by ocular hypertension (elevated intraocular pressure [IOP]) in response to prolonged glucocorticoid exposure. Elevated IOP occurs with increased outflow resistance and altered trabecular meshwork (TM) function. Recently, we used an optogenetic approach in TM to regulate the 5-phosphatase, OCRL, which contributes to regulating PI(4,5)P2 levels. Here, we applied this system with the aim of reversing compromised outflow function in a steroid-induced ocular hypertension mouse model. Methods Elevated IOP was induced by chronic subconjunctival dexamethasone injections in wild-type C57Bl/6j mice. AAV2 viruses containing optogenetic modules of cryptochrome 2 (Cry2)-OCRL-5ptase and CIBN-GFP were injected into the anterior chamber. Four weeks after viral expression and dexamethasone exposure, IOP was measured by tonometer and outflow facility was measured by perfusion apparatus. Human TM cells were treated with dexamethasone, stimulated by light and treated with rhodamine-phalloidin to analyze actin structure. Results Dexamethasone treatment elevated IOP and decreased outflow facility in wild-type mice. Optogenetic constructs were expressed in the TM of mouse eyes. Light stimulation caused CRY2-OCRL-5ptase to translocate to plasma membrane (CIBN-CAAX-GFP) and cilia (CIBN-SSTR3-GFP) in TM cells, which rescued the IOP and outflow facility. In addition, aberrant actin structures formed by dexamethasone treatment were reduced by optogenetic stimulation in human TM cells in culture. Conclusions Subcellular targeting of inositol phosphatases to remove PIP2 represents a promising strategy to reverse defective TM function in steroid-induced ocular hypertension. Translational Relevance Targeted modulation of OCRL may be used to decrease steroid-induced elevated IOP.
Collapse
Affiliation(s)
- Tia J. Kowal
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Philipp P. Prosseda
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Ke Ning
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Biao Wang
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Jorge Alvarado
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Brent E. Sendayen
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Sayena Jabbehdari
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - W. Daniel Stamer
- Duke Eye Center, Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Yang Hu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
- Palo Alto Veterans Administration, Palo Alto, CA, USA
| |
Collapse
|
13
|
Jin YY, Huang LM, Quan XF, Mao JH. Dent disease: classification, heterogeneity and diagnosis. World J Pediatr 2021; 17:52-57. [PMID: 32248351 DOI: 10.1007/s12519-020-00357-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 03/05/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND Dent disease is a rare tubulopathy characterized by manifestations of proximal tubular dysfunction, which occurs almost exclusively in males. It mainly presents symptoms in early childhood and may progress to end-stage renal failure between the 3rd and 5th decades of human life. According to its various genetic basis and to clinical signs and symptoms, researchers define two forms of Dent disease (Dent diseases 1 and 2) and suggest that these forms are produced by mutations in the CLCN5 and OCRL genes, respectively. Dent diseases 1 and 2 account for 60% and 15% of all Dent disease cases, and their genetic cause is generally understood. However, the genetic cause of the remaining 25% of Dent disease cases remains unidentified. DATA SOURCES All relevant peer-reviewed original articles published thus far have been screened out from PubMed and have been referenced. RESULTS Genetic testing has been used greatly to identify mutation types of CLCN5 and OCRL gene, and next-generation sequencing also has been used to identify an increasing number of unknown genotypes. Gene therapy may bring new hope to the treatment of Dent disease. The abuse of hormones and immunosuppressive agents for the treatment of Dent disease should be avoided to prevent unnecessary harm to children. CONCLUSIONS The current research progress in classification, genetic heterogeneity, diagnosis, and treatment of Dent disease reviewed in this paper enables doctors and researchers to better understand Dent disease and provides a basis for improved prevention and treatment.
Collapse
Affiliation(s)
- Yan-Yan Jin
- Department of Nephrology, National Clinical Research Center for Child Health, The Children's Hospital, Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310006, China
| | - Li-Min Huang
- Department of Nephrology, National Clinical Research Center for Child Health, The Children's Hospital, Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310006, China
| | - Xiao-Fang Quan
- Chigene (Beijing) Translational Medical Research Center Co. Ltd, E2 Biomedical Park, No. 88 Kechuang Sixth Ave, Yizhuang, Beijing, China
| | - Jian-Hua Mao
- Department of Nephrology, National Clinical Research Center for Child Health, The Children's Hospital, Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310006, China.
| |
Collapse
|
14
|
Ramadesikan S, Skiba L, Lee J, Madhivanan K, Sarkar D, De La Fuente A, Hanna CB, Terashi G, Hazbun T, Kihara D, Aguilar RC. Genotype & phenotype in Lowe Syndrome: specific OCRL1 patient mutations differentially impact cellular phenotypes. Hum Mol Genet 2021; 30:198-212. [PMID: 33517444 DOI: 10.1093/hmg/ddab025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/15/2020] [Accepted: 01/08/2021] [Indexed: 12/26/2022] Open
Abstract
Lowe Syndrome (LS) is a lethal genetic disorder caused by mutations in the OCRL1 gene which encodes the lipid 5' phosphatase Ocrl1. Patients exhibit a characteristic triad of symptoms including eye, brain and kidney abnormalities with renal failure as the most common cause of premature death. Over 200 OCRL1 mutations have been identified in LS, but their specific impact on cellular processes is unknown. Despite observations of heterogeneity in patient symptom severity, there is little understanding of the correlation between genotype and its impact on phenotype. Here, we show that different mutations had diverse effects on protein localization and on triggering LS cellular phenotypes. In addition, some mutations affecting specific domains imparted unique characteristics to the resulting mutated protein. We also propose that certain mutations conformationally affect the 5'-phosphatase domain of the protein, resulting in loss of enzymatic activity and causing common and specific phenotypes (a conformational disease scenario). This study is the first to show the differential effect of patient 5'-phosphatase mutations on cellular phenotypes and introduces a conformational disease component in LS. This work provides a framework that explains symptom heterogeneity and can help stratify patients as well as to produce a more accurate prognosis depending on the nature and location of the mutation within the OCRL1 gene.
Collapse
Affiliation(s)
- Swetha Ramadesikan
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lisette Skiba
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Jennifer Lee
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | | - Daipayan Sarkar
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | | - Claudia B Hanna
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Genki Terashi
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Tony Hazbun
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Daisuke Kihara
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.,Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA
| | - R Claudio Aguilar
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
15
|
Lemaire M. Novel Fanconi renotubular syndromes provide insights in proximal tubule pathophysiology. Am J Physiol Renal Physiol 2020; 320:F145-F160. [PMID: 33283647 DOI: 10.1152/ajprenal.00214.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The various forms of Fanconi renotubular syndromes (FRTS) offer significant challenges for clinicians and present unique opportunities for scientists who study proximal tubule physiology. This review will describe the clinical characteristics, genetic underpinnings, and underlying pathophysiology of the major forms of FRST. Although the classic forms of FRTS will be presented (e.g., Dent disease or Lowe syndrome), particular attention will be paid to five of the most recently discovered FRTS subtypes caused by mutations in the genes encoding for L-arginine:glycine amidinotransferase (GATM), solute carrier family 34 (type Ii sodium/phosphate cotransporter), member 1 (SLC34A1), enoyl-CoAhydratase/3-hydroxyacyl CoA dehydrogenase (EHHADH), hepatocyte nuclear factor 4A (HNF4A), or NADH dehydrogenase complex I, assembly factor 6 (NDUFAF6). We will explore how mutations in these genes revealed unexpected mechanisms that led to compromised proximal tubule functions. We will also describe the inherent challenges associated with gene discovery studies based on findings derived from small, single-family studies by focusing the story of FRTS type 2 (SLC34A1). Finally, we will explain how extensive alternative splicing of HNF4A has resulted in confusion with mutation nomenclature for FRTS type 4.
Collapse
Affiliation(s)
- Mathieu Lemaire
- Division of Nephrology and Cell Biology Program, SickKids Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Pediatrics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
16
|
Gianesello L, Del Prete D, Anglani F, Calò LA. Genetics and phenotypic heterogeneity of Dent disease: the dark side of the moon. Hum Genet 2020; 140:401-421. [PMID: 32860533 PMCID: PMC7889681 DOI: 10.1007/s00439-020-02219-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/20/2020] [Indexed: 12/18/2022]
Abstract
Dent disease is a rare genetic proximal tubulopathy which is under-recognized. Its phenotypic heterogeneity has led to several different classifications of the same disorder, but it is now widely accepted that the triad of symptoms low-molecular-weight proteinuria, hypercalciuria and nephrocalcinosis/nephrolithiasis are pathognomonic of Dent disease. Although mutations on the CLCN5 and OCRL genes are known to cause Dent disease, no such mutations are found in about 25–35% of cases, making diagnosis more challenging. This review outlines current knowledge regarding Dent disease from another perspective. Starting from the history of Dent disease, and reviewing the clinical details of patients with and without a genetic characterization, we discuss the phenotypic and genetic heterogeneity that typifies this disease. We focus particularly on all those confounding clinical signs and symptoms that can lead to a misdiagnosis. We also try to shed light on a concealed aspect of Dent disease. Although it is a proximal tubulopathy, its misdiagnosis may lead to patients undergoing kidney biopsy. In fact, some individuals with Dent disease have high-grade proteinuria, with or without hematuria, as in the clinical setting of glomerulopathy, or chronic kidney disease of uncertain origin. Although glomerular damage is frequently documented in Dent disease patients’ biopsies, there is currently no reliable evidence of renal biopsy being of either diagnostic or prognostic value. We review published histopathology reports of tubular and glomerular damage in these patients, and discuss current knowledge regarding the role of CLCN5 and OCRL genes in glomerular function.
Collapse
Affiliation(s)
- Lisa Gianesello
- Nephrology, Dialysis and Transplantation Unit, Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani n° 2, 35128, Padua, Italy
| | - Dorella Del Prete
- Nephrology, Dialysis and Transplantation Unit, Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani n° 2, 35128, Padua, Italy
| | - Franca Anglani
- Nephrology, Dialysis and Transplantation Unit, Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani n° 2, 35128, Padua, Italy.
| | - Lorenzo A Calò
- Nephrology, Dialysis and Transplantation Unit, Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani n° 2, 35128, Padua, Italy
| |
Collapse
|
17
|
Onset mechanism of a female patient with Dent disease 2. Clin Exp Nephrol 2020; 24:946-954. [PMID: 32666344 DOI: 10.1007/s10157-020-01926-4] [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: 04/23/2020] [Accepted: 06/23/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Approximately 15% of patients with Dent disease have pathogenic variants in the OCRL gene on Xq25-26, a condition that is referred to as Dent disease 2 (Dent-2). Dent-2 patients sometimes show mild extrarenal features of Lowe syndrome, such as mild mental retardation, suggesting that Dent-2 represents a mild form of Lowe syndrome. To date, eight female patients with Lowe syndrome have been reported, but no female Dent-2 patients have been reported. METHODS In this study, we performed genetic testing of the first female Dent-2 patient to detect the presence of an OCRL variant. Aberrant splicing was demonstrated by in vivo, in vitro, and in silico assays, and skewed X-chromosome inactivation (XCI) in our patient and asymptomatic mothers of three Lowe patients with the heterozygous OCRL variant was evaluated by HUMARA assays using genomic DNA and RNA expression analysis. RESULTS Our patient had an OCRL heterozygous intronic variant of c.1603-3G > C in intron 15 that led to a 169-bp insertion in exon 16, yielding the truncating mutation r.1602_1603ins (169) (p.Val535Glyfs*6) in exon 16. HUMARA assays of leukocytes obtained from this patient demonstrated incompletely skewed XCI (not extremely skewed). On the other hand, the asymptomatic mothers of 3 Lowe patients demonstrated random XCI. These results may lead to our patient's Dent-2 phenotype. CONCLUSIONS This is the first report of a female patient clinically and genetically diagnosed with Dent-2 caused by an OCRL heterozygous splicing site variant and skewed XCI. Skewed XCI may be one of the factors associated with phenotypic diversity in female patients with Lowe syndrome and Dent-2.
Collapse
|
18
|
Abstract
Kidney stone disease (nephrolithiasis) is a common problem that can be associated with alterations in urinary solute composition including hypercalciuria. Studies suggest that the prevalence of monogenic kidney stone disorders, including renal tubular acidosis with deafness, Bartter syndrome, primary hyperoxaluria and cystinuria, in patients attending kidney stone clinics is ∼15%. However, for the majority of individuals, nephrolithiasis has a multifactorial aetiology involving genetic and environmental factors. Nonetheless, the genetic influence on stone formation in these idiopathic stone formers remains considerable and twin studies estimate a heritability of >45% for nephrolithiasis and >50% for hypercalciuria. The contribution of polygenic influences from multiple loci have been investigated by genome-wide association and candidate gene studies, which indicate that a number of genes and molecular pathways contribute to the risk of stone formation. Genetic approaches, studying both monogenic and polygenic factors in nephrolithiasis, have revealed that the following have important roles in the aetiology of kidney stones: transporters and channels; ions, protons and amino acids; the calcium-sensing receptor (a G protein-coupled receptor) signalling pathway; and the metabolic pathways for vitamin D, oxalate, cysteine, purines and uric acid. These advances, which have increased our understanding of the pathogenesis of nephrolithiasis, will hopefully facilitate the future development of targeted therapies for precision medicine approaches in patients with nephrolithiasis.
Collapse
Affiliation(s)
- Sarah A Howles
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.,Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
| |
Collapse
|
19
|
Ma X, Ning K, Jabbehdari S, Prosseda PP, Hu Y, Shue A, Lambert SR, Sun Y. Oculocerebrorenal syndrome of Lowe: Survey of ophthalmic presentations and management. Eur J Ophthalmol 2020; 30:966-973. [PMID: 32340490 PMCID: PMC8177091 DOI: 10.1177/1120672120920544] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Lowe syndrome is a rare X-linked disease that is characterized by renal dysfunction, developmental delays, congenital cataracts and glaucoma. Mutations in the oculocerebral renal syndrome of Lowe (OCRL) gene are found in Lowe syndrome patients. Although loss of vision is a major concern for families and physicians who take care of Lowe syndrome children, definitive cause of visual loss is still unclear. Children usually present with bilateral dense cataracts at birth and glaucoma, which occurs in more than half of cases, either concurrently or following cataract surgery. MATERIALS AND METHODS A retrospective review was conducted on the prevalence and characteristics of ocular findings among families of patients with Lowe syndrome with 137 uniquely affected individuals. RESULTS Of 137 patients, all had bilateral congenital cataracts. Nystagmus was reported in 69.3% of cases, glaucoma in 54.7%, strabismus in 35.0%, and corneal scar in 18.2% of patients. Glaucoma was reported as the most common cause of blindness (46%) followed by corneal scars (41%). Glaucoma occurred in 54.7% of patients and affected both eyes in the majority of cases. Of these patients, 55% underwent surgery for glaucoma, while the remaining patients used medications to control their eye pressure. Timolol and latanoprost were the most commonly used medications. Although trabeculectomy and goniotomy are commonly used for pressure management, aqueous tube shunts had the best outcomes. CONCLUSION Ocular manifestations in individuals with Lowe syndrome and carriers with OCRL mutation are reported which may help familiarize clinicians with the ocular manifestations and management of a rare and complex syndrome.
Collapse
Affiliation(s)
- Xiaowan Ma
- Xiamen Changgung Hospital, Xiamen, China
| | - Ke Ning
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, USA
| | - Sayena Jabbehdari
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Philipp P Prosseda
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, USA
| | - Yang Hu
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, USA
| | - Ann Shue
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, USA
| | - Scott R Lambert
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, USA
| | - Yang Sun
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, USA.,Palo Alto Veterans Administration, Palo Alto, CA, USA
| |
Collapse
|
20
|
Preston R, Naylor RW, Stewart G, Bierzynska A, Saleem MA, Lowe M, Lennon R. A role for OCRL in glomerular function and disease. Pediatr Nephrol 2020; 35:641-648. [PMID: 31811534 PMCID: PMC7056711 DOI: 10.1007/s00467-019-04317-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 07/15/2019] [Accepted: 07/23/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Lowe syndrome and Dent-2 disease are caused by mutations in the OCRL gene, which encodes for an inositol 5-phosphatase. The renal phenotype associated with OCRL mutations typically comprises a selective proximal tubulopathy, which can manifest as Fanconi syndrome in the most extreme cases. METHODS Here, we report a 12-year-old male with nephrotic-range proteinuria and focal segmental glomerulosclerosis on renal biopsy. As a glomerular pathology was suspected, extensive investigation of tubular function was not performed. RESULTS Surprisingly, whole exome sequencing identified a genetic variant in OCRL (c1467-2A>G) that introduced a novel splice mutation leading to skipping of exon 15. In situ hybridisation of adult human kidney tissue and zebrafish larvae showed OCRL expression in the glomerulus, supporting a role for OCRL in glomerular function. In cultured podocytes, we found that OCRL associated with the linker protein IPIP27A and CD2AP, a protein that is important for maintenance of the podocyte slit diaphragm. CONCLUSION Taken together, this work suggests a previously under-appreciated role for OCRL in glomerular function and highlights the importance of investigating tubular function in patients with persistent proteinuria.
Collapse
Affiliation(s)
- Rebecca Preston
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Richard W Naylor
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Graham Stewart
- Renal Department, Ninewells Hospital, Dundee, DD1 9SY, UK
| | | | - Moin A Saleem
- Children's and Academic Renal Unit, University of Bristol, Bristol, UK
| | - Martin Lowe
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK.
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK.
- Department of Paediatric Nephrology, Royal Manchester Children's Hospital, Manchester Academic Health Science Centre, Manchester University Hospital NHS Foundation Trust, Manchester, UK.
| |
Collapse
|
21
|
Complete oculocerebrorenal phenotype of Lowe syndrome in a female patient with half reduction of inositol polyphosphate 5-phosphatase. CEN Case Rep 2019; 9:95-100. [PMID: 31707643 DOI: 10.1007/s13730-019-00434-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 10/29/2019] [Indexed: 10/25/2022] Open
Abstract
The oculocerebrorenal disorder of Lowe syndrome is an X-linked mutation in the gene oculocerebrorenal syndrome of Lowe 1 (OCRL), characterized by the triad of congenital cataracts, severe intellectual impairment, and renal tubular dysfunction. Manifestations of phenotype in female carriers and patients are extremely rare. We present a female case with congenital cataracts, severe intellectual impairment, sensorineural hearing loss, and renal tubular dysfunction as Lowe syndrome. A 9-year-old Japanese girl visited our hospital due to prolonged proteinuria. Her renal biopsy revealed diffuse mesangium proliferation, sclerosis and dilatation of renal tubules, and mild IgA deposition in the mesangial region. Furthermore, she had congenital cataracts, severe intellectual impairment, and sensorineural hearing loss. Genetic screening did not identify mutations of the ORCL gene encoding inositol polyphosphate 5-phosphatase (IPP-5P) (46 XX, female). However, we found the reduction of enzyme activity of IPP-5P to 50% of the normal value. Furthermore, her renal function had deteriorated to renal failure within a decade. Finally, she received peritoneal dialysis and renal transplantation. We present the oculocerebrorenal phenotype of Lowe syndrome in a female patient with reduced activity of IPP-5P without OCRL gene mutation.
Collapse
|
22
|
Lowe syndrome identified in the offspring of an oocyte donor who was an unknown carrier of a de novo mutation: a case report and review of the literature. J Med Case Rep 2019; 13:325. [PMID: 31676009 PMCID: PMC6825338 DOI: 10.1186/s13256-019-2263-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/22/2019] [Indexed: 11/30/2022] Open
Abstract
Background Oculocerebrorenal syndrome of Lowe is an X-linked disorder with very low prevalence in the general population. The OCRL gene encodes the protein phosphatidylinositol 4,5-bisphosphate-5-phosphatase, a lipid phosphatase, located in the trans-Golgi network. Point mutations in the OCRL gene cause Lowe syndrome and Dent disease, which are characterized as a multisystemic disorder. The symptoms of Lowe syndrome are expressed primarily as dysfunction of the eyes, kidneys, and the central nervous system. Case presentation This report describes a case of a 31-year-old Georgian woman with a de novo pathogenic mutation causing oculocerebrorenal syndrome of Lowe, who was a volunteer in an oocyte donation program for in vitro fertilization purposes, and the outcome of the treatments of this particular donor’s oocyte receivers, describing the implications of the mutation for the children born as a result of the treatments. It raises important medical and ethical issues about the necessity of genetic testing of oocyte donors and the possibility of rare genetic disorders being inherited by the offspring of donors. Conclusion This particular case indicates the legal, medical, and emotional risks of utilizing donor oocytes from phenotypically healthy women, whose genetic constitution is unknown in terms of being silent carriers of rare diseases. In addition, all the necessary actions were followed; the further examinations that are required are mentioned. The donor and the offspring should be further tested. The remaining cryopreserved embryos should be destroyed or preimplantation genetic testing should be performed before they are utilized. Finally, all the people involved, the treated couples and the donor, alongside her family, should follow genetic and psychological counselling.
Collapse
|
23
|
Dai C, Wang L, Li Y, Zheng Z, Qian J, Wang C, Liu Z, Shan X. Lowe syndrome with extremely short stature: growth hormone deficiency may be the pathogeny. Growth Factors 2019; 37:170-177. [PMID: 31576764 DOI: 10.1080/08977194.2019.1669589] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Lowe syndrome is an x-linked disorder characterized by congenital cataracts, nervous system abnormalities and renal tubular dysfunction. With the rising number of reported cases, more patients are found to suffer from endocrine abnormalities. Hereby, three Chinese patients with typical symptoms and extremely short stature were described. The OCRL gene was analyzed. A combination of blood biochemistry and radiological examinations were performed. Growth hormone provocation test was taken in one patient. Nucleotide sequence analysis revealed a de novo novel hemizygous mutation (c.2290_2291delinsCT) in exon 21 in an adolescent boy. As indicated by the growth hormone provocation test, the boy had growth hormone deficiency. The other two patients were brothers with extremely short stature, and manifested the same hemizygous mutation (c.2581G > A) in exon 23. It was speculated that the mutation of OCRL gene could lead to deficiency of growth hormone, for which an early growth hormone intervention may be beneficial.
Collapse
Affiliation(s)
- Chengjun Dai
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Liying Wang
- Beijing Tongren Hospital, Capital Medical University, Beijing, PR China
| | - Youli Li
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Zhichao Zheng
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Jieqi Qian
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Chaoban Wang
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Zishuo Liu
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Xiaoou Shan
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| |
Collapse
|
24
|
Zhou FQ, Wang QW, Liu ZZ, Zhang XL, Wang DN, Dongye MM, Lin HT, Chen WR. Novel mutation in OCRL leading to a severe form of Lowe syndrome. Int J Ophthalmol 2019; 12:1057-1060. [PMID: 31341792 DOI: 10.18240/ijo.2019.07.01] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 02/01/2019] [Indexed: 01/02/2023] Open
Abstract
AIM To investigate the phenotype and genotype of a family with X-linked recessive Lowe syndrome. METHODS All the members in the Chinese pedigree underwent comprehensive ophthalmologic and systemic examinations. Genomic DNA was isolated from peripheral blood of the pedigree members and 100 unrelated healthy Chinese subjects. Direct sequencing was performed to screen the exons and intron boundaries of OCRL. RESULTS The ophthalmological and systemic examinations suggested that the affected individual had Lowe syndrome. The phenotype in the pedigree is severe and consistent among all the affected individuals except for an individual who additionally suffered from congenital heart disease and laryngeal cartilage dysplasia. Directional Sanger sequencing identified a complex mutation c.(2368_2368delG; c.2370A>C) in the Rho-GTPase activating protein domain. This complex mutation causes termination of protein synthesis at amino acid 824 and result in a new peptide with 823 amino acids (p.Ala790ProfsX34). This mutation was not detected in 100 unrelated healthy Chinese subjects. CONCLUSION Our findings expand the phenotypic and genotypic spectrum of Lowe syndrome.
Collapse
Affiliation(s)
- Feng-Qi Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China.,New England College of Optometry, Boston, MA 02115, USA
| | - Qi-Wei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| | - Zhen-Zhen Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| | - Xu-Lin Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| | - Dong-Ni Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| | - Mei-Mei Dongye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| | - Hao-Tian Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| | - Wei-Rong Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
| |
Collapse
|
25
|
Staiano L, De Matteis MA. Phosphoinositides in the kidney. J Lipid Res 2018; 60:287-298. [PMID: 30314999 DOI: 10.1194/jlr.r089946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Indexed: 11/20/2022] Open
Abstract
Phosphoinositides (PIs) play pivotal roles in the regulation of many biological processes. The quality and quantity of PIs is regulated in time and space by the activity of PI kinases and PI phosphatases. The number of PI-metabolizing enzymes exceeds the number of PIs with, in many cases, more than one enzyme controlling the same biochemical step. This would suggest that the PI system has an intrinsic ability to buffer and compensate for the absence of a specific enzymatic activity. However, there are several examples of severe inherited human diseases caused by mutations in one of the PI enzymes, although other enzymes with the same activity are fully functional. The kidney depends strictly on PIs for physiological processes, such as cell polarization, filtration, solute reabsorption, and signal transduction. Indeed, alteration of the PI system in the kidney very often results in pathological conditions, both inherited and acquired. Most of the knowledge of the roles that PIs play in the kidney comes from the study of KO animal models for genes encoding PI enzymes and from the study of human genetic diseases, such as Lowe syndrome/Dent disease 2 and Joubert syndrome, caused by mutations in the genes encoding the PI phosphatases, OCRL and INPP5E, respectively.
Collapse
Affiliation(s)
- Leopoldo Staiano
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy .,University of Naples Federico II, 80131 Naples, Italy
| |
Collapse
|
26
|
Abstract
Lowe syndrome is an X-linked disease that is characterized by congenital cataracts, central hypotonia, intellectual disability and renal Fanconi syndrome. The disease is caused by mutations in OCRL, which encodes an inositol polyphosphate 5-phosphatase (OCRL) that acts on phosphoinositides - quantitatively minor constituents of cell membranes that are nonetheless pivotal regulators of intracellular trafficking. In this Review we summarize the considerable progress made over the past decade in understanding the cellular roles of OCRL in regulating phosphoinositide balance along the endolysosomal pathway, a fundamental system for the reabsorption of proteins and solutes by proximal tubular cells. We discuss how studies of OCRL have led to important discoveries about the basic mechanisms of membrane trafficking and describe the key features and limitations of the currently available animal models of Lowe syndrome. Mutations in OCRL can also give rise to a milder pathology, Dent disease 2, which is characterized by renal Fanconi syndrome in the absence of extrarenal pathologies. Understanding how mutations in OCRL give rise to two clinical entities with differing extrarenal manifestations represents an opportunity to identify molecular pathways that could be targeted to develop treatments for these conditions.
Collapse
|
27
|
Inoue K, Balkin DM, Liu L, Nandez R, Wu Y, Tian X, Wang T, Nussbaum R, De Camilli P, Ishibe S. Kidney Tubular Ablation of Ocrl/ Inpp5b Phenocopies Lowe Syndrome Tubulopathy. J Am Soc Nephrol 2016; 28:1399-1407. [PMID: 27895154 DOI: 10.1681/asn.2016080913] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 10/05/2016] [Indexed: 12/26/2022] Open
Abstract
Lowe syndrome and Dent disease are two conditions that result from mutations of the inositol 5-phosphatase oculocerebrorenal syndrome of Lowe (OCRL) and share the feature of impaired kidney proximal tubule function. Genetic ablation of Ocrl in mice failed to recapitulate the human phenotypes, possibly because of the redundant functions of OCRL and its paralog type 2 inositol polyphosphate-5-phosphatase (INPP5B). Germline knockout of both paralogs in mice results in early embryonic lethality. We report that kidney tubule-specific inactivation of Inpp5b on a global Ocrl-knockout mouse background resulted in low molecular weight proteinuria, phosphaturia, and acidemia. At the cellular level, we observed a striking impairment of clathrin-dependent and -independent endocytosis in proximal tubules, phenocopying what has been reported for Dent disease caused by mutations in the gene encoding endosomal proton-chloride exchange transporter 5. These results suggest that the functions of OCRL/INPP5B and proton-chloride exchange transporter 5 converge on shared mechanisms, the impairment of which has a dramatic effect on proximal tubule endocytosis.
Collapse
Affiliation(s)
| | - Daniel M Balkin
- Cell Biology.,Howard Hughes Medical Institute, and.,Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, Connecticut
| | - Lijuan Liu
- Cell Biology.,Howard Hughes Medical Institute, and.,Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, Connecticut.,Neuroscience, and
| | - Ramiro Nandez
- Cell Biology.,Howard Hughes Medical Institute, and.,Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, Connecticut
| | - Yumei Wu
- Cell Biology.,Howard Hughes Medical Institute, and.,Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, Connecticut.,Neuroscience, and
| | | | | | - Robert Nussbaum
- Department of Medicine and.,Institute of Human Genetics, University of California, San Francisco, California; and.,Howard Hughes Medical Institute, and
| | - Pietro De Camilli
- Cell Biology, .,Howard Hughes Medical Institute, and.,Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, Connecticut.,Neuroscience, and
| | - Shuta Ishibe
- Departments of Internal Medicine, .,Cellular and Molecular Physiology
| |
Collapse
|
28
|
Abstract
The oculocerebrorenal syndrome of Lowe is a rare X-linked multisystemic disorder characterized by the triad of congenital cataracts, intellectual disability, and proximal renal tubular dysfunction. Whereas the ocular manifestations and severe muscular hypotonia are the typical first diagnostic clues apparent at birth, the manifestations of incomplete renal Fanconi syndrome are often recognized only later in life. Other characteristic features are progressive severe growth retardation and behavioral problems, with tantrums. Many patients develop a debilitating arthropathy. Treatment is symptomatic, and the life span rarely exceeds 40 years. The causative oculocerebrorenal syndrome of Lowe gene (OCRL) encodes the inositol polyphosphate 5-phosphatase OCRL-1. OCRL variants have not only been found in classic Lowe syndrome, but also in patients with a predominantly renal phenotype classified as Dent disease type 2 (Dent-2). Recent data indicate that there is a phenotypic continuum between Dent-2 disease and Lowe syndrome, suggesting that there are individual differences in the ability to compensate for the loss of enzyme function. Extensive research has demonstrated that OCRL-1 is involved in multiple intracellular processes involving endocytic trafficking and actin skeleton dynamics. This explains the multi-organ manifestations of the disease. Still, the mechanisms underlying the wide phenotypic spectrum are poorly understood, and we are far from a causative therapy. In this review, we provide an update on clinical and molecular genetic findings in Lowe syndrome and the cellular and physiological functions of OCRL-1.
Collapse
|
29
|
Recker F, Zaniew M, Böckenhauer D, Miglietti N, Bökenkamp A, Moczulska A, Rogowska-Kalisz A, Laube G, Said-Conti V, Kasap-Demir B, Niemirska A, Litwin M, Siteń G, Chrzanowska KH, Krajewska-Walasek M, Sethi SK, Tasic V, Anglani F, Addis M, Wasilewska A, Szczepańska M, Pawlaczyk K, Sikora P, Ludwig M. Characterization of 28 novel patients expands the mutational and phenotypic spectrum of Lowe syndrome. Pediatr Nephrol 2015; 30:931-43. [PMID: 25480730 DOI: 10.1007/s00467-014-3013-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 11/07/2014] [Accepted: 11/11/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND The oculocerebrorenal syndrome of Lowe (OCRL) is a rare X-linked multi-systemic disorder, almost always characterized by the triad of congenital cataract, cognitive and behavioral impairment and a proximal tubulopathy. METHODS Twenty-eight novel patients with suspected Lowe syndrome were studied. RESULTS All patients carried OCRL gene defects with mutational hot spots at CpG dinucleotides. Mutations previously unknown in Lowe syndrome were observed in ten of the 28 patients, and carriership was identified in 30.4 % of the mothers investigated. Mapping the exact breakpoints of a complete OCRL gene deletion revealed involvement of several flanking repeat elements. We noted a similar pattern of documented clinically relevant symptoms, and even though the patient cohort comprised relatively young patients, 32 % of these patients already showed advanced chronic kidney disease. Thrombocytopenia was seen in several patients, and hyperosmia and/or hyperacusis were reported recurrently. A p.Asp523Asn mutation in a Polish patient, associated with the typical cerebrorenal spectrum but with late cataract (10 year), was also evident in two milder affected Italian brothers with ocular involvement of similar progression. CONCLUSIONS We have identified clinical features in 28 patients with suspected Lowe syndrome that had not been recognized in Lowe syndrome prior to our study. We also provide further evidence that OCRL mutations cause a phenotypic continuum with selective and/or time-dependent organ involvement. At least some of these mutants might exhibit a genotype-phenotype correlation.
Collapse
Affiliation(s)
- Florian Recker
- Department of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Allmendinger AM, Desai NS, Burke AT, Viswanadhan N, Prabhu S. Neuroimaging and renal ultrasound manifestations of Oculocerebrorenal syndrome of Lowe. J Radiol Case Rep 2014; 8:1-7. [PMID: 25426219 DOI: 10.3941/jrcr.v8i10.1740] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Oculocerebrorenal syndrome of Lowe (OCRL) is a multisystem disorder characterized by congenital cataracts, hypotonia, and cognitive developmental delay with renal complications developing in the first few months of life. Clinical and laboratory findings of Lowe syndrome are well documented. Though a small number of case reports describe the neuroimaging features and the renal ultrasound manifestations of this disease, a comprehensive review of all the imaging manifestations has not been reported. The authors present a case of OCRL and review the neuroimaging and renal ultrasound manifestations of this multisystem disease.
Collapse
Affiliation(s)
| | - Naman S Desai
- Department of Neuroradiology, Brigham and Women's Hospital, Boston, USA
| | | | | | - Sanjay Prabhu
- Department of Neuroradiology, Boston Children's Hospital, Boston, USA
| |
Collapse
|
31
|
Mukherjee D, Sen A, Aguilar RC. RhoGTPase-binding proteins, the exocyst complex and polarized vesicle trafficking. Small GTPases 2014; 5:e28453. [PMID: 24691289 DOI: 10.4161/sgtp.28453] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cell polarity, the asymmetric distribution of proteins and lipids, is essential for a variety of cellular functions. One mechanism orchestrating cell polarity is polarized vesicle trafficking; whereby cargo loaded secretory vesicles are specifically transported to predetermined areas of the cell. The evolutionarily conserved exocyst complex and its small GTPase regulators play crucial roles in spatiotemporal control of polarized vesicle trafficking. In studies on neuronal membrane remodeling and synaptic plasticity, conserved mechanisms of exocyst regulation and cargo recycling during polarized vesicle trafficking are beginning to emerge as well. Recently, our lab demonstrated that RhoGTPase-binding proteins in both yeast (Bem3) and mammals (Ocrl1) are also required for the efficient traffic of secretory vesicles to sites of polarized growth and signaling. Together with our studies, we highlight the evolutionary conservation of the basic elements essential for polarized vesicle traffic across different cellular functions and model systems. In conclusion, we emphasize that studies on RhoGTPase-binding proteins in these processes should be included in the next level of investigation, for a more complete understanding of their hitherto unknown roles in polarized membrane traffic and exocyst regulation.
Collapse
Affiliation(s)
| | - Arpita Sen
- Department of Biological Sciences; Purdue University; West Lafayette, IN USA
| | - R Claudio Aguilar
- Department of Biological Sciences; Purdue University; West Lafayette, IN USA
| |
Collapse
|
32
|
Kim HK, Kim JH, Kim YM, Kim GH, Lee BH, Choi JH, Yoo HW. Lowe syndrome: a single center's experience in Korea. KOREAN JOURNAL OF PEDIATRICS 2014; 57:140-8. [PMID: 24778696 PMCID: PMC4000760 DOI: 10.3345/kjp.2014.57.3.140] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 10/13/2013] [Accepted: 10/16/2013] [Indexed: 01/12/2023]
Abstract
Purpose Lowe syndrome is a rare, X-linked recessive disorder caused by mutations in the OCRL gene. It involves multiple anatomic systems, particularly the eyes, central nervous system, and kidneys, and leads to profound growth failure and global developmental delay. This study evaluated the clinical and genetic characteristics of Korean patients with Lowe syndrome. Methods The clinical findings and results of genetic studies were reviewed for 12 male patients diagnosed with Lowe syndrome at a single medical institution. Results The mean age of the patients at presentation was 2.2 months (range, 0-4 months), although the diagnosis was delayed by a mean of 2.8 years (range, 0-9.7 years). The mean follow-up period was 9.0 years (range, 0.6-16.7 years). Nine mutations in OCRL were identified in 11 patients (92%), with three novel mutations. The main presentation was congenital cataract in both eyes necessitating early cataract removal in the 11 patients with impaired visual acuity. Profound short stature and developmental delay were observed in all patients, and seizures occurred in 50% of the patients. All patients suffered from proximal renal tubular dysfunction, and one patient developed chronic renal failure. Other manifestations included pathologic fracture (50%), cutaneous cysts (42%), and cryptorchidism (42%). However, there was no bleeding tendency, and none of the patients died during the study period. Conclusion This study describes the clinical and genetic characteristics of Korean patients with Lowe syndrome. The observations are helpful for understanding the natural courses of Lowe syndrome and for appropriate genetic counseling.
Collapse
Affiliation(s)
- Hyun-Kyung Kim
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Ja Hye Kim
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Yoo-Mi Kim
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Gu-Hwan Kim
- Medical Genetics Center, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Beom Hee Lee
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea. ; Medical Genetics Center, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Jin-Ho Choi
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Han-Wook Yoo
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea. ; Medical Genetics Center, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| |
Collapse
|
33
|
Haque SK, Ariceta G, Batlle D. Proximal renal tubular acidosis: a not so rare disorder of multiple etiologies. Nephrol Dial Transplant 2013; 27:4273-87. [PMID: 23235953 PMCID: PMC3616759 DOI: 10.1093/ndt/gfs493] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Proximal renal tubular acidosis (RTA) (Type II RTA) is characterized by a defect in the ability to reabsorb HCO3 in the proximal tubule. This is usually manifested as bicarbonate wastage in the urine reflecting that the defect in proximal tubular transport is severe enough that the capacity for bicarbonate reabsorption in the thick ascending limb of Henle's loop and more distal nephron segments is overwhelmed. More subtle defects in proximal bicarbonate transport likely go clinically unrecognized owing to compensatory reabsorption of bicarbonate distally. Inherited proximal RTA is more commonly autosomal recessive and has been associated with mutations in the basolateral sodium-bicarbonate cotransporter (NBCe1). Mutations in this transporter lead to reduced activity and/or trafficking, thus disrupting the normal bicarbonate reabsorption process of the proximal tubules. As an isolated defect for bicarbonate transport, proximal RTA is rare and is more often associated with the Fanconi syndrome characterized by urinary wastage of solutes like phosphate, uric acid, glucose, amino acids, low-molecular-weight proteins as well as bicarbonate. A vast array of rare tubular disorders may cause proximal RTA but most commonly it is induced by drugs. With the exception of carbonic anhydrase inhibitors which cause isolated proximal RTA, drug-induced proximal RTA is associated with Fanconi syndrome. Drugs that have been recently recognized to cause severe proximal RTA with Fanconi syndrome include ifosfamide, valproic acid and various antiretrovirals such as Tenofovir particularly when given to human immunodeficiency virus patients receiving concomitantly protease inhibitors such as ritonavir or reverse transcriptase inhibitors such as didanosine.
Collapse
Affiliation(s)
- Syed K Haque
- Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | | | | |
Collapse
|
34
|
Madhivanan K, Mukherjee D, Aguilar RC. Lowe syndrome: Between primary cilia assembly and Rac1-mediated membrane remodeling. Commun Integr Biol 2013; 5:641-4. [PMID: 23739214 PMCID: PMC3541337 DOI: 10.4161/cib.21952] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Lowe syndrome (LS) is a lethal X-linked genetic disease caused by functional deficiencies of the phosphatidlyinositol 5-phosphatase, Ocrl1. In the past four years, our lab described the first Ocrl1-specific cellular phenotypes using dermal fibroblasts from LS patients. These phenotypes, validated in an ocrl1-morphant zebrafish model, included membrane remodeling (cell migration/spreading, fluid-phase uptake) defects and primary cilia assembly abnormalities. On one hand, our findings unraveled cellular phenotypes likely to be involved in the observed developmental defects; on the other hand, these discoveries established LS as a ciliopathy-associated disease. This article discusses the possible mechanisms by which loss of Ocrl1 function may affect RhoGTPase signaling pathways leading to actin cytoskeleton rearrangements that underlie the observed cellular phenotypes.
Collapse
|
35
|
van Rahden VA, Brand K, Najm J, Heeren J, Pfeffer SR, Braulke T, Kutsche K. The 5-phosphatase OCRL mediates retrograde transport of the mannose 6-phosphate receptor by regulating a Rac1-cofilin signalling module. Hum Mol Genet 2012; 21:5019-38. [PMID: 22907655 DOI: 10.1093/hmg/dds343] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the OCRL gene encoding the phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) 5-phosphatase OCRL cause Lowe syndrome (LS), which is characterized by intellectual disability, cataracts and selective proximal tubulopathy. OCRL localizes membrane-bound compartments and is implicated in intracellular transport. Comprehensive analysis of clathrin-mediated endocytosis in fibroblasts of patients with LS did not reveal any difference in trafficking of epidermal growth factor, low density lipoprotein or transferrin, compared with normal fibroblasts. However, LS fibroblasts displayed reduced mannose 6-phosphate receptor (MPR)-mediated re-uptake of the lysosomal enzyme arylsulfatase B. In addition, endosome-to-trans Golgi network (TGN) transport of MPRs was decreased significantly, leading to higher levels of cell surface MPRs and their enrichment in enlarged, retromer-positive endosomes in OCRL-depleted HeLa cells. In line with the higher steady-state concentration of MPRs in the endosomal compartment in equilibrium with the cell surface, anterograde transport of the lysosomal enzyme, cathepsin D was impaired. Wild-type OCRL counteracted accumulation of MPR in endosomes in an activity-dependent manner, suggesting that PI(4,5)P(2) modulates the activity state of proteins regulated by this phosphoinositide. Indeed, we detected an increased amount of the inactive, phosphorylated form of cofilin and lower levels of the active form of PAK3 upon OCRL depletion. Levels of active Rac1 and RhoA were reduced or enhanced, respectively. Overexpression of Rac1 rescued both enhanced levels of phosphorylated cofilin and MPR accumulation in enlarged endosomes. Our data suggest that PI(4,5)P(2) dephosphorylation through OCRL regulates a Rac1-cofilin signalling cascade implicated in MPR trafficking from endosomes to the TGN.
Collapse
Affiliation(s)
- Vanessa A van Rahden
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | | | | | | | | | | |
Collapse
|
36
|
Peces R, Peces C, de Sousa E, Vega C, Selgas R, Nevado J. A novel and de novo deletion in the OCRL1 gene associated with a severe form of Lowe syndrome. Int Urol Nephrol 2012; 45:1767-71. [PMID: 22821049 DOI: 10.1007/s11255-012-0246-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Accepted: 06/25/2012] [Indexed: 11/30/2022]
Abstract
The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder. The mutation of the gene OCRL1 localized at Xq26.1, coding for the enzyme phosphatidylinositol (4,5) bisphosphate (PIP2P) 5-phosphatase, is responsible for the phenotypic characteristics of the disease. We report a 22-year-old male with a severe form of OCRL syndrome, diagnosed on the basis of congenital cataracts, severe psychomotor and cognitive deficits, and renal tubular dysfunction without Fanconi syndrome. The patient presented low molecular weight proteinuria, nephrocalcinosis, nephrolithiasis, rickets, and growth retardation and developed progressive renal failure. Genetic analysis showed a novel and de novo deletion of exons 10-13 in the OCRL1 gene.
Collapse
Affiliation(s)
- Ramón Peces
- Servicio de Nefrología, Hospital Universitario La Paz. IdiPAZ, Paseo de la Castellana 261, 28046, Madrid, Spain,
| | | | | | | | | | | |
Collapse
|
37
|
Wu G, Zhang W, Na T, Jing H, Wu H, Peng JB. Suppression of intestinal calcium entry channel TRPV6 by OCRL, a lipid phosphatase associated with Lowe syndrome and Dent disease. Am J Physiol Cell Physiol 2012; 302:C1479-91. [PMID: 22378746 DOI: 10.1152/ajpcell.00277.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Oculocerebrorenal syndrome of Lowe (OCRL) gene product is a phosphatidyl inositol 4,5-bisphosphate [PI(4,5)P(2)] 5-phosphatase, and mutations of OCRL cause Lowe syndrome and Dent disease, both of which are frequently associated with hypercalciuria. Transient receptor potential, vanilloid subfamily, subtype 6 (TRPV6) is an intestinal epithelial Ca(2+) channel mediating active Ca(2+) absorption. Hyperabsorption of Ca(2+) was found in patients of Dent disease with increased Ca(2+) excretion. In this study, we tested whether TRPV6 is regulated by OCRL and, if so, to what extent it is altered by Dent-causing OCRL mutations using Xenopus laevis oocyte expression system. Exogenous OCRL decreased TRPV6-mediated Ca(2+) uptake by regulating the function and trafficking of TRPV6 through different domains of OCRL. The PI(4,5)P(2) 5-phosphatase domain suppressed the TRPV6-mediated Ca(2+) transport likely through regulating the PI(4,5)P(2) level needed for TRPV6 function without affecting TRPV6 protein abundance of TRPV6 at the cell surface. The forward trafficking of TRPV6 was decreased by OCRL. The Rab binding domain in OCRL was involved in regulating the trafficking of TRPV6. Knocking down endogenous X. laevis OCRL by antisense approach increased TRPV6-mediated Ca(2+) transport and TRPV6 forward trafficking. All seven Dent-causing OCRL mutations examined exhibited alleviation of the inhibitory effect on TRPV6-mediated Ca(2+) transport together with decreased overall PI(4,5)P(2) 5-phosphatase activity. In conclusion, OCRL suppresses TRPV6 via two separate mechanisms. The disruption of PI(4,5)P(2) 5-phosphatase activity by Dent-causing mutations of OCRL may lead to increased intestinal Ca(2+) absorption and, in turn, hypercalciuria.
Collapse
Affiliation(s)
- Guojin Wu
- Nephrology Research and Training Center, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294-0006, USA
| | | | | | | | | | | |
Collapse
|
38
|
Ramirez IBR, Pietka G, Jones DR, Divecha N, Alia A, Baraban SC, Hurlstone AFL, Lowe M. Impaired neural development in a zebrafish model for Lowe syndrome. Hum Mol Genet 2011; 21:1744-59. [PMID: 22210625 PMCID: PMC3313792 DOI: 10.1093/hmg/ddr608] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Lowe syndrome, which is characterized by defects in the central nervous system, eyes and kidneys, is caused by mutation of the phosphoinositide 5-phosphatase OCRL1. The mechanisms by which loss of OCRL1 leads to the phenotypic manifestations of Lowe syndrome are currently unclear, in part, owing to the lack of an animal model that recapitulates the disease phenotype. Here, we describe a zebrafish model for Lowe syndrome using stable and transient suppression of OCRL1 expression. Deficiency of OCRL1, which is enriched in the brain, leads to neurological defects similar to those reported in Lowe syndrome patients, namely increased susceptibility to heat-induced seizures and cystic brain lesions. In OCRL1-deficient embryos, Akt signalling is reduced and there is both increased apoptosis and reduced proliferation, most strikingly in the neural tissue. Rescue experiments indicate that catalytic activity and binding to the vesicle coat protein clathrin are essential for OCRL1 function in these processes. Our results indicate a novel role for OCRL1 in neural development, and support a model whereby dysregulation of phosphoinositide metabolism and clathrin-mediated membrane traffic leads to the neurological symptoms of Lowe syndrome.
Collapse
|
39
|
OCRL controls trafficking through early endosomes via PtdIns4,5P₂-dependent regulation of endosomal actin. EMBO J 2011; 30:4970-85. [PMID: 21971085 DOI: 10.1038/emboj.2011.354] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 09/05/2011] [Indexed: 11/08/2022] Open
Abstract
Mutations in the phosphatidylinositol 4,5-bisphosphate (PtdIns4,5P(2)) 5-phosphatase OCRL cause Lowe syndrome, which is characterised by congenital cataracts, central hypotonia, and renal proximal tubular dysfunction. Previous studies have shown that OCRL interacts with components of the endosomal machinery; however, its role in endocytosis, and thus the pathogenic mechanisms of Lowe syndrome, have remained elusive. Here, we show that via its 5-phosphatase activity, OCRL controls early endosome (EE) function. OCRL depletion impairs the recycling of multiple classes of receptors, including megalin (which mediates protein reabsorption in the kidney) that are retained in engorged EEs. These trafficking defects are caused by ectopic accumulation of PtdIns4,5P(2) in EEs, which in turn induces an N-WASP-dependent increase in endosomal F-actin. Our data provide a molecular explanation for renal proximal tubular dysfunction in Lowe syndrome and highlight that tight control of PtdIns4,5P(2) and F-actin at the EEs is essential for exporting cargoes that transit this compartment.
Collapse
|
40
|
Koca G, Atilgan HI, Demirel K, Diri A, Korkmaz M. Poor Tc-99m dimercaptosuccinic acid uptake, re-evaluation with Tc-99m MAG3 scintigraphy in Lowe syndrome. Indian J Nucl Med 2011; 26:185-7. [PMID: 23559713 PMCID: PMC3613624 DOI: 10.4103/0972-3919.106701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Tc-99m dimercaptosuccinic acid (DMSA) is filtered through the glomeruli and reabsorbed by the proximal tubules as low molecular weight proteins. In Lowe syndrome this mechanism is impaired and so poor DMSA uptake is seen. Poor DMSA uptake was shown in very few studies, but none mentioned normal Tc-99m MAG3 uptake. In this case, the patient had poor DMSA uptake, normal MAG3 uptake and a neurogenic bladder in anterior to the left kidney that attenuates left kidney.
Collapse
Affiliation(s)
- Gokhan Koca
- Department of Nuclear Medicine, Ministry of Health, Ankara Training and Research Hospital, Ulucanlar, Altindag, Ankara, Turkey
| | | | | | | | | |
Collapse
|
41
|
Actin regulation during abscission: unexpected roles of Rab35 and endocytic transport. Cell Res 2011; 21:1283-5. [PMID: 21844893 DOI: 10.1038/cr.2011.131] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|
42
|
Lozanovski VJ, Ristoska-Bojkovska N, Korneti P, Gucev Z, Tasic V. OCRL1 mutation in a boy with Dent disease, mild mental retardation, but without cataracts. World J Pediatr 2011; 7:280-3. [PMID: 21822997 DOI: 10.1007/s12519-011-0312-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 01/11/2010] [Indexed: 11/27/2022]
Abstract
BACKGROUND Oculocerebrorenal (Lowe) syndrome is an X-linked multisystem disease characterized by renal proximal tubulopathy, mental retardation, and congenital cataracts. We present a 19-year-old boy who was found to have low molecular weight proteinuria, hypercalciuria, mild generalized hyperaminoaciduria and intermittent microscopic hematuria at the age of 3. METHODS Standard clinical and biochemical examinations and mutational analysis of the CLNC5 and OCRL1 gene were performed for the patient. RESULTS The patient fulfilled diagnostic criteria for Dent disease, but lacked mutation in CLCN5. Sequencing of candidate genes revealed a mutation in his OCRL1 gene, which encodes for enzyme PIP2 5-phosphatase. The enzyme was not detected by western blot analysis, and decreased activity of the enzyme PIP2 5-phosphatase was observed in cultured skin fibroblasts. The boy had only mild mental retardation, mildly elevated muscle enzymes, but no neurological deficit or congenital cataracts, which are typical for Lowe syndrome. CONCLUSIONS Children with Dent phenotype who lack CLCN5 mutation should be tested for OCRL1 mutation. OCRL1 mutations may present with mild clinical features and are not necessarily associated with congenital cataracts.
Collapse
|
43
|
Claverie-Martín F, Ramos-Trujillo E, García-Nieto V. Dent's disease: clinical features and molecular basis. Pediatr Nephrol 2011; 26:693-704. [PMID: 20936522 DOI: 10.1007/s00467-010-1657-0] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 08/27/2010] [Accepted: 09/06/2010] [Indexed: 02/08/2023]
Abstract
Dent's disease is an X-linked recessive renal tubulopathy characterized by low-molecular-weight proteinuria (LMWP), hypercalciuria, nephrocalcinosis, nephrolithiasis, and progressive renal failure. LMWP is the most constant feature, while the other clinical manifestations show wide variability. Patients also present variable manifestations of proximal tubule dysfunctions, such as aminoaciduria, glucosuria, hyperphosphaturia, kaliuresis, and uricosuria, consistent with renal Fanconi syndrome. Dent's disease affects mainly male children, and female carriers are generally asymptomatic. In two-thirds of patients, the disease is caused by mutations in the CLCN5 gene, which encodes the electrogenic chloride/proton exchanger ClC-5. A few patients have mutations in OCRL1, the gene associated with the oculocerebrorenal syndrome of Lowe, which encodes a phosphatidylinositol-4,5-biphosphate-5-phosphatase (OCRL1). Both ClC-5 and OCRL1 are involved in the endocytic pathway for reabsorption of LMW proteins in the proximal tubule. This review will provide an overview of the important phenotypic characteristics of Dent's disease and summarize the molecular data that have significantly increased our comprehension of the mechanisms causing this disease.
Collapse
Affiliation(s)
- Félix Claverie-Martín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
| | | | | |
Collapse
|
44
|
Fairley KF, Leighton PW, Kincaid-Smith P. Familial Visual Defects Associated with Polycystic Kidney and Medullary Sponge Kidney. BRITISH MEDICAL JOURNAL 2011; 1:1060-3. [PMID: 20789756 DOI: 10.1136/bmj.1.5337.1060] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
45
|
Şimşek E, Şimşek T, Dallar Y, Can Ö, Willems PJ. A novel pathogenic DNA variation in the OCRL1 gene in Lowe syndrome. J Clin Res Pediatr Endocrinol 2011; 3:29-31. [PMID: 21448331 PMCID: PMC3065313 DOI: 10.4274/jcrpe.v3i1.06] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 01/06/2011] [Indexed: 12/01/2022] Open
Abstract
The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by congenital cataracts, renal tubular dysfunction, cognitive problems and maladaptive behavior. The syndrome is caused by pathogenic DNA variations in the X-linked OCRL1 gene. A 24-month-old boy was referred to our hospital with delayed motor milestones, hypotonia, involuntary purposeless movements of hands and feet, congenital cataract, severe feeding difficulties, and failure to thrive. Physical examination at the age of 24 months revealed a body weight of 7350 g (-5.1 SDS). Length was 71 cm (-5.1 SDS) and head circumference 45 cm (-3.9 SDS). He had deep-set small eyes, frontal bossing, flat occiput, parietal prominence, bilateral congenital cataract, cryptorchid left testis, joint hypermobility, decreased muscle tone, and hyporeflexia. Biochemical analysis revealed the characteristic findings of renal Fanconi syndrome. Genetic analysis showed a novel pathogenic DNA variation (c.1528C>T) in exon 15 of the OCRL1 gene. Clinical findings and genetic analysis confirmed the diagnosis of OCRL syndrome.
Collapse
Affiliation(s)
- Enver Şimşek
- Division of Pediatric Endocrinology, Department of Pediatrics, School of Medicine, Eskisehir Osmangazi University, Eskisehir, Turkey.
| | - Tülay Şimşek
- Department of Glaucoma, Ulucanlar Eye Research and Training Hospital, Ankara, Turkey
| | - Yıldız Dallar
- Department of Pediatrics, Ankara Research and Training Hospital, Ankara, Turkey
| | - Önder Can
- Department of Pediatrics, Ankara Research and Training Hospital, Ankara, Turkey
| | | |
Collapse
|
46
|
Draaken M, Giesen CA, Kesselheim AL, Jabs R, Aretz S, Kugaudo M, Chrzanowska KH, Krajewska-Walasek M, Ludwig M. Maternal de novo triple mosaicism for two single OCRL nucleotide substitutions (c.1736A>T, c.1736A>G) in a Lowe syndrome family. Hum Genet 2011; 129:513-9. [PMID: 21225285 DOI: 10.1007/s00439-010-0944-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 12/30/2010] [Indexed: 11/29/2022]
Abstract
Since the identification of the Lowe's oculocerebrorenal syndrome gene, more than 100 distinct OCRL mutations have been observed. Germline mosaicism has rarely been detected in Lowe families; however, the presence of mosaic mutations, in particular triple mosaicism, may often remain undiagnosed. In the course of OCRL analysis in a Polish family, the index case showed a hemizygous nucleotide transition (c.1736A>G, p.His507Arg). Gene analysis in the patient's mother not only provided evidence that she is a carrier of the mutant allele transmitted to her son but also showed an additional c.1736A>T (p.His507Leu) transversion affecting the same base position. DNA from a mouthwash sample from the mother showed a similar fluorescence intensity pattern at the affected nucleotide. These data, together with the findings that maternal grandparents solely showed wildtype sequence, implied a de novo mosaicism in the mother. Triple X syndrome was ruled out by karyotype analysis and a partial or complete gene duplication could be excluded. Allele-specific amplification confirmed the results of three alleles being present in the mother. The amount of wildtype allele detected in qPCR implied the presence of cells solely harboring c.1736A and single-cell PCR experiments confirmed the presence of non-mutant cells in the mother's blood. These data suggest that the mutations observed are the result of two de novo events in early embryogenesis of the mother. To the best of our knowledge, this is the first observation of triple mosaicism at a single nucleotide.
Collapse
Affiliation(s)
- Markus Draaken
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Abstract
PURPOSE To report a patient with a tumor-like corneal keloid. METHODS Retrospective review of clinical features and histopathologic findings. RESULTS A 68-year-old woman with a remote history of an orbital tumor treated with radiation developed a corneal tumor. A biopsy of the tumor showed fibrocellular tissue, and her blind painful eye was enucleated. Pathologic findings in the enucleated eye showed that the corneal mass was consistent with a large keloid. CONCLUSIONS A corneal keloid may clinically appear as a large corneal tumor.
Collapse
Affiliation(s)
- Jesse J Jung
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, USA
| | | | | |
Collapse
|
48
|
Kwiatkowska K. One lipid, multiple functions: how various pools of PI(4,5)P(2) are created in the plasma membrane. Cell Mol Life Sci 2010; 67:3927-46. [PMID: 20559679 PMCID: PMC11115911 DOI: 10.1007/s00018-010-0432-5] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/01/2010] [Accepted: 06/02/2010] [Indexed: 01/25/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] is a minor lipid of the inner leaflet of the plasma membrane that controls the activity of numerous proteins and serves as a source of second messengers. This multifunctionality of PI(4,5)P(2) relies on mechanisms ensuring transient appearance of PI(4,5)P(2) clusters in the plasma membrane. One such mechanism involves phosphorylation of PI(4)P to PI(4,5)P(2) by the type I phosphatidylinositol-4-phosphate 5-kinases (PIP5KI) at discrete membrane locations coupled with PI(4)P delivery/synthesis at the plasma membrane. Simultaneously, both PI(4)P and PI(4,5)P(2) participate in anchoring PIP5KI at the plasma membrane via electrostatic bonds. PIP5KI isoforms are also selectively recruited and activated at the plasma membrane by Rac1, talin, or AP-2 to generate PI(4,5)P(2) in ruffles and lamellipodia, focal contacts, and clathrin-coated pits. In addition, PI(4,5)P(2) can accumulate at sphingolipid/cholesterol-based rafts following activation of distinct membrane receptors or be sequestered in a reversible manner due to electrostatic constrains posed by proteins like MARCKS.
Collapse
Affiliation(s)
- Katarzyna Kwiatkowska
- Laboratory of Plasma Membrane Receptors, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
| |
Collapse
|
49
|
Won JH, Lee MJ, Park JS, Chung H, Kim JK, Shim JS. Multiple epidermal cysts in lowe syndrome. Ann Dermatol 2010; 22:444-6. [PMID: 21165217 DOI: 10.5021/ad.2010.22.4.444] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 01/15/2010] [Accepted: 01/19/2010] [Indexed: 11/08/2022] Open
Abstract
Lowe syndrome is a rare genetic disease that appears to cause various clinical symptoms involving the eye, nervous system, and kidney. While a mutation of the OCRL1 gene is known to be responsible for this syndrome, the exact pathophysiology remains unclear. Various multi-organ symptoms are characteristic of Lowe syndrome, but skin lesions have rarely been described. Recently, mechanisms for the association of Lowe syndrome and skin lesions have been proposed. We report this case of Lowe syndrome involving multiple epidermal cysts on the scalp in a 6-year-old male child.
Collapse
Affiliation(s)
- Jong Hoon Won
- Department of Dermatology, Catholic University of Daegu School of Medicine, Daegu, Korea
| | | | | | | | | | | |
Collapse
|
50
|
Liu Y, Bankaitis VA. Phosphoinositide phosphatases in cell biology and disease. Prog Lipid Res 2010; 49:201-17. [PMID: 20043944 PMCID: PMC2873057 DOI: 10.1016/j.plipres.2009.12.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/03/2009] [Accepted: 12/03/2009] [Indexed: 01/10/2023]
Abstract
Phosphoinositides are essential signaling molecules linked to a diverse array of cellular processes in eukaryotic cells. The metabolic interconversions of these phospholipids are subject to exquisite spatial and temporal regulation executed by arrays of phosphatidylinositol (PtdIns) and phosphoinositide-metabolizing enzymes. These include PtdIns- and phosphoinositide-kinases that drive phosphoinositide synthesis, and phospholipases and phosphatases that regulate phosphoinositide degradation. In the past decade, phosphoinositide phosphatases have emerged as topics of particular interest. This interest is driven by the recent appreciation that these enzymes represent primary mechanisms for phosphoinositide degradation, and because of their ever-increasing connections with human diseases. Herein, we review the biochemical properties of six major phosphoinositide phosphatases, the functional involvements of these enzymes in regulating phosphoinositide metabolism, the pathologies that arise from functional derangements of individual phosphatases, and recent ideas concerning the involvements of phosphoinositide phosphatases in membrane traffic control.
Collapse
Affiliation(s)
- Yang Liu
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
| | - Vytas A. Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
| |
Collapse
|