Search

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most prevalent genetic disorder affecting the kidneys. Understanding epigenetic regulatory mechanisms and the role of microRNAs (miRNAs) is crucial for developing therapeutic interventions. Two mRNA datasets (GSE7869 and GSE35831) and miRNA expression data (GSE133530) from ADPKD patients were used to find differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs), with a focus on genes regulated by hub transcription factors (TFs) and their target genes. The expression of hub TFs was validated in human kidneys and animal models through Western Blot (WB) and RT-PCR analysis. The location of the hub TF proteins in kidney cells was observed by a laser confocal microscope. A total of 2037 DEGs were identified. DEM analysis resulted in 59 up-regulated and 107 down-regulated miRNAs. Predicted target DEGs of DEMs indicated two top dysregulated TFs: hepatocyte nuclear factor 4 alpha (HNF4α) and Kruppel-like factor 4 (KLF4). RT-PCR, WB, and immunochemistry results showed that mRNA and protein levels of HNF4α were significantly decreased while KLF4 levels were significantly up-regulated in human ADPKD kidneys and Pkd1 conditional knockout mice compared with normal controls. Laser confocal microscopy revealed that KLF4 was mainly located in the cytoplasm while HNF4α was in the nucleus. Functional enrichment analysis indicated that genes regulated by HNF4α were mainly associated with metabolic pathways, while KLF4-regulated genes were linked to kidney development. Drug response prediction analysis revealed potential drug candidates for ADPKD treatment, including BI-2536, Sepantronium, and AZD5582. This integrated analysis provides new epigenetic insights into the complex miRNA-TF-mRNA network in ADPKD and identifies HNF4α and KLF4 as key TFs. These findings offer valuable resources for further research and potential drug development for ADPKD., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Cheng Xue reports was provided by Shanghai Changzheng Hospital. Cheng Xue reports a relationship with Shanghai Changzheng Hospital that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In autosomal dominant polycystic kidney disease (ADPKD) there is cyst growth in the kidneys that leads to chronic kidney disease often requiring dialysis or kidney transplantation. There is enhanced aerobic glycolysis (Warburg effect) in the cyst lining epithelial cells that contributes to cyst growth. The glucose mimetic, 2-Deoxy-d-glucose (2-DG) inhibits glycolysis. The effect of early and late administration of 2-DG on cyst growth and kidney function was determined in Pkd1 RC/RC mice, a hypomorphic PKD model orthologous to human disease. Early administration of 2-DG resulted in decreased kidney weight, cyst index, cyst number and cyst size, but no change in kidney function. 2-DG decreased proliferation. a major mediator of cyst growth, of cells lining the cyst. Late administration of 2-DG did not have an effect on cyst growth or kidney function. To determine mechanisms of decreased proliferation, an array of mTOR and autophagy proteins was measured in the kidney. 2-DG suppressed autophagic flux in Pkd1 RC/RC kidneys and decreased autophagy proteins, ATG3, ATG5 and ATG12-5. 2-DG had no effect on p-mTOR or p-S6 (mTORC1) and decreased p-AMPK. 2-DG decreased p-4E-BP1, p-c-Myc and p-ERK that are known to promote proliferation and cyst growth in PKD. 2-DG decreased p-AKT S473 , a marker of mTORC2. So the role of mTORC2 in cyst growth was determined. Knockout of Rictor (mTORC2) in Pkd1 knockout mice did not change the PKD phenotype. In summary, 2-DG decreases proliferation in cells lining the cyst and decreases cyst growth by decreasing proteins that are known to promote proliferation. In conclusion, the present study reinforces the therapeutic potential of 2-DG for use in patients with ADPKD., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Charles Edelstein reports financial support was provided by US Department of Defense. Charles Edelstein reports financial support was provided by US Department of Veterans Affairs. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Background: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a prevalent genetic disorder characterized by the formation of renal cysts leading to kidney failure. Despite known genetic underpinnings, the variability in disease progression suggests additional regulatory layers, including epigenetic modifications., Methods: We utilized various ADPKD models, including Pkd1 and Ezh2 conditional knockout (Pkd1 delta/delta :Ezh2 delta/delta ) mice, to explore the role of Enhancer of Zeste Homolog 2 (EZH2) in cystogenesis. Pharmacological inhibition of EZH2 was performed using GSK126 or EPZ-6438 across multiple models., Results: EZH2 expression was significantly upregulated in Pkd1 -/- cells, Pkd1 delta/delta mice, and human ADPKD kidneys. EZH2 inhibition attenuates cyst development in MDCK cells and a mouse embryonic kidney cyst model. Both Ezh2 conditional knockout and GSK126 treatment suppressed renal cyst growth and protected renal function in Pkd1 delta/delta mice. Mechanistically, cAMP/PKA/CREB pathway increased EZH2 expression. EZH2 mediated cystogenesis by enhancing methylation and activation of STAT3, promoting cell cycle through p21 suppression, and stimulating non-phosphorylated β-catenin in Wnt signaling pathway. Additionally, EZH2 enhanced ferroptosis by inhibiting SLC7A11 and GPX4 in ADPKD., Conclusion: Our findings elucidate the pivotal role of EZH2 in promoting renal cyst growth through epigenetic mechanisms and suggest that EZH2 inhibition or ablation may serve as a novel therapeutic approach for managing ADPKD., (© 2024. The Author(s).)

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and causes significant morbidity, ultimately leading to kidney failure. PKD pathogenesis is characterized by complex and dynamic alterations in multiple cell types during disease progression, hampering a deeper understanding of disease mechanism and the development of therapeutic approaches. Here, we generate a single-nucleus multimodal atlas of an orthologous mouse PKD model at early, mid, and late timepoints, consisting of 125,434 single-nucleus transcriptomic and epigenetic multiomes. We catalog differentially expressed genes and activated epigenetic regions in each cell type during PKD progression, characterizing cell-type-specific responses to Pkd1 deletion. We describe heterogeneous, atypical collecting duct cells as well as proximal tubular cells that constitute cyst epithelia in PKD. The transcriptional regulation of the cyst lining cell marker GPRC5A is conserved between mouse and human PKD cystic epithelia, suggesting shared gene regulatory pathways. Our single-nucleus multiomic analysis of mouse PKD provides a foundation to understand the earliest changes molecular deregulation in a mouse model of PKD at a single-cell resolution., Competing Interests: Competing interests statement:B.D.H. is a consultant for Janssen Research & Development, LLC, Pfizer and Chinook Therapeutics. B.D.H holds equity in Chinook Therapeutics. B.D.H holds grant funding from Chinook Therapeutics and Janssen Research & Development, LLC. O.M.W has received grants from AstraZeneca unrelated to the current work.

Polycystin-1 (PC1) is the protein product of the PKD1 gene whose mutation causes autosomal dominant Polycystic Kidney Disease (ADPKD). PC1 is an atypical G protein-coupled receptor (GPCR) with an autocatalytic GAIN domain that cleaves PC1 into extracellular N-terminal and membrane-embedded C-terminal (CTF) fragments. Recently, activation of PC1 CTF signaling was shown to be regulated by a stalk tethered agonist (TA), resembling the mechanism observed for adhesion GPCRs. Here, synthetic peptides of the first 9- (p9), 17- (p17), and 21-residues (p21) of the PC1 stalk TA were shown to re-activate signaling by a stalkless CTF mutant in human cell culture assays. Novel Peptide Gaussian accelerated molecular dynamics (Pep-GaMD) simulations elucidated binding conformations of p9, p17, and p21 and revealed multiple specific binding regions to the stalkless CTF. Peptide agonists binding to the TOP domain of PC1 induced close TOP-putative pore loop interactions, a characteristic feature of stalk TA-mediated PC1 CTF activation. Additional sequence coevolution analyses showed the peptide binding regions were consistent with covarying residue pairs identified between the TOP domain and the stalk TA. These insights into the structural dynamic mechanism of PC1 activation by TA peptide agonists provide an in-depth understanding that will facilitate the development of therapeutics targeting PC1 for ADPKD treatment., Competing Interests: SP, BM, KJ, EN, AH, RM, YM No competing interests declared, (© 2024, Pawnikar et al.)

Autosomal dominant polycystic kidney disease (ADPKD) is a predominant genetic disease, which is caused by mutations in PKD genes and is associated with DNA damage in cystic cells. The intrinsic stimulator of interferon genes (STING) pathway is crucial for recognizing damaged DNA in the cytosol, triggering the expression of inflammatory cytokines to activate defense mechanisms. However, the precise roles and mechanisms of STING in ADPKD remain elusive. In this study, we show that Pkd1 mutant mouse kidneys show upregulation of STING, which is stimulated by the DNAs of nuclear and mitochondrial origin. The activation of STING promotes cyst growth through increasing (1) the activation of NF-κB in Pkd1 mutant cells and (2) the recruitment of macrophages in the interstitial and peri-cystic regions in Pkd1 mutant mouse kidneys via NF-κB mediating the upregulation of TNF-α and MCP-1. Targeting STING with its specific inhibitor C-176 delays cyst growth in an early-stage aggressive Pkd1 conditional knockout mouse model and a milder long-lasting Pkd1 mutant mouse model. Targeting STING normalizes mitochondrial structure and function, decreases the formation of micronuclei, induces Pkd1 mutant renal epithelial cell death via p53 signaling, and decreases renal fibrosis in Pkd1 mutant mouse kidneys. These results support that STING is a novel therapeutic target for ADPKD treatment.

Rationale & Objective: In this pilot study, we hypothesized that autosomal dominant polycystic kidney disease (ADPKD) is characterized by impaired kidney oxidative metabolism that associates with kidney size and cyst burden., Study Design: Cross-sectional study., Setting & Participants: Twenty adults with ADPKD (age, 31±6 years; 65% women; body mass index [BMI], 26.8 [22.7-30.4] kg/m 2 ; estimated glomerular filtration rate [eGFR, 2021 CKD-EPI creatinine], 103±18mL/min/1.73m 2 ; height-adjusted total kidney volume [HTKV], 731±370mL/m; Mayo classifications 1B [5%], 1C [42%], 1D [21%], and 1E [32%]) and 11 controls in normal weight category (NWC) (age, 25±3 years; 45% women; BMI, 22.5 [21.7-24.2] kg/m2; eGFR, 113±15mL/min/1.73m 2 ; HTKV, 159±31mL/m) at the University of Colorado Anschutz Medical Campus., Predictors: ADPKD status (yes/no) and severity (Mayo classifications)., Outcome: HTKV and cyst burden by magnetic resonance imaging, kidney oxidative metabolism, and perfusion by 11 C-acetate positron emission tomography/computed tomography, insulin sensitivity by hyperinsulinemic-euglycemic clamps (presented as ratio of M-value of steady state insulin concentration [M/I])., Analytical Approach: For categorical variables, χ 2 /Fisher's exact tests, and for continuous variables t tests/Mann-Whitney U tests. Pearson correlation was used to estimate the relationships between variables., Results: Compared with NWC individuals, the participants with ADPKD exhibited lower mean±SD M/I ratio (0.586±0.205 vs 0.424±0.171 [mg/kg lean/min]/(μIU/mL), P=0.04), lower median cortical perfusion (1.93 [IQR, 1.80-2.09] vs 0.68 [IQR, 0.47-1.04] mL/min/g, P<0.001) and lower median total kidney oxidative metabolism (0.17 [IQR, 0.16-0.19] vs. 0.14 [IQR, 0.12-0.15] min -1 , P=0.001) in voxel-wise models excluding cysts. HTKV correlated inversely with cortical perfusion (r: -0.83, P < 0.001), total kidney oxidative metabolism (r: -0.61, P<0.001) and M/I (r: -0.41, P = 0.03)., Limitations: Small sample size and cross-sectional design., Conclusions: Adults with ADPKD and preserved kidney function exhibited impaired renal perfusion and kidney oxidative metabolism across a wide range of cysts and kidney enlargements., Funding: Grants from government (National Institutes of Health, Centers for Disease Control and Prevention) and not-for-profit (JDRF) entities., Trial Registration: Registered at ClinicalTrials.gov with study numbers NCT04407481 and NCT04074668., Plain-Language Summary: In our study, we explored how a common genetic kidney condition, autosomal dominant polycystic kidney disease (ADPKD), relates to kidney metabolism. ADPKD leads to the growth of numerous cysts in the kidneys, which can impact their ability to work properly. We wanted to understand the kidneys' ability to process oxygen and blood flow in ADPKD. Our approach involved using advanced imaging techniques to observe kidney metabolism and blood flow in people with ADPKD compared with healthy individuals. We discovered that those with ADPKD had significant changes in kidney oxygen metabolism even when their kidney function was still normal. These findings are crucial as they provide deeper insights into ADPKD, potentially guiding future treatments to target these changes., (Copyright © 2024 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: Autosomal dominant polycystic kidney disease (ADPKD) is the most common cause of end-stage kidney disease. It has been shown that Acyl-CoA thioesterase 13 ( ACOT13 ) level was reduced in renal cystic tissues from ADPKD patients. However, the role of ACOT13 in ADPKD remains largely elusive., Methods: The data in the GSE7869 dataset were acquired from the GEO database to determine ACOT13 level between normal renal cortical tissues and renal cystic tissues. Next, the potential functions of ACOT13 were explored by gene set enrichment analysis (GSEA). Furthermore, ACOT13 level in ADPKD cells (WT9-12) was verified by RT-qPCR. The effects of ACOT13 on WT9-12 cell growth were evaluated using the EdU staining and flow cytometry assays., Results: Compared to normal group, ACOT13 mRNA level was obviously reduced in renal cystic tissues and WT9-12 cells. Meanwhile, GSEA results showed that compared to the low ACOT13 expression group, PI3K-Akt and MAPK signaling pathways were inactivated, and PPAR signaling pathway and fatty acid metabolism were activated in high ACOT13 expression group. Furthermore, overexpression of ACOT13 notably reduced WT9-12 cell proliferation and triggered cell cycle arrest. Moreover, ACOT13 overexpression remarkably triggered apoptosis, increased cleaved caspase 3 protein level, reduced ATP production and induced loss of mitochondrial membrane potential in WT9-12 cells, suggesting that ACOT13 overexpression could trigger mitochondrial-related apoptosis in WT9-12 cells., Conclusions: Collectively, our results showed that overexpression of ACOT13 could suppress WT9-12 cell proliferation and trigger mitochondrial-mediated cell apoptosis, suggesting that ACOT13 may exert a protective role in ADPKD.

Polycystin-2 (PC2) is mutated in ∼15% of patients with autosomal dominant polycystic kidney disease (ADPKD). PC2 belongs to the family of transient receptor potential (TRP) channels and can function as a homotetramer. We investigated whether three disease-associated mutations (F629S, C632R, or R638C) localized in the channel's pore loop alter ion channel properties of human PC2 expressed in Xenopus laevis oocytes. Expression of wild-type (WT) PC2 typically resulted in small but measurable Na + inward currents in the absence of extracellular divalent cations. These currents were no longer observed when individual pore mutations were introduced in WT PC2. Similarly, Na + inward currents mediated by the F604P gain-of-function (GOF) PC2 construct (PC2 F604P) were abolished by each of the three pore mutations. In contrast, when the mutations were introduced in another GOF construct, PC2 L677A N681A, only C632R had a complete loss-of-function effect, whereas significant residual Na + inward currents were observed with F629S (∼15%) and R638C (∼30%). Importantly, the R638C mutation also abolished the Ca 2+ permeability of PC2 L677A N681A and altered its monovalent cation selectivity. To elucidate the molecular mechanisms by which the R638C mutation affects channel function, molecular dynamics (MD) simulations were used in combination with functional experiments and site-directed mutagenesis. Our findings suggest that R638C stabilizes ionic interactions between Na + ions and the selectivity filter residue D643. This probably explains the reduced monovalent cation conductance of the mutant channel. In summary, our data support the concept that altered ion channel properties of PC2 contribute to the pathogenesis of ADPKD., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Alteration of DNA methylation leads to diverse diseases, and the dynamic changes of DNA methylation (DNAm) on sets of CpG dinucleotides in mammalian genomes are termed "DNAm age" and "epigenetic clocks" that can predict chronological age. However, whether and how dysregulation of DNA methylation promotes cyst progression and epigenetic age acceleration in autosomal dominant polycystic kidney disease (ADPKD) remains elusive. Here, we show that DNA methyltransferase 1 (DNMT1) is upregulated in cystic kidney epithelial cells and tissues and that knockout of Dnmt1 and targeting DNMT1 with hydralazine, a safe demethylating agent, delays cyst growth in Pkd1 mutant kidneys and extends life span of Pkd1 conditional knockout mice. With methyl-CpG binding domain (MBD) protein-enriched genome sequencing (MBD-seq), DNMT1 chromatin immunoprecipitation (ChIP)-sequencing and RNA-sequencing analysis, we identified two novel DNMT1 targets, PTPRM and PTPN22 (members of the protein tyrosine phosphatase family). PTPRM and PTPN22 function as mediators of DNMT1 and the phosphorylation and activation of PKD-associated signaling pathways, including ERK, mTOR and STAT3. With whole-genome bisulfide sequencing in kidneys of patients with ADPKD versus normal individuals, we found that the methylation of epigenetic clock-associated genes was dysregulated, supporting that epigenetic age is accelerated in the kidneys of patients with ADPKD. Furthermore, five epigenetic clock-associated genes, including Hsd17b14, Itpkb, Mbnl1, Rassf5 and Plk2, were identified. Thus, the diverse biological roles of these five genes suggest that their methylation status may not only predict epigenetic age acceleration but also contribute to disease progression in ADPKD., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Polycystin-1 (PC-1) and PC-2 form a heteromeric ion channel complex that is abundantly expressed in primary cilia of renal epithelial cells. This complex functions as a non-selective cation channel, and mutations within the polycystin complex cause autosomal dominant polycystic kidney disease (ADPKD). The spatial and temporal regulation of the polycystin complex within the ciliary membrane remains poorly understood. Using both whole-cell and ciliary patch-clamp recordings, we identify a cilia-enriched oxysterol, 7β,27-dihydroxycholesterol (DHC), that serves as a necessary activator of the polycystin complex. We further identify an oxysterol-binding pocket within PC-2 and showed that mutations within this binding pocket disrupt 7β,27-DHC-dependent polycystin activation. Pharmacologic and genetic inhibition of oxysterol synthesis reduces channel activity in primary cilia. In summary, our findings reveal a regulator of the polycystin complex. This oxysterol-binding pocket in PC-2 may provide a specific target for potential ADPKD therapeutics., (© 2024. The Author(s).)

Background: Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic kidney disorder. While metformin has demonstrated the ability to inhibit cyst growth in animal models of ADPKD via activation of adenosine monophosphate-activated protein kinase (AMPK), its effectiveness in humans is limited due to its low potency. This study explored the impact of HL156A, a new and more potent AMPK activator, in a mouse model of ADPKD., Methods: To investigate whether HL156A inhibits the proliferation of renal cyst cells in ADPKD in vitro, exogenous human telomerase reverse transcriptase (hTERT)-immortalized renal cyst cells from ADPKD patients were treated with HL156A, and an MTT (dimethylthiazol-diphenyltetrazolium bromide) assay was performed. To assess the cyst-inhibitory effect of HL156A in vivo, we generated Pkd1 conditional knockout (KO) mice with aquaporin 2 (AQP2)-Cre, which selectively expresses Cre recombinase in the collecting duct. The effectiveness of HL156A in inhibiting cyst growth and improving renal function was confirmed by measuring the number of cysts and blood urea nitrogen (BUN) levels in the collecting duct-specific Pkd1 KO mice., Results: When cyst cells were treated with up to 20 µM of metformin or HL156A, HL156A reduced cell viability by 25% starting at a concentration of 5 µM, whereas metformin showed no effect. When AQP2-Cre male mice were crossed with Pkd1 flox/flox female mice, and when AQP2-Cre female mice were crossed with Pkd1 flox/flox male mice, the number of litters produced by both groups was comparable. In collecting duct-specific Pkd1 KO mice, HL156A was found to inhibit cyst growth, reducing both the number and size of cysts. Furthermore, it was confirmed that kidney function improved as HL156A treatment led to a reduction in elevated BUN levels. Lastly, it was observed that the increase in AMPK phosphorylation induced by HL156A decreased ERK phosphorylation and α-SMA expression., Conclusion: HL156A has potential as a drug that can restore kidney function in ADPKD patients by inhibiting cyst growth.

WT 9-12 is one of the cell lines commonly used for autosomal dominant polycystic kidney disease (ADPKD) studies. Previous studies had described the PKD gene mutations and polycystin expression in WT 9-12. Nonetheless, the mutations occurring in other ADPKD-associated genes have not been investigated. This study aims to revisit these mutations and protein profile of WT 9-12. Whole genome sequencing verified the presence of truncation mutation at amino acid 2556 (Q2556X) in PKD1 gene of WT 9-12. Besides, those variations with high impacts included single nucleotide polymorphisms (rs8054182, rs117006360, and rs12925771) and insertions and deletions (InDels) (rs145602984 and rs55980345) in PKD1L2; InDel (rs1296698195) in PKD1L3; and copy number variations in GANAB. Protein profiles generated from the total proteins of WT 9-12 and HK-2 cells were compared using isobaric tags for relative and absolute quantitation (iTRAQ) analysis. Polycystin-1 was absent in WT 9-12. The gene ontology enrichment and reactome pathway analyses revealed that the upregulated and downregulated proteins of WT 9-12 relative to HK-2 cell line leaded to signaling pathways related to immune response and amino acid metabolism, respectively. The ADPKD-related mutations and signaling pathways associated with differentially expressed proteins in WT 9-12 may help researchers in cell line selection for their studies., (© 2024 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.)

Mechanical loading is required for bone homeostasis, but the underlying mechanism is still unclear. Our previous studies revealed that the mechanical protein polycystin-1 (PC1, encoded by Pkd1) is critical for bone formation. However, the role of PC1 in bone resorption is unknown. Here, we found that PC1 directly regulates osteoclastogenesis and bone resorption. The conditional deletion of Pkd1 in the osteoclast lineage resulted in a reduced number of osteoclasts, decreased bone resorption, and increased bone mass. A cohort study of 32,500 patients further revealed that autosomal dominant polycystic kidney disease, which is mainly caused by loss-of-function mutation of the PKD1 gene, is associated with a lower risk of hip fracture than those with other chronic kidney diseases. Moreover, mice with osteoclast-specific knockout of Pkd1 showed complete resistance to unloading-induced bone loss. A mechanistic study revealed that PC1 facilitated TAZ nuclear translocation via the C-terminal tail-TAZ complex and that conditional deletion of Taz in the osteoclast lineage resulted in reduced osteoclastogenesis and increased bone mass. Pharmacological regulation of the PC1-TAZ axis alleviated unloading- and estrogen deficiency- induced bone loss. Thus, the PC1-TAZ axis may be a potential therapeutic target for osteoclast-related osteoporosis., (Copyright © 2024 Science China Press. Published by Elsevier B.V. All rights reserved.)

Multiple alterations of cellular metabolism have been documented in experimental studies of autosomal dominant polycystic kidney disease (ADPKD) and are thought to contribute to its pathogenesis. To elucidate the molecular pathways and transcriptional regulators associated with the metabolic changes of renal cysts in ADPKD, we compared global gene expression data from human PKD1 renal cysts, minimally cystic tissues (MCT) from the same patients, and healthy human kidney cortical tissue samples. We found gene expression profiles of PKD1 renal cysts were consistent with the Warburg effect with gene pathway changes favoring increased cellular glucose uptake and lactate production, instead of pyruvate oxidation. Additionally, mitochondrial energy metabolism was globally depressed, associated with downregulation of gene pathways related to fatty acid oxidation (FAO), branched-chain amino acid (BCAA) degradation, the Krebs cycle, and oxidative phosphorylation (OXPHOS) in renal cysts. Activation of mTORC1 and its two target proto-oncogenes, HIF-1α and MYC, was predicted to drive the expression of multiple genes involved in the observed metabolic reprogramming (e.g., GLUT3 , HK1/HK2 , ALDOA , ENO2 , PKM , LDHA/LDHB , MCT4 , PDHA1 , PDK1/3 , MPC1/2 , CPT2 , BCAT1 , NAMPT ); indeed, their predicted expression patterns were confirmed by our data. Conversely, we found AMPK inhibition was predicted in renal cysts. AMPK inhibition was associated with decreased expression of PGC-1α, a transcriptional coactivator for transcription factors PPARα, ERRα, and ERRγ, all of which play a critical role in regulating oxidative metabolism and mitochondrial biogenesis. These data provide a comprehensive map of metabolic pathway reprogramming in ADPKD and highlight nodes of regulation that may serve as targets for therapeutic intervention.

Background: Patients with autosomal dominant polycystic kidney disease (ADPKD) have disproportionately high levels of fibroblast growth factor 23 (FGF-23) for their chronic kidney disease stage, however only a subgroup develops kidney phosphate wasting. We assessed factors associated with phosphate wasting and hypothesize that it identifies patients with more severe disease and predicts disease progression., Methods: We included 604 patients with ADPKD from a multicenter prospective observational cohort (DIPAK; Developing Intervention Strategies to Halt Progression of Autosomal Dominant Polycystic Kidney Disease) in four university medical centers in the Netherlands. We measured parathyroid hormone (PTH) and total plasma FGF-23 levels, and calculated the ratio of tubular maximum reabsorption rate of phosphate to glomerular filtration rate (TmP/GFR) with <0.8 mmol/L defined as kidney phosphate wasting. We analysed the association of TmP/GFR with estimated GFR (eGFR) decline over time and the risk for a composite kidney outcome (≥30% eGFR decline, kidney failure or kidney replacement therapy)., Results: In our cohort (age 48 ± 12 years, 39% male, eGFR 63 ± 28 mL/min/1.73 m2), 59% of patients had phosphate wasting. Male sex [coefficient -0.2, 95% confidence interval (CI) -0.2; -0.1], eGFR (0.002, 95% CI 0.001; 0.004), FGF-23 (0.1, 95% CI 0.03; 0.2), PTH (-0.2, 95% CI -0.3; -0.06) and copeptin (-0.08, 95% CI -0.1; -0.08) were associated with TmP/GFR. Corrected for PTH, FGF-23 and eGFR, every 0.1 mmol/L decrease in TmP/GFR was associated with a greater eGFR decline of 0.2 mL/min/1.73 m2/year (95% CI 0.01; 0.3) and an increased hazard ratio of 1.09 (95% CI 1.01; 1.18) of the composite kidney outcome., Conclusion: Our study shows that in patients with ADPKD, phosphate wasting is prevalent and associated with more rapid disease progression. Phosphate wasting may be a consequence of early proximal tubular dysfunction and insufficient suppression of PTH., (© The Author(s) 2023. Published by Oxford University Press on behalf of the ERA.)

Nephron progenitor cells (NPCs) self-renew and differentiate into nephrons, the functional units of the kidney. Here, manipulation of p38 and YAP activity allowed for long-term clonal expansion of primary mouse and human NPCs and induced NPCs (iNPCs) from human pluripotent stem cells (hPSCs). Molecular analyses demonstrated that cultured iNPCs closely resemble primary human NPCs. iNPCs generated nephron organoids with minimal off-target cell types and enhanced maturation of podocytes relative to published human kidney organoid protocols. Surprisingly, the NPC culture medium uncovered plasticity in human podocyte programs, enabling podocyte reprogramming to an NPC-like state. Scalability and ease of genome editing facilitated genome-wide CRISPR screening in NPC culture, uncovering genes associated with kidney development and disease. Further, NPC-directed modeling of autosomal-dominant polycystic kidney disease (ADPKD) identified a small-molecule inhibitor of cystogenesis. These findings highlight a broad application for the reported iNPC platform in the study of kidney development, disease, plasticity, and regeneration., Competing Interests: Declaration of interests A.P.M. is a scientific advisor or consultant for Novartis, eGENESIS, Trestle Biotherapeutics, GentiBio, and IVIVA Medical. Zhongwei Li, B.H., Z.Z., A.P.M., K.R.H., and N.M.P.-S. have applied for intellectual property protection on the technologies discussed here., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Orexin-A is a neuropeptide product of the lateral hypothalamus that acts on two receptors, OX1R and OX2R. The orexinergic system is involved in feeding, sleep, and pressure regulation. Recently, orexin-A levels have been found to be negatively correlated with renal function. Here, we analyzed orexin-A levels as well as the incidence of SNPs in the hypocretin neuropeptide precursor (HCRT) and its receptors, HCRTR1 and HCRTR2, in 64 patients affected by autosomal dominant polycystic kidney disease (ADPKD) bearing truncating mutations in the PKD1 or PKD2 genes. Twenty-four healthy volunteers constituted the control group. Serum orexin-A was assessed by ELISA, while the SNPs were investigated through Sanger sequencing. Correlations with the main clinical features of PKD patients were assessed. PKD patients showed impaired renal function (mean eGFR 67.8 ± 34.53) and a statistically higher systolic blood pressure compared with the control group ( p < 0.001). Additionally, orexin-A levels in PKD patients were statistically higher than those in healthy controls (477.07 ± 69.42 pg/mL vs. 321.49 ± 78.01 pg/mL; p < 0.001). Furthermore, orexin-A inversely correlated with blood pressure ( p = 0.0085), while a direct correlation with eGFR in PKD patients was found. None of the analyzed SNPs showed any association with orexin-A levels in PKD. In conclusion, our data highlights the emerging role of orexin-A in renal physiology and its potential relevance to PKD. Further research is essential to elucidate the intricate mechanisms underlying orexin-A signaling in renal function and its therapeutic implications for PKD and associated cardiovascular complications.

Autosomal dominant polycystic kidney disease is a genetic kidney disease caused by mutations in the genes PKD1 or PKD2. Its course is characterized by the formation of progressively enlarged cysts in the renal tubules bilaterally. The basic genetic explanation for autosomal dominant polycystic kidney disease is the double-hit theory, and many of its mechanistic issues can be explained by the cilia doctrine. However, the precise molecular mechanisms underpinning this condition's occurrence are still not completely understood. Experimental evidence suggests that aquaporins, a class of transmembrane channel proteins, including aquaporin-1, aquaporin-2, aquaporin-3, and aquaporin-11, are involved in the mechanism of autosomal dominant polycystic kidney disease. Aquaporins are either a potential new target for the treatment of autosomal dominant polycystic kidney disease, and further study into the physiopathological role of aquaporins in autosomal dominant polycystic kidney disease will assist to clarify the disease's pathophysiology and increase the pool of potential treatment options. We primarily cover pertinent findings on aquaporins in autosomal dominant polycystic kidney disease in this review., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Autosomal dominant polycystic kidney disease (ADPKD) is a common monogenic kidney disease. Emerging research indicates that the Notch signaling pathway plays an indispensable role in the pathogenesis of numerous kidney diseases, including ADPKD. Herein, we identified that Notch3 but not other Notch receptors was overexpressed in renal tissues from mice with ADPKD and ADPKD patients. Inhibiting Notch3 with γ-secretase inhibitors, which block a proteolytic cleavage required for Notch3 activation, or shRNA knockdown of Notch3 significantly delayed renal cyst growth in vitro and in vivo. Subsequent mechanistic study elucidated that the cleaved intracellular domain of Notch3 (N3ICD) and Hes1 could bind to the PTEN promoter, leading to transcriptional inhibition of PTEN. This further activated the downstream PI3K-AKT-mTOR pathway and promoted renal epithelial cell proliferation. Overall, Notch3 was identified as a novel contributor to renal epithelial cell proliferation and cystogenesis in ADPKD. We envision that Notch3 represents a promising target for ADPKD treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Patients with autosomal dominant polycystic kidney disease (ADPKD), a genetic disease due to mutations of the PKD1 or PKD2 gene, show signs of complement activation in the urine and cystic fluid, but their pathogenic role in cystogenesis is unclear. We tested the causal relationship between complement activation and cyst growth using a Pkd1KO renal tubular cell line and newly generated conditional Pkd1-/- C3-/- mice. Pkd1-deficient tubular cells have increased expression of complement-related genes (C3, C5, CfB, C3ar, and C5ar1), while the gene and protein expression of complement regulators DAF, CD59, and Crry is decreased. Pkd1-/- C3-/- mice are unable to fully activate the complement cascade and are characterized by a significantly slower kidney cystogenesis, preserved renal function, and reduced intrarenal inflammation compared with Pkd1-/- C3+/+ controls. Transgenic expression of the cytoplasmic C-terminal tail of Pkd1 in Pkd1KO cells lowered C5ar1 expression, restored Daf levels, and reduced cell proliferation. Consistently, both DAF overexpression and pharmacological inhibition of C5aR1 (but not C3aR) reduced Pkd1KO cell proliferation. In conclusion, the loss of Pkd1 promotes unleashed activation of locally produced complement by downregulating DAF expression in renal tubular cells. Increased C5a formation and C5aR1 activation in tubular cells promotes cyst growth, offering a new therapeutic target.

Mouse models of autosomal dominant polycystic kidney disease (ADPKD) show that intact primary cilia are required for cyst growth following the inactivation of polycystin-1. The signaling pathways underlying this process, termed cilia-dependent cyst activation (CDCA), remain unknown. Using translating ribosome affinity purification RNASeq on mouse kidneys with polycystin-1 and cilia inactivation before cyst formation, we identify the differential 'CDCA pattern' translatome specifically dysregulated in kidney tubule cells destined to form cysts. From this, Glis2 emerges as a candidate functional effector of polycystin signaling and CDCA. In vitro changes in Glis2 expression mirror the polycystin- and cilia-dependent changes observed in kidney tissue, validating Glis2 as a cell culture-based indicator of polycystin function related to cyst formation. Inactivation of Glis2 suppresses polycystic kidney disease in mouse models of ADPKD, and pharmacological targeting of Glis2 with antisense oligonucleotides slows disease progression. Glis2 transcript and protein is a functional target of CDCA and a potential therapeutic target for treating ADPKD., (© 2024. The Author(s).)

Introduction: Juxtaglomerular apparatus (JGA)-mediated homeostatic mechanism links to how sodium-glucose cotransporter 2 inhibitors (SGLT2is) slow progression of chronic kidney disease (CKD) and may link to how tolvaptan slows renal function decline in autosomal dominant polycystic kidney disease (ADPKD)., Area Covered: JGA-mediated homeostatic mechanism has been hypothesized based on investigations of tubuloglomerular feedback and renin-angiotensin system. We reviewed clinical trials of SGLT2is and tolvaptan to assess the relationship between this mechanism and these drugs., Expert Opinion: When sodium load to macula densa (MD) increases, MD increases adenosine production, constricting afferent arteriole (Af-art) and protecting glomeruli. Concurrently, MD signaling suppresses renin secretion, increases urinary sodium excretion, and counterbalances reduced sodium filtration. However, when there is marked increase in sodium load per-nephron, as in advanced CKD, MD adenosine production increases, relaxing Af-art and maintaining sodium homeostasis at the expense of glomeruli. The beneficial effects of tolvaptan on renal function in ADPKD may also depend on the JGA-mediated homeostatic mechanisms since tolvaptan inhibits sodium reabsorption in the thick ascending limb.The JGA-mediated homeostatic mechanism regulates Af-arts, constricting to relaxing according to homeostatic needs. Understanding this mechanism may contribute to the development of pharmacotherapeutic compounds and better care for patients with CKD.

PKD1 (polycystin 1) and PKD2 (polycystin 2) are expressed in a variety of different cell types, including arterial smooth muscle and endothelial cells. PKD1 is a transmembrane domain protein with a large extracellular N-terminus that is proposed to act as a mechanosensor and receptor. PKD2 is a member of the transient receptor potential (TRP) channel superfamily which is also termed TRPP1. Mutations in the genes which encode PKD1 and PKD2 lead to autosomal dominant polycystic kidney disease (ADPKD). ADPKD is one of the most prevalent monogenic disorders in humans and is associated with extrarenal and vascular complications, including hypertension. Recent studies have uncovered mechanisms of activation and physiological functions of PKD1 and PKD2 in arterial smooth muscle and endothelial cells. It has also been found that PKD function is altered in the vasculature during ADPKD and hypertension. We will summarize this work and discuss future possibilities for this area of research., (© 2023 John Wiley & Sons Ltd.)

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common monogenic disorder characterized by renal cysts and progressive renal failure. In kidney diseases, adipose tissue undergoes functional changes that have been associated with increased inflammation and insulin resistance mediated by release of adipokines. Adiponectin is involved in various cellular processes, such as energy and inflammatory and oxidative processes. However, it remains to be determined whether adiponectin is involved in the concomitant metabolic dysfunctions present in PKD. In this scenario, we aimed to analyze: (a) PPARγ, ADIPOQ, ADIPOR1 and ADIPOR2 gene variations in 92 ADPKD patients through PCR-Sanger sequencing; and (b) adiponectin levels and its oligomerization state by ELISA and Western Blot. Our results indicated that: (a) 14 patients carried the PPARγ SNP, 29 patients carried the ADIPOQ SNP rs1501299, and 25 patients carried the analyzed ADIPOR1 SNPs. Finally, 82 patients carried ADIPOR2 SNPs; and (b) Adiponectin is statistically lower in ADPKD patients compared to controls, and further statistically lower in ESRD than in non-ESRD patients. An inverse relationship between adiponectin and albumin and between adiponectin and creatinine and a direct relationship between adiponectin and eGFR were found. Interestingly, significantly lower levels of adiponectin were found in patients bearing the ADIPOQ rs1501299 SNP and associated with low levels of eGFR. In conclusion, adiponectin levels and the presence of ADIPOQ rs1501299 genotype are significantly associated with a worse ADPKD phenotype, indicating that both could potentially provide important insights into the disease. Further studies are warranted to understand the pathophysiological role of adiponectin in ADPKD patients.

The dysregulated intracellular cAMP in the kidneys drives cystogenesis and progression in autosomal dominant polycystic kidney disease (ADPKD). Mounting evidence supports that vasopressin V 2 receptor (V 2 R) antagonism effectively reduces cAMP levels, validating this receptor as a therapeutic target. Tolvaptan, an FDA-approved V 2 R antagonist, shows limitations in its clinical efficacy for ADPKD treatment. Therefore, the pursuit of better-in-class V 2 R antagonists with an improved efficacy remains pressing. Herein, we synthesized a set of peptide V 2 R antagonists. Peptide 33 exhibited a high binding affinity for the V 2 R ( K i = 6.1 ± 1.5 nM) and an extended residence time of 20 ± 1 min, 2-fold that of tolvaptan. This prolonged interaction translated into sustained suppression of cAMP production in washout experiments. Furthermore, peptide 33 exhibited improved efficacies over tolvaptan in both ex vivo and in vivo models of ADPKD, underscoring its potential as a promising lead compound for the treatment of ADPKD.

Mutations in PKD1 and PKD2 cause autosomal dominant polycystic kidney disease (ADPKD), which is characterized by the formation of fluid-filled cysts in the kidney. In a subset of ADPKD patients, reduced blood calcium (Ca 2+ ) and magnesium (Mg 2+ ) concentrations are observed. As cystic fluid contains increased ATP concentrations and purinergic signaling reduces electrolyte reabsorption, we hypothesized that inhibiting ATP release could normalize blood Ca 2+ and Mg 2+ levels in ADPKD. Inducible kidney-specific Pkd1 knockout mice (iKsp-Pkd1 -/- ) exhibit hypocalcemia and hypomagnesemia in a precystic stage and show increased expression of the ATP-release channel pannexin-1. Therefore, we administered the pannexin-1 inhibitor brilliant blue-FCF (BB-FCF) every other day from Day 3 to 28 post-induction of Pkd1 gene inactivation. On Day 29, both serum Ca 2+ and Mg 2+ concentrations were reduced in iKsp-Pkd1 -/- mice, while urinary Ca 2+ and Mg 2+ excretion was similar between the genotypes. However, serum and urinary levels of Ca 2+ and Mg 2+ were unaltered by BB-FCF treatment, regardless of genotype. BB-FCF did significantly decrease gene expression of the ion channels Trpm6 and Trpv5 in both control and iKsp-Pkd1 -/- mice. Finally, no renoprotective effects of BB-FCF treatment were observed in iKsp-Pkd1 -/- mice. Thus, administration of BB-FCF failed to normalize serum Ca 2+ and Mg 2+ levels., (© 2024 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Significance Statement: The renal immune infiltrate observed in autosomal polycystic kidney disease contributes to the evolution of the disease. Elucidating the cellular mechanisms underlying the inflammatory response could help devise new therapeutic strategies. Here, we provide evidence for a mechanistic link between the deficiency polycystin-1 and mitochondrial homeostasis and the activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)/stimulator of the interferon genes (STING) pathway. Our data identify cGAS as an important mediator of renal cystogenesis and suggest that its inhibition may be useful to slow down the disease progression., Background: Immune cells significantly contribute to the progression of autosomal dominant polycystic kidney disease (ADPKD), the most common genetic disorder of the kidney caused by the dysregulation of the Pkd1 or Pkd2 genes. However, the mechanisms triggering the immune cells recruitment and activation are undefined., Methods: Immortalized murine collecting duct cell lines were used to dissect the molecular mechanism of cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) activation in the context of genotoxic stress induced by Pkd1 ablation. We used conditional Pkd1 and knockout cGas-/- genetic mouse models to confirm the role of cGAS/stimulator of the interferon genes (STING) pathway activation on the course of renal cystogenesis., Results: We show that Pkd1 -deficient renal tubular cells express high levels of cGAS, the main cellular sensor of cytosolic nucleic acid and a potent stimulator of proinflammatory cytokines. Loss of Pkd1 directly affects cGAS expression and nuclear translocation, as well as activation of the cGAS/STING pathway, which is reversed by cGAS knockdown or functional pharmacological inhibition. These events are tightly linked to the loss of mitochondrial structure integrity and genotoxic stress caused by Pkd1 depletion because they can be reverted by the potent antioxidant mitoquinone or by the re-expression of the polycystin-1 carboxyl terminal tail. The genetic inactivation of cGAS in a rapidly progressing ADPKD mouse model significantly reduces cystogenesis and preserves normal organ function., Conclusions: Our findings indicate that the activation of the cGAS/STING pathway contributes to ADPKD cystogenesis through the control of the immune response associated with the loss of Pkd1 and suggest that targeting this pathway may slow disease progression., (Copyright © 2024 by the American Society of Nephrology.)

Significance Statement: Autosomal dominant polycystic kidney disease (ADPKD) is a devastating disorder caused by mutations in polycystin 1 ( PKD1 ) and polycystin 2 ( PKD2 ). Currently, the mechanism for renal cyst formation remains unclear. Here, we provide convincing and conclusive data in mice demonstrating that Pkd2 deletion in embryonic Aqp2 + progenitor cells (AP), but not in neonate or adult Aqp2 + cells, is sufficient to cause severe polycystic kidney disease (PKD) with progressive loss of intercalated cells and complete elimination of α -intercalated cells, accurately recapitulating a newly identified cellular phenotype of patients with ADPKD. Hence, Pkd2 is a new potential regulator critical for balanced AP differentiation into, proliferation, and/or maintenance of various cell types, particularly α -intercalated cells. The Pkd2 conditional knockout mice developed in this study are valuable tools for further studies on collecting duct development and early steps in cyst formation. The finding that Pkd2 loss triggers the loss of intercalated cells is a suitable topic for further mechanistic studies., Background: Most cases of autosomal dominant polycystic kidney disease (ADPKD) are caused by mutations in PKD1 or PKD2. Currently, the mechanism for renal cyst formation remains unclear. Aqp2 + progenitor cells (AP) (re)generate ≥5 cell types, including principal cells and intercalated cells in the late distal convoluted tubules (DCT2), connecting tubules, and collecting ducts., Methods: Here, we tested whether Pkd2 deletion in AP and their derivatives at different developmental stages is sufficient to induce PKD. Aqp2Cre Pkd2f/f ( Pkd2AC ) mice were generated to disrupt Pkd2 in embryonic AP. Aqp2ECE/+Pkd2f/f ( Pkd2ECE ) mice were tamoxifen-inducted at P1 or P60 to inactivate Pkd2 in neonate or adult AP and their derivatives, respectively. All induced mice were sacrificed at P300. Immunofluorescence staining was performed to categorize and quantify cyst-lining cell types. Four other PKD mouse models and patients with ADPKD were similarly analyzed., Results: Pkd2 was highly expressed in all connecting tubules/collecting duct cell types and weakly in all other tubular segments. Pkd2AC mice had obvious cysts by P6 and developed severe PKD and died by P17. The kidneys had reduced intercalated cells and increased transitional cells. Transitional cells were negative for principal cell and intercalated cell markers examined. A complete loss of α -intercalated cells occurred by P12. Cysts extended from the distal renal segments to DCT1 and possibly to the loop of Henle, but not to the proximal tubules. The induced Pkd2ECE mice developed mild PKD. Cystic α -intercalated cells were found in the other PKD models. AQP2 + cells were found in cysts of only 13/27 ADPKD samples, which had the same cellular phenotype as Pkd2AC mice., Conclusions: Hence, Pkd2 deletion in embryonic AP, but unlikely in neonate or adult Aqp2 + cells (principal cells and AP), was sufficient to cause severe PKD with progressive elimination of α -intercalated cells, recapitulating a newly identified cellular phenotype of patients with ADPKD. We proposed that Pkd2 is critical for balanced AP differentiation into, proliferation, and/or maintenance of cystic intercalated cells, particularly α -intercalated cells., (Copyright © 2024 by the American Society of Nephrology.)

Mutations in the PKD2 gene, which encodes the polycystin-2 (PC2, also called TRPP2) protein, lead to autosomal dominant polycystic kidney disease (ADPKD). As a member of the transient receptor potential (TRP) channel superfamily, PC2 functions as a non-selective cation channel. The activation and regulation of the PC2 channel are largely unknown, and direct binding of small-molecule ligands to this channel has not been reported. In this work, we found that most known small-molecule agonists of the mucolipin TRP (TRPML) channels inhibit the activity of the PC2&#95;F604P, a gain-of-function mutant of the PC2 channel. However, two of them, ML-SA1 and SF-51, have dual regulatory effects, with low concentration further activating PC2&#95;F604P, and high concentration leading to inactivation of the channel. With two cryo-electron microscopy (cryo-EM) structures, a molecular docking model, and mutagenesis results, we identified two distinct binding sites of ML-SA1 in PC2&#95;F604P that are responsible for activation and inactivation, respectively. These results provide structural and functional insights into how ligands regulate PC2 channel function through unusual mechanisms and may help design compounds that are more efficient and specific in regulating the PC2 channel and potentially also for ADPKD treatment., Competing Interests: Competing interests statement:The authors declare no competing interest.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent monogenic renal disease progressing to end-stage renal disease. There is a pressing need for the identification of early ADPKD biomarkers to enable timely intervention and the development of effective therapeutic approaches. Here, we profiled human urinary extracellular vesicles small RNAs by small RNA sequencing in patients with ADPKD and compared their differential expression considering healthy control individuals to identify dysregulated small RNAs and analyze downstream interaction to gain insight about molecular pathophysiology., Methods: This is a cross-sectional study where urine samples were collected from a total of 23 PKD1-ADPKD patients and 28 healthy individuals. Urinary extracellular vesicles were purified, and small RNA was isolated and sequenced. Differentially expressed Small RNA were identified and functional enrichment analysis of the critical miRNAs was performed to identify driver genes and affected pathways., Results: miR-320b, miR-320c, miR-146a-5p, miR-199b-3p, miR-671-5p, miR-1246, miR-8485, miR-3656, has&#95;piR&#95;020497, has&#95;piR&#95;020496 and has&#95;piR&#95;016271 were significantly upregulated in ADPKD patient urine extracellular vesicles and miRNA-29c was significantly downregulated. Five 'driver' target genes (FBRS, EDC3, FMNL3, CTNNBIP1 and KMT2A) were identified., Conclusions: The findings of the present study make significant contributions to the understanding of ADPKD pathogenesis and to the identification of novel biomarkers and potential drug targets aimed at slowing disease progression in ADPKD., (© 2024 The Authors. The Journal of Gene Medicine published by John Wiley & Sons Ltd.)

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic cause of chronic kidney disease and the fourth leading cause of end-stage kidney disease, accounting for over 50% of prevalent cases requiring renal replacement therapy. There is a pressing need for improved therapy for ADPKD. Recent insights into the pathophysiology of ADPKD revealed that cyst cells undergo metabolic changes that up-regulate aerobic glycolysis in lieu of mitochondrial respiration for energy production, a process that ostensibly fuels their increased proliferation. The present work leverages this metabolic disruption as a way to selectively target cyst cells for apoptosis. This small-molecule therapeutic strategy utilizes 11beta-dichloro, a repurposed DNA-damaging anti-tumor agent that induces apoptosis by exacerbating mitochondrial oxidative stress. Here, we demonstrate that 11beta-dichloro is effective in delaying cyst growth and its associated inflammatory and fibrotic events, thus preserving kidney function in perinatal and adult mouse models of ADPKD. In both models, the cyst cells with homozygous inactivation of Pkd1 show enhanced oxidative stress following treatment with 11beta-dichloro and undergo apoptosis. Co-administration of the antioxidant vitamin E negated the therapeutic benefit of 11beta-dichloro in vivo, supporting the conclusion that oxidative stress is a key component of the mechanism of action. As a preclinical development primer, we also synthesized and tested an 11beta-dichloro derivative that cannot directly alkylate DNA, while retaining pro-oxidant features. This derivative nonetheless maintains excellent anti-cystic properties in vivo and emerges as the lead candidate for development., Competing Interests: Competing interests statement:The patent US9982009 was granted to B.I.F., R.G.C., J.M.E., S.V.F., and S.S., and assigned to Massachusetts Institute of Technology and Yale University. The patent covers the use of the 11beta-dipropyl and related compounds as therapeutics for polycystic kidney disease and polycystic liver disease. All other authors declare no competing interests.

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by epithelial proliferation and progressive cyst enlargement. Using a non-targeted high-resolution metabolomics approach, we analyzed biofluids from 36 ADPKD and 18 healthy controls with estimated glomerular filtration rate (eGFR) > 60 ml/min to identify features specific to ADPKD or that associate with disease severity [eGFR or height-corrected total kidney volume (htTKV)]. Multiple pathways differed between ADPKD subjects and controls, with the histidine pathway being the most highly represented. Plasma histidine, urinary N-methylhistamine, methylimidazole-acetaldehyde, and imidazole-acetaldehyde, as well as 3-methylhistidine and anserine were increased, while plasma N-acetylhistamine and urinary imidazole-acetic acid were decreased in ADPKD compared to controls. In ADPKD, urinary histidine and a histidine derivative, urocanate (a precursor of glutamate), were significantly associated. HtTKV and eGFR were inversely associated with urinary glutamine and plasma 4-imidazolone-5-propionic acid, respectively. Supernatant from cultured human ADPKD renal cystic epithelia demonstrated increased aspartate and glutamate levels at 8 and 24 hours compared to primary tubular epithelia (p < 0.001). Following exposure over 48 hours to α-fluromethylhistidine, an inhibitor of histamine production, primary human PKD1 cyst epithelia proliferation increased significantly from baseline (p < 0.01) and greater than non-cystic epithelia (p < 0.05). The histidine ammonia lyase inhibitor nitromethane reversed α-fluromethylhistidine-induced cyst epithelia proliferation indicating a role for glutamate in cyst growth. In conclusion, histidine metabolism is altered preferentially leading to glutamate production and epithelial proliferation in ADPKD and associates with disease severity., (© 2024 The American Clinical and Climatological Association.)

Introduction: It has been reported that rapamycin inhibited inflammation in renal interstitial diseases. We therefore hypothesized that rapamycin could attenuate inflammation in polycystic kidney disease (PKD)., Methods: Han:SPRD rats were treated with rapamycin by daily gavage from 4 weeks to 12 weeks of age at the dosage of 0.5 mg/kg/day (low dose) or 1 mg/kg/day (high dose). WT9-12 human PKD cells were treated with various concentrations of rapamycin., Results: Two-kidney/total body weight ratio and cystic index in Cy/+ kidneys were significantly reduced with the treatment of low-dose rapamycin and further reduced by the treatment with high-dose rapamycin. However, the renal function of Cy/+ rats was equally improved by the treatment with either low-dose or high-dose rapamycin. The renal cell proliferation was significantly decreased in Cy/+ kidneys with the treatment of low-dose rapamycin and was further decreased with the treatment of high-dose rapamycin as examined by Ki67 staining. The phosphorylation of S6K in cystic kidneys was decreased by low-dose rapamycin and further decreased by high-dose rapamycin. Both low-dose and high-dose rapamycin treatment decreased macrophage infiltration and the expression of complement factor B (CFB), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-alpha (TNF-α) to a similar level. The expression of CFB, MCP-1, and TNF-α and phosphorylation of S6K were inhibited in WT9-12 cells treated with 10 nm rapamycin at 24 h and 48 h, respectively. Moreover, the phosphorylation of Akt was not increased by 1 nm and 10 nm of rapamycin and enhanced by 1 μm rapamycin treatment. Interestingly, WT9-12 cell proliferation could be inhibited by 1 μm rapamycin., Conclusion: Low dose of rapamycin could inhibit inflammation and protect renal function in PKD. Inflammation is more sensitive than cell proliferation in response to rapamycin treatment in PKD., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

Renal cyst progression in autosomal dominant polycystic kidney disease (ADPKD) is highly dependent on agents circulating in blood. We have previously shown, using different in vitro models, that one of these agents is the hormone ouabain. By binding to Na + -K + -ATPase (NKA), ouabain triggers a cascade of signal transduction events that enhance ADPKD cyst progression by stimulating cell proliferation, fluid secretion, and dedifferentiation of the renal tubular epithelial cells. Here, we determined the effects of ouabain in vivo. We show that daily administration of ouabain to Pkd1 RC/RC ADPKD mice for 1-5 mo, at physiological levels, augmented kidney cyst area and number compared with saline-injected controls. Also, ouabain favored renal fibrosis; however, renal function was not significantly altered as determined by blood urea nitrogen levels. Ouabain did not have a sex preferential effect, with male and female mice being affected equally. By contrast, ouabain had no significant effect on wild-type mice. In addition, the actions of ouabain on Pkd1 RC/RC mice were exacerbated when another mutation that increased the affinity of NKA for ouabain was introduced to the mice ( Pkd1 RC/RC NKAα1 OS/OS mice). Altogether, this work highlights the role of ouabain as a procystogenic factor in the development of ADPKD in vivo, that the ouabain affinity site on NKA is critical for this effect, and that circulating ouabain is an epigenetic factor that worsens the ADPKD phenotype. NEW & NOTEWORTHY This work shows that the hormone ouabain enhances the progression of autosomal dominant polycystic kidney disease (ADPKD) in vivo. Ouabain augments the size and number of renal cysts, the kidney weight to body weight ratio, and kidney fibrosis in an ADPKD mouse model. The Na + -K + -ATPase affinity for ouabain plays a critical role in these effects. In addition, these outcomes are independent of the sex of the mice.

Autosomal dominant polycystic kidney disease (ADPKD) has cancer-like pathophysiology. In this study, we aimed to investigate the phenotype of peripheral blood (PB) T cell subsets and immune checkpoint inhibitor expression of ADPKD patients across different chronic kidney disease (CKD) stages. Seventy-two patients with ADPKD and twenty-three healthy controls were included in the study. The patients were grouped into five different CKD stages, according to glomerular filtration rate (GFR). PB mononuclear cells were isolated and T cell subsets and cytokine production were examined by flow cytometry. CRP levels, height-adjusted total kidney volume (htTKV), rate of hypertension (HT) differed significantly across different GFR stages in ADPKD. T cell phenotyping revealed significantly elevated CD3+ T cells, CD4+, CD8+, double-negative, and double-positive subsets and significantly elevated IFN-γ and TNF-α producing subsets of CD4+, CD8+ cells. The expression of checkpoint inhibitors CTLA-4, PD-1, and TIGIT by T cell subsets was also increased to various extent. Additionally, Treg cell numbers and suppressive markers CTLA-4, PD-1, and TIGIT were significantly elevated in ADPKD patients' PB. Treg CTLA4 expression and CD4CD8DP T cell frequency in patients with HT were significantly higher. Lastly, HT and increased htTKV and higher frequency of PD1+ CD8SP were found to be risk factors for rapid disease progression. Our data provide the first detailed analyses of checkpoint inhibitor expression by PB T cell subsets during stages of ADPKD, and that a higher frequency of PD1+ CD8SP cells is associated with rapid disease progression., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In the kidney, the flow rate of the pro-urine through the renal tubules is highly variable. The tubular epithelial cells sense these variations in pro-urinary flow rate in order to regulate various physiological processes, including electrolyte reabsorption. One of the mechanosensitive pathways activated by flow is the release of ATP, which can then act as a autocrine or paracrine factor. Increased ATP release is observed in various kidney diseases, among others autosomal dominant polycystic kidney disease (ADPKD). However, the mechanisms underlying flow-induced ATP release in the collecting duct, especially in the inner medullary collecting duct, remain understudied. Using inner medullary collecting duct 3 (IMCD3) cells in a microfluidic setup, we show here that administration of a high flow rate for 1 min results in an increased ATP release compared to a lower flow rate. Although the ATP release channel pannexin-1 contributed to flow-induced ATP release in Pkd1 -/- IMCD3 cells, it did not in wildtype IMCD3 cells. In addition, flow application increased the expression of the putative ATP release channel connexin-30.3 (CX30.3) in wildtype and Pkd1 -/- IMCD3 cells. However, CX30.3 knockout IMCD3 cells exhibited a similar flow-induced ATP release as wildtype IMCD3 cells, suggesting that CX30.3 does not drive flow-induced ATP release in wildtype IMDC3 cells. Collectively, our results show differential mechanisms underlying flow-induced ATP release in wildtype and Pkd1 -/- IMCD3 cells and further strengthen the link between ADPKD and pannexin-1-dependent ATP release., (© 2023 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Mutations in the gene encoding polycystin-1 (PC1) are the most common cause of autosomal dominant polycystic kidney disease (ADPKD). Cysts in ADPKD exhibit a Warburg-like metabolism characterized by dysfunctional mitochondria and aerobic glycolysis. PC1 is an integral membrane protein with a large extracellular domain, a short C-terminal cytoplasmic tail and shares structural and functional similarities with G protein-coupled receptors. Its exact function remains unclear. The C-terminal cytoplasmic tail of PC1 undergoes proteolytic cleavage, generating soluble fragments that are overexpressed in ADPKD kidneys. The regulation, localization, and function of these fragments is poorly understood. Here, we show that a ∼30 kDa cleavage fragment (PC1-p30), comprising the entire C-terminal tail, undergoes rapid proteasomal degradation by a mechanism involving the von Hippel-Lindau tumor suppressor protein. PC1-p30 is stabilized by reactive oxygen species, and the subcellular localization is regulated by reactive oxygen species in a dose-dependent manner. We found that a second, ∼15 kDa fragment (PC1-p15), is generated by caspase cleavage at a conserved site (Asp-4195) on the PC1 C-terminal tail. PC1-p15 is not subject to degradation and constitutively localizes to the mitochondrial matrix. Both cleavage fragments induce mitochondrial fragmentation, and PC1-p15 expression causes impaired fatty acid oxidation and increased lactate production, indicative of a Warburg-like phenotype. Endogenous PC1 tail fragments accumulate in renal cyst-lining cells in a mouse model of PKD. Collectively, these results identify novel mechanisms regarding the regulation and function of PC1 and suggest that C-terminal PC1 fragments may be involved in the mitochondrial and metabolic abnormalities observed in ADPKD., Competing Interests: Conflicts of interest T. W. is an inventor on issued and pending patents filed by the University of California, Santa Barbara related to PKD, is a shareholder of Santa Barbara Nutrients, Inc, and holds a managerial position, is a scientific advisor and shareholder of Chinook Therapeutics, received research funding from Chinook Therapeutics, and received speaker fees from Sanofi Genzyme. And also add the following sentence: All other authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Defects in the primary cilium are associated with autosomal dominant polycystic kidney disease (ADPKD). We used a combination of animal models, Western blotting, and confocal microscopy and discovered that CFTR and polycystin 2 (PC2) are both colocalized to the cilium in normal kidneys, with the levels of both being decreased in cystic epithelia. Cilia were longer in CFTR-null mice and in cystic cells in our ADPKD animal models. We examined septin 2, known to play a role in cilia length, to act as a diffusion barrier and to serve as an enhancer of proliferation. We found that septin 2 protein levels were upregulated and colocalized strongly with CFTR in cystic cells. Application of VX-809, the CFTR corrector, restored CFTR and PC2 toward normal in the cilia, decreased the protein levels of septin 2, and drastically reduced septin 2 colocalization with CFTR. Our data suggest that CFTR is present in the cilia and plays a role there, perhaps through its conductance of Cl - . We also postulate that septin 2 is important for localizing CFTR to the apical membrane in cystic epithelia. NEW & NOTEWORTHY CFTR is present in the primary cilia together with polycystin 2 (PC2). Ablation of CFTR makes cilia longer suggesting that CFTR plays a role there, perhaps through its conductance of Cl.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic kidney disease and is characterized by the formation of renal cysts and the eventual development of end-stage kidney disease. One approach to treating ADPKD is through inhibition of the mammalian target of rapamycin (mTOR) pathway, which has been implicated in cell overproliferation, contributing to renal cyst expansion. However, mTOR inhibitors, including rapamycin, everolimus, and RapaLink-1, have off-target side effects including immunosuppression. Thus, we hypothesized that the encapsulation of mTOR inhibitors in drug delivery carriers that target the kidneys would provide a strategy that would enable therapeutic efficacy while minimizing off-target accumulation and associated toxicity. Toward eventual in vivo application, we synthesized cortical collecting duct (CCD) targeted peptide amphiphile micelle (PAM) nanoparticles and show high drug encapsulation efficiency (>92.6%). In vitro analysis indicated that drug encapsulation into PAMs enhanced the anti-proliferative effect of all three drugs in human CCD cells. Analysis of in vitro biomarkers of the mTOR pathway via western blotting confirmed that PAM encapsulation of mTOR inhibitors did not reduce their efficacy. These results indicate that PAM encapsulation is a promising way to deliver mTOR inhibitors to CCD cells and potentially treat ADPKD. Future studies will evaluate the therapeutic effect of PAM-drug formulations and ability to prevent off-target side effects associated with mTOR inhibitors in mouse models of ADPKD., Competing Interests: Declaration of competing interests The authors declare no financial interests/personal relationships which may be considered as potential competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Renal cystogenesis is the pathological hallmark of autosomal dominant polycystic kidney disease, caused by PKD1 and PKD2 mutations. The formation of renal cysts is a common manifestation in ciliopathies, a group of syndromic disorders caused by mutation of proteins involved in the assembly and function of the primary cilium. Cystogenesis is caused by the derailment of the renal tubular architecture and tissue deformation that eventually leads to the impairment of kidney function. However, the biomechanical imbalance of cytoskeletal forces that are altered in cells with Pkd1 mutations has never been investigated, and its nature and extent remain unknown. In this computational study, we explored the feasibility of various biomechanical drivers of renal cystogenesis by examining several hypothetical mechanisms that may promote morphogenetic markers of cystogenesis. Our objective was to provide physics-based guidance for our formulation of hypotheses and our design of experimental studies investigating the role of biomechanical disequilibrium in cystogenesis. We employed the finite element method to explore the role of (1) wild-type versus mutant cell elastic modulus; (2) contractile stress magnitude in mutant cells; (3) localization and orientation of contractile stress in mutant cells; and (4) sequence of cell contraction and cell proliferation. Our objective was to identify the factors that produce the characteristic tubular cystic growth. Results showed that cystogenesis occurred only when mutant cells contracted along the apical-basal axis, followed or accompanied by cell proliferation, as long as mutant cells had comparable or lower elastic modulus than wild-type cells, with their contractile stresses being significantly greater than their modulus. Results of these simulations allow us to focus future in vitro and in vivo experimental studies on these factors, helping us formulate physics-based hypotheses for renal tubule cystogenesis., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the formation of fluid-filled cysts within the kidney due to mutations in PKD1 or PKD2. Although the disease remains incompletely understood, one of the factors associated with ADPKD progression is the release of nucleotides (including ATP), which can initiate autocrine or paracrine purinergic signaling by binding to their receptors. Recently, we and others have shown that increased extracellular vesicle (EVs) release from PKD1 knockout cells can stimulate cyst growth through effects on recipient cells. Given that EVs are an important communicator between different nephron segments, we hypothesize that EVs released from PKD1 knockout distal convoluted tubule (DCT) cells can stimulate cyst growth in the downstream collecting duct (CD). Here, we show that administration of EVs derived from Pkd1 -/- mouse distal convoluted tubule (mDCT15) cells result in a significant increase in extracellular ATP release from Pkd1 -/- mouse inner medullary collecting duct (iMCD3) cells. In addition, exposure of Pkd1 -/- iMCD3 cells to EVs derived from Pkd1 -/- mDCT15 cells led to an increase in the phosphorylation of the serine/threonine-specific protein Akt, suggesting activation of proliferative pathways. Finally, the exposure of iMCD3 Pkd1 -/- cells to mDCT15 Pkd1 -/- EVs increased cyst size in Matrigel. These findings indicate that EVs could be involved in intersegmental communication between the distal convoluted tubule and the collecting duct and potentially stimulate cyst growth., (© 2023 Federation of American Societies for Experimental Biology.)

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disorder of adults, characterized by uncontrolled cysts formation that causes a gradual impairment of kidney function. We generated a human induced pluripotent stem cell (hiPSC) line from the urinary cells of a patient diagnosed with ADPKD using a non-integrating Epi5™ Episomal iPSC reprogramming strategy. Characterization of the cell line was performed regarding their undifferentiated status, differentiation potential, and quality control for karyotypic integrity, identity, and clearance of reprogramming vectors. The newly derived hiPSC line, namely BCRTi007-A, can be used in vitro for disease modeling of ADPKD as well as testing for novel therapeutic approaches., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Autosomal dominant polycystic kidney disease (ADPKD) mainly results from mutations in the PKD1 gene, which encodes polycystin 1. It is the most common inherited kidney disease and is characterized by a progressive bilateral increase in cyst number and size, often leading to kidney failure. The cellular energy sensor and regulator adenosine monophosphate stimulated protein kinase (AMPK) has been implicated as a promising new therapeutic target. To address this hypothesis, we determined the effects of a potent and selective clinical stage direct allosteric AMPK activator, PXL770, in canine and patient-derived 3D cyst models and an orthologous mouse model of ADPKD. PXL770 induced AMPK activation and dose-dependently reduced cyst growth in principal-like Madin-Darby Canine Kidney cells stimulated with forskolin and kidney epithelial cells derived from patients with ADPKD stimulated with desmopressin. In an inducible, kidney epithelium-specific Pkd1 knockout mouse model, PXL770 produced kidney AMPK pathway engagement, prevented the onset of kidney failure (reducing blood urea by 47%), decreased cystic index by 26% and lowered the kidney weight to body weight ratio by 35% compared to untreated control Pkd1 knockout mice. These effects were accompanied by a reduction of markers of cell proliferation (-48%), macrophage infiltration (-53%) and tissue fibrosis (-37%). Thus, our results show the potential of direct allosteric AMPK activation in the treatment of ADPKD and support the further development of PXL770 for this indication., (Copyright © 2023 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Development of autosomal dominant polycystic kidney disease (ADPKD) involves renal epithelial cell abnormalities. Cystic fluid contains a high level of ATP that, among other effects, leads to a reduced reabsorption of electrolytes in cyst-lining cells, and thus results in cystic fluid accumulation. Earlier, we demonstrated that Pkd1 RC/RC mice, a hypomorphic model of ADPKD, exhibit increased expression of pannexin-1, a membrane channel capable of ATP release. In the current study, we found that human ADPKD cystic epithelia have higher pannexin-1 abundance than normal collecting ducts. We hypothesized that inhibition of pannexin-1 function with probenecid can be used to attenuate ADPKD development. Renal function in male and female Pkd1 RC/RC and control mice was monitored between 9 and 20 months of age. To test the therapeutic effects of probenecid (a uricosuric agent and a pannexin-1 blocker), osmotic minipumps were implanted in male and female Pkd1 RC/RC mice, and probenecid or vehicle was administered for 42 days until 1 year of age. Probenecid treatment improved glomerular filtration rates and slowed renal cyst formation in male mice (as shown in histopathology). The mechanistic effects of probenecid on sodium reabsorption and fluid transport were tested on polarized mpkCCD cl4 cells subjected to short-circuit current measurements, and in 3D cysts grown in Matrigel. In the mpkCCD cl4 epithelial cell line, probenecid elicited higher ENaC currents and attenuated in vitro cyst formation, indicating lower sodium and less fluid retention in the cysts. Our studies open new avenues of research into targeting pannexin-1 in ADPKD pathology., (© 2023 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Polycystic kidney disease is a disorder of renal epithelial growth and differentiation. Transcription factor EB (TFEB), a master regulator of lysosome biogenesis and function, was studied for a potential role in this disorder. Nuclear translocation and functional responses to TFEB activation were studied in three murine models of renal cystic disease, including knockouts of folliculin , folliculin interacting proteins 1 and 2 , and polycystin-1 ( Pkd1 ) as well as in mouse embryonic fibroblasts lacking Pkd1 and three-dimensional cultures of Madin-Darby canine kidney cells. Nuclear translocation of Tfeb characterized cystic but not noncystic renal tubular epithelia in all three murine models as both an early and sustained response to cyst formation. Epithelia expressed elevated levels of Tfeb-dependent gene products, including cathepsin B and glycoprotein nonmetastatic melanoma protein B. Nuclear Tfeb translocation was observed in mouse embryonic fibroblasts lacking Pkd1 but not wild-type fibroblasts. Pkd1 knockout fibroblasts were characterized by increased Tfeb-dependent transcripts, lysosomal biogenesis and repositioning, and increased autophagy. The growth of Madin-Darby canine kidney cell cysts was markedly increased following exposure to the TFEB agonist compound C1, and nuclear Tfeb translocation was observed in response to both forskolin and compound C1 treatment. Nuclear TFEB also characterized cystic epithelia but not noncystic tubular epithelia in human patients with autosomal dominant polycystic kidney disease. Noncanonical activation of TFEB is characteristic of cystic epithelia in multiple models of renal cystic disease including those associated with loss of Pkd1 . Nuclear TFEB translocation is functionally active in these models and may be a component of a general pathway contributing to cystogenesis and growth. NEW & NOTEWORTHY Changes in epithelial cell metabolism are important in renal cyst development. The role of TFEB, a transcriptional regulator of lysosomal function, was explored in several models of renal cystic disease and human ADPKD tissue sections. Nuclear TFEB translocation was uniformly observed in cystic epithelia in each model of renal cystic disease examined. TFEB translocation was functionally active and associated with lysosomal biogenesis and perinuclear repositioning, increased TFEB-associated protein expression, and activation of autophagic flux. Compound C1, a TFEB agonist, promoted cyst growth in 3-D cultures of MDCK cells. Nuclear TFEB translocation is an underappreciated signaling pathway for cystogenesis that may represent a new paradigm for cystic kidney disease.

The cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB)-glycogen synthase kinase 3β (GSK3β) signaling pathway was reported to be involved in the progression of autosomal dominant polycystic kidney diseases (ADPKD). We designed and synthesized pyrrole-imidazole (PI) polyamides as novel gene-silencers to prevent binding of CREB on the GSK3β gene promoter and examined the effects of the PI polyamides on proliferation and cyst formation of mouse collecting duct M1 cells. The GSK3β PI polyamides significantly inhibited expression of GSK3β mRNA in M1 cells with forskolin. To obtain cells as collecting ducts from ADPKD, the PKD1 gene was knocked down by shRNA. Lower concentrations of forskolin significantly stimulated proliferation of PKD1 knock-down M1 cells, whereas GSK3β PI polyamide significantly inhibited proliferation of PKD1 knock-down M1 cells with forskolin. Stimulation with forskolin for 5 days induced enlargement of cysts from PKD1 knock-down M1 cells. GSK3β PI polyamides significantly suppressed the enlargement of cysts with forskolin stimulation in PKD1 knock-down M1 cells. Thus, the present study showed that transcriptional suppression of the GSK3β gene by PI polyamides targeting the binding of CREB inhibited the proliferation and cyst formation of PKD1 knock-down M1 cells. The GSK3β PI polyamides may potentially be novel medicines for ADPKD., Competing Interests: Declaration of competing interest The authors declare there are no potential conflicts of interest relevant to this article., (Copyright © 2023 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease. Cyst development in ADPKD involves abnormal epithelial cell proliferation, which is affected by the primary cilia-mediated signal transduction in the epithelial cells. Thus, primary cilium has been considered as a therapeutic target for ADPKD. Since ADPKD exhibits many pathological features similar to solid tumors, we investigated whether targeting primary cilia using anti-tumor agents could alleviate the development of ADPKD. Twenty-four natural compounds with anti-tumor activity were screened in MDCK cyst model, and 1-Indanone displayed notable inhibition on renal cyst growth without cytotoxicity. This compound also inhibited cyst development in embryonic kidney cyst model. In neonatal kidney-specific Pkd1 knockout mice, 1-Indanone remarkably slowed down kidney enlargement and cyst expansion. Furthermore, we demonstrated that 1-Indanone inhibited the abnormal elongation of cystic epithelial cilia by promoting tubulin polymerization and significantly down-regulating expression of anterograde transport motor protein KIF3A and IFT88. Moreover, we found that 1-Indanone significantly down-regulated ciliary coordinated Wnt/β-catenin, Hedgehog signaling pathways. These results demonstrate that 1-Indanone inhibits cystic cell proliferation by reducing abnormally prolonged cilia length in cystic epithelial cells, suggesting that 1-Indanone may hold therapeutic potential to retard cyst development in ADPKD., (© 2022. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.)