Project description:How species-specific developmental timing is controlled is largely unknown. By following human embryonic stem cell (hESC) and mouse stem cell (mESC) differentiation to motor neurons through detailed RNA-sequencing time courses, we wish to find if there is a global scaling factor between species
Project description:How species-specific developmental timing is controlled is largely unknown. By following human embryonic stem cell (hESC) and mouse stem cell (mESC) differentiation to motor neurons through detailed RNA-sequencing time courses, we wish to find if there is a global scaling factor between species
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: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:Histone modifiers instruct cellular differentiation, yet how they achieve temporal precision remains enigmatic. Here we demonstrate that the H3K27 demethylase Kdm6b acts as a master epigenetic conductor and achieves timed gene activation by sequentially partnering with stage-specific transcription factors (TFs) in motor neuron (MN) differentiation. Genome-wide profiling revealed Kdm6b occupancy progressively shifted from proximal promoters to distal enhancers, along with increasing regulatory elements during maturation. At occupied sites, Kdm6b triggered rapid H3K27me3 loss with concurrent H3K27ac/H3K4me1 gain, establishing activation-competent chromatin. By integrating developmental TFs and histone modification landscapes, Kdm6b builds up the dynamic epigenetic choreography to precisely regulate MN developmental programs from early MN fate specification, intermediate cell differentiation and growth to later maturation. The ordered expression of developmental genes was compromised by stage-specific Kdm6b inhibition. Our work resolves how a single epigenetic regulator achieves temporal precision in driving stepwise MN development, with broad implications for neurodevelopment and diseases.
Project description:Human and mouse cells undergoing in vitro motor neurogenesis were sampled at high temporal resolution to identify species' differences in the progenitor pools that give rise to disproportionate timescale changes of motor neurogenesis between human and mouse.