Characterization of Rab32- and Rab38-positive lysosome-related organelles in osteoclasts and macrophages

Kazuya Noda; Shiou-Ling Lu; Siyu Chen; Kanako Tokuda; Yangjie Li; Feike Hao; Yoh Wada; Ge-Hong Sun-Wada; Shinya Murakami; Mitsunori Fukuda; Takashi Itoh; Takeshi Noda

doi:10.1016/j.jbc.2023.105191

Characterization of Rab32- and Rab38-positive lysosome-related organelles in osteoclasts and macrophages

J Biol Chem. 2023 Oct;299(10):105191. doi: 10.1016/j.jbc.2023.105191. Epub 2023 Aug 23.

Authors

Kazuya Noda¹, Shiou-Ling Lu², Siyu Chen², Kanako Tokuda³, Yangjie Li², Feike Hao², Yoh Wada⁴, Ge-Hong Sun-Wada⁵, Shinya Murakami⁶, Mitsunori Fukuda⁷, Takashi Itoh², Takeshi Noda⁸

Affiliations

¹ Department of Oral Cell Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Osaka, Japan; Department of Periodontology, Graduate School of Dentistry, Osaka University, Osaka, Japan.
² Department of Oral Cell Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Osaka, Japan.
³ Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.
⁴ Department of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan; Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan.
⁵ Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College, Kyoto, Japan.
⁶ Department of Periodontology, Graduate School of Dentistry, Osaka University, Osaka, Japan.
⁷ Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Miyagi, Japan.
⁸ Department of Oral Cell Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Osaka, Japan; Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan; Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan. Electronic address: noda.takeshi.dent@osaka-u.ac.jp.

Abstract

Both the biogenesis and functions of osteoclasts and macrophages involves dynamic membrane traffic. We screened transcript levels for Rab family small GTPases related to osteoclasts and identified Rab38. Rab38 expression is upregulated during osteoclast differentiation and maturation. In osteoclasts, both Rab38 and its paralog, Rab32, colocalize to lysosome-related organelles (LROs). In macrophages, Rab32 is also found in LROs. LROs are part of the endocytic pathway but are distinct from lysosomes. After receptor activator of NF-κB ligand stimulation, LROs contain cathepsin K and tartrate-resistant acid phosphatase inside and help both proteins to accumulate around bone resorption pits. After osteoclast maturation, these enzymes are hardly found within LROs. In macrophages derived from Rab32 and Rab38 double knockout mice, both acidification and V-ATPase a3 localization were severely compromised. Both the double knockout macrophage and bafilomycin-treated wildtype macrophage show an increase in Lamp1-positive organelles, implying that biogenesis of lysosomes and LROs are related. These results indicate that Rab32 and Rab38 both play a crucial role in LRO biogenesis in macrophages and in osteoclasts.

Keywords: Rab32; Rab38; lysosome-related organelles; macrophage; osteoclast.