Real-time detection and continuous monitoring of ER stress in vitro and in vivo by ES-TRAP: evidence for systemic, transient ER stress during endotoxemia.
Activity of secreted alkaline phosphatase (SEAP) produced by transfected cells is rapidly down-regulated by endoplasmic reticulum (ER) stress independent of transcriptional regulation. This phenomenon was observed in a wide range of cell types triggered by various ER stress inducers. The magnitude of the decrease in SEAP was proportional to the extent of ER stress and inversely correlated with the induction of endogenous ER stress markers grp78 and grp94. In contrast to SEAP, activity of secreted luciferase was less susceptible to ER stress. The decrease in SEAP activity by ER stress was caused by abnormal post-translational modification, accelerated degradation and reduced secretion of SEAP protein. In transgenic mice constitutively producing SEAP, systemic induction of ER stress led to reduction in serum SEAP. In these mice, administration with lipopolysaccharide caused rapid, transient decrease in serum SEAP activity, and it was correlated with up-regulation of grp78 in several organs including the spleen, lung, kidney, liver and heart. These results elucidated for the first time a possible involvement of transient, systemic ER stress in endotoxemia and provided evidence for usefulness of ER stress responsive alkaline phosphatase for real-time monitoring of ER stress in vitro and in vivo.
Hiramatsu
Nobuhiko
N
Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan.
Kasai
Ayumi
A
Hayakawa
Kunihiro
K
Yao
Jian
J
Kitamura
Masanori
M
D000469:Alkaline Phosphatase / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D019446:Endotoxemia / Q000235:genetics / Q000378:metabolism*; D005334:Fever / Q000378:metabolism; D017930:Genes, Reporter; D006360:Heat-Shock Proteins / Q000378:metabolism; D008156:Luciferases / Q000032:analysis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018832:Molecular Chaperones / Q000378:metabolism; D051381:Rats
D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D018832:Molecular Chaperones; D008156:Luciferases; D000469:Alkaline Phosphatase