Abstract: FR-PO623
NOTCH2 Mutations Associated with Alagille Syndrome Result in Longer Primary Cilia and Inactivation of Ift88 in Mice with Notch Signaling-Deficient Kidneys Partly Rescues Kidney Abnormalities
Session Information
- Cystic Kidney Diseases: Mechanisms and Models
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1201 Genetic Diseases of the Kidneys: Cystic
Authors
- Mckillop, Matthew, Sanford Research, Sioux Falls, South Dakota, United States
- DeRiso, Jennifer, Sanford Research, Sioux Falls, South Dakota, United States
- Anwer, Ayesha, Sanford Research, Sioux Falls, South Dakota, United States
- Surendran, Kameswaran, Sanford Research, Sioux Falls, South Dakota, United States
Group or Team Name
- Surendran Lab.
Background
Alagille Syndrome (ALGS) is an autosomal dominant congenital disorder linked to mutations in NOTCH2, which codes for a receptor in the Notch signaling pathway. ALGS has a variable penetrance of kidney disease with a variety of kidney abnormalities including hypoplastic and multi-cystic kidneys. Notch signaling deficiency in nascent nephrons in mice results in small multi-cystic kidneys and epithelial cells with long primary cilia. It is unknown if NOTCH2 mutations associated with kidney disease in ALGS also result in longer cilia. Also unknown is if the long cilia mediate cyst formation in the kidney and decline in renal function in mice with Notch-signaling deficient kidneys.
Methods
We analyzed kidney structure and function in mice with inactivation of one allele of Notch1 and two alleles of Notch2 along with varying number of Intraflagellar transport protein 88 (Ift88) alleles in developing mouse nephrons . We modeled ALGS associated NOTCH2 R2003X (N2R2003X) and NOTCH2 Exon33 splice acceptor (N2Ex33sp) mutations in Madin-Darby Canine Kidney (MDCK) and performed RNA-sequencing to identify differentially expressed genes. We also determined proteins that are proximal to Notch2 versus N2Ex33sp mutant in MDCK cells.
Results
Cystic kidney phenotype and decline in renal function in mice with Notch1 & 2 deficient kidneys were rescued when Ift88 is in the heterozygous state. MDCK cells with N2R2003X and N2Ex33sp mutations have longer cilia while inactivating both alleles of Notch2 by introducing a stop codon into exon5 in MDCK (N2-/-) does not increase cilia length. Many primary cilia related genes are differentially expressed in N2Ex33sp and not in N2-/- cells compared with wild type cells. Many cilium assembly proteins are proximal to wild type Notch2 and not N2Ex33sp mutant.
Conclusion
ALGS associated N2+/R2003X and N2+/Ex33sp mutations, which result in truncated Notch2 proteins, likely function in a dominant manner and the long cilia phenotype is not just due to loss of Notch2. While many cilia related genes are differentially expressed in N2+/Ex33sp cells, and N2Ex33sp mutant protein has reduced proximity to cilium assembly proteins, partial inactivation of Ift88 suppresses Notch-deficiency dependent kidney disease.
Funding
- NIDDK Support