In yeast TOR and PKA pathways both control cell growth but how TORC1 and PKA signaling are linked is unknown. Here we show that TORC1 inhibition prevents the phosphorylation of some but not all PKA targets. We further demonstrate that TORC1 controls PKA by inhibiting the phosphorylation of the PKA regulatory subunit BCY1 by the MAP kinase MPK1.

The endolysosomal system sustains the reabsorptive activity of specialized epithelial cells. Lysosomal storage diseases such as nephropathic cystinosis cause a major dysfunction of epithelial cells lining the kidney tubule, resulting in massive losses of vital solutes in the urine. The mechanisms linking lysosomal defects and epithelial dysfunction remain unknown, preventing the development of disease-modifying therapies. Here we demonstrate, by combining genetic and pharmacologic approaches, that lysosomal dysfunction in cystinosis results in defective autophagy-mediated clearance of damaged mitochondria. This promotes the generation of oxidative stress that stimulates Gα12/Src-mediated phosphorylation of tight junction ZO-1 and triggers a signaling cascade involving ZO-1-associated Y-box factor ZONAB, which leads to cell proliferation and transport defects. Correction of the primary lysosomal defect, neutralization of mitochondrial oxidative stress, and blockage of tight junction-associated ZONAB signaling rescue the epithelial function. We suggest a link between defective lysosome-autophagy degradation pathways and epithelial dysfunction, providing new therapeutic perspectives for lysosomal storage disorders.

These findings underscore the importance of considering dorsal and ventral hippocampus separately when conducting high-throughput molecular analyses, which has important implications for fundamental research as well as clinical studies.

Deregulation of mitochondrial network in terminally differentiated cells contributes to a broad spectrum of disorders. Methylmalonic acidemia (MMA) is one of the most common inherited metabolic disorders, due to deficiency of the mitochondrial methylmalonyl-coenzyme A mutase (MMUT). How MMUT deficiency triggers cell damage remains unknown, preventing the development of disease-modifying therapies. Here we combine genetic and pharmacological approaches to demonstrate that MMUT deficiency induces metabolic and mitochondrial alterations that are exacerbated by anomalies in PINK1/Parkin-mediated mitophagy, causing the accumulation of dysfunctional mitochondria that trigger epithelial stress and ultimately cell damage. Using drug-disease network perturbation modelling, we predict targetable pathways, whose modulation repairs mitochondrial dysfunctions in patient-derived cells and alleviate phenotype changes in mmut-deficient zebrafish. These results suggest a link between primary MMUT deficiency, diseased mitochondria, mitophagy dysfunction and epithelial stress, and provide potential therapeutic perspectives for MMA. 1 1234567890():,;Mitochondrial dysfunction drives stress in MMA cells. As MMUT deficiency alters mitochondrial homeostasis, we next assessed potential consequences on mitochondrial function. Consistent with increased numbers of morphologically aberrant mitochondria, the mitochondrial membrane potential (Δψ m ) was drastically reduced in MMA cells (Fig. 2d), as evidenced by live cell imaging analyses of the mitochondrial network with cellpermeant, fluorescent dye tetramethylrhodamine methyl ester (TMRM, which readily accumulates within functional mitochondria) and MitoTracker (a fluorescent probe that localizes to mitochondria). These changes were paralleled by a major mitochondrial oxidative stress ( Fig. 2e), as testified by the elevated production of mitochondria (mt)-derived ROS (MitoSOX, a livecell-permeant indicator of mitochondrial ROS) and augmented antioxidant response (SOD1; Fig. 2g). Treatment with the mitochondrial complex I inhibitor Rotenone (5 μM for 24 h), which ARTICLE NATURE COMMUNICATIONS | https://doi.

Inflammation has a recognized role in nonalcoholic fatty liver disease (NAFLD) progression. In the present work, we studied the effect of high-fat diet (HFD) on arachidonic acid metabolism in the liver and investigated the role of the farnesoid X receptor (FXR, NR1H4) in eicosanoid biosynthetic pathways and nuclear factor light-chain enhancer of activated B cells (NF-kB) signaling, major modulators of the inflammatory cascade. Mice were fed an HFD to induce NAFLD and then treated with the FXR ligand obeticholic acid (OCA). Histology and gene expression analyses were performed on liver tissue. Eicosanoid levels were measured from serum and urine samples. The molecular mechanism underlying the effect of FXR activation on arachidonic acid metabolism and NF-kB signaling was studied in human liver Huh7 cells and primary cultured hepatocytes. NAFLD was characterized by higher (∼25%) proinflammatory [leukotrienes (LTB)] and lower (∼3-fold) anti-inflammatory [epoxyeicosatrienoic acids (EETs)] eicosanoid levels than in chow mice. OCA induced the expression of several hepatic cytochrome P450 (P450) epoxygenases, the enzymes responsible for EET synthesis, and mitigated HFD-induced hepatic injury. In vitro, induction of CYP450 epoxygenases was sufficient to inhibit NF-kB signaling and cell migration. The CYP450 epoxygenase pan-inhibitor gemfibrozil fully abolished the protective effect of OCA, indicating that OCA-mediated inhibition of NF-kB signaling was EET-dependent. In summary, NAFLD was characterized by an imbalance in arachidonate metabolism. FXR activation reprogramed arachidonate metabolism by inducing P450 epoxygenase expression and EET production. In vitro, FXR-mediated NF-kB inhibition required active P450 epoxygenases.