title: Microsatellite polymorphism located immediately upstream of the phosphatidylinositol glycan, class K gene (PIGK) affects its expression, which correlates with tyrosinase activity in human melanocytes.
abstract: BACKGROUND
  Glycosylphosphatidylinositol (GPI) acts as a membrane anchor and a post-translational modifier for more than 150 proteins (called GPI-anchored proteins: GPI-APs). However, little study has been done to explore the role of GPI-APs in melanocytes.
  
  
  METHODS
  The relationship between the mRNA expression of the genes which play essential roles in GPI anchoring system [phosphatidylinositol glycan, class A, and class K gene (PIGA, PIGK)] and melanogenesis-related genes (MITF, TYRP1, TYRP2, and TYR) as well as DOPA oxidase activities were evaluated in 13 different normal human epidermal melanocytes (NHEMs). A short tandem repeat (STR) polymorphism located in the predicted promoter region of PIGK was genotyped in the NHEMs. RNA interference experiment of PIGK was also conducted using one of the NHEMs.
  
  
  RESULTS
  PIGK mRNA expression in NHEMs were strongly in inverse correlation with TYR mRNA and DOPA oxidase activities. NHEMs with the STR polymorphism revealed a low level of PIGK expression. However, a transient knockdown of PIGK in NHEM failed to reveal significant changes in the expression of TYR mRNA and DOPA oxidase activity.
  
  
  CONCLUSIONS
  This report firstly demonstrated that inadequate protein-GPI anchoring caused by suppression of PIGK might affect the expression or function of some GPI-APs associated with tyrosinase activity.
authors.affiliation: Department of Dermatology, Yamagata University Faculty of Medicine, Yamagata, Japan. Electronic address: k-okamura@med.id.yamagata-u.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Okamura
authors.affiliation: Department of Dermatology, Yamagata University Faculty of Medicine, Yamagata, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hayashi
authors.affiliation: Department of Dermatology, Yamagata University Faculty of Medicine, Yamagata, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Abe
authors.affiliation: Department of Dermatology, Yamagata University Faculty of Medicine, Yamagata, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Araki
authors.affiliation: Department of Dermatology, Yamagata University Faculty of Medicine, Yamagata, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hozumi
authors.affiliation: Department of Dermatology, Yamagata University Faculty of Medicine, Yamagata, Japan.
authors.forename: Tamio
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D015815:Cell Adhesion Molecules / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics*; D055785:Gene Knockdown Techniques; D017261:Glycosylphosphatidylinositols / Q000235:genetics; D006801:Humans; D008544:Melanocytes / Q000201:enzymology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D051739:Microphthalmia-Associated Transcription Factor; D018895:Microsatellite Repeats / Q000235:genetics*; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D015815:Cell Adhesion Molecules; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D051739:Microphthalmia-Associated Transcription Factor; C491190:PIGK protein, human; D012333:RNA, Messenger; D010088:Oxidoreductases; C489799:TYRP1 protein, human; D014442:Monophenol Monooxygenase
keywords: GPI; Melanocyte; Microsatellite; PIGK; Tyrosinase activity