A Comparative Kidney Transcriptome Analysis of Bicarbonate-Loaded insrr-Null Mice.

The maintenance of plasma pH is critical for life in all organisms. The kidney plays a critical role in acid-base regulation in vertebrates by controlling the plasma concentration of bicarbonate. The receptor tyrosine kinase IRR (insulin receptor-related receptor) is expressed in renal ß-intercalated cells and is involved in alkali sensing due to its ability to autophosphorylate under alkalization of extracellular medium (pH > 7.9). In mice with a knockout of the insrr gene, which encodes for IRR, urinary bicarbonate secretion in response to alkali loading is impaired. The specific regulatory mechanisms in the kidney that are under the control of IRR remain unknown. To address this issue, we analyzed and compared the kidney transcriptomes of wild-type and insrr knockout mice under basal or bicarbonate-loaded conditions. Transcriptomic analyses revealed a differential regulation of a number of genes in the kidney. Using TaqMan real-time PCR, we confirmed different expressions of the slc26a4, rps7, slc5a2, aqp6, plcd1, gapdh, rny3, kcnk5, slc6a6 and atp6v1g3 genes in IRR knockout mice. Also, we found that the expression of the kcnk5 gene is increased in wild-type mice after bicarbonate loading but not in knockout mice. Gene set enrichment analysis between the IRR knockout and wild-type samples identified that insrr knockout causes alterations in expression of genes related mostly to the ATP metabolic and electron transport chain processes.

Changes in the Expression of the gapdh Gene in the Organs of insrr Knockout Mice.

The most important property of a living organism is the maintenance of optimal acid-base balance and the ionic composition of the internal environment. The kidneys are one of the main pH-regulating organs in the body. Receptor tyrosine kinase IRR (an insulin receptor-related receptor) is an alkaline pH-sensor. In mice (Mus Musculus) with a knockout of the insrr gene encoding the IRR receptor, bicarbonate secretion is impaired under the conditions of alkaline loading, which indicates the role of the receptor tyrosine kinase IRR in the regulation of acid-base balance in the body. In order to search for proteins functionally associated with the receptor tyrosine kinase IRR, we performed a large-scale sequencing of the mouse kidney transcriptome of wild type and insrr knockout mice kept under normal conditions and under alkaline conditions. As a result, we found a decrease in the gapdh gene expression in the kidneys of insrr knockout mice compared to wild type mice. RNA sequencing data were confirmed by TaqMan real-time PCR and Western blotting. Using the TaqMan real-time PCR method, we revealed a decrease in the level of gapdh expression not only in the kidneys, but also in the liver and brain of insrr knockout mice. Thus, the changes in the gapdh gene expression in the kidneys of insrr knockout mice may indicate a functional relationship between genes and a possible role of GAPDH in previously undescribed molecular mechanisms of regulation of acid-base balance in the body.