Targeting the distal renal tubule by siRNA in the mouse
Wissenschaftliches Arbeitsprogramm
Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a progressive hereditary disorder that often leads to kidney failure in mid-adulthood. The underlying molecular mechanisms remain poorly understood, and no targeted therapies are currently available. One of the most common subtypes, ADTKD-MUC1, is caused by a specific germline frameshift mutation in MUC1, resulting in the toxic neoprotein MUC1-fs, which accumulates within the secretory pathway of distal tubular epithelial cells and contributes to tubular damage. Recent data from our lab has shown that allele-specific siRNA can effectively suppress MUC1-fs expression in patient-derived tubular cells, highlighting RNA interference as a promising therapeutic approach.
A major remaining challenge is the efficient delivery of siRNA to the distal nephron. While freely filtered siRNA is readily taken up by the proximal tubule, the distal tubule is largely inaccessible under physiological conditions. However, in murine models of chronic kidney injury, distal tubular uptake increases substantially, enabling knockdown efficiencies of up to 70%. Since murine Muc1 expression —analogous to human MUC1 — i s restricted to the distal nephron, establishing robust siRNA delivery to this segment is essential.
This project aims to systematically evaluate and optimize Muc1 knockdown in a murine system as a prerequisite for therapeutic development. Using the Muc1-expressing mouse epithelial cell line KPC-792, we will validate Muc1-directed antibodies and identify the most effective siRNA candidates at both mRNA and protein levels. We will also establish immunohistochemistry and in situ hybridization protocols to quantify in vivo knockdown. Finally, proof-of-concept studies will assess siRNA delivery in healthy and fibrotic mouse kidneys, including the use of micelle-based nanocarriers developed with the Institute of Nanotechnology, Los Angeles, to enhance targeting of the distal tubule.