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Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations to PKD1 or PKD2, triggering progressive cystogenesis and typically leading to end-stage renal disease in midlife. The phenotypic spectrum, however, ranges from in utero onset to adequate renal function at old age. Recent patient data suggest that the disease is dosage dependent, where incompletely penetrant alleles influence disease severity. Here, we have developed a knockin mouse model matching a likely disease variant, PKD1 p.R3277C (RC), and have proved that its functionally hypomorphic nature modifies the ADPKD phenotype. While Pkd1+/null mice are normal, Pkd1RC/null mice have rapidly progressive disease, and Pkd1RC/RC animals develop gradual cystogenesis. These models effectively mimic the pathophysiological features of in utero-onset and typical ADPKD, respectively, correlating the level of functional Pkd1 product with disease severity, highlighting the dosage dependence of cystogenesis. Additionally, molecular analyses identified p.R3277C as a temperature-sensitive folding/trafficking mutant, and length defects in collecting duct primary cilia, the organelle central to PKD pathogenesis, were clearly detected for the first time to our knowledge in PKD1. Altogether, this study highlights the role that in trans variants at the disease locus can play in phenotypic modification of dominant diseases and provides a truly orthologous PKD1 model, optimal for therapeutic testing.

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease that can lead to kidney failure. Mutations in the proteins PKD1 and PKD2 are linked to the disease, but the function of these proteins remains unclear, both in physiology and disease. PKD1 has been implicated in the sensing of chemical and mechanical force stimuli, and PKD2 is proposed to be a calcium ion channel. Su et al. show that the transmembrane regions form a PKD1-PKD2 complex assembled in a 1:3 ratio. Their high-resolution cryo–electron microscopy structure confirms that the complex adopts transient receptor potential channel architecture, with some distinctive features. Mapping disease-causing mutations onto the structure suggests that pathogenesis may come from incorrect folding or trafficking of the complex rather than from disruption of channel activity. Science , this issue p. eaat9819 This structure provides a framework for further investigations into a complex involved in polycystic kidney disease. Mutations in two genes, PKD1 and PKD2 , account for most cases of autosomal dominant polycystic kidney disease, one of the most common monogenetic disorders. Here we report the 3.6-angstrom cryo–electron microscopy structure of truncated human PKD1-PKD2 complex assembled in a 1:3 ratio. PKD1 contains a voltage-gated ion channel (VGIC) fold that interacts with PKD2 to form the domain-swapped, yet noncanonical, transient receptor potential (TRP) channel architecture. The S6 helix in PKD1 is broken in the middle, with the extracellular half, S6a, resembling pore helix 1 in a typical TRP channel. Three positively charged, cavity-facing residues on S6b may block cation permeation. In addition to the VGIC, a five–transmembrane helix domain and a cytosolic PLAT domain were resolved in PKD1. The PKD1-PKD2 complex structure establishes a framework for dissecting the function and disease mechanisms of the PKD proteins.

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. Cyst growth in autosomal dominant polycystic kidney disease (ADPKD) is driven by unknown molecular signals that require the presence of intact primary cilia in the absence of the PKD gene products. Here, the authors show that the transcription factor Glis2 is a key effector of this cilia dependent cyst growth pathway and a potential target for therapy in ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent potentially lethal monogenic disorder. Mutations in the PKD1 gene, which encodes polycystin-1 (PC1), account for approximately 78% of cases. PC1 is a large 462-kDa protein that undergoes cleavage in its N and C-terminal domains. C-terminal cleavage produces fragments that translocate to mitochondria. We show that transgenic expression of a protein corresponding to the final 200 amino acid (aa) residues of PC1 in two Pkd1 -KO orthologous murine models of ADPKD suppresses cystic phenotype and preserves renal function. This suppression depends upon an interaction between the C-terminal tail of PC1 and the mitochondrial enzyme Nicotinamide Nucleotide Transhydrogenase (NNT). This interaction modulates tubular/cyst cell proliferation, the metabolic profile, mitochondrial function, and the redox state. Together, these results suggest that a short fragment of PC1 is sufficient to suppress cystic phenotype and open the door to the exploration of gene therapy strategies for ADPKD. Mutations in the gene encoding PC1 cause ADPKD, a common genetic renal disease. Here, the authors show that expression of the C-terminal 200 amino acids of the large PC1 protein in mouse models of ADPKD suppresses cystic disease through an interaction with the mitochondrial enzyme NNT.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by germline mutations of PKD1 or PKD2 on one allele and a somatic mutation inactivating the remaining normal allele. However, if and how null ADPKD gene renal epithelial cells affect the biology and function of neighboring cells, including heterozygous renal epithelial cells, fibroblasts and macrophages during cyst initiation and expansion remains unknown. Here we address this question with a “cystic extracellular vesicles/exosomes theory”. We show that cystic cell derived extracellular vesicles and urinary exosomes derived from ADPKD patients promote cyst growth in Pkd1 mutant kidneys and in 3D cultures. This is achieved by: 1) downregulation of Pkd1 gene expression and upregulation of specific miRNAs, resulting in the activation of PKD associated signaling pathways in recipient renal epithelial cells and tissues; 2) the activation of fibroblasts; and 3) the induction of cytokine expression and the recruitment of macrophages to increase renal inflammation in cystic kidneys. Inhibition of exosome biogenesis/release with GW4869 significantly delays cyst growth in aggressive and milder ADPKD mouse models, suggesting that targeting exosome secretion has therapeutic potential for ADPKD. Autosomal dominant polycystic kidney disease is characterized by the formation of cysts in the kidney. Here the authors show that cystic extracellular vesicles/exosomes play a critical role in regulating the biology and function of adjacent cells, including renal epithelial cells, fibroblasts and macrophages, and contribute to renal cyst growth.

Autosomal-Dominant Polycystic Kidney Disease, ADPKD, is the most common genetic kidney disease affecting 1:1000 people worldwide. It is caused by mutations in the PKD1 (~ 80%) or PKD2 gene (~ 15%). Although the germline mutation is inherited in dominant fashion, disabling the second allele is required for emergence of clonal cysts. Presently, no cure exists for ADPKD. In approximately 30% of patients, the heritable ADPKD mutation involves a single nucleotide substitution that converts the normal mRNA triplet encoding an amino acid into a Premature Termination Codon (PTC). The translation machinery poses at the PTC and detaches from the mutant mRNA; the unstable transcript and protein are degraded. Certain aminoglycosides bind to the mammalian ribosome and relax translational fidelity, permitting continued translation and production of a full-length protein. In this study, we tested the ability of aminoglycosides to induce readthrough of the PTC codons in the human PKD1 gene and ascertained the effect of these drugs on pathologic features of PKD1 mutant cells. We report that aminoglycosides induce 8–25% expression of full-length Polycystin1 ( PKD1 gene product) and significantly improve aberrant cell adhesion and cell signaling. Based on our observations, we propose that aminoglycoside readthrough drugs show potential as therapeutic agents for ADPKD.

Autosomal dominant polycystic kidney disease (ADPKD), among the most common human genetic conditions and a frequent etiology of kidney failure, is primarily caused by heterozygous PKD1 mutations. Kidney cyst formation occurs when PKD1 dosage falls below a critical threshold. However, no framework exists to harness the remaining allele or reverse PKD1 decline. Here, we show that mRNAs produced by the noninactivated PKD1 allele are repressed via their 3′-UTR miR-17 binding element. Eliminating this motif ( Pkd1 ∆17 ) improves mRNA stability, raises Polycystin-1 levels, and alleviates cyst growth in cellular, ex vivo, and mouse PKD models. Remarkably, Pkd2 is also inhibited via its 3′-UTR miR-17 motif, and Pkd2 ∆17 -induced Polycystin-2 derepression retards cyst growth in Pkd1 -mutant models. Moreover, acutely blocking Pkd1/2 cis-inhibition, including after cyst onset, attenuates murine PKD. Finally, modeling PKD1 ∆17 or PKD2 ∆17 alleles in patient-derived primary ADPKD cultures leads to smaller cysts, reduced proliferation, lower pCreb1 expression, and improved mitochondrial membrane potential. Thus, evading 3′-UTR cis-interference and enhancing PKD1/2 mRNA translation is a potentially mutation-agnostic ADPKD-arresting approach. ADPKD, a common aetiology of kidney failure, is caused by heterozygous PKD1 or PKD2 mutations. Here the authors show that preventing 3′-UTR cis-inhibition of mRNAs produced by the non-inactivated PKD1/2 alleles ameliorates preclinical ADPKD.

Aurora Kinase A (AURKA) promotes cell proliferation and is overexpressed in different types of polycystic kidney disease (PKD). To understand AURKA’s role in regulating renal cyst development we conditionally deleted the gene in mouse models of Autosomal Dominant PKD (ADPKD) and Joubert Syndrome, caused by Polycystin 1 ( Pkd1) and Inositol polyphosphate-5-phosphatase E ( Inpp5e ) mutations respectively. We show that while Aurka is dispensable for collecting duct development and homeostasis, its deletion prevents cyst formation in both disease models. Cross-comparison of transcriptional changes implicated AKT signaling in cyst prevention and we show that (i) AURKA and AKT physically interact, (ii) AURKA regulates AKT activity in a kinase-independent manner and (iii) inhibition of AKT can reduce disease severity. AKT activation also regulates Aurka expression, creating a feed-forward loop driving renal cystogenesis. We find that the AURKA kinase inhibitor Alisertib stabilises the AURKA protein, agonizing its cystogenic functions. These studies identify AURKA as a master regulator of renal cyst development in different types of PKD, functioning in-part via AKT. Using different mouse models of Polycystic Kidney Disease, this research demonstrated that deletion of the Aurora Kinase A gene was able to prevent cyst initiation and growth, identifying it as a central regulator of pathogenesis in this condition.

Autosomal dominant polycystic kidney disease (ADPKD) affects more than 500,000 individuals in the United States alone. In most cases, ADPKD is caused by a loss-of-function mutation in the PKD1 gene, which encodes polycystin-1 (PC1). Previous studies reported that PC1 interacts with atypical protein kinase C (aPKC). Here we show that PC1 binds to the ζ isoform of aPKC (PKCζ) and identify two PKCζ phosphorylation sites on PC1’s C-terminal tail. PKCζ expression is down-regulated in patients with ADPKD and orthologous and nonorthologous PKD mouse models. We find that the US Food and Drug Administration–approved drug FTY720 restores PKCζ expression in in vitro and in vivo models of polycystic kidney disease (PKD) and this correlates with ameliorated disease progression in multiple PKD mouse models. Importantly, we show that FTY720 treatment is less effective in PKCζ null versions of these PKD mouse models, elucidating a PKCζ-specific mechanism of action that includes inhibiting STAT3 activity and cyst-lining cell proliferation. Taken together, our results reveal that PKCζ down-regulation is a hallmark of PKD and that its stabilization by FTY720 may represent a therapeutic approach to the treat the disease.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic kidney disease, caused by mutations of the PKD1 and PKD2 genes, characterized by the development of renal cysts and extrarenal complications, such as cardiac hypertrophy. Recently, a revolutionary approach, adeno-associated virus (AAV) delivered CRISPR-Cas9 gene editing, has been developed to treat inherited diseases. However, the use of this technology in kidney diseases in vivo is challenged. In this study, we adapt one of the gene editing systems, adenine base editor (ABE9), to develop a broadly expressed and a kidney-specific promoter mediated base editors, and test the effects of these two systems delivered by AAV9 on preventing disease in humanized Pkd1 RC/RC mice carrying an arginine (R) to cystine (C) mutation that mimics a mutation in ADPKD patients. We show that one dose of the broadly expressed dual ABE9-AAV9 treatment corrects the pathogenic variant in kidneys, hearts and livers, and result in delaying cyst growth, decrease heart hypertrophy and improve liver function. To confirm the specificity of the base editor system in kidneys, we show that one dose of the kidney specific promoter mediated dual-ABE9-AAV9 treatment corrects the Pkd1 gene mutation in the kidney, and not in the heart, resulting in delaying cyst growth in Pkd1 RC/RC kidneys, supporting a promising strategy of using base editor to target specific organs. Treatment with ABE9 base editors mediated by either the broadly expressed or kidney specific promoter increased the survival rate of Pkd1 RC/null mice. These preclinical studies support a potential that single-dose genetic therapies may be through the correction of pathogenic variants to prevent ADPKD development in the clinic. ADPKD is a genetic kidney disease caused by mutations in PKD1 . Here, the authors develop broadly expressed and kidney specific promoter mediated adenine base editors to correct point mutation of Pkd1 gene, rescuing pathology in a humanized mouse model.