In vivo Polycystin-1 interactome using a novel Pkd1 knock-in mouse model.

PKD1 is the most commonly mutated gene causing autosomal dominant polycystic kidney disease (ADPKD). It encodes Polycystin-1 (PC1), a putative membrane protein that undergoes a set of incompletely characterized post-transcriptional cleavage steps and has been reported to localize in multiple subcellular locations, including the primary cilium and mitochondria. However, direct visualization of PC1 and detailed characterization of its binding partners remain challenging.

Mechanisms of Cyst Development in Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease is the most common inherited cause of end-stage kidney disease worldwide. Most cases result from mutation of either of 2 genes, PKD1 and PKD2, which encode proteins that form a probable receptor/channel complex. Studies suggest that a loss of function of the complex below an indeterminate threshold triggers cyst initiation, which ultimately results in dysregulation of multiple metabolic processes and downstream pathways and subsequent cyst growth.

Analysis of ESAFORM 2021 cup drawing benchmark of an Al alloy, critical factors for accuracy and efficiency of FE simulations.

This article details the ESAFORM Benchmark 2021. The deep drawing cup of a 1 mm thick, AA 6016-T4 sheet with a strong cube texture was simulated by 11 teams relying on phenomenological or crystal plasticity approaches, using commercial or self-developed Finite Element (FE) codes, with solid, continuum or classical shell elements and different contact models. The material characterization (tensile tests, biaxial tensile tests, monotonic and reverse shear tests, EBSD measurements) and the cup forming steps were performed with care (redundancy of measurements).

Mutation Has No Apparent Effects on Peroxisome Structure or Lipid Metabolism.

Background: Multiple studies of tissue and cell samples from patients and preclinical models of autosomal dominant polycystic kidney disease report abnormal mitochondrial function and morphology and suggest metabolic reprogramming is an intrinsic feature of this disease. Peroxisomes interact with mitochondria physically and functionally, and congenital peroxisome biogenesis disorders can cause various phenotypes, including mitochondrial defects, metabolic abnormalities, and renal cysts. We hypothesized that a peroxisomal defect might contribute to the metabolic and mitochondrial impairments observed in autosomal dominant polycystic kidney disease.

Pathway identification through transcriptome analysis.

Systems-based, agnostic approaches focusing on transcriptomics data have been employed to understand the pathogenesis of polycystic kidney diseases (PKD). While multiple signaling pathways, including Wnt, mTOR and G-protein-coupled receptors, have been implicated in late stages of disease, there were few insights into the transcriptional cascade immediately downstream of Pkd1 inactivation. One of the consistent findings has been transcriptional evidence of dysregulated metabolic and cytoskeleton remodeling pathways.

The pathobiology of polycystic kidney disease from a metabolic viewpoint.

Autosomal dominant polycystic kidney disease (ADPKD) affects an estimated 1 in 1,000 people and slowly progresses to end-stage renal disease (ESRD) in about half of these individuals. Tolvaptan, a vasopressin 2 receptor blocker, has been approved by regulatory authorities in many countries as a therapy to slow cyst growth, but additional treatments that target dysregulated signalling pathways in cystic kidney and liver are needed. Metabolic reprogramming is a prominent feature of cystic cells and a potentially important contributor to the pathophysiology of ADPKD.

A cleavage product of Polycystin-1 is a mitochondrial matrix protein that affects mitochondria morphology and function when heterologously expressed.

Recent studies have reported intrinsic metabolic reprogramming in Pkd1 knock-out cells, implicating dysregulated cellular metabolism in the pathogenesis of polycystic kidney disease. However, the exact nature of the metabolic changes and their underlying cause remains controversial. We show herein that Pkd1 o renal epithelial cells have impaired fatty acid utilization, abnormal mitochondrial morphology and function, and that mitochondria in kidneys of ADPKD patients have morphological alterations.

NEDD4-family E3 ligase dysfunction due to PKHD1/Pkhd1 defects suggests a mechanistic model for ARPKD pathobiology.

Autosomal recessive polycystic kidney disease (ARPKD) is an important childhood nephropathy, occurring 1 in 20,000 live births. The major clinical phenotypes are expressed in the kidney with dilatation of the collecting ducts, systemic hypertension, and progressive renal insufficiency, and in the liver with biliary dysgenesis, portal tract fibrosis, and portal hypertension. The systemic hypertension has been attributed to enhanced distal sodium reabsorption in the kidney, the structural defects have been ascribed to altered cellular morphology, and fibrosis to increased TGF-β signaling in the kidney and biliary tract, respectively.

Fatty Acid Oxidation is Impaired in An Orthologous Mouse Model of Autosomal Dominant Polycystic Kidney Disease.

Background: The major gene mutated in autosomal dominant polycystic kidney disease was first identified over 20 years ago, yet its function remains poorly understood. We have used a systems-based approach to examine the effects of acquired loss of Pkd1 in adult mouse kidney as it transitions from normal to cystic state.

Methods: We performed transcriptional profiling of a large set of male and female kidneys, along with metabolomics and lipidomics analyses of a subset of male kidneys.

Systems biology of polycystic kidney disease: a critical review.

The proliferation and diminishing costs of 'omics' approaches have finally opened the doors for small and medium laboratories to enter the 'systems biology era'. This is a welcome evolution that requires a new framework to design, interpret, and validate studies. Here, we highlight some of the challenges, contributions, and prospects of the 'cyst-ems biology' of polycystic kidney disease.

Cby1 promotes Ahi1 recruitment to a ring-shaped domain at the centriole-cilium interface and facilitates proper cilium formation and function.

Defects in centrosome and cilium function are associated with phenotypically related syndromes called ciliopathies. Cby1, the mammalian orthologue of the Drosophila Chibby protein, localizes to mature centrioles, is important for ciliogenesis in multiciliated airway epithelia in mice, and antagonizes canonical Wnt signaling via direct regulation of β-catenin. We report that deletion of the mouse Cby1 gene results in cystic kidneys, a phenotype common to ciliopathies, and that Cby1 facilitates the formation of primary cilia and ciliary recruitment of the Joubert syndrome protein Arl13b.

Murine Models of Polycystic Kidney Disease.

Polycystic diseases affect approximately 1/1000 and are important causes of kidney failure. No therapies presently are in clinical practice that can prevent disease progression. Multiple mouse models have been produced for the genetic forms of the disease that most commonly affect humans.

Network analysis of a Pkd1-mouse model of autosomal dominant polycystic kidney disease identifies HNF4α as a disease modifier.

Autosomal Dominant Polycystic Kidney Disease (ADPKD; MIM ID's 173900, 601313, 613095) leads to end-stage kidney disease, caused by mutations in PKD1 or PKD2. Inactivation of Pkd1 before or after P13 in mice results in distinct early- or late-onset disease. Using a mouse model of ADPKD carrying floxed Pkd1 alleles and an inducible Cre recombinase, we intensively analyzed the relationship between renal maturation and cyst formation by applying transcriptomics and metabolomics to follow disease progression in a large number of animals induced before P10.

Pkd1 and Pkd2 are required for normal placental development.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is a common cause of inherited renal failure that results from mutations in PKD1 and PKD2. The disorder is characterized by focal cyst formation that involves somatic mutation of the wild type allele in a large fraction of cysts. Consistent with a two-hit mechanism, mice that are homozygous for inactivating mutations of either Pkd1 or Pkd2 develop cystic kidneys, edema and hemorrhage and typically die in midgestation.

Pkd1 haploinsufficiency increases renal damage and induces microcyst formation following ischemia/reperfusion.

Mutations in PKD1 cause the majority of cases of autosomal dominant polycystic kidney disease (ADPKD). Because polycystin 1 modulates cell proliferation, cell differentiation, and apoptosis, its lower biologic activity observed in ADPKD might influence the degree of injury after renal ischemia/reperfusion. We induced renal ischemia/reperfusion in 10- to 12-wk-old male noncystic Pkd1(+/-) and wild-type mice.

Immunohistochemical detection of polyductin and co-localization with liver progenitor cell markers during normal and abnormal development of the intrahepatic biliary system and in adult hepatobiliary carcinomas.

The longest open reading frame of PKHD1 (polycystic kidney and hepatic disease 1), the autosomal recessive polycystic kidney disease (ARPKD) gene, encodes a single-pass, integral membrane protein named polyductin or fibrocystin. A fusion protein comprising its intracellular C-terminus, FP2, was previously used to raise a polyclonal antiserum shown to detect polyductin in several human tissues, including liver. In the current study, we aimed to investigate by immunohistochemistry the detailed polyductin localization pattern in normal (ductal plate [DP], remodelling ductal plate [RDP], remodelled bile ducts) and abnormal development of the primitive intrahepatic biliary system, known as ductal plate malformation (DPM).

Polycystic kidney disease, cilia, and planar polarity.

Cystic kidney diseases are characterized by dilated or cystic kidney tubular segments. Changes in planar cell polarity, flow sensing, and/or proliferation have been proposed to explain these disorders. Over the last few years, several groups have suggested that ciliary dysfunction is a central component of cyst formation.

Biliary and pancreatic dysgenesis in mice harboring a mutation in Pkhd1.

Autosomal recessive polycystic kidney disease is a hereditary fibrocystic disease that involves the kidneys and the biliary tract. Mutations in the PKHD1 gene are responsible for typical forms of autosomal recessive polycystic kidney disease. We have generated a mouse model with targeted mutation of Pkhd1 by disrupting exon 4, resulting in a mutant transcript with deletion of 66 codons and expression at approximately 30% of wild-type levels.

Essential role of cleavage of Polycystin-1 at G protein-coupled receptor proteolytic site for kidney tubular structure.

Polycystin-1 (PC1) has an essential function in renal tubular morphogenesis and disruption of its function causes cystogenesis in human autosomal dominant polycystic kidney disease. We have previously shown that recombinant human PC1 is cis-autoproteolytically cleaved at the G protein-coupled receptor proteolytic site domain. To investigate the role of cleavage in vivo, we generated by gene targeting a Pkd1 knockin mouse (Pkd1(V/V)) that expresses noncleavable PC1.

A critical developmental switch defines the kinetics of kidney cyst formation after loss of Pkd1.

Autosomal dominant polycystic kidney disease is an important cause of end-stage renal disease, for which there is no proven therapy. Mutations in PKD1 (the gene encoding polycystin-1) are the principal cause of this disease. The disease begins in utero and is slowly progressive, but it is not known whether cystogenesis is an ongoing process during adult life.

Genetic interaction studies link autosomal dominant and recessive polycystic kidney disease in a common pathway.

Polycystic kidney disease (PKD) describes a heterogeneous collection of disorders that differ significantly with respect to their etiology and clinical presentation. They share, however, abnormal tubular morphology as a common feature, leading to the hypothesis that their respective gene products may function cooperatively in a common pathway to maintain tubular integrity. To study the pathobiology of one major form of human PKD, we generated a mouse line with a floxed allele of Pkhd1, the orthologue of the gene mutated in human autosomal recessive PKD.

Polyductin undergoes notch-like processing and regulated release from primary cilia.

Mutations at a single locus, PKHD1, are responsible for causing human autosomal recessive polycystic kidney disease (ARPKD). Recent studies suggest that the cystic disease might result from defects in planar cell polarity, but how the 4074 amino acid ciliary protein encoded by the longest open reading frame of this transcriptionally complex gene may regulate this process is unknown. Using novel in vitro expression systems, we show that the PKHD1 gene product polyductin/fibrocystin undergoes a complicated pattern of Notch-like proteolytic processing.

N-acetylcysteine attenuates the progression of chronic renal failure.

Background: Lipid peroxidation impairs renal function. Aldosterone contributes to renal injury in the remnant kidney model. This study aimed to determine the effects of the antioxidant N-acetylcysteine (NAC) on renal function and aldosterone levels in chronic renal failure.