Neuroscience
Abstract
Protease activated receptor (PAR) 4 (gene: F2RL3) harbors a functional dimorphism, rs773902 A/G (encoding Thr120/Ala120, respectively) and is associated with greater platelet aggregation. The A allele frequency is more common in Black individuals, and Black individuals have a higher incidence of ischemic stroke than White individuals. However, it is not recognized whether the A allele is responsible for worse stroke outcomes. To directly test the in vivo effect of this variant on stroke, we generated mice where F2rl3 was replaced by F2RL3, thereby expressing human PAR4 (hPAR4) with either Thr120 or Ala120. Compared to hPAR4 Ala120 mice, hPAR4 Thr120 mice had worse stroke outcomes, mediated in part by enhanced platelet activation and platelet-neutrophil interactions. Analyses of 7620 Black subjects with 487 incident ischemic strokes demonstrated the AA genotype was a risk for incident ischemic stroke and worse functional outcomes. In humanized mice, ticagrelor with or without aspirin improved stroke outcomes in hPAR4 Ala120 mice, but not in hPAR4 Thr120 mice. P-selectin blockade improved stroke outcomes and reduced platelet-neutrophil interactions in hPAR4 Thr120 mice. Our results may explain some of the racial disparity in stroke and support the need for studies of non-standard anti-platelet therapies for patients expressing PAR4 Thr120.
Authors
Frederik Denorme, Nicole D. Armstrong, Michelle L. Stoller, Irina Portier, Emilia A. Tugolukova, Rikki M. Tanner, Emilie Montenont, Seema Bhatlekar, Mark Cody, John L. Rustad, Abigail Ajanel, Neal D. Tolley, Darian C. Murray, Julie L. Boyle, Marvin T. Nieman, Steven E. McKenzie, Christian Con Yost, Leslie A. Lange, Mary Cushman, Marguerite R. Irvin, Paul F. Bray, Robert A. Campbell
Abstract
The Rad50 interacting protein 1 (Rint1) is a key player in vesicular trafficking between the ER and Golgi apparatus. Biallelic variants in RINT1 cause infantile-onset episodic acute liver failure (ALF). Here, we describe 3 individuals from 2 unrelated families with novel biallelic RINT1 loss-of-function variants who presented with early onset spastic paraplegia, ataxia, optic nerve hypoplasia, and dysmorphic features, broadening the previously described phenotype. Our functional and lipidomic analyses provided evidence that pathogenic RINT1 variants induce defective lipid–droplet biogenesis and profound lipid abnormalities in fibroblasts and plasma that impact both neutral lipid and phospholipid metabolism, including decreased triglycerides and diglycerides, phosphatidylcholine/phosphatidylserine ratios, and inhibited Lands cycle. Further, RINT1 mutations induced intracellular ROS production and reduced ATP synthesis, affecting mitochondria with membrane depolarization, aberrant cristae ultrastructure, and increased fission. Altogether, our results highlighted the pivotal role of RINT1 in lipid metabolism and mitochondria function, with a profound effect in central nervous system development.
Authors
Nathalie Launay, Montserrat Ruiz, Laura Planas-Serra, Edgard Verdura, Agustí Rodríguez-Palmero, Agatha Schlüter, Leire Goicoechea, Cristina Guilera, Josefina Casas, Felix Campelo, Emmanuelle Jouanguy, Jean-Laurent Casanova, Odile Boespflug-Tanguy, Maria Vazquez Cancela, Luis González Gutiérrez-Solana, Carlos Casasnovas, Estela Area-Gomez, Aurora Pujol
Abstract
Mutations in HNRNPH2 cause an X-linked neurodevelopmental disorder with features that include developmental delay, motor function deficits, and seizures. More than 90% of patients with hnRNPH2 have a missense mutation within or adjacent to the nuclear localization signal (NLS) of hnRNPH2. Here, we report that hnRNPH2 NLS mutations caused reduced interaction with the nuclear transport receptor Kapβ2 and resulted in modest cytoplasmic accumulation of hnRNPH2. We generated 2 knockin mouse models with human-equivalent mutations in Hnrnph2 as well as Hnrnph2-KO mice. Knockin mice recapitulated clinical features of the human disorder, including reduced survival in male mice, impaired motor and cognitive functions, and increased susceptibility to audiogenic seizures. In contrast, 2 independent lines of Hnrnph2-KO mice showed no detectable phenotypes. Notably, KO mice had upregulated expression of Hnrnph1, a paralog of Hnrnph2, whereas knockin mice failed to upregulate Hnrnph1. Thus, genetic compensation by Hnrnph1 may counteract the loss of hnRNPH2. These findings suggest that HNRNPH2-related disorder may be driven by a toxic gain of function or a complex loss of HNRNPH2 function with impaired compensation by HNRNPH1. The knockin mice described here are an important resource for preclinical studies to assess the therapeutic benefit of gene replacement or knockdown of mutant hnRNPH2.
Authors
Ane Korff, Xiaojing Yang, Kevin O’Donovan, Abner Gonzalez, Brett J.W. Teubner, Haruko Nakamura, James Messing, Fen Yang, Alexandre F. Carisey, Yong-Dong Wang, Tushar Patni, Heather Sheppard, Stanislav S. Zakharenko, Yuh Min Chook, J. Paul Taylor, Hong Joo Kim
Abstract
Protein aggregation is a hallmark of many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Although mutations in TARDBP, encoding TDP-43, account for less than 1% of all ALS cases, TDP-43-positive aggregates are present in nearly all ALS patients, including patients with sporadic ALS (sALS) or carrying other familial ALS (fALS)-causing mutations. Interestingly, TDP-43 inclusions are also present in subsets of patients with frontotemporal dementia, Alzheimer’s disease, and Parkinson’s disease; therefore, methods of activating intracellular protein quality control machinery capable of clearing toxic cytoplasmic TDP-43 species may alleviate disease-related phenotypes. Here, we identify a novel function of Nemo-like kinase (Nlk) as a negative regulator of lysosome biogenesis. Genetic or pharmacological reduction of Nlk increased lysosome formation and improved clearance of aggregated TDP-43. Furthermore, Nlk reduction ameliorated pathological, behavioral, and lifespan deficits in two distinct mouse models of TDP-43 proteinopathy. Because many toxic proteins can be cleared along the autophagy-lysosome axis, targeted reduction of Nlk represents a potential approach to therapy development for multiple neurodegenerative disorders.
Authors
Leon Tejwani, Youngseob Jung, Hiroshi Kokubu, Sowmithra Sowmithra, Luhan Ni, Changwoo Lee, Benjamin Sanders, Paul J. Lee, Yangfei Xiang, Kimberly Luttik, Armand Soriano, Jennifer Yoon, Junhyun Park, Hannah H. Ro, Hyoungseok Ju, Clara Liao, Sofia Massaro Tieze, Frank Rigo, Paymaan Jafar-Nejad, Janghoo Lim
Abstract
Microglia are the major cell type expressing complement C3a receptor (C3aR) in the brain. Using a knockin mouse line in which a Td-tomato reporter is incorporated into the endogenous C3ar1 locus, we identified 2 major subpopulations of microglia with differential C3aR expression. Expressing the Td-tomato reporter on the APPNL-G-F–knockin (APP-KI) background revealed a significant shift of microglia to a high-C3aR-expressing subpopulation and they were enriched around amyloid β (Aβ) plaques. Transcriptomic analysis of C3aR-positive microglia documented dysfunctional metabolic signatures, including upregulation of hypoxia-inducible factor 1 (HIF-1) signaling and abnormal lipid metabolism in APP-KI mice compared with wild-type controls. Using primary microglial cultures, we found that C3ar1-null microglia had lower HIF-1α expression and were resistant to hypoxia mimetic–induced metabolic changes and lipid droplet accumulation. These were associated with improved receptor recycling and Aβ phagocytosis. Crossing C3ar1-knockout mice with the APP-KI mice showed that C3aR ablation rescued the dysregulated lipid profiles and improved microglial phagocytic and clustering abilities. These were associated with ameliorated Aβ pathology and restored synaptic and cognitive function. Our studies identify a heightened C3aR/HIF-1α signaling axis that influences microglial metabolic and lipid homeostasis in Alzheimer disease, suggesting that targeting this pathway may offer therapeutic benefit.
Authors
Manasee Gedam, Michele M. Comerota, Nicholas E. Propson, Tao Chen, Feng Jin, Meng C. Wang, Hui Zheng
Abstract
Alzheimer’s disease (AD) is the most common cause of dementia. The APOE-ε4 allele of the apolipoprotein E (APOE) gene is the strongest genetic risk factor for late-onset AD. APOE genotype modulates the effect of sleep disruption on AD risk, suggesting a possible link between apoE and sleep in AD pathogenesis which is relatively unexplored. We hypothesized that apoE modifies Aβ deposition and Aβ plaque-associated tau seeding and spreading in the form of neuritic plaque (NP)-tau pathology in response to chronic sleep deprivation (SD) in an apoE isoform-dependent fashion. To test this hypothesis, we used APPPS1 mice expressing human APOE-ε3 or -ε4 with or without AD-tau injection. We found that SD in APPPS1 mice significantly increased Aβ deposition and peri-plaque NP-tau pathology in the presence of APOE4, but not APOE3. SD in APPPS1 mice significantly decreased microglial clustering around plaques and aquaporin-4 (AQP4) polarization around blood vessels in the presence of APOE4 but not APOE3. We also found that sleep deprived APPPS1:E4 mice injected with AD tau had significantly altered sleep behaviors as compared to APPPS1:E3 mice. These findings suggest that APOE-ε4 genotype is a critical modifier in the development of AD pathology in response to SD.
Authors
Chanung Wang, Aishwarya Nambiar, Michael R. Strickland, Choonghee Lee, Samira Parhizkar, Alec C. Moore, Erik S. Musiek, Jason D. Ulrich, David M. Holtzman
Abstract
Although glucose is the basic fuel essential to maintain the viability and functions of all cells, some neurons, namely glucose-inhibited (GI) neurons, paradoxically increase their firing activities when glucose falls and are inhibited by high glucose. The ionic mechanisms mediating electric responses of GI neurons to glucose fluctuations remain unclear. Here we showed that currents mediated by anoctamin 4 (Ano4) channel are only detected in GI neurons in the ventromedial hypothalamic nucleus (VMH) and are functionally required for their activation in response to low glucose. Genetic disruption of the Ano4 gene in VMH neurons reduced blood glucose and impaired counterregulatory responses during hypoglycemia in mice. Activation of VMHAno4 neurons increased food intake and blood glucose, while chronic inhibition of VMHAno4 neurons ameliorated hyperglycemia in a type 1 diabetic mouse model. Finally, we showed that VMHAno4 neurons represent a unique orexigenic VMH population and transmit a positive valence, while stimulation of non-Ano4 neurons in the VMH suppress feeding and transmit a negative valence. Together, our results indicate that the Ano4 channel and VMHAno4 neurons are potential therapeutic targets for human diseases with abnormal feeding behavior or glucose imbalance.
Authors
Longlong Tu, Jonathan C. Bean, Yang He, Hailan Liu, Meng Yu, Hesong Liu, Nan Zhang, Na Yin, Junying Han, Nikolas Anthony Scarcelli, Kristine Marie Conde, Mengjie Wang, Yongxiang Li, Bing Feng, Peiyu Gao, Zhao-Lin Cai, Makoto Fukuda, Mingshan Xue, Qingchun Tong, Yongjie Yang, Lan Liao, Jianming Xu, Chunmei Wang, Yanlin He, Yong Xu
Abstract
Dravet syndrome (DS), an intractable childhood epileptic encephalopathy with a high fatality rate, is typically caused by loss-of-function mutations in one allele of SCN1A, which encodes NaV1.1, a 250-kDa voltage-gated sodium channel. In contrast to other epilepsies, pharmaceutical treatment for DS is limited. Here, we demonstrate that viral vector-mediated delivery of a codon-modified SCN1A open reading frame into the brain improves DS comorbidities in juvenile and adolescent DS mice (Scn1aA1783V/WT). Notably, bilateral vector injections into the hippocampus and/or the thalamus of DS mice increased survival, reduced the occurrence of epileptic spikes, provided protection from thermally-induced seizures, corrected background electrocorticography activity and behavioral deficits, and restored hippocampal inhibition. Together, our results provide a proof-of-concept for the potential of SCN1A delivery as a therapeutic approach for infants and adolescents with DS-associated comorbidities.
Authors
Saja Fadila, Bertrand Beucher, Iria González Dopeso-Reyes, Anat Mavashov, Marina Brusel, Karen Anderson, Caroline Ismeurt, Ethan M. Goldberg, Ana Ricobaraza, Ruben Hernandez-Alcoceba, Eric J. Kremer, Moran Rubinstein
Abstract
Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the gradual loss of midbrain dopaminergic neurons in association with aggregation of α-synuclein. Oxidative damage has been widely implicated in this disease, though the mechanisms involved remain elusive. Here, we demonstrated that preferential accumulation of peroxidized phospholipids and loss of the antioxidant enzyme glutathione peroxidase 4 (GPX4) were responsible for vulnerability of midbrain dopaminergic neurons and progressive motor dysfunctions in a mouse model of PD. We also established a mechanism wherein iron-induced dopamine oxidation modified GPX4, thereby rendering it amenable to degradation via the ubiquitin-proteasome pathway. In conclusion, this study unraveled what we believe to be a novel pathway for dopaminergic neuron degeneration during PD pathogenesis, driven by dopamine-induced loss of antioxidant GPX4 activity.
Authors
Jie Sun, Xiao-Min Lin, Dan-Hua Lu, Meng Wang, Kun Li, Sheng-Rong Li, Zheng-Qiu Li, Cheng-Jun Zhu, Zhi-Min Zhang, Chang-Yu Yan, Ming-Hai Pan, Hai-Biao Gong, Jing-Cheng Feng, Yun-Feng Cao, Feng Huang, Wan-Yang Sun, Hiroshi Kurihara, Yi-Fang Li, Wen-Jun Duan, Gen-Long Jiao, Li Zhang, Rong-Rong He
Abstract
Patients with Autosomal Recessive Microcephaly 15 caused by deficiency in the sodium-dependent lysophosphatidylcholine (LPC) transporter Major Facilitator Superfamily Domain containing 2a (Mfsd2a) present with both microcephaly and hypomyelination, suggesting an important role of LPC uptake by oligodendrocytes in the process of myelination. Here, we demonstrate that Mfsd2a is specifically expressed in oligodendrocyte precursor cells (OPC) and is critical for oligodendrocyte development. Single cell sequencing of the oligodendrocyte lineage revealed that OPCs from OPC-specific Mfsd2a KO mice (2aOKO) underwent precocious differentiation into immature oligodendrocytes (iOLs) and impaired maturation into myelinating oligodendrocytes, correlating with postnatal brain hypomyelination. 2aOKO mice did not exhibit microcephaly, consistent with microcephaly being consequential to absence of LPC uptake at the blood-brain barrier and not from deficiency in OPCs. Lipidomic analysis showed that OPCs and iOLs from 2aOKO mice had significantly decreased phospholipids containing omega-3 fatty acids with an opposite increase in unsaturated fatty acids, that latter being products of de novo synthesis governed by Srebp-1. RNA sequencing indicated activation of the Srebp-1 pathway and defective expression of regulators of oligodendrocyte development. Taken together, these findings indicate that the transport of LPCs by Mfsd2a in OPCs is important for maintaining OPC cell state to regulate postnatal brain myelination.
Authors
Vetrivel Sengottuvel, Monalisa Hota, Jeongah Oh, Dwight L. Galam, Bernice H. Wong, Markus R. Wenk, Sujoy Ghosh, Federico Torta, David L. Silver
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)