Expression of Transient Receptor Potential Melastatin 7 Up-regulated in the Early Stage of Renal Ischemia-Reperfusion

Background. Transient receptor potential melastatin 7 (TRPM7), a bifunctional protein with kinase and ion channel activities, was first reported in 2001. Later studies suggested that the functions of TRPM7 related to cancer, ischemic injury, and hypertension. Methods. We examined whether TRPM7 expression changed in renal ischemia-reperfusion injury (RIRI). Seventy male Sprague-Dawley rats weighing 220-250 g were randomly divided into 7 groups of 7 rats each; every group had a sham-operated cohort of 3 rats. After the right kidney was removed, the rats underwent 45 minutes of left renal artery occlusion followed by reperfusion for 1, 12, 24, 48, 72, or 96 hours. There after the expression of trpm7 messenger RNA (mRNA) was measured using real-time polymerase chain reaction (RT-PCR) and the protein using Western blot. Results. Compared with the control group, the expression of trpm7 mRNA was significantly up-regulated at 24 hours after ischemia-reperfusion. We set the expression of trpm7 mRNA of the control group as the baseline (1.0), with the 1-hour, 12-hour, 24-hour, 48-hour, 72-hour and 96-hours showing 2.83, 3.16, 3.95, 0.31, 0.82, and 1.13, respectively (n = 7; P < .05). TRPM7 protein expression showed the same trends as the mRNA. The main change in TRPM7 protein was located in tubular cells. Conclusions. The expressions of trpm7 mRNA and protein levels was up-regulated at 24 hours after renal ischemia.