H2O2 stimulates Cl−/HCO 3− exchanger activity through oxidation of thiol groups in immortalized SHR renal proximal tubular epithelial cells

Abstract

Cl(-) /HCO (3)(-) exchanger and Na(+) /H(+) exchanger 3 are the main transporters responsible for NaCl reabsorption in kidney proximal tubules (PT). It is well accepted that membrane exchangers can be regulated by reactive oxygen species (ROS). In the kidney, ROS are known to contribute to decreases in Na(+) excretion and consequently increase blood pressure. The present study investigated mechanisms by which H(2) O(2) -induced stimulation of Cl(-) /HCO (3)(-) exchanger activity is enhanced in proximal tubular epithelial (PTE) cells immortalized from spontaneously hypertensive rats (SHR) as compared to normotensive Wistar Kyoto (WKY). H(2) O(2) decreased K(m) values for Cl(-) /HCO (3)(-) exchanger activity in SHR PTE cells, but had no effect on the kinetic parameters in WKY cells. DTDP stimulated in a concentration-dependent manner Cl(-) /HCO (3)(-) exchanger activity in both cell lines, but SHR PTE cells were 2.4-fold more responsive to this oxidant. In contrast, thimerosal had no effect on exchanger activity in both cell lines. The effects of H(2) O(2) and DTDP upon the exchanger activity were blocked by DTT in WKY and SHR PTE cells. Similar to H(2) O(2), DTDP decreased K(m) values for Cl(-) /HCO (3)(-) exchanger activity in SHR PTE cells. Basal content of free thiol groups was higher in WKY PTE cells than in SHR. Upon H(2) O(2) treatment the free thiol groups decreased in both cell lines; however, this decrease was more pronounced in WKY cells. In conclusion, in SHR PTE cells H(2) O(2) stimulates Cl(-) /HCO (3)(-) exchanger activity via modification of thiol groups of intracellular and/or transmembrane protein. Furthermore, the thiol oxidation-dependent pathway also increases the HCO (3)(-) affinity in SHR PTE cells.

Renal amino acid transport systems and essential hypertension

“…In fact, in immortalized SHR PTE cells, H 2 O 2 has been shown to stimulate Cl Ϫ /HCO 3 Ϫ exchanger activity via modification of thiol groups of intracellular and/or transmembrane proteins. The oxidized conformation of the exchanger enhanced the affinity for HCO 3 Ϫ in immortalized SHR PTE cells but not in WKY PTE cells (93). Cysteine residues of proteins are especially susceptible to oxidative stress and, given the important role that disulfides play in protein structure and stability, alterations of reactive cysteine thiol groups may change protein function and activity.…”

Glutathione is an aging-related metabolic signature in the mouse kidney

“…It is widely accepted that oxidative stress contributes to tissue damage, thereby leading to pathological changes during the aging process. In both murine and human studies, researchers reported that aging was associated with increases in reactive oxygen species (ROS) generation and alterations in ROS removal ability [ 6 ]. Furthermore, renal oxidative stress is considered a major factor underlying the initiation of diabetic nephropathy [ 7 ].…”

Genetic polymorphisms associated with reactive oxygen species and blood pressure regulation

“…ROS can regulate ion transport 16–18,23,35–64 . Superoxide, produced by NADPH oxidase, enhances NaCl transport in the renal proximal tubule 16,17,39,44,45,59 , thick ascending limb of Henle 41,46,48 , and collecting duct 18,47,48 . The voltage-gated proton channel participates in the increased production of superoxide in the renal outer medulla of Dahl salt-sensitive rats 46 .…”

“…Increased ROS production is involved in the pathogenesis of many 1,5,8–17,22,23,25,28–44,48,57,60,62–64,68,71,72,86,89,92,104,138,140–154,162,163,173,189,197,210,214,218,219,221–233,236–244,246–252,262,263 270–273,278–280,295,305329–331 ,.…”