Update and review of adult polycystic kidney disease

Discovery of putative inhibitors of human Pkd1 enzyme: Molecular docking, dynamics and simulation, QSAR, and MM/GBSA

Polycystic kidney disease is the most prevalent hereditary kidney disease globally and is mainly linked to the overexpression of a gene called PKD1. To date, there is no effective treatment available for polycystic kidney disease, and the practicing treatments only provide symptomatic relief. Discovery of the compounds targeting the PKD1 gene by inhibiting its expression under the disease condition could be crucial for effective drug development. In this study, a molecular docking and molecular dynamic simulation, QSAR, and MM/GBSA-based approaches were used to determine the putative inhibitors of the Pkd1 enzyme from a library of 1379 compounds. Initially, fourteen compounds were selected based on their binding affinities with the Pkd1 enzyme using MOE and AutoDock tools. The selected drugs were further investigated to explore their properties as drug candidates and the stability of their complex formation with the Pkd1 enzyme. Based on the physicochemical and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) properties, and toxicity profiling, two compounds including olsalazine and diosmetin were selected for the downstream analysis as they demonstrated the best drug-likeness properties and highest binding affinity with Pkd1 in the docking experiment. Molecular dynamic simulation using Gromacs further confirmed the stability of olsalazine and diosmetin complexes with Pkd1 and establishing interaction through strong bonding with specific residues of protein. High biological activity and binding free energies of two complexes calculated using 3D QSAR and Schrodinger module, respectively further validated our results. Therefore, the molecular docking and dynamics simulation-based in-silico approach used in this study revealed olsalazine and diosmetin as potential drug candidates to combat polycystic kidney disease by targeting Pkd1 enzyme.

Measured and Estimated Glomerular Filtration Rate to Evaluate Rapid Progression and Changes over Time in Autosomal Polycystic Kidney Disease: Potential Impact on Therapeutic Decision-Making

Autosomal polycystic kidney disease (ADPKD) is the most common genetic form of kidney failure, reflecting unmet needs in management. Prescription of the only approved treatment (tolvaptan) is limited to persons with rapidly progressing ADPKD. Rapid progression may be diagnosed by assessing glomerular filtration rate (GFR) decline, usually estimated (eGFR) from equations based on serum creatinine (eGFRcr) or cystatin-C (eGFRcys). We have assessed the concordance between eGFR decline and identification of rapid progression (rapid eGFR loss), and measured GFR (mGFR) declines (rapid mGFR loss) using iohexol clearance in 140 adults with ADPKD with ≥3 mGFR and eGFRcr assessments, of which 97 also had eGFRcys assessments. The agreement between mGFR and eGFR decline was poor: mean concordance correlation coefficients (CCCs) between the method declines were low (0.661, range 0.628 to 0.713), and Bland and Altman limits of agreement between eGFR and mGFR declines were wide. CCC was lower for eGFRcys. From a practical point of view, creatinine-based formulas failed to detect rapid mGFR loss (-3 mL/min/y or faster) in around 37% of the cases. Moreover, formulas falsely indicated around 40% of the cases with moderate or stable decline as rapid progressors. The reliability of formulas in detecting real mGFR decline was lower in the non-rapid-progressors group with respect to that in rapid-progressor patients. The performance of eGFRcys and eGFRcr-cys equations was even worse. In conclusion, eGFR decline may misrepresent mGFR decline in ADPKD in a significant percentage of patients, potentially misclassifying them as progressors or non-progressors and impacting decisions of initiation of tolvaptan therapy.

Investigational agents for autosomal dominant polycystic kidney disease: preclinical and early phase study insights

INTRODUCTION

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common inherited kidney condition caused by a single-gene mutation. It leads patients to kidney failure in more than 50% of cases by the age of 60, and, given the dominant inheritance, this disease is present in the family history in more than 90% of cases.

AREAS COVERED

This review aims to analyze the set of preclinical and early-phase studies to provide a general view of the current progress on ADPKD therapeutic options. Articles from PubMed and the current status of the trials listed in clinicaltrials.gov were examined for the review.

EXPERT OPINION

Many potential therapeutic targets are currently under study for the treatment of ADPKD. A few drugs have reached the clinical phase, while many are currently still in the preclinical phase. Organoids could be a novel approach to the study of drugs in this phase. Other than pharmacological options, very important developing approaches are represented by gene therapy and the use of MiRNA inhibitors.

The screening, diagnosis, and management of patients with autosomal dominant polycystic kidney disease: A national consensus statement from Taiwan

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of end-stage kidney disease (ESKD) worldwide. Guidelines for the diagnosis and management of ADPKD in Taiwan remains unavailable. In this consensus statement, we summarize updated information on clinical features of international and domestic patients with ADPKD, followed by suggestions for optimal diagnosis and care in Taiwan. Specifically, counselling for at-risk minors and reproductive issues can be important, including ethical dilemmas surrounding prenatal diagnosis and pre-implantation genetic diagnosis. Studies reveal that ADPKD typically remains asymptomatic until the fourth decade of life, with symptoms resulting from cystic expansion with visceral compression, or rupture. The diagnosis can be made based on a detailed family history, followed by imaging studies (ultrasound, computed tomography, or magnetic resonance imaging). Genetic testing is reserved for atypical cases mostly. Common tools for prognosis prediction include total kidney volume, Mayo classification and PROPKD/genetic score. Screening and management of complications such as hypertension, proteinuria, urological infections, intracranial aneurysms, are also crucial for improving outcome. We suggest that the optimal management strategies of patients with ADPKD include general medical care, dietary recommendations and ADPKD-specific treatments. Key points include rigorous blood pressure control, dietary sodium restriction and Tolvaptan use, whereas the evidence for somatostatin analogues and mammalian target of rapamycin (mTOR) inhibitors remains limited. In summary, we outline an individualized care plan emphasizing careful monitoring of disease progression and highlight the need for shared decision-making among these patients.

DNAJB11 Mutation in ADPKD Patients: Clinical Characteristics in a Monocentric Cohort

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a late-onset cilia-related disorder, characterized by progressive cystic enlargement of the kidneys. It is genetically heterogeneous with PKD1 and PKD2 pathogenic variants identified in approximately 78% and 15% of families, respectively. More recently, additional ADPKD genes, such as DNAJB11, have been identified and included in the diagnostic routine test for renal cystic diseases. However, despite recent progress in ADPKD molecular approach, approximately ~7% of ADPKD-affected families remain genetically unresolved. We collected a cohort of 4 families from our center, harboring heterozygous variants in the DNAJB11 gene along with clinical and imaging findings consistent with previously reported features in DNAJB11 mutated patients. Mutations were identified as likely pathogenetic (LP) in three families and as variants of uncertain significance (VUS) in the remaining one. One patient underwent to kidney biopsy and showed a prevalence of interstitial fibrosis that could be observed in ~60% of the sample. The presence in the four families from our cohort of ADPKD characteristics together with ADTKD features, such as hyperuricemia, diabetes, and chronic interstitial fibrosis, supports the definition of DNAJB11 phenotype as an overlap disease between these two entities, as originally suggested by the literature.

Pedigree Analysis of Polycystic Kidney Disease Patients: Bangladeshi Perspective

Background

Polycystic kidney disease (PKD), an inheritance disorder which is the fourth leading cause of the end-stage renal disease. The inheritance pattern can be diagnosed and confirmed by pedigree analysis. The aim of the present research was to determine the type and frequency of PKD using pedigree analysis.

Materials and Methods

The present research was designed as a cross-sectional descriptive study. Thirty-eight adult Bangladeshi PKD patients were recruited using a selection checklist from the Department of Nephrology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. Data were collected using a data collection sheet after taking informed written consent. The pedigree was drawn using the genetic pedigree chart creation software f-tree V4.0.6. The percentage frequencies of different types of pedigree were calculated using the Statistical Package for the Social Sciences software, version 23.

Results

A total of 24 (63.20%) had a positive family history and 36.80% (14) had no positive family history. All of the patients with a positive family history had vertical transmission; male and female were equally inheriting the gene. Out of these 24 patients, 4.17% (one), 8.33% (two), and 16.67% (four) had a homozygous/heterozygous state, skip generation, and male to male transmission, respectively.

Conclusions

Pedigree analysis of PKD patients showed an increased value in early diagnosis and better management and prognosis of the disease.

Functions of the primary cilium in the kidney and its connection with renal diseases

The nonmotile primary cilium is a sensory structure found on most mammalian cell types that integrates multiple signaling pathways involved in tissue development and postnatal function. As such, mutations disrupting cilia activities cause a group of disorders referred to as ciliopathies. These disorders exhibit a wide spectrum of phenotypes impacting nearly every tissue. In the kidney, primary cilia dysfunction caused by mutations in polycystin 1 (Pkd1), polycystin 2 (Pkd2), or polycystic kidney and hepatic disease 1 (Pkhd1), result in polycystic kidney disease (PKD), a progressive disorder causing renal functional decline and end-stage renal disease. PKD affects nearly 1 in 1000 individuals and as there is no cure for PKD, patients frequently require dialysis or renal transplantation. Pkd1, Pkd2, and Pkhd1 encode membrane proteins that all localize in the cilium. Pkd1 and Pkd2 function as a nonselective cation channel complex while Pkhd1 protein function remains uncertain. Data indicate that the cilium may act as a mechanosensor to detect fluid movement through renal tubules. Other functions proposed for the cilium and PKD proteins in cyst development involve regulation of cell cycle and oriented division, regulation of renal inflammation and repair processes, maintenance of epithelial cell differentiation, and regulation of mitochondrial structure and metabolism. However, how loss of cilia or cilia function leads to cyst development remains elusive. Studies directed at understanding the roles of Pkd1, Pkd2, and Pkhd1 in the cilium and other locations within the cell will be important for developing therapeutic strategies to slow cyst progression.

An update on treatments for autosomal dominant polycystic kidney disease

ABSTRACT

Autosomal dominant polycystic kidney disease (ADPKD) is less common than primary hypertension or diabetes but should be considered as a possible cause of end-stage renal disease, especially in young patients without comorbidities. Because of ADPKD's nonspecific symptoms, the diagnosis, treatment, and pertinent patient education may be delayed. This article describes ADPKD and its management, including tolvaptan, a new treatment with the potential to reduce or delay morbidity. However, only a subset of patients qualifies for this expensive treatment.

The Cystic Fibrosis Transmembrane Conductance Regulator Gene (CFTR) Is under Post-Transcriptional Control of microRNAs: Analysis of the Effects of agomiRNAs Mimicking miR-145-5p, miR-101-3p, and miR-335-5p

(1) Background: MicroRNAs are involved in the expression of the gene encoding the chloride channel CFTR (Cystic Fibrosis Transmembrane Conductance Regulator); the objective of this short report is to study the effects of the treatment of bronchial epithelial Calu-3 cells with molecules mimicking the activity of pre-miR-145-5p, pre-miR-335-5p, and pre-miR-101-3p, and to discuss possible translational applications of these molecules in pre-clinical studies focusing on the development of protocols of possible interest in therapy; (2) Methods: CFTR mRNA was quantified by Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR). The production of the CFTR protein was assessed by Western blotting; (3) Results: The treatment of Calu-3 cells with agomiR-145-5p caused the highest inhibition of CFTR mRNA accumulation and CFTR production; (4) Conclusions: The treatment of target cells with the agomiR pre-miR-145-5p should be considered when CFTR gene expression should be inhibited in pathological conditions, such as polycystic kidney disease (PKD), some types of cancer, cholera, and SARS-CoV-2 infection.

Review of the Use of Animal Models of Human Polycystic Kidney Disease for the Evaluation of Experimental Therapeutic Modalities

Autosomal dominant polycystic kidney disease, autosomal recessive polycystic kidney disease, and nephronophthisis are hereditary disorders with the occurrence of numerous cysts in both kidneys, often causing chronic and end-stage renal failure. Animal models have played an important role in recent advances in research not only on disease onset and progressive mechanisms but also on the development of therapeutic interventions. For a long time, spontaneous animal models have been used as the primary focus for human diseases; however, after the identification of the nucleotide sequence of the responsible genes, PKD1, PKD2, PKHD1, and NPHPs, various types of genetically modified models were developed by genetic and reproductive engineering techniques and played the leading role in the research field. In this review, we present murine models of hereditary renal cystic diseases, discussing their potential benefits in the development of therapeutic strategies.

The natural history of autosomal dominant polycystic kidney disease. A strategy for grouping families and mutations

Autosomal dominant polycystic kidney disease (ADPKD) is a main cause of end-stage renal disease. Today, knowledge of its genetic basis has made it possible to develop strategies that prevent the transmission of the disease.

OBJECTIVES

The objective of the study was to analyze the natural history of ADPKD in the province of Córdoba and to design a database that allows grouping families with different mutations.

PATIENTS AND METHODS

All patients (n = 678) diagnosed with ADPKD followed by the Córdoba nephrology service are included. Various clinical variables (age and sex), genetic variables (mutation in PKD1, PKD2) and the need for renal replacement therapy (RRT) were retrospectively analyzed.

RESULTS

The prevalence was 61 cases per 100,000 inhabitants. Median renal survival was significantly worse in PKD1 (57.5 years) than in PKD2 (70 years) (log-rank p = 0.000). We have genetically identified 43.8% of the population, detecting PKD1 mutations in 61.2% and PKD2 mutations in 37.4% of cases, respectively. The most frequent mutation, in PKD2 (c.2159del), appeared in 68 patients belonging to 10 different families. The one with the worst renal prognosis was a truncating mutation in PKD1 (c.9893 G > A). These patients required RRT at a median age of 38.7 years.

CONCLUSIONS

Renal survival of ADPKD in the province of Córdoba is similar to that described in the literature. We detected PKD2 mutations in 37.4% of cases. This strategy allows us to know the genetic basis of a large proportion of our population while saving resources. This is essential to be able to offer primary prevention of ADPKD through preimplantation genetic diagnosis.

Routine laboratory testing in hemodialysis: how frequently is it needed?

Background:

Hemodialysis patients are followed by routine laboratory testing. There is uncertainty whether these tests always lead to a change in decision-making. This study aims to discover the number of yearly interventions/changes in prescription based on these tests and depict the group of patients who would benefit from reduced or increased laboratory blood tests.

Methods:

This is a multi-center retrospective study that included patients on hemodialysis for more than one year. Laboratory data collected included yearly average of hemoglobin, urea reduction ratio (URR), serum phosphate, calcium, potassium, parathormone (PTH), ferritin and transferrin saturation (TSAT); changes in prescription of erythropoietin-stimulating agents (ESAs), intravenous (IV) iron, alfacalcidol, phosphate binders and dialysis parameters were retrieved from medical records. A multivariate regression analysis assessed factors associated with high number of interventions.

Results:

A total of 210 hemodialysis patients were included: 62.4% males, 47.1% diabetics. Their median age was 72 (62,78.5) years. Their laboratory parameters were within KDIGO targets. The median number of yearly interventions was 5 (3,7) for ESAs, 4 (2,6) for IV iron, 1 (0,2.25) for phosphate binders, 0 (0,1) for alfacalcidol. Based on the multivariate analysis, patients with higher ferritin, frequent changes in ESA, more changes in alfacalcidol and higher PTH had higher number of prescription’s changes in ESA, IV iron, phosphate binders and alfacalcidol respectively.

Conclusion:

While maintaining KDIGO targets, therapeutic interventions following routine laboratory testing did not exceed six times yearly for all parameters. This suggests that a reduced testing frequency in hemodialysis patients is possible without any impact on quality of care. A personalized approach remains safe for hemodialysis patients while reducing the cost. This is very relevant in low-resource settings and during economic crises and needs to be evaluated in prospective studies.

Predicting the number of citations of polycystic kidney disease with 100 top-cited articles since 2010: Bibliometric analysis

BACKGROUND

Polycystic kidney disease (PKD) is a genetic disorder in which the renal tubules become structurally abnormal, resulting in the development and growth of multiple cysts within the kidneys. Numerous studies on PKD have been published in the literature. However, no such articles used medical subject headings (MeSH terms) to predict the number of article citations. This study aimed to predict the number of article citations using 100 top-cited PKD articles (T100PKDs) and dissect the characteristics of influential authors and affiliated counties since 2010.

METHODS

We searched the PubMed Central® (PMC) database and downloaded 100PKDs from 2010. Citation analysis was performed to compare the dominant countries and authors using social network analysis (SNA). MeSh terms were analyzed by referring to their citations in articles and used to predict the number of article citations using its correlation coefficients (CC) to examine the prediction effect.

RESULTS

We observed that the top 3 countries and journals in 100PKDs were the US (65%), Netherlands (7%), France (5%), J Am Soc Nephrol (21%), Clin J Am Soc Nephrol (8%), and N Engl J Med (6%); the most cited article (PMID = 23121377 with 473 citations) was authored by Vicente Torres from the US in 2012; and the most influential MeSH terms were drug therapy (3087.2), genetics (2997.83), and therapeutic use (2760.7). MeSH terms were evident in the prediction power of the number of article citations (CC = 0.37; t = 3.92; P < .01, n = 100).

CONCLUSIONS

A breakthrough was made by developing a method using MeSH terms to predict the number of article citations based on 100PKDs. MeSH terms are evident in predicting article citations that can be applied to future research, not limited to PKD, as we did in this study.

Management of autosomal dominant polycystic kidney disease in the era of disease-modifying treatment options

Autosomal dominant polycystic kidney disease (ADPKD) is the reported etiology in 10% of end-stage kidney disease (ESKD) patients and has an estimated prevalence of 12.5 million cases worldwide across all ethnicities. There have been major advancements over the last two decades in understanding the pathogenesis and development of disease-modifying treatment options for ADPKD, culminating in regulatory approval of tolvaptan for ADPKD patients at risk of rapid progression to kidney failure. This review highlights the genetic mutations associated with ADPKD, defines patients at risk of rapid progression to ESKD, and focuses on the management of ADPKD in the era of disease-modifying agents.

Spontaneous Polycystic Kidneys with Chronic Renal Failure in an Aged House Musk Shrew (Suncus murinus)

Polycystic kidney disease is one of the most common inheritable renal diseases, characterized by the formation of multiple fluid-filled renal cysts. This disease is a progressive and unfortunately incurable condition. A case of polycystic kidney with chronic renal failure in house musk shrew (Suncus murinus) is described. At clinical presentation, a 16-month-old Suncus murinus showed weight loss and coarse fur. Regarding the biochemical profile, total protein concentrations increased, resulting in a declined albumin: globulin ratio. Blood urea nitrogen and creatinine concentrations were markedly elevated, indicating the end stage of chronic renal failure. Serum amyloid A levels increased and revealed inflammatory reaction during the cyst formation. Histopathologically, multiple cysts were lined by a single layer of epithelial cells or low cuboidal epithelium. The contents were homogenous eosinophilic materials (mucopolysaccharides or mucoproteins) and these cysts contained abundant macrophages. There were also regeneration and dilatation of renal tubes and interstitial fibrosis. The atrophic glomeruli and glomerular capsules were thickened and hyalinized by dense amorphous mucopolysaccharides. These histopathological findings suggested that the pathogenesis of polycystic kidney disease shared a common mechanistic feature across species.

Autosomal Dominant Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease is an inherited multisystemic disorder of the renal tubules with subsequent formation of multiple cysts and enlargement of the kidney, affecting various organs. Diagnosis is initially suspected in those with family history and/or individuals who develop hypertension early on (secondary hypertension) or certain symptoms. Renal function is initially preserved for years secondary to compensatory mechanisms. Associated conditions include: liver cysts, berry aneurysms, kidney stones, etc. The disease course is variable, but patients often progress to end-stage renal failure by age 60. There is no known cure, however, risk factor modification at early stages is critical. Renal transplant is the optimal treatment in ESRD.

Demographic, diagnostic and therapeutic characteristics of autosomal dominant polycystic kidney disease in Ghana

Background

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the commonest of the hereditary kidney diseases and mostly ensues in utero with signs delayed until after several decades. This study assessed the demographic, diagnostic (clinical and biochemical features) and therapeutic patterns among ADPKD patients who attended the nephrology unit of Komfo Anokye Teaching Hospital (KATH) from 2007 to 2018.

Methods

This cross-sectional retrospective analysis of ADPKD patient records was conducted at the nephrology unit of KATH in October 2020. The records of 82 ADPKD was used for this study. Demographic, clinical, biochemical, ultrasonographic and therapeutic data was obtained, organized and analyzed with Statistical Package for the Social Sciences (SPSS).

Results

ADPKD was most prevalent in people within the ages of 31–40 years (25.6 %), with a male (52.4 %) preponderance. The most common clinical features presented were flank pain (30.5 %) and bipedal swelling (18.3 %). Hypertension (42.7 %), urinary tract infections (UTIs) (19.5 %), and anemia (13.4 %) were the most common complications reported. Average level of HDL-c was higher in females (1.7) than in males (1.2) (p = 0.001). Hematuria (34 %) and proteinuria (66 %) were among the biochemical derangements presented. About 81.7 % had CKD at diagnosis with the majority in stages 1 (27.0 %), 3(23.2 %) and 5 (20.3 %). Poor corticomedullary differentiation was observed in 90.2 % of participants and increased echogenicity was observed in 89.0 % of the participants. Estimated GFR (eGFR) correlated positively with echotexture (r = 0.320, p = 0.005) and negatively with CMD (r= -0.303, p = 0.008). About 95.1 % of patients were on conservative therapy including: 73.2 %, 52.4 %, 22.0 %, 13.4 %, 8.5 % on Irebesartan/Lisinopril, Nifecard XL, Hydralazine, Methyldopa and Bisoprolol respectively for hypertension; 26.8 and 3.7 % on Gliclazide and Metformin respectively for Type 2 diabetes mellitus; 25.6 %, 24.4 and 18.3 % on CaCO₃, fersolate and folic acid respectively as nutrient supplements with 4.9 % of participants on renal replacement therapy (RRT).

Conclusions

ADPKD occurs in people aged ≥ 31 years with a higher male preponderance. Clinical features include flank and abdominal pain, bipedal swelling, headache, amongst others. Uremia, hematuria, proteinuria, decreased eGFR, were the common biochemical derangements reported with higher severity detected in men. The therapeutic interventions mostly involved conservative therapy to manage symptoms and other comorbid conditions and rarely renal replacement therapy (RRT).

Application of mesenchymal stem cell-derived exosomes in kidney diseases

Kidney injury (KI) has high morbidity and mortality; there has been no ideal practical treatment available in clinical practice until now. Exosomes are formed from fusing multisubunit body membranes and are secreted into the extracellular matrix, intercellular communication membracusses. As a cell-free treatment, it offers a new approach to the treatment of KI. Exosomes are spherical vesicles with or no separator cup that shapes proteins, and RNA acts on the target cells through various means to promote tissue damage and mitigate apoptosis, both inflammation and oxidative stress. Exosomes derived from mesenchymal stem cells (MSC) have a paracrine function in promoting tissue repair and immune regulation. The MSC-Exos provide specific benefits over the MSCs. The urinary exosomes closely follow the functions and diseases of the kidneys. Though much of the research in this field is only at the preliminary stages, previous research has demonstrated that MSC-Exos damaged tissues to offer proteins, mRNAs, and microRNAs as remedies for kidney injury. Although exosomes' role in tissue repair is currently is greatly debated, several key issues remain unaddressed. This is a summarization of the work done concerning MSC in the treatment of KI.

Autosomal dominant polycystic kidney disease and pioglitazone for its therapy: a comprehensive review with an emphasis on the molecular pathogenesis and pharmacological aspects

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited chronic kidney disorder (CKD) that is characterized by the development of numerous fluid-filled cysts in kidneys. It is caused either due to the mutations in the PKD1 or PKD2 gene that encodes polycystin-1 and polycystin-2, respectively. This condition progresses into end-stage renal disorder if the renal or extra-renal clinical manifestations remain untreated. Several clinical trials with a variety of drugs have failed, and the only Food and Drugs Administration (FDA) approved drug to treat ADPKD to date is tolvaptan that works by antagonizing the vasopressin-2 receptor (V2R). The pathology of ADPKD is complex and involves the malfunction of different signaling pathways like cAMP, Hedgehog, and MAPK/ERK pathway owing to the mutated product that is polycystin-1 or 2. A measured yet substantial number of preclinical studies have found pioglitazone to decrease the cystic burden and improve the renal function in ADPKD. The peroxisome proliferator-activated receptor-gamma is found on the epithelial cells of renal collecting tubule and when it gets agonized by pioglitazone, confers efficacy in ADPKD treatment through multiple mechanisms. There is only one clinical trial (ongoing) wherein it is being assessed for its benefits and risk in patients with ADPKD, and is expected to get approval from the regulatory body owing to its promising therapeutic effects. This article would encompass the updated information on the epidemiology, pathophysiology of ADPKD, different mechanisms of action of pioglitazone in the treatment of ADPKD with preclinical and clinical shreds of evidence, and related safety updates.

Polycystins as components of large multiprotein complexes of polycystin interactors

Naturally occurring mutations in two separate genes, PKD1 and PKD2, are responsible for the vast majority of all cases of autosomal dominant polycystic kidney disease (ADPKD), one of the most common genetic diseases affecting 1 in 1000 Americans. The hallmark of ADPKD is the development of epithelial cysts in the kidney, liver, and pancreas. PKD1 encodes a large plasma membrane protein (PKD1, PC1, or Polycystin-1) with a long extracellular domain and has been speculated to function as an atypical G protein coupled receptor. PKD2 encodes an ion channel of the Transient Receptor Potential superfamily (TRPP2, PKD2, PC2, or Polycystin-2). Despite the identification of these genes more than 20 years ago, the molecular function of their encoded proteins and the mechanism(s) by which mutations in PKD1 and PKD2 cause ADPKD remain elusive. Genetic, biochemical, and functional evidence suggests they form a multiprotein complex present in multiple locations in the cell, including the plasma membrane, endoplasmic reticulum, and the primary cilium. Over the years, numerous interacting proteins have been identified using directed and unbiased approaches, and shown to modulate function, cellular localization, and protein stability and turnover of Polycystins. Delineation of the molecular composition of the Polycystin complex can have a significant impact on understanding their cellular function in health and disease states and on the identification of more specific and effective therapeutic targets.