OBJECTIVETo investigate the role of sulfated tyrosine in regulating the activity of tyrosylprotein sulfotransferases (TPST) 1 and TPST2.

METHODSConstructs of TPST 1 and TPST2 were amplified by polymerase chain reaction (PCR), then fused into immunoglobulin G1 Fc region. All the variants in which sulfated tyrosines were mutated to phenylalanine were made by the PCR-based Quick Change method and confirmed by sequencing the entire reading frame. Small hairpin RNA (shRNA) constructs-targeting nucleotides 259-275 of TPST1 and nucleotides 73-94 of TPST2 were generated and subcloned into pBluescript. Human embryonic kidney (HEK) 293T cells were transfected with these plasmids. One day later, cells were split: one part was labeled with 35S-cysteine and methionine or 35S-Na2SO3 overnight, the second part was used for 125I labeled binding experiment, and the third part was retained for binding and flow cytometry.

RESULTSTyrosines at position 326 of TPST1 and position 325 of TPST2 were sulfated posttranslationally. Tyrosine sulfation of TPSTs was effectively inhibited by sulfation inhibitors, including specific shRNAs and non-specific NaCIO3. shRNAs reduced the sulfation of C3a receptor and C5a receptor, and partially blocked the binding of these two receptors to their respective ligands.

CONCLUSIONSThe activities of TPSTs were regulated by tyrosine sulfation. Inhibition of sulfotyrosine decreases the binding ability of C3a receptor and C5a receptor to their respective ligands.

Cell Line ; Complement C3a ; metabolism ; Complement C5a ; metabolism ; Humans ; Protein Binding ; Protein Processing, Post-Translational ; Receptor, Anaphylatoxin C5a ; metabolism ; Receptors, Complement ; metabolism ; Sulfotransferases ; genetics ; metabolism ; Transfection ; Tyrosine ; analogs & derivatives ; metabolism

To report a novel mutation within the CHST6 gene, as well as describe light and electron microscopic features of a case of macular corneal dystrophy. A 59-year old woman with macular corneal dystrophy in both eyes who had decreased visual acuity underwent penetrating keratoplasty. Further studies including light and electron microscopy, as well as DNA analysis were performed. Light microscopy of the cornea revealed glycosaminoglycan deposits in the keratocytes and endothelial cells, as well as extracellularly within the stroma. All samples stained positively with alcian blue, colloidal iron, and periodic acid-Schiff. Electron microscopy showed keratocytes distended by membrane-bound intracytoplasmic vacuoles containing electron-dense fibrillogranular material. These vacuoles were present in the endothelial cells and between stromal lamellae. Some of the vacuoles contained dense osmophilic whorls. A novel homozygous mutation (c.613 C>T [p.Arg205Trp]) was identified within the whole coding region of CHST6. A novel CHST6 mutation was detected in a Korean macular corneal dystrophy patient.
Corneal Dystrophies, Hereditary/diagnosis/*genetics/metabolism ; Corneal Keratocytes/ultrastructure ; DNA/*genetics ; DNA Mutational Analysis ; Female ; Humans ; Microscopy, Electron ; Middle Aged ; *Mutation, Missense ; Pedigree ; Polymerase Chain Reaction ; Republic of Korea ; Sulfotransferases/*genetics/metabolism