Korean J Phys Anthropol.  2017 Sep;30(3):87-98. 10.11637/kjpa.2017.30.3.87.

Alteration of Akt, p-Akt, ERK, and p-ERK Proteins Expression in the Kidney of Hypokalemic Rat

• Bae CS
• Cho HJ
• Ahn KY

• KMID: 2392274
• DOI: http://doi.org/10.11637/kjpa.2017.30.3.87

Abstract

Hypokalemia causes metabolic alkalosis and morphological changes of the kidney. K⁺ balance is regulated not only by ion channels or pump gene, but also by various genes including NF-E2-related factor 2 (Nrf2). Previous study suggested the possibility that Akt and ERK kinase may be involved in Nrf2 transcriptional gene activation. In present study, we investigate the alterations of Akt, p-Akt, ERK, p-ERK protein in both normal kidney and K⁺-deficient diet kidney using Western blot analysis, and immunohistochemisrty. Our western blot data showed that the expression of Akt and p-Akt was increased gradually in K⁺-depleted diet (from 1W-3W) compared to normal group. The expression of ERK and p-ERK was markedly increased in K⁺-depleted diet 2W in comparison with normal group. Based on our immunostaining results, Akt protein immunoreactivity was prominently increased in outer medullary collecting duct, especially in K⁺-depleted diet 2 weeks. The localization of p-Akt proteins in K⁺-depleted groups was not different from normal group, but the immunoreactivity was significantly increased in distal convoluted tubule, macula densa and outer medullary thick ascending limb in K⁺-depleted diet 1 and 2 weeks groups. ERK protein immunoreactivity was prominently increased in outer medullary collecting duct, especially in K⁺-depleted diet 2 and 3 weeks. The localization of p-ERK proteins in K⁺-depleted groups was not different from normal group, but the immunoreactivity was prominently increased in the nucleus of outer medullary collecting duct especially in K⁺-depleted diet 2 weeks. Taken together, we suggest that the expression of p-Akt was gradually increased in K⁺-depleted groups of kidney, but the expression of p-ERK was markedly increased in K⁺-depleted diet 2 week group. Hence, the promotion of AKT and ERK phosphorylation in hypokalemic condition may be involved in the regulation of ion channels, ion transporters and subsequent intracellular signal transduction.

Keyword

Hypokalemia; Metabolic alkalosis; Akt; p-Akt; ERK; p-ERK; Immunohistochemisty

MeSH Terms

Alkalosis
Animals
Blotting, Western
Diet
Extremities
Hypokalemia
Ion Channels
Ion Transport
Kidney*
NF-E2-Related Factor 2
Phosphorylation
Phosphotransferases
Rats*
Signal Transduction
Transcriptional Activation
Ion Channels
NF-E2-Related Factor 2
Phosphotransferases