Pkd1RC/RC mice demonstrate remodeling of purinergic receptors in ADPKD cysts

Polycystic kidney diseases (PKD) are characterized by development of multiple cysts, dilations of nephron segments, which replace normal tissues and lead to kidney insuffciency. To identify new gene pathways affected by cyst development in collecting ducts, we used a bulk RNAseq approach comparing gene expression of normal microdissected cortical collecting ducts (n=3 mice) vs cysts microdissected from Pkd1 RC/RC mice (n=4). Bulk-RNA analysis identified 18,000 genes and allowed statistical comparison of over 15,000 genes. Our data reveals that although cysts originate from normal collecting ducts, cystic epithelium show 2692 down-regulated and 2278 up-regulated genes (p<0.05 pAdj. FDR). Ingenuity Pathways Analysis identifies the following intracellular mechanisms mostly affected by transition: Rac and Rho signaling, fibrosis signaling, epithelial-to-mesenchymal transition, cytoskeleton rearrangement and ERK/MAPK signaling. Several of the differentially expressed genes were identified in GWAS of PKD, chronic kidney diseases and hypertension. Our previous publication reported that development of cysts in an autosomal recessive model of PKD is associated with a shift of P2Y to P2X receptor abundance. In the current study we found that in the autosomal dominant Pkd1 RC/RC mice purinergic signaling undergoes similar remodeling. The most abundant ionotropic receptors with reduced expression were P2ry2 -2.25; P2ry4 -1.37, log2 fold change, whereas ionotropic receptors P2rx5 and P2rx7 increased expression (2.88 and 1.53, log2 fold change, respectively). Additionally, analysis detected elevated abundance of P2ry6 and P2ry12 RNA level. We used a model of cystogenesis to test how P2X signaling affects growth of cysts formed by mpkCCD cl4 cells in Matrigel. Stimulation of P2X receptors with α,βMe-ATP significantly increases cyst growth. We hypothesize that the physiological significance of the predominant P2X signaling in the cysts include their role in regulation of ATP release via pannexin-1 channels. Abnormal ATP accumulation in the cyst space was shown earlier to contribute in cystogenesis and we previously showed that pannexin-1 mediates ATP release to the cyst lumen. Co-immunoprecipitatation experiments in mpkCCD cl4 cells revealed that P2X5 and P2X7 receptors bind pannexin-1 whereas P2Y6 and P2Y12 do not interact with pannexin-1. Interestingly, stimulation of cystogenesis with α,βMe-ATP was accompanied by increased abundance of pannexin-1. Lack of functional P2X5 in humans prioritizes P2X7 receptors as a therapeutic target in ADPKD. We conclude that development of ADPKD cysts involves massive transcriptome remodeling of collecting ducts which include a shift in purinergic signaling that facilitates pathogenic pannexin-1 hyperactivity. DK123266 and DK131114. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.