The L-type amino acid transporter LAT1 inhibits osteoclastogenesis and maintains bone homeostasis through the mTORC1 pathway

Kakeru Ozaki (Lead / Corresponding author), Takanori Yamada, Tetsuhiro Horie, Atsushi Ishizaki, Manami Hiraiwa, Takashi Iezaki, Gyujin Park, Kazuya Fukasawa, Hikari Kamada, Kazuya Tokumura, Mei Motono, Katsuyuki Kaneda, Kazuma Ogawa, Hiroki Ochi, Shingo Sato, Yasuhiro Kobayashi, Yun-Bo Shi, Peter M. Taylor, Eiichi Hinoi

Research output: Contribution to journalArticle

Abstract

L-type amino acid transporter 1 (LAT1), which is encoded by solute carrier transporter 7a5 (Slc7a5), plays a crucial role in amino acid sensing and signaling in specific cell types, contributing to the pathogenesis of cancer and neurological disorders. Amino acid substrates of LAT1 have a beneficial effect on bone health directly and indirectly, suggesting a potential role for LAT1 in bone homeostasis. Here, we identified LAT1 in osteoclasts as important for bone homeostasis. Slc7a5 expression was substantially reduced in osteoclasts in a mouse model of ovariectomy-induced osteoporosis. The osteoclast-specific deletion of Slc7a5 in mice led to osteoclast activation and bone loss in vivo, and Slc7a5 deficiency increased osteoclastogenesis in vitro. Loss of Slc7a5 impaired activation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway in osteoclasts, whereas genetic activation of mTORC1 corrected the enhanced osteoclastogenesis and bone loss in Slc7a5-deficient mice. Last, Slc7a5 deficiency increased the expression of nuclear factor of activated T cells, cytoplasmic 1 (Nfatc1) and the nuclear accumulation of NFATc1, a master regulator of osteoclast function, possibly through the canonical nuclear factor κB pathway and the Akt-glycogen synthase kinase 3β signaling axis, respectively. These findings suggest that the LAT1-mTORC1 axis plays a pivotal role in bone resorption and bone homeostasis by modulating NFATc1 in osteoclasts, thereby providing a molecular connection between amino acid intake and skeletal integrity.

Original languageEnglish
Article numberaaw3921
Pages (from-to)1-14
Number of pages14
JournalScience Signaling
Volume12
Issue number589
DOIs
Publication statusPublished - 9 Jul 2019

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Ozaki, K., Yamada, T., Horie, T., Ishizaki, A., Hiraiwa, M., Iezaki, T., Park, G., Fukasawa, K., Kamada, H., Tokumura, K., Motono, M., Kaneda, K., Ogawa, K., Ochi, H., Sato, S., Kobayashi, Y., Shi, Y-B., Taylor, P. M., & Hinoi, E. (2019). The L-type amino acid transporter LAT1 inhibits osteoclastogenesis and maintains bone homeostasis through the mTORC1 pathway. Science Signaling, 12(589), 1-14. [aaw3921]. https://doi.org/10.1126/scisignal.aaw3921