Project description:Background: Severe combined immunodeficiency (SCID) is characterized by arrested T lymphocyte production and B lymphocyte dysfunction, resulting in life-threatening infections. Early diagnosis of SCID through population-based newborn screening (NBS) optimizes clinical management and outcomes, and also permits identification of previously unknown factors essential for human lymphocyte development. Methods: SCID was detected, prior to onset of infections, by NBS of T cell receptor excision circles, a biomarker for thymic output. Upon confirmation, the affected baby was treated by allogeneic hematopoietic cell transplantation (HCT). The genetic cause was sought by exome sequencing of the patient and parents, followed by functional analysis of a prioritized candidate gene using human hematopoietic stem cells (HSC) and zebrafish embryos. Results: An infant with leaky SCID, craniofacial and dermal abnormalities, and absent corpus callosum had his immune deficit fully corrected by HCT. Exome sequencing revealed a heterozygous, de novo, missense mutation pN441K in BCL11B. The mutant Bcl11b protein had dominant negative activity, abrogating the ability of wild type Bcl11b to bind DNA, arresting T cell lineage development and disrupting HSC migration, revealing a novel function of Bcl11b. The patientâs defects, recapitulated in Bcl11b-deficient zebrafish, were reversed by ectopic expression of intact, but not mutant, human BCL11B. Conclusions: Newborn screening facilitated treatment and identification of a novel etiology for human SCID. Coupling exome sequencing with candidate gene evaluation in human HSC and in zebrafish revealed that a constitutional BCL11B mutation causes human multisystem anomalies with SCID, while also revealing a novel, pre-thymic role for Bcl11b in hematopoietic progenitors. 3 samples were analyzed in duplicate, Sample 1 was human HSC transduced with GFP only lentivirus which served as controls, Sample 2 was human HSC transduced with lentivirus expressing FLAG-tagged WT BCL11B and GFP, Sample 3 was human HSC transduced with lentivirus expressing FLAG-tagged mutant BCL11B and GFP
Project description:To understand the molecular basis of neurodevelopmental abnormalities in HSAN1E disorder associated with DNMT1 Y495C mutation, we have developed transgenic mouse ES lines (R1Dnmt1 Y495C) that expresses mutant transcripts in addition to the endogenous wild-type transcripts. We also generated a transgenic cell line that overexpresses the wild-type transcripts (R1wt Dnmt1) to segregate the effects of mutant proteins. We performed transcriptome profiling of mESC lines and their neuronal derivatives using RNA-seq. Dysregulated transcripts in R1wt Dnmt1 and R1Dnmt1 Y495C mESCs and neurons were identified by comparisons with the wild-type counterpart (R1; wild-type mESC line). Gene ontology and pathway enrichment analysis were performed to identify potential pathways and key regulatory genes underlying the HSAN1E associated neurodevelopmental phenotypes.
Project description:Background: Severe combined immunodeficiency (SCID) is characterized by arrested T lymphocyte production and B lymphocyte dysfunction, resulting in life-threatening infections. Early diagnosis of SCID through population-based newborn screening (NBS) optimizes clinical management and outcomes, and also permits identification of previously unknown factors essential for human lymphocyte development. Methods: SCID was detected, prior to onset of infections, by NBS of T cell receptor excision circles, a biomarker for thymic output. Upon confirmation, the affected baby was treated by allogeneic hematopoietic cell transplantation (HCT). The genetic cause was sought by exome sequencing of the patient and parents, followed by functional analysis of a prioritized candidate gene using human hematopoietic stem cells (HSC) and zebrafish embryos. Results: An infant with leaky SCID, craniofacial and dermal abnormalities, and absent corpus callosum had his immune deficit fully corrected by HCT. Exome sequencing revealed a heterozygous, de novo, missense mutation pN441K in BCL11B. The mutant Bcl11b protein had dominant negative activity, abrogating the ability of wild type Bcl11b to bind DNA, arresting T cell lineage development and disrupting HSC migration, revealing a novel function of Bcl11b. The patient’s defects, recapitulated in Bcl11b-deficient zebrafish, were reversed by ectopic expression of intact, but not mutant, human BCL11B. Conclusions: Newborn screening facilitated treatment and identification of a novel etiology for human SCID. Coupling exome sequencing with candidate gene evaluation in human HSC and in zebrafish revealed that a constitutional BCL11B mutation causes human multisystem anomalies with SCID, while also revealing a novel, pre-thymic role for Bcl11b in hematopoietic progenitors.
Project description:Twelve human THAP proteins share the THAP domain, an evolutionary conserved zinc-finger DNA-binding domain. Studies of different THAP proteins have indicated roles in gene transcription, cell proliferation and development. We have analyzed this protein family, focusing on THAP7 and THAP11. We show that human THAP proteins possess differing homo- and heterodimer formation properties and interaction abilities with the transcriptional co-regulator HCF-1. HEK-293 cells lacking THAP7 were viable but proliferated more slowly. In contrast, HEK-293 cells were very sensitive to THAP11 alteration. Nevertheless, HEK-293 cells bearing a human THAP11 mutation identified in a patient suffering from cobalamin disorder (THAP11F80L) were viable although proliferated more slowly. Cobalamin disorder is an inborn vitamin deficiency characterized by neurodevelopmental abnormalities, most often due to biallelic mutations in the MMACHC gene, whose gene product MMACHC is a key enzyme in the cobalamin metabolic pathway. We show that THAP11F80L selectively affected promoter binding by THAP11, having more deleterious effects on a subset of THAP11 targets, and resulting in altered patterns of gene expression. In particular, THAP11F80L exhibited a strong effect on association with the MMACHC promoter and led to a decrease in MMACHC gene transcription, suggesting that the THAP11F80L mutation is directly responsible for the observed cobalamin disorder.
Project description:Chromodomain helicase DNA-binding 8 (CHD8) is one of the most frequently mutated genes causative of autism spectrum disorder (ASD). While its phenotypic spectrum often encompasses macrocephaly and hence implicates cortical abnormalities in this form of ASD, the neurodevelopmental impact of human CHD8 haploinsufficiency remains unexplored. Here we combined human cerebral organoids and single cell transcriptomics to define the effect of ASD-linked CHD8 mutations on human cortical development. We found that CHD8 haploinsufficiency causes a major disruption of neurodevelopmental trajectories with an accelerated generation of inhibitory neurons and a delayed production of excitatory neurons alongside the ensuing protraction of the proliferation phase. This imbalance may contribute to the significant enlargement of cerebral organoids in line with the macrocephaly observed in patients with CHD8 mutations. By adopting an isogenic design of patient-specific mutations and mosaic cerebral organoids, we define genotype-phenotype relationships and uncover their cell-autonomous nature. Finally, our results assign different CHD8-dependent molecular defects to particular cell types, pointing to an abnormal and extended program of proliferation and alternative splicing specifically affected in, respectively, the radial glial and immature neuronal compartments. By identifying temporally restricted cell-type specific effects of human CHD8 mutations, our study uncovers developmental alterations as reproducible endophenotypes for neurodevelopmental disease modelling.
Project description:Bcl11b plays an important role in postnatal dentate gyrus development and adult neurogenesis. To determine its role in adult neurogenesis independant from postnatal development the Bcl11b mutation was induced at the age of 2 months. Microarray analysis was performed on RNA isolated 4 weeks after the induction of the Bcl11b mutation to determine Bcl11b target genes.
Project description:Fragile X Syndrome (FXS) is a neurodevelopmental disorder caused by epigenetic silencing of FMR1 and loss of FMRP expression. Here we describe the establishment of an isogenic human pluripotent embryonic stem cell model of FXS. Using CRISPR/Cas9 to introduce indels in exon 3 of FMR1 and result in complete loss of FMRP (FMR1KO). We show that FMRP-deficient neurons exhibit a number of phenotypic abnormalities including neurite outgrowth and branching deficits and impaired electrophysiological network activity as measured by multi-electrode arrays. RNA-Seq analysis of FMRP-deficient neurons revealed transcriptional dysregulation in pathways related to neurodevelopment, neurotransmission, and the cell cycle
Project description:Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by maternal mutation and paternal imprinting of the gene encoding UBE3A, an E3 ubiquitin ligase. Although several potential target proteins of UBE3A have been reported, how these proteins regulate neuronal development remains unclear. We performed a large-scale quantitative proteomic analysis using stable-isotope labeling of amino acids in mammals (SILAM) on mice with maternal Ube3a mutation.
Project description:Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in the transcriptional regulator MeCP2. RTT is characterized by having apparently normal development until 6-18 months, when a progressive decline in motor and language functions begins and breathing abnormalities and seizures present. Here we present the first proteomic analysis in a RTT mouse model. Examining whole cortex tissue in symptomatic males (Mecp2Jae/y) and wild-type littermates, we have identified 465 proteins significantly altered. Pathway analysis identified biological pathways ubiquitous to multiple cell types as well as cell type specific pathways, underscoring the contributions of multiple central nervous system (CNS) cell populations to the disease pathogenesis.