Abstract: TH-PO797
Biallelic ANKS6 and NPHP1 Mutations Alter Ciliary LKB1 Assembly in Late-Onset Ciliopathies
Session Information
- Genetic Diseases of the Kidney - I
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1002 Genetic Diseases of the Kidneys: Non-Cystic
Authors
- Schwarz, Hannah, University Hospital Erlangen, Erlangen, Germany
- Schueler, Markus, University Hospital Erlangen, Erlangen, Germany
- Torabi sarijalo, Nasrin, University Hospital Erlangen, Erlangen, Germany
- Jobst-Schwan, Tilman, University Hospital Erlangen, Erlangen, Germany
- Schiffer, Mario, University Hospital Erlangen, Erlangen, Germany
- Knaup, Karl Xaver, University Hospital Erlangen, Erlangen, Germany
- Wiesener, Michael Sean, University Hospital Erlangen, Erlangen, Germany
Background
Nephronophthisis is a frequent cause of renal failure in children, presenting with progressive renal fibrosis and commonly include extrarenal organ involvement. The use of technological advances in DNA sequencing has led to a better understanding of molecular causes in rare kidney diseases. However, for most of these the cellular pathways involved still need to be identified. ANKS6 is a known member of the Inversin compartment and interacts with ANKS3. The Liver kinase B1 (LKB1) was recently shown to form a regulatory module in primary cilia with proteins linked to NPHP.
Methods
Genetic testing was performed in affected individuals with CKD of unknown origin. DNA was extracted from whole blood, enriched, and sequenced on a HiSeq2500. Patient-derived fibroblasts were harvested and cultured from skin biopsies of affected individuals, healthy parent and controls. From these patient derived cells functional studies on protein and RNA level using immunoblotting, immunofluorescence and qRT-PCR were performed.
Results
We identified biallelic mutations in the genes NPHP1 and ANKS6 in affected individuals with CKD of unknown origin. These segregated with the affected status and were absent from healthy controls. Functional studies in patient derived fibroblasts demonstrate that the identified mutations alter the ciliary assembly of LKB1 as well as of downstream signaling pathways, compared to healthy controls and heterozygous parental cells. Moreover, the detected mutations in ANKS6 disrupt the Inversin-complex as the mutations lead to a loss of ANKS6, NPHP3, Inversin and NEK8 in primary cilia.
Conclusion
We identified the underlying molecular cause in affected individuals with CKD of unknown origin and observed an alteration of the ciliary assembly of LKB1 as well as of downstream signaling in patient derived cells. These findings support the presence of a ciliary LKB1-NPHP functional interaction. Moreover the results indicate that an alteration of ciliary LKB1 signaling could be a relevant mechanism for human ciliopathy and may play a wider role in renal disease. Functional studies on patient derived cells with rare inherited kidney diseases may lead to a better understanding of disease mechanisms. This could help to develop novel therapeutic strategies for treatment of such rare disorders.