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Zhang SX, Wang JJ, Starr CR, Lee EJ, Park KS, Zhylkibayev A, Medina A, Lin JH, Gorbatyuk M. The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease. Prog Retin Eye Res 2024; 98:101231. [PMID: 38092262 PMCID: PMC11056313 DOI: 10.1016/j.preteyeres.2023.101231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.
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Affiliation(s)
- Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - Josh J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Christopher R Starr
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eun-Jin Lee
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Assylbek Zhylkibayev
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Jonathan H Lin
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Marina Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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Calame DG, Emrick LT. Functional genomics and small molecules in mitochondrial neurodevelopmental disorders. Neurotherapeutics 2024; 21:e00316. [PMID: 38244259 PMCID: PMC10903096 DOI: 10.1016/j.neurot.2024.e00316] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/16/2023] [Accepted: 01/02/2024] [Indexed: 01/22/2024] Open
Abstract
Mitochondria are critical for brain development and homeostasis. Therefore, pathogenic variation in the mitochondrial or nuclear genome which disrupts mitochondrial function frequently results in developmental disorders and neurodegeneration at the organismal level. Large-scale application of genome-wide technologies to individuals with mitochondrial diseases has dramatically accelerated identification of mitochondrial disease-gene associations in humans. Multi-omic and high-throughput studies involving transcriptomics, proteomics, metabolomics, and saturation genome editing are providing deeper insights into the functional consequence of mitochondrial genomic variation. Integration of deep phenotypic and genomic data through allelic series continues to uncover novel mitochondrial functions and permit mitochondrial gene function dissection on an unprecedented scale. Finally, mitochondrial disease-gene associations illuminate disease mechanisms and thereby direct therapeutic strategies involving small molecules and RNA-DNA therapeutics. This review summarizes progress in functional genomics and small molecule therapeutics in mitochondrial neurodevelopmental disorders.
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Affiliation(s)
- Daniel G Calame
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
| | - Lisa T Emrick
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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Macintosh J, Thiffault I, Pastinen T, Sztriha L, Bernard G. A Recurrent De Novo Variant in EIF2AK2 Causes a Hypomyelinating Leukodystrophy. Child Neurol Open 2023; 10:2329048X231176673. [PMID: 37284702 PMCID: PMC10240855 DOI: 10.1177/2329048x231176673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/29/2023] [Accepted: 05/01/2023] [Indexed: 06/08/2023] Open
Abstract
De novo pathogenic variants in EIF2AK2 have recently been reported as a novel genetic cause of leukoencephalopathy. Here, we describe a male individual who presented in the first year of life with clinical features resembling Pelizaeus-Merzbacher disease (PMD), including nystagmus, hypotonia, and global developmental delay, and which later progressed to include ataxia and spasticity. Brain MRI at the age of two revealed diffuse hypomyelination. This report adds to the limited number of individuals published and further reinforces de novo variants in EIF2AK2 as a molecular cause of a leukodystrophy that clinically and radiologically resembles PMD.
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Affiliation(s)
- Julia Macintosh
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Isabelle Thiffault
- Genomic Medicine Center, Children’s Mercy Hospital, Kansas City, MO, USA
- University of Missouri Kansas City School of Medicine, Kansas City, MO, USA
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO, USA
| | - Tomi Pastinen
- Genomic Medicine Center, Children’s Mercy Hospital, Kansas City, MO, USA
- University of Missouri Kansas City School of Medicine, Kansas City, MO, USA
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO, USA
| | - László Sztriha
- Department of Pediatrics Szent-Györgyi Albert Medical Center, University of Szeged, Szeged, Hungary
| | - Geneviève Bernard
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
- Department Specialized Medicine, Division of Medical Genetics, McGill University Health Center, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
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4
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Kamble VS, Pachpor TA, Khandagale SB, Wagh VV, Khare SP. Translation initiation and dysregulation of initiation factors in rare diseases. GENE REPORTS 2022. [DOI: 10.1016/j.genrep.2022.101738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Waller SE, Morales‐Briceño H, Williams L, Mohammad SS, Fellner A, Kumar KR, Tchan M, Fung VS. Possible
EIF2AK2
‐Associated Stress‐Related Neurological Decompensation with Combined Dystonia and Striatal Lesions. Mov Disord Clin Pract 2021; 9:240-244. [DOI: 10.1002/mdc3.13384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 11/03/2021] [Accepted: 11/10/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Sophie E. Waller
- Movement Disorders Unit, Neurology Department Westmead Hospital Westmead New South Wales Australia
| | - Hugo Morales‐Briceño
- Movement Disorders Unit, Neurology Department Westmead Hospital Westmead New South Wales Australia
- Sydney Medical School University of Sydney Sydney NSW Australia
| | - Laura Williams
- Movement Disorders Unit, Neurology Department Westmead Hospital Westmead New South Wales Australia
| | - Shekeeb S. Mohammad
- The Children's Hospital at Westmead Clinical School University of Sydney Westmead New South Wales Australia
| | - Avi Fellner
- Raphael Recanati Genetics Institute, Rabin Medical Center, Beilinson Hospital Petah Tikva Israel
- The Neurology Department Rabin Medical Center, Belinson Hospital Petah Tikva Israel
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research Darlinghurst New South Wales Australia
| | - Kishore R. Kumar
- Sydney Medical School University of Sydney Sydney NSW Australia
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research Darlinghurst New South Wales Australia
- Molecular Medicine Laboratory and Neurology Department Concord Repatriation General Hospital Concord New South Wales Australia
| | - Michel Tchan
- Sydney Medical School University of Sydney Sydney NSW Australia
- Department of Clinical Genetics Westmead Hospital Westmead New South Wales Australia
| | - Victor S.C. Fung
- Movement Disorders Unit, Neurology Department Westmead Hospital Westmead New South Wales Australia
- Sydney Medical School University of Sydney Sydney NSW Australia
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English AM, Green KM, Moon SL. A (dis)integrated stress response: Genetic diseases of eIF2α regulators. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 13:e1689. [PMID: 34463036 DOI: 10.1002/wrna.1689] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 01/28/2023]
Abstract
The integrated stress response (ISR) is a conserved mechanism by which eukaryotic cells remodel gene expression to adapt to intrinsic and extrinsic stressors rapidly and reversibly. The ISR is initiated when stress-activated protein kinases phosphorylate the major translation initiation factor eukaryotic translation initiation factor 2ɑ (eIF2ɑ), which globally suppresses translation initiation activity and permits the selective translation of stress-induced genes including important transcription factors such as activating transcription factor 4 (ATF4). Translationally repressed messenger RNAs (mRNAs) and noncoding RNAs assemble into cytoplasmic RNA-protein granules and polyadenylated RNAs are concomitantly stabilized. Thus, regulated changes in mRNA translation, stability, and localization to RNA-protein granules contribute to the reprogramming of gene expression that defines the ISR. We discuss fundamental mechanisms of RNA regulation during the ISR and provide an overview of a growing class of genetic disorders associated with mutant alleles of key translation factors in the ISR pathway. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA in Disease and Development > RNA in Disease Translation > Translation Regulation RNA in Disease and Development > RNA in Development.
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Affiliation(s)
- Alyssa M English
- Department of Human Genetics, Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Katelyn M Green
- Department of Chemistry, Department of Human Genetics, Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Stephanie L Moon
- Department of Human Genetics, Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan, USA
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