TRPM7 residue S1269 mediates cAMP dependence of Ca(2+) influx

The nonspecific divalent cation channel TRPM7 (transient receptor potential-melastatin-like 7) is involved in many Ca(2+) and Mg(2+)-dependent cellular processes, including survival, proliferation and migration. TRPM7 expression predicts metastasis and recurrence in breast cancer and several other cancers. In cultured cells, it can induce an invasive phenotype by promoting Ca(2+)-mediated epithelial-mesenchymal transition. We previously showed that in neuroblastoma cells that overexpress TRPM7 moderately, stimulation with Ca(2+)-mobilizing agonists leads to a characteristic sustained influx of Ca(2+). Here we report that sustained influx through TRPM7 is abruptly abrogated by elevating intracellular levels of cyclic adenosine monophosphate (cAMP). Using pharmacological inhibitors and overexpression studies we show that this blockage is mediated by the cAMP effector Protein Kinase A (PKA). Mutational analysis demonstrates that the Serine residue S1269, which is present proximal to the coiled-coil domain within the protein c-terminus, is responsible for sensitivity to cAMP.