Label-free detection of neuronal differentiation in cell populations using high-throughput live-cell imaging of PC12 cells.
ABSTRACT: Detection of neuronal cell differentiation is essential to study cell fate decisions under various stimuli and/or environmental conditions. Many tools exist that quantify differentiation by neurite length measurements of single cells. However, quantification of differentiation in whole cell populations remains elusive so far. Because such populations can consist of both proliferating and differentiating cells, the task to assess the overall differentiation status is not trivial and requires a high-throughput, fully automated approach to analyze sufficient data for a statistically significant discrimination to determine cell differentiation. We address the problem of detecting differentiation in a mixed population of proliferating and differentiating cells over time by supervised classification. Using nerve growth factor induced differentiation of PC12 cells, we monitor the changes in cell morphology over 6 days by phase-contrast live-cell imaging. For general applicability, the classification procedure starts out with many features to identify those that maximize discrimination of differentiated and undifferentiated cells and to eliminate features sensitive to systematic measurement artifacts. The resulting image analysis determines the optimal post treatment day for training and achieves a near perfect classification of differentiation, which we confirmed in technically and biologically independent as well as differently designed experiments. Our approach allows to monitor neuronal cell populations repeatedly over days without any interference. It requires only an initial calibration and training step and is thereafter capable to discriminate further experiments. In conclusion, this enables long-term, large-scale studies of cell populations with minimized costs and efforts for detecting effects of external manipulation of neuronal cell differentiation.
Project description:Human epidermal keratinocytes undergo tightly controlled program of cell differentiation, leading to the formation of cornified envelope. Primary keratinocytes in vitro, under calcium stimulation mimic the differentiation program observed in vivo. Analysis of the transcription profile of two cell population, such as proliferating cells and differentiating cells helps to discover new genes implicated in that process and to understand the mechanisms of regulation of the keratinocyte differentiation. Primary human keratinocytes were cultured under proliferating (Day 0, sub-confluent cells) and differentiating (seven days of high calcium medium) conditions. As a source of cells, we used normal skin from different body sites: back, foreskin, palmoplantar. RNA extracted from cultured primary human keratinocytes were isolated from five different donors. We compared the expression profiles of proliferating versus differentiating keratinocytes.
Project description:Transcriptome analysis of somatic stem cells and their progeny is fundamental to identify new factors controlling proliferation versus differentiation during tissue formation. Here we generated a combinatorial, fluorescent reporter mouse line to isolate proliferating neural stem cells, differentiating progenitors and newborn neurons that coexist as intermingled cell populations during brain development. Transcriptome sequencing revealed numerous novel long non-coding (lnc)RNAs and uncharacterized protein-coding transcripts identifying the signature of neurogenic commitment. Importantly, most lncRNAs overlapped neurogenic genes and shared with them a nearly identical expression pattern suggesting that lncRNAs control corticogenesis by tuning the expression of nearby cell fate determinants. We assessed the power of our approach by manipulating lncRNAs and protein-coding transcripts with no function in corticogenesis reported to date. This led to several evident phenotypes in neurogenic commitment and neuronal survival indicating that our study provides a remarkably high number of uncharacterized transcripts with hitherto unsuspected roles in brain development. Finally, we focussed on one lncRNA, Miat, whose manipulation was found to trigger pleiotropic effects on brain development and aberrant splicing of Wnt7b. Hence, our study suggests that lncRNA-mediated alternative splicing of cell fate determinants controls stem cell commitment during neurogenesis. M-bM-^@M-^\LncRNAs control neurogenesisM-bM-^@M-^] Aprea, Prenninger, Dori, Monasor, Wessendof, Zocher, Massalini, Ghosh, Alexopoulou, Lesche, Dahl, Groszer, Hiller, Calegari, The EMBO Journal (In Press) mRNA profiles of Proliferating Progenitors, Differentiating Progenitors and Neurons from lateral cortex of E14.5 mouse embryos. Each cell type in three biological replicates.
Project description:We newly identified skeletal muscle differentiation-associated miRNAs by comparing miRNA expression profile between C2C12 cell and Wnt4-overexpressing C2C12 cell. miR-487b, miR-3963 and miR-6412 are significantly down-regulated in differentiating C2C12 cells, and transfection of their mimics resulted in reduced expression of myogenic differentiation markers including Troponin T, myosin heavy chain fast and slow type. Single analysis for each condition (proliferating C2C12 cells, differentiating C2C12 cells, proliferating Wnt4-overexpressing C2C12 subline cells
Project description:Enteric nervous system (ENS) progenitor cells isolated from mouse and human bowel can be cultured in vitro as neurospheres which are aggregates of the proliferating progenitor cells, together with neurons and glial cells derived from them. To investigate the factors regulating progenitor cell proliferation and differentiation, we first characterised cell proliferation in mouse ENS neurospheres by pulse chase experiments using thymidine analogs. We demonstrate rapid and continuous cell proliferation near the neurosphere periphery, after which postmitotic cells move away from the periphery to become distributed throughout the neurosphere. While many proliferating cells expressed glial markers, expression of the neuronal markers ?-tubulin III (Tuj1) and nitric oxide synthase was detected in increasing numbers of post-mitotic cells after a delay of several days. Treatment of both mouse and human neurospheres with the ?-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) reduced expression of the transcription factors Hes1 and Hes5, demonstrating inhibition of Notch signaling. DAPT treatment also inhibited progenitor cell proliferation and increased the numbers of differentiating neurons expressing Tuj1 and nitric oxide synthase. To confirm that the cellular effects of DAPT treatment were due to inhibition of Notch signaling, siRNA knockdown of RBPj?, a key component of the canonical Notch signaling pathway, was demonstrated both to reduce proliferation and to increase neuronal differentiation in neurosphere cells. These observations indicate that Notch signaling promotes progenitor cell proliferation and inhibits neuronal differentiation in ENS neurospheres.
Project description:Spontaneous cytosolic calcium transients and oscillations have been reported in various tissues of nonhuman and human origin but not in human midbrain-derived stem cells. Using confocal microfluorimetry, we studied spontaneous calcium transients and calcium-regulating mechanisms in a human ventral mesencephalic stem cell line undergoing proliferation and neuronal differentiation. Spontaneous calcium transients were detected in a large fraction of both proliferating (>50%) and differentiating (>55%) cells. We provide evidence for the existence of intracellular calcium stores that respond to muscarinic activation of the cells, having sensitivity for ryanodine and thapsigargin possibly reflecting IP3 receptor activity and the presence of ryanodine receptors and calcium ATPase pumps. The observed calcium transient activity potentially supports the existence of a sodium-calcium antiporter and the existence of calcium influx induced by depletion of calcium stores. We conclude that the cells have developed the most important mechanisms governing cytosolic calcium homeostasis. This is the first comparative report of spontaneous calcium transients in proliferating and differentiating human midbrain-derived stem cells that provides evidence for the mechanisms that are likely to be involved. We propose that the observed spontaneous calcium transients may contribute to mechanisms involved in cell proliferation, phenotypic differentiation, and general cell maturation.
Project description:Understanding the dynamics of stem cell differentiation processes at the molecular level is a central challenge in developmental biology and regenerative medicine. Although the dynamic behaviors of differentiation regulators have been partially characterized, the architecture regulating the underlying molecular systems remains unclear.System-level analysis of transcriptional data was performed to characterize the dynamics of molecular networks in neural differentiation of stem cells. Expression of a network module of genes tightly co-expressed in mouse embryonic stem (ES) cells fluctuated greatly among cell populations before differentiation, but became stable following neural differentiation. During the neural differentiation process, genes exhibiting both differential variance and differential correlation between undifferentiated and differentiating states were related to developmental functions such as body axis development, neuronal movement, and transcriptional regulation. Furthermore, these genes were genetically associated with neuronal differentiation, providing support for the idea they are not only differentiation markers but could also play important roles in neural differentiation. Comparisons with transcriptional data from human induced pluripotent stem (iPS) cells revealed that the system of genes dynamically regulated during neural differentiation is conserved between mouse and human.The results of this study provide a systematic analytical framework for identifying key genes involved in neural differentiation by detecting their dynamical behaviors, as well as a basis for understanding the dynamic molecular mechanisms underlying the processes of neural differentiation.
Project description:Postnatal neural progenitors of the enteric nervous system are a potential source for future cell replacement therapies of developmental dysplasia like Hirschrpung’s disease. However, little is known about the molecular mechanisms driving the homeostasis and differentiation of this cell pool. In this work, we conducted Affymetrix gene chip experiments to identify differences in gene regulation between proliferation and early differentiation of enteric neural progenitors. We detected a total of 1333 regulated genes that were linked to different groups of cellular mechanisms involved in cell cycle, apoptosis, neural proliferation, and differentiation. As expected, we found a strong inhibition of cell cycle progression as well as an enhanced expression of neuronal and glial markers. We further found a marked inactivation of the canonical Wnt pathway during the beginning of cellular differentiation. Taken together, this data illustrated the various mechanisms taking place during the proliferation and early differentiation of enteric neural progenitor cells. We analyzed 2 groups with 3 samples each: 1 group consistent of cells proliferating für 11 days and 1 group of enterospheres proliferating for 9 days and differentiating for 2 days before RNA extraction
Project description:The proneural transcription factor Ascl1 coordinates gene expression in both proliferating and differentiating progenitors along the neuronal lineage. Here, we used a cellular model of neurogenesis to investigate how Ascl1 interacts with the chromatin landscape to regulate gene expression when promoting neuronal differentiation. We find that Ascl1 binding occurs mostly at distal enhancers and is associated with activation of gene transcription. Surprisingly, the accessibility of Ascl1 to its binding sites in neural stem/progenitor cells remains largely unchanged throughout their differentiation, as Ascl1 targets regions of both readily accessible and closed chromatin in proliferating cells. Moreover, binding of Ascl1 often precedes an increase in chromatin accessibility and the appearance of new regions of open chromatin, associated with de novo gene expression during differentiation. Our results reveal a function of Ascl1 in promoting chromatin accessibility during neurogenesis, linking the chromatin landscape at Ascl1 target regions with the temporal progression of its transcriptional program.
Project description:Neural stem cells (NSCs) are characterized by a capacity for self-renewal, differentiation into multiple neural lineages, all of which are considered to be promising components for neural regeneration. However, for cell-replacement therapies, it is essential to monitor the process of in vitro NSC differentiation and identify differentiated cell phenotypes. We report a real-time and label-free method that uses a capacitance sensor array to monitor the differentiation of human fetal brain-derived NSCs (hNSCs) and to identify the fates of differentiated cells. When hNSCs were placed under proliferation or differentiation conditions in five media, proliferating and differentiating hNSCs exhibited different frequency and time dependences of capacitance, indicating that the proliferation and differentiation status of hNSCs may be discriminated in real-time using our capacitance sensor. In addition, comparison between real-time capacitance and time-lapse optical images revealed that neuronal and astroglial differentiation of hNSCs may be identified in real-time without cell labeling.
Project description:The aim of this study was to investigate the effects of the antidepressants, escitalopram (0 nM, 145 nM, 290 nM, 1160 nM) and nortriptyline (0 nM, 267 nM, 534 nM, 1068 nM), in human hippocampal progenitor cells (HPC0A07/03C), either when proliferating or differentiating. We also considered expression changes occuring when proliferating cells switch to a differentiating state to form young neurons and astrocytes. Overall design: We assessed the genome-wide expression effects of neural stem cell differentiation. We compared 48 proliferating cell populations of the human hippocampal cell line with 48 cell populations after a 7-day differentiation protocol (1 sample dropped). We performed this analyses using data originally collected to compare the effects of antidepressants on proliferating/differentiating hippocampal progenitor cells; we regressed out the effects of antidepressant drug and dose, biological replicate and array batch in our analyses.