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Shafie A, Ashour AA, Anwar S, Anjum F, Hassan MI. Exploring molecular mechanisms, therapeutic strategies, and clinical manifestations of Huntington's disease. Arch Pharm Res 2024; 47:571-595. [PMID: 38764004 DOI: 10.1007/s12272-024-01499-w] [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: 12/18/2023] [Accepted: 05/02/2024] [Indexed: 05/21/2024]
Abstract
Huntington's disease (HD) is a paradigm of a genetic neurodegenerative disorder characterized by the expansion of CAG repeats in the HTT gene. This extensive review investigates the molecular complexities of HD by highlighting the pathogenic mechanisms initiated by the mutant huntingtin protein. Adverse outcomes of HD include mitochondrial dysfunction, compromised protein clearance, and disruption of intracellular signaling, consequently contributing to the gradual deterioration of neurons. Numerous therapeutic strategies, particularly precision medicine, are currently used for HD management. Antisense oligonucleotides, such as Tominersen, play a leading role in targeting and modulating the expression of mutant huntingtin. Despite the promise of these therapies, challenges persist, particularly in improving delivery systems and the necessity for long-term safety assessments. Considering the future landscape, the review delineates promising directions for HD research and treatment. Innovations such as Clustered regularly interspaced short palindromic repeats associated system therapies (CRISPR)-based genome editing and emerging neuroprotective approaches present unprecedented opportunities for intervention. Collaborative interdisciplinary endeavors and a more insightful understanding of HD pathogenesis are on the verge of reshaping the therapeutic landscape. As we navigate the intricate landscape of HD, this review serves as a guide for unraveling the intricacies of this disease and progressing toward transformative treatments.
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Affiliation(s)
- Alaa Shafie
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, PO Box 11099, 21944, Taif, Saudi Arabia
| | - Amal Adnan Ashour
- Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, Faculty of Dentistry, Taif University, PO Box 11099, 21944, Taif, Saudi Arabia
| | - Saleha Anwar
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Farah Anjum
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, PO Box 11099, 21944, Taif, Saudi Arabia
| | - Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
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Tong H, Yang T, Xu S, Li X, Liu L, Zhou G, Yang S, Yin S, Li XJ, Li S. Huntington's Disease: Complex Pathogenesis and Therapeutic Strategies. Int J Mol Sci 2024; 25:3845. [PMID: 38612657 PMCID: PMC11011923 DOI: 10.3390/ijms25073845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/21/2024] [Accepted: 03/26/2024] [Indexed: 04/14/2024] Open
Abstract
Huntington's disease (HD) arises from the abnormal expansion of CAG repeats in the huntingtin gene (HTT), resulting in the production of the mutant huntingtin protein (mHTT) with a polyglutamine stretch in its N-terminus. The pathogenic mechanisms underlying HD are complex and not yet fully elucidated. However, mHTT forms aggregates and accumulates abnormally in neuronal nuclei and processes, leading to disruptions in multiple cellular functions. Although there is currently no effective curative treatment for HD, significant progress has been made in developing various therapeutic strategies to treat HD. In addition to drugs targeting the neuronal toxicity of mHTT, gene therapy approaches that aim to reduce the expression of the mutant HTT gene hold great promise for effective HD therapy. This review provides an overview of current HD treatments, discusses different therapeutic strategies, and aims to facilitate future therapeutic advancements in the field.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Xiao-Jiang Li
- Guangdong Key Laboratory of Non-Human Primate Research, Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, China; (H.T.); (T.Y.); (S.X.); (X.L.); (L.L.); (G.Z.); (S.Y.); (S.Y.)
| | - Shihua Li
- Guangdong Key Laboratory of Non-Human Primate Research, Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, China; (H.T.); (T.Y.); (S.X.); (X.L.); (L.L.); (G.Z.); (S.Y.); (S.Y.)
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Hoschek F, Natan J, Wagner M, Sathasivam K, Abdelmoez A, von Einem B, Bates GP, Landwehrmeyer GB, Neueder A. Huntingtin HTT1a is generated in a CAG repeat-length-dependent manner in human tissues. Mol Med 2024; 30:36. [PMID: 38459427 PMCID: PMC10924374 DOI: 10.1186/s10020-024-00801-2] [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: 11/10/2023] [Accepted: 02/19/2024] [Indexed: 03/10/2024] Open
Abstract
BACKGROUND The disease-causing mutation in Huntington disease (HD) is a CAG trinucleotide expansion in the huntingtin (HTT) gene. The mutated CAG tract results in the production of a small RNA, HTT1a, coding for only exon 1 of HTT. HTT1a is generated by a block in the splicing reaction of HTT exon 1 to exon 2 followed by cleavage in intron 1 and polyadenylation. Translation of HTT1a leads to the expression of the highly toxic HTT exon 1 protein fragment. We have previously shown that the levels of HTT1a expression in mouse models of HD is dependent on the CAG repeat length. However, these data are lacking for human tissues. METHODS To answer this question, we developed highly sensitive digital PCR assays to determine HTT1a levels in human samples. These assays allow the absolute quantification of transcript numbers and thus also facilitate the comparison of HTT1a levels between tissues, cell types and across different studies. Furthermore, we measured CAG repeat sizes for every sample used in the study. Finally, we analysed our data with ANOVA and linear modelling to determine the correlation of HTT1a expression levels with CAG repeat sizes. RESULTS In summary, we show that HTT1a is indeed expressed in a CAG repeat-length-dependent manner in human post mortem brain tissues as well as in several peripheral cell types. In particular, PBMCs show a statistically significant positive correlation of HTT1a expression with CAG repeat length, and elevated HTT1a expression levels even in the adult-onset CAG repeat range. CONCLUSIONS Our results show that HTT1a expression occurs throughout a wide range of tissues and likely with all CAG lengths. Our data from peripheral sample sources demonstrate that HTT1a is indeed generated throughout the body in a CAG repeat-length-dependent manner. Therefore, the levels of HTT1a might be a sensitive marker of disease state and/or progression and should be monitored over time, especially in clinical trials targeting HTT expression.
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Affiliation(s)
- Franziska Hoschek
- Department of Neurology, University Hospital Ulm, 89081, Ulm, Germany
| | - Julia Natan
- Department of Neurology, University Hospital Ulm, 89081, Ulm, Germany
| | - Maximilian Wagner
- Department of Neurology, University Hospital Ulm, 89081, Ulm, Germany
| | - Kirupa Sathasivam
- Huntington's Disease Centre, Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, WC1N 3BG, London, UK
| | - Alshaimaa Abdelmoez
- Department of Neurology, University Hospital Ulm, 89081, Ulm, Germany
- Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt
| | - Björn von Einem
- Department of Neurology, University Hospital Ulm, 89081, Ulm, Germany
| | - Gillian P Bates
- Huntington's Disease Centre, Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, WC1N 3BG, London, UK
| | | | - Andreas Neueder
- Department of Neurology, University Hospital Ulm, 89081, Ulm, Germany.
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Birajdar SV, Mazahir F, Alam MI, Kumar A, Yadav AK. Repurposing and clinical attributes of antidiabetic drugs for the treatment of neurodegenerative disorders. Eur J Pharmacol 2023; 961:176117. [PMID: 37907134 DOI: 10.1016/j.ejphar.2023.176117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 10/03/2023] [Accepted: 10/12/2023] [Indexed: 11/02/2023]
Abstract
The risk of neurodegeneration was found to be increased among people with type 2 diabetes mellitus (T2DM). Brain disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and others are considered neurodegenerative diseases and can be characterized by progressive loss of neurons. The deficiency of insulin, impaired signaling, and its resistance lead to alteration in the neuronal functioning of the brain. Insulin degrading enzyme (IDE) plays a significant role in the amyloid β metabolism, aggregation, and deposition of misfolded proteins in the brain's hippocampal and cortical neuronal regions. The insulin signaling via IP3 activation upregulates the IDE and could be a promising approach to regulate neurodegeneration. The repurposing of existing antidiabetic drugs such as Metformin, DPP-4 inhibitors, thiazolidinediones, glucagon-like peptides (GLP-1), sodium-glucose co-transport-2 (SGCT-2) inhibitors, and insulin could be an alternative and effective strategy to treat neurodegeneration via modulating insulin signaling, insulin resistance, IDE activity, oxidative stress, mitochondrial dysfunction, serum lipid profile and neuroinflammation in the brain. Antidiabetic medications reduce the risk of neuroinflammation, oxidative stress, and Aβ deposition by enhancing their clearance rate. The downregulation of IDE alters the degradation of Aβ monomers in the Tg2576 APP mice. Also, the treatment with metformin activated the AMPK pathway and suppressed mTOR and BACE-1 protein expression in the APP/PS1-induced mice model. Thus, the primary intention of this review is to explore the link between T2DM and neurodegenerative disorders, and the possible role of various antidiabetic drugs in the management of neurodegenerative disorders.
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Affiliation(s)
- Swapnali Vasant Birajdar
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER) Raebareli, Lucknow, 226002, Uttar Pradesh, India
| | - Farhan Mazahir
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER) Raebareli, Lucknow, 226002, Uttar Pradesh, India
| | - Md Imtiyaz Alam
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER) Raebareli, Lucknow, 226002, Uttar Pradesh, India
| | - Amit Kumar
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER) Raebareli, Lucknow, 226002, Uttar Pradesh, India
| | - Awesh K Yadav
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER) Raebareli, Lucknow, 226002, Uttar Pradesh, India.
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Hannan AJ. Expanding horizons of tandem repeats in biology and medicine: Why 'genomic dark matter' matters. Emerg Top Life Sci 2023; 7:ETLS20230075. [PMID: 38088823 PMCID: PMC10754335 DOI: 10.1042/etls20230075] [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: 10/25/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 12/30/2023]
Abstract
Approximately half of the human genome includes repetitive sequences, and these DNA sequences (as well as their transcribed repetitive RNA and translated amino-acid repeat sequences) are known as the repeatome. Within this repeatome there are a couple of million tandem repeats, dispersed throughout the genome. These tandem repeats have been estimated to constitute ∼8% of the entire human genome. These tandem repeats can be located throughout exons, introns and intergenic regions, thus potentially affecting the structure and function of tandemly repetitive DNA, RNA and protein sequences. Over more than three decades, more than 60 monogenic human disorders have been found to be caused by tandem-repeat mutations. These monogenic tandem-repeat disorders include Huntington's disease, a variety of ataxias, amyotrophic lateral sclerosis and frontotemporal dementia, as well as many other neurodegenerative diseases. Furthermore, tandem-repeat disorders can include fragile X syndrome, related fragile X disorders, as well as other neurological and psychiatric disorders. However, these monogenic tandem-repeat disorders, which were discovered via their dominant or recessive modes of inheritance, may represent the 'tip of the iceberg' with respect to tandem-repeat contributions to human disorders. A previous proposal that tandem repeats may contribute to the 'missing heritability' of various common polygenic human disorders has recently been supported by a variety of new evidence. This includes genome-wide studies that associate tandem-repeat mutations with autism, schizophrenia, Parkinson's disease and various types of cancers. In this article, I will discuss how tandem-repeat mutations and polymorphisms could contribute to a wide range of common disorders, along with some of the many major challenges of tandem-repeat biology and medicine. Finally, I will discuss the potential of tandem repeats to be therapeutically targeted, so as to prevent and treat an expanding range of human disorders.
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Affiliation(s)
- Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria 3010, Australia
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