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Krishnamurthy K, Pradhan RK. Emerging perspectives of synaptic biomarkers in ALS and FTD. Front Mol Neurosci 2024; 16:1279999. [PMID: 38249293 PMCID: PMC10796791 DOI: 10.3389/fnmol.2023.1279999] [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: 08/19/2023] [Accepted: 12/01/2023] [Indexed: 01/23/2024] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD) are debilitating neurodegenerative diseases with shared pathological features like transactive response DNA-binding protein of 43 kDa (TDP-43) inclusions and genetic mutations. Both diseases involve synaptic dysfunction, contributing to their clinical features. Synaptic biomarkers, representing proteins associated with synaptic function or structure, offer insights into disease mechanisms, progression, and treatment responses. These biomarkers can detect disease early, track its progression, and evaluate therapeutic efficacy. ALS is characterized by elevated neurofilament light chain (NfL) levels in cerebrospinal fluid (CSF) and blood, correlating with disease progression. TDP-43 is another key ALS biomarker, its mislocalization linked to synaptic dysfunction. In FTD, TDP-43 and tau proteins are studied as biomarkers. Synaptic biomarkers like neuronal pentraxins (NPs), including neuronal pentraxin 2 (NPTX2), and neuronal pentraxin receptor (NPTXR), offer insights into FTD pathology and cognitive decline. Advanced technologies, like machine learning (ML) and artificial intelligence (AI), aid biomarker discovery and drug development. Challenges in this research include technological limitations in detection, variability across patients, and translating findings from animal models. ML/AI can accelerate discovery by analyzing complex data and predicting disease outcomes. Synaptic biomarkers offer early disease detection, personalized treatment strategies, and insights into disease mechanisms. While challenges persist, technological advancements and interdisciplinary efforts promise to revolutionize the understanding and management of ALS and FTD. This review will explore the present comprehension of synaptic biomarkers in ALS and FTD and discuss their significance and emphasize the prospects and obstacles.
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Affiliation(s)
- Karrthik Krishnamurthy
- Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, United States
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Pisciottani A, Croci L, Lauria F, Marullo C, Savino E, Ambrosi A, Podini P, Marchioretto M, Casoni F, Cremona O, Taverna S, Quattrini A, Cioni JM, Viero G, Codazzi F, Consalez GG. Neuronal models of TDP-43 proteinopathy display reduced axonal translation, increased oxidative stress, and defective exocytosis. Front Cell Neurosci 2023; 17:1253543. [PMID: 38026702 PMCID: PMC10679756 DOI: 10.3389/fncel.2023.1253543] [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: 07/05/2023] [Accepted: 10/13/2023] [Indexed: 12/01/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive, lethal neurodegenerative disease mostly affecting people around 50-60 years of age. TDP-43, an RNA-binding protein involved in pre-mRNA splicing and controlling mRNA stability and translation, forms neuronal cytoplasmic inclusions in an overwhelming majority of ALS patients, a phenomenon referred to as TDP-43 proteinopathy. These cytoplasmic aggregates disrupt mRNA transport and localization. The axon, like dendrites, is a site of mRNA translation, permitting the local synthesis of selected proteins. This is especially relevant in upper and lower motor neurons, whose axon spans long distances, likely accentuating their susceptibility to ALS-related noxae. In this work we have generated and characterized two cellular models, consisting of virtually pure populations of primary mouse cortical neurons expressing a human TDP-43 fusion protein, wt or carrying an ALS mutation. Both forms facilitate cytoplasmic aggregate formation, unlike the corresponding native proteins, giving rise to bona fide primary culture models of TDP-43 proteinopathy. Neurons expressing TDP-43 fusion proteins exhibit a global impairment in axonal protein synthesis, an increase in oxidative stress, and defects in presynaptic function and electrical activity. These changes correlate with deregulation of axonal levels of polysome-engaged mRNAs playing relevant roles in the same processes. Our data support the emerging notion that deregulation of mRNA metabolism and of axonal mRNA transport may trigger the dying-back neuropathy that initiates motor neuron degeneration in ALS.
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Affiliation(s)
- Alessandra Pisciottani
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Laura Croci
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Fabio Lauria
- Institute of Biophysics, CNR Unit at Trento, Povo, Italy
| | - Chiara Marullo
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Elisa Savino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Alessandro Ambrosi
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Paola Podini
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Filippo Casoni
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Ottavio Cremona
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Stefano Taverna
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Angelo Quattrini
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Jean-Michel Cioni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Franca Codazzi
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - G. Giacomo Consalez
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
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Sharma VK, Singh TG, Mehta V, Mannan A. Biomarkers: Role and Scope in Neurological Disorders. Neurochem Res 2023; 48:2029-2058. [PMID: 36795184 DOI: 10.1007/s11064-023-03873-4] [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: 06/02/2022] [Revised: 01/19/2023] [Accepted: 01/21/2023] [Indexed: 02/17/2023]
Abstract
Neurological disorders pose a great threat to social health and are a major cause for mortality and morbidity. Effective drug development complemented with the improved drug therapy has made considerable progress towards easing symptoms associated with neurological illnesses, yet poor diagnosis and imprecise understanding of these disorders has led to imperfect treatment options. The scenario is complicated by the inability to extrapolate results of cell culture studies and transgenic models to clinical applications which has stagnated the process of improving drug therapy. In this context, the development of biomarkers has been viewed as beneficial to easing various pathological complications. A biomarker is measured and evaluated in order to gauge the physiological process or a pathological progression of a disease and such a marker can also indicate the clinical or pharmacological response to a therapeutic intervention. The development and identification of biomarkers for neurological disorders involves several issues including the complexity of the brain, unresolved discrepant data from experimental and clinical studies, poor clinical diagnostics, lack of functional endpoints, and high cost and complexity of techniques yet research in the area of biomarkers is highly desired. The present work describes existing biomarkers for various neurological disorders, provides support for the idea that biomarker development may ease our understanding underlying pathophysiology of these disorders and help to design and explore therapeutic targets for effective intervention.
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Affiliation(s)
- Vivek Kumar Sharma
- Chitkara College of Pharmacy, Chitkara University, Chandigarh, Punjab, 140401, India.,Government College of Pharmacy, Rohru, Shimla, Himachal Pradesh, 171207, India
| | - Thakur Gurjeet Singh
- Chitkara College of Pharmacy, Chitkara University, Chandigarh, Punjab, 140401, India.
| | - Vineet Mehta
- Government College of Pharmacy, Rohru, Shimla, Himachal Pradesh, 171207, India
| | - Ashi Mannan
- Chitkara College of Pharmacy, Chitkara University, Chandigarh, Punjab, 140401, India
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Venugopal S, Ghulam-Jhelani Z, Ahn IS, Yang X, Wiedau M, Simmons D, Chandler SH. Early deficits in GABA inhibition parallels an increase in L-type Ca 2+ currents in the jaw motor neurons of SOD1 G93A mouse model for ALS. Neurobiol Dis 2023; 177:105992. [PMID: 36623607 DOI: 10.1016/j.nbd.2023.105992] [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: 01/11/2022] [Revised: 12/21/2022] [Accepted: 01/05/2023] [Indexed: 01/09/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) involves protracted pre-symptomatic periods of abnormal motor neuron (MN) excitability occurring in parallel with central and peripheral synaptic perturbations. Focusing on inhibitory control of MNs, we first compared longitudinal changes in pre-synaptic terminal proteins for GABA and glycine neurotransmitters around the soma of retrogradely identified trigeminal jaw closer (JC) MNs and ChAT-labeled midbrain extraocular (EO) MNs in the SOD1G93A mouse model for ALS. Fluorescence immunocytochemistry and confocal imaging were used to quantify GAD67 and GlyT2 synaptic bouton density (SBD) around MN soma at pre-symptomatic ages ∼P12 (postnatal), ∼P50 (adult) and near disease end-stage (∼P135) in SOD1G93A mice and age-matched wild-type (WT) controls. We noted reduced GAD67 innervation in the SOD1G93A trigeminal jaw closer MNs around P12, relative to age-matched WT and no significant difference around P50 and P135. In contrast, both GAD67 and GlyT2 innervation were elevated in the SOD1G93A EO MNs at the pre-symptomatic time points. Considering trigeminal MNs are vulnerable in ALS while EO MNs are spared, we suggest that upregulation of inhibition in the latter might be compensatory. Notable contrast also existed in the innate co-expression patterns of GAD67 and GlyT2 with higher mutual information (co-dependency) in EO MNs compared to JC in both SOD1G93A and WT mice, especially at adult stages (P50 and P135). Around P12 when GAD67 terminals expression was low in the mutant, we further tested for persistent GABA inhibition in those MNs using in vitro patch-clamp electrophysiology. Our results show that SOD1G93A JC MNs have reduced persistent GABA inhibition, relative to WT. Pharmacological blocking of an underlying tonically active GABA conductance using the GABA-α5 subunit inverse agonist, L-655-708, disinhibited WT JC MNs and lowered their recruitment threshold, suggesting its role in the control of intrinsic MN excitability. Quantitative RT-PCR in laser dissected JC MNs further supported a reduction in GABA-α5 subunit mRNA expression in the mutant. In light of our previous report that JC MNs forming putative fast motor units have lower input threshold in the SOD1G93A mice, we suggest that our present result on reduced GABA-α5 tonic inhibition provides for a mechanism contributing to such imbalance. In parallel with reduced GABA inhibition, we noted an increase in voltage-gated L-type Ca2+ currents in the mutant JC MNs around P12. Together these results support that, early modifications in intrinsic properties of vulnerable MNs could be an adaptive response to counter synaptic deficits.
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Affiliation(s)
- Sharmila Venugopal
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Zohal Ghulam-Jhelani
- Undergraduate Interdepartmental Program for Neuroscience, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - In Sook Ahn
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xia Yang
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Martina Wiedau
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Dwayne Simmons
- Department of Biology, Baylor University, Waco, TX 76798, USA
| | - Scott H Chandler
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Wu M, Zhang M, Yin X, Chen K, Hu Z, Zhou Q, Cao X, Chen Z, Liu D. The role of pathological tau in synaptic dysfunction in Alzheimer's diseases. Transl Neurodegener 2021; 10:45. [PMID: 34753506 PMCID: PMC8579533 DOI: 10.1186/s40035-021-00270-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/25/2021] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disease characterized by progressive cognitive decline, accompanied by amyloid-β (Aβ) overload and hyperphosphorylated tau accumulation in the brain. Synaptic dysfunction, an important pathological hallmark in AD, is recognized as the main cause of the cognitive impairments. Accumulating evidence suggests that synaptic dysfunction could be an early pathological event in AD. Pathological tau, which is detached from axonal microtubules and mislocalized into pre- and postsynaptic neuronal compartments, is suggested to induce synaptic dysfunction in several ways, including reducing mobility and release of presynaptic vesicles, decreasing glutamatergic receptors, impairing the maturation of dendritic spines at postsynaptic terminals, disrupting mitochondrial transport and function in synapses, and promoting the phagocytosis of synapses by microglia. Here, we review the current understanding of how pathological tau mediates synaptic dysfunction and contributes to cognitive decline in AD. We propose that elucidating the mechanism by which pathological tau impairs synaptic function is essential for exploring novel therapeutic strategies for AD.
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Affiliation(s)
- Moxin Wu
- Department of Medical Laboratory, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China.,Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
| | - Manqing Zhang
- Medical College of Jiujiang University, Jiujiang, 332000, China
| | - Xiaoping Yin
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China.,Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Kai Chen
- Department of Dermatology, Wuhan No. 1 Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Zhijian Hu
- Department of Medical Laboratory, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Qin Zhou
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
| | - Xianming Cao
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China.,Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Zhiying Chen
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China. .,Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China.
| | - Dan Liu
- Department of Medical Genetics, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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