Characterization of MORN2 stability and regulatory function in LC3-associated phagocytosis in macrophages.

Microtubule-associated protein A1/B1-light chain 3 (LC3)-associated phagocytosis (LAP) is a type of non-canonical autophagy that regulates phagosome maturation in macrophages. However, the role and regulatory mechanism of LAP remain largely unknown. Recently, membrane occupation and recognition nexus repeat-containing-2 (MORN2) was identified as a key component of LAP for the efficient formation of LC3-recruiting phagosomes. To characterize MORN2 and elucidate its function in LAP, we established a MORN2-overexpressing macrophage line. At steady state, MORN2 was partially cleaved by the ubiquitin-proteasome system. MORN2 overexpression promoted not only LC3-II production but also LAP phagosome (LAPosome) acidification during Escherichia coli uptake. Furthermore, the formation of LAPosomes containing the yeast cell wall component zymosan was enhanced in MORN2-overexpressing cells and depended on reactive oxygen species (ROS). Finally, MORN2-mediated LAP was regulated by plasma membrane-localized soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) such as SNAP-23 and syntaxin 11. Taken together, these findings demonstrate that MORN2, whose expression is downregulated via proteasomal digestion, is a limiting factor for LAP, and that the membrane trafficking by SNARE proteins is involved in MORN2-mediated LAP. © 2020. Published by The Company of Biologists Ltd.

Citation

Maya Morita, Mayu Kajiye, Chiye Sakurai, Shuichi Kubo, Miki Takahashi, Daiki Kinoshita, Naohiro Hori, Kiyotaka Hatsuzawa. Characterization of MORN2 stability and regulatory function in LC3-associated phagocytosis in macrophages. Biology open. 2020 Jan 01

PMID: 34004723

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