Neuronal glutathione depletion elevates the Aß42/Aß40 ratio and tau aggregation in Alzheimer's disease mice.

Alzheimer's disease (AD) involves reduced glutathione levels, causing oxidative stress and contributing to neuronal cell death. Our prior research identified diminished glutamate-cysteine ligase catalytic subunit (GCLC) as linked to cell death. However, the effect of GCLC on AD features such as amyloid and tau pathology remained unclear. To address this, we investigated amyloid pathology and tau pathology in mice by combining neuron-specific conditional GCLC knockout mice with amyloid precursor protein (App) knockin (KI) or microtubule-associated protein tau (MAPT) KI mice. Intriguingly, GCLC knockout resulted in an increased Aß42/40 ratio. Additionally, GCLC deficiency in MAPT KI mice accelerated the oligomerization of tau through intermolecular disulfide bonds. These findings suggest that the decline in glutathione levels, due to aging or AD pathology, may contribute to the progression of AD.

Usefulness of preset count acquisition in pediatric 99m Tc-DMSA planar imaging.

OBJECTIVE: This study was aimed at determining the minimum acquisition count to provide diagnosable image quality (DIQ) and investigating the usefulness of preset count acquisition (PCA) for planar images of pediatric 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. METHODS: First, we calculated a coefficient of variation (CV) for DIQ with the shortest acquisition time through visual evaluation in 12 pediatric patients who underwent 99mTc-DMSA scintigraphy. Second, a minimum acquisition count to achieve the CV for DIQ was determined with the single regression analysis using CV as an explanatory variable and the total acquisition count as an objective variable in 81 pediatric patients. Finally, we compared PCA images based on the minimum acquisition count and preset time acquisition (PTA) images for 5 min in terms of the acquisition time, CV, and renal uptake ratio in another 23 pediatric patients. RESULTS: The visual evaluation showed that the CV corresponding to DIQ with the shortest acquisition time was 27.1%. The total acquisition count corresponding to DIQ was revealed to be 299,764 in the single regression analysis and was determined to be 300,000 after rounding. The CV and its standard deviation in PCA at 300,000 counts and PTA for 5 min were 26.4 ± 0.6% and 24.8 ± 1.3%, respectively. The standard deviation of CV in PCA at 300,000 counts was smaller than that in PTA for 5 min, indicating little variation in image quality between cases. The acquisition time in PCA at 300,000 counts (3.1 ± 0.7 min) was shorter than that in PTA for 5 min (5.0 ± 0.0 min). The intraclass correlation coefficient between renal uptake ratios for PCA and PTA was 0.98, indicating an extremely high concordance. CONCLUSIONS: The minimum acquisition count required for the DIQ was 300,000. In addition, PCA at 300,000 counts was demonstrated to be useful by providing stable image quality at the shortest acquisition time.

Involvement of the genus Corynebacterium in the pathogenesis of pigmented intratarsal keratinous cyst.

Intratarsal keratinous cyst (IKC) is a benign cystic lesion of the eyelid that retains keratin flakes. IKCs are usually yellow to white cystic lesions but rarely become brown or gray-blue, making clinical diagnosis difficult. The mechanisms by which dark brown pigments are generated in pigmented IKC are unclear. The authors report a case of pigmented IKC that had melanin pigments within the lining of the cyst wall and within the cyst. Focal infiltrates of lymphocytes were observed in the dermis, particularly beneath the cyst wall in areas with more melanocytes and intense melanin deposition. These pigmented parts faced bacterial colonies inside the cyst, which were identified to be Corynebacterium species in a bacterial flora analysis. The pathogenesis of pigmented IKC in relation to inflammation and bacterial flora is discussed.

Neuronal glutathione loss leads to neurodegeneration involving gasdermin activation.

Accumulating evidence suggests that glutathione loss is closely associated with the progression of neurodegenerative disorders. Here, we found that the neuronal conditional-knockout (KO) of glutamyl-cysteine-ligase catalytic-subunit (GCLC), a rate-limiting enzyme for glutathione synthesis, induced brain atrophy accompanied by neuronal loss and neuroinflammation. GCLC-KO mice showed activation of C1q, which triggers engulfment of neurons by microglia, and disease-associated-microglia (DAM), suggesting that activation of microglia is linked to the neuronal loss. Furthermore, gasdermins, which regulate inflammatory form of cell death, were upregulated in the brains of GCLC-KO mice, suggesting the contribution of pyroptosis to neuronal cell death in these animals. In particular, GSDME-deficiency significantly attenuated the hippocampal atrophy and changed levels of DAM markers in GCLC-KO mice. Finally, we found that the expression of GCLC was decreased around amyloid plaques in AppNL-G-F AD model mice. AppNL-G-F mouse also exhibited inflammatory events similar to GCLC-KO mouse. We propose a mechanism by which a vicious cycle of oxidative stress and neuroinflammation enhances neurodegenerative processes. Furthermore, GCLC-KO mouse will serve as a useful tool to investigate the molecular mechanisms underlying neurodegeneration and in the development of new treatment strategies to address neurodegenerative diseases.

Two cases of nivolumab plus ipilimumab therapy for dialysis patients with advanced bone metastasis from renal cell carcinoma.

Nivolumab and ipilimumab are immune checkpoint inhibitors. Combination therapy with these two drugs has been shown to improve the outcome of advanced renal cell carcinoma. However, data about the safety and the efficacy of combination therapy with these two drugs in hemodialysis patients are small. A 59-year-old male hemodialysis patient presented with bone metastasis from renal cell carcinoma, which was located at the right femur. He received nivolumab plus ipilimumab therapy. At 7 months after treatment, he was diagnosed with diabetes as an immune-related adverse event. He was managed with insulin therapy. At 11 months after treatment, CT revealed cytoreduction of metastasis. A 74-year-old male hemodialysis patient presented with bone metastasis of renal cell carcinoma located at the sacrum and left scapula. He received nivolumab plus ipilimumab therapy. At 6 months after treatment, CT showed no progression of metastasis. Nivolumab and ipilimumab therapy might be a viable treatment for hemodialysis patients with bone metastasis from renal cell carcinoma. However, close attention should be paid immune-related adverse events in such patients.

An isogenic panel of App knock-in mouse models: Profiling ß-secretase inhibition and endosomal abnormalities.

We previously developed single App knock-in mouse models of Alzheimer's disease (AD) that harbor the Swedish and Beyreuther/Iberian mutations with or without the Arctic mutation (AppNL-G-F and AppNL-F mice). We have now generated App knock-in mice devoid of the Swedish mutations (AppG-F mice) and evaluated its characteristics. Amyloid ß peptide (Aß) pathology was exhibited by AppG-F mice from 6 to 8 months of age and was accompanied by neuroinflammation. Aß-secretase inhibitor, verubecestat, attenuated Aß production in AppG-F mice, but not in AppNL-G-F mice, indicating that the AppG-F mice are more suitable for preclinical studies of ß-secretase inhibition given that most patients with AD do not carry the Swedish mutations. Comparison of isogenic App knock-in lines revealed that multiple factors, including elevated C-terminal fragment ß (CTF-ß) and humanization of Aß might influence endosomal alterations in vivo. Thus, experimental comparisons between different isogenic App, knock-in mouse lines will provide previously unidentified insights into our understanding of the etiology of AD.

Somatostatin-evoked Aß catabolism in the brain: Mechanistic involvement of α-endosulfine-KATP channel pathway.

Alzheimer's disease (AD) is characterized by the deposition of amyloid ß peptide (Aß) in the brain. The neuropeptide somatostatin (SST) regulates Aß catabolism by enhancing neprilysin (NEP)-catalyzed proteolytic degradation. However, the mechanism by which SST regulates NEP activity remains unclear. Here, we identified α-endosulfine (ENSA), an endogenous ligand of the ATP-sensitive potassium (KATP) channel, as a negative regulator of NEP downstream of SST signaling. The expression of ENSA is significantly increased in AD mouse models and in patients with AD. In addition, NEP directly contributes to the degradation of ENSA, suggesting a substrate-dependent feedback loop regulating NEP activity. We also discovered the specific KATP channel subtype that modulates NEP activity, resulting in the Aß levels altered in the brain. Pharmacological intervention targeting the particular KATP channel attenuated Aß deposition, with impaired memory function rescued via the NEP activation in our AD mouse model. Our findings provide a mechanism explaining the molecular link between KATP channel and NEP activation, and give new insights into alternative strategies to prevent AD.

Significance of IL36RN mutation analyses in the management of impetigo herpetiformis: A case report and review of published cases.

Impetigo herpetiformis (IH) is a rare variant of generalized pustular psoriasis (GPP), which develops during pregnancy. GPP is associated with mutations of IL36RN, but it is still unclear whether the same is true of IH. A 20-year-old Japanese woman developed erythema and pustules on her trunk during the 27th week of her first pregnancy. Within 1 month, the skin lesions spread over her whole body, accompanied by fever. Skin biopsy revealed Kogoj's spongiform pustules in the epidermis and she was diagnosed with IH. Systemic administration of prednisolone failed to resolve the skin eruption, but it was partially improved by the addition of cyclosporin. The patient gave birth to a healthy female infant. After delivery, her erythema relapsed and the effect of granulocyte and monocyte adsorption apheresis was limited. Thus, secukinumab was administrated, and since then, she has maintained complete remission. Mutation analysis revealed a homozygous c.28C>T (p.Arg10X) mutation in IL36RN. Twelve cases of IH, including that presented here, have been reported together with the results of IL36RN genetic analyses, and 10 of the 12 cases occurred in East Asia (Japan and China) despite the fact that IL36RN mutations in GPP have been reported worldwide. Among 10 IH patients of East Asian descent, seven had IL36RN mutations, all of which were founder mutations causing GPP in East Asia: c.28C>T (p.Arg10X) or c.115+6T>C (p.Arg10ArgfsX1). Thus, East Asian founder mutations may play an important role in the pathogenesis of IH. IH patients with IL36RN mutations have a tendency to require biologics to resolve postpartum flare-ups or sustained psoriatic skin lesions. Because IL36RN mutation status may help predict postpartum flare-ups in IH patients, mutation analysis should be considered to enable preparation for biologic therapy of intractable flare-ups.

Vestibular and cochlear nerve enhancement on MRI and its correlation with vestibulocochlear functional deficits in patients with Ramsay Hunt syndrome.

OBJECTIVE: The correlation between enhancement of the vestibulocochlear nerves on gadolinium-enhanced magnetic resonance imaging (MRI) and vestibulocochlear functional deficits was examined in patients with Ramsay Hunt syndrome (RHS). METHODS: Nineteen patients with RHS who showed herpes zoster oticus, peripheral facial palsy, and vertigo were enrolled. Canal paresis (CP) in the caloric test, abnormal response to ocular and cervical vestibular myogenic potentials (oVEMP and cVEMP), and refractory sensorineural hearing loss were evaluated. MRI images perpendicular to the internal auditory canal were reconstructed to identify the superior (SVN) and inferior vestibular nerves (IVN) and the cochlear nerve (CV). The signal intensity increase (SIinc) of the four-nerve enhancement was calculated as an index. RESULTS: Among RHS patients, 79%, 53%, 17% and 26% showed CP in the caloric test, abnormal responses to oVEMP and cVEMP, and refractory sensorineural hearing loss, respectively. SIinc rates of the SVN were significantly increased in RHS patients with CP in the caloric test, and with abnormal responses to oVEMP and cVEMP. SIinc rates of the SVN tended to increase in RHS patients with refractory sensorineural hearing loss (p = 0.052). SIinc rates of the IVN were significantly increased in RHS patients with abnormal responses to oVEMP and cVEMP, and refractory sensorineural hearing loss, but not in those with CP in the caloric test. SIinc rates of the CN were significantly increased in RHS patients with CP in the caloric test, abnormal response to oVEMP and refractory sensorineural hearing loss, but not in those with abnormal response to cVEMP. CONCLUSION: In patients with RHS, the origin of vertigo may be superior vestibular neuritis, which is affected by reactive varicella-zoster virus from the geniculate ganglion of the facial nerve through the faciovestibular anastomosis. The results also suggested that in some RHS patients, inferior vestibular neuritis contributes to the development of vertigo and that the origin of refractory sensorineural hearing loss is cochlear neuritis.

Electroneurography cannot predict when facial synkinesis develops in patients with facial palsy.

The objective of this study is to clarify when facial palsy patients with lower value of Electroneurography (ENoG) should begin the rehabilitation to prevent the development of facial synkinesis. For this purpose, we examined the relationship between the value of ENoG measured 10-14 days after facial palsy onset and the onset day of the development of oral-ocular synkinesis. Sixteen patients with facial palsy including 11 with Bell's palsy and 5 with Ramsay Hunt syndrome (7 men and 9 women ; 15-73 years old ; mean age, 41.6 years) were enrolled in this study. There was no correlation between ENoG value and the onset day of the development of oral-ocular synkinesis (ρ = .09, p = .73). Oral-ocular synkinesis began to develop in 4.0 ±â€…0.7 months (mean ±â€…SD ; range : 3.1-5.0 months) after facial palsy onset regardless of ENoG value. In conclusion, ENoG value cannot predict when facial synkinesis develops in patients with facial palsy. We recommend that facial palsy patients with a high risk for the development of synkinesis begin the biofeedback rehabilitation with mirror to prevent the development of facial synkinesis 3 months after facial palsy onset. J. Med. Invest. 67 : 87-89, February, 2020.

A transgenic mouse expressing miR-210 in proximal tubule cells shows mitochondrial alteration: possible association of miR-210 with a shift in energy metabolism.

Previously we reported that the microRNA miR-210 is aberrantly upregulated in clear cell renal cell carcinoma (ccRCC) via deregulation of the VHL-HIF pathway. In the present study, to investigate the biological impact of miR-210 in ccRCC tumorigenesis, we developed a transgenic mouse line expressing miR-210 in proximal tubule cells under control of the mouse SGLT2/Slc5a2 promoter. Light microscopy revealed desquamation of the tubule cells and regeneration of the proximal tubule, suggesting that miR-210 expression led to damage of the proximal tubule cells. Electron microscopy revealed alterations to the mitochondria in proximal tubule cells, with marked reduction of the mitochondrial inner membrane, which is the main site of ATP production via oxidative phosphorylation (OxPhos). An additional in vitro study revealed that this loss of the inner membrane was associated with downregulation of Iscu and Ndufa4, the target genes of miR-210, suggesting that the miR-210-ISCU/NDUFA4 axis may affect mitochondrial energy metabolism. Furthermore, metabolome analysis revealed activation of anaerobic glycolysis in miR-210-transfected cells, and consistent with this the secretion of lactate, the final metabolite of anaerobic glycolysis, was significantly increased. Lactate concentration was higher in the kidney cortex of transgenic mice relative to wild-type mice, although the difference was not significant (p = 0.070). On the basis of these findings, we propose that miR-210 may induce a shift of energy metabolism from OxPhos to glycolysis by acting on the mitochondrial inner membrane. In addition to activation of glycolysis, we observed activation of the pentose phosphate pathway (PPP) and an increase in the total amount of amino acids in miR-210-transfected cells. This may help cells synthesize nucleotides and proteins for building new cells. These results suggest that miR-210 may be involved in the metabolic changes in the early stage of ccRCC development, helping the cancer cells to acquire growth and survival advantages. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Epidural analgesia for the treatment of colic attack with retrocaval ureter in late pregnancy complicated with marginal placenta previa: a case report.

BACKGROUND: Retrocaval ureter was diagnosed in a woman complaining of ureteric pain in the last trimester of pregnancy. We describe the rationale behind the administration of epidural analgesia for her colic attack. CASE PRESENTATION: A 41-year-old pregnant woman was hospitalized with a diagnosis of a marginal placenta previa at 34 weeks and 5 days of pregnancy. Her right ureter encircled the dorsal aspect of the inferior vena cava (IVC) and was compressed by a growing fetus, causing hydronephrosis. Her right lower back pain was exacerbated every day, till an epidural catheter was inserted. Her estimated glomerular filtration rate (eGFR) and hematocrit worsened, and an elective cesarean section was performed. CONCLUSION: Epidural analgesia only provided pain relief for a few days. When a pregnant woman presents with a retrocaval ureter and severe pain, short-term epidural analgesia should be considered after evaluating the complex medical condition and size of the fetus.

Generation of App knock-in mice reveals deletion mutations protective against Alzheimer's disease-like pathology.

Although, a number of pathogenic mutations have been found for Alzheimer's disease (AD), only one protective mutation has been identified so far in humans. Here we identify possible protective deletion mutations in the 3'-UTR of the amyloid precursor protein (App) gene in mice. We use an App knock-in mouse model carrying a humanized Aß sequence and three AD mutations in the endogenous App gene. Genome editing of the model zygotes using multiple combinations of CRISPR/Cas9 tools produces genetically mosaic animals with various App 3'-UTR deletions. Depending on the editing efficiency, the 3'-UTR disruption mitigates the Aß pathology development through transcriptional and translational regulation of APP expression. Notably, an App knock-in mouse with a 34-bp deletion in a 52-bp regulatory element adjacent to the stop codon shows a substantial reduction in Aß pathology. Further functional characterization of the identified element should provide deeper understanding of the pathogenic mechanisms of AD.

Electroneurography in the acute stage of facial palsy as a predictive factor for the development of facial synkinesis sequela.

OBJECTIVE: We investigated whether the value of ENoG is a predictive factor for the development of facial synkinesis in patients with facial palsy. METHODS: The degree of oral-ocular synkinesis was evaluated quantitatively by an asymmetry of the interpalpebral space width during the mouth movement (% eye opening). Twenty healthy volunteers without a history of facial palsy (12 men and 8 women; 25-65 years old; mean age: 42.3±9.7years) were included in the study to examine the normal range of % eye opening. Fifty-one patients with facial palsy including 38 with Bell palsy and 15 with herpes zoster oticus (28 men and 25 women; 11-86 years old; mean age: 54±19years) were enrolled to examine the relationship between the ENoG value 10-14days after the onset of facial palsy, and the % eye opening 12 months later. Receiver operating characteristic (ROC) curve for the ENoG value was then used to decide the optimum cut-off value as a predictor of the development of oral-ocular synkinesis. RESULTS: We defined a % eye opening inferior to 85% as an index of the development of oral-ocular synkinesis. There was a significant correlation between the values of ENoG 10-14days after the onset of facial palsy and those of % eye opening 12 months later (ρ=0.81, p<0.001). The area under the ROC curve for the ENoG value was the predictor for the development of oral-ocular synkinesis at 0.913 (95%CI: 0.831-0.996, p<0.001). The optimum cut-off value of ENoG 10-14days after the onset of facial palsy was 46.5% to predict the development of oral-ocular synkinesis 12 months after the onset of facial palsy (sensitivity 97.1% and specificity 77.5%). CONCLUSION: The value of ENoG 10-14days after the onset of facial palsy is a predictive factor for the development of facial synkinesis 12 months later. Since facial palsy patients with a ENoG value inferior to 46.5% have a high risk of developing synkinesis, they should receive the facial biofeedback rehabilitation with a mirror as a preventive therapy.

Distinct functional consequences of ECEL1/DINE missense mutations in the pathogenesis of congenital contracture disorders.

Endothelin-converting enzyme-like 1 (ECEL1, also termed DINE in rodents), a membrane-bound metalloprotease, has been identified as a gene responsible for distal arthrogryposis (DA). ECEL1-mutated DA is generally characterized by ocular phenotypes in addition to the congenital limb contractures that are common to all DA subtypes. Until now, the consequences of the identified pathogenic mutations have remained incompletely understood because of a lack of detailed phenotypic analyses in relevant mouse models. In this study, we generated a new knock-in mouse strain that carries an ECEL1/DINE pathogenic G607S missense mutation, based on a previous study reporting atypical DA hindlimb phenotypes in two siblings with the mutation. We compared the morphological phenotypes of G607S knock-in mice with C760R knock-in mice that we previously established. Both C760R and G607S knock-in mouse embryos showed similar axonal arborization defects with normal trajectory patterns from the spinal cord to the target hindlimb muscles, as well as axon guidance defects of the abducens nerves. Intriguingly, distinct phenotypes in DINE protein localization and mRNA expression were identified in these knock-in mouse lines. For G607S, DINE mRNA and protein expression was decreased or almost absent in motor neurons. In the C760R mutant mice DINE was expressed and localized in the somata of motor neurons but not in axons. Our mutant mouse data suggest that ECEL1/DINE G607S and C760R mutations both lead to motor innervation defects as primary causes in ECEL1-mutated congenital contracture disorders. However, the functional consequences of the two mutations are distinct, with loss of axonal transport of ECEL1/DINE in C760R mutants and mRNA expression deficits in G607S mutants.

Transcriptome analyses demonstrate that Peroxisome Proliferator-Activated Receptor α (PPARα) activity of an ultraviolet absorber, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, as possible mechanism of their toxicity and the gender differences.

2-(2'-Hydroxy-3',5'-di-tert-butylphenyl)benzotriazole (HDBB), the Benzotriazole UV-stabilizer (BUVSs) known as UV-320, is widely used in plastic materials for protection against UV-irradiation. Previously, we reported that oral ingestion of HDBB induce hepatotoxicity including hepatocyte hypertrophy and necrosis in rats and, males was more susceptible compared with females in young rats while no sex-related difference was observed in preweaning rats. Phenotypes observed in our previous study imply involvement of peroxisome proliferator-activated receptor (PPAR) α in HDBB hepatotoxicity, however, direct evidence that HDBB can activate PPARα has not been provided and the mechanism which underlying the gender difference of HDBB hepatotoxicity was not clearly elucidated. Here, we conduct transcriptome analysis using microarray expression profiles in the livers of rats administered HDBB. PPARα agonist activity of HDBB was elucidated by comparison with gene expression data of typical PPARα agonist, i.e. clofibrate, WY-14643, gemfibrozil, and fenofibrate, from TG GATEs database. Moreover, we analyzed for PPARα mRNA expression in the liver of developing male and female rats. PPARα mRNA expression level was higher in males than in females on postnatal days (PNDs) 28 and 35, whereas no sex-related difference was found on PNDs 7 and 22. These results suggest that HDBB exerts its hepatotoxicity through the PPARα signal pathway and the sex-related difference in PPARα expression may contribute to the sex-related difference in susceptibility to hepatotoxicity.

Kidney-specific knockout of Sav1 in the mouse promotes hyperproliferation of renal tubular epithelium through suppression of the Hippo pathway.

We have previously reported that Salvador homologue 1 (SAV1), a component of the Hippo pathway, is significantly down-regulated in high-grade clear cell renal cell carcinoma (ccRCC) due to 14q copy number loss, and that this down-regulation contributes to the proliferation and survival of renal tubular epithelial cells through activation of Yes-associated protein 1 (YAP1), a downstream target of the Hippo pathway. However, the impact of SAV1 loss on the proliferation and survival of kidney cells in vivo remained to be determined. To address this issue, we generated kidney-specific Sav1-knockout (Cdh16-Cre;Sav1(fl/fl) ) mice. Sav1 deficiency enhanced the proliferation of renal tubular epithelial cells in Cdh16-Cre;Sav1(fl/fl) mice, accompanied by nuclear localization of Yap1, suggesting suppression of the Hippo pathway. Sav1 deficiency in renal tubules also caused structural and cellular abnormalities of the epithelial cells, including significant enlargement of their nuclei. Furthermore, Cdh16-Cre;Sav1(fl/fl) mice developed both glomerular and tubular cysts. Although lining cells of the glomerular cysts showed no atypia, those of the tubular cysts showed variations in cell size and nuclear shape, which became more severe as the mice aged. In aged Cdh16-Cre;Sav1(fl/fl) mice, we observed focal disruption of proximal tubules and perivascular lymphocytic infiltration. In conclusion, Sav1 is required for the maintenance of growth, nuclear size and structure of renal tubules under physiological conditions, and its deficiency leads to the acquisition of enhanced proliferation of renal epithelial cells through suppression of Hippo signalling.

Downregulation of WDR20 due to loss of 14q is involved in the malignant transformation of clear cell renal cell carcinoma.

Previously, we reported that genomic loss of 14q occurs more frequently in high-grade than in low-grade clear cell renal cell carcinomas (ccRCCs), and has a significant impact on the levels of expression of genes located in this region, suggesting that such genes may be involved in the malignant transformation of ccRCCs. Here, we found that six of the genes located in the minimal common region of 14q loss were significantly downregulated in high-grade ccRCCs due to copy number loss. Using a dataset from The Cancer Genome Atlas Research Network, we found that downregulation of one of these six genes, WDR20, was significantly associated with poorer outcome in patients with ccRCC, suggesting that WDR20 downregulation may be involved in the malignant transformation of ccRCCs. In functional assays, exogenous WDR20 significantly inhibited the growth of RCC cell lines and induced apoptosis. Interestingly, the phosphorylation levels of ERK and protein kinase B/AKT, which reportedly contribute to the malignant phenotype of RCC cells, were clearly reduced by exogenous expression of WDR20. Thus, our data suggest that downregulation of WDR20 due to 14q loss may be involved in the malignant transformation of ccRCCs, in part through activation of the ERK and protein kinase B/AKT pathways.