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

• Published in: Science signaling 2019-07, Vol.12 (589)
• Main Authors: Ozaki, Kakeru, Yamada, Takanori, Horie, Tetsuhiro, Ishizaki, Atsushi, Hiraiwa, Manami, Iezaki, Takashi, Park, Gyujin, Fukasawa, Kazuya, Kamada, Hikari, Tokumura, Kazuya, Motono, Mei, Kaneda, Katsuyuki, Ogawa, Kazuma, Ochi, Hiroki, Sato, Shingo, Kobayashi, Yasuhiro, Shi, Yun-Bo, Taylor, Peter M, Hinoi, Eiichi
• Format: Article
• Language: English
• Subjects: Accumulation; Activation; AKT protein; Amino acids; Biocompatibility; Biomedical materials; Bone density; Bone loss; Bone mass; Bone resorption; Bone turnover; Chemoreception; Clonal deletion; Glycogen; Glycogen synthase kinase 3; Homeostasis; Kinases; Lymphocytes; Mice; Neurological diseases; NF-AT protein; NF-κB protein; Osteoclastogenesis; Osteoclasts; Osteoporosis; Osteoprogenitor cells; Ovariectomy; Pathogenesis; Post-menopause; Rapamycin; Signal transduction; Signaling; Substrates; TOR protein; Transcription factors
• ISSN: 1945-0877; 1937-9145
• DOI: 10.1126/scisignal.aaw3921

L-type amino acid transporter 1 (LAT1), which is encoded by ( ), 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. expression was substantially reduced in osteoclasts in a mouse model of ovariectomy-induced osteoporosis. The osteoclast-specific deletion of in mice led to osteoclast activation and bone loss in vivo, and deficiency increased osteoclastogenesis in vitro. Loss of 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 -deficient mice. Last, deficiency increased the expression of nuclear factor of activated T cells, cytoplasmic 1 ( ) 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.