title: High NaCl- and urea-induced posttranslational modifications that increase glycerophosphocholine by inhibiting GDPD5 phosphodiesterase.
abstract: Glycerophosphocholine (GPC) is high in cells of the renal inner medulla where high interstitial NaCl and urea power concentration of the urine. GPC protects inner medullary cells against the perturbing effects of high NaCl and urea by stabilizing intracellular macromolecules. Degradation of GPC is catalyzed by the glycerophosphocholine phosphodiesterase activity of glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5). We previously found that inhibitory posttranslational modification (PTM) of GDPD5 contributes to high NaCl- and urea-induced increase of GPC. The purpose of the present studies was to identify the PTM(s). We find at least three such PTMs in HEK293 cells: (i) Formation of a disulfide bond between C25 and C571. High NaCl and high urea increase reactive oxygen species (ROS). The ROS increase disulfide bonding between GDPD5-C25 and -C571, which inhibits GDPD5 activity, as supported by the findings that the antioxidant N-acetylcysteine prevents high NaCl- and urea-induced inhibition of GDPD5; GDPD5-C25S/C571S mutation or over expression of peroxiredoxin increases GDPD5 activity; H2O2 inhibits activity of wild type GDPD5, but not of GDPD5-C25S/C571S; and peroxiredoxin is relatively low in the renal inner medulla where GPC is high. (ii) Dephosphorylation of GDPD5-T587. GDPD5 threonine 587 is constitutively phosphorylated. High NaCl and high urea dephosphorylate GDPD5-T587. Mutation of GDPD5-T587 to alanine, which cannot be phosphorylated, decreases GPC-PDE activity of GDPD5. (iii) Alteration at an unknown site mediated by CDK1. Inhibition of CDK1 protein kinase reduces GDE-PDE activity of GDPD5 without altering phosphorylation at T587, and CDK1/5 inhibitor reduces activity of GDPD5- C25S/C571S-T587A.
authors.affiliation: Systems Biology Center, National Heart, Lung, and Blood Institute, Bethesda, MD 20892-1603, USA.
authors.forename: Supachai
authors.initials: S
authors.lastname: Topanurak
authors.forename: Joan D
authors.initials: JD
authors.lastname: Ferraris
authors.forename: Jinxi
authors.initials: J
authors.lastname: Li
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Izumi
authors.forename: Chester K
authors.initials: CK
authors.lastname: Williams
authors.forename: Marjan
authors.initials: M
authors.lastname: Gucek
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wang
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zhou
authors.forename: Maurice B
authors.initials: MB
authors.lastname: Burg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005997:Glycerylphosphorylcholine / Q000378:metabolism*; D006031:Glycosylation / Q000187:drug effects; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D054464:Peroxiredoxins / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D012965:Sodium Chloride / Q000494:pharmacology*; D014508:Urea / Q000494:pharmacology*
chemical_list: D008565:Membrane Proteins; D050505:Mutant Proteins; D010455:Peptides; D010726:Phosphodiesterase Inhibitors; D047428:Protein Kinase Inhibitors; D010769:Phosphothreonine; D012965:Sodium Chloride; D005997:Glycerylphosphorylcholine; D014508:Urea; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D018844:Cyclin-Dependent Kinases; D010727:Phosphoric Diester Hydrolases; C038133:glycerophosphodiester phosphodiesterase