Project description:Background: Nephron progenitor cells (NPCs) undergo a stepwise process to generate all mature nephron structures. Mesenchymal to epithelial transition (MET) is considered a multi-step process of NPC differentiation to ensure progressive establishment of new nephrons. However, despite this important role, to date, no marker for NPCs undergoing MET in the nephron exists. Results: Here, we identify LGR6 as a NPC marker, expressed in very early cap mesenchyme, pre-tubular aggregates, renal vesicles and in segments of S-shaped bodies, following the trajectory of MET. By using a lineage tracing approach in embryonic explants in combination with confocal imaging and single-cell RNA sequencing, we provide evidence for the multiple fates of LGR6+ cells during embryonic nephrogenesis. Moreover, by using long-term in vivo lineage tracing, we show that postnatal LGR6+ cells are capable of generating the multiple lineages of the nephrons. Conclusion: Given the profound early mesenchymal expression and MET signature of LGR6+ cells, together with the lineage tracing of mesenchymal LGR6+ cells, we conclude that LGR6+ cells contribute to all nephrogenic segments by undergoing MET. LGR6+ cells can therefore be considered an early committed NPC population during embryonic and postnatal nephrogenesis with potential regenerative capability.
Project description:Mammalian epidermis consists of three self-renewing compartments: the hair follicle, sebaceous gland and interfollicular epidermis. We generated knock-in alleles of murine Lgr6, a close relative to the Lgr5 stem cell gene. Lgr6 was expressed in the earliest embryonic hair placodes. In adult hair follicles, Lgr6+ cells resided in a previously uncharacterized region directly above the follicle bulge. They expressed none of the known bulge stem cell markers. Prenatal Lgr6+ cells established the hair follicle, sebaceous gland and interfollicular epidermis. Postnatally, Lgr6+ cells generated sebaceous gland and interfollicular epidermis, while contribution to hair lineages gradually diminished with age. Adult Lgr6+ cells executed long-term wound repair, including the formation of new hair follicles. We conclude that Lgr6 marks the most primitive epidermal stem cell. For the Lgr5 and Lgr6 stem cell comparison RNA was isolated from sorted GFPhi cell fractions of dorsal skin from Lgr5-EGFP-ires-CreERT2 mice and Lgr6-EGFP-ires-CreERT2, respectively (3 mice per group per sort).
Project description:Mammalian epidermis consists of three self-renewing compartments: the hair follicle, sebaceous gland and interfollicular epidermis. We generated knock-in alleles of murine Lgr6, a close relative to the Lgr5 stem cell gene. Lgr6 was expressed in the earliest embryonic hair placodes. In adult hair follicles, Lgr6+ cells resided in a previously uncharacterized region directly above the follicle bulge. They expressed none of the known bulge stem cell markers. Prenatal Lgr6+ cells established the hair follicle, sebaceous gland and interfollicular epidermis. Postnatally, Lgr6+ cells generated sebaceous gland and interfollicular epidermis, while contribution to hair lineages gradually diminished with age. Adult Lgr6+ cells executed long-term wound repair, including the formation of new hair follicles. We conclude that Lgr6 marks the most primitive epidermal stem cell.
Project description:Stem cells support the lifelong maintenance of adult organs but their specific roles during injury are poorly understood. Here, we demonstrate that Lgr6 marks a regionally restricted population of epidermal stem cells that interact with nerves and specialize in wound re-epithelialization. Diphtheria toxin-mediated ablation of Lgr6 stem cells delays wound healing, and skin denervation phenocopies this effect. Using intravital imaging to capture stem cell dynamics after injury, we show that wound re-epithelialization by Lgr6 stem cells is diminished following the loss of nerves. This induces the recruitment of other stem cell populations, including hair follicle stem cells, which partially compensate to mediate the wound closure. Single-cell lineage tracing and gene expression analysis reveal that the fate of Lgr6 stem cells is shifted towards differentiation following the loss of their niche. We conclude that Lgr6 epidermal stem cells are primed for injury response and interact with nerves to regulate their fate
Project description:p53 limits the self-renewing ability of a variety of stem cells. Here, contrary to its classical role in restraining cell proliferation, we demonstrate a divergent function of p53 in maintenance of self-renewal of the nephron progenitor population in the embryonic mouse kidney. p53-null nephron progenitor cells (NPC) exhibit progressive loss of the self-renewing progenitor niche in the cap mesenchyme, identified by Cited1 and Six2 expression, and loss of cap integrity. Nephron endowment is regulated by NPC availability and their differentiation to nephrons. Quantitatively, the Six2p53-/- cap has 30% fewer Six2GFP+ cells. While the apoptotic index is unchanged the proliferation index is significantly lower, in accordance with cell cycle analysis data showing less mutant Six2p53-/-;GFP+ cells in S and G2/M phases in comparison to Six2p53+/+;GFP+ cells. The mutant kidneys also show nephron deficit and decreased Fgf8 expression. To investigate the underlying changes in gene expression in the cap mesenchyme that contribute to the Six2p53-/- phenotype, we utilized RNA-Seq for transcriptome comparison. Top biological processes affected by p53 loss are development and morphogenesis, cell adhesion/migration, cell survival and metabolism. Cells from the mutant CM showed increased cellular ROS levels as well as deregulated expression of energy metabolism and mitochondrial genes suggesting metabolic dysfunction. Adhesion defects are visualized by decreased immunostaining of adhesion marker NCAM, and may possibly contribute to the differentiation defect as well. Altogether our data suggest a novel role for p53 in enabling self-renewal of the NPC and preservation of the progenitor niche, and thus regulating nephron endowment. mRNA profiles of wild-type (WT) and conditional p53 knockout (KO) of Six2+ mouse nephron progenitor cells (NPC) at embryonic day 15.5
Project description:Analysis of induced nephron progenitor cells from female/male urine cells (iNPC-F/INPC-M) by defined transcription factors vs. ESC derived nephron progenitor cell (ESC-NPC_H9/ESC-NPC_BG01) and female/male urine cells (UC-F/UC-M). Results provide insight into molecular similarities between induced nephron progenitor cells and human ESC derived nephron progenitor cell
Project description:During development, nephron progenitor forming one million nephrons, a functional unit in the kidney. However, nephron progenitor ceases before birth in human when they terminally differentiated to the nephron. Our lab established the method for induction of nephron progenitors from mouse Embryonic Stem (ES) cells and/or human induced Pluripotent Stem Cells (iPSCs) (Taguchi et al., Cell Stem Cell. 2014, 2017). For application of induced nephron progenitors to regenerative medicine, a large number of cells are required such as disease modeling and drug screening. To selectively propagate human iPS-derived nephron progenitors in vitro in an undifferentiated state, we developed SIX2-GFP iPS line and optimized culture condition of induced nephron progenitors by modifying our previously developed condition (Tanigawa et al., Cell Rep. 2016). To understand how whole gene expression profiles of human iPS-derived nephron progenitor cells are changed during culture, we isolated nephron progenitor cells by FACS and cultured in our defined culture condition. Purified RNAs from cultured cells at day 7 or un-cultured nephron progenitor cells were analyzed by RNA-seq.
Project description:RNA sequencing was performed on sorted populations of Lgr6-positive and Lgr6-negative keratinocytes from the interfollicular epidermis and the hair follicle/sebaceous gland, in order to determine the compartment-specific expression signatures of Lgr6+ progenitor cells.