Rapalogs, inhibitors of mTORC1 (mammalian target of rapamycin complex 1), increase life span and delay age-related phenotypes in many species. However, the molecular mechanisms have not been fully elucidated. We determined gene expression changes comparing 6- and 24-month-old rats in the kidney, liver, and skeletal muscle, and asked which of these changes were counter-regulated by a clinically-translatable (short-term and low-concentration) treatment, with a rapalog (RAD001). Surprisingly, RAD001 had a more pronounced effect on the kidney under this regimen in comparison to the liver or skeletal muscle. Histologic evaluation of kidneys revealed that the severity of chronic progressive nephropathy lesions was lower in kidneys from 24-month-old rats treated with RAD001 compared with vehicle. In addition to other gene expression changes, c-Myc, which has been shown to regulate aging, was induced by aging in the kidney and counter-regulated by RAD001. RAD001 caused a decrease in c-Myc protein, which could be rescued by a proteasome inhibitor. These findings point to settings for use of mTORC1 inhibitors to treat age-related disorders, and highlight c-Myc regulation as one of the potential mechanisms by which mTORC1 inhibition is perturbing age-related phenotypes. Overall design: Transcriptional profiling was performed in kidney, liver and gastrocnemius muscles from three experimental groups of male Sprague Dawley rats. Rats aged 4.5 month (m) and 22.5 m were treated with vehicle and rats aged 22.5 m were treated with RAD001 for 6 weeks, with a read-out at 6 and 24 months.
Short-term Low-Dose mTORC1 Inhibition in Aged Rats Counter-Regulates Age-Related Gene Changes and Blocks Age-Related Kidney Pathology.
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View SamplesAberrant activation of -catenin is a common event in Acute Myeloid Leukemia (AML), and is recognized as an independent predictor of poor prognosis. Although increased -catenin signaling in AML has been associated with AML1-ETO and PML-RAR translocation products, and activating mutations in the FLT3 receptor, it remains unclear which mechanisms activate -catenin in AML more broadly. Here, we describe a novel link between interleukin-3 (IL-3) signaling and the regulation of -catenin in myeloid transformation and AML. Using a murine model of HoxB8 and IL-3 cooperation we show that IL-3 modulates -catenin protein levels, and Cre-induced deletion of -catenin abolishes IL-3 dependent growth and colony formation. In the erythroleukemic cell line TF-1.8, we observed increased -catenin protein levels and nuclear localization in response to IL-3, which correlated with transcriptional induction of -catenin target genes. Furthermore, IL-3 promoted -catenin accumulation in a subset of AML patient samples, and microarray gene expression analysis of these cells revealed induction of WNT/-catenin and TCF4 transcriptional gene signatures in an IL-3 dependent manner. This study is the first to link -catenin activation to IL-3 and suggests that targeting IL-3 signaling may be an effective approach for the inhibition of -catenin activity in some patients with AML.
Interleukin-3-mediated regulation of β-catenin in myeloid transformation and acute myeloid leukemia.
Specimen part, Disease, Treatment
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