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: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.
Project description:Histone modifiers are crucial for instructing multiple-stage cellular differentiation, yet the mechanisms underlying their temporal precision remain enigmatic. Here, we demonstrate that the H3K27 demethylase Kdm6b acts as an epigenetic regulator, coordinating stepwise motor neuron (MN) differentiation through sequential partnerships with stage-specific transcription factors (TFs). Genome-wide profiling reveals a progressive gain in Kdm6b occupancy, especially at distal regulatory elements, as differentiation proceeds. Kdm6b dynamically shapes chromatin landscapes by coordinating H3K27me3 removal with H3K27ac and H3K4me1 acquisition, thereby enabling timed gene activation from MN specification to maturation. Stage-specific inhibition of Kdm6b compromised the ordered expression of developmental genes. Mechanistically, Kdm6b interacts with temporal TFs over time to ensure precise transcriptional control and MN differentiation. Our work elucidates how a single epigenetic regulator achieves temporal fidelity in driving stepwise MN development, and exemplifies a mechanistic insight into epigenetic regulation in determining developmental timing, with broad implications for understanding neurodevelopment and related diseases.