Casein kinase 1ε and 1α as novel players in polycystic kidney disease and mechanistic targets for (R)-roscovitine and (S)-CR8

Discovery and Optimization of Highly Selective Inhibitors of CDK5

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent monogenic human disease, but to date, only one therapy (tolvaptan) is approved to treat kidney cysts in ADPKD patients. Cyclin-dependent kinase 5 (CDK5), an atypical member of the cyclin-dependent kinase family, has been implicated as a target for treating ADPKD. However, no compounds have been disclosed to date that selectively inhibit CDK5 while sparing the broader CDK family members. Herein, we report the discovery of CDK5 inhibitors, including GFB-12811, that are highly selective over the other tested kinases. In cellular assays, our compounds demonstrate CDK5 target engagement while avoiding anti-proliferative effects associated with inhibiting other CDKs. In addition, we show that the compounds in this series exhibit promising in vivo PK profiles, enabling their use as tool compounds for interrogating the role of CDK5 in ADPKD and other diseases.

Renal Ciliopathies: Sorting Out Therapeutic Approaches for Nephronophthisis

Nephronophthisis (NPH) is an autosomal recessive ciliopathy and a major cause of end-stage renal disease in children. The main forms, juvenile and adult NPH, are characterized by tubulointerstitial fibrosis whereas the infantile form is more severe and characterized by cysts. NPH is caused by mutations in over 20 different genes, most of which encode components of the primary cilium, an organelle in which important cellular signaling pathways converge. Ciliary signal transduction plays a critical role in kidney development and tissue homeostasis, and disruption of ciliary signaling has been associated with cyst formation, epithelial cell dedifferentiation and kidney function decline. Drugs have been identified that target specific signaling pathways (for example cAMP/PKA, Hedgehog, and mTOR pathways) and rescue NPH phenotypes in in vitro and/or in vivo models. Despite identification of numerous candidate drugs in rodent models, there has been a lack of clinical trials and there is currently no therapy that halts disease progression in NPH patients. This review covers the most important findings of therapeutic approaches in NPH model systems to date, including hypothesis-driven therapies and untargeted drug screens, approached from the pathophysiology of NPH. Importantly, most animal models used in these studies represent the cystic infantile form of NPH, which is less prevalent than the juvenile form. It appears therefore important to develop new models relevant for juvenile/adult NPH. Alternative non-orthologous animal models and developments in patient-based in vitro model systems are discussed, as well as future directions in personalized therapy for NPH.

Applications of Herbal Medicine to Treat Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is a common hereditary kidney disease, which is featured by progressively enlarged bilateral fluid-filled cysts. Enlarging cysts destroy the structure of nephrons, ultimately resulting in the loss of renal function. Eventually, ADPKD develops into end-stage renal disease (ESRD). Currently, there is no effective drug therapy that can be safely used clinically. Patients progressed into ESRD usually require hemodialysis and kidney transplant, which is a heavy burden on both patients and society. Therefore, looking for effective therapeutic drugs is important for treating ADPKD. In previous studies, herbal medicines showed their great effects in multiple diseases, such as cancer, diabetes and mental disorders, which also might play a role in ADPKD treatment. Currently, several studies have reported that the compounds from herbal medicines, such as triptolide, curcumin, ginkolide B, steviol, G. lucidum triterpenoids, Celastrol, saikosaponin-d, Sparganum stoloniferum Buch.-Ham and Cordyceps sinensis, contribute to the inhibition of the development of renal cysts and the progression of ADPKD, which function by similar or different mechanisms. These studies suggest that herbal medicines could be a promising type of drugs and can provide new inspiration for clinical therapeutic strategy for ADPKD. This review summarizes the pharmacological effects of the herbal medicines on ADPKD progression and their underlying mechanisms in both in vivo and in vitro ADPKD models.

Clinical Features of 167 Inpatients with Autosomal Dominant Polycystic Kidney Disease at a Single Center in China

BACKGROUND The aim of this study was to describe the clinical characteristics of Chinese ADPKD inpatients and to identify the factors associated with disease severity. MATERIAL AND METHODS We included 167 hospitalized patients (inpatients) with ADPKD in this study. Multiple regression analyses were conducted to determine factors correlated with estimated glomerular filtration rate (eGFR). Patients were stratified into subgroups according to the presence of symptoms, in which clinical parameters were analyzed and compared. RESULTS The mean age of hospitalized ADPKD patients was 48.7 years old, lumbar and/or abdominal pain was seen in 40.12% of patients, following by nephrolithiasis (38.92%), hematuria (30.54%), and urinary tract infection (24.55%). Serum thrombocyte level and hemoglobin exhibited significant positive correlations with eGFR. Symptomatic patients accounted for 71.26% of the studied population. Patients with hypertension had increased risk of presence of symptoms (OR=2.794, 95%CI=1.341-5.822). Low thrombocyte and hemoglobin levels were observed in patients with hematuria. CONCLUSIONS Thrombocyte level was positively correlated with eGFR but was not associated with presence of PKD-related symptoms, suggesting thrombocyte level might be an independent serum biomarker for disease progression. Hypertension was associated with increased risk of symptom occurrence, indicating the relationship between hypertension and disease progression. This study reveals the clinical characteristics of inpatients with ADPKD in China and provides clinicians with useful insights into this intractable disease.