Altered Forebrain Functional Connectivity and Neurotransmission in a Kinase-Inactive Met Mouse Model of Autism

MET, the gene encoding the tyrosine kinase receptor for hepatocyte growth factor, is a susceptibility gene for autism spectrum disorder (ASD). Genetically altered mice with a kinase-inactive Met offer a potential model for understanding neural circuit organization changes in autism. Here, we focus on the somatosensory thalamocortical circuitry because distinct somatosensory sensitivity phenotypes accompany ASD, and this system plays a major role in sensorimotor and social behaviors in mice. We employed resting-state functional magnetic resonance imaging and in vivo high-resolution proton MR spectroscopy to examine neuronal connectivity and neurotransmission of wild-type, heterozygous Met–Emx1, and fully inactive homozygous Met–Emx1 mice. Met–Emx1 brains showed impaired maturation of large-scale somatosensory network connectivity when compared with wild-type controls. Significant sex × genotype interaction in both network features and glutamate/gamma-aminobutyric acid (GABA) balance was observed. Female Met–Emx1 brains showed significant connectivity and glutamate/GABA balance changes in the somatosensory thalamocortical system when compared with wild-type brains. The glutamate/GABA ratio in the thalamus was correlated with the connectivity between the somatosensory cortex and the thalamus in heterozygous Met–Emx1 female brains. The findings support the hypothesis that aberrant functioning of the somatosensory thalamocortical system is at the core of the conspicuous somatosensory behavioral phenotypes observed in Met–Emx1 mice.

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SUN-260 Dual Role of Carboxypeptidase E in Prohormone Processing and a Novel Neurotrophic Factor Mediating Neuroprotection and Cognitive Functions in Hippocampal CA3 Neurons in Mice

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.100 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Lan Xiao ◽

Vinay Sharma ◽

Leila Toulabi ◽

Xuyu Yang ◽

Cheol Lee ◽

...

Keyword(s):

Neurotrophic Factor ◽

Neuronal Degeneration ◽

Tyrosine Kinase Receptor ◽

Wild Type ◽

Prohormone Processing ◽

Hippocampal Ca3 ◽

Ca3 Neurons ◽

The Brain

Abstract Stress causes release of glucocorticoids from the adrenals which then circulate to the brain. High concentrations glucocorticoid from chronic severe stress results in pathophysiology in the brain, including neuronal degeneration, cell death and cognitive dysfunction, leading to diseases such as Alzheimer Disease and Major Depressive Disorders. Neurotrophic/growth factors such as BDNF, NGF and NT3 have been linked to these pathological conditions. Carboxypeptidase E (CPE), a proneuropeptide/prohormone processing enzyme, also named neurotrophic factor-α1(NFα1) is highly expressed in the stress-vulnerable hippocampal CA3 neurons, and was shown to have neuroprotective activity from in vitro studies. Here we investigated if CPE-NFα1 functions in vivo, independent of its enzymatic activity, and the mechanism underlying its action. We generated knock-in mice expressing a non-enzymatic form of CPE, CPE-E342Q, but not wild-type CPE. The CPE-E342Q mice showed significantly decreased neuropeptide content and exhibited obesity, diabetes and infertility due to lack of prohormone processing activity, similar to CPE-KO mice. However, they showed no hippocampal CA3 degeneration, exhibited neurogenesis in the dentate gyrus, and displayed normal spatial learning and memory, similar to CPE wild-type mice, after weaning stress; unlike CPE-KO mice which showed hippocampal CA3 neuronal degeneration and cognitive deficits. Binding studies showed that radiolabeled CPE bound hippocampal cell membrane specifically, in a saturable manner. Binding of CPE and CPE-E342Q to hippocampal neurons activated Erk signaling and pre-treatment with either of these proteins protected neurons against H2O2- or glutamate-induced neurotoxcity by increasing BCL2 expression. In vitro and in vivo inhibitor studies demonstrated that this neuroprotective effect was independent of tyrosine kinase receptor signaling. Taken together, the data provide evidence that CPE-NFα1 is a unique neurotrophic factor which acts through a non-tyrosine kinase receptor to activate Erk-BCL2 signaling to protect hippocampal CA3 neurons against stress-induced neurodegeneration and maintaining normal cognitive functions in mice.

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Repair of the UL21 Locus in Pseudorabies Virus Bartha Enhances the Kinetics of Retrograde, Transneuronal Infection In Vitro and In Vivo

Journal of Virology ◽

10.1128/jvi.02102-08 ◽

2008 ◽

Vol 83 (3) ◽

pp. 1173-1183 ◽

Cited By ~ 28

Author(s):

D. Curanović ◽

M. G. Lyman ◽

C. Bou-Abboud ◽

J. P. Card ◽

L. W. Enquist

Keyword(s):

Pseudorabies Virus ◽

Particle Production ◽

Neural Circuit ◽

Neuronal Cultures ◽

Wild Type ◽

Infectious Particle ◽

Viral Spread ◽

Kinetics Of

ABSTRACT The attenuated pseudorabies virus (PRV) strain Bartha contains several characterized mutations that affect its virulence and ability to spread through neural circuits. This strain contains a small genomic deletion that abrogates anterograde spread and is widely used as a retrograde-restricted neural circuit tracer. Previous studies showed that the retrograde-directed spread of PRV Bartha is slower than that of wild-type PRV. We used compartmented neuronal cultures to characterize the retrograde defect and identify the genetic basis of the phenotype. PRV Bartha is not impaired in retrograde axonal transport, but transneuronal spread among neurons is diminished. Repair of the UL21 locus with wild-type sequence restored efficient transneuronal spread both in vitro and in vivo. It is likely that mutations in the Bartha UL21 gene confer defects that affect infectious particle production, causing a delay in spread to presynaptic neurons and amplification of infection. These events manifest as slower kinetics of retrograde viral spread in a neural circuit.

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Identification of an octamer element required for in vivo expression of the TIE1 gene in endothelial cells

Biochemical Journal ◽

10.1042/bj3600023 ◽

2001 ◽

Vol 360 (1) ◽

pp. 23-29 ◽

Cited By ~ 5

Author(s):

Stephane C. BOUTET ◽

Thomas QUERTERMOUS ◽

Bahaa M. FADEL

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Molecular Mechanisms ◽

Vascular Development ◽

Common Mechanism ◽

Tyrosine Kinase Receptor ◽

Wild Type ◽

Binding Studies ◽

In Vivo Expression

TIE1, an endothelial-cell-specific tyrosine kinase receptor, is required for the survival and growth of microvascular endothelial cells during the capillary sprouting phase of vascular development. To investigate the molecular mechanisms that regulate the expression of TIE1 in the endothelium, we analysed transgenic mouse embryos carrying wild-type or mutant TIE1 promoter/LacZ constructs. Our data indicate that an upstream DNA octamer element (5′-ATGCAAAT-3′) is required for the in vivo expression of TIE1 in embryonic endothelial cells. Transgenic embryos carrying the wild-type TIE1 promoter (−466 to +78bp) fused to LacZ and spanning the octamer element demonstrate endothelial-cell-specific expression of the reporter transgene. Point mutations introduced within the octamer element result in a significant decrease of endothelial LacZ expression, suggesting that the octamer site functions as a positive regulator for TIE1 gene expression in endothelial cells. DNA–protein binding studies show that the octamer element exhibits an endothelial-cell-specific pattern of binding via interaction with endothelial-cell-restricted factor(s). Our findings suggest an important role for the octamer element in regulating the expression of the TIE1 receptor in the embryonic endothelium and suggest a common mechanism for the regulation of the angiogenic and cell-specific TIE1 and TIE2 genes during vascular development.

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Melanocyte development in vivo and in neural crest cell cultures: crucial dependence on the Mitf basic-helix-loop-helix-zipper transcription factor

Development ◽

10.1242/dev.124.12.2377 ◽

1997 ◽

Vol 124 (12) ◽

pp. 2377-2386 ◽

Cited By ~ 10

Author(s):

K. Opdecamp ◽

A. Nakayama ◽

M.T. Nguyen ◽

C.A. Hodgkinson ◽

W.J. Pavan ◽

...

Keyword(s):

Neural Crest ◽

Cell Cultures ◽

Neural Crest Cell ◽

Tyrosine Kinase Receptor ◽

Wild Type ◽

Helix Loop Helix ◽

Migration Pathway ◽

Endothelin 3 ◽

Crest Cell

The more than 20 different Mitf mutations in the mouse are all associated with deficiencies in neural crest-derived melanocytes that range from minor functional disturbances with some alleles to complete absence of mature melanocytes with others. In the trunk region of wild-type embryos, Mitf-expressing cells that coexpressed the melanoblast marker Dct and the tyrosine kinase receptor Kit were found in the dorsolateral neural crest migration pathway. In contrast, in embryos homozygous for an Mitf allele encoding a non-functional Mitf protein, Mitf-expressing cells were extremely rare, no Dct expression was ever found, and the number of Kit-expressing cells was much reduced. Wild-type neural crest cell cultures rapidly gave rise to cells that expressed Mitf and coexpressed Kit and Dct. With time in culture, Kit expression was increased, and pigmented, dendritic cells developed. Addition of the Kit ligand Mgf or endothelin 3 or a combination of these factors all rapidly increased the number of Dct-positive cells. Cultures from Mitf mutant embryos initially displayed Mitf-positive cells similar in numbers and Kit-expression as did wild-type cultures. However, Kit expression did not increase with time in culture and the mutant cells never responded to Mgf or endothelin 3, did not express Dct, and never showed pigment. In fact, even Mitf expression was rapidly lost. The results suggest that Mitf first plays a role in promoting the transition of precursor cells to melanoblasts and subsequently, by influencing Kit expression, melanoblast survival.

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Kirrel3-mediated synapse formation is attenuated by disease-associated missense variants

10.1101/2019.12.30.891085 ◽

2019 ◽

Author(s):

Matthew R. Taylor ◽

E. Anne Martin ◽

Brooke Sinnen ◽

Rajdeep Trilokekar ◽

Emmanuelle Ranza ◽

...

Keyword(s):

Autism Spectrum Disorder ◽

Intellectual Disability ◽

Synapse Formation ◽

Autism Spectrum ◽

Spectrum Disorder ◽

Cellular Interactions ◽

Loss Of Function ◽

Wild Type ◽

Missense Variants

ABSTRACTMissense variants in Kirrel3 are repeatedly identified as risk factors for autism spectrum disorder and intellectual disability but it has not been reported if or how these variants disrupt Kirrel3 function. Previously, we studied Kirrel3 loss-of-function using knockout mice and showed that Kirrel3 is a synaptic adhesion molecule necessary to form one specific type of hippocampal synapse in vivo. Here, we developed a new gain-of-function assay for Kirrel3 and find that wild-type Kirrel3 induces synapse formation selectively between Kirrel3-expressing cells via homophilic, trans-cellular binding. We tested six disease-associated Kirrel3 missense variants and find that five attenuate this synaptogenic function. All variants tested traffic to the cell surface and localize to synapses similar to wild-type Kirrel3. Two tested variants lack homophilic trans-cellular binding, which likely accounts for their reduced synaptogenic function. Interestingly, we also identified variants that bind in trans but cannot induce synapses, indicating Kirrel3 trans-cellular binding is necessary but not sufficient for its synaptogenic function. Collectively, these results suggest Kirrel3 functions as a synaptogenic, cell-recognition molecule, and this function is attenuated by missense variants associated with autism spectrum disorder and intellectual disability. Thus, we provide critical insight to Kirrel3 function in typical brain development and the consequences of missense variants associated with autism spectrum disorder and intellectual disability.SIGNIFICANCE STATEMENTHere, we advance our understanding of mechanisms mediating target-specific synapse formation by providing evidence that Kirrel3 trans-cellular interactions mediate contact recognition and signaling to promote synapse development. Moreover, this is the first study to test the effects of disease-associated Kirrel3 missense variants on synapse formation, and thereby, provides a framework to understand the etiology of complex neurodevelopmental disorders arising from rare missense variants in synaptic genes.

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Oocyte growth and follicular development in KIT-deficient Fas-knockout mice

Reproduction ◽

10.1530/rep-06-0161 ◽

2007 ◽

Vol 133 (1) ◽

pp. 117-125 ◽

Cited By ~ 26

Author(s):

Mohammad Moniruzzaman ◽

Kazuhiro Sakamaki ◽

Yukiko Akazawa ◽

Takashi Miyano

Keyword(s):

Germ Cells ◽

Death Receptor ◽

Follicular Development ◽

Tyrosine Kinase Receptor ◽

Wild Type ◽

Oocyte Growth ◽

Immunodeficient Mice ◽

Deficient Mice ◽

Receptor Family

In mammals, oocyte growth and follicular development are known to be regulated by KIT, a tyrosine kinase receptor. Fas is a member of the death receptor family inducing apoptosis. Here, we investigated germ cell survival, oocyte growth and follicular development in KIT-deficient (Wv/Wv:Fas+/+), Fas-deficient (+/+:Fas−/−), and both KIT- and Fas-deficient (Wv/Wv:Fas−/−) mice during fetal and postnatal periods. Further, the ovaries of these mice were transplanted in immunodeficient mice to compare oocyte growth and follicular development under a condition isolated from the extraovarian effects of KIT- and Fas-deficiency. Higher numbers of germ cells were found in the fetal and postnatal ovaries of Fas-deficient mice than in the same-aged wild-type mice. In KIT-deficient mice, ovaries at 13 dayspostcoitum(dpc) contained 1106±72 (n=3) germ cells, but the ovaries contained no oocytes after birth. Twenty-one days after transplantation of the ovaries at 13 dpc, no oocytes/germ cells were found. A higher number of germ cells (3843±108;n=3) were observed in the Wv/Wv:Fas−/−genotypes than in Wv/Wv:Fas+/+mice at 13 dpc. Furthermore, Wv/Wv:Fas−/−mice contained 528±91 (n=3) oocytes at 2 days, and follicles developed to the antral stage at 14 days of age. After transplantation of fetal and neonatal ovaries from Wv/Wv:Fas−/−mice, increased numbers of growing oocytes and developing follicles were obtained compared with those in 14-day old ovariesin vivo. These results show that oocytes grow and follicles develop without KIT signaling, although KIT might be essential for the survival of germ cells/oocytes in mice.

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Effect of N -methyl-d-aspartate Receptor ε1Subunit Gene Disruption of the Action of General Anesthetic Drugs in Mice

Anesthesiology ◽

10.1097/00000542-200503000-00013 ◽

2005 ◽

Vol 102 (3) ◽

pp. 557-561 ◽

Cited By ~ 53

Author(s):

Yuki Sato ◽

Eiji Kobayashi ◽

Takanori Murayama ◽

Masayoshi Mishina ◽

Norimasa Seo

Keyword(s):

Nitrous Oxide ◽

Nmda Receptor ◽

Knockout Mice ◽

Gamma Aminobutyric Acid ◽

Wild Type ◽

General Anesthetic ◽

Hypnotic Effect ◽

Anesthetic Agents ◽

Anesthetic Drugs

Background Recent molecular strategies demonstrated that the N-methyl-d-aspartate (NMDA) receptor is a major target site of anesthetic agents. In a previous article, the authors showed that knocking out the NMDA receptor epsilon1 subunit gene markedly reduced the hypnotic effect of ketamine in mice. In the current study, the authors examined the in vivo contribution of the NMDA receptor epsilon1 subunit to the action of other anesthetic drugs. Methods The authors determined the anesthetic effects of nitrous oxide on sevoflurane potency in NMDA receptor epsilon1 subunit knockout mice compared with those in wild-type mice. They then tested the hypnotic effect of gamma-aminobutyric acid-mediated agents, such as propofol, pentobarbital, diazepam, and midazolam, in knockout mice and wild-type mice. Results The anesthetic action of sevoflurane itself was unaffected by the abrogation of the NMDA receptor epsilon1 subunit. Adding nitrous oxide reduced the required concentration of sevoflurane to induce anesthesia in wild-type mice, whereas this sparing effect was diminished in knockout mice. Furthermore, propofol, pentobarbital, diazepam, and midazolam also had markedly attenuated effects in knockout mice. Conclusions Although it has been demonstrated that knocking out the expression of receptors may induce changes in the composition of the subunits, the network circuitry, or both, the current findings show consistently that the NMDA receptor epsilon1 subunit mediates nitrous oxide but not sevoflurane anesthesia. Furthermore, the attenuated anesthetic impact of propofol, pentobarbital, diazepam, and midazolam as well as ketamine in knockout mice suggests that the NMDA receptor epsilon1 subunit could be indirectly involved in the hypnotic action of these drugs in vivo.

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The connectome predicts resting state functional connectivity across the Drosophila brain

10.1101/2020.12.11.422105 ◽

2020 ◽

Cited By ~ 1

Author(s):

Maxwell H Turner ◽

Kevin Mann ◽

Thomas R. Clandinin

Keyword(s):

Functional Connectivity ◽

Large Scale ◽

Neural Circuit ◽

Brain Networks ◽

Brain Regions ◽

Central Complex ◽

Resting State Functional Connectivity ◽

Brain Structure And Function ◽

And Function

Connectomic datasets have emerged as invaluable tools for understanding neural circuits in many systems. What constraints does the connectome place on information processing and routing in a large scale neural circuit? For mesoscale brain networks, the relationship between cell and synaptic level connectivity and brain function is not well understood. Here, we use data from the Drosophila connectome in conjunction with whole-brain in vivo imaging to relate structural and functional connectivity in the central brain. We find that functional connectivity is strongly associated with the strength of both direct and indirect anatomical pathways. We also show that some brain regions, including the mushroom body and central complex, show considerably higher functional connectivity to other brain regions than is predicted based on their direct anatomical connections. We find several key topological similarities between mesoscale brain networks in flies and mammals, revealing conserved principles relating brain structure and function.

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Chromatin remodelers clear nucleosomes from intrinsically unfavorable sites to establish nucleosome-depleted regions at promoters

Molecular Biology of the Cell ◽

10.1091/mbc.e10-10-0826 ◽

2011 ◽

Vol 22 (12) ◽

pp. 2106-2118 ◽

Cited By ~ 21

Author(s):

Denis Tolkunov ◽

Karl A. Zawadzki ◽

Cara Singer ◽

Nils Elfving ◽

Alexandre V. Morozov ◽

...

Keyword(s):

Dna Sequences ◽

Large Scale ◽

Gene Promoters ◽

Wild Type ◽

Nucleosome Remodeling ◽

Chromatin Remodelers ◽

Transcriptional Reprogramming ◽

Nucleosome Structure ◽

Nucleosome Formation

Most promoters in yeast contain a nucleosome-depleted region (NDR), but the mechanisms by which NDRs are established and maintained in vivo are currently unclear. We have examined how genome-wide nucleosome placement is altered in the absence of two distinct types of nucleosome remodeling activity. In mutants of both SNF2, which encodes the ATPase component of the Swi/Snf remodeling complex, and ASF1, which encodes a histone chaperone, distinct sets of gene promoters carry excess nucleosomes in their NDRs relative to wild-type. In snf2 mutants, excess promoter nucleosomes correlate with reduced gene expression. In both mutants, the excess nucleosomes occupy DNA sequences that are energetically less favorable for nucleosome formation, indicating that intrinsic histone–DNA interactions are not sufficient for nucleosome positioning in vivo, and that Snf2 and Asf1 promote thermodynamic equilibration of nucleosomal arrays. Cells lacking SNF2 or ASF1 still accomplish the changes in promoter nucleosome structure associated with large-scale transcriptional reprogramming. However, chromatin reorganization in the mutants is reduced in extent compared to wild-type cells, even though transcriptional changes proceed normally. In summary, active remodeling is required for distributing nucleosomes to energetically favorable positions in vivo and for reorganizing chromatin in response to changes in transcriptional activity.

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Deep multitask learning of gene risk for comorbid neurodevelopmental disorders

10.1101/2020.06.13.150201 ◽

2020 ◽

Author(s):

Ilayda Beyreli ◽

Oguzhan Karakahya ◽

A. Ercument Cicek

Keyword(s):

Neurodevelopmental Disorders ◽

Large Scale ◽

Susceptibility Gene ◽

Autism Spectrum ◽

Multitask Learning ◽

Risk Genes ◽

Risk Prioritization ◽

Sequencing Studies ◽

Number Variation ◽

Spatio Temporal

AbstractAutism Spectrum Disorder (ASD) and Intellectual Disability (ID) are comorbid neurodevelopmental disorders with complex genetic architectures. Despite large-scale sequencing studies only a fraction of the risk genes were identified for both. Here, we present a novel network-based gene risk prioritization algorithm named DeepND that performs cross-disorder analysis to improve prediction power by exploiting the comorbidity of ASD and ID via multitask learning. Our model leverages information from gene co-expression networks that model human brain development using graph convolutional neural networks and learns which spatio-temporal neurovelopmental windows are important for disorder etiologies. We show that our approach substantially improves the state-of-the-art prediction power in both single-disorder and cross-disorder settings. DeepND identifies mediodorsal thalamus and cerebral cortex brain region and infancy to childhood period as the highest neurodevelopmental risk window for both ASD and ID. We observe that both disorders are enriched in transcription regulators. Despite tight regulatory links in between ASD risk genes, such is lacking across ASD and ID risk genes or within ID risk genes. Finally, we investigate frequent ASD and ID associated copy number variation regions and confident false findings to suggest several novel susceptibility gene candidates. DeepND can be generalized to analyze any combinations of comorbid disorders and is released at http://github.com/ciceklab/deepnd.

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