Project description:We have generated human induced Pluripotent Stem cells (hiPSc) from amyotrophic lateral sclerosis (ALS, motor neuron disease) patients, using Sendai virus-mediated delivery of reprogramming factors. hiPSc lines have been screened using SNP array to assess chromosomal stability (alongside the fibroblast lines from which they derived), and validation of the pluripotency of the hiPSc lines is provided by Pluritest assessment of transcriptome datasets, prior to differentiation to motor neuron cultures and downstream functional assays. Mutihac R., Scaber J., Lalic T., Ababneh N., Vowles, J., Fletcher-Jones A., Douglas A.G.L., Browne C., Nakanishi M., Turner M., Wade-Martins R., Cowley S.A. and Talbot K. Altered ER calcium homeostasis and stress granule formation in iPSC-derived motor neurons from ALS/FTD patients with C9orf72 expansions. Submitted
Project description:Amyotrophic lateral sclerosis is a fatal neurodegenerative disorder primarily characterized by motor neuron degeneration with additional involvement of non-neuronal cells, in particular, microglia. In our previous work, we have established protocols for the differentiation of iPSC-derived spinal motor neurons and microglia. Here, we combine both cell lineages and establish a novel co-culture of iPSC-derived motor neurons and microglia, which is compatible with motor neuron identity and function. Co-cultured microglia express key microglial markers and transcriptomically resemble primary human microglia, have highly dynamic ramifications, are phagocytic, release various cytokines and respond to stimulation. Further, they express key amyotrophic lateral sclerosis-associated genes and release disease-relevant biomarkers. This novel and authentic human model system facilitates the study of physiological motor neuron-microglia crosstalk and permits the investigation of non-cell-autonomous phenotypes in amyotrophic lateral sclerosis.
Project description:We have generated human induced Pluripotent Stem cells (hiPSc) from amyotrophic lateral sclerosis (ALS, motor neuron disease) patients, using Sendai virus-mediated delivery of reprogramming factors. hiPSc lines have been screened using SNP array to assess chromosomal stability (alongside the fibroblast lines from which they derived), and validation of the pluripotency of the hiPSc lines is provided by Pluritest assessment of transcriptome datasets, prior to differentiation to motor neuron cultures and downstream functional assays. Mutihac R., Scaber J., Lalic T., Ababneh N., Vowles, J., Fletcher-Jones A., Douglas A.G.L., Browne C., Nakanishi M., Turner M., Wade-Martins R., Cowley S.A. and Talbot K. Altered ER calcium homeostasis and stress granule formation in iPSC-derived motor neurons from ALS/FTD patients with C9orf72 expansions. Submitted
Project description:The motor neuron (MN)–hexamer complex consisting of LIM homeobox 3, Islet-1, and nuclear LIM interactor is a key determinant of motor neuron specification and differentiation. To gain insights into the transcriptional network in motor neuron development, we performed a genome-wide ChIP-sequencing analysis and found that the MN–hexamer directly regulates a wide array of motor neuron genes by binding to the HxRE (hexamer response element) shared among the target genes. Interestingly, STAT3-binding motif is highly enriched in the MN–hexamer–bound peaks in addition to the HxRE. We also found that a transcriptionally active form of STAT3 is expressed in embryonic motor neurons and that STAT3 associates with the MN–hexamer, enhancing the transcriptional activity of the MN–hexamer in an upstream signal-dependent manner. Correspondingly, STAT3 was needed for motor neuron differentiation in the developing spinal cord. Together, our studies uncover crucial gene regulatory mechanisms that couple MN–hexamer and STAT-activating extracellular signals to promote motor neuron differentiation in vertebrate spinal cord. To explain our experimental scheme briefly, we are interested in finding target sites for the dimer of transcription factors Isl1 and Lhx3. To mimic the biological activity of Isl1/Lhx3 dimer, we made Isl1-Lhx3 fusion and found that Isl1-Lhx3 has a potent biological activity in multiple systems (i.e. generation of ectopic motor neurons). Then we made ES cell line that induces Flag-tagged Isl1-Lhx3 expression upon Dox treatment. These *mouse* ES cells differentiate to motor neurons (iMN-ESCs) when treated with Dox following EB formation. To identify genomic binding sites of Isl1-Lhx3 (Flag-tagged), we performed ChIP with Flag antibody (pull down of Flag-Isl1-Lhx3) in ES cells treated with Dox. ChIP with Flag antibody in ES cells treated with vehicle (no Dox) was done as a negative control in parallel, and sequenced along with +Dox sample. We have done these experiments twice (two sets).
Project description:Spinal muscular atrophy (SMA) is characterized by low levels of survival motor neuron (SMN) protein and loss of motor neurons (MN); however, the underlying mechanism that links SMN deficiency to selective motor neuronal dysfunction is still largely unknown. We present here, for the first time, a comprehensive quantitative mass spectrometry study that covers the development of iPSC-derived MNs from both healthy individuals and SMA patients. We show an altered proteomic signature in SMA already at early stages during MN differentiation, associated with ER to Golgi transport, mRNA splicing and protein ubiquitination, in line with known SMA phenotypes. These alterations in the SMA proteome increase further towards later stages of MN differentiation. In addition, we find differences in altered protein expression between SMA patients, which however, have similar biological functions. Finally, we highlight several known SMN-binding partners as well as proteins associated with ubiquitin-mediated proteolysis and evaluate their expression changes during MN differentiation. Altogether, our work provides a rich resource of molecular events during early stages of MN differentiation, containing potentially therapeutically interesting protein expression profiles for SMA.
Project description:The motor neuron (MN)–hexamer complex consisting of LIM homeobox 3, Islet-1, and nuclear LIM interactor is a key determinant of motor neuron specification and differentiation. To gain insights into the transcriptional network in motor neuron development, we performed a genome-wide ChIP-sequencing analysis and found that the MN–hexamer directly regulates a wide array of motor neuron genes by binding to the HxRE (hexamer response element) shared among the target genes. Interestingly, STAT3-binding motif is highly enriched in the MN–hexamer–bound peaks in addition to the HxRE. We also found that a transcriptionally active form of STAT3 is expressed in embryonic motor neurons and that STAT3 associates with the MN–hexamer, enhancing the transcriptional activity of the MN–hexamer in an upstream signal-dependent manner. Correspondingly, STAT3 was needed for motor neuron differentiation in the developing spinal cord. Together, our studies uncover crucial gene regulatory mechanisms that couple MN–hexamer and STAT-activating extracellular signals to promote motor neuron differentiation in vertebrate spinal cord.
Project description:Generic spinal motor neuron identity is specified by cooperative binding of selector transcription factors to motor neuron specific enhancers. Whether these enhancers remain active to maintain the motor neuron expression program following downregulation of selector factors in maturing motor neurons remains unknown. We demonstrate that enhancers established by selector genes are highly transient during motor neuron differentiation. The chromatin immunoprecipitation-exonuclease (ChIP-exo) assay reveals that Isl1 is anchored to nascent motor neuron enhancers through protein-protein interaction. Stage-specific recruitment of transcription factors correlates with active enhancer marks. The majority of genes contain distinct early and late enhancers suggesting that the motor neuron expression program is maintained by a dynamic regulatory landscape.