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: Toru Uyama, Katsuhisa Kawai, Nozomu Kono, Masahiro Watanabe, Kazuhito Tsuboi, Tomohito Inoue, Nobukazu Araki, Hiroyuki Arai, Natsuo Ueda
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 290 Issue 28 Pg. 17520-34 (Jul 10 2015) ISSN: 1083-351X [Electronic] United States
• PMID: 26018079 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Lipoproteins
• Membrane Proteins
• PEX16 protein, human
• Peroxins
• Pex3 protein, human
• Recombinant Proteins
• Tumor Suppressor Proteins
• PEX19 protein, human
• PLAAT3 protein, human
• Phospholipases A2, Calcium-Independent

Topics

• Animals
• COS Cells
• Chlorocebus aethiops
• Down-Regulation
• HEK293 Cells
• Humans
• Lipoproteins (chemistry, genetics, metabolism)
• Membrane Proteins (chemistry, genetics, metabolism)
• Models, Biological
• Peroxins
• Peroxisomes (metabolism)
• Phospholipases A2, Calcium-Independent (chemistry, genetics, metabolism)
• Protein Interaction Domains and Motifs
• Recombinant Proteins (chemistry, genetics, metabolism)
• Tumor Suppressor Proteins (chemistry, genetics, metabolism)