The homeobox containing gene Arx is expressed during ventral telencephalon development and it is required for correct GABAergic interneuron tangential migration from the ganglionic eminences to the olfactory bulbs, cerebral cortex and striatum. Its human ortholog is associated with a variety of neurological clinical manifestations whose syntoms are compatible with a loss of cortical interneurons and altered basal ganglia related-activities in humans. Herein, we reported the identification by global expression profiling of a group of genes whose expression is consistently altered in Arx mutant ganglionic eminences. Following analysis revealed the striking ectopic expression in the ganglionic eminences of a number of genes normally not, or only marginally, expressed in the ventral telencephalon. Among them, we functionally analyzed Ebf3, whose ectopic expression in ventral telencephalon is preventingneuronal tangential migration. Further, we showed that Arx is sufficient to repress Ebf3 endogenous expression and that its silencing in Arx mutant tissue might marginally rescue tangential cell movements. Together, these data provide an initial analysis of the molecular pathways regulated by Arx and how their networking might regulate those specific cellular processes during telencephalon development strongly altered by loss of Arx.
Arx acts as a regional key selector gene in the ventral telencephalon mainly through its transcriptional repression activity.
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View SamplesAQM shows acute muscle wasting and weakness. Key aspects of AQM include muscle atrophy and myofilament loss. Gene expression profiling, using muscle biopsies from AQM, neurogenic atrophy and normal controls, showed that both myogenic and neurogenic atrophy share induction of myofiber-specific ubiquitin/proteosome pathways while only the AQM shows a specific strong induction of transforming growth factor (TGF)-beta/MAPK pathways.
Constitutive activation of MAPK cascade in acute quadriplegic myopathy.
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The Tbr2 Molecular Network Controls Cortical Neuronal Differentiation Through Complementary Genetic and Epigenetic Pathways.
Specimen part
View SamplesThe abscence of TBR2 gene in human leads to microcephaly. This condition is mimicked by the specific ablation of the murine gene in developing cerebral cortex. Herein we compared gene expression in control and Tbr2 cKO in E14.5 cerebral cortices. This approach represents a useful tool to identify the molecular mechanisms at the basis of the phenotype.
The Tbr2 Molecular Network Controls Cortical Neuronal Differentiation Through Complementary Genetic and Epigenetic Pathways.
Specimen part
View SamplesSoft tissue sarcomas are a diverse set of fatal human tumors where few agents have demonstrable clinical efficacy, with the standard therapeutic combination of doxorubicin and ifosfamide showing only a 25-30% response rate in large multi-institutional trials. Although liposarcomas are the most common histological form of adult soft tissue sarcomas, research in this area is severely hampered by the lack of experimentally tractable in vitro model systems. To this end, here we describe a novel in vitro model for human pleomorphic liposarcoma. The cell line (LS2) is derived from a pleomorphic liposarcoma that utilizes Alternative Lengthening of Telomeres (ALT) mechanism of telomere maintenance, which may be particularly important in modulating the response of this tumor type to DNA damaging agents. We present detailed baseline molecular and genomic data, including genome wide copy number and transcriptome profiles, for this model compared to its parental tumor and a panel of liposarcomas covering multiple histologies. The model has retained essentially all of the detectable alterations in copy number that are seen in the parental tumor, and shows molecular karyotypic and expression profiles consistent with pleomorphic liposarcomas. We also demonstrate the utility of this model, together with two additional human liposarcoma cell lines, to investigate the relationship between topoisomerase 2A expression and the sensitivity of ALT-positive liposarcomas to doxorubicin. This model, together with its associated baseline data, provide a powerful new tool to develop treatments for this clinically poorly-tractable tumor, and to investigate the contribution that ALT makes to modulating sensitivity to DNA damaging chemotherapeutic agents such as doxorubicin.
Doxorubicin resistance in a novel in vitro model of human pleomorphic liposarcoma associated with alternative lengthening of telomeres.
Cell line
View SamplesA gene expression signature purporting to distinguish between telomerase and ALT immortalization has recently been described (Lafferty-Whyte et al., 2009). This was obtained as the intersection of two independent signatures, one obtained from cell lines and the other from a panel of liposarcomas, which utilize different telomere maintenance mechanisms (TMMs). To assess the utility of this signature we used Affymetrix U133plus2.0 arrays to undertake a similar analysis of an independent collection of liposarcomas of defined TMM. In our dataset, the 297 gene signature causes the liposarcomas to cluster not on the basis of TMM, but rather on the basis of tumor histological subtype [Figure 1], consistent with the signatures reported by others (Matushansky et al., 2008).
Validating a gene expression signature proposed to differentiate liposarcomas that use different telomere maintenance mechanisms.
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View SamplesDirect cell reprogramming has enabled the direct conversion of skin fibroblasts into functional neurons and oligodendrocytes using a minimal set of cell lineage-specific transcription factors. This approach has substantial advantages since it is rapid and simple, generating the cell type of interest in a single step. However, it remains unknown whether this technology can be applied for directly reprogramming skin cells into astrocytes, the third neural lineage. Astrocytes play crucial roles in neuronal homeostasis and their dysfunctions contribute to the origin and progression of multiple human diseases. Herein, we carried out a screening using several transcription factors involved in defining the astroglial cell fate and identified NFIA, NFIB and SOX9 to be sufficient to convert with high efficiency embryonic and post-natal mouse fibroblasts into astrocytes (iAstrocytes). We proved both by gene expression profiling and functional tests that iAstrocytes are comparable to native brain astrocytes. This protocol can be then employed to generate functional iAstrocytes for a wide range of experimental applications.
Direct conversion of fibroblasts into functional astrocytes by defined transcription factors.
Specimen part
View SamplesTransdifferentiation of fibroblasts into induced Neuronal cells (iNs) by neuronal-specific transcription factors Brn2, Myt1l and Ascl1 is a paradigmatic example of inter-lineage conversion across epigenetically distant cells. Despite tremendous progress on the transcriptional hierarchy underlying transdifferentiation, the enablers of the concomitant epigenome resetting remain to be elucidated. Here we investigated the role of KMT2A and KMT2B, two histone H3 lysine 4 methylases with cardinal roles in development, through individual and combined inactivation. We found that Kmt2b, whose human homologue's mutations cause dystonia, is selectively required for iN conversion through the suppression of the alternative myocyte program and the induction of neuronal maturation genes. Overall design: In order to study the role of KMT2A and KMT2B during transdifferentiation, we employed conditional mouse strains carrying: i) the exon 2 of Kmt2a and/or Kmt2b flanked by LoxP sites; ii) the knock-in of the YFP-coding gene into one Rosa26 allele, downstream of a LoxP-flanked transcription termination cassette (STOP cassette); and iii) the gene coding for the tamoxifen-inducible version of Cre recombinase knocked into the second Rosa26 allele (Glaser et al., 2006; Kranz et al., 2010; Testa et al., 2004). MEFs were derived from Kmt2a (and/or Kmt2b)fl/fl Cre+ YFP+ embryos and from Kmt2a+/+Kmt2b+/+ Cre+ YFP+ or Kmt2afl/+ Cre+ YFP+ for Kmt2a conditional KO (cKO) as controls (Figure 1A), and were subjected to transdifferentiation. After 13 days of BAM treatment, cells were FACS sorted for PSA-NCAM expression, and the transcriptome of positive and negative cells were independently profiled.
KMT2B Is Selectively Required for Neuronal Transdifferentiation, and Its Loss Exposes Dystonia Candidate Genes.
Specimen part, Subject
View SamplesAlbeit increased serum CK level and abnormal muscle histology are always present, boys with DMD are phenotipically indistinguishable from the normal ones at birth and, in their first years of life, acquire early motor milestones at normal times. A clear defect in muscle function becomes generally apparent by the end of the second year. As the disease is typically diagnosed between the ages of 3 and 7, the first two years are often considered and referred to as clinically presymptomatic.
Gene expression profiling in the early phases of DMD: a constant molecular signature characterizes DMD muscle from early postnatal life throughout disease progression.
Sex, Age
View SamplesLineage-specific transcription factors, which drive cellular identity during embryogenesis, have been shown to convert cell fate when express ectopically in heterologous cells. Herein, we screened the key molecular factors governing the dopaminergic neuronal specification during brain development for their ability to generate similar neurons directly from mouse and human fibroblasts. Remarkably, we found a minimal set of three factors Mash1, Nurr1 and Lmx1a/b able to elicit such cellular reprogramming. Molecular and transcriptome studies showed reprogrammed DA neurons to faithfully recapitulate gene expression of their brain homolog cells while lacking expression of other catecholaminergic neuronal types. Induced neurons showed spontaneous electrical activity organized in regular spikes consistent with the pacemaker activity featured by brain DA neurons. The three factors were able to elicit DA neuronal conversion in human fibroblasts from prenatal or adult fibroblasts of healthy donors and a Parkinsons disease patient. Generation of DA induced neurons from somatic cells might have significant implications in studies of neural development, disease in vitro modeling and cell replacement therapies.
Direct generation of functional dopaminergic neurons from mouse and human fibroblasts.
Specimen part
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