title: Orm protein phosphoregulation mediates transient sphingolipid biosynthesis response to heat stress via the Pkh-Ypk and Cdc55-PP2A pathways.
abstract: Sphingoid intermediates accumulate in response to a variety of stresses, including heat, and trigger cellular responses. However, the mechanism by which stress affects sphingolipid biosynthesis has yet to be identified. Recent studies in yeast suggest that sphingolipid biosynthesis is regulated through phosphorylation of the Orm proteins, which in humans are potential risk factors for childhood asthma. Here we demonstrate that Orm phosphorylation status is highly responsive to sphingoid bases. We also demonstrate, by monitoring temporal changes in Orm phosphorylation and sphingoid base production in cells inhibited for yeast protein kinase 1 (Ypk1) activity, that Ypk1 transmits heat stress signals to the sphingolipid biosynthesis pathway via Orm phosphorylation. Our data indicate that heat-induced sphingolipid biosynthesis in turn triggers Orm protein dephosphorylation, making the induction transient. We identified Cdc55-protein phosphatase 2A (PP2A) as a key phosphatase that counteracts Ypk1 activity in Orm-mediated sphingolipid biosynthesis regulation. In total, our study reveals a mechanism through which the conserved Pkh-Ypk kinase cascade and Cdc55-PP2A facilitate rapid, transient sphingolipid production in response to heat stress through Orm protein phosphoregulation. We propose that this mechanism serves as the basis for how Orm phosphoregulation controls sphingolipid biosynthesis in response to stress in a kinetically coupled manner.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Yidi
authors.initials: Y
authors.lastname: Sun
authors.forename: Yansong
authors.initials: Y
authors.lastname: Miao
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yamane
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.forename: Kevan M
authors.initials: KM
authors.lastname: Shokat
authors.forename: Hiromu
authors.initials: H
authors.lastname: Takematsu
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Kozutsumi
authors.forename: David G
authors.initials: DG
authors.lastname: Drubin
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013107:Sphingolipids / Q000096:biosynthesis*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D013696:Temperature
chemical_list: C071246:CDC55 protein, S cerevisiae; D018797:Cell Cycle Proteins; C548539:Orm1 protein, S cerevisiae; C548540:Orm2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013107:Sphingolipids; D011494:Protein Kinases; C060388:YPK2 protein, S cerevisiae; D064413:3-Phosphoinositide-Dependent Protein Kinases; C118385:PKH1 protein, S cerevisiae; C118386:PKH2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D038362:Glycogen Synthase Kinase 3; C068124:MCK1 protein, S cerevisiae; D054648:Protein Phosphatase 2; D013110:Sphingosine; C005682:safingol