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Azotla-Vilchis C, Merino-Jiménez C, Ríos-Castro E, Aragón J, Ceja V, Montanez C. Identification of dystrophin Dp71d Δ71-associated proteins in PC12 cells by quantitative proteomics. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2024:141049. [PMID: 39349271 DOI: 10.1016/j.bbapap.2024.141049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 09/10/2024] [Accepted: 09/25/2024] [Indexed: 10/02/2024]
Abstract
Dystrophin Dp71 is essential for the development of the nervous system. Its alteration is associated with intellectual disability. Different Dp71 isoforms are generated by alternative splicing; however, their functions have not been fully described. Here, we identified Dp71dΔ71-associated proteins to understand the complex functions. PC12 cells, stably transfected with pTRE2pur-Myc/Dp71dΔ71 or pTRE2pur-Myc empty vector (EV), were analyzed by immunoprecipitation coupled with quantitative proteomics and a UHPLC ACQUITY M-Class. Spectral data were acquired in an MS with electrospray ionization and ion mobility separation Synapt G2-Si operated with data-independent acquisition and ion mobility spectrometry using high-definition multiplexed MS/MS mode. We used the Hi3 method to quantify absolutely every protein detected. A total of 121 proteins were quantified with Progenesis QI software and the database UP000002494. Seven new proteins associated with Dp71dΔ71 were selected with at least 2-fold quantity between immunoprecipitated proteins of PC12-Myc/Dp71dΔ71 versus PC12-EV cells. These results revealed new proteins that interact with Dp71dΔ71, including β-tubulin, S-adenosylmethionine synthase isoform type-2, adapter molecule crk, helicase with zinc finger 2, WD repeat domain 93, cyclin-L2 and myosin-10, which are related to cell migration and/or cell growth. The results lay the foundation for future research on the relationship between these proteins and Dp71 isoforms.
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Affiliation(s)
- Coztli Azotla-Vilchis
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
| | - Candelaria Merino-Jiménez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
| | - Emmanuel Ríos-Castro
- Unidad de Genómica, Proteómica y Metabolómica, LaNSE, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
| | - Jorge Aragón
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
| | - Víctor Ceja
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
| | - Cecilia Montanez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico.
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González-Reyes M, Aragón J, Sánchez-Trujillo A, Rodríguez-Martínez G, Duarte K, Eleftheriou E, Barnier JV, Naquin D, Thermes C, Romo-Yáñez J, Roger JE, Rendon A, Vaillend C, Montanez C. Expression of Dystrophin Dp71 Splice Variants Is Temporally Regulated During Rodent Brain Development. Mol Neurobiol 2024:10.1007/s12035-024-04232-2. [PMID: 38802640 DOI: 10.1007/s12035-024-04232-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 05/13/2024] [Indexed: 05/29/2024]
Abstract
Dystrophin Dp71 is the major product of the Duchenne muscular dystrophy (DMD) gene in the brain, and its loss in DMD patients and mouse models leads to cognitive impairments. Dp71 is expressed as a range of proteins generated by alternative splicing of exons 71 to 74 and 78, classified in the main Dp71d and Dp71f groups that contain specific C-terminal ends. However, it is unknown whether each isoform has a specific role in distinct cell types, brain regions, and/or stages of brain development. In the present study, we characterized the expression of Dp71 isoforms during fetal (E10.5, E15.5) and postnatal (P1, P7, P14, P21 and P60) mouse and rat brain development. We finely quantified the expression of several Dp71 transcripts by RT-PCR and cloning assays in samples from whole-brain and distinct brain structures. The following Dp71 transcripts were detected: Dp71d, Dp71d∆71, Dp71d∆74, Dp71d∆71,74, Dp71d∆71-74, Dp71f, Dp71f∆71, Dp71f∆74, Dp71f∆71,74, and Dp71fΔ71-74. We found that the Dp71f isoform is the main transcript expressed at E10.5 (> 80%), while its expression is then progressively reduced and replaced by the expression of isoforms of the Dp71d group from E15.5 to postnatal and adult ages. This major finding was confirmed by third-generation nanopore sequencing. In addition, we found that the level of expression of specific Dp71 isoforms varies as a function of postnatal stages and brain structure. Our results suggest that Dp71 isoforms have different and complementary roles during embryonic and postnatal brain development, likely taking part in a variety of maturation processes in distinct cell types.
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Affiliation(s)
- Mayram González-Reyes
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
- Institut des Neurosciences Paris Saclay, Université Paris-Saclay, CNRS, Saclay, 91400, France
| | - Jorge Aragón
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
- Institut de la Vision, Sorbonne Université-INSERM-CNRS, 17 rue Moreau, Paris, 75012, France
| | - Alejandra Sánchez-Trujillo
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
| | - Griselda Rodríguez-Martínez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
- Laboratorio de Investigación en Inmunología y Proteómica, Hospital Infantil de México Federico Gómez, Mexico City, Mexico
| | - Kevin Duarte
- Institut des Neurosciences Paris Saclay, Université Paris-Saclay, CNRS, Saclay, 91400, France
| | - Evangelia Eleftheriou
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, 91198, France
| | - Jean-Vianney Barnier
- Institut des Neurosciences Paris Saclay, Université Paris-Saclay, CNRS, Saclay, 91400, France
| | - Delphine Naquin
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, 91198, France
| | - Claude Thermes
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, 91198, France
| | - José Romo-Yáñez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico
- Institut de la Vision, Sorbonne Université-INSERM-CNRS, 17 rue Moreau, Paris, 75012, France
- Coordinación de Endocrinología Ginecológica y Perinatal, Instituto Nacional de Perinatología, Mexico City, Mexico
| | - Jérome E Roger
- Institut des Neurosciences Paris Saclay, Université Paris-Saclay, CNRS, Saclay, 91400, France
- CERTO-Retina France, Saclay, 91400, France
| | - Alvaro Rendon
- Institut de la Vision, Sorbonne Université-INSERM-CNRS, 17 rue Moreau, Paris, 75012, France
| | - Cyrille Vaillend
- Institut des Neurosciences Paris Saclay, Université Paris-Saclay, CNRS, Saclay, 91400, France.
| | - Cecilia Montanez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Mexico City, Mexico.
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Nuclear transport and subcellular localization of the dystrophin Dp71 and Dp40 isoforms in the PC12 cell line. Biochem Biophys Res Commun 2022; 630:125-132. [PMID: 36155058 DOI: 10.1016/j.bbrc.2022.09.035] [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: 08/31/2022] [Accepted: 09/08/2022] [Indexed: 11/21/2022]
Abstract
The shortest dystrophins, Dp71 and Dp40, are transcribed from the DMD gene through an internal promoter located in intron 62. These proteins are the main product of the DMD gene in the nervous system and have been involved in various functions related to cellular differentiation and proliferation as well as other cellular processes. Dp71 mRNA undergoes alternative splicing that results in different Dp71 protein isoforms. The subcellular localization of some of these isoforms in the PC12 cell line has been previously reported, and a differential subcellular distribution was observed, which suggests a particular role for each isoform. With the aim of obtaining information on their function, this study identified factors involved in the nuclear transport of Dp71 and Dp40 isoforms in the PC12 cell line. Cell cultures were treated with specific nuclear import/export inhibitors to determine the Dp71 isoform transport routes. The results showed that all isoforms of Dp71 and Dp40 included in the analysis have the ability to enter the cell nucleus through α/β importin, and the main route of nuclear export for Dp71 isoforms is through the exportin CRM1, which is not the case for Dp40.
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Farea M, Maeta K, Nishio H, Matsuo M. Human Dystrophin Dp71ab Enhances the Proliferation of Myoblasts Across Species But Not Human Nonmyoblast Cells. Front Cell Dev Biol 2022; 10:877612. [PMID: 35547811 PMCID: PMC9081641 DOI: 10.3389/fcell.2022.877612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/05/2022] [Indexed: 11/13/2022] Open
Abstract
Dystrophin Dp71 is an isoform produced from the Dp71 promoter in intron 62 of the DMD gene, mutations in which cause Duchenne muscular dystrophy. Dp71 is involved in various cellular processes and comprises more than 10 isoforms produced by alternative splicing. Dp71ab, in which both exons 71 and 78 are deleted, has a hydrophobic C-terminus that is hydrophilic in Dp71. Therefore, Dp71ab is believed to have different roles from Dp71. Previously, we reported that Dp71ab enhanced the proliferation of human myoblasts. Here, we further characterized Dp71ab, focusing on the activation of cell proliferation. Dp71ab increased the proliferation of immortalized human myoblasts in a dose-dependent manner. In contrast, Dp71 suppressed proliferation in a dose-dependent manner. Consistent with these opposite effects, eGFP-tagged Dp71ab and mCherry-tagged Dp71 showed different cellular distributions, with Dp71ab mostly in the nucleus. Notably, human Dp71ab enhanced the proliferation of rat and mouse myoblasts. Despite these findings, human Dp71ab did not enhance the proliferation of human nonmyoblast cells, including rhabdomyosarcoma cells. We concluded that Dp71ab is a myoblast-specific proliferation enhancer. In further studies, Dp71ab will be employed for the expansion of myoblasts in clinical settings.
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Affiliation(s)
- Manal Farea
- Research Center for Locomotion Biology, Kobe Gakuin University, Kobe, Japan
| | - Kazuhiro Maeta
- Research Center for Locomotion Biology, Kobe Gakuin University, Kobe, Japan
- KNC Department of Nucleic Acid Drug Discovery, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan
| | - Hisahide Nishio
- Research Center for Locomotion Biology, Kobe Gakuin University, Kobe, Japan
- Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan
| | - Masafumi Matsuo
- Research Center for Locomotion Biology, Kobe Gakuin University, Kobe, Japan
- KNC Department of Nucleic Acid Drug Discovery, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan
- *Correspondence: Masafumi Matsuo,
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Overexpression of the dystrophins Dp40 and Dp40 L170P modifies neurite outgrowth and the protein expression profile of PC12 cells. Sci Rep 2022; 12:1410. [PMID: 35082358 PMCID: PMC8791958 DOI: 10.1038/s41598-022-05271-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/04/2022] [Indexed: 11/08/2022] Open
Abstract
Dp40 is ubiquitously expressed including the central nervous system. In addition to being present in the nucleus, membrane, and cytoplasm, Dp40 is detected in neurites and postsynaptic spines in hippocampal neurons. Although Dp40 is expressed from the same promoter as Dp71, its role in the cognitive impairment present in Duchenne muscular dystrophy patients is still unknown. Here, we studied the effects of overexpression of Dp40 and Dp40L170P during the neuronal differentiation of PC12 Tet-On cells. We found that Dp40 overexpression increased the percentage of PC12 cells with neurites and neurite length, while Dp40L170P overexpression decreased them compared to Dp40 overexpression. Two-dimensional gel electrophoresis analysis showed that the protein expression profile was modified in nerve growth factor-differentiated PC12-Dp40L170P cells compared to that of the control cells (PC12 Tet-On). The proteins α-internexin and S100a6, involved in cytoskeletal structure, were upregulated. The expression of vesicle-associated membrane proteins increased in differentiated PC12-Dp40 cells, in contrast to PC12-Dp40L170P cells, while neurofilament light-chain was decreased in both differentiated cells. These results suggest that Dp40 has an important role in the neuronal differentiation of PC12 cells through the regulation of proteins involved in neurofilaments and exocytosis of synaptic vesicles, functions that might be affected in PC12-Dp40L170P.
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Fujimoto T, Yaoi T, Tanaka H, Itoh K. Dystroglycan regulates proper expression, submembranous localization and subsequent phosphorylation of Dp71 through physical interaction. Hum Mol Genet 2021; 29:3312-3326. [PMID: 32996569 DOI: 10.1093/hmg/ddaa217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/28/2020] [Accepted: 09/25/2020] [Indexed: 11/12/2022] Open
Abstract
Dystrophin-dystroglycan complex (DGC) plays important roles for structural integrity and cell signaling, and its defects cause progressive muscular degeneration and intellectual disability. Dystrophin short product, Dp71, is abundantly expressed in multiple tissues other than muscle and is suspected of contributing to cognitive functions; however, its molecular characteristics and relation to dystroglycan (DG) remain unknown. Here, we report that DG physically interacts with Dp71 in cultured cells. Intriguingly, DG expression positively and DG knockdown negatively affected the steady-state expression, submembranous localization and subsequent phosphorylation of Dp71. Mechanistically, two EF-hand regions along with a ZZ motif of Dp71 mediate its association with the transmembrane proximal region, amino acid residues 788-806, of DG cytoplasmic domain. Most importantly, the pathogenic point mutations of Dp71, C272Y in the ZZ motif or L170del in the second EF-hand region, impaired its binding to DG, submembranous localization and phosphorylation of Dp71, indicating the relevance of DG-dependent Dp71 regulatory mechanism to pathophysiological conditions. Since Dp140, another dystrophin product, was also regulated by DG in the same manner as Dp71, our results uncovered a tight molecular relation between DG and dystrophin, which has broad implications for understanding the DGC-related cellular physiology and pathophysiology.
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Affiliation(s)
- Takahiro Fujimoto
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Takeshi Yaoi
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Hidekazu Tanaka
- Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Kyoko Itoh
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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Paúl-González S, Aragón J, Rodríguez-Martínez G, Romo-Yáñez J, Montanez C. Differential expression of Dp71 and Dp40 isoforms in proliferating and differentiated neural stem cells: Identification of Dp40 splicing variants. Biochem Biophys Res Commun 2021; 560:152-158. [PMID: 33989907 DOI: 10.1016/j.bbrc.2021.03.142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 03/25/2021] [Indexed: 11/29/2022]
Abstract
Dp71 and Dp40 are the main products of the DMD gene in the central nervous system, and they are developmentally regulated from the early stages of embryonic development to adulthood. To further study the roles of Dp71 and Dp40 during cell proliferation and neural differentiation, we analyzed Dp71/Dp40 isoform expression at the mRNA level by RT-PCR assays to identify alternative splicing (AS) in the isoforms expressed in rat neural stem/progenitor cells (NSPCs) and in differentiated cells (neurons and glia). We found that proliferating NSPCs expressed Dp71d, Dp71dΔ71, Dp71f, Dp71fΔ71, Dp71dΔ74 and Dp40, as well as two Dp40 isoforms: Dp40Δ63,64 and Dp40Δ64-67. In differentiated cells we also found the expression of Dp71d, Dp71dΔ71, Dp71f, Dp71fΔ71 and Dp40. However, the expression frequencies were different in both stages. In addition, in differentiated cells, we found Dp71fΔ71-74, and interestingly, we did not find the expression of Dp71dΔ74 or the newly identified Dp40 isoforms. In this work we show that NSPC differentiation is accompanied by changes in Dp71/Dp40 isoform expression, suggesting different roles for these isoforms in NSPCs proliferation and neuronal differentiation, and we describe, for the first time, alternative splicing of Dp40.
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Affiliation(s)
- Sandra Paúl-González
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jorge Aragón
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Griselda Rodríguez-Martínez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - José Romo-Yáñez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Cecilia Montanez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Ciudad de México, Mexico.
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First Identification of RNA-Binding Proteins That Regulate Alternative Exons in the Dystrophin Gene. Int J Mol Sci 2020; 21:ijms21207803. [PMID: 33096920 PMCID: PMC7589424 DOI: 10.3390/ijms21207803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 12/29/2022] Open
Abstract
The Duchenne muscular dystrophy (DMD) gene has a complex expression pattern regulated by multiple tissue-specific promoters and by alternative splicing (AS) of the resulting transcripts. Here, we used an RNAi-based approach coupled with DMD-targeted RNA-seq to identify RNA-binding proteins (RBPs) that regulate splicing of its skeletal muscle isoform (Dp427m) in a human muscular cell line. A total of 16 RBPs comprising the major regulators of muscle-specific splicing events were tested. We show that distinct combinations of RBPs maintain the correct inclusion in the Dp427m of exons that undergo spatio-temporal AS in other dystrophin isoforms. In particular, our findings revealed the complex networks of RBPs contributing to the splicing of the two short DMD exons 71 and 78, the inclusion of exon 78 in the adult Dp427m isoform being crucial for muscle function. Among the RBPs tested, QKI and DDX5/DDX17 proteins are important determinants of DMD exon inclusion. This is the first large-scale study to determine which RBP proteins act on the physiological splicing of the DMD gene. Our data shed light on molecular mechanisms contributing to the expression of the different dystrophin isoforms, which could be influenced by a change in the function or expression level of the identified RBPs.
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Dystrophin Dp71ab is monoclonally expressed in human satellite cells and enhances proliferation of myoblast cells. Sci Rep 2020; 10:17123. [PMID: 33051488 PMCID: PMC7553993 DOI: 10.1038/s41598-020-74157-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/28/2020] [Indexed: 12/15/2022] Open
Abstract
Dystrophin Dp71 is the smallest isoform of the DMD gene, mutations in which cause Duchenne muscular dystrophy (DMD). Dp71 has also been shown to have roles in various cellular processes. Stem cell-based therapy may be effective in treating DMD, but the inability to generate a sufficient number of stem cells remains a significant obstacle. Although Dp71 is comprised of many variants, Dp71 in satellite cells has not yet been studied. Here, the full-length Dp71 consisting of 18 exons from exons G1 to 79 was amplified by reverse transcription-PCR from total RNA of human satellite cells. The amplified product showed deletion of both exons 71 and 78 in all sequenced clones, indicating monoclonal expression of Dp71ab. Western blotting of the satellite cell lysate showed a band corresponding to over-expressed Dp71ab. Transfection of a plasmid expressing Dp71ab into human myoblasts significantly enhanced cell proliferation when compared to the cells transfected with the mock plasmid. However, transfection of the Dp71 expression plasmid encoding all 18 exons did not enhance myoblast proliferation. These findings indicated that Dp71ab, but not Dp71, is a molecular enhancer of myoblast proliferation and that transfection with Dp71ab may generate a high yield of stem cells for DMD treatment.
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10
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Naidoo M, Anthony K. Dystrophin Dp71 and the Neuropathophysiology of Duchenne Muscular Dystrophy. Mol Neurobiol 2020; 57:1748-1767. [PMID: 31836945 PMCID: PMC7060961 DOI: 10.1007/s12035-019-01845-w] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/22/2019] [Indexed: 12/13/2022]
Abstract
Duchenne muscular dystrophy (DMD) is caused by frameshift mutations in the DMD gene that prevent the body-wide translation of its protein product, dystrophin. Besides a severe muscle phenotype, cognitive impairment and neuropsychiatric symptoms are prevalent. Dystrophin protein 71 (Dp71) is the major DMD gene product expressed in the brain and mutations affecting its expression are associated with the DMD neuropsychiatric syndrome. As with dystrophin in muscle, Dp71 localises to dystrophin-associated protein complexes in the brain. However, unlike in skeletal muscle; in the brain, Dp71 is alternatively spliced to produce many isoforms with differential subcellular localisations and diverse cellular functions. These include neuronal differentiation, adhesion, cell division and excitatory synapse organisation as well as nuclear functions such as nuclear scaffolding and DNA repair. In this review, we first describe brain involvement in DMD and the abnormalities observed in the DMD brain. We then review the gene expression, RNA processing and functions of Dp71. We review genotype-phenotype correlations and discuss emerging cellular/tissue evidence for the involvement of Dp71 in the neuropathophysiology of DMD. The literature suggests changes observed in the DMD brain are neurodevelopmental in origin and that their risk and severity is associated with a cumulative loss of distal DMD gene products such as Dp71. The high risk of neuropsychiatric syndromes in Duchenne patients warrants early intervention to achieve the best possible quality of life. Unravelling the function and pathophysiological significance of dystrophin in the brain has become a high research priority to inform the development of brain-targeting treatments for Duchenne.
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Affiliation(s)
- Michael Naidoo
- Centre for Physical Activity and Life Sciences, Faculty of Arts, Science and Technology, University of Northampton, University Drive, Northampton, Northamptonshire, NN1 5PH, UK
| | - Karen Anthony
- Centre for Physical Activity and Life Sciences, Faculty of Arts, Science and Technology, University of Northampton, University Drive, Northampton, Northamptonshire, NN1 5PH, UK.
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11
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The dystrophin isoform Dp71e Δ71 is involved in neurite outgrowth and neuronal differentiation of PC12 cells. J Proteomics 2018; 191:80-87. [PMID: 29625189 DOI: 10.1016/j.jprot.2018.03.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/19/2018] [Accepted: 03/25/2018] [Indexed: 11/22/2022]
Abstract
The Dp71 protein is the most abundant dystrophin in the central nervous system (CNS). Several dystrophin Dp71 isoforms have been described and are classified into three groups, each with a different C-terminal end. However, the functions of Dp71 isoforms remain unknown. In the present study, we analysed the effect of Dp71eΔ71 overexpression on neuronal differentiation of PC12 Tet-On cells. Overexpression of dystrophin Dp71eΔ71 stimulates neuronal differentiation, increasing the percentage of cells with neurites and neurite length. According to 2-DE analysis, Dp71eΔ71 overexpression modified the protein expression profile of rat pheochromocytoma PC12 Tet-On cells that had been treated with neuronal growth factor (NGF) for nine days. Interestingly, all differentially expressed proteins were up-regulated compared to the control. The proteomic analysis showed that Dp71eΔ71 increases the expression of proteins with important roles in the differentiation process, such as HspB1, S100A6, and K8 proteins involved in the cytoskeletal structure and HCNP protein involved in neurotransmitter synthesis. The expression of neuronal marker TH was also up-regulated. Mass spectrometry data are available via ProteomeXchange with identifier PXD009114. SIGNIFICANCE: This study is the first to explore the role of the specific isoform Dp71eΔ71. The results obtained here support the hypothesis that the dystrophin Dp71eΔ71 isoform has an important role in the neurite outgrowth by regulating the levels of proteins involved in the cytoskeletal structure, such as HspB1, S100A6, and K8, and in neurotransmitter synthesis, such as HCNP and TH, biological processes required to stimulate neuronal differentiation.
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12
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Dp71 is regulated by phosphorylation and ubiquitin-proteasome system in neuronal cells. Biochem Biophys Res Commun 2017; 492:349-355. [PMID: 28851655 DOI: 10.1016/j.bbrc.2017.08.108] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 08/26/2017] [Indexed: 01/29/2023]
Abstract
The Dystrophin (Dp) gene is responsible for Duchenne muscular dystrophy (DMD), which is characterized by progressive muscular degeneration and variable degrees of cognitive impairment. Although Dp71 is the most abundant among the Dp isoforms in the brain, the regulatory mechanisms of the related expression levels have not been elucidated. In this study, we found that the constitutive expression levels of Dp71 in PC12 cells were sensitive to proteasomal inhibition. The ectopic expression of FLAG-tagged ubiquitin revealed that Dp71 was ubiquitinated intracellularly. Interestingly, proteasomal inhibition was accompanied by a posttranslational accumulation of modified Dp71, which was restored by protein phosphatase treatment in vitro, indicating that phosphorylation is responsible for the modification and affects the proteasome-dependent degradation of Dp71. Proteasomal activity-sensitive phosphorylated Dp71 is closely associated with syntrophin, a well-known binding partner of Dp71, and syntrophin is also regulated by proteasomal activity in a similar way to Dp71, suggesting that the posttranslational regulatory machinery for Dp71 level is coupled with Dp71-syntrophin molecular complex. Taken together, our results indicated that the expression levels of Dp71 are posttranslationally regulated by the phosphorylation-ubiquitin-proteasomal pathway, which may indicate the presence of regulatory mechanisms underlying the proteostasis of both Dp and its molecular complex, which may lead to better therapeutic approaches for the treatment of Dp-related diseases.
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Dystrophin Dp71 Isoforms Are Differentially Expressed in the Mouse Brain and Retina: Report of New Alternative Splicing and a Novel Nomenclature for Dp71 Isoforms. Mol Neurobiol 2017; 55:1376-1386. [PMID: 28127699 DOI: 10.1007/s12035-017-0405-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 01/12/2017] [Indexed: 12/27/2022]
Abstract
Multiple dystrophin Dp71 isoforms have been identified in rats, mice, and humans and in several cell line models. These Dp71 isoforms are produced by the alternative splicing of exons 71 to 74 and 78 and intron 77. Three main groups of Dp71 proteins are defined based on their C-terminal specificities: Dp71d, Dp71f, and Dp71e. Dp71 is highly expressed in the brain and retina; however, the specific isoforms present in these tissues have not been determined to date. In this work, we explored the expression of Dp71 isoforms in the mouse brain and retina using RT-PCR assays followed by the cloning of PCR products into the pGEM-T Easy vector, which was used to transform DH5α cells. Dp71-positive colonies were later analyzed by PCR multiplex and DNA sequencing to determine the alternative splicing. We thus demonstrated the expression of Dp71 transcripts corresponding to Dp71, Dp71a, Dp71c, Dp71b, Dp71ab, Dp71 Δ110, and novel Dp71 isoforms spliced in exon 74; 71 and 74; 71, 73 and 74; and 74 and 78, which we named Dp71d Δ74 , Dp71d Δ71,74 , Dp71d Δ71,73-74 , and Dp71f Δ74 , respectively. Additionally, we demonstrated that the Dp71d group of isoforms is highly expressed in the brain, while the Dp71f group predominates in the retina, at both the cDNA and protein levels. These findings suggest that distinct Dp71 isoforms may play different roles in the brain and retina.
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Merino-Jiménez C, Aragón J, Ceja V, Rodríguez-Martínez G, Cázares-Raga FE, Chardonnet S, Pionneau C, Rendon A, Montañez C. Dp71Δ78-79 dystrophin mutant stimulates neurite outgrowth in PC12 cells via upregulation and phosphorylation of HspB1. Proteomics 2016; 16:1331-40. [PMID: 26936078 DOI: 10.1002/pmic.201500211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 01/24/2016] [Accepted: 02/29/2016] [Indexed: 11/05/2022]
Abstract
PC12 cells acquire a neuronal phenotype in response to nerve growth factor (NGF). However, this phenotype is more efficiently achieved when the Dp71Δ78-79 dystrophin mutant is stably expressed in PC12-C11 cells. To investigate the effect of Dp71Δ78-79 overexpression on the protein profile of PC12-C11 cells, we compared the expression profiles of undifferentiated and NGF-differentiated PC12-C11 and PC12 cells by 2DE. In undifferentiated cultures, one protein was downregulated, and five were upregulated. Dp71Δ78-79 overexpression had a greater effect on differentiated cultures, with ten proteins downregulated and seven upregulated. The protein with the highest upregulation was HspB1. Changes in HspB1 expression were validated by Western blot and immunofluorescence analyses. Interestingly, the neurite outgrowth in PC12-C11 cells was affected by a polyclonal antibody against HspB1, and the level of HspB1 and HspB1Ser86 decreased, suggesting an important role for this protein in this cellular process. Our results show that Dp71Δ78-79 affects the expression level of some proteins and that the stimulated neurite outgrowth produced by this mutant is mainly through upregulation and phosphorylation of HspB1.
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Affiliation(s)
- Candelaria Merino-Jiménez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., México
| | - Jorge Aragón
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., México
| | - Víctor Ceja
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., México
| | - Griselda Rodríguez-Martínez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., México
| | - Febe E Cázares-Raga
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., México
| | - Solenne Chardonnet
- UPMC Univ Paris 06, UMS 2 Omique, Sorbonne Universités, Plateforme P3S, Paris, France.,UMS 29 Omique, INSERM, Plateforme P3S, Paris, France
| | - Cédric Pionneau
- UPMC Univ Paris 06, UMS 2 Omique, Sorbonne Universités, Plateforme P3S, Paris, France.,UMS 29 Omique, INSERM, Plateforme P3S, Paris, France
| | - Alvaro Rendon
- Institut de la Vision, INSERM UMR_S968, CNRS UMR_7210, Université Pierre et Marie Curie Paris 06, Paris, France
| | - Cecilia Montañez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., México
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