Project description:The appropriate development of myeloid progenitors into macrophages, the body’s professional phagocyte, is essential for organismal development, especially in mammals1. This dependence is exemplified by the observation that loss-of-function mutation in colony stimulating factor 1 receptor (CSF1R) results in multiple tissue abnormalities including osteopetrosis2. Despite this importance, little is known about the molecular and cell biological regulation of macrophage development. Here, we report the surprising finding that the chloride-sensing kinase With-no-lysine 1 (WNK1) is required for embryonic development of tissue-resident macrophages (TRMs). Myeloid-specific deletion of Wnk1 caused a dramatic loss of TRMs and subsequently disrupted organ development, induced systemic neutrophilia, and resulted in mortality between 3 and 4 weeks of age. Specifically, we observed that WNK1 absence stalled macrophage differentiation at the myeloid multipotent progenitor (MPP) stage, instead skewing MPP differentiation towards granulopoiesis. Mechanistically, the cognate CSF1R cytokine, macrophage-colony stimulating factor (M-CSF), triggers macropinocytosis in myeloid progenitors, which in turn induces phosphorylation of WNK1. Importantly, macropinocytosis by myeloid progenitors increases cytosolic chloride, which is directly sensed by WNK1. Perturbing chloride flux during macropinocytosis, inhibiting WNK1 chloride-sensing, and blocking macropinocytosis each skew progenitor differentiation from macrophage lineage to granulocyte lineage. Thus, we have uncovered a novel mechanism that links a cell biological process to a molecular circuit whereby WNK1 chloride-sensing and chloride flux act downstream of M-CSF-induced macropinocytosis by multipotent progenitors to ensure macrophage lineage fidelity.
Project description:The kinase protein WNK1 is highly expressed and phosphorylated in the testis, suggesting possible functions in regulating male fertility. Indeed, conditional pachytene-spermatocyte Wnk1 knock-out mice generated using the novel Wnt7a-Cre failed to produce functional sperm which resulted from the primary spermatogenic arrest during mid-pachynema. Global transcriptomic approaches identified ‘translation’ as one of the impacted events in Wnk1-depleted spermatocytes.
Project description:RNAseq was used to analyse transcriptional changes occuring in WNK1-expressing or WNK1-deficient DN3 thymocytes following injection of anti-CD3e
Project description:Polycomb Repressive Complex 2 (PRC2) catalyzes histone H3 lysine 27 tri-methylation, an epigenetic modification associated with gene repression. H3K27me3 is enriched at the promoters of a large cohort of developmental genes in embryonic stem cells (ESCs). Loss of H3K27me3 leads to a failure of ESCs to properly differentiate, which presents a major roadblock for dissecting the precise roles of PRC2 activity during lineage commitment. While recent studies suggest that loss of H3K27me3 leads to changes in DNA methylation in ESCs, how these two pathways coordinate to regulate gene expression programs during lineage commitment is poorly understood. Here, we analyzed gene expression and DNA methylation levels in several PRC2 mutant ESC lines that maintain varying levels of H3K27me3. We found that maintenance of intermediate levels of H3K27me3 allowed for proper temporal activation of lineage genes during directed differentiation of ESCs to spinal motor neurons (SMNs). However, genes that function to specify other lineages failed to be repressed, suggesting that PRC2 activity is necessary for lineage fidelity. We also found that H3K27me3 is antagonistic to DNA methylation in cis. Furthermore, loss of H3K27me3 leads to a gain in promoter DNA methylation in developmental genes in ESCs and in lineage genes during differentiation. Thus, our data suggest a role for PRC2 in coordinating dynamic gene repression while protecting against inappropriate promoter DNA methylation during differentiation. Embryonic Stem Cell (ESC) lines mutant for PRC2 core components Suz12 (Suz12GT and Suz12delta) and Eed (Eednull) were subjected to in vitro directed differentiation down the spinal motor neuron lineage. ESCs and day 5 differentiated cells from the three mutant lines and wild-type were used for Reduced Representation Bisulfite Sequencing (RRBS).