"Since phosphorylation of ribosomal S6 is thought to be specific to TORC1 signalling, we decided to look further into its phosphorylation. It has previously been demonstrated that the anti-PAS antibody, which recognises phosphorylation of the [R/ K]X[R/K]XX[S/T] consensus motif in mammalian S6K1 and other AGC kinase substrates (Manning et al., 2002; Pearson and Kemp, 1991) (Cell Signalling Technology), detects phosphorylation of fission yeast Rps6 serine 235 (Nakashima et al., 2010). Ribosomal S6 is encoded by two genes in fission yeast: rps601 and rps602. "
[Show abstract][Hide abstract] ABSTRACT: TOR (Target Of Rapamycin) signalling coordinates cell growth and division in response to changes in the nutritional environment of the cell. TOR kinases form two distinct complexes: TORC1 and TORC2. In mammals, the TORC1 controlled S6K1 kinase phosphorylates the ribosomal protein S6 thereby co-ordinating cell size and nutritional status. We show that the Schizosaccharomyces pombe AGC kinase Gad8 co-immunoprecipitates with the ribosomal protein S6 (Rps6) and regulates its phosphorylation status. It has previously been shown that Gad8 is phosphorylated by TORC2. Consistent with this, we find that TORC2 as well as TORC1 modulates Rps6 phosphorylation. Therefore, S6 phosphorylation in fission yeast actually represents a read-out of the combined activities of TORC1 and TORC2. In contrast, we find that the in vivo phosphorylation status of Maf1 (a repressor of RNA polymerase III) specifically correlates with TORC1 activity.
Biology Open 09/2012; 1(9):884-8. DOI:10.1242/bio.20122022 · 2.42 Impact Factor
"Multiplexed analysis permits synchronous, parallelized multiple sampling and testing from the same tissue lysate, thus making it a powerful analytical tool. In addition to biochemical measures of phosphate incorporation using ATP as a substrate, a number of high-throughput methods generally using antibody detection of phosphopeptide products have been perfected   . Recently, interest has shifted to inhibitors with an appropriate pattern of kinase inhibition that includes several kinases as the target . "
[Show abstract][Hide abstract] ABSTRACT: The serine/threonine kinase Akt (PKB) is activated in response to growth factors, cytokines and other growth promoting stimuli and is involved in the regulation of a number of cellular processes including metabolism, cell growth, proliferation and survival. To study intracellular metabolic effects of left ventricular hypertrophy (LVH) induced by chronic aortic banding in a recently established swine model, protein arrays can be used to analyze changes in cytosolic protein phosphorylation levels such as cell signal transduction and protein kinase pathways. Miniaturized sandwich immunoassays allow the simultaneous analysis of several parameters in a single experiment. Bead-based protein array systems or suspension microarrays are well-established multiplex sandwich immunoassay formats. Cytosolic proteins were extracted from pig hearts. Using the bead-based Luminex system, multiplexed sandwich immunoassays have been developed to analyze the phosphorylated proteins IR[pYpY1162/1163], IGF-1R[pYpY1135 /1136], IRS-1[pS312], Akt[pS473], PRAS40[pT246], p70S6K[pTpS421/424], and GSK-3[pS9], which were measured simultaneously in extracted myocardial tissue homogenates with the Akt Pathway Phospho 7-Plex Panel using a Luminex 100 IS system. Using this assay, tissue homogenates derived from myocardial tissue samples from 28 individual porcine in vivo model experiments in normal hearts (n=17) and LVH hearts (n=11) were analyzed for phosphorylated protein concentrations. Results obtained allowed grouping of myocardial tissue samples into a LVH and a normal group. Two candidate molecules: PRAS40 (normal vs. LVH two-tailed probability P= 0.0022) and GSK-3 (P=0.003), had lower concentrations in LVH pigs than in normal animals, suggesting loss of GSK-3 inhibitory activity and contributing to speculation of altered insulin sensitivity associated with LVH.
Current Signal Transduction Therapy 01/2011; 2011(6):65-70. · 0.45 Impact Factor
"Recently, also the nonhuman herpesvirus Pseudorabies Virus (PRV) U S 3 kinase was shown to induce phosphorylation of HDAC2 on serine 407, indicating a conserved effect of many herpesviruses on this deacetylase . The kinase(s) directly responsible for HDAC1 and HDAC2 phosphorylations in vivo is unknown; CKII seems unlikely to be the cellular kinase involved, since it requires the acidic consensus sequence S/T- X-X-E , not present in the region encompassing serines 406 of HDAC1 and 407 of HDAC2. CKII-dependent phosphorylation of HDAC1 and HDAC2 is also increased in response to hypoxic conditions, and this correlates with an increase in HDAC enzymatic activity . "
[Show abstract][Hide abstract] ABSTRACT: Class I histone deacetylases (HDACs) are cellular enzymes expressed in many tissues and play crucial roles in differentiation, proliferation, and cancer. HDAC1 and HDAC2 in particular are highly homologous proteins that show redundant or specific roles in different cell types or in response to different stimuli and signaling pathways. The molecular details of this dual regulation are largely unknown. HDAC1 and HDAC2 are not only protein modifiers, but are in turn regulated by post-translational modifications (PTMs): phosphorylation, acetylation, ubiquitination, SUMOylation, nitrosylation, and carbonylation. Some of these PTMs occur and crosstalk specifically on HDAC1 or HDAC2, creating a rational "code" for a differential, context-related regulation. The global comprehension of this PTM code is central for dissecting the role of single HDAC1 and HDAC2 in physiology and pathology.
BioMed Research International 01/2011; 2011:690848. DOI:10.1155/2011/690848 · 2.71 Impact Factor
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