Interaction of Phospholipase A/Acyltransferase-3 with Pex19p: A POSSIBLE INVOLVEMENT IN THE DOWN-REGULATION OF PEROXISOMES

• Published in: The Journal of biological chemistry Vol. 290; no. 28; pp. 17520 - 17534
• Main Authors: Uyama, Toru, Kawai, Katsuhisa, Kono, Nozomu, Watanabe, Masahiro, Tsuboi, Kazuhito, Inoue, Tomohito, Araki, Nobukazu, Arai, Hiroyuki, Ueda, Natsuo
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10-07-2015
• Subjects: Animals; Chlorocebus aethiops; COS Cells; Down-Regulation; HEK293 Cells; Humans; Lipids; Lipoproteins - chemistry; Lipoproteins - genetics; Lipoproteins - metabolism; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Models, Biological; Peroxins; Peroxisomes - metabolism; Phospholipases A2, Calcium-Independent - chemistry; Phospholipases A2, Calcium-Independent - genetics; Phospholipases A2, Calcium-Independent - metabolism; Protein Interaction Domains and Motifs; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Tumor Suppressor Proteins - chemistry; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; H-rev107; HRAS-like suppressor; phospholipase A; peroxin; organelle; phospholipase A/acyltransferase (PLA/AT); glycerophospholipid; peroxisome; tumor suppressor gene
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.635433

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.