The Mg2+ transporter MagT1 partially rescues cell growth and Mg2+ uptake in cells lacking the channel-kinase TRPM7

Magnesium (Mg2+) transport across membranes plays an essential role in cellular growth and survival. TRPM7 is the unique fusion of a Mg2+ permeable pore with an active cytosolic kinase domain, and is considered a master regulator of cellular Mg2+ homeostasis. We previously found that the genetic deletion of TRPM7 in DT40 B cells results in Mg2+ deficiency and severe growth impairment, which can be rescued by supplementation with excess extracellular Mg2+. Here, we show that gene expression of the Mg2+ selective transporter MagT1 is upregulated in TRPM7−/− cells. Furthermore, overexpression of MagT1 in TRPM7−/− cells augments their capacity to uptake Mg2+, and improves their growth behavior in the absence of excess Mg2+.