Biology subjects

Nakanoh, H.

Publications and source records attributed to Nakanoh, H..

2 recordsLinked to original sources

bioRxiv2025

Claudin-1 Inhibitor PDS-0330 Ameliorates Diabetic Kidney Disease by Suppressing Src/Akt/mTOR Signaling Pathway in Podocytes

IntroductionRecent studies have reported that claudin-1, which is reactively expressed in malignant tumors and inflammatory diseases, plays an important role in disease progression. In diabetic kidney disease (DKD), upregulated expression of claudin-1 in podocytes has also been shown to contribute to disease progression. However, it remains unclear whether claudin-1 itself could be a therapeutic target in DKD. In this study, we investigated whether the claudin-1 inhibitor PDS-0330 could ameliorate DKD. MethodsFive-week-old male C57BL/6J mice were fed either a high-fat diet (HFD) or a normal diet (ND). At 15 weeks of age, PDS-0330 (Inh) or vehicle as control (Ctrl) was administered orally once per week for 4 weeks. At the end of the treatment period, blood, urine, and kidney samples were collected. In in vitro study, immortalized podocytes were treated with Inh or Ctrl and cultured for 48 hours in either normal glucose medium (5.5 mM; NG) or high glucose medium (25 mM; HG), after which proteins were extracted for analysis. ResultsMice fed an HFD showed significant increases in body weight and serum glucose levels compared with ND mice, and these parameters were not significantly affected by Inh treatment. HFD mice treated with Ctrl (HFD-Ctrl) exhibited significantly higher urinary albumin excretion than ND mice treated with Ctrl (ND-Ctrl), whereas the Inh-treated HFD mice (HFD-Inh) showed a significant reduction. Transmission electron microscopy revealed foot process effacement in HFD-Ctrl podocytes, which was markedly improved in HFD-Inh mice. Immunofluorescence staining demonstrated claudin-1 expression in podocytes of HFD mice. Furthermore, phospho-mTOR staining in podocytes was significantly increased in HFD-Ctrl compared with ND-Ctrl and was significantly attenuated in HFD-Inh. Western blot analysis of kidney samples revealed activation of the Src/Akt/mTOR signaling pathway in HFD-Ctrl mice, which was significantly reduced in HFD-Inh mice. In in vitro study, Ctrl-treated podocytes cultured in HG (HG-Ctrl) showed significant activation of Src/Akt/mTOR signaling compared with those in NG (NG-Ctrl). This activation was significantly suppressed in Inh-treated podocytes (HG-Inh). ConclusionThese findings suggest that podocyte claudin-1 could be a potential therapeutic target in DKD.

physiology↗

bioRxiv2025

Development and Validation of a Stem Cell-Based Kidney Organoid Platform for Nephrotoxicity Assessment

Background and hypothesisRecent cases of acute kidney injury (AKI) in Japan have been linked to the Beni-koji CholesteHelp supplement. Renal biopsies from affected patients revealed tubular damage, and puberulic acid was subsequently identified as a potential nephrotoxic contaminant. Recognizing the urgent need for a reliable in vitro nephrotoxicity testing platform, we hypothesized that a kidney organoid-based system could replicate nephrotoxic injury and help identify novel nephrotoxicants. In this study, we developed a screening model using kidney organoids derived from adult rat kidney stem (KS) cells and applied it to evaluate the toxicity of puberulic acid. MethodsKidney organoids were generated from KS cells and exposed to established nephrotoxicants, including cisplatin and gentamicin, to validate the model. The nephrotoxicity of puberulic acid was evaluated using both KS cell-derived organoids and wild-type mice. Nephrotoxicity was assessed by morphological changes, Kim-1 mRNA expression, transmission electron microscopy (TEM), and analysis of markers related to mitochondrial injury, oxidative stress, and apoptosis. ResultsThe kidney organoids reproduced morphological features of injury induced by known nephrotoxins and showed significant upregulation of Kim-1 mRNA. Puberulic acid-treated organoids displayed ultrastructural features consistent with acute tubular necrosis (ATN) and increased Kim-1 expression. In vivo, puberulic acid-exposed mice exhibited impaired renal function and histological findings consistent with ATN. Both in vitro and in vivo models revealed mitochondrial structural abnormalities and reduced expression of cytochrome c oxidase subunit IV (COX-IV). Additionally, oxidative stress and apoptotic markers, including 8-hydroxy-2-deoxyguanosine (8-OHdG) and cleaved caspase-3, were significantly elevated, suggesting that puberulic acid induces mitochondrial dysfunction and oxidative stress, leading to tubular cell death. ConclusionPuberulic acid-induced nephrotoxicity was demonstrated using our kidney organoid model. KS cell-derived kidney organoids provide a simple, reproducible, and rapid platform for nephrotoxicity assessment, which contribute to a reduction of animal use in toxicology research.

pharmacology and toxicology↗