TrkC Is Essential for Nephron Function and Trans-Activates Igf1R Signaling

Klotho inhibits IGF1R/PI3K/AKT signalling pathway and protects the heart from oxidative stress during ischemia/reperfusion injury

Ischemia/reperfusion injury (IRI) of the heart involves the activation of oxidative and proapoptotic pathways. Simultaneously Klotho protein presents anti-aging, antiapoptotic and antioxidative properties. Therefore, this study aimed to evaluate the effect of Klotho protein on oxidative stress in hearts subjected to IRI. Isolated rat hearts perfused with the Langendorff method were subjected to ischemia, followed by reperfusion, in the presence or absence of recombinant rat Klotho protein. The factors involved in the activation of insulin-like growth factor receptor (IGF1R)/phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) signalling pathway were evaluated. IRI caused activation of the IGF1R (p = 0.0122)/PI3K (p = 0.0022) signalling, as compared to the aerobic control group. Infusion supply of Klotho protein during IRI significantly reduced the level of phospho-IGF1R (p = 0.0436), PI3K (p = 0.0218) and phospho-AKT (p = 0.0020). Transcriptional activity of forkhead box protein O3 (FOXO3) was reduced (p = 0.0207) in hearts subjected to IRI, compared to aerobic control. Administration of Klotho decreased phosphorylation of FOXO3 (p = 0.0355), and enhanced activity of glutathione peroxidase (p = 0.0452) and superoxide dismutase (p = 0.0060) in IRI + Klotho group. The levels of reactive oxygen/nitrogen species (ROS/RNS) (p = 0.0480) and hydrogen peroxide (H2O2) (p = 0.0460), and heart injury (p = 0.0005) were significantly increased in hearts from the IRI group in comparison to the aerobic group. Klotho reduced NADPH oxidase 2 (NOX2) (p = 0.0390), ROS/RNS (p = 0.0435) and H2O2 (p = 0.0392) levels, and heart damage (p = 0.0286) in the hearts subjected to IRI. In conclusion, Klotho contributed to the protection of the heart against IRI and oxidative stress via inhibition of the IGF1R/PI3K/AKT pathway, thus can be recognized as a novel cardiopreventive/cardioprotective agent.

Analysis of the Expression of Neurotrophins and Their Receptors in Adult Zebrafish Kidney

Neurotrophins and their receptors are involved in the development and maintenance of neuronal populations. Different reports have shown that all neurotrophin/receptor pathways can also play a role in several non-neuronal tissues in vertebrates, including the kidney. These signaling pathways are involved in different events to ensure the correct functioning of the kidney, such as growth, differentiation, and regulation of renal tubule transport. Previous studies in some fish species have identified the neurotrophins and receptors in the kidney. In this study, for the first time, we compare the expression profiles (mRNA and protein) of all neurotrophin/receptor pathways in the kidney of the adult zebrafish. We quantify the levels of mRNA by using qPCR and identify the expression pattern of each neurotrophin/receptor pathway by in situ hybridization. Next, we detect the proteins using Western blotting and immunohistochemistry. Our results show that among all neurotrophins analyzed, NT-3/TrkC is the most expressed in the glomerule and tubule and in the hematopoietic cells, similar to what has been reported in the mammalian kidney.

Nephrotoxicity in advanced thyroid cancer treated with tyrosine kinase inhibitors: An update

Over the past decade, the prognosis of advanced thyroid cancer (TC) patients has dramatically improved thanks to the introduction of tyrosine kinase inhibitors (TKIs). Despite their effectiveness, these drugs are burdened with several side effects that can negatively affect quality of life and compromise therapy continuation. Among renal adverse events (RAEs), proteinuria is the most frequently reported in clinical trials and real-life experiences, especially during treatment with lenvatinib or cabozantinib. This peculiar toxicity is commonly associated with targeted therapies with anti-angiogenic activity, even if the mechanisms underlying its onset and progression are not entirely clear. RAEs should be early recognized and properly managed to avoid renal function worsening and life-threatening consequences. Aiming at providing a comprehensive summary that can help clinicians to identify and manage TKIs-related RAEs in TC patients, we reviewed the current evidence about this topic, from pathogenesis and potential risk factors to diagnosis and treatment.