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The multi-gene claudin (CLDN) family of tight junction proteins have isoform-specific roles in blood–tissue barrier regulation. CLDN17, a putative anion pore-forming CLDN based on its structural characterization, is assumed to regulate anion balance across the blood-tissue barriers. However, our knowledge about CLDN17 in physiology and pathology is limited. The current study investigated how Cldn17 deficiency in mice affects blood electrolytes and kidney structure. Cldn17−/− mice revealed no breeding abnormalities, but the newborn pups exhibited delayed growth. Adult Cldn17−/− mice displayed electrolyte imbalance, oxidative stress, and injury to the kidneys. Ingenuity pathway analysis followed by RNA-sequencing revealed hyperactivation of signaling pathways and downregulation of SOD1 expression in kidneys associated with inflammation and reactive oxygen species generation, demonstrating the importance of Cldn17 in the maintenance of electrolytes and reactive oxygen species across the blood-tissue barrier.

The multi-gene claudin (CLDN) family of tight junction proteins have isoform-specific roles in blood–tissue barrier regulation. CLDN17, a putative anion pore-forming CLDN based on its structural characterization, is assumed to regulate anion balance across the blood-tissue barriers. However, our knowledge about CLDN17 in physiology and pathology is limited. The current study investigated how Cldn17 deficiency in mice affects blood electrolytes and kidney structure. Cldn17−/− mice revealed no breeding abnormalities, but the newborn pups exhibited delayed growth. Adult Cldn17−/− mice displayed electrolyte imbalance, oxidative stress, and injury to the kidneys. Ingenuity pathway analysis followed by RNA-sequencing revealed hyperactivation of signaling pathways and downregulation of SOD1 expression in kidneys associated with inflammation and reactive oxygen species generation, demonstrating the importance of Cldn17 in the maintenance of electrolytes and reactive oxygen species across the blood-tissue barrier. [ABSTRACT FROM AUTHOR]

Simple Summary: The molecular mechanisms regulating the switch from the growth of tumor cells to invasive phenotype for metastasis is largely unknown. Molecules such as Akt1 and TGFβ have been demonstrated to play reciprocal roles in the early and advanced stages of cancers, and epithelial-to-mesenchymal transition has been identified as a common link in the process. Advancing our knowledge on the direct association between these two pathways and how their effects are reconciled in the advanced stages of cancers such as prostate cancer will have therapeutic benefits. Identifying the role of microRNAs in the process will also benefit the scientific community. Akt1 suppression in advanced cancers has been indicated to promote metastasis. Our understanding of how Akt1 orchestrates this is incomplete. Using the NanoString®-based miRNA and mRNA profiling of PC3 and DU145 cells, and subsequent data analysis using the DIANA-mirPath, dbEMT, nCounter, and Ingenuity® databases, we identified the miRNAs and associated genes responsible for Akt1-mediated prostate cancer (PCa) epithelial-to-mesenchymal transition (EMT). Akt1 loss in PC3 and DU145 cells primarily induced changes in the miRNAs and mRNAs regulating EMT genes. These include increased miR-199a-5p and decreased let-7a-5p expression associated with increased TGFβ-R1 expression. Treatment with locked nucleic acid (LNA) miR-199a-5p inhibitor and/or let-7a-5p mimic induced expression changes in EMT genes correlating to their anticipated effects on PC3 and DU145 cell motility, invasion, and TGFβ-R1 expression. A correlation between increased miR-199a-5p and TGFβ-R1 expression with reduced let-7a-5p was also observed in high Gleason score PCa patients in the cBioportal database analysis. Collectively, our studies show the effect of Akt1 suppression in advanced PCa on EMT modulating miRNA and mRNA expression changes and highlight the potential benefits of miR-199a-5p and let-7a-5p in therapy and/or early screening of mPCa. [ABSTRACT FROM AUTHOR]