engleski

Immunolocalization of G-protein-coupled receptors for succinate (GPR91) and alpha-ketoglutarate (GPR99) in the human nephron

G-protein-coupled receptors GPR91 and GPR99 may in the mammalian nephron function as controlers of blood pressure via affecting the activity of renin-angiotensin system after sensing local levels of succinate and alpha-ketoglutarate, respectively. mRNA for both receptors was highly expressed and localized to the proximal (GPR91) and distal (GPR99) tubules of the mouse kidney, but the exact localization of receptor proteins along the mammalian nephron is unknown. In this study we tested several commercial polyclonal antibodies against human GPR91 and GPR99 for their efficiency to label these receptors in the human kidney by Western blotting (WB) of isolated total cell membranes and by immunocytochemistry (IC) in tissue cryosections. By WB, the optimal antibodies from both groups labeled in reducing conditions a single protein band of ~90 kDa. By IC, the optimal GPR91-antibody stained: a) the basolateral domain of thick ascending limbs of Henle, which were distinguished from the glucose transporter (hSGLT1)-positive proximal tubule S3 segments, and b) intercalated cells in the inner medullary collecting duct, where it colocalized with the vacuolar-ATPase. The GPR99-antibodies stained only the brush-border of cortical proximal tubules. Therefore, GPR 91 and GPR99 are differently localized in the mouse and human nephron, which may indicate different function(s).

dicarboxylate receptors; human kidney; nephron; renal tubules; immunocytochemistry

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