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

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.

The BM cells in adult C57BL/6J (B6) mice were collected and analysed in vitro.

In a flow cytometric analysis of BM cells, Gal-9 was highly expressed in c-Kit^hiSca-1^-CD34^-CD71⁺ erythroid progenitors (EPs), whereas it was downregulated in more differentiated c-Kit^loCD71⁺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^hiCD71⁺Gal-9⁺ cells and erythroid colony-forming units (CFU-Es), suggesting that the colony-forming subset of EPs are included in the Kit^hiCD71⁺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.

These results may stimulate further investigation of the role of Gal-9 in haematopoiesis.