Targeting GLP-1 signaling ameliorates cystogenesis in a zebrafish model of nephronophthisis

Nephronophthisis (NPH) is the leading genetic cause of end-stage renal disease in children and young adults, with no effective disease-modifying therapies currently available. Here, we identify glucagon-like peptide-1 (GLP-1) signaling as a novel therapeutic target for NPH through a systematic drug repurposing screen in zebrafish. By simultaneously depleting nphp1 and nphp4, we developed a robust zebrafish model that recapitulates key features of human NPH, including glomerular cyst formation. Our screen revealed that dipeptidyl peptidase-4 (DPP4) inhibitors (Omarigliptin and Linagliptin) and GLP-1 receptor agonists (Semaglutide) significantly reduce cystogenesis in a dose-dependent manner. Genetic analysis demonstrated that GLP-1 receptor signaling is important for maintaining pronephros integrity, with gcgra and gcgrb (GLP-1 receptor genes) playing a particularly important role. Transcriptomic profiling identified adenosine receptor A2ab (adora2ab) as a key downstream effector of GLP-1 signaling, which regulates ciliary morphology and prevents cyst formation. Notably, nphp1/nphp4 double mutant zebrafish exhibited upregulation of gcgra as a compensatory mechanism, explaining their resistance to cystogenesis. This compensation was disrupted by targeted depletion of GLP-1 receptors or inhibition of adenylate cyclase, resulting in enhanced cyst formation specifically in the mutant background. Our findings establish a signaling cascade from GLP-1 receptors to adora2ab in regulating ciliary organization and preventing cystogenesis, offering new therapeutic opportunities for NPH through repurposing of FDA-approved medications with established safety profiles. We performed RNA sequencing analysis comparing nphp1/nphp4 morphant embryos treated with Omarigliptin versus DMSO controls. At 24 hours post fertilization (hpf), embryos were incubated with Omarigliptin (25 µM) or DMSO. At 48 hpf, total RNA was extracted from 15-50 embryos per replicate.