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The PI3K pathway balances self-renewal and differentiation of nephron progenitor cells through β-catenin signaling.

Lindström NO, Carragher NO, Hohenstein P - Stem Cell Reports (2015)

Bottom Line: Nephron progenitor cells differentiate to form nephrons during embryonic kidney development.In contrast, self-renewal maintains progenitor numbers and premature depletion leads to impaired kidney function.Here we analyze the PI3K pathway as a point of convergence for the multiple pathways that are known to control self-renewal in the kidney.

View Article: PubMed Central - PubMed

Affiliation: The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK; Edinburgh Cancer Research Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XR, UK. Electronic address: nils.lindstrom@roslin.ed.ac.uk.

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PI3K Inhibition Results in Ectopic Activation of β-cateninTcf/Lef Signaling in Nephron Progenitor Cells(A) Time-lapse data showing E12.5 TCF/Lef::H2B-GFP kidneys cultured for 49 hr. (Right) Fixed and stained kidneys. Blue dashed line surrounds the nephron progenitor cells; white arrowheads indicate points of ectopic sites of GFP expression; white dashed line outlines ureteric bud epithelium and indicates ectopic GFP expression also positive for Cdh1.(B) E12.5 kidneys cultured for 48 hr.(C) Isolated mesenchyme cultured without the ureteric bud.(D) Regions of ENPs and UBTs from whole kidneys cultured for 24 hr. Arrowheads indicate sites of ectopic expression. Cm, cap mesenchyme; ub, ureteric bud. Culture conditions and labeling are as indicated in figures. See also Figures S3 and S4.
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fig3: PI3K Inhibition Results in Ectopic Activation of β-cateninTcf/Lef Signaling in Nephron Progenitor Cells(A) Time-lapse data showing E12.5 TCF/Lef::H2B-GFP kidneys cultured for 49 hr. (Right) Fixed and stained kidneys. Blue dashed line surrounds the nephron progenitor cells; white arrowheads indicate points of ectopic sites of GFP expression; white dashed line outlines ureteric bud epithelium and indicates ectopic GFP expression also positive for Cdh1.(B) E12.5 kidneys cultured for 48 hr.(C) Isolated mesenchyme cultured without the ureteric bud.(D) Regions of ENPs and UBTs from whole kidneys cultured for 24 hr. Arrowheads indicate sites of ectopic expression. Cm, cap mesenchyme; ub, ureteric bud. Culture conditions and labeling are as indicated in figures. See also Figures S3 and S4.

Mentions: The differentiation of ENPs is positively controlled by β-catenin activity in the ENPs in response to a WNT9B signal from the ureteric bud (Karner et al., 2011; Park et al., 2012). We used time-lapse analysis of the TCF/Lef::H2B-GFP β-catenin activity reporter mouse (Ferrer-Vaquer et al., 2010) to test the involvement of β-catenin in the ectopic nephrons obtained through PI3K inhibition. In control cultures, low-level activity of the reporter could be seen in the ENPs in the cap mesenchyme, and the signal increased in epithelialized CDH1+ nephrons (Figure 3A, top; Movie S2; Figures S3A and S3B). Ly294002 treatment of reporter kidneys resulted in activity of the β-catenin-signaling pathway in the ectopic nephrons, and these GFP+ structures later became CDH1+ (Figure 3A, bottom; Movie S2). To test if β-catenin activity is required for PI3K inhibition-induced nephron induction, we used IWR1, a Tankyrase inhibitor that results in inhibition of β-catenin signaling. We confirmed that IWR1 specifically reduced β-catenin targets and the β-catenin-signaling reporter in kidneys, and IWR1 effectively blocked Ly294002-induced ectopic nephrons (Figure 3B; Figures S3C–S3E).


The PI3K pathway balances self-renewal and differentiation of nephron progenitor cells through β-catenin signaling.

Lindström NO, Carragher NO, Hohenstein P - Stem Cell Reports (2015)

PI3K Inhibition Results in Ectopic Activation of β-cateninTcf/Lef Signaling in Nephron Progenitor Cells(A) Time-lapse data showing E12.5 TCF/Lef::H2B-GFP kidneys cultured for 49 hr. (Right) Fixed and stained kidneys. Blue dashed line surrounds the nephron progenitor cells; white arrowheads indicate points of ectopic sites of GFP expression; white dashed line outlines ureteric bud epithelium and indicates ectopic GFP expression also positive for Cdh1.(B) E12.5 kidneys cultured for 48 hr.(C) Isolated mesenchyme cultured without the ureteric bud.(D) Regions of ENPs and UBTs from whole kidneys cultured for 24 hr. Arrowheads indicate sites of ectopic expression. Cm, cap mesenchyme; ub, ureteric bud. Culture conditions and labeling are as indicated in figures. See also Figures S3 and S4.
© Copyright Policy - CC BY
Related In: Results  -  Collection

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fig3: PI3K Inhibition Results in Ectopic Activation of β-cateninTcf/Lef Signaling in Nephron Progenitor Cells(A) Time-lapse data showing E12.5 TCF/Lef::H2B-GFP kidneys cultured for 49 hr. (Right) Fixed and stained kidneys. Blue dashed line surrounds the nephron progenitor cells; white arrowheads indicate points of ectopic sites of GFP expression; white dashed line outlines ureteric bud epithelium and indicates ectopic GFP expression also positive for Cdh1.(B) E12.5 kidneys cultured for 48 hr.(C) Isolated mesenchyme cultured without the ureteric bud.(D) Regions of ENPs and UBTs from whole kidneys cultured for 24 hr. Arrowheads indicate sites of ectopic expression. Cm, cap mesenchyme; ub, ureteric bud. Culture conditions and labeling are as indicated in figures. See also Figures S3 and S4.
Mentions: The differentiation of ENPs is positively controlled by β-catenin activity in the ENPs in response to a WNT9B signal from the ureteric bud (Karner et al., 2011; Park et al., 2012). We used time-lapse analysis of the TCF/Lef::H2B-GFP β-catenin activity reporter mouse (Ferrer-Vaquer et al., 2010) to test the involvement of β-catenin in the ectopic nephrons obtained through PI3K inhibition. In control cultures, low-level activity of the reporter could be seen in the ENPs in the cap mesenchyme, and the signal increased in epithelialized CDH1+ nephrons (Figure 3A, top; Movie S2; Figures S3A and S3B). Ly294002 treatment of reporter kidneys resulted in activity of the β-catenin-signaling pathway in the ectopic nephrons, and these GFP+ structures later became CDH1+ (Figure 3A, bottom; Movie S2). To test if β-catenin activity is required for PI3K inhibition-induced nephron induction, we used IWR1, a Tankyrase inhibitor that results in inhibition of β-catenin signaling. We confirmed that IWR1 specifically reduced β-catenin targets and the β-catenin-signaling reporter in kidneys, and IWR1 effectively blocked Ly294002-induced ectopic nephrons (Figure 3B; Figures S3C–S3E).

Bottom Line: Nephron progenitor cells differentiate to form nephrons during embryonic kidney development.In contrast, self-renewal maintains progenitor numbers and premature depletion leads to impaired kidney function.Here we analyze the PI3K pathway as a point of convergence for the multiple pathways that are known to control self-renewal in the kidney.

View Article: PubMed Central - PubMed

Affiliation: The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK; Edinburgh Cancer Research Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XR, UK. Electronic address: nils.lindstrom@roslin.ed.ac.uk.

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Related in: MedlinePlus