Neuroscience
Abstract
The spliceosome is a critical cellular machinery responsible for pre-mRNA splicing, essential for the proper expression of genes. Mutations in its core components are increasingly linked to neurodevelopmental disorders, such as primary microcephaly. Here, we investigated the role of SNW1, a spliceosomal protein, in splicing integrity and neurodevelopment. We identified nine heterozygous mutations in the SNW1 gene in patients presenting with primary microcephaly. These mutations impaired SNW1's interactions with core spliceosomal proteins, leading to defective RNA splicing and reduced protein functionality. Using Drosophila melanogaster and human embryonic stem cell-derived cerebral organoids models, we demonstrated that SNW1 depletion resulted in significant reductions in neural stem cell proliferation and increased apoptosis. RNA-sequencing revealed disrupted alternative splicing, especially skipping exons, and altered expression of neurodevelopment-associated genes (CENPE, MEF2C, and NRXN2). Our findings provide crucial insights into the molecular mechanisms by which SNW1 dysfunction contributes to neurodevelopmental disorders and underscore the importance of proper spliceosome function in brain development.
Authors
Lei Ji, Jin Yan, Nicole A. Losurdo, Hua Wang, Liangjie Liu, Keyi Li, Zhen Liu, Zhenming Guo, Jing Xu, Adriana Bibo, Decheng Ren, Ke Yang, Yingying Luo, Fengping Yang, Gui Wang, Zhenglong Xiang, Yuan Wang, Huaizhe Zhan, Hu Pan, Juanli Hu, Jianmin Zhong, Rami Abou Jamra, Pia Zacher, Luciana Musante, Flavio Faletra, Paola Costa, Caterina Zanus, Nathalie Couque, Lyse Ruaud, Anna Maria Cueto-González, Hector San Nicolas Fernández, Eduardo Tizzano, Núria Martínez Gil, Xiaorong Liu, Weiping Liao, Layal Abi Farraj, Alden Y. Huang, Liying Zhang, Aparna Murali, Esther Schmuel, Christina S. Han, Kayla King, Weiyue Gu, Pengchao Wang, Kai Li, Nichole Link, Guang He, Shan Bian, Xiao Mao
Abstract
Neurofibromatosis type 1 (NF1) is a genetic disorder caused by mutations of the NF1 tumor suppressor gene resulting in the loss of function of neurofibromin, a GTPase-activating protein (GAP) for Ras. While the malignant manifestations of NF1 are associated with loss of heterozygosity of the residual WT allele, the nonmalignant neurodevelopmental sequelae, including autism spectrum disorder (ASD) and/or attention deficit hyperactivity disorder (ADHD) are prevalent morbidities that occur in the setting of neurofibromin haploinsufficiency. We reasoned that augmenting endogenous levels of WT neurofibromin could serve as a potential therapeutic strategy to correct the neurodevelopmental manifestations of NF1. Here, we used a combination of genetic screening and genetically engineered murine models to identify a role for the F-box protein FBXW11 as a regulator of neurofibromin degradation. Disruption of Fbxw11, through germline mutation or targeted genetic manipulation in the nucleus accumbens, increased neurofibromin levels, suppressed Ras-dependent ERK phosphorylation, and corrected social learning deficits and impulsive behaviors in male Nf1+/– mice. Our results demonstrate that preventing the degradation of neurofibromin is a feasible and effective approach to ameliorate the neurodevelopmental phenotypes in a haploinsufficient disease model.
Authors
Su Jung Park, Jodi L. Lukkes, Ka-Kui Chan, Hayley P. Drozd, Callie B. Burgin, Shaomin Qian, Morgan McKenzie Sullivan, Cesar Gabriel Guevara, Nolen Cunningham, Stephanie Arenas, Makenna A. Collins, Jacob Zucker, JinHee Won, Abbi Smith, Li Jiang, Dana K. Mitchell, Steven D. Rhodes, Steven P. Angus, D. Wade Clapp
Abstract
Sustaining the strong rhythmic interactions between cellular adaptations and environmental cues has been posited as essential for preserving the physiological and behavioral alignment of an organism to the proper phase of the daily light/dark (LD) cycle. Here, we demonstrate that mitochondria and synaptic input organization of suprachiasmatic (SCN) vasoactive intestinal peptide–expressing (VIP-expressing) neurons showed circadian rhythmicity. Perturbed mitochondrial dynamics achieved by conditional ablation of the fusogenic protein mitofusin 2 (Mfn2) in VIP neurons caused disrupted circadian oscillation in mitochondria and synapses in SCN VIP neurons, leading to desynchronization of entrainment to the LD cycle in Mfn2-deficient mice that resulted in an advanced phase angle of their locomotor activity onset, alterations in core body temperature, and sleep-wake amount and architecture. Our data provide direct evidence of circadian SCN clock machinery dependence on high-performance, Mfn2-regulated mitochondrial dynamics in VIP neurons for maintaining the coherence in daily biological rhythms of the mammalian organism.
Authors
Milan Stoiljkovic, Jae Eun Song, Hee-kyung Hong, Heiko Endle, Luis Varela, Jonatas Catarino, Xiao-Bing Gao, Zong-Wu Liu, Peter Sotonyi, Sabrina Diano, Jonathan Cedernaes, Joseph T. Bass, Tamas L. Horvath
Abstract
Neuropathic pain is often comorbid with affective disorders. Synaptic plasticity in anterior cingulate cortex (ACC) is assumed to be a crucial interface for pain perception and emotion. Laminin β1 (LAMB1), a key element of extracellular matrix (ECM) in ACC was recently revealed to convey extracellular alterations to intracellular synaptic plasticity and underlie neuropathic pain and aversive emotion. However, it remains elusive what triggers activity-dependent changes of LAMB1 and ECM remodeling after nerve injury. Here, we uncovered a key role of retinoic acid (RA)/RARB signaling in neuropathic pain and associated anxiodepression via regulation of ECM homeostasis. We showed that nerve injury reduced RA level in the serum and ACC in mice and human, which brought about downregulation of its corresponding receptor, RARB. Overexpressing RARB relieved pain hypersensitivity and comorbid anxiodepression, while silencing RARB exacerbated pain sensitivity and induced anxiodepression. Further mechanistic analysis revealed that RARB maintained ECM homeostasis via transcriptional regulation of LAMB1, reversing abnormal synaptic plasticity and eventually improved neuropathic pain and aversive emotion. Taken together with our previous study, we revealed an intracellular-extracellular-intracellular feedforward regulatory network in modulating pain plasticity. Moreover, we identified cingulate RA/RARB signaling as a promising therapeutic target for treatment of neuropathic pain and associated anxiodepression.
Authors
Zhen-Zhen Li, Wan-Neng Liu, Ke-Xin Liu, Zhi-Wei Dou, Rui Zhao, Yun Chen, Meng-Meng Wang, Tao-Zhi Wang, Fei Wang, Wen-Juan Han, Wen-Guang Chu, Xing-Xing Zheng, Rou-Gang Xie, Hua Yuan, Xiao-Fan Jiang, Xiao-Long Sun, Ceng Luo, Shengxi Wu
Abstract
Cytoplasmic TDP43 mislocalization and aggregation are pathological hallmarks of amyotrophic lateral sclerosis (ALS). However, the initial cellular insults that lead to TDP43 mislocalization remain unclear. In this study, we demonstrate that Nemo-like kinase (NLK) — a proline-directed serine/threonine kinase — promotes the mislocalization of TDP43 and other RNA-binding proteins by disrupting nuclear import. NLK levels are selectively elevated in neurons exhibiting TDP43 mislocalization in ALS patient tissues, while genetic reduction of NLK reduces toxicity in human neuron models of ALS. Our findings suggest that NLK is a promising therapeutic target for neurodegenerative diseases.
Authors
Michael E. Bekier II, Emile S. Pinarbasi, Gopinath Krishnan, Jack J. Mesojedec, Madelaine Hurley, Harisankar Harikumar Sheela, Catherine A. Collins, Layla T. Ghaffari, Martina de Majo, Erik M. Ullian, Mark Koontz, Sarah Coleman, Xingli Li, Elizabeth M.H. Tank, Jacob Waksmacki, Fen-Biao Gao, Sami J. Barmada
Abstract
Up to 10% of patients with severe early-onset obesity carry pathogenic variants in known obesity-related genes, mostly affecting the leptin-melanocortin pathway. Studying children with severe obesity from consanguineous populations provides a unique opportunity to uncover novel molecular mechanisms. Using whole-exome sequencing, followed by a rigorous analytical and filtration strategy, we identified three different homozygous missense variants in SREK1 (encoding Splicing Regulatory glutamic acid and lysine rich protein) in Pakistani children with severe obesity, from three unrelated consanguineous pedigrees. The wild type SREK1 gene of human induced pluripotent stem cell (iPSC)-derived hypothalamic neurons was individually replaced by each of the three variants and the impact of these changes on global gene expression was studied. Neurons expressing the two variants in the SREK1 RNA recognition domain p.P95L and p.T194M, but not the C-terminally located p.E601K, had markedly reduced expression of the small nucleolar RNA clusters SNORD115 and SNORD116, deficiency of which has been implicated in Prader-Willi syndrome (PWS). In addition to hyperphagic obesity the carriers of these two variants had other features of PWS, such as neonatal hypotonia. In conclusion, homozygous variants in SREK1 result in a subtype of severe early onset obesity sharing features with PWS.
Authors
Sadia Saeed, Anna-Maria Siegert, YC Loraine Tung, Roohia Khanam, Qasim M. Janjua, Jaida Manzoor, Mehdi Derhourhi, Bénédicte Toussaint, Brian Y. H. Lam, Sherine Awad, Emmanuel Vaillant, Emmanuel Buse Falay, Souhila Amanzougarene, Hina Ayesha, Waqas Imran Khan, Nosheen Ramzan, Vladimir Saudek, Stephen O'Rahilly, Anthony P. Goldstone, Muhammad Arslan, Amélie Bonnefond, Philippe Froguel, Giles S.H. Yeo
Abstract
Mucopolysaccharidoses (MPS) are lysosomal storage diseases caused by defects in catabolism of glycosaminoglycans. MPS I, II, III and VII, associated with lysosomal accumulation of heparan sulphate (HS), manifest with neurological deterioration and currently lack effective treatments. We report that neuraminidase 1 (NEU1) activity is drastically reduced in brain tissues of neurological MPS patients and mouse models but not in neurological lysosomal disorders without HS storage. Accumulated HS disrupts the lysosomal multienzyme complex of NEU1 with cathepsin A (CTSA), β-galactosidase (GLB1) and glucosamine-6-sulfate sulfatase (GALNS) leading to NEU1 deficiency and partial GLB1 and GALNS deficiencies in cortical tissues and iPSC-derived cortical neurons of neurological MPS patients. Increased sialylation of N-linked glycans in brains of MPS patients and mice implicated insufficient processing of sialylated glycans, except for polysialic acid. Correction of NEU1 activity in MPS IIIC mice by lentiviral gene transfer ameliorated previously identified hallmarks of the disease, including memory impairment, behavioural traits, and reduced levels of excitatory synapse markers VGLUT1 and PSD95. Overexpression of NEU1 also restored levels of VGLUT1/PSD95-positive puncta in cortical iPSC-derived MPS IIIA neurons. Our results demonstrate that HS-induced secondary NEU1 deficiency and aberrant sialylation of brain glycoproteins constitute what we believe to be a novel pathological pathway in neurological MPS spectrum crucially contributing to CNS pathology.
Authors
TianMeng Xu, Rachel Heon-Roberts, Travis Moore, Patricia Dubot, Xuefang Pan, Tianlin Guo, Christopher W. Cairo, Rebecca J. Holley, Brian Bigger, Thomas M. Durcan, Thierry Levade, Jerôme Ausseil, Bénédicte Amilhon, Alexei Gorelik, Bhushan Nagar, Shaukat Khan, Shunji Tomatsu, Luisa Sturiale, Angelo Palmigiano, Iris Röckle, Hauke Thiesler, Herbert Hildebrandt, Domenico Garozzo, Alexey V. Pshezhetsky
Abstract
Metachromatic leukodystrophy (MLD) is an autosomal recessive neurodegenerative disorder caused by mutations in the arylsulfatase A (ARSA) gene, resulting in lower sulfatase activity and the toxic accumulation of sulfatides in the central and peripheral nervous system. Children account for 70% of cases and become progressively disabled with death occurring within 10 years of disease onset. Gene therapy approaches to restore ARSA expression via adeno-associated viral vectors (AAV) have been promising but hampered by limited brain biodistribution. We report the development of an engineered capsid AAV.GMU01, demonstrating superior biodistribution and transgene expression in the central nervous system of non-human primates (NHPs). Next, we show that AAV.GMU01-ARSA treated MLD mice exhibit persistent, normal levels of sulfatase activity and a concomitant reduction in toxic sulfatides. Treated mice also show a reduction in MLD-associated pathology and auditory dysfunction. Lastly, we demonstrate that treatment with AAV.GMU01-ARSA in NHPs is well-tolerated and results in potentially therapeutic ARSA expression in the brain. In summary, we propose AAV.GMU01-ARSA mediated gene replacement as a clinically viable approach to achieve broad and therapeutic levels of ARSA.
Authors
Shyam Ramachandran, Jeffery Ardinger, Jie Bu, MiAngela Ramos, Lilu Guo, Dhiman Ghosh, Mahmud Hossain, Shih-Ching Chou, Yao Chen, Erik Wischhof, Swathi Ayloo, Roger Trullo, Yuxia Luo, Jessica M. Hogestyn, Daniel M. DuBreuil, Emily Crosier, Johanna G. Flyer-Adams, Amy M. Richards, Michael Tsabar, Giorgio Gaglia, Shelley Nass, Bindu Nambiar, Denise Woodcock, Catherine O'Riordan, Qi Tang, Bradford Elmer, Bailin Zhang, Martin Goulet, Christian Mueller
Abstract
Authors
Rudy J. Castellani, Hinda Najem, Amy B. Heimberger, Pouya Jamshidi
Abstract
Late-onset Tay-Sachs (LOTS) disease is a lysosomal storage disorder most commonly caused by a point mutation (c.805G>A) in the HEXA gene encoding the α-subunit of the lysosomal enzyme β-hexosaminidase A. LOTS manifests as a range of gradually worsening neurological symptoms beginning in young adulthood. Here, we explored the efficacy of an adenine base editor (ABE) programmed with a small guide RNA (sgRNA) to correct the HEXA c.805G>A mutation. Base editing in LOTS patient fibroblasts successfully converted the pathogenic HEXA c.805A to G and partially restored β-hexosaminidase activity, with minimal genome-wide off-target editing. We generated a LOTS mouse model in which the mice exhibited decreased β-hexosaminidase activity, accumulation of GM2 ganglioside in the brain, progressive neurological manifestations, and reduced lifespan. Treatment of LOTS mice with the neurotropic virus AAV-PHP.eB carrying the ABE and an sgRNA targeting the LOTS point mutation partially corrected the c.805G>A mutation in the CNS, significantly increased brain β-hexosaminidase activity, and substantially reduced GM2 ganglioside accumulation in the brain. Moreover, the therapy delayed symptom onset and significantly extended median lifespan. These findings highlight the potential of base editing as an effective treatment for LOTS and its broader applicability to other lysosomal storage disorders.
Authors
Maria L Allende, Mari Kono, Y. Terry Lee, Samantha M. Olmsted, Vienna Huso, Jenna Y. Bakir, Florencia Pratto, Cuiling Li, Colleen Byrnes, Galina Tuymetova, Hongling Zhu, Cynthia J. Tifft, Richard L. Proia
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)