Purification, Characterization and Differentiation-Dependent Expression of a Perchloric Acid Soluble Protein from Rat Kidney

Abstract

We have recently reported the presence of a novel perchloric acid soluble protein in rat liver (PSP1) that inhibits cell-free protein synthesis in a rabbit reticulocyte system. While studying the perchloric acid soluble proteins from different tissues of rats, we found that the kidney protein cross-reacted with antibody against the PSP1. In this investigation, we have purified a perchloric acid soluble protein from the rat kidney and studied its characterization and expression. The protein extracted from the postmitochondrial supernatant fraction with 5% perchloric acid was purified by ammonium sulfate fractionation and CM-Sephadex chromatography. By immunoscreening with the rabbit antisera against the PSP1, we detected a cDNA that contained an open reading frame of 411 bp, encoding a 137 amino-acid protein with a molecular mass of 14,149 daltons. The deduced amino acid sequence was completely identical with that of PSP1 from rat liver. The perchloric acid soluble protein from rat kidney (K-PSP1) also inhibited cell-free protein synthesis in the rabbit reticulocyte lysate system in a different manner than RNase A. Immunohistochemistry showed that the expression of K-PSP1 increased from fetal 17th day to postnatal 4th week, and it remained almost the same until the 7th week of postnatal age. Furthermore, the expression of K-PSP1 in the kidney of the nephrotic rat model was shown to be differentiation dependent. On the other hand, the expression of K-PSP1 in renal tumor cells was downregulated as compared with intact tissue. These results suggest that the expression of K-PSP1 is regulated in a differentiation-dependent manner in the kidney.

Y-Box Binding Protein 1 and RNase UK114 Mediate Monocyte Chemoattractant Protein 1 mRNA Stability in Vascular Smooth Muscle Cells

“…It shares a high degree of homology with other perchloric acid-soluble proteins (PSPs) extracted from the rat liver and kidney (2) and shows similarity to a newly hypothesized family of highly conserved proteins, YER057c/ YJGFs (22). Studies suggest that UK has multiple functions.…”

Decreased Expression of UK114 Is Related to the Differentiation Status of Human Hepatocellular Carcinoma

“…UK114 (also called translational inhibitor protein p14.5) has been purified from the perchloric acid -soluble fraction of goat liver (9). It shares a high degree of homology with other perchloric acid -soluble proteins (PSP) extracted from the rat liver and kidney (10,11) and shows similarity to the new hypothetical protein family, YER057c/YJGFs, which is highly conserved across the world range from prokaryotes to eukaryotes (12)(13)(14). The evolutionary conservation of these proteins implies that they may have an important cellular function.…”

“…A natural calpain activator protein has been isolated from the bovine brain and when characterized was found to be very similar to goat liver UK114 (16). Biological studies of its function suggest that it may play a role in cellular differentiation and development because levels are significantly increased during differentiation from human monocytes to macrophages (17) and during the development process of rat kidney, rat brain, pig liver, and chick liver (11,(18)(19)(20). Furthermore, expression of PSP depends on the proliferation states of the cell and overexpression of PSP reduces cell proliferation of normal rat kidney epithelial NRK-52E cells (21,22).…”

Reduced Expression of Perchloric Acid-Soluble Protein after Partial Hepatectomy in Rats

“…In kidney or liver cancer, PSP expression of malignant cells has been found to be lower than that of normal cells. 2,12) If we can discover how the expression and activity of PSP is regulated, a new strategy can be formulated to suppress abnormal cell proliferation. Hence, the liver regeneration model might be available for clarification of proliferation and maturation problems involving PSP.…”

“…[2][3][4][5] In fetal rat kidney, PSP was expressed in differentiated renal tubules but not in glomeruli. 2) In cultured cell lines, the expression of PSP was lower during the proliferation phase than during the confluent phase. 4) Overexpression of PSP inhibited cell proliferation in cultured cell lines.…”