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Chakraborty D, Strayve DG, Makia MS, Conley SM, Kakahel M, Al-Ubaidi MR, Naash MI. Novel molecular mechanisms for Prph2-associated pattern dystrophy. FASEB J 2019; 34:1211-1230. [PMID: 31914632 DOI: 10.1096/fj.201901888r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/10/2019] [Accepted: 11/14/2019] [Indexed: 01/16/2023]
Abstract
Mutations in peripherin 2 (PRPH2) have been associated with retinitis pigmentosa (RP) and macular/pattern dystrophies, but the origin of this phenotypic variability is unclear. The majority of Prph2 mutations are located in the large intradiscal loop (D2), a region that contains seven cysteines involved in intra- and intermolecular disulfide bonding and protein folding. A mutation at cysteine 213, which is engaged in an intramolecular disulfide bond, leads to butterfly-shaped pattern dystrophy in humans, in sharp contrast to mutations in the adjacent cysteine at position 214 which result in RP. To help understand this unexpected phenotypic variability, we generated a knockin mouse line carrying the C213Y disease mutation. The mutant Prph2 protein lost the ability to oligomerize with rod outer segment membrane protein 1 (Rom1), but retained the ability to form homotetramers. C213Y heterozygotes had significantly decreased overall Prph2 levels as well as decreased rod and cone function. Critically, supplementation with extra wild-type Prph2 protein elicited improvements in Prph2 protein levels and rod outer segment structure, but not functional rescue in rods or cones. These findings suggest that not all interruptions of D2 loop intramolecular disulfide bonding lead to haploinsufficiency-related RP, but rather that more subtle changes can lead to mutant proteins stable enough to exert gain-of-function defects in rods and cones. This outcome highlights the difficulty in targeting Prph2-associated gain-of-function disease and suggests that elimination of the mutant protein will be a pre-requisite for any curative therapeutic strategy.
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Affiliation(s)
- Dibyendu Chakraborty
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Daniel G Strayve
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Mustafa S Makia
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Shannon M Conley
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Mashal Kakahel
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
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Strafella C, Caputo V, Pagliaroli G, Iozzo N, Campoli G, Carboni S, Peconi C, Galota RM, Zampatti S, Minozzi G, Novelli G, Giardina E, Cascella R. NGS Analysis for Molecular Diagnosis of Retinitis Pigmentosa (RP): Detection of a Novel Variant in PRPH2 Gene. Genes (Basel) 2019; 10:genes10100792. [PMID: 31614793 PMCID: PMC6826621 DOI: 10.3390/genes10100792] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/04/2019] [Accepted: 10/11/2019] [Indexed: 02/07/2023] Open
Abstract
This work describes the application of NGS for molecular diagnosis of RP in a family with a history of severe hypovision. In particular, the proband received a clinical diagnosis of RP on the basis of medical, instrumental examinations and his family history. The proband was subjected to NGS, utilizing a customized panel including 24 genes associated with RP and other retinal dystrophies. The NGS analysis revealed a novel missense variant (c.668T > A, I223N) in PRPH2 gene, which was investigated by segregation and bioinformatic analysis. The variant is located in the D2 loop domain of PRPH2, which is critical for protein activity. Bioinformatic analysis described the c.668T > A as a likely pathogenic variant. Moreover, a 3D model prediction was performed to better characterize the impact of the variant on the protein, reporting a disruption of the α-helical structures. As a result, the variant protein showed a substantially different conformation with respect to the wild-type PRPH2. The identified variant may therefore affect the oligomerization ability of the D2 loop and, ultimately, hamper PRPH2 proper functioning and localization. In conclusion, PRPH2_c.668T > A provided a molecular explanation of RP symptomatology, highlighting the clinical utility of NGS panels to facilitate genotype-phenotype correlations.
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Affiliation(s)
- Claudia Strafella
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
- Department of Biomedicine and Prevention, Tor Vergata University, 00133 Rome, Italy.
| | - Valerio Caputo
- Department of Biomedicine and Prevention, Tor Vergata University, 00133 Rome, Italy.
| | - Giulia Pagliaroli
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
| | - Nicola Iozzo
- Organi di Senso Department, University "la Sapienza", 00161 Rome, Italy.
| | - Giulia Campoli
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
| | - Stefania Carboni
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
| | - Cristina Peconi
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
| | | | - Stefania Zampatti
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
| | - Giulietta Minozzi
- Department of Veterinary Medicine, University of Milan, 20122 Milan, Italy.
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Tor Vergata University, 00133 Rome, Italy.
- Neuromed IRCSS, 86077 Pozzilli, Italy.
| | - Emiliano Giardina
- Molecular Genetics Laboratory UILDM, Santa Lucia Foundation, 00179 Rome, Italy.
- Department of Biomedicine and Prevention, Tor Vergata University, 00133 Rome, Italy.
| | - Raffaella Cascella
- Department of Biomedicine and Prevention, Tor Vergata University, 00133 Rome, Italy.
- Department of Biomedical Sciences, Catholic University Our Lady of Good Counsel, 1000 Tirana, Albania.
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Purushothaman G, Thiruvenkatam V. High Yield Expression of Recombinant CD151 in E. coli and a Structural Insight into Cholesterol Binding Domain. Mol Biotechnol 2019; 61:905-915. [PMID: 31541430 DOI: 10.1007/s12033-019-00212-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
CD151 is an abundantly expressed eukaryotic transmembrane protein on the cell surface. It is involved in cell adhesion, angiogenesis and signal transduction as well in disease conditions such as cancer and viral infections. However, the molecular mechanism of CD151 activation is poorly understood due to the lack of structural information. By considering the difficulties in expressing the membrane protein in E. coli, herein we introduce the strategic design for the effective expression of recombinant CD151 protein in E. coli with high yield, that would aid for the structural studies. CD151 having four transmembrane domain (TMD's) along with small and a large extracellular loop (LEL) is constructed in parts to enhance the soluble expression of the protein attached with fusion tag. This has led to the high yield of the recombinant CD151 protein in the designed constructs. The recombinant CD151 protein is characterized and confirmed by western blot, CD and Mass peptide fingerprint. The molecular dynamics simulations (MDS) for the full-length CD151 shows conformational changes in the LEL of the protein in the presence and absence of cholesterol and indicate the certainty of closed and open conformation of CD151 based on cholesterol binding. The MDS results have led to the understanding of the possible underlying mechanism for the activation of the CD151 protein.
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Affiliation(s)
- Gayathri Purushothaman
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Simkheda, Palaj, Gandhinagar, 382355, Gujarat, India
| | - Vijay Thiruvenkatam
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Simkheda, Palaj, Gandhinagar, 382355, Gujarat, India.
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Peripherin-2 and Rom-1 have opposing effects on rod outer segment targeting of retinitis pigmentosa-linked peripherin-2 mutants. Sci Rep 2017; 7:2321. [PMID: 28539581 PMCID: PMC5443838 DOI: 10.1038/s41598-017-02514-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/12/2017] [Indexed: 12/30/2022] Open
Abstract
Mutations in the photoreceptor outer segment (OS) specific peripherin-2 lead to autosomal dominant retinitis pigmentosa (adRP). By contrast, mutations in the peripherin-2 homolog Rom-1 cause digenic RP in combination with certain heterozygous mutations in peripherin-2. The mechanisms underlying the differential role of peripherin-2 and Rom-1 in RP pathophysiology remained elusive so far. Here, focusing on two adRP-linked peripherin-2 mutants, P210L and C214S, we analyzed the binding characteristics, protein assembly, and rod OS targeting of wild type (perWT), mutant peripherin-2 (perMT), or Rom-1 complexes, which can be formed in patients heterozygous for peripherin-2 mutations. Both mutants are misfolded and lead to decreased binding to perWT and Rom-1. Furthermore, both mutants are preferentially forming non-covalent perMT-perMT, perWT-perMT, and Rom-1-perMT dimers. However, only perWT-perMT, but not perMT-perMT or Rom-1-perMT complexes could be targeted to murine rod OS. Our study provides first evidence that non-covalent perWT-perMT dimers can be targeted to rod OS. Finally, our study unravels unexpected opposing roles of perWT and Rom-1 in rod OS targeting of adRP-linked peripherin-2 mutants and suggests a new treatment strategy for the affected individuals.
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Pakdaman Y, Sanchez-Guixé M, Kleppe R, Erdal S, Bustad HJ, Bjørkhaug L, Haugarvoll K, Tzoulis C, Heimdal K, Knappskog PM, Johansson S, Aukrust I. In vitro characterization of six STUB1 variants in spinocerebellar ataxia 16 reveals altered structural properties for the encoded CHIP proteins. Biosci Rep 2017; 37:BSR20170251. [PMID: 28396517 PMCID: PMC5408658 DOI: 10.1042/bsr20170251] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 11/24/2022] Open
Abstract
Spinocerebellar ataxia, autosomal recessive 16 (SCAR16) is caused by biallelic mutations in the STIP1 homology and U-box containing protein 1 (STUB1) gene encoding the ubiquitin E3 ligase and dimeric co-chaperone C-terminus of Hsc70-interacting protein (CHIP). It has been proposed that the disease mechanism is related to CHIP's impaired E3 ubiquitin ligase properties and/or interaction with its chaperones. However, there is limited knowledge on how these mutations affect the stability, folding, and protein structure of CHIP itself. To gain further insight, six previously reported pathogenic STUB1 variants (E28K, N65S, K145Q, M211I, S236T, and T246M) were expressed as recombinant proteins and studied using limited proteolysis, size-exclusion chromatography (SEC), and circular dichroism (CD). Our results reveal that N65S shows increased CHIP dimerization, higher levels of α-helical content, and decreased degradation rate compared with wild-type (WT) CHIP. By contrast, T246M demonstrates a strong tendency for aggregation, a more flexible protein structure, decreased levels of α-helical structures, and increased degradation rate compared with WT CHIP. E28K, K145Q, M211I, and S236T also show defects on structural properties compared with WT CHIP, although less profound than what observed for N65S and T246M. In conclusion, our results illustrate that some STUB1 mutations known to cause recessive SCAR16 have a profound impact on the protein structure, stability, and ability of CHIP to dimerize in vitro. These results add to the growing understanding on the mechanisms behind the disorder.
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Affiliation(s)
- Yasaman Pakdaman
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Monica Sanchez-Guixé
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Rune Kleppe
- K.G. Jebsen Centre for Neuropsychiatric Disorders, Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Sigrid Erdal
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Helene J Bustad
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Lise Bjørkhaug
- Department of Biomedical Laboratory Sciences and Chemical Engineering, Western Norway University of Applied Sciences, Bergen, Norway
| | - Kristoffer Haugarvoll
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Charalampos Tzoulis
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Ketil Heimdal
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Per M Knappskog
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- K.G. Jebsen Centre for Neuropsychiatric Disorders, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Stefan Johansson
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- K.G. Jebsen Centre for Neuropsychiatric Disorders, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Ingvild Aukrust
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
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