Abstract: TH-PO1024
Expression of Phosphate-Dependent Glutaminase (PDG) in Normal and Neoplastic Human Kidney
Session Information
- Acid Base: Basic
November 02, 2017 | Location: Hall H, Morial Convention Center
Abstract Time: 10:00 AM - 10:00 AM
Category: Fluid, Electrolytes, and Acid-Base
- 701 Acid-Base: Basic
Authors
- Lee, Hyun-Wook, University of Florida, Gainesville, Florida, United States
- Clapp, William L., University of Florida, Gainesville, Florida, United States
- Wakefield, Dara N., University of Florida, Gainesville, Florida, United States
- Verlander, Jill W., University of Florida, Gainesville, Florida, United States
- Weiner, I. David, University of Florida, Gainesville, Florida, United States
Background
Phosphate-dependent glutaminase (PDG) is a mitochondrial protein that has a critical role in renal ammonia metabolism, catalyzing the initial step in ammoniagenesis, and may have a role in glutamine-derived ATP generation. The cellular distribution of PDG in the human kidney is currently unknown. This study’s purpose was to determine PDG's cellular expression in normal and neoplastic human kidney.
Methods
We used human kidney tissues from unused portions of nephrectomy specimens removed during routine treatment of renal cell carcinoma for immunohistochemistry studies. Three separate PDG antibodies were used; all gave similar results. Normal human kidney protein lysates were obtained from commercial sources.
Results
Immunoblot analysis of both human whole kidney and cortical protein revealed an ~63 kDa protein. Immunohistochemistry showed PDG immunolabel throughout the nephron and in arterial walls in a granular pattern consistent with mitochondrial expression. Glomerular label was punctate and weak compared to tubules. Tubule distribution of PDG was verified using H+-ATPase and NKCC2 as markers. Strong PDG expression was present in proximal tubule, descending and ascending thin limb, thick ascending limb, distal convoluted tubule, connecting segment (CNT), and throughout the collecting duct (CD). Cellular heterogeneity in label intensity was evident in CNT and CD profiles. PDG expression in kidney neoplasms varied among tumor types. In tumors of presumed proximal tubule origin, clear cell and papillary renal cell carcinoma (RCC), weak, 1+, PDG immunolabel was present. In tumors of presumed intercalated cell tubule origin, oncocytoma and chromophobe RCC, PDG immunolabel was substantially more intense, 2-3+, and immunolabel intensity was greater in oncocytoma than in chromophobe RCC.
Conclusion
1) PDG is widely expressed in epithelial and non-epithelial cells in the human kidney. 2) PDG expression in RCC varies with tumor type; it is weakly expressed in clear cell and papillary RCC, whereas in oncocytoma and chromophobe RCC it is expressed more strongly. 3) This wide-spread expression suggests PDG may have critical roles both in ammoniagenesis and glutamine-derived ATP generation.
Funding
- NIDDK Support