TRPM7 and MagT1 regulate the proliferation of osteoblast-like SaOS-2 cells through different mechanisms.

A correct magnesium (Mg) intake is essential for bone health. In particular, Mg deficiency inhibits the proliferation of osteoblast-like SaOS-2 cells by increasing nitric oxide (NO) production through the upregulation of inducible NO synthase. At the moment, little is known about the expression and the role of TRPM7, a channel/enzyme involved in Mg uptake, and MagT1, a Mg selective transporter, in SaOS-2 cells. Here, we demonstrate that TRPM7 is not modulated by different extracellular concentrations of Mg and its silencing exacerbates growth inhibition exerted by low Mg through the activation of inducible NO synthase and consequent accumulation of NO. Moreover, MagT1 is upregulated in SaOS-2 cultured in high Mg and its silencing inhibits the growth of SaOS-2 cultured in media containing physiological or high Mg, without any modulation of NO production. We propose that TRPM7 and MagT1 are both involved in regulating SaOS-2 proliferation through different mechanisms.