Abstract 300: The Notch Signaling Pathway Regulates the Fate of Renal FOXD1+ Stromal Cells and Their Descendants
The mechanisms underlying the establishment, assembly and maintenance of the renal blood vessels are poorly understood. We have previously shown that renal stromal cells, characterized by their early and transient expression of the transcription factor Forkhead box D1 (FOXD1), are precursors for several cell populations of the renal vasculature, including arterial smooth muscle cells (SMCs), renin cells, pericytes, and mesangial cells. To better understand the role and fate of FOXD1+ stromal cells, we isolated FOXD1+ cells and their descendents. Mice with cre recombinase knocked into the FOXD1 locus (FOXD1-cre) were crossed with mice carrying the mT/mG reporter, which exchanges RFP expression for GFP upon cre-mediated recombination. GFP-positive FOXD1-lineage cells were isolated from the kidney using FACS. These cells comprised on average 19% (n=8) of adult kidney cells. As expected, these cells expressed markers of SMCs (α-smooth muscle actin) and renin cells (renin), as shown by RT-PCR. Interestingly, the cells did not express markers of endothelial cells, including Tie2 and β-globin. Prior data from our lab also demonstrated that the transcription factor “Recombination signal binding protein for immunoglobulin kappa J region” (RBP-J), the final transcriptional mediator of Notch signaling, is expressed in FOXD1-lineage cells and plays a key role in their differentiation, as deletion of RBP-J using FOXD1-cre led to severe reductions of the endowment of FOXD1+ descendants, with subsequent renal abnormalities including glomerular aneurysms, and vessel fibrosis. To better understand this phenotype, we wished to identify the Notch-pathway receptors and ligands expressed in FOXD1-lineage cells. RT-PCR analysis showed the expression of Notch 3 and Jagged 2 in both adult and newborn (postnatal day 1) animals, and Notch 2 and Jagged 1 exclusively at the newborn stage. Deletion of Notch 1 or 2 within FOXD1 cells failed to reproduce the phenotype of RBP-J deletion. However, mutant animals exhibited glomerulosclerosis and regions of fibrosis. In addition, a small number of arteries appear to enter the renal parenchyma from the subcapsular region, an inversion of the normal pattern, indicating a possible role for the Notch receptor in renal vessel guidance.
Author Disclosures: E.E. Lin: None. E.S. Pentz: None. M. Li: None. M.S. Sequeira-Lopez: None. R.A. Gomez: None.
This research has received full or partial funding support from the American Heart Association, Mid-Atlantic Affiliate (Maryland, North Carolina, South Carolina, Virginia & Washington, DC).
- © 2014 by American Heart Association, Inc.