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Abstract: PO0922

The Significance of Renal TSPAN9 Overexpression in Diabetic Nephropathy

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Tang, Xi, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Leverette, Desiree, Meharry Medical College, Nashville, Tennessee, United States
  • Harris, Raymond C., Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Yang, Haichun, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Fogo, Agnes B., Vanderbilt University Medical Center, Nashville, Tennessee, United States
Background

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. We performed proteomic analysis in isolated human glomeruli (DN vs. normal control) and RNAseq in glomeruli from a murine model of DN (db/db/eNOS-/-) vs. nondiabetic controls (eNOS-/-). We identified differentially expressed molecules with potential impact in DN, including tetraspanin 9 (TSPAN9), which mediates transduction signaling and regulates cell development, growth and motility. We investigated the potential contribution of TSPAN9 in DN.

Methods

Human kidney biopsies from DN (class II, III and IV, total n=30) were studied, and compared to control (non-cancer regions of human nephrectomy (Nx), n=10). TSPAN9 immunostaining was assessed and correlated with morphologic lesions and clinical data. Human mesangial cells (HMC) were cultured in normal glucose, mannitol or high glucose medium. TSPAN9 expression in HMC was determined by qPCR, western blot and immunofluorescence. HMC viability and migration were assessed by MTT assay and transwell experiments. Collagen IV protein in the cellular supernatant was detected by ELISA. Apoptosis regulating molecules Bax and BCL-2 were assessed by qPCR and western blot.

Results

TSPAN9 was expressed weakly in normal human kidney control, in glomerular mesangial areas and luminal side of tubules. Immunostaining intensity was gradually increased in class II, III and IV DN. TSPAN9 translocated from the luminal to apical side in tubular epithelial cells, and extended to more extracellular expression in mesangial areas. In DN samples, glomerular TSPAN-9 expression correlated with extent of glomerulosclerosis, hyalinosis, mesangial expansion and proteinuria, while tubular TSPAN-9 correlated with extent of interstitial fibrosis, proteinuria and serum creatinine. In vitro, TSPAN9 in HMC was significantly upregulated by mannitol and high glucose, accompanied by decreased cell viability, migration and increased apoptosis.

Conclusion

DN was associated with increased TSPAN9 overexpression and translocation in mesangial and tubular epithelial cells, respectively, and was associated with worse renal function and more severe structural injury.

Funding

  • NIDDK Support