Expression and cellular distribution of perchloric acid-soluble protein is dependent on the cell-proliferating states of NRK-52E cells

Abstract

To clarify the biological role of kidney perchloric acid-soluble protein 1 (K-PSP1), its expression and intracellular distribution were examined in normal rat kidney epithelial NRK-52E cells. K-PSP1 expression was low during the proliferating phase and high in the stationary phase, and shown to have a negative relationship with the protein-synthesizing activity of the cells. Immunocytochemical studies revealed that K-PSP1 is predominantly located in the cytosol, especially in endoplasmic reticulum and Golgi apparatus of proliferating cells. In the stationary phase, K-PSP1 was not detected immunologically even though protein and mRNA expression were high. This disappearance of reactivity with anti-serum seems to be due to a conformational change in K-PSP1 induced by unknown factors. These results suggest that the role of K-PSP1 is to regulate cell proliferation, and this may be related to a previously reported ability to inhibit protein synthesis.

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

“…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

“…1) We have reported that PSP is related to cell proliferation and/or differentiation. [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.…”

“…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. 5) In chick embryos, PSP is expressed in the neuroepithelial cells at embryonic day 3.…”

“…Expression of PSP protein and mRNA was examined by the immunoblot and RT-PCR methods, as described previously. 1,4) Figure 1A shows PSP protein expression. Expression of PSP protein fell to half of that in the pretreated liver at day 2 of PH treatment, and expression of PSP gradually increased from day 3 of PH treatment.…”

“…Our previous results showed that PSP exists in the cytosol, endoplasmic reticulum (ER), or Golgi complex, but not in the nuclei in proliferating culture cells. 4,11) ER stresses induce a dramatic increase in the localization of PSP to the nuclei and in the induction of PSP expression. 11) We speculate that cell proliferation was suppressed under the ER-stress condition by induction of PSP expression and accumulation of PSP in the nuclei.…”