Geranylgeranylacetone, an inducer of the 70-kDa heat shock protein (HSP70), elicits unfolded protein response and coordinates cellular fate independently of HSP70
Geranylgeranylacetone, an inducer of the 70-kDa heat shock protein (HSP70), elicits unfolded protein response and coordinates cellular fate independently of HSP70
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DOI：
10.1124/mol.107.039164
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发表时间：
2007-11-01
影响因子：
3.6
通讯作者：
Kitamura, Masanori
中科院分区：
文献类型：
--
作者：
Endo, Satoshi;Hiramatsu, Nobuhiko;Kitamura, Masanori
香叶酮（GGA）是一种抗溃疡剂，能够在各种细胞类型中诱导70 kda热休克蛋白（HSP70），并保护细胞免受凋亡性损伤。然而，GGA对其他热休克蛋白家族分子的影响知之甚少。我们发现，在浓度>= 100 mu M时，GGA可引起78 kda葡萄糖调节蛋白（GRP78）的选择性表达，GRP78是内质网（ER）应激诱导的HSP70家族成员，而不影响各种细胞类型的HSP70水平。另一个内源标记CCAAT/增强子结合蛋白同源蛋白（CHOP）的表达也证实了GGA诱导内质网应激；内质网应激反应性碱性磷酸酶活性降低；未折叠蛋白反应（UPR），包括激活转录因子6 （ATF6）途径和肌醇要求ER-to-nucleus signal kinase 1- x- box-binding protein 1 （IRE1-XBP1）途径的激活。用GGA孵育系膜细胞可引起明显的细胞凋亡，转染caspase-12抑制剂（即caspase-12和MAGE-3的显性阴性突变体）可减轻细胞凋亡。IRE1或XBP1的显性阴性抑制可显著减弱细胞凋亡，且不影响CHOP和GRP78的水平。1,9-吡唑啉王座（SP600125）对IRE1下游分子c-Jun NH(2)末端激酶的抑制作用并未改善细胞存活。4-（2-氨基乙基）苯磺酰氟阻断ATF6可增强GGA诱导的细胞凋亡，并与GRP78和CHOP的诱导减弱相关。GRP78过表达或CHOP的显性阴性抑制显著减弱gga诱导的细胞凋亡。这些结果表明，GGA可以触发促凋亡（IRE1-XBP1, ATF6-CHOP）和抗凋亡（ATF6-GRP78） UPR，从而在不诱导HSP70的情况下协调细胞命运。
Geranylgeranylacetone (GGA), an antiulcer agent, has the ability to induce 70-kDa heat shock protein (HSP70) in various cell types and to protect cells from apoptogenic insults. However, little is known about effects of GGA on other HSP families of molecules. We found that, at concentrations >= 100 mu M, GGA caused selective expression of 78-kDa glucose-regulated protein (GRP78), an HSP70 family member inducible by endoplasmic reticulum (ER) stress, without affecting the level of HSP70 in various cell types. Induction of ER stress by GGA was also evidenced by expression of another endogenous marker, CCAAT/enhancer-binding protein-homologous protein (CHOP); decreased activity of ER stress-responsive alkaline phosphatase; and unfolded protein response (UPR), including activation of the activating transcription factor 6 (ATF6) pathway and the inositol-requiring ER-to-nucleus signal kinase 1-X-box-binding protein 1 (IRE1-XBP1) pathway. Incubation of mesangial cells with GGA caused significant apoptosis, which was attenuated by transfection with inhibitors of caspase-12 (i.e., a dominant-negative mutant of caspase-12 and MAGE-3). Dominant-negative suppression of IRE1 or XBP1 significantly attenuated apoptosis without affecting the levels of CHOP and GRP78. Inhibition of c-Jun NH(2)-terminal kinase, the molecule downstream of IRE1, by 1,9-pyrazoloanthrone (SP600125) did not improve cell survival. Blockade of ATF6 by 4-(2-aminoethyl) benzenesulfonyl fluoride enhanced apoptosis by GGA, and it was correlated with attenuated induction of both GRP78 and CHOP. Overexpression of GRP78 or dominant-negative inhibition of CHOP significantly attenuated GGA-induced apoptosis. These results suggested that GGA triggers both proapoptotic (IRE1-XBP1, ATF6-CHOP) and antiapoptotic (ATF6-GRP78) UPR and thereby coordinates cellular fate even without induction of HSP70.