Project description:L-3,4-dihydroxyphenylalanine (levodopa) treatment is the major pharmacotherapy for Parkinson's disease. However, almost all patients receiving levodopa eventually develop debilitating involuntary movements (dyskinesia). While it is known that striatal spiny projection neurons (SPNs) are involved in the genesis of this movement disorder, the molecular basis of dyskinesia is not understood. In this study, we identify distinct cell-type-specific gene expression changes that occur in sub-classes of SPNs upon induction of a parkinsonian lesion followed by chronic levodopa treatment. We identify several hundred genes whose expression is correlated with levodopa dose, many of which are under the control of AP-1 and ERK signaling. In spite of homeostatic adaptations involving several signaling modulators, AP-1-dependent gene expression remains highly dysregulated in direct pathway SPNs (dSPNs) upon chronic levodopa treatment. We also discuss which molecular pathways are most likely to dampen abnormal dopaminoceptive signaling in spiny projection neurons, hence providing potential targets for antidyskinetic treatments in Parkinson's disease.
Project description:L-3,4-dihydroxyphenylalanine (levodopa) treatment is the major pharmacotherapy for Parkinson's disease. However, almost all patients receiving levodopa eventually develop debilitating involuntary movements (dyskinesia). While it is known that striatal spiny projection neurons (SPNs) are involved in the genesis of this movement disorder, the molecular basis of dyskinesia is not understood. In this study, we identify distinct cell-type-specific gene expression changes that occur in sub-classes of SPNs upon induction of a parkinsonian lesion followed by chronic levodopa treatment. We identify several hundred genes whose expression is correlated with levodopa dose, many of which are under the control of AP-1 and ERK signaling. In spite of homeostatic adaptations involving several signaling modulators, AP-1-dependent gene expression remains highly dysregulated in direct pathway SPNs (dSPNs) upon chronic levodopa treatment. We also discuss which molecular pathways are most likely to dampen abnormal dopaminoceptive signaling in spiny projection neurons, hence providing potential targets for antidyskinetic treatments in Parkinson's disease. To profile the cell-type-specific responses of striatal spiny projection neurons (SPNs) to striatal dopamine depletion, we conducted TRAP analysis of the two major classes of these neurons: dSPNs that express the dopamine receptor 1a (Drd1a), and iSPNs that express the dopamine receptor 2 (Drd2). To disrupt dopamine innervation to both of these SPN populations that reside in the striatum, we injected the neurotoxin 6-hydroxydopamine (6-OHDA), unilaterally, in the medial forebrain bundle (MFB) in hemizygous Drd1-TRAP and Drd2-TRAP adult (9-14 weeks) male mice (kept on a C57BL/6J genetic background). This lesion procedure causes nigral dopamine cell death within a few days, along with a widespread and near-complete loss of dopaminergic innervation to the entire dorsal striatum on one side of the brain (a hemiparkinsonian model). We first examined the effects of dopamine depletion alone, compared to a mock lesion (ascorbate / saline injected). We then examined the effects of chronic levodopa treatment upon the molecular profiles of dopamine- depleted dSPNs and iSPNs, with two dose regimens. The ‘high-dose’ L-DOPA regimen (3 mg/kg on days 1-3, followed by 6 mg/kg on days 4-9) was expected to induce severe dyskinesia in all MFB-lesioned mice. The low-dose L-DOPA regimen (1 mg/kg on days 1-3, followed by 2 mg/kg on days 4-9) was expected to reverse limb use asymmetry without causing conspicuous dyskinesias. To equalize the effects of stress and handling across all groups, including control groups, all mice were equally handled and thus received saline injections when not receiving levodopa injections. Each treatment group contained 7-10 replicates. TRAP-purified mRNAs from either Drd1a- or Drd2-expressing SPNs were reverse-transcribed, amplified, and used to interrogate Affymetrix 430_2.0 GeneChip microarrays.
Project description:The molecular mechanisms that underlie striatal development and organization remain largely unknown. Here, we show that Foxp1, a transcription factor strongly linked to autism and intellectual disability, regulates organizational features of striatal circuitry in a cell-type dependent fashion. Using single-cell RNA-sequencing, we examine the cellular diversity of the early postnatal striatum and demonstrate that Foxp1 specifies a subpopulation of indirect pathway spiny projection neurons (iSPNs) while maintaining the striosome-matrix architecture through molecular mechanisms mediated by direct pathway spiny projection neurons (dSPNs). Functionally, Foxp1 alters striatal projection patterns both cell-autonomously and non-autonomously. We connect these changes in striatal circuitry to distinct behavioral deficits relevant to phenotypes described in patients with FOXP1 loss-of-function mutations. These data reveal novel cell-type specific transcriptional mechanisms underlying distinct features of striatal circuitry and identify Foxp1 as a key regulator of striatal development
Project description:Dyskinesias are characterized by abnormal repetitive involuntary movements due to dysfunctional neuronal activity. Although levodopa-induced dyskinesia, characterized by tic-like abnormal involuntary movements, has no clinical treatment for Parkinson’s disease patients, animal studies indicate that Riluzole, which interferes with glutamatergic neurotransmission, can improve the phenotype. The rat model of levodopa-induced dyskinesia is a unilateral lesion with 6-hydroxydopamine in the medial forebrain bundle, followed by the repeated administration of levodopa. The molecular pathomechanism of levodopa-induced dyskinesia is still not deciphered, however implication of epigenetic mechanisms was suggested. In this study, we investigated the striatum for DNA methylation alterations under chronic levodopa treatment with or without co-treatment with Riluzole. Our data show that the lesioned and contralateral striata have nearly identical DNA methylation profiles. Chronic levodopa and levodopa+Riluzole treatments led to DNA methylation loss, particularly outside of promoters, in gene bodies and CpG poor regions. We observed that several genes involved in the levodopa-induced dyskinesia underwent methylation changes. Furthermore, the Riluzole co-treatment, which improved the phenotype, pinpointed specific methylation targets, with more than 20% methylation difference relative to levodopa treatment alone. These findings indicate potential new druggable targets for levodopa-induced dyskinesia.
Project description:Our study shows that deletion of the alternative splicing regulator PQBP1 in striatal progenitors resulted in defective striatal development due to impaired neurogenesis of spiny projection neurons (SPNs). Therefore, we further reveal that PQBP1 associated with components in splicing machinery by LC-MS/MS. These findings identify PQBP1 as a novel regulator in balancing striatal progenitor proliferation and differentiation.
Project description:Use of single-cell transcriptomics to measure how well medium spiny projection neurons, derived from human ESC, recapitulate human striatal development in vivo. This in vitro single-cell dataset was derived after exposing hESC lines (H9) to a novel striatal differentiation protocol and performing single-cell RNA-seq after 15 days and 25 days of differentiation.
Project description:The mechanisms by which mutant Huntingtin leads to neuronal cell death in Huntington’s disease are not fully understood. To gain new molecular insights, we used snRNA-Seq and TRAP to conduct transcriptomic analyses of striatal cell type-specific gene expression changes in human HD and mouse models of HD. In striatal spiny projection neurons we observe a release of mitochondrial RNA and a concomitant upregulation of innate immune signaling in spiny projection neurons. We observe that the released mtRNAs can directly bind to the innate immune sensor PKR. We highlight the importance of studying cell type-specific gene expression dysregulation in HD pathogenesis, and reveal that the activation of innate immune signaling in the most vulnerable HD neurons provides a novel framework to understand the basis of mHTT toxicity and raises new therapeutic opportunities.
Project description:We compared differential gene expression between Striatal tissue derived RNA isolated from Chronic Levodopa (L-DOPA) treated (L-Dopa methyl ester plus benserazide were given at 25 mg/kg and 6.25 mg/kg dose) - Parkinsonian and Dyskinetic Rats (LID Rats) for 8 days as compared to Parkinsonian Disease Control Rats (PD Control Rats). The hypothesis tested in the present study was that whether Inflammation has any role in Chronic Levodopa Induced Dyskinesia in Rats of Parkinson's disease model- as compared to Control Rats with Prakinson's disease by performing differential gene expression and pathway analyses.
Project description:This study addresses the molecular mechanisms underlying the action of subthalamic nucleus high frequency stimulation (STN-HFS) in the treatment of ParkinsonM-bM-^@M-^Ys disease and its interaction with levoDOPA (L-DOPA), focusing on the striatum. The objectives were 1) to identify the molecular signature of STN-HFS action at striatal level, associated with its efficient antiparkinsonian action, and 2) to investigate the molecular substrates of the interaction between the two treatments in order to evidence possible genes involved in dyskinesia. Striatal gene expression profile was assessed in rats with nigral DOPAmine neuron lesion, either treated or not, using agilent microarrays and qPCR verification. The treatments consisted in anti-akinetic STN-HFS (5 days), chronic L-DOPA treatment inducing dyskinesia (LIDs) or the combination of the two treatments that exacerbated LIDs. STN-HFS modulated 71 genes with functional or biochemical annotation, including genes sharing the GO terms regulation of growth, regulation of apoptosis, extracellular region. Ttr, Igf2, Sostdc1 and Nr4A3 (Nor-1), are among the 5 genes showing the highest specific upregulation. Down-regulated genes include Prkcd, Sirt5 and Bbc3. These results show that genes involved in neuroprotection and/or neurogenesis are key components of STN-HFS action in the striatum. STN-HFS and LDOPA treatment share very few common gene regulation features suggesting that the molecular substrates underlying their striatal action are mostly different. In addition to genes already reported to be associated with LIDs (Pdyn, Trh, Grm4/mGlu4, Cnr1/CB1), the comparison between DOPA and DOPA/STN-HFS identifies immunity-related genes: C1s, Rt1-Da and Irf7a, as potential players in L-DOPA side effects. Total RNA was extracted from striatal tissue from four groups of 3 animals bearing 6-hydroxyDOPAmine (6-OHDA)-induced lesion of the nigrostriatal DA pathway: lesion alone without any subsequent treatment (L), L-DOPA treatment for 19 days (D), STN-HFS for 5 days (S) and combination of L-DOPA and STN-HFS (DS).