Changes in the Expression of Bone Morphogenetic Protein 7 and Tamm– Horsfall Protein in the Early Stages of Diabetic Nephropathy

BACKGROUND: Bone morphogenetic protein 7 (BMP7) has been suggested to play a protective role against kidney injury in chronic kidney disease. OBJECTIVES: To identify the critical molecular regulators in the early stage of diabetic nephropathy, we studied the expression of BMP7 and 2 important kidney-specific markers, podocin and Tamm-Horsfall protein (THP). MATERIALS AND METHODS: A diabetic nephropathy model was established by intraperitoneally injecting streptozotocin (STZ) in male Kunming mice. Kidney weight index was used as an indicator of early renal injury. Kidney tissue from the diabetic model mice was obtained at 4, 8, and 12 weeks, and total protein was extracted to assess the expression of BMP7, podocin, and THP by western blot analysis. RESULTS: Diabetic model mice were successfully established, and the kidney weight index of the model animals increased significantly. The expression of BMP7 was significantly downregulated, while the expression of THP was increased in the early stage of diabetic nephropathy. However, the expression of podocin did not change. CONCLUSIONS: Our observations suggested that down-regulation of BMP7 expression and up-regulation of THP expression were early events that occur prior to podocyte injury with the structure protein, podocin spoiled, which further confirmed that BMP7 is a key molecular regulator in the early stage of diabetic nephropathy.