Project description:To determine how TORC1 and PKA cooperate to regulate cell growth, we performed temporal analysis of gene expression in yeast switched from a non-fermentable substrate, to glucose, in the presence and absence of TORC1 and PKA inhibitors. Quantitative analysis of these data reveals that PKA drives the expression of key cell growth genes during transitions into, and out of, the rapid growth state in glucose, while TORC1 is important for the steady-state expression of the same genes.
Project description:The Target Of Rapamycin (TOR) protein is a Ser/Thr kinase that functions in two distinct multiprotein complexes: TORC1 and TORC2. These conserved complexes regulate many different aspects of cell growth in response to intra- and extracellular cues. Here we report the first bona fide substrate of yeast TORC1: the AGC-kinase Sch9. Six amino acids in the c-terminus of Sch9 are directly phosphorylated by TORC1. Phosphorylation of these residues is lost upon rapamycin-treatment as well as carbon- or nitrogen-starvation and transiently reduced following application of osmotic, oxidative or thermal stress. TORC1-dependent phosphorylation is required for Sch9 activity and replacement of residues phosphorylated by TORC1 with Asp/Glu renders Sch9 activity TORC1-independent. Sch9 is required for TORC1 to properly regulate ribosome biogenesis, translation initiation and entry into G0 phase, but not expression of Gln3-dependent genes. Our results suggest that Sch9 functions analogously to the mammalian TORC1 substrate S6K1 rather than the mTORC2 substrate PKB/Akt. Keywords: time course, cell type.
Project description:The Target Of Rapamycin (TOR) protein is a Ser/Thr kinase that functions in two distinct multiprotein complexes: TORC1 and TORC2. These conserved complexes regulate many different aspects of cell growth in response to intra- and extracellular cues. Here we report the first bona fide substrate of yeast TORC1: the AGC-kinase Sch9. Six amino acids in the c-terminus of Sch9 are directly phosphorylated by TORC1. Phosphorylation of these residues is lost upon rapamycin-treatment as well as carbon- or nitrogen-starvation and transiently reduced following application of osmotic, oxidative or thermal stress. TORC1-dependent phosphorylation is required for Sch9 activity and replacement of residues phosphorylated by TORC1 with Asp/Glu renders Sch9 activity TORC1-independent. Sch9 is required for TORC1 to properly regulate ribosome biogenesis, translation initiation and entry into G0 phase, but not expression of Gln3-dependent genes. Our results suggest that Sch9 functions analogously to the mammalian TORC1 substrate S6K1 rather than the mTORC2 substrate PKB/Akt. Keywords: time course, cell type. Global transcriptional analysis of rapamycin response was conducted on cells expressing either a wild-type, Sch9(WT), or TOR-independent allele of Sch9, Sch9(2D3E). Reference samples used were cells collected immediately prior to rapamycin treatment for the respective cell genotypes. Test samples were collected 20, 30, 60, 90, 120, and 180min post rapamycin treatment.
Project description:TOR kinase complex I (TORC1) is a key regulator of cell growth and metabolism in all eukaryotes. Previous studies in yeast have shown that three GTPases, Gtr1, Gtr2 and Rho1, bind TORC1 in nitrogen and amino acid starvation conditions to block phosphorylation of the S6 kinase Sch9 and activate protein phosphatase 2A (PP2A). This leads to down-regulation of 450 Sch9-dependent protein and ribosome synthesis genes, and up-regulation of 100 PP2A-dependent nitrogen assimilation and amino acid synthesis genes. Here, using bandshift assays and microarray measurements, we show that the TORC1 pathway also populates three other stress/starvation states. First, in glucose starvation conditions, the AMP activated protein kinase (AMPK/Snf1) and at least one other factor, push the TORC1 pathway into an off state where Sch9- branch signaling and PP2A-branch signaling are both inhibited. Remarkably, the TORC1 pathway remains in the glucose starvation (PP2A off) state even when cells are simultaneously starved for nitrogen and glucose. Second, in osmotic stress, the MAPK Hog1/p38 drives the TORC1 pathway into a different Sch9 off, PP2A off state, where PP2A-branch signaling can still be activated by nitrogen starvation. Third, in oxidative stress and heat stress, TORC1-Sch9 signaling is blocked while weak PP2A-branch signaling occurs. Together, our data show that the TORC1 pathway acts an information-processing hub, activating different genes in different conditions to ensure that available energy is allocated to drive growth, amino acid synthesis or a stress response, depending on the needs of the cell.
Project description:Snf1 and TORC1 are two global regulators that sense the nutrient availability and regulate the cell growth in yeast Saccharomyces cerevisiae. Here we undertook a systems biology approach to study the effect of deletion of these genes and investigate the interaction between Snf1 and TORC1 in regulation of gene expression and cell metabolism.
Project description:Temperature preference behavior in Drosophila depends on the level of PKA signaling in the mushroom bodies. To identify new components downstream to PKA, we carried out a genome-wide screen for genes regulated by PKA signaling in the mushroom bodies. Using the Gal4-UAS system, we increased or decreased PKA activity in the mushroom bodies by expressing dominant-negative (UAS-PKADN) or constitutively active PKA (UAS-PKACA), respectively. Expression of PKA transgenes was targeted to the mushroom bodies using the mushroom body-specific MB247-Gal4 driver. PKA expression was induced for 12-16 hours in three-day-old adults by inactivating the temperature-sensitive Gal80 at the restrictive temperature. We then analyzed gene-expression profiles to identify the genes showing altered expression levels in response to the high or low PKA activity.
Project description:Snf1 and TORC1 are two global regulators that sense the nutrient availability and regulate the cell growth in yeast Saccharomyces cerevisiae. Here we undertook a systems biology approach to study the effect of deletion of these genes and investigate the interaction between Snf1 and TORC1 in regulation of gene expression and cell metabolism. 3 mutant strains (snf1?, tor1?, snf1?tor1?) together with 1 reference strain grown under both glucose-limited or amonia-limited defined media with three biological replicates for each strain
Project description:Purpose: PKA plays a crucial role in vasopressin signaling of renal collecting duct cells. To understand regulation of mRNA expression mediated by vasopressin/PKA signaling, mRNA expression was profiled by RNA-Seq in double knockout cells (both PKA catalytic genes) generated from mouse cortical collecting duct mpkCCD cell line versus control lines with intact PKA expression. Methods: PKA double knockout (dKO) cell lines were generated from mouse cortical collecting duct mpkCCDc11 cells by CRISPR/Cas-9 genome editing method. For mRNA profiling using RNA-Seq analysis, three biological replicates of control (not mutated in PKA two catalytic subunits) cell lines and PKA double knockout cell lines were used. The reads uniquely mapped on GENCODE mouse gene set were analyzed with HOMER (v4.8) and edgeR (v3.10.5). Results and conclusion: About 40-50 million sequence reads per sample were sucessfully mapped in the mouse genome (GENCODE, GPCm38.p5). Among total transcripts of the mouse genome, 10,190 transcripts (cutoff: Counts Per Million > 4 by edgeR) were considered as genes expressed in the cell lines. In differential expression analysis by standard edgeR analysis, 354 transcripts were differentially expressed between control cell lines and PKA dKO cell lines (FDR < 0.05). We also identified nine genes that were markedly decreased in PKA dKO cell lines (log2 PKA dKO/Control < -2, FDR < 0.05) including aquaporin-2 (Aqp2) and two genes that were markedly increased in PKA dKO cell lines (log2 PKA dKO/Control > 2, FDR < 0.05). These results suggest PKA signaling is important for regulation of expression of a very limited number of genes in vasopressin-responsive renal collecting duct cells.
Project description:The regulatory subunit of cAMP-dependent protein kinase (PKA) exists in two isoforms, RI and RII, which distinguish the PKA isozymes, type I (PKA-I) and type II (PKA-II). Evidence obtained from a variety of different experimental approaches has shown that the relative levels of type I and type II PKA in cells can play a major role in determining the balance between cell growth and differentiation. RIα transfected cells exhibit hyper-proliferative growth and RIIβ transfected cells revert to a relatively quiescent state. Profiling by microarray revealed equally profound changes in gene expression between RIα, RIIβ, and parental OVCAR cells. Keywords: genetic modification