Lysosomal activity under Normoxia and Hypoxia in macrophages
See details in Sekine, et. al. (2024) Nat Metab.
Hiroki Sekine, Haruna Takeda, Norihiko Takeda, Akihiro Kishino, Hayato Anzawa, Takayuki Isagawa, Nao Ohta, Shohei Murakami, Hideya Iwaki, Nobufumi Kato, Shu Kimura, Zun Liu, Koichiro Kato, Fumiki Katsuoka, Masayuki Yamamoto, Fumihito Miura, Takashi Ito, Masatomo Takahashi, Yoshihiro Izumi, Hiroyuki Fujita, Hitoshi Yamagata, Takeshi Bamba, Takaaki Akaike, Norio Suzuki, Kengo Kinoshita, Hozumi Motohashi (2024) PNPO-PLP axis senses prolonged hypoxia in macrophages by regulating lysosomal activity., Nature metabolism
Published in 2024 May 31 (Electronic publication in May 31, 2024, midnight )
(Abstract) Oxygen is critical for all metazoan organisms on the earth and impacts various biological processes in physiological and pathological conditions. While oxygen-sensing systems inducing acute hypoxic responses, including the hypoxia-inducible factor pathway, have been identified, those operating in prolonged hypoxia remain to be elucidated. Here we show that pyridoxine 5'-phosphate oxidase (PNPO), which catalyses bioactivation of vitamin B6, serves as an oxygen sensor and regulates lysosomal activity in macrophages. Decreased PNPO activity under prolonged hypoxia reduced an active form of vitamin B6, pyridoxal 5'-phosphate (PLP), and inhibited lysosomal acidification, which in macrophages led to iron dysregulation, TET2 protein loss and delayed resolution of the inflammatory response. Among PLP-dependent metabolism, supersulfide synthesis was suppressed in prolonged hypoxia, resulting in the lysosomal inhibition and consequent proinflammatory phenotypes of macrophages. The PNPO-PLP axis creates a distinct layer of oxygen sensing that gradually shuts down PLP-dependent metabolism in response to prolonged oxygen deprivation.