scholarly journals Chd8 haploinsufficiency impairs early brain development and protein homeostasis later in life

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jessica A. Jiménez ◽  
Travis S. Ptacek ◽  
Alex H. Tuttle ◽  
Ralf S. Schmid ◽  
Sheryl S. Moy ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cerebral Cortex ◽  
Er Stress ◽  
Stop Codon ◽  
Autism Spectrum ◽  
Mutant Mice ◽  
Wild Type ◽  
Age Related ◽  
Transcriptional Changes ◽  
Regulated Gene Expression

Abstract Background Chromodomain helicase DNA-binding protein 8 (Chd8) is a high-confidence risk gene for autism spectrum disorder (ASD). However, how Chd8 haploinsufficiency impairs gene expression in the brain and impacts behavior at different stages of life is unknown. Methods We generated a mutant mouse line with an ASD-linked loss-of-function mutation in Chd8 (V986*; stop codon mutation). We examined the behavior of Chd8 mutant mice along with transcriptional changes in the cerebral cortex as a function of age, with a focus on one embryonic (E14.5) and three postnatal ages (1, 6, and 12 months). Results Chd8V986*/+ mutant mice displayed macrocephaly, reduced rearing responses and reduced center time in the open field, and enhanced social novelty preference. Behavioral phenotypes were more evident in Chd8V986*/+ mutant mice at 1 year of age. Pup survival was reduced in wild-type x Chd8V986*/+ crosses when the mutant parent was female. Transcriptomic analyses indicated that pathways associated with synaptic and neuronal projections and sodium channel activity were reduced in the cortex of embryonic Chd8V986*/+ mice and then equalized relative to wild-type mice in the postnatal period. At 12 months of age, expression of genes associated with endoplasmic reticulum (ER) stress, chaperone-mediated protein folding, and the unfolded protein response (UPR) were reduced in Chd8V986*/+ mice, whereas genes associated with the c-MET signaling pathway were increased in expression. Limitations It is unclear whether the transcriptional changes observed with age in Chd8V986*/+ mice reflect a direct effect of CHD8-regulated gene expression, or if CHD8 indirectly affects the expression of UPR/ER stress genes in adult mice as a consequence of neurodevelopmental abnormalities. Conclusions Collectively, these data suggest that UPR/ER stress pathways are reduced in the cerebral cortex of aged Chd8V986*/+ mice. Our study uncovers neurodevelopmental and age-related phenotypes in Chd8V986*/+ mice and highlights the importance of controlling for age when studying Chd8 haploinsufficient mice.

scholarly journals An Autism-Associated Neuroligin-3 Mutation Affects Developmental Synapse Elimination in the Cerebellum

2021 ◽  
Vol 15 ◽  
Author(s):  
Esther Suk King Lai ◽  
Hisako Nakayama ◽  
Taisuke Miyazaki ◽  
Takanobu Nakazawa ◽  
Katsuhiko Tabuchi ◽  
...  
Keyword(s):  
Cell Adhesion Molecule ◽  
Synapse Formation ◽  
Single Point ◽  
Autism Spectrum ◽  
Mutant Mice ◽  
Single Point Mutation ◽  
Synapse Elimination ◽  
Wild Type ◽  
Post Mortem Brain ◽  
And Function

Neuroligin is a postsynaptic cell-adhesion molecule that is involved in synapse formation and maturation by interacting with presynaptic neurexin. Mutations in neuroligin genes, including the arginine to cystein substitution at the 451st amino acid residue (R451C) of neuroligin-3 (NLGN3), have been identified in patients with autism spectrum disorder (ASD). Functional magnetic resonance imaging and examination of post-mortem brain in ASD patients implicate alteration of cerebellar morphology and Purkinje cell (PC) loss. In the present study, we examined possible association between the R451C mutation in NLGN3 and synaptic development and function in the mouse cerebellum. In NLGN3-R451C mutant mice, the expression of NLGN3 protein in the cerebellum was reduced to about 10% of the level of wild-type mice. Elimination of redundant climbing fiber (CF) to PC synapses was impaired from postnatal day 10–15 (P10–15) in NLGN3-R451C mutant mice, but majority of PCs became mono-innervated as in wild-type mice after P16. In NLGN3-R451C mutant mice, selective strengthening of a single CF relative to the other CFs in each PC was impaired from P16, which persisted into juvenile stage. Furthermore, the inhibition to excitation (I/E) balance of synaptic inputs to PCs was elevated, and calcium transients in the soma induced by strong and weak CF inputs were reduced in NLGN3-R451C mutant mice. These results suggest that a single point mutation in NLGN3 significantly influences the synapse development and refinement in cerebellar circuitry, which might be related to the pathogenesis of ASD.

scholarly journals IreA controls endoplasmic reticulum stress-induced autophagy and survival through homeostasis recovery

2018 ◽  
pp. MCB.00054-18 ◽  
Author(s):  
Eunice Domínguez-Martín ◽  
Laura Ongay-Larios ◽  
Laura Kawasaki ◽  
Olivier Vincent ◽  
Gerardo Coello ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Cell Survival ◽  
Eukaryotic Cell ◽  
Functional Link ◽  
Unfolded Protein ◽  
Transcriptional Changes ◽  
The Unfolded Protein Response ◽  
Protein Response

The Unfolded Protein Response (UPR) is an adaptive pathway that restores cellular homeostasis after endoplasmic reticulum (ER) stress. The ER-resident kinase/ribonuclease Ire1 is the only UPR sensor conserved during evolution. Autophagy, a lysosomal degradative pathway, also contributes to the recovery of cell homeostasis after ER-stress but the interplay between these two pathways is still poorly understood. We describe the Dictyostelium discoideum ER-stress response and characterize its single bonafide Ire1 orthologue, IreA. We found that tunicamycin (TN) triggers a gene-expression reprogramming that increases the protein folding capacity of the ER and alleviates ER protein load. Further, IreA is required for cell-survival after TN-induced ER-stress and is responsible for nearly 40% of the transcriptional changes induced by TN. The response of Dictyostelium cells to ER-stress involves the combined activation of an IreA-dependent gene expression program and the autophagy pathway. These two pathways are independently activated in response to ER-stress but, interestingly, autophagy requires IreA at a later stage for proper autophagosome formation. We propose that unresolved ER-stress in cells lacking IreA causes structural alterations of the ER, leading to a late-stage blockade of autophagy clearance. This unexpected functional link may critically affect eukaryotic cell survival under ER-stress.

scholarly journals Two classes of mutant mammary tumor virus-infected HTC cell with defects in glucocorticoid-regulated gene expression.

1983 ◽  
Vol 3 (2) ◽  
pp. 149-160 ◽  
Author(s):  
G L Firestone ◽  
K R Yamamoto
Keyword(s):  
Gene Expression ◽  
Cell Surface ◽  
Mammary Tumor ◽  
Hormonal Regulation ◽  
Wild Type ◽  
Viral Glycoprotein ◽  
Mammary Tumor Virus ◽  
Viral Glycoproteins ◽  
Tumor Virus ◽  
Regulated Gene Expression

We have isolated mutant derivatives of M1.54 (a mammary tumor virus [MTV]-infected rat hepatoma [HTC] cell line containing multiple integrated proviruses) that fail to express hormone-inducible cell surface viral glycoproteins. In wild-type M1.54, the synthetic glucocorticoid dexamethasone selectively stimulates the rate of synthesis of MTV RNA. In addition, dexamethasone is essential for posttranslational maturation of three of the four cell surface viral glycoproteins processed from the MTV glycosylated precursor polyprotein; the fourth mature species is produced constitutively. Two mutant phenotypes are described; each contains glucocorticoid receptors that are indistinguishable from the wild-type receptor with respect to hormone affinity, intracellular concentration, nuclear translocation efficiency, DNA-cellulose chromatography, and sedimentation rate. In one class, represented by the mutant line CR1, dexamethasone fails to stimulate the low basal rate of MTV gene transcription; surprisingly, hormonal regulation of tyrosine aminotransferase activity is also defective in CR1, whereas several other cellular responses to dexamethasone are normal. In the second class of mutants, represented by CR4, dexamethasone stimulates synthesis of MTV transcripts indistinguishable from those produced in M1.54, but only the constitutive cell surface viral glycoprotein is expressed. Thus, these mutants define two distinct and novel aspects of glucocorticoid regulated gene expression in HTC cells: CR4 contains a defect in a hormone inducible protein maturation pathway that acts on specific viral (and presumably cellular) precursor polypeptides, whereas the lesion in CR1 appears to affect the expression of a subset of the gene products normally under glucocorticoid control in M1.54.

Comparison of Clinical and Biologic Significance of WT1 Mutations in Populations of Older (≥60 years[y]) and Younger (<60 y) Adult Patients (Pts) with Cytogenetically Normal (CN) De Novo Acute Myeloid Leukemia (AML): a Cancer and Leukemia Group B (CALGB) Study.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 326-326
Author(s):  
Heiko Becker ◽  
Guido Marcucci ◽  
Kati Maharry ◽  
Michael D. Radmacher ◽  
Krzysztof Mrózek ◽  
...  
Keyword(s):  
Gene Expression ◽  
De Novo ◽  
Age Groups ◽  
Stem Cell Marker ◽  
Treatment Intensity ◽  
Prognostic Impact ◽  
Wild Type ◽  
Age Related ◽  
Exon 9 ◽  
Wt1 Mutation

Abstract Abstract 326 Mutations of the Wilms tumor (WT1) gene are found in ∼10% of younger (<60 years[y]) adult pts with de novo CN-AML and impact adversely on their outcome. The clinical significance of WT1 mutations has not yet been evaluated in older (≥60 y) CN-AML pts. Therefore, we analyzed frequency and clinical impact of WT1 mutations in the context of other molecular markers in a relatively large cohort of 243 pts ≥60 y (range, 60-83 y) with de novo CN-AML treated intensively on upfront cytarabine/daunorubicin-based CALGB protocols. Included pts were those with material available for analysis of WT1 mutation status and that of a panel of other validated molecular prognosticators including NPM1, FLT3 (ie, FLT3-ITD, FLT3-TKD) and CEBPA mutations, BAALC and ERG expression levels. Mutations in WT1 “hot spots” (exons 7 and 9) were assessed by DHPLC and sequencing. The results were compared with the findings in younger (18-59 y) CALGB pts (n=207) characterized molecularly in a similar fashion. Gene expression profiles in both populations were assessed centrally using Affymetrix U133 plus 2.0 microchip. Among the 243 older pts, 16 (7%) had WT1 mutations. Of those, 14 had single WT1 mutations in exon 7 [frameshift (n=8), nonsense (n=1), and missense (n=1)] or in exon 9 [missense (n=4)]; 1 pt had 2 frameshift mutations in exon 7, and 1 had 1 frameshift mutation in exon 7 and 1 missense mutation in exon 9. Compared with older WT1 wild-type pts, older WT1 mutated pts more often had FLT3-ITD (P<.001) and had lower hemoglobin (P=.01), and higher WBC (P=.03) and % blood blasts (P=.03). WT1 mutated pts had a trend for lower complete remission (CR) rates (50% v 70%, P=.16) and shorter OS (P=.08; Figure 1), but similar disease-free survival (DFS; P=.59; Figure 2) compared with WT1 wild-type pts. The frequency of WT1 mutations tended to be lower in older than younger pts (7% v 12%, P=.07). Mutation types and pretreatment clinical and molecular characteristics associated with WT1 mutations were similar between the two age groups. Despite differences in treatment intensity, there were no significant differences in younger v older WT1 mutated pts with regard to CR rates (P=.18), or OS (P=.68; Figure 1) or DFS (P=.66; Figure 2) durations. In contrast, younger WT1 wild-type pts had significantly higher CR rates (P<.001), and longer OS (P<.001; Figure 1) and DFS (P<.001; Figure 2) than older WT1 wild-type pts. Although associated with WT1 mutations in both the younger (P=.02) and older age groups, FLT3-ITD had no impact on CR rates (P=.28), or OS (P=.15) or DFS (P=.21) durations of all WT1 mutated pts after controlling for age-related treatment intensity. To provide insights into the molecular features associated with WT1 mutations we analyzed the whole cohort (younger and older) for genes differentially expressed (ie, P≤.001) between WT1 mutated and WT1 wild-type pts. A signature comprising 110 named genes was derived. Among the 71 upregulated genes in WT1 mutated pts, were those encoding the leukemia stem cell marker CD96 and the leukemia fusion protein partners PML and MLL. The most upregulated gene (6.2 fold) was GTSF1, which, like WT1, may be involved in germ cell development. Among the 39 genes downregulated in WT1 mutated pts, were those encoding SNRPN and SNURF, involved in pre-mRNA processing, and the insulin receptor and IRS2, upstream effectors of the PI3K/AKT pathway. In conclusion, WT1 mutations in older CN-AML pts are less frequent than in younger pts. While WT1 mutations independently associate with shorter OS and DFS in younger CN-AML pts, in older CN-AML pts they are only associated with trends for a worse CR rate and shorter OS. This difference appears due to the poor outcome of the older compared to younger WT1 wild-type pts, which reduced the prognostic impact of WT1 mutations in the former. Nevertheless, the outcome of pts with WT1 mutations is equally poor in older and younger pts regardless of differences in treatment, thereby suggesting that WT1 mutated CN-AML may constitute a distinct biologic entity across age groups. The unique gene expression signature associated with WT1 mutations could provide useful insights into WT1 mutation-driven leukemogenic mechanisms across age-related groups, and help in devising novel molecular targeted therapeutic approaches for this subtype of CN-AML. Disclosures: No relevant conflicts of interest to declare.

The Interaction of MOZ-TIF2 with Histone Chaperon Proteins CAF-1A and Asf1b Alters MOZ Regulated Gene Expression.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2208-2208
Author(s):  
Hong Yin ◽  
Jonathan Glass ◽  
Kerry L. Blanchard
Keyword(s):  
Gene Expression ◽  
Gene Expression Profile ◽  
Expression Profile ◽  
Global Gene Expression ◽  
Chromatin Assembly ◽  
Wild Type ◽  
Terminal Portion ◽  
Hek 293 ◽  
Assembly Factors ◽  
Regulated Gene Expression

Abstract We have identified a MOZ-TIF2 (MT2) fusion gene containing the N-terminal portion of MOZ and the C-terminal portion of TIF2 from a patient with acute leukemia with a chromosome 8 translocation. We report here that MOZ portion of MOZ-TIF2 associates with chromatin assembly factors, CAF1 (chromatin assembly factor 1) and ASF1 (anti-silencing factor 1) in mammalian cells. Both proteins not only bring histones to newly synthesized DNA to create chromatin structure in the replication of chromosomes and DNA damage-repair processes but also contribute to regulation of global gene expression. Using the MOZ portion of MT2 as the bait in the yeast two hybrid system, we found that the MOZ portion interacted with CAF1A and Asf1b. The interactions were further verified with GST-pull down experiments. Interestingly, co-immunoprecipitation with whole cell extracts from HEK 293 cells transiently transfected with GFP fusions of MOZ, MT2, and TIF2 showed that only MOZ strongly co-precipitated with CAF1A while MT2 only weakly co-precipitated. In contrast to CAF1A, MT2 showed a 3-fold stronger binding to Asf1b than wild type MOZ in pull-down experiments using S-tagged Asf1b and EGFP-fusions of MOZ, MT2, and TIF2. Further analysis of the domains within the MOZ portion of MT2 responsible for the interaction of CAF1A and Asf1b with MT2 indicated that the binding of CAF1A predominately depended on the PHD domain of MOZ and amino acids176–327 of CAF1A. The MYST domain of MOZ was responsible for the binding of the MOZ portion of MT2 to Asf1b. To further verify the differential binding of MOZ and MT2 to CAF1A and Asf1b, we observed the co-localization of transiently expressed EGFP-MOZ and EGFP-MT2 with DsRed-CAF1A in HEK 293 and Hela cells. In the merged images the MOZ co-localization with CAF-1A was stronger than the colocalization of MT2 with CAF1A and MT2 colocalization with Asf1b was stronger than MOZ colocalization with Asf1b. The co-localization of MOZ and MT2 with CAF1A with Asf1b was seen both in interphase and metaphase of the cell cycle. During the interphase, the co-localizations appeared with chromatin DNA and during metaphase the co-localizations were separated from chromatin DNA. The later phenomenon was further demonstrated with G2/M phase reagent, nocodozole. These results suggest a differential function of MT2 interacting with two chromatin assembly factors compared to wild-type MOZ. In view of the regulation of global gene expression by CAF1A and Asf1b, we examined the gene expression profile in U937 cells stably expressing MT2. Compared to the expression profile of control cells stably transfected with pcDNA3 vector alone, MT2 caused a > 5-fold change in expression 181 genes (104 genes increasing and 77 genes decreasing expression) (p = 0.05). While overexpression of wild type MOZ also altered gene expression (>5-fold increase in 479 genes and >5-fold decrease in 118 genes) a differential gene expression signature was seen between MOZ and MT2. MT2 altered expression of 57% of the 597 MOZ regulated genes. Included in the genes that were either up or down-regulated by MT2 were genes involved in multiple cell functions such as signal transduction, cell response to stimulus, and development. These results suggest that MT2 fusion may interfere with the function of wild type MOZ in global gene expression during the development of myeloid cells by differential interaction with chromatin chaperon proteins and the altered global gene expression profile could contribute to leukemogenesis.

Clockmutation facilitates accumulation of cholesterol in the liver of mice fed a cholesterol and/or cholic acid diet

2008 ◽  
Vol 294 (1) ◽  
pp. E120-E130 ◽  
Author(s):  
Takashi Kudo ◽  
Mihoko Kawashima ◽  
Toru Tamagawa ◽  
Shigenobu Shibata
Keyword(s):  
Gene Expression ◽  
Circadian Clock ◽  
Cholic Acid ◽  
Mouse Liver ◽  
Clock Genes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Mutant Mice ◽  
Wild Type ◽  
Clock Mutant

Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor ( Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) ( Per2) and brain and muscle arnt-like protein-1 ( Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.

Iron absorption and hepatic iron uptake are increased in a transferrin receptor 2 (Y245X) mutant mouse model of hemochromatosis type 3

2007 ◽  
Vol 292 (1) ◽  
pp. G323-G328 ◽  
Author(s):  
S. F. Drake ◽  
E. H. Morgan ◽  
C. E. Herbison ◽  
R. Delima ◽  
R. M. Graham ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mouse Model ◽  
Transferrin Receptor ◽  
Mutant Mouse ◽  
Hereditary Hemochromatosis ◽  
Mutant Mice ◽  
Wild Type ◽  
Hepcidin Expression ◽  
Fe Uptake ◽  
Type 3

Hereditary hemochromatosis type 3 is an iron (Fe)-overload disorder caused by mutations in transferrin receptor 2 (TfR2). TfR2 is expressed highly in the liver and regulates Fe metabolism. The aim of this study was to investigate duodenal Fe absorption and hepatic Fe uptake in a TfR2 (Y245X) mutant mouse model of hereditary hemochromatosis type 3. Duodenal Fe absorption and hepatic Fe uptake were measured in vivo by 59Fe-labeled ascorbate in TfR2 mutant mice, wild-type mice, and Fe-loaded wild-type mice (2% dietary carbonyl Fe). Gene expression was measured by real-time RT-PCR. Liver nonheme Fe concentration increased progressively with age in TfR2 mutant mice compared with wild-type mice. Fe absorption (both duodenal Fe uptake and transfer) was increased in TfR2 mutant mice compared with wild-type mice. Likewise, expression of genes participating in duodenal Fe uptake ( Dcytb, DMT1) and transfer (ferroportin) were increased in TfR2 mutant mice. Nearly all of the absorbed Fe was taken up rapidly by the liver. Despite hepatic Fe loading, hepcidin expression was decreased in TfR2 mutant mice compared with wild-type mice. Even when compared with Fe-loaded wild-type mice, TfR2 mutant mice had increased Fe absorption, increased duodenal Fe transport gene expression, increased liver Fe uptake, and decreased liver hepcidin expression. In conclusion, despite systemic Fe loading, Fe absorption and liver Fe uptake were increased in TfR2 mutant mice in association with decreased expression of hepcidin. These findings support a model in which TfR2 is a sensor of Fe status and regulates duodenal Fe absorption and liver Fe uptake.

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