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Expression data from wild type and Ctip2-/- (Bcl11b) mutant mouse striatum at P0

ABSTRACT: Striatal medium spiny neurons (MSN) are critically involved in motor control, and their degeneration is a principal component of Huntington’s disease. We find that the transcription factor Ctip2 (also known as Bcl11b) is central to MSN differentiation and striatal development. Within the striatum, it is expressed by all MSN, while it is excluded from essentially all striatal interneurons. In the absence of Ctip2, MSN do not fully differentiate, as demonstrated by dramatically reduced expression of a large number of MSN markers, including DARPP-32, FOXP1, Chrm4, Reelin, MOR1, GluR1, and Plexin-D1. Furthermore, MSN fail to aggregate into patches, resulting in severely disrupted patch-matrix organization within the striatum. Finally, heterotopic cellular aggregates invade the Ctip2-/- striatum suggesting a failure by MSN to repel these cells in the absence of Ctip2. In order to investigate the molecular mechanisms that underlie Ctip2-dependent differentiation of MSN and that underlie the patch-matrix disorganization in the mutant striatum, we directly compared gene expression between wild type and mutant striatum at P0. Because CTIP2-expressing MSN constitute 90-95% of the neurons within the striatum, we reasoned that we should be able to detect changes in medium spiny neuron gene expression in Ctip2 null mutants. We microdissected out small regions of striatum at matched locations in wild type and Ctip2-/- mutant littermates at P0 and investigated gene expression with Affymetrix microarrays. We selected the 153 most significant genes and further analyzed them to identify a smaller set of genes of potentially high biological relevance. In order to verify the microarray data and define the distribution of the identified genes in the striatum, we performed in situ hybridization or immunohistochemistry for 12 selected genes: Plexin-D1, Ngef, Nectin-3, Kcnip2, Pcp4L1, Neto1, Basonuclin 2, Fidgetin, Semaphorin 3e, Secretagogin, Unc5d, and Neurotensin. We find that all these genes are either specifically downregulated (Plexin-D1, Ngef, Nectin-3 Kcnip2, Pcp4L1, Neto1), or upregulated (Basonuclin 2, Fidgetin, Semaphorin 3e, Secretagogin, Unc5d, Neurotensin), in the Ctip2-/- striatum, confirming and extending the microarray results. Together, these data indicate that Ctip2 is a critical regulator of MSN differentiation, striatal patch development, and the establishment of the cellular architecture of the striatum. Keywords: mutant analysis

ORGANISM(S): Mus musculus

PROVIDER: GSE9330 | GEO | 2007/12/15

SECONDARY ACCESSION(S): PRJNA103005

REPOSITORIES: GEO

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Project description:Striatal medium spiny neurons (MSN) are critically involved in motor control, and their degeneration is a principal component of Huntingtonâs disease. We find that the transcription factor Ctip2 (also known as Bcl11b) is central to MSN differentiation and striatal development. Within the striatum, it is expressed by all MSN, while it is excluded from essentially all striatal interneurons. In the absence of Ctip2, MSN do not fully differentiate, as demonstrated by dramatically reduced expression of a large number of MSN markers, including DARPP-32, FOXP1, Chrm4, Reelin, MOR1, GluR1, and Plexin-D1. Furthermore, MSN fail to aggregate into patches, resulting in severely disrupted patch-matrix organization within the striatum. Finally, heterotopic cellular aggregates invade the Ctip2-/- striatum suggesting a failure by MSN to repel these cells in the absence of Ctip2. In order to investigate the molecular mechanisms that underlie Ctip2-dependent differentiation of MSN and that underlie the patch-matrix disorganization in the mutant striatum, we directly compared gene expression between wild type and mutant striatum at P0. Because CTIP2-expressing MSN constitute 90-95% of the neurons within the striatum, we reasoned that we should be able to detect changes in medium spiny neuron gene expression in Ctip2 null mutants. We microdissected out small regions of striatum at matched locations in wild type and Ctip2-/- mutant littermates at P0 and investigated gene expression with Affymetrix microarrays. We selected the 153 most significant genes and further analyzed them to identify a smaller set of genes of potentially high biological relevance. In order to verify the microarray data and define the distribution of the identified genes in the striatum, we performed in situ hybridization or immunohistochemistry for 12 selected genes: Plexin-D1, Ngef, Nectin-3, Kcnip2, Pcp4L1, Neto1, Basonuclin 2, Fidgetin, Semaphorin 3e, Secretagogin, Unc5d, and Neurotensin. We find that all these genes are either specifically downregulated (Plexin-D1, Ngef, Nectin-3 Kcnip2, Pcp4L1, Neto1), or upregulated (Basonuclin 2, Fidgetin, Semaphorin 3e, Secretagogin, Unc5d, Neurotensin), in the Ctip2-/- striatum, confirming and extending the microarray results. Together, these data indicate that Ctip2 is a critical regulator of MSN differentiation, striatal patch development, and the establishment of the cellular architecture of the striatum. Experiment Overall Design: Matched regions of striatum from wild type and Ctip2-/- mice were obtained via 500 Âµm diameter punch biopsies performed in the center of the developing striatum in acutely sectioned 300 Âµm coronal slices of the brain at postnatal day 0 (P0). Sections were matched rostro-caudally between wild type and null mutant tissue, and fiduciary landmarks were used to assure reproducible microdissection of comparable regions. RNA was extracted using the StrataPrep Total RNA Mini Kit (Stratagene, La Jolla, CA), and RNA quality was assayed using a bioanalyzer (Agilent Technologies, Paola Alto, CA). To ensure reproducibility and biological significance, microarrays were performed with RNA samples from three independent wild type, one heterozygote, and four Ctip2-/- mice (biological replicates). Microarray data were normalized using the RMA function within Bioconductor (Irizarry et al., 2003). Statistical significance of gene expression differences between wild type and knockout was determined using Statistical Analysis of Micrarrays (SAM) (Tusher et al., 2001). Using a SAM d-score cutoff of > 2 or < -2, we selected the 153 most significant genes and further analyzed them to identify a smaller set of genes of potentially high biological relevance.

Project description:The striatum is the main input structure of the basal ganglia, receiving information from the cortex and the thalamus and consisting of D1- and D2- medium spiny neurons (MSNs). D1-MSNs and D2-MSNs are essential for motor control and cognitive behaviors and have implications in Parkinson’s Disease. In the present study, we demonstrated that Sp9 positive progenitors produced both D1-MSNs and D2-MSNs and that Sp9 expression was rapidly downregulated in postmitotic D1-MSNs. Furthermore, we found that sustained Sp9 expression in lateral ganglionic eminence (LGE) progenitor cells and their descendants led to promoting D2-MSNs identity and repressing D1-MSNs identity during striatal development. As a result, sustained Sp9 expression resulted in an imbalance between D1-MSNs and D2-MSNs in the mouse striatum. In addition, the fate-changed D2 like-MSNs survived normally in adulthood. Taken together, our finding supported that Sp9 was sufficient to promote D2-MSNs identity and repress D1-MSNs identity, and Sp9 was a negative regulator of D1-MSNs fate. The striatum is the main input structure of the basal ganglia, receiving information from the cortex and the thalamus and consisting of D1- and D2- medium spiny neurons (MSNs). D1-MSNs and D2-MSNs are essential for motor control and cognitive behaviors and have implications in Parkinson’s Disease. In the present study, we demonstrated that Sp9 positive progenitors produced both D1-MSNs and D2-MSNs and that Sp9 expression was rapidly downregulated in postmitotic D1-MSNs. Furthermore, we found that sustained Sp9 expression in lateral ganglionic eminence (LGE) progenitor cells and their descendants led to promoting D2-MSNs identity and repressing D1-MSNs identity during striatal development. As a result, sustained Sp9 expression resulted in an imbalance between D1-MSNs and D2-MSNs in the mouse striatum. In addition, the fate-changed D2 like-MSNs survived normally in adulthood. Taken together, our finding supported that Sp9 was sufficient to promote D2-MSNs identity and repress D1-MSNs identity, and Sp9 was a negative regulator of D1-MSNs fate.

Project description:Schizophrenia is a chronic mental illness that is among the world’s top twenty causes of years lost to disability according to the global burden of disease 2019 (10.1016/S0140-6736(20)30925-9). Positive symptoms, including hallucinations and delusions in schizophrenia, often improved with conventional antipsychotic medication, which exerts its therapeutic effects mainly by antagonizing the dopamine D2 receptors. Haloperidol was one of the first antipsychotics to be approved by the FDA, and it is since then widely used for the treatment of psychotic disorders including schizophrenia. Despite its high affinity for dopamine D2 receptors, it has been shown that haloperidol interacts with other receptors, such as dopamine D3 and D4 receptors, α-adrenergic receptor 1 and to some extent 5HT2A. Dopaminergic dysfunction is known for decades to be involved in the pathophysiology of schizophrenia, but only recently has the striatum been implicated in such devasting disorder. The dorsal striatum is a brain region involved in motor, cognitive and motivational functions, highly impacted by antipsychotic drugs. Particularly, it is well-recognized that chronic haloperidol administration has a tremendous impact on striatal synaptic plasticity, by changing the volume of dorsal striatum, the number of striatal neurons and the synaptic morphology, both in humans and rodents. Despite the overwhelming evidence correlating chronic haloperidol administration with striatum alterations, so far, the exact striatal synaptic mechanism by which haloperidol exerts its beneficial effects remains unclear. Although dopamine D2 receptor blockade can be achieved within hours after haloperidol administration, the onset of action is delayed by weeks. Thus, it is crucial to better understand the neuronal mechanism behind the delayed clinical effects of haloperidol to improve the treatment outcome. Using proteomic analysis and whole-cell patch-clamp recordings (Figure 1), we demonstrate for the first time a possible mechanism by which haloperidol may be contributing to its beneficial long-term therapeutic effect. Specifically, we demonstrate that modulation of D2-MSNs by chronic haloperidol administration leads to a slow remodeling of D1-neurons that may be responsible for its positive therapeutic effects.

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Expression data from wild type and Ctip2-/- (Bcl11b) mutant mouse striatum at P0

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