Kolvenbach, C. M. | Search bioRxiv

bioRxiv2025

A kidney specific mouse model to study the effects of in vivo induction of Yamanaka factors

IntroductionMaladaptive repair after acute kidney injury (AKI) leads to fibrosis and chronic kidney disease (CKD). Improving the resilience and stimulating tissue repair after injury is crucial to prevent AKI-to-CKD transition. Using a combination of transcription factors (Yamanaka factors Oct4, Klf4 and Sox2, "OKS") to partially reprogram tissues and enhance regeneration in vivo, could be a promising approach as shown by amelioration after various organ injury, yet not investigated for AKI to date. MethodsWe used a ubiquitously and kidney-specific transgenic mouse model to investigate OKS expression in kidney. In a kidney-specific model using Pax8-Cre, we then induced AKI via aristolochic acid (AA), simultaneously expressing OKS to determine potential protective effects after kidney injury. ResultsWe show that a ubiquitously expressing OKS-mouse model was not suitable due to toxic effects and limited kidney expression. In the Pax8-Cre mouse model, we observed expression almost exclusively to proximal tubules. While induction for more than 3 days caused dysplastic tumor formation, an induction regimen limited to 3 days was not able to improve phenotypic outcome after AA-injury. ConclusionPartial reprogramming of the kidney using OKS is feasible; however, it requires a delicate balance to the risk of oncogenic transformation. Determine a dose that effectively promotes repair without crossing the threshold into harmful effects remains a major challenge, posing significant safety concerns for translating the approach to humans in the near future.

developmental biology↗

bioRxiv2025

CAKUT variants in PRPF8, DYRK2, and CEP78: implications for splicing and ciliogenesis

IntroductionCongenital anomalies of the kidney and urinary tract (CAKUT) are the leading cause of chronic kidney disease in children and young adults. Although over 50 monogenic causes have been identified, many remain unresolved. PRPF8 is a core spliceosome component, essential for pre-mRNA splicing, and further localizes to the distal mother centriole to promote ciliogenesis. MethodsWe performed trio exome sequencing in 208 CAKUT families and identified strong variants in PRPF8 and the EDD-DYRK2-DDB1VprBP complex. Functional validation included splicing assays in yeast (Saccharomyces cerevisiae), Sonic hedgehog (Shh) signaling in RPE-1 cells, co-immunoprecipitation for protein complex assembly, and in situ hybridization in mouse embryos. Protein interactions were modeled using AlphaFold. ResultsWe identified heterozygous de novo or inherited variants in PRPF8, DYRK2, DDB1, EDD and CEP78. Yeast assays revealed that while most PRPF8 variants preserved growth and splicing at consensus splice sites, the de novo PRPF8R1681W variant impaired splicing of non-consensus splice sites and was inviable at elevated temperature. CAKUT variants failed to rescue prp28-1 and U4-cs1 alleles but showed variant-specific synthetic interactions with brr2-1, including weak suppression or synthetic sickness at elevated temperatures. Shh signaling was reduced in [~]50% of PRPF8 variants expressed in RPE-1 cells. CEP78 truncating variants abrogated binding to CEP350 and VPRBP. Two DYRK2 variants disrupted EDD-DYRK2-DDB1VprBP complex formation without affecting kinase activity. In situ hybridization revealed strong Prpf8 expression in the developing collecting duct and urothelium. ConclusionVariants in PRPF8 and components of the EDD-DYRK2-DDB1VprBP complex may contribute to CAKUT through impaired pre-mRNA splicing and defective ciliogenesis. These findings uncover an entirely new functional network of candidate genes for CAKUT and ciliopathies, significantly broadening our understanding of disease mechanisms and offering novel entry points for mechanistic studies. Translational StatementOur study identifies a previously unrecognized molecular network involving PRPF8 and the EDD-DYRK2-DDB1VprBP complex, revealing a novel pathogenic mechanism in CAKUT. These results introduce a new class of candidate genes and pathways essential for kidney development. As the genetic etiology of CAKUT remains unknown in most patients, our findings underscore the need for targeted genetic testing and functional studies to enhance diagnosis, advance mechanistic insight, and enable more personalized clinical management.

genetics↗