Project description:Neuronal loss in the substantia nigra pars compacta (SNpc) in Parkinson disease (PD) is not uniform, as dopamine neurons from the ventral tier are lost more rapidly than those of the dorsal tier. Identifying the intrinsic differences that account for this differential vulnerability may provide a key for developing new treatments for PD. Here, we compared the RNA-sequenced transcriptomes of ~100 laser captured microdissected SNpc neurons from each tier from 7 healthy controls. Expression levels of dopaminergic markers were similar across the tiers, whereas markers specific to the neighboring ventral tegmental area were virtually undetected. After accounting for unwanted sources of variation, we identified 106 differentially expressed genes (DEGs) between the SNpc tiers. The genes higher in the dorsal/resistant SNpc tier neurons displayed coordinated patterns of expression across the human brain, their protein products had more interactions than expected by chance, and they demonstrated evidence of functional convergence. No significant shared functionality was found for genes higher in the ventral/vulnerable SNpc tier. Surprisingly but importantly, none of the identified DEGs was among the familial PD genes or genome-wide associated loci. Finally, we found some DEGs in opposite tier orientation between human and analogous mouse populations. Our results highlight functional enrichments of vesicular trafficking, ion transport/homeostasis and oxidative stress genes showing higher expression in the resistant neurons of the SNpc dorsal tier. Furthermore, the comparison of gene expression variation in human and mouse SNpc populations strongly argues for the need of human-focused omics studies
Project description:Ventral midbrain (VM) dopaminergic progenitor cells derived from human pluripotent stem cells have the potential to replace endogenously lost dopamine neurons and are currently in preclinical and clinical development for treatment of Parkinson’s Disease (PD). However, one main challenge in the quality control of the cells is that rostral and caudal VM progenitors are extremely similar transcriptionally though only the caudal VM cells give rise to dopaminergic neurons with functionality in PD. Therefore, it is critical to develop assays which can rapidly and reliably discriminate rostral from caudal VM cells during clinical manufacturing. Here, we applied shotgun proteomics to search for novel secreted biomarkers specific for caudal VM progenitors compared to rostral VM progenitors and validated key hits by ELISA. From this, we identified novel secreted markers (CPE, LGI1 and PDGFC) significantly enriched in caudal versus rostral VM progenitor cultures, whereas the markers CNTN2 and CORIN were significantly enriched in rostral VM cultures. With this data, we suggest and test in clinical grade samples a panel of coupled ELISA assays that can be applied as a quality control tool for assessing the correct patterning of cells during clinical manufacturing.
Project description:Midbrain dopamine (mDA) neurons comprise a diverse group of cells with unique innervation targets and functions. This is illustrated by the selective sensitivity of mDA neurons of the substantia nigra compacta (SNc) in patients with Parkinson’s disease, while those in the ventral tegmental area (VTA) are relatively spared. Here we used single nuclei RNA sequencing (snRNA-seq) of approximately 70,000 mouse midbrain cells to build a high-resolution atlas of mouse mDA neuron diversity at the molecular level. The results showed that differences between mDA neuron groups could best be understood as a continuum without sharp differences between subtypes. Thus, we assigned mDA neurons to several “territories” and “neighborhoods” within a shifting gene expression landscape where boundaries are gradual rather than discrete. Based on the enriched gene expression patterns of these territories and neighborhoods, we were able to localize them in the adult mouse midbrain. Moreover, because the underlying mechanisms for the variable sensitivities of diverse mDA neurons to pathological insults are not well understood, we analyzed surviving neurons after partial 6-hydroxydopamine (6-OHDA) lesions to unravel gene expression patterns that correlate with mDA neuron vulnerability and resilience. Together, this atlas provides a basis for further studies on the neurophysiological role of mDA neurons in health and disease.
Project description:Significant efforts are ongoing to develop refined differentiation protocols to generate midbrain DA neurons from pluripotent stem cells (PSCs) for application in disease modeling, diagnostics, drug screening, and cell-based therapies for Parkinson’s Disease. An increased understanding of the timing and molecular mechanisms promoting the generation of distinct subtypes of midbrain DA during normal development will be essential for guiding future efforts to precisely generate molecularly defined and subtype-specific DA neurons from pluripotent stem cells. In this study, we used droplet-based single-cell RNA sequencing (scRNA-seq) to transcriptionally profile fetal DA neurons from human embryos at different stages of ventral midbrain (VM) development (6, 8, and 11 weeks post-conception) and primary fetal 3D cultures thereof that allowed differentiation and functional maturation of human DA neurons. This approach allowed us to define the molecular identities of distinct human DA progenitors and neurons at single-cell resolution and construct developmental trajectories of cell types in the developing fetal VM. Overall, these findings provide a unique transcriptional profile of developing human fetal VM and functionally mature human DA neurons, which can be used to guide stem cell-based therapies and disease modeling approaches in PD.
Project description:The circadian nature of mood and its dysfunction in affective disorders is well recognized, but the underlying molecular mechanisms are still unclear. We showed that the circadian nuclear receptor REV-ERBa, which is associated with bipolar disorder, impacts midbrain dopamine production and mood-related behavior in mice. Genetic deletion of the Rev-erba gene or pharmacological inhibition of REV-ERBa activity in the ventral midbrain induced mania-like behavior in association with a central hyperdopaminergic state. We used microarrays to identify differentially expressed genes in the ventral midbrains of wild-type (WT) and Rev-erba knock-out (RKO) mice.
Project description:Pitx3 is a transcription factor that is expressed in all midbrain dopaminergic (mDA) neurons during early development, but later becomes restricted in dopaminergic subsets of substantia nigra compacta (SNc) and of the ventral tegmental are (VTA) that are vulnerable to neurodegenerative stress (MPTP, 6-OHDA, rotenone, Parkinson's disease). Overall, in mice, Pitx3 is required for developmental survival of ventral SNc neurons and for postnatal survival of VTA neurons (after postnatal day 40). With the aim of determining the gene networks that distinguish Pitx3-vulnerable (Pitx3-positive) from Pitx3-resistant (Pitx3-negative) subsets of SNc and VTA, we performed a comparison at the transcriptome level between FAC-sorted mDA neurons of SNc and VTA that were obtained from wild-type and Pitx3-/- newborn mice. The latter mice have already lost the majority of their TH+Calb1- mDA neurons of ventral SNc (Pitx3-dependent), but their TH+Calb1+ neurons of dorsal SNc (Pitx3-independent), including all of VTA neurons (50% are Pitx3-dependent and 50% Pitx3-independent), are unaffected by Pitx3 deletion. At postnatal day 40, Pitx3-/- mice display a marked loss of dopaminergic subsets of VTA that normally co-express Pitx3 and Calb1 (Pitx3-dependent neurons of VTA).
Project description:The circadian nature of mood and its dysfunction in affective disorders is well recognized, but the underlying molecular mechanisms are still unclear. We showed that the circadian nuclear receptor REV-ERBa, which is associated with bipolar disorder, impacts midbrain dopamine production and mood-related behavior in mice. Genetic deletion of the Rev-erba gene or pharmacological inhibition of REV-ERBa activity in the ventral midbrain induced mania-like behavior in association with a central hyperdopaminergic state. We used microarrays to identify differentially expressed genes in the ventral midbrains of wild-type (WT) and Rev-erba knock-out (RKO) mice. Male RKO and WT mice (10-15 weeks of age) were maintained in a C57BL/6J background. Mice were housed in temperature-controlled (22-23ºC) quarters under a 12-h light-dark (LD) photoperiod (lights on at 8:00 a.m.). After entrainment for >10 days under LD conditions, mice were kept in constant darkness (DD) for 2 days starting at lights-off time. On the third day, mice were sacrificed at indicated time points by cervical dislocation.
Project description:The hippocampus - one of the most studied brain regions – is a key target of the stress response and vulnerable to the detrimental effects of stress. Although its intrinsic organization is highly conserved throughout its long dorsal-ventral axis, the dorsal hippocampus is linked to spatial navigation and memory formation, whereas the ventral hippocampus is linked to emotional regulation. Here, we provide the first combined transcriptomic and proteomic profiling that reveals striking differences between dorsal and ventral hippocampus. Using various acute stress challenges we demonstrate that both regions display very distinct molecular responses, and that the ventral hippocampus is particularly responsive to the effects of stress. We demonstrate that separately analyzing dorsal and ventral hippocampus greatly increases the ability to detect region-specific stress effects, and we identify an epigenetic network, which is specifically sensitive to acute stress in the ventral hippocampus.
Project description:Human pluripotent stem cells (hPSCs) are a promising source of cells for applications in regenerative medicine. Directed differentiation of hPSCs into specialized cells such as spinal motoneurons or midbrain dopamine (DA) neurons has been achieved. However the effective use of hPSCs for cell therapy has lagged far behind. While mouse PSC-derived DA neurons have shown efficacy in models of Parkinson’s disease, DA neurons derived from human PSCs generally display poor in vivo performance. There are also considerable safety concerns for hPSCs related to their potential for teratoma formation or neural overgrowth. Here we present a novel floor plate-based strategy for the derivation of human DA neurons that efficiently engraft, suggesting that past failures were due to incomplete specification rather than a specific vulnerability of the cells. Midbrain floor plate precursors are derived from hPSCs in days following exposure to small molecule activators of sonic hedgehog (SHH) and canonical WNT signaling. Engraftable midbrain DA neurons are obtained by day 25 and can be maintained in vitro for several months. Extensive in vitro molecular profiling, biochemical and electrophysiological data define developmental progression and confirm identity of hPSC-derived midbrain DA neurons. In vivo survival and function is demonstrated in PD animal models in three host species. Long-term engraftment in 6-OHDA-lesioned mouse and rats demonstrates robust survival of midbrain DA neurons, complete restoration of amphetamine-induced rotation behavior and improvements in tests of forelimb use and akinesia. Finally, scalability is demonstrated by transplantation into Parkinsonian monkeys. Excellent DA neuron survival, function and lack of neural overgrowth in the three animal models tested indicate considerable promise for the development of cell based therapies in PD. Differentiated hESC with three conditions (LSB, LSB/S/F8, LSB/S/F8/CHIR) were subjected to RNA extraction in specific timepoint (day 0, 1, 3, 5, 7, 11, 13, 25) and hybridization on Illumina microarrays. Each sample has 3 or 4 biological repeats. Based on previous study* of dual SMAD inhibition neural induction, we developed new midbrain dopamine neuron protocol. It depends on time specific treatment of below factors (LSB/S/F8/CHIR): L (LDN193189 (BMP inhibitor) , day 0-11), SB (SB431542 (TGF-b signal inhibitor), day 0-5), S (SHH + Purmorphamine (Smo agonist), day 1-7), F8 (FGF8, day 1-7) and CHIR (CHIR99021 (GSK3b inhibitor), day 3-13) LSB and LSB/S/F8 are limited control conditions of dual SMAD only (LSB) or traditional patterning with Sonic and FGF (LSB/S/F8) *Chambers,S.M. et al. Highly efficient neural conversion of human ES and iPS cells by dual inhibition of SMAD signaling. Nat. Biotechnol. 27, 275-280 (2009).