Nuclear transfer of perchloric acid–soluble protein by endoplasmic reticulum stressors

Abstract

Perchloric acid-soluble protein (PSP) is highly conserved during evolution from bacteria to mammals. Although PSP has been recognized as an inhibitor of translation and proliferation in vitro, its precise biological role has not yet been elucidated. Since we previously found similar distributions for PSP and the endoplasmic reticulum (ER) and Golgi complex, the intracellular distribution of PSP was analyzed in more detail. Immunofluorescence studies indicated that PSP co-localized with the ER and Golgi complex, since the distribution pattern of PSP was well matched to both of these organelles. An immunoelectron microscopic study revealed PSP was located not only in the cytosol but also on the surface of the outer ER membrane. Since PSP was present on the ER, we speculated that it may be associated with ER function. Therefore, we analyzed whether or not the ER stress response, which is one of the ER functions, affected PSP expression. The results showed that various ER stressors (thapsigargin, A23187, tunicamycin, brefeldin A, and cisplatin) provoked a dramatic change in the localization of PSP from outside of the nucleus to inside the nucleus within 3 h. Moreover, the ER stressors induced PSP expression. These results suggest that PSP is involved in the cellular response to ER stressors, and that the change in localization of PSP from the ER to the nucleus may be associated with ER stress responses.Keywords: perchloric acid; soluble protein; m-calpain; endoplasmic reticulum; ER stress; thapsigargin Perchloric acid-soluble protein (PSP) was initially isolated from the rat liver as a translational inhibitor (Oka et al. 1995). Subsequently, it was also found in various other species, including humans (Schmiedeknecht et al. (Kaneki et al. 2003b), and so on. Since its gene (a member of the YER057c/YJGF family) is highly conserved during evolution, PSP may play important roles in the cell. In mammals, PSP has been reported to be associated with various functions, including ribonuclease activity (Morishita et al. 1999;Sawasaki et al. 2001), fatty acid-binding activity (Sasagawa et al. 1999), differentiation-dependent expression (Oka et al. 1995;Asagi et al. 1998;Nordin et al. 2001;Suzuki et al. 2001;Kaneki et al. 2003a), and repression of proliferation . However, the precise biological function of PSP has not yet been elucidated. Reprint requests to: Hiroaki Kanouchi, Department of Biochemistry, Kawasaki Medical School, 577 Matsushima, Kurashiki-city, Okayama, 701-0192, Japan; e-mail: kanouchihiroaki@mac.com; fax: +81-86-462-1199.Abbreviations: PSP, perchloric acid-soluble protein; ER, endoplasmic reticulum; GRP78, 78 kDa glucose regulated protein/BiP; D-PSP, Dorosophia ortholog PSP.Article published online ahead of print. Article and publication date are at http://www.proteinscience.org/cgi

A Putative New Role of Tv-PSP1 Recognizes IRE and ERE Hairpin Structures from Trichomonas vaginalis

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Electrophoretic pattern of the polypeptide component in the tight DNA-protein complexes in rat and chicken tissues and its partial characterisation in rat liver

“…Another enzyme identified among TBPs, ribonuclease UK114 is expressed in kidney and liver. Expression of this ribonuclease decreases during transformation of the cells and it is transferred to the nucleus in response to stress (Kanouchi et al, 2005). Several proteins involved in regulation of transcription were also found among the TBPs.…”

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

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“…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. In the case of liver regeneration, PSP perhaps needs to be down-regulated and then deleted from the nuclei to enter from the G 0 phase into the proliferation phase cells.…”