title: Interaction of Phospholipase A/Acyltransferase-3 with Pex19p: A POSSIBLE INVOLVEMENT IN THE DOWN-REGULATION OF PEROXISOMES.
abstract: Phospholipase A/acyltransferase (PLA/AT)-3 (also known as H-rev107 or AdPLA) was originally isolated as a tumor suppressor and was later shown to have phospholipase A1/A2 activity. We have also found that the overexpression of PLA/AT-3 in mammalian cells results in specific disappearance of peroxisomes. However, its molecular mechanism remained unclear. In the present study, we first established a HEK293 cell line, which stably expresses a fluorescent peroxisome marker protein (DsRed2-Peroxi) and expresses PLA/AT-3 in a tetracycline-dependent manner. The treatment with tetracycline, as expected, caused disappearance of peroxisomes within 24 h, as revealed by diffuse signals of DsRed2-Peroxi and a remarkable decrease in a peroxisomal membrane protein, PMP70. A time-dependent decrease in ether-type lipid levels was also seen. Because the activation of LC3, a marker of autophagy, was not observed, the involvement of autophagy was unlikely. Among various peroxins responsible for peroxisome biogenesis, Pex19p functions as a chaperone protein for the transportation of peroxisomal membrane proteins. Immunoprecipitation analysis showed that PLA/AT-3 binds to Pex19p through its N-terminal proline-rich and C-terminal hydrophobic domains. The protein level and enzyme activity of PLA/AT-3 were increased by its coexpression with Pex19p. Moreover, PLA/AT-3 inhibited the binding of Pex19 to peroxisomal membrane proteins, such as Pex3p and Pex11βp. A catalytically inactive point mutant of PLA/AT-3 could bind to Pex19p but did not inhibit the chaperone activity of Pex19p. Altogether, these results suggest a novel regulatory mechanism for peroxisome biogenesis through the interaction between Pex19p and PLA/AT-3.
authors.affiliation: From the Departments of Biochemistry and.
authors.forename: Toru
authors.initials: T
authors.lastname: Uyama
authors.affiliation: Histology and Cell Biology, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Kawai
authors.affiliation: the Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Kono
authors.affiliation: From the Departments of Biochemistry and Kagawa University Hospital, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan, and.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: From the Departments of Biochemistry and.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tsuboi
authors.affiliation: From the Departments of Biochemistry and the Department of Orthopedic Surgery, Shikoku Medical Center for Children and Adults, Zentsuji, Kagawa 765-0001, Japan.
authors.forename: Tomohito
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Histology and Cell Biology, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan.
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Araki
authors.affiliation: the Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
authors.affiliation: From the Departments of Biochemistry and nueda@med.kagawa-u.ac.jp.
authors.forename: Natsuo
authors.initials: N
authors.lastname: Ueda
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D015536:Down-Regulation; D057809:HEK293 Cells; D006801:Humans; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D000074401:Peroxins; D020675:Peroxisomes / Q000378:metabolism*; D054512:Phospholipases A2, Calcium-Independent / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D008074:Lipoproteins; D008565:Membrane Proteins; C486345:PEX16 protein, human; D000074401:Peroxins; C113138:Pex3 protein, human; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; C087343:PEX19 protein, human; C490065:PLAAT3 protein, human; D054512:Phospholipases A2, Calcium-Independent
keywords: H-rev107; HRAS-like suppressor; glycerophospholipid; organelle; peroxin; peroxisome; phospholipase A; phospholipase A/acyltransferase (PLA/AT); tumor suppressor gene