title: Geldanamycin interferes with the 90-kDa heat shock protein, affecting lipopolysaccharide-mediated interleukin-1 expression and apoptosis within macrophages.
abstract: We have demonstrated that lipopolysaccharide (LPS)-mediated reactive oxygen species (ROS) and signal transduction are involved in the regulation of interleukin-1 (IL-1) beta gene expression within macrophages. Because the 90-kDa heat shock protein (Hsp90) plays an important role in the LPS mediation of macrophage activation, using Hsp90 inhibitor geldanamycin A (GA), we analyzed the mechanism of Hsp90 upon LPS-transduced signaling in the regulation of IL-1 expression and determined the function of Hsp90 regarding the viability of human primary macrophages and murine macrophages cell line. In essence, GA decreased LPS-induced Hsp90/pp60Src heterocomplex formation. In addition, Hsp90 is important for IL-1 protein translation, plays a minor role in IL-1 mRNA transcription, and is involved in nuclear factor-kappaB activation and the phosphorylation and activation of p38, c-Jun NH2-terminal kinase, and extracellular signal-regulated kinase; however, Hsp90 plays a more important role in LPS-stimulated p38 activation. In analyzing the function of Hsp90 regarding the cytotoxicity/viability of macrophages, we found that the combination of LPS and GA increases apoptosis, as evidenced by the increased caspase-3 activity and the proportion of nuclear/chromatin condensation. In contrast, N-acetyl-cysteine dramatically blocked GA/LPS-induced ROS production, simultaneously decreasing caspase-3 activity and the presence of apoptotic nuclei. We concluded that Hsp90 plays an indispensable role in the process of LPS-induced IL-1 secretion. Furthermore, we established the mechanism of GA interference with Hsp90 function for LPS-stimulated macrophages, resulting in increased ROS production and caspase-3 activation, and consequently leading to synergistic enhancement of macrophage apoptosis.
authors.affiliation: Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, 155 Li-Nong Street, Shih-Pai Taipei, Taiwan. hyhsu@ym.edu.tw
authors.forename: Hsien-Yeh
authors.initials: HY
authors.lastname: Hsu
authors.forename: Hua-Lin
authors.initials: HL
authors.lastname: Wu
authors.forename: Sai-Koong
authors.initials: SK
authors.lastname: Tan
authors.forename: Vivian Pei-Hsin
authors.initials: VP
authors.lastname: Li
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Wang
authors.forename: Jason
authors.initials: J
authors.lastname: Hsu
authors.forename: Ching-Hsun
authors.initials: CH
authors.lastname: Cheng
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016227:Benzoquinones / Q000494:pharmacology*; D002460:Cell Line; D018841:HSP90 Heat-Shock Proteins / Q000187:drug effects / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism*; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors
chemical_list: D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D053583:Interleukin-1beta; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides; D011505:Protein-Tyrosine Kinases; C001277:geldanamycin