Neuroscience
Abstract
Neurofibromatosis type 1 (NF1) is a common tumor predisposition syndrome, caused by NF1 gene mutation, in which affected patients develop Schwann cell lineage peripheral nerve sheath tumors (neurofibromas). To investigate human neurofibroma pathogenesis, we differentiated a series of isogenic patient-specific NF1-mutant human induced-pluripotent stem cells (hiPSCs) into Schwannian lineage cells (SLCs). We found that while wild-type and heterozygous NF1-mutant hiPSC-SLCs did not form tumors following mouse sciatic nerve implantation, NF1-null SLCs formed bona fide neurofibromas with high levels of SOX10 expression. To confirm that SOX10+ SLCs contain the cells of origin for neurofibromas, both Nf1 alleles were inactivated in mouse Sox10+ cells, leading to classic nodular cutaneous and plexiform neurofibroma formation that completely recapitulate their human counterparts. Moreover, we discovered that NF1 loss impaired Schwann cell differentiation by inducing a persistent stem-like state to expand the pool of progenitors required to initiate tumor formation, indicating that in addition to regulating MAPK-mediated cell growth, NF1 loss also alters Schwann cell differentiation to promote neurofibroma development. Taken together, we established complementary humanized neurofibroma explant and first-in-kind mouse genetically engineered nodular cutaneous neurofibroma models that delineate neurofibroma pathogenesis amenable to future therapeutic target discovery and evaluation.
Authors
Juan Mo, Corina Anastasaki, Zhiguo Chen, Tracey Shipman, Jason B. Papke, Kevin Y. Yin, David H. Gutmann, Lu Q. Le
Abstract
The α6β4 nicotinic acetylcholine receptor (nAChR) is enriched in dorsal root ganglia neurons and is an attractive non-opioid therapeutic target for pain. However, difficulty expressing human α6β4 receptors in recombinant systems has precluded drug discovery. Here, genome-wide screening identified accessory proteins that enable reconstitution of human α6β4 nAChRs. BARP, an auxiliary subunit of voltage-dependent calcium channels, promoted α6β4 surface expression while IRE1α, an unfolded protein response sensor, enhanced α6β4 receptor assembly. Effects on α6β4 involve BARP’s N-terminal region and IRE1α’s splicing of XBP1 mRNA. Furthermore, clinical efficacy of nicotinic agents in relieving neuropathic pain best correlated with their activity on α6β4. Finally, BARP-knockout, but not NACHO-knockout mice lacked nicotine-induced antiallodynia, highlighting the functional importance of α6β4 in pain. These results identify roles for IRE1α and BARP in neurotransmitter receptor assembly and unlock drug discovery for the previously elusive α6β4 receptor.
Authors
Daniel Knowland, Shenyan Gu, William A. Eckert III, G. Brent Dawe, Jose A. Matta, James Limberis, Alan D. Wickenden, Anindya Bhattacharya, David S. Bredt
Abstract
Edema is an important target for clinical intervention after traumatic brain injury (TBI). We used in vivo cellular resolution imaging and electrophysiological recording to examine the ionic mechanisms underlying neuronal edema and their effects on neuronal and network excitability after controlled cortical impact (CCI) in mice. Unexpectedly, we found that neuronal edema 48 hours after CCI was associated with reduced cellular and network excitability, concurrent with an increase in the expression ratio of the cation-chloride cotransporters (CCCs) NKCC1 and KCC2. Treatment with the CCC blocker bumetanide prevented neuronal swelling via a reversal in the NKCC1/KCC2 expression ratio, identifying altered chloride flux as the mechanism of neuronal edema. Importantly, bumetanide treatment was associated with increased neuronal and network excitability after injury, including increased susceptibility to spreading depolarizations (SDs) and seizures, known agents of clinical worsening after TBI. Treatment with mannitol, a first-line edema treatment in clinical practice, was also associated with increased susceptibility to SDs and seizures after CCI, showing that neuronal volume reduction, regardless of mechanism, was associated with an excitability increase. Finally, we observed an increase in excitability when neuronal edema normalized by 1 week after CCI. We conclude that neuronal swelling may exert protective effects against damaging excitability in the aftermath of TBI and that treatment of edema has the potential to reverse these effects.
Authors
Punam A. Sawant-Pokam, Tyler J. Vail, Cameron S. Metcalf, Jamie L. Maguire, Thomas O. McKean, Nick O. McKean, K.C. Brennan
Haploinsufficiency of immune checkpoint receptor CTLA4 induces a distinct neuroinflammatory disorder
Abstract
BACKGROUND Cytotoxic T lymphocyte antigen 4 (CTLA4) is essential for immune homeostasis. Genetic mutations causing haploinsufficiency (CTLA4h) lead to a phenotypically heterogenous, immune-mediated disease that can include neuroinflammation. The neurological manifestations of CTLA4h are poorly characterized.METHODS We performed an observational natural history study of 50 patients with CTLA4h who were followed at the NIH. We analyzed clinical, radiological, immunological, and histopathological data.RESULTS Evidence for neuroinflammation was observed in 32% (n = 16 of 50) of patients in this cohort by magnetic resonance imaging (MRI) and/or by cerebrospinal fluid analysis. Clinical symptoms were commonly absent or mild in severity, with headaches as the leading complaint (n = 13 of 16). The most striking findings were relapsing, large, contrast-enhancing focal lesions in the brain and spinal cord observed on MRI. We detected inflammation in the cerebrospinal fluid and leptomeninges before the parenchyma. Brain biopsies of inflammatory lesions from 10 patients showed perivascular and intraparenchymal mixed cellular infiltrates with little accompanying demyelination or neuronal injury.CONCLUSIONS Neuroinflammation due to CTLA4h is mediated primarily by an infiltrative process with a distinct and striking dissociation between clinical symptoms and radiological findings in the majority of patients.FUNDING NIAID, NIH, Division of Intramural Research, NINDS, NIH, Division of Intramural Research, and the National Multiple Sclerosis Society–American Brain Foundation.TRIAL REGISTRATION ClinicalTrials.gov NCT00001355.
Authors
Matthew K. Schindler, Stefania Pittaluga, Yoshimi Enose-Akahata, Helen C. Su, V. Koneti Rao, Amy Rump, Steven Jacobson, Irene Cortese, Daniel S. Reich, Gulbu Uzel
Abstract
Postnatal failure of oligodendrocyte maturation has been proposed as a cellular mechanism of diffuse white matter injury (WMI) in premature infants. However, the molecular mechanisms for oligodendrocyte maturational failure remain unclear. In neonatal mice and cultured differentiating oligodendrocytes, sublethal intermittent hypoxic (IH) stress activated cyclophilin D–dependent mitochondrial proton leak and uncoupled mitochondrial respiration, leading to transient bioenergetic stress. This was associated with development of diffuse WMI: poor oligodendrocyte maturation, diffuse axonal hypomyelination, and permanent sensorimotor deficit. In normoxic mice and oligodendrocytes, exposure to a mitochondrial uncoupler recapitulated the phenotype of WMI, supporting the detrimental role of mitochondrial uncoupling in the pathogenesis of WMI. Compared with WT mice, cyclophilin D–knockout littermates did not develop bioenergetic stress in response to IH challenge and fully preserved oligodendrocyte maturation, axonal myelination, and neurofunction. Our study identified the cyclophilin D–dependent mitochondrial proton leak and uncoupling as a potentially novel subcellular mechanism for the maturational failure of oligodendrocytes and offers a potential therapeutic target for prevention of diffuse WMI in premature infants experiencing chronic IH stress.
Authors
Zoya Niatsetskaya, Sergey Sosunov, Anna Stepanova, James Goldman, Alexander Galkin, Maria Neginskaya, Evgeny Pavlov, Vadim Ten
Abstract
Homeostasis of bone metabolism is regulated by the central nervous system and mood disorders such as anxiety are associated with bone metabolism abnormalities, yet our understanding of the central neural circuits regulating bone metabolism is limited. Here, we demonstrate that chronic stress in crewmembers resulted in decreased bone density and elevated anxiety in an isolated habitat mimicking a space station. We then used a mouse model to demonstrate that GABAergic neural circuitry in the ventromedial hypothalamus (VMH) mediates chronic stress-induced bone loss. We show that GABAergic inputs in the VMHdm arise from a specific group of somatostatin neurons in the posterior region of bed nucleus of the stria terminalis (BNST), which is indispensable for stress-induced bone loss and is able to trigger bone loss in the absence of stressors. In addition, the sympathetic system and glutamatergic neurons in nucleus tractus solitaries (NTS) were employed to regulate stress-induced bone loss. Our study has therefore identified the central neural mechanism by which chronic stress induced mood disorders, such as anxiety, influence bone metabolism.
Authors
Fan Yang, Yunhui Liu, Shanping Chen, Zhongquan Dai, Dazhi Yang, Dashuang Gao, Jie Shao, Yuyao Wang, Ting Wang, Zhijian Zhang, Lu Zhang, William W. Lu, Yinghui Li, Liping Wang
Abstract
Astrocytes play multiple functions in the brain, including blood vessel (BV) homeostasis and function. However, the underlying mechanisms remain elusive. Here, we provide evidence for astrocytic neogenin (NEO1), a member of deleted in colorectal cancer (DCC) family netrin receptors, to be involved in this event. Mice with Neo1 depletion in astrocytes exhibited clustered astrocyte distribution and increased BVs in their cortex. These BVs were leaky with reduced blood flow, disrupted basement membranes (vBMs), decreased pericytes, impaired endothelial cell (EC) barrier, and elevated tip EC proliferation. Increased proliferation was also detected in cultured ECs exposed to the conditional medium (CM) of NEO1 depleted astrocytes. Further screening for angiogenetic factors in the CM identifies netrin-1 (NTN1), whose expression was decreased in NEO1 depleted cortical astrocytes. Adding NTN1 into the CM of NEO1 depleted astrocytes attenuated EC proliferation. Expressing NTN1 in NEO1 mutant cortical astrocytes ameliorated phenotypes in blood–brain barrier (BBB), EC, and astrocyte distribution. NTN1 depletion in astrocytes resulted in similar BV/BBB deficits in the cortex as those of Neo1 mutant mice. In aggregates, these results uncovered an unrecognized pathway, astrocytic NEO1 to NTN1, not only regulating astrocyte distribution, but also promoting cortical BV homeostasis and function.
Authors
Ling-ling Yao, Jin-xia Hu, Qiang Li, Daehoon Lee, Xiao Ren, Jun-shi Zhang, Dong Sun, Hong-sheng Zhang, Yong-gang Wang, Lin Mei, Wen-Cheng Xiong
Abstract
The dorsal medial prefrontal cortex (dmPFC) has been recognized as a key cortical area for nociceptive modulation. However, the underlying neural pathway and the function of specific cell types remain largely unclear. Here, we showed that lesions of the dmPFC induced an algesic and anxious state. By using multiple tracing methods including rabies-based transsynaptic tracing method, an excitatory descending neural pathway from the dmPFC to the ventrolateral periaqueductal gray (vlPAG) was outlined. Specific activation of the dmPFC-vlPAG neural pathway by an optogenetic manipulation, produced analgesic and anxiolytic effects in a chronic pain mice model. Inhibitory neurons in the dmPFC were specifically activated by using a chemogenetic approach, which logically produced an algesic and anxious state under both normal and chronic pain conditions. Antagonists of GABAAR or mGluR1 were applied to the dmPFC, which produced analgesic and anxiolytic effects. In summary, the present results suggest that the dmPFC-vlPAG neural pathway might participate in the maintenance of pain thresholds and anxiolytic behaviors under normal conditions, while silencing or suppressing the dmPFC-vlPAG pathway might be involved in the initial stages and maintenance of chronic pain and the emergence of anxiety-like behaviors.
Authors
Jun-Bin Yin, Shao-Hua Liang, Fei Li, Wen-Jun Zhao, Yang Bai, Yi Sun, Zhen-Yu Wu, Tan Ding, Yan Sun, Hai-Xia Liu, Ya-Cheng Lu, Ting Zhang, Jing Huang, Tao Chen, Hui Li, Zhou-Feng Chen, Jing Cao, Rui Ren, Ya-Nan Peng, Juan Yang, Wei-Dong Zang, Xiang Li, Yu-Lin Dong, Yun-Qing Li
Abstract
BACKGROUND Although mania is characteristic of bipolar disorder, it can also occur following focal brain damage. Such cases may provide unique insight into brain regions responsible for mania symptoms and identify therapeutic targets.METHODS Lesion locations associated with mania were identified using a systematic literature search (n = 41) and mapped onto a common brain atlas. The network of brain regions functionally connected to each lesion location was computed using normative human connectome data (resting-state functional MRI, n = 1000) and contrasted with those obtained from lesion locations not associated with mania (n = 79). Reproducibility was assessed using independent cohorts of mania lesions derived from clinical chart review (n = 15) and of control lesions (n = 490). Results were compared with brain stimulation sites previously reported to induce or relieve mania symptoms.RESULTS Lesion locations associated with mania were heterogeneous and no single brain region was lesioned in all, or even most, cases. However, these lesion locations showed a unique pattern of functional connectivity to the right orbitofrontal cortex, right inferior temporal gyrus, and right frontal pole. This connectivity profile was reproducible across independent lesion cohorts and aligned with the effects of therapeutic brain stimulation on mania symptoms.CONCLUSIONS Brain lesions associated with mania are characterized by a specific pattern of brain connectivity that lends insight into localization of mania symptoms and potential therapeutic targets.FUNDING Fundação para a Ciência e Tecnologia (FCT), Harvard Medical School DuPont-Warren Fellowship, Portuguese national funds from FCT and Fundo Europeu de Desenvolvimento Regional, Child Neurology Foundation Shields Research, Sidney R. Baer, Jr. Foundation, Nancy Lurie Marks Foundation, Mather’s Foundation, and the NIH.
Authors
Gonçalo Cotovio, Daniel Talmasov, J. Bernardo Barahona-Corrêa, Joey Hsu, Suhan Senova, Ricardo Ribeiro, Louis Soussand, Ana Velosa, Vera Cruz e Silva, Natalia Rost, Ona Wu, Alexander L. Cohen, Albino J. Oliveira-Maia, Michael D. Fox
Abstract
No treatment for frontotemporal dementia (FTD), the second most common early-onset dementia, is available but therapeutics are being investigated to target the two main proteins associated with FTD pathological subtypes: TDP-43 (FTLD-TDP) and tau (FTLD-tau). Testing potential therapies in clinical trials is hamstrung by our inability to distinguish between patients with FTLD-TDP and FTLD-tau. Therefore, we evaluated truncated stathmin-2 (STMN2) as a proxy of TDP-43 pathology, given reports that TDP-43 dysfunction causes truncated STMN2 accumulation. Truncated STMN2 accumulated in human iPSC-derived neurons depleted of TDP-43, but not in those with pathogenic TARDBP mutations in the absence of TDP-43 aggregation or loss of nuclear protein. In RNA-seq analyses of human brain samples from the NYGC ALS cohort, truncated STMN2 RNA was confined to tissues and disease sub-types marked by TDP-43 inclusions. Lastly, we validated that truncated STMN2 RNA is elevated in the frontal cortex of a cohort of FTLD-TDP cases but not in controls or cases with progressive supranuclear palsy (PSP), a type of FTLD-tau. Further, in FTLD-TDP, we observed significant associations of truncated STMN2 RNA with phosphorylated TDP-43 levels and an earlier age of disease onset. Overall, our data uncovered truncated STMN2 as a marker for TDP-43 dysfunction in FTD.
Authors
Mercedes Prudencio, Jack Humphrey, Sarah Pickles, Anna-Leigh Brown, Sarah E. Hill, Jennifer Kachergus, Ji Shi, Michael Heckman, Matthew Spiegel, Casey Cook, Yuping Song, Mei Yue, Lillian Daughrity, Yari Carlomagno, Karen Jansen-West, Cristhoper Fernandez De Castro, Michael DeTure, Shunsuke Koga, Ying-Chih Wang, Prasanth Sivakumar, Cristian Bodo, Ana Candalija, Kevin Talbot, Bhuvaneish T. Selvaraj, Karen Burr, Siddharthan Chandran, Jia Newcombe, Tammaryn Lashley, Isabel Hubbard, Demetra Catalano, Duyang Kim, Nadia Propp, Samantha Fennessey, Delphine Fagegaltier, Hemali Phatnani, Maria Secrier, Elizabeth M.C. Fisher, Björn Oskarsson, Marka van Blitterswijk, Rosa Rademakers, Neill R. Graff-Radford, Bradley Boeve, David S. Knopman, Ronald Petersen, Keith Josephs, E. Aubrey Thompson, Towfique Raj, Michael E. Ward, Dennis Dickson, Tania F. Gendron, Pietro Fratta, Leonard Petrucelli
Copyright © 2020 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)