title: Apoptosis induced by an uromodulin mutant C112Y and its suppression by topiroxostat.
abstract: BACKGROUND
  Familial juvenile hyperuricemic nephropathy (FJHN) is an autosomal dominant disorder caused by mutations in UMOD that encodes uromodulin. Topiroxostat, a novel non-purine analog, selectively inhibits xanthine oxidase and reduces the serum uric acid levels and the urinary albuminuria.
  
  
  METHODS
  Genomic DNA of a patient was extracted from peripheral white blood. Exons and flanking sequences of UMOD were amplified by PCR with primers. Mutation analysis was performed by direct sequencing of the PCR products. The wild-type and mutant uromodulin were expressed in HEK293 cells and analyzed by western blotting, immunoprecipitation, immunofluorescence, and flow cytometry.
  
  
  RESULTS
  We identified an FJHN patient who carried a novel UMOD mutation G335A (C112Y). The levels of both cytosolic and secreted C112Y protein were significantly decreased compared with the wild-type, whereas the level of ubiquitination was higher in C112Y than that in the wild type. The half-life of C112Y was shortened and it was restored by a proteasome inhibitor MG132. Immunofluorescence revealed decreased levels of C112Y in the Golgi apparatus and on the plasma membrane. Expression of C112Y induced cellular apoptosis as revealed by flow cytometry. Apoptosis induced by C112Y was suppressed by topiroxostat.
  
  
  CONCLUSIONS
  C112Y causes its protein instability resulting cellular apoptosis which could be suppressed with topiroxostat.
authors.affiliation: Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Science, 86 Nishichou, Yonago, 683-8503, Japan.
authors.forename: Sulistiyati Bayu
authors.initials: SB
authors.lastname: Utami
authors.forename: Endang
authors.initials: E
authors.lastname: Mahati
authors.forename: Peili
authors.initials: P
authors.lastname: Li
authors.forename: Nani
authors.initials: N
authors.lastname: Maharani
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Ikeda
authors.forename: Udin
authors.initials: U
authors.lastname: Bahrudin
authors.forename: Chishio
authors.initials: C
authors.lastname: Munemura
authors.forename: Makoto
authors.initials: M
authors.lastname: Hosoyamada
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Akio
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Katsumi
authors.initials: K
authors.lastname: Higaki
authors.forename: Eiji
authors.initials: E
authors.lastname: Nanba
authors.forename: Haruaki
authors.initials: H
authors.lastname: Ninomiya
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Shirayoshi
authors.forename: Kimiyoshi
authors.initials: K
authors.lastname: Ichida
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Hosoya
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hisatome
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000187:drug effects*; D006073:Gout / Q000188:drug therapy / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D033461:Hyperuricemia / Q000188:drug therapy / Q000235:genetics*; D007674:Kidney Diseases / Q000188:drug therapy / Q000235:genetics*; D008297:Male; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology / Q000627:therapeutic use*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology / Q000627:therapeutic use*; D058949:Uromodulin / Q000235:genetics*
chemical_list: D009570:Nitriles; D011725:Pyridines; C548612:UMOD protein, human; D058949:Uromodulin; C504882:FYX-051; D046988:Proteasome Endopeptidase Complex