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Updated: May 1, 2026
Quantitative PCR-based Assay to Measure Sonic Hedgehog Signaling in Cellular Model of Ciliogenesis
Published on: January 31, 2025
Downregulating hedgehog signaling reduces renal cystogenic potential of mouse models
Pamela V Tran1, George C Talbott2, Annick Turbe-Doan2
1Genetics Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Anatomy and Cell Biology and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas; and ptran@kumc.edu.
Abstract:
Renal cystic diseases are a leading cause of renal failure. Mutations associated with renal cystic diseases reside in genes encoding proteins that localize to primary cilia. These cystoproteins can disrupt ciliary structure or cilia-mediated signaling, although molecular mechanisms connecting cilia function to renal cystogenesis remain unclear. The ciliary gene, Thm1(Ttc21b), negatively regulates Hedgehog signaling and is most commonly mutated in ciliopathies. We report that loss of murine Thm1 causes cystic kidney disease, with persistent proliferation of renal cells, elevated cAMP levels, and enhanced expression of Hedgehog signaling genes. Notably, the cAMP-mediated cystogenic potential of Thm1-null kidney explants was reduced by genetically deleting Gli2, a major transcriptional activator of the Hedgehog pathway, or by culturing with small molecule Hedgehog inhibitors. These Hedgehog inhibitors acted independently of protein kinase A and Wnt inhibitors. Furthermore, simultaneous deletion of Gli2 attenuated the renal cystic disease associated with deletion of Thm1. Finally, transcripts of Hedgehog target genes increased in cystic kidneys of two other orthologous mouse mutants, jck and Pkd1, and Hedgehog inhibitors reduced cystogenesis in jck and Pkd1 cultured kidneys. Thus, enhanced Hedgehog activity may have a general role in renal cystogenesis and thereby present a novel therapeutic target.
Insights
Loss of the Thm1 gene causes cystic kidney disease by enhancing Hedgehog signaling. Inhibiting this pathway reduced cyst growth in mouse models, suggesting a new therapeutic target for renal cystic diseases.
Area of Science:
- Nephrology
- Genetics
- Cell Biology
Background:
- Renal cystic diseases are a major cause of kidney failure.
- Mutations in genes affecting primary cilia proteins are linked to these diseases.
- The ciliary gene Thm1 (Ttc21b) regulates Hedgehog signaling and is implicated in ciliopathies.
Purpose of the Study:
- To investigate the role of Thm1 in renal cystogenesis.
- To explore the connection between Thm1, Hedgehog signaling, and cAMP in kidney disease.
- To evaluate Hedgehog signaling as a potential therapeutic target for renal cystic diseases.
Main Methods:
- Generated and analyzed Thm1-null mouse models.
- Assessed renal cell proliferation, cAMP levels, and gene expression.
- Utilized genetic deletion of Gli2 and small molecule Hedgehog inhibitors.
- Examined cystogenesis in kidney explants from Thm1-null, jck, and Pkd1 mice.
Main Results:
- Loss of Thm1 in mice led to cystic kidney disease, characterized by cell proliferation, elevated cAMP, and increased Hedgehog signaling.
- Genetic deletion of Gli2 or Hedgehog inhibition reduced cystogenic potential in Thm1-null kidney explants.
- Simultaneous deletion of Gli2 attenuated renal cystic disease in Thm1-deficient mice.
- Hedgehog pathway activation was observed in other cystic kidney disease models (jck, Pkd1), and inhibitors reduced cystogenesis.
Conclusions:
- Enhanced Hedgehog signaling plays a significant role in Thm1-associated renal cystic disease.
- Hedgehog pathway inhibition is a potential therapeutic strategy for various forms of renal cystic disease.
- Targeting Hedgehog signaling may offer a novel approach to treating kidney cystogenesis.
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