Interaction of Phospholipase A/Acyltransferase-3 with Pex19p: A POSSIBLE INVOLVEMENT IN THE DOWN-REGULATION OF PEROXISOMES.
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.
['Uyama|Toru|T|', 'Kawai|Katsuhisa|K|', 'Kono|Nozomu|N|', 'Watanabe|Masahiro|M|', 'Tsuboi|Kazuhito|K|', 'Inoue|Tomohito|T|', 'Araki|Nobukazu|N|', 'Arai|Hiroyuki|H|', 'Ueda|Natsuo|N|']
D000818:Animals D019556:COS Cells D002522:Chlorocebus aethiops D015536:Down-Regulation D057809:HEK293 Cells D006801:Humans D008074:Lipoproteins D008565:Membrane Proteins D008954:Models, Biological D000074401:Peroxins D020675:Peroxisomes D054512:Phospholipases A2, Calcium-Independent D054730:Protein Interaction Domains and Motifs D011994:Recombinant Proteins D025521:Tumor Suppressor Proteins
phospholipase A peroxisome H-rev107 peroxin HRAS-like suppressor glycerophospholipid organelle phospholipase A/acyltransferase (PLA/AT) tumor suppressor gene