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Iain A. Drummond (PI)
Massachusetts General Hospital
To restore kidney function, filtering nephrons must connect to a tubule network to pass fluid. How cells rearrange and form new connections is not known. We are using the regenerating zebrafish kidney as a model to discover how tubule interconnections are made and to uncover signals that drive cell rearrangments required to "plumb" the kidney. Knowledge of these signals will be an important part of the molecular toolbox for growing new organs.
Grainger, Stephanie; Nguyen, Nicole; Richter, Jenna; Setayesh, Jordan; Lonquich, Brianna; Oon, Chet Huan; Wozniak, Jacob M.; Barahona, Rocio; Kamei, Caramai N.; Houston, Jack; Carrillo-Terrazas, Marvic; Drummond, Iain A.; Gonzalez, David; Willert, Karl; Traver, David. Nature Cell Biology. 21(6):721–730. June 2019.
Wnt signalling drives many processes in development, homeostasis and disease; however, the role and mechanism of individual ligand–receptor (Wnt–Frizzled (Fzd)) interactions in specific biological processes remain poorly understood. Wnt9a is specifically required for the amplification of blood progenitor cells during development. Using genetic studies in zebrafish and human embryonic stem cells, paired with in vitro cell biology and biochemistry, we determined that Wnt9a signals specifically through Fzd9b to elicit β-catenin-dependent Wnt signalling that regulates haematopoietic stem and progenitor cell emergence. We demonstrate that the epidermal growth factor receptor (EGFR) is required as a cofactor for Wnt9a–Fzd9b signalling. EGFR-mediated phosphorylation of one tyrosine residue on the Fzd9b intracellular tail in response to Wnt9a promotes internalization of the Wnt9a–Fzd9b–LRP signalosome and subsequent signal transduction. These findings provide mechanistic insights for specific Wnt–Fzd signals, which will be crucial for specific therapeutic targeting and regenerative medicine.
Gallegos, Thomas F.; Kamei, Caramai N.; Rohly, Michael; Drummond, Iain A. Dev Biol. June 2019.
The zebrafish kidney regenerates after injury by development of new nephrons from resident adult kidney stem cells. Although adult kidney progenitor cells have been characterized by transplantation and single cell RNA seq, signals that stimulate new nephron formation are not known. Here we demonstrate that fibroblast growth factors and FGF signaling is rapidly induced after kidney injury and that FGF signaling is required for recruitment of progenitor cells to sites of new nephron formation. Chemical or dominant negative blockade of Fgfr1 prevented formation of nephron progenitor cell aggregates after injury and during kidney development. Implantation of FGF soaked beads induced local aggregation of lhx1a:EGFP + kidney progenitor cells. Our results reveal a previously unexplored role for FGF signaling in recruitment of renal progenitors to sites of new nephron formation and suggest a role for FGF signaling in maintaining cell adhesion and cell polarity in newly forming kidney epithelia.
Kamei, Caramai N.; Gallegos, Thomas F.; Liu, Yan; Hukriede, Neil; Drummond, Iain A. Development. 146(8). April 2019.
Zebrafish kidneys use resident kidney stem cells to replace damaged tubules with new nephrons: the filtration units of the kidney. What stimulates kidney progenitor cells to form new nephrons is not known. Here, we show that wnt9a and wnt9b are induced in the injured kidney at sites where frizzled9b- and lef1-expressing progenitor cells form new nephrons. New nephron aggregates are patterned by Wnt signaling, with high canonical Wnt-signaling cells forming a single cell thick rosette that demarcates: domains of cell proliferation in the elongating nephron; and tubule fusion where the new nephron plumbs into the distal tubule and establishes blood filtrate drainage. Pharmacological blockade of canonical Wnt signaling inhibited new nephron formation after injury by inhibiting cell proliferation, and resulted in loss of polarized rosette structures in the aggregates. Mutation in frizzled9b reduced total kidney nephron number, caused defects in tubule morphology and reduced regeneration of new nephrons after injury. Our results demonstrate an essential role for Wnt/frizzled signaling in adult zebrafish kidney development and regeneration, highlighting conserved mechanisms underlying both mammalian kidney development and kidney stem cell-directed neonephrogenesis in zebrafish.
Oxburgh, L; Carroll, TJ; Cleaver, O; Gossett, DR; Hoshizaki, DK; Hubbell, JA; Humphreys, BD; Jain, S; Jensen, J; Kaplan, DL; Kesselman, C; Ketchum, CJ; Little, MH; McMahon, AP; Shankland, SJ; Spence, JR; Valerius, MT; Wertheim, JA; Wessely, O; Zheng, Y; Drummond, IA. J Am Soc Nephrol. 28(5):1370–1378. May 2017.
(Re)Building a Kidney is a National Institute of Diabetes and Digestive and Kidney Diseases-led consortium to optimize approaches for the isolation, expansion, and differentiation of appropriate kidney cell types and the integration of these cells into complex structures that replicate human kidney function. The ultimate goals of the consortium are two-fold: to develop and implement strategies for in vitro engineering of replacement kidney tissue, and to devise strategies to stimulate regeneration of nephrons in situ to restore failing kidney function. Projects within the consortium will answer fundamental questions regarding human gene expression in the developing kidney, essential signaling crosstalk between distinct cell types of the developing kidney, how to derive the many cell types of the kidney through directed differentiation of human pluripotent stem cells, which bioengineering or scaffolding strategies have the most potential for kidney tissue formation, and basic parameters of the regenerative response to injury. As these projects progress, the consortium will incorporate systematic investigations in physiologic function of in vitro and in vivo differentiated kidney tissue, strategies for engraftment in experimental animals, and development of therapeutic approaches to activate innate reparative responses.