The expression of Galectin‐9 correlates with mTOR and AMPK in murine colony‐forming erythroid progenitors

Objectives Galectin‐9 (Gal‐9) is an immune checkpoint ligand for T‐cell immunoglobulin and mucin domain 3. Although the roles of Gal‐9 in regulating immune responses have been well investigated, their biological roles have yet to be fully documented. This study aimed to analyse the expression of Gal‐9 bone marrow (BM) cells in C57BL/6J (B6) mice. Furthermore, the co‐expression of Gal‐9 with the mammalian target of rapamycin (mTOR) and AMP‐activated protein kinase (AMPK) was investigated. Methods The BM cells in adult C57BL/6J (B6) mice were collected and analysed in vitro. Results In a flow cytometric analysis of BM cells, Gal‐9 was highly expressed in c‐Kit hi Sca‐1 − CD34 − CD71 + erythroid progenitors (EPs), whereas it was downregulated in more differentiated c‐Kit lo CD71 + TER119 + cells. Subsequently, a negative selection of CD3 − B220 − Sca‐1 − CD34 − CD41 − CD16/32 − EPs was performed. This resulted in substantial enrichment of Kit hi CD71 + Gal‐9 + cells and erythroid colony‐forming units (CFU‐Es), suggesting that the colony‐forming subset of EPs are included in the Kit hi CD71 + Gal‐9 + population. Furthermore, we found that EPs had lower mTOR and AMPK expression levels in Gal‐9 knockout B6 mice than in wild‐type B6 mice. Conclusions These results may stimulate further investigation of the role of Gal‐9 in haematopoiesis.