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Schäfer J, Wenck N, Janik K, Linnert J, Stingl K, Kohl S, Nagel-Wolfrum K, Wolfrum U. The Usher syndrome 1C protein harmonin regulates canonical Wnt signaling. Front Cell Dev Biol 2023; 11:1130058. [PMID: 36846582 PMCID: PMC9944737 DOI: 10.3389/fcell.2023.1130058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 01/23/2023] [Indexed: 02/11/2023] Open
Abstract
Human Usher syndrome (USH) is the most common form of hereditary combined deaf-blindness. USH is a complex genetic disorder, and the pathomechanisms underlying the disease are far from being understood, especially in the eye and retina. The USH1C gene encodes the scaffold protein harmonin which organizes protein networks due to binary interactions with other proteins, such as all USH proteins. Interestingly, only the retina and inner ear show a disease-related phenotype, although USH1C/harmonin is almost ubiquitously expressed in the human body and upregulated in colorectal cancer. We show that harmonin binds to β-catenin, the key effector of the canonical Wnt (cWnt) signaling pathway. We also demonstrate the interaction of the scaffold protein USH1C/harmonin with the stabilized acetylated β-catenin, especially in nuclei. In HEK293T cells, overexpression of USH1C/harmonin significantly reduced cWnt signaling, but a USH1C-R31* mutated form did not. Concordantly, we observed an increase in cWnt signaling in dermal fibroblasts derived from an USH1C R31*/R80Pfs*69 patient compared with healthy donor cells. RNAseq analysis reveals that both the expression of genes related to the cWnt signaling pathway and cWnt target genes were significantly altered in USH1C patient-derived fibroblasts compared to healthy donor cells. Finally, we show that the altered cWnt signaling was reverted in USH1C patient fibroblast cells by the application of Ataluren, a small molecule suitable to induce translational read-through of nonsense mutations, hereby restoring some USH1C expression. Our results demonstrate a cWnt signaling phenotype in USH establishing USH1C/harmonin as a suppressor of the cWnt/β-catenin pathway.
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Affiliation(s)
- Jessica Schäfer
- Institute of Molecular Physiology, Molecular Cell Biology and Photoreceptor Cell Biology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Nicole Wenck
- Institute of Molecular Physiology, Molecular Cell Biology and Photoreceptor Cell Biology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Katharina Janik
- Institute of Molecular Physiology, Molecular Cell Biology and Photoreceptor Cell Biology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Joshua Linnert
- Institute of Molecular Physiology, Molecular Cell Biology and Photoreceptor Cell Biology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Katarina Stingl
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Kerstin Nagel-Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology and Photoreceptor Cell Biology, Johannes Gutenberg University Mainz, Mainz, Germany,Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Uwe Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology and Photoreceptor Cell Biology, Johannes Gutenberg University Mainz, Mainz, Germany,*Correspondence: Uwe Wolfrum,
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2
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Lin Q, Zhou S, Huang Y, Huo Z, Chen C, Luo X, He J, Liu C, Zhang P. ANKS4B Restricts Replication of Zika Virus by Downregulating the Autophagy. Front Microbiol 2020; 11:1745. [PMID: 32793175 PMCID: PMC7387654 DOI: 10.3389/fmicb.2020.01745] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/03/2020] [Indexed: 12/21/2022] Open
Abstract
Infection of Zika virus (ZIKV) has become a severe threaten to global health while no specific drug is available. In this study, we explored the relationship between ZIKV and a cellular protein, ankyrin repeat and sterile motif domain containing 4b (ANKS4B). Our data revealed that the expression of ANKS4B in cultured cells and in neonatal mice was downregulated by ZIKV infection. The reduction of ANKS4B upon ZIKV infection was caused by decrease of two hepatocyte nuclear factors HNF1α and HNF4α. Through CRISPR/Cas9 gene editing system, we generated two ANKS4B knockout (KO) cell clones in A549 and Huh7 cells respectively. In the ANKS4B-KO cells, the viral replication levels including viral RNA, protein, and titer were significantly enhanced, which was reversed by trans-complementation of ANKS4B. ANKS4B did not affect the viral entry step, but impaired the autophagy induced by ZIKV infection. Furthermore, our data showed that inhibition of autophagy led to similar replication levels of ZIKV in ANKS4B-sufficient and ANKS4B-deficient cells, suggesting the antiviral effect of ANKS4B relied on its modulation on the autophagy. Therefore, our work identified ANKS4B as a new restriction factor of ZIKV.
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Affiliation(s)
- Quanshi Lin
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Shili Zhou
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yanxia Huang
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Zhiting Huo
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Cancan Chen
- Department of Pathology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xin Luo
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Junfang He
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Chao Liu
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Ping Zhang
- Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-sen University, Ministry of Education, Guangzhou, China.,Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
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3
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Graves MJ, Matoo S, Choi MS, Storad ZA, El Sheikh Idris RA, Pickles BK, Acharya P, Shinder PE, Arvay TO, Crawley SW. A cryptic sequence targets the adhesion complex scaffold ANKS4B to apical microvilli to promote enterocyte brush border assembly. J Biol Chem 2020; 295:12588-12604. [PMID: 32636301 DOI: 10.1074/jbc.ra120.013790] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/30/2020] [Indexed: 12/31/2022] Open
Abstract
Nutrient-transporting enterocytes interact with their luminal environment using a densely packed collection of apical microvilli known as the brush border. Assembly of the brush border is controlled by the intermicrovillar adhesion complex (IMAC), a protocadherin-based complex found at the tips of brush border microvilli that mediates adhesion between neighboring protrusions. ANKS4B is known to be an essential scaffold within the IMAC, although its functional properties have not been thoroughly characterized. We report here that ANKS4B is directed to the brush border using a noncanonical apical targeting sequence that maps to a previously unannotated region of the scaffold. When expressed on its own, this sequence targeted to microvilli in the absence of any direct interaction with the other IMAC components. Sequence analysis revealed a coiled-coil motif and a putative membrane-binding basic-hydrophobic repeat sequence within this targeting region, both of which were required for the scaffold to target and mediate brush border assembly. Size-exclusion chromatography of the isolated targeting sequence coupled with in vitro brush border binding assays suggests that it functions as an oligomer. We further show that the corresponding sequence found in the closest homolog of ANKS4B, the scaffold USH1G that operates in sensory epithelia as part of the Usher complex, lacks the inherent ability to target to microvilli. This study further defines the underlying mechanism of how ANKS4B targets to the apical domain of enterocytes to drive brush border assembly and identifies a point of functional divergence between the ankyrin repeat-based scaffolds found in the IMAC and Usher complex.
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Affiliation(s)
- Maura J Graves
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Samaneh Matoo
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Myoung Soo Choi
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Zachary A Storad
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | | | - Brooke K Pickles
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Prashun Acharya
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Paula E Shinder
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Taylen O Arvay
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
| | - Scott W Crawley
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA
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4
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Yao Q, Wang L, Mittal R, Yan D, Richmond MT, Denyer S, Requena T, Liu K, Varshney GK, Lu Z, Liu XZ. Transcriptomic Analyses of Inner Ear Sensory Epithelia in Zebrafish. Anat Rec (Hoboken) 2019; 303:527-543. [PMID: 31883312 DOI: 10.1002/ar.24331] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 08/01/2019] [Accepted: 11/18/2019] [Indexed: 12/25/2022]
Abstract
Analysis of gene expression has the potential to assist in the understanding of multiple cellular processes including proliferation, cell-fate specification, senesence, and activity in both healthy and disease states. Zebrafish model has been increasingly used to understand the process of hearing and the development of the vertebrate auditory system. Within the zebrafish inner ear, there are three otolith organs, each containing a sensory macula of hair cells. The saccular macula is primarily involved in hearing, the utricular macula is primarily involved in balance and the function of the lagenar macula is not completely understood. The goal of this study is to understand the transcriptional differences in the sensory macula associated with different otolith organs with the intention of understanding the genetic mechanisms responsible for the distinct role each organ plays in sensory perception. The sensory maculae of the saccule, utricle, and lagena were dissected out of adult Et(krt4:GFP)sqet4 zebrafish expressing green fluorescent protein in hair cells for transcriptional analysis. The total RNAs of the maculae were isolated and analyzed by RNA GeneChip microarray. Several of the differentially expressed genes are known to be involved in deafness, otolith development and balance. Gene expression among these otolith organs was very well conserved with less than 10% of genes showing differential expression. Data from this study will help to elucidate which genes are involved in hearing and balance. Furthermore, the findings of this study will assist in the development of the zebrafish model for human hearing and balance disorders. Anat Rec, 303:527-543, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Qi Yao
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida.,Department of Biology, University of Miami, Miami, Florida
| | - Lingyu Wang
- Department of Biology, University of Miami, Miami, Florida
| | - Rahul Mittal
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida
| | | | - Steven Denyer
- Department of Biology, University of Miami, Miami, Florida
| | - Teresa Requena
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma
| | - Kaili Liu
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma
| | - Gaurav K Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma
| | - Zhongmin Lu
- Department of Biology, University of Miami, Miami, Florida
| | - Xue Zhong Liu
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida.,Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, Hunan, China
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5
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Tyska MJ. Listen to your gut: Using adhesion to shape the surface of functionally diverse epithelia. Rare Dis 2016. [DOI: 10.1080/21675511.2016.1220469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
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6
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Mechanistic Basis of Organization of the Harmonin/USH1C-Mediated Brush Border Microvilli Tip-Link Complex. Dev Cell 2016; 36:179-89. [PMID: 26812017 DOI: 10.1016/j.devcel.2015.12.020] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/08/2015] [Accepted: 12/21/2015] [Indexed: 11/23/2022]
Abstract
Brush border microvilli are actin-based protrusions lining the apical surface of epithelial cells in intestines and proximal tubules of kidneys. While brush border microvilli resemble the relatively well-characterized stereocilia of hair cells, the mechanistic basis of tip-link complex organization in microvilli is poorly understood. Here, we have biochemically and structurally characterized the following pairs of interactions: protocadherin 24 and Harmonin (also known as USH1C or AIE-75), Harmonin and myosin VIIb (MYO7B), Harmonin and ANKS4B, and ANKS4B and MYO7B. We show that Harmonin, ANKS4B, and MYO7B form a stable ternary complex for anchoring microvilli tip-link cadherins. Despite having only Harmonin in common, the microvilli and the stereocilia tip-link complexes are formed via strikingly similar interaction modes. These results not only provide insight into the mechanistic bases of brush border microvilli formation and maintenance but may also be valuable for understanding some gut and/or kidney diseases caused by perturbations of brush border microvilli structures.
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7
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Crawley SW, Weck ML, Grega-Larson NE, Shifrin DA, Tyska MJ. ANKS4B Is Essential for Intermicrovillar Adhesion Complex Formation. Dev Cell 2016; 36:190-200. [PMID: 26812018 DOI: 10.1016/j.devcel.2015.12.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/11/2015] [Accepted: 12/21/2015] [Indexed: 11/29/2022]
Abstract
Transporting and sensory epithelial cells shape apical specializations using protocadherin-based adhesion. In the enterocyte brush border, protocadherin function requires a complex of cytoplasmic binding partners, although the composition of this complex and logic governing its assembly remain poorly understood. We found that ankyrin repeat and sterile α motif domain containing 4B (ANKS4B) localizes to the tips of adherent brush border microvilli and is essential for intermicrovillar adhesion. ANKS4B interacts with USH1C and MYO7B, which link protocadherins to the actin cytoskeleton. ANKS4B and USH1C also bind to the MYO7B cargo-binding tail at distinct sites. However, a tripartite complex only forms if ANKS4B and MYO7B are first activated by USH1C. This study uncovers an essential role for ANKS4B in brush border assembly, reveals a hierarchy in the molecular interactions that drive intermicrovillar adhesion, and informs our understanding of diseases caused by mutations in USH1C and ankyrin repeat proteins, such as Usher syndrome.
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Affiliation(s)
- Scott W Crawley
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Meredith L Weck
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Nathan E Grega-Larson
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - David A Shifrin
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21(st) Avenue South, Nashville, TN 37240-7935, USA.
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8
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Delestré L, Bakey Z, Prado C, Hoffmann S, Bihoreau MT, Lelongt B, Gauguier D. ANKS3 Co-Localises with ANKS6 in Mouse Renal Cilia and Is Associated with Vasopressin Signaling and Apoptosis In Vivo in Mice. PLoS One 2015; 10:e0136781. [PMID: 26327442 PMCID: PMC4556665 DOI: 10.1371/journal.pone.0136781] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 08/07/2015] [Indexed: 02/07/2023] Open
Abstract
Mutations in Ankyrin repeat and sterile alpha motif domain containing 6 (ANKS6) play a causative role in renal cyst formation in the PKD/Mhm(cy/+) rat model of polycystic kidney disease and in nephronophthisis in humans. A network of protein partners of ANKS6 is emerging and their functional characterization provides important clues to understand the role of ANKS6 in renal biology and in mechanisms involved in the formation of renal cysts. Following experimental confirmation of interaction between ANKS6and ANKS3 using a Yeast two hybrid system, we demonstrated that binding between the two proteins occurs through their sterile alpha motif (SAM) and that the amino acid 823 in rat ANSK6 is key for this interaction. We further showed their interaction by co-immunoprecipitation and showed in vivo in mice that ANKS3 is present in renal cilia. Downregulated expression of Anks3 in vivo in mice by Locked Nucleic Acid (LNA) modified antisense oligonucleotides was associated with increased transcription of vasopressin-induced genes, suggesting changes in renal water permeability, and altered transcription of genes encoding proteins involved in cilium structure, apoptosis and cell proliferation. These data provide experimental evidence of ANKS3-ANKS6 direct interaction through their SAM domain and co-localisation in mouse renal cilia, and shed light on molecular mechanisms indirectly mediated by ANKS6 in the mouse kidney, that may be affected by altered ANKS3-ANKS6 interaction. Our results contribute to improved knowledge of the structure and function of the network of proteins interacting with ANKS6, which may represent therapeutic targets in cystic diseases.
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Affiliation(s)
- Laure Delestré
- Sorbonne Universities, University Pierre and Marie Curie, University Paris Descartes, Sorbonne Paris Cité, INSERM, UMR_S1138, Cordeliers Research Centre, Paris, France
| | - Zeineb Bakey
- Sorbonne Universities, University Pierre and Marie Curie, UMR_S1155, Paris, France
- INSERM, UMR_S1155 Hôpital Tenon, Paris, France
| | - Cécilia Prado
- Sorbonne Universities, University Pierre and Marie Curie, University Paris Descartes, Sorbonne Paris Cité, INSERM, UMR_S1138, Cordeliers Research Centre, Paris, France
| | - Sigrid Hoffmann
- Medical Research Centre, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | | | - Brigitte Lelongt
- Sorbonne Universities, University Pierre and Marie Curie, UMR_S1155, Paris, France
- INSERM, UMR_S1155 Hôpital Tenon, Paris, France
| | - Dominique Gauguier
- Sorbonne Universities, University Pierre and Marie Curie, University Paris Descartes, Sorbonne Paris Cité, INSERM, UMR_S1138, Cordeliers Research Centre, Paris, France
- Institute of Cardiometabolism & Nutrition, Pitié-Salpêtrière Hospital, University Pierre and Marie-Curie, Paris, France
- * E-mail:
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9
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Yamagata K. Roles of HNF1α and HNF4α in pancreatic β-cells: lessons from a monogenic form of diabetes (MODY). VITAMINS AND HORMONES 2015; 95:407-23. [PMID: 24559927 DOI: 10.1016/b978-0-12-800174-5.00016-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mutations in the genes encoding hepatocyte nuclear factor (HNF)1α and HNF4α cause a monogenic form of diabetes mellitus known as maturity-onset diabetes of the young (MODY). The primary cause of MODY is an impairment of glucose-stimulated insulin secretion by pancreatic β-cells, indicating the important roles of HNF1α and HNF4α in β-cells. Large-scale genetic studies have clarified that the common variants of HNF1α and HNF4α genes are also associated with type 2 diabetes, suggesting that they are involved in the pathogenesis of both diseases. Recent experimental studies revealed that HNF1α controls both β-cell function and growth by regulating target genes such as glucose transporter 2, pyruvate kinase, collectrin, hepatocyte growth factor activator, and HNF4α. In contrast, HNF4α mainly regulates the function of β-cells. Although direct target genes of HNF4α in β-cells are largely unknown, we recently identified Anks4b as a novel target of HNF4α that regulates β-cell susceptibility to endoplasmic reticulum stress. Studies of MODY have led to a better understanding of the molecular mechanism of glucose-stimulated insulin secretion by pancreatic β-cells.
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Affiliation(s)
- Kazuya Yamagata
- Department of Medical Biochemistry, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
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10
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Sato Y, Hatta M, Karim MF, Sawa T, Wei FY, Sato S, Magnuson MA, Gonzalez FJ, Tomizawa K, Akaike T, Yoshizawa T, Yamagata K. Anks4b, a novel target of HNF4α protein, interacts with GRP78 protein and regulates endoplasmic reticulum stress-induced apoptosis in pancreatic β-cells. J Biol Chem 2012; 287:23236-45. [PMID: 22589549 DOI: 10.1074/jbc.m112.368779] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations of the HNF4A gene cause a form of maturity-onset diabetes of the young (MODY1) that is characterized by impairment of pancreatic β-cell function. HNF4α is a transcription factor belonging to the nuclear receptor superfamily (NR2A1), but its target genes in pancreatic β-cells are largely unknown. Here, we report that ankyrin repeat and sterile α motif domain containing 4b (Anks4b) is a target of HNF4α in pancreatic β-cells. Expression of Anks4b was decreased in both βHNF4α KO islets and HNF4α knockdown MIN6 β-cells, and HNF4α activated Anks4b promoter activity. Anks4b bound to glucose-regulated protein 78 (GRP78), a major endoplasmic reticulum (ER) chaperone protein, and overexpression of Anks4b enhanced the ER stress response and ER stress-associated apoptosis of MIN6 cells. Conversely, suppression of Anks4b reduced β-cell susceptibility to ER stress-induced apoptosis. These results indicate that Anks4b is a HNF4α target gene that regulates ER stress in β-cells by interacting with GRP78, thus suggesting that HNF4α is involved in maintenance of the ER.
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Affiliation(s)
- Yoshifumi Sato
- Department of Medical Biochemistry, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
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11
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Abstract
Usher syndrome (USH) comprises a group of autosomal recessively inherited disorders characterized by a dual sensory impairment of the audiovestibular and visual systems. Three major clinical subtypes (USH type I, USH type II and USH type III) are distinguished on the basis of the severity of the hearing loss, the presence or absence of vestibular dysfunction and the age of onset of retinitis pigmentosa (RP). Since the cloning of the first USH gene (MYO7A) in 1995, there have been remarkable advances in elucidating the genetic basis for this disorder, as evidence for 11 distinct loci have been obtained and genes for 9 of them have been identified. The USH genes encode proteins of different classes and families, including motor proteins, scaffold proteins, cell adhesion molecules and transmembrane receptor proteins. Extensive information has emerged from mouse models and molecular studies regarding pathogenesis of this disorder and the wide phenotypic variation in both audiovestibular and/or visual function. A unifying hypothesis is that the USH proteins are integrated into a protein network that regulates hair bundle morphogenesis in the inner ear. This review addresses genetics and pathological mechanisms of USH. Understanding the molecular basis of phenotypic variation and pathogenesis of USH is important toward discovery of new molecular targets for diagnosis, prevention and treatment of this debilitating disorder.
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Affiliation(s)
- Denise Yan
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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12
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Demontis F, Dahmann C. Characterization of the Drosophila ortholog of the human Usher Syndrome type 1G protein sans. PLoS One 2009; 4:e4753. [PMID: 19270738 PMCID: PMC2649435 DOI: 10.1371/journal.pone.0004753] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 02/09/2009] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The Usher syndrome (USH) is the most frequent deaf-blindness hereditary disease in humans. Deafness is attributed to the disorganization of stereocilia in the inner ear. USH1, the most severe subtype, is associated with mutations in genes encoding myosin VIIa, harmonin, cadherin 23, protocadherin 15, and sans. Myosin VIIa, harmonin, cadherin 23, and protocadherin 15 physically interact in vitro and localize to stereocilia tips in vivo, indicating that they form functional complexes. Sans, in contrast, localizes to vesicle-like structures beneath the apical membrane of stereocilia-displaying hair cells. How mutations in sans result in deafness and blindness is not well understood. Orthologs of myosin VIIa and protocadherin 15 have been identified in Drosophila melanogaster and their genetic analysis has identified essential roles in auditory perception and microvilli morphogenesis, respectively. PRINCIPAL FINDINGS Here, we have identified and characterized the Drosophila ortholog of human sans. Drosophila Sans is expressed in tubular organs of the embryo, in lens-secreting cone cells of the adult eye, and in microvilli-displaying follicle cells during oogenesis. Sans mutants are viable, fertile, and mutant follicle cells appear to form microvilli, indicating that Sans is dispensable for fly development and microvilli morphogenesis in the follicle epithelium. In follicle cells, Sans protein localizes, similar to its vertebrate ortholog, to intracellular punctate structures, which we have identified as early endosomes associated with the syntaxin Avalanche. CONCLUSIONS Our work is consistent with an evolutionary conserved function of Sans in vesicle trafficking. Furthermore it provides a significant basis for further understanding of the role of this Usher syndrome ortholog in development and disease.
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Affiliation(s)
- Fabio Demontis
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Christian Dahmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail:
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13
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Müller U. Cadherins and mechanotransduction by hair cells. Curr Opin Cell Biol 2008; 20:557-66. [PMID: 18619539 DOI: 10.1016/j.ceb.2008.06.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 06/12/2008] [Accepted: 06/13/2008] [Indexed: 10/21/2022]
Abstract
Mechanotransduction, the conversion of a mechanical stimulus into an electrical signal is crucial for our ability to hear and to maintain balance. Recent findings indicate that two members of the cadherin superfamily are components of the mechanotransduction machinery in sensory hair cells of the vertebrate inner ear. These studies show that cadherin 23 (CDH23) and protocadherin 15 (PCDH15) form several of the extracellular filaments that connect the stereocilia and kinocilium of a hair cell into a bundle. One of these filaments is the tip link that has been proposed to gate the mechanotransduction channel in hair cells. The extracellular domains of CDH23 and PCDH15 differ in their structure from classical cadherins and their cytoplasmic domains bind to distinct effectors, suggesting that evolutionary pressures have shaped the two cadherins for their function in mechanotransduction.
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Affiliation(s)
- Ulrich Müller
- Department of Cell Biology, Institute for Childhood and Neglected Disease, The Scripps Research Institute, La Jolla, CA 92037, USA.
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Overlack N, Maerker T, Latz M, Nagel-Wolfrum K, Wolfrum U. SANS (USH1G) expression in developing and mature mammalian retina. Vision Res 2007; 48:400-12. [PMID: 17923142 DOI: 10.1016/j.visres.2007.08.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 08/16/2007] [Accepted: 08/20/2007] [Indexed: 11/30/2022]
Abstract
The human Usher syndrome (USH) is the most common form of combined deaf-blindness. Usher type I (USH1), the most severe form, is characterized by profound congenital deafness, constant vestibular dysfunction and prepubertal-onset of retinitis pigmentosa. Five corresponding genes of the six USH1 genes have been cloned so far. The USH1G gene encodes the SANS (scaffold protein containing ankyrin repeats and SAM domain) protein which consists of protein motifs known to mediate protein-protein interactions. Recent studies indicated SANS function as a scaffold protein in the protein interactome related to USH. Here, we generated specific antibodies for SANS protein expression analyses. Our study revealed SANS protein expression in NIH3T3 fibroblasts, murine tissues containing ciliated cells and in mature and developing mammalian retinas. In mature retinas, SANS was localized in inner and outer plexiform retinal layers, and in the photoreceptor cell layer. Subcellular fractionations, tangential cryosections and immunocytochemistry revealed SANS in synaptic terminals, cell-cell adhesions of the outer limiting membrane and ciliary apparati of photoreceptor cells. Analyses of postnatal developmental stages of murine retinas demonstrated SANS localization in differentiating ciliary apparati and in fully developed cilia, synapses, and cell-cell adhesions of photoreceptor cells. Present data provide evidence that SANS functions as a scaffold protein in USH protein networks during ciliogenesis, at the mature ciliary apparatus, the ribbon synapse and the cell-cell adhesion of mammalian photoreceptor cells. Defects of SANS may cause dysfunction of the entire network leading to retinal degeneration, the ocular symptom characteristic for USH patients.
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Affiliation(s)
- Nora Overlack
- Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg-University of Mainz, Germany
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Reiners J, Wolfrum U. Molecular analysis of the supramolecular usher protein complex in the retina. Harmonin as the key protein of the Usher syndrome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 572:349-53. [PMID: 17249595 DOI: 10.1007/0-387-32442-9_49] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Jan Reiners
- Instiutut für Zoologie, Universität Mainz, 55099 Mainz, Germany
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Kremer H, van Wijk E, Märker T, Wolfrum U, Roepman R. Usher syndrome: molecular links of pathogenesis, proteins and pathways. Hum Mol Genet 2006; 15 Spec No 2:R262-70. [PMID: 16987892 DOI: 10.1093/hmg/ddl205] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Usher syndrome is the most common form of deaf-blindness. The syndrome is both clinically and genetically heterogeneous, and to date, eight causative genes have been identified. The proteins encoded by these genes are part of a dynamic protein complex that is present in hair cells of the inner ear and in photoreceptor cells of the retina. The localization of the Usher proteins and the phenotype in animal models indicate that the Usher protein complex is essential in the morphogenesis of the stereocilia bundle in hair cells and in the calycal processes of photoreceptor cells. In addition, the Usher proteins are important in the synaptic processes of both cell types. The association of other proteins with the complex indicates functional links to a number of basic cell-biological processes. Prominently present is the connection to the dynamics of the actin cytoskeleton, involved in cellular morphology, cell polarity and cell-cell interactions. The Usher protein complex can also be linked to the cadherins/catenins in the adherens junction-associated protein complexes, suggesting a role in cell polarity and tissue organization. A third link can be established to the integrin transmembrane signaling network. The Usher interactome, as outlined in this review, participates in pathways common in inner ear and retina that are disrupted in the Usher syndrome.
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Affiliation(s)
- Hannie Kremer
- Department of Otorhinolaryngology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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McHugh RK, Friedman RA. Genetics of hearing loss: Allelism and modifier genes produce a phenotypic continuum. ACTA ACUST UNITED AC 2006; 288:370-81. [PMID: 16550584 DOI: 10.1002/ar.a.20297] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent genetic and genomic studies have greatly advanced our knowledge of the structure and function of genes involved in hearing loss. We are starting to recognize, however, that many of these genes do not appear to follow traditional Mendelian expression patterns and are subject to the effects of allelism and modifier genes. This review presents two genes illustrative of this concept that have varied expression pattern such that they may produce either syndromic or nonsyndromic hearing loss. One of these genes, cadherin 23, produces a spectrum of phenotypic traits, including presbycusis, nonsyndromic prelingual hearing loss (DFNB12), and syndromic hearing loss as part of Usher syndrome (Usher 1D). Missense mutations in CDH23 have been associated with presbycusis and DFNB12, whereas null alleles cause the majority of Usher 1D. Modifier gene products that interact with cadherin 23 also affect the phenotypic spectrum. Similarly, allelsim in the gene encoding wolframin (WFS1) causes either a nonsyndromic dominant low-frequency hearing loss (DFNA6/14/38) or Wolfram syndrome. Missense mutations within a defined region are associated with DFNA6/14/38, while more severe mutations spanning WFS1 are found in Wolfram syndrome patients. The phenotypic spectrum of Wolfram syndrome is also hypothesized to be influenced by modifier genes products. These studies provide increasing evidence for the importance of modifier genes in elucidating the functional pathways of primary hearing loss genes. Characterizing modifier genes may result in better treatment options for patients with hearing loss and define new diagnostic and therapeutic targets.
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Affiliation(s)
- Richard K McHugh
- Section on Hereditary Disorders of the Ear, House Ear Institute, Los Angeles, California 90057, USA
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Reiners J, Nagel-Wolfrum K, Jürgens K, Märker T, Wolfrum U. Molecular basis of human Usher syndrome: deciphering the meshes of the Usher protein network provides insights into the pathomechanisms of the Usher disease. Exp Eye Res 2006; 83:97-119. [PMID: 16545802 DOI: 10.1016/j.exer.2005.11.010] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 11/15/2005] [Accepted: 11/21/2005] [Indexed: 11/17/2022]
Abstract
Usher syndrome (USH) is the most frequent cause of combined deaf-blindness in man. It is clinically and genetically heterogeneous and at least 12 chromosomal loci are assigned to three clinical USH types, namely USH1A-G, USH2A-C, USH3A (Davenport, S.L.H., Omenn, G.S., 1977. The heterogeneity of Usher syndrome. Vth Int. Conf. Birth Defects, Montreal; Petit, C., 2001. Usher syndrome: from genetics to pathogenesis. Annu. Rev. Genomics Hum. Genet. 2, 271-297). Mutations in USH type 1 genes cause the most severe form of USH. In USH1 patients, congenital deafness is combined with a pre-pubertal onset of retinitis pigmentosa (RP) and severe vestibular dysfunctions. Those with USH2 have moderate to severe congenital hearing loss, non-vestibular dysfunction and a later onset of RP. USH3 is characterized by variable RP and vestibular dysfunction combined with progressive hearing loss. The gene products of eight identified USH genes belong to different protein classes and families. There are five known USH1 molecules: the molecular motor myosin VIIa (USH1B); the two cell-cell adhesion cadherin proteins, cadherin 23 (USH1D) and protocadherin 15, (USH1F) and the scaffold proteins, harmonin (USH1C) and SANS (USH1G). In addition, two USH2 genes and one USH3A gene have been identified. The two USH2 genes code for the transmembrane protein USH2A, also termed USH2A ("usherin") and the G-protein-coupled 7-transmembrane receptor VLGR1b (USH2C), respectively, whereas the USH3A gene encodes clarin-1, a member of the clarin family which exhibits 4-transmembrane domains. Molecular analysis of USH1 protein function revealed that all five USH1 proteins are integrated into a protein network via binding to PDZ domains in the USH1C protein harmonin. Furthermore, this scaffold function of harmonin is supported by the USH1G protein SANS. Recently, we have shown that the USH2 proteins USH2A and VLGR1b as well as the candidate for USH2B, the sodium bicarbonate co-transporter NBC3, are also integrated into this USH protein network. In the inner ear, these interactions are essential for the differentiation of hair cell stereocilia but may also participate in the mechano-electrical signal transduction and the synaptic function of maturated hair cells. In the retina, the co-expression of all USH1 and USH2 proteins at the synapse of photoreceptor cells indicates that they are organized in an USH protein network there. The identification of the USH protein network indicates a common pathophysiological pathway in USH. Dysfunction or absence of any of the molecules in the mutual "interactome" related to the USH disease may lead to disruption of the network causing senso-neuronal degeneration in the inner ear and the retina, the clinical symptoms of USH.
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Affiliation(s)
- Jan Reiners
- Institute of Zoology, Department of Cell and Matrix Biology, Johannes Gutenberg University of Mainz, Müllerweg 6, D-55099 Mainz, Germany
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Reiners J, van Wijk E, Märker T, Zimmermann U, Jürgens K, te Brinke H, Overlack N, Roepman R, Knipper M, Kremer H, Wolfrum U. Scaffold protein harmonin (USH1C) provides molecular links between Usher syndrome type 1 and type 2. Hum Mol Genet 2005; 14:3933-43. [PMID: 16301216 DOI: 10.1093/hmg/ddi417] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Usher syndrome (USH) is the most frequent cause of combined deaf-blindness in man. USH is clinically and genetically heterogeneous with at least 11 chromosomal loci assigned to the three USH types (USH1A-G, USH2A-C, USH3A). Although the different USH types exhibit almost the same phenotype in human, the identified USH genes encode for proteins which belong to very different protein classes and families. We and others recently reported that the scaffold protein harmonin (USH1C-gene product) integrates all identified USH1 molecules in a USH1-protein network. Here, we investigated the relationship between the USH2 molecules and this USH1-protein network. We show a molecular interaction between the scaffold protein harmonin (USH1C) and the USH2A protein, VLGR1 (USH2C) and the candidate for USH2B, NBC3. We pinpoint these interactions to interactions between the PDZ1 domain of harmonin and the PDZ-binding motifs at the C-termini of the USH2 proteins and NBC3. We demonstrate that USH2A, VLGR1 and NBC3 are co-expressed with the USH1-protein harmonin in the synaptic terminals of both retinal photoreceptors and inner ear hair cells. In hair cells, these USH proteins are also localized in the signal uptaking stereocilia. Our data indicate that the USH2 proteins and NBC3 are further partners in the supramolecular USH-protein network in the retina and inner ear which shed new light on the function of USH2 proteins and the entire USH-protein network. These findings provide first evidence for a molecular linkage between the pathophysiology in USH1 and USH2. The organization of USH molecules in a mutual 'interactome' related to the disease can explain the common phenotype in USH.
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Affiliation(s)
- Jan Reiners
- Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University of Mainz, Germany
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