Immunoglobulin binding protein (BiP) function is required to protect cells from endoplasmic reticulum stress but is not required for the secretion of selective proteins
Immunoglobulin binding protein (BiP) function is required to protect cells from endoplasmic reticulum stress but is not required for the secretion of selective proteins
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DOI：
10.1074/jbc.272.7.4327
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发表时间：
1997-02-14
影响因子：
4.8
通讯作者：
Kaufman, RJ
中科院分区：
文献类型：
--
作者：
Morris, JA;Dorner, AJ;Kaufman, RJ
BiP/GRP 78是内质网（ER）的内腔应激蛋白，其与经过分泌室的多肽折叠中间体相互作用，我们研究了过表达野生型免疫球蛋白结合蛋白（BiP）或BiP缺失分子的中国仓鼠卵巢（CHO）细胞的分泌和应激反应（残基175-201），其可以结合肽和ATP，但在ATP水解和伴随的肽释放中有缺陷。过表达的野生型BiP定位于ER和细胞核内的独特囊泡，而过表达的ATP酶缺陷型BiP定位于ER和细胞质囊泡，但不在细胞核内。对于野生型CHO细胞，ATP酶缺陷型BiP的过表达阻止因子WI的分泌，在EB内腔中广泛结合BiP的凝血因子在这些条件下，因子VIII与ATP酶缺陷型BiP稳定结合。与此相反，单核细胞/巨噬细胞集落刺激因子的分泌，未检测到与BiP相关的蛋白质，不受ATP酶缺陷型BiP过表达的影响。这些结果表明，BiP功能不是某些蛋白质分泌所必需的，并且表明某些蛋白质在通过ER转运时不与BiP相互作用。ER中未折叠蛋白质的存在诱导BiP的转录，并且还引起蛋白质合成的一般抑制，野生型BiP的过度表达阻止了应激-钙离子载体A23187处理或衣霉素处理后BiP介导的转录诱导。相比之下，ATP酶缺陷型BiP的过表达不能阻止BiP的应激诱导，表明ATP酶活性是抑制转录诱导所必需的。野生型BiP的过表达，而不是ATP酶缺陷型BiP，增加了用A23187处理的细胞的存活。由过表达的野生型BiP介导的存活增加与响应于应激条件的翻译抑制减少相关，这些结果表明，过表达的BiP减轻了ER中的应激，以防止BiP转录诱导并允许细胞mRNA的持续翻译。
BiP/GRP78 is a lumenal stress protein of the endoplasmic reticulum (ER) that interacts with polypeptide folding intermediates transiting the secretory compartment, We have studied the secretion and the stress response in Chinese hamster ovary (CHO) cells that overexpress either wild-type immunoglobulin binding protein (BiP) or a BiP deletion molecule (residues 175-201) that can bind peptides and ATP but is defective in ATP hydrolysis and concomitant peptide release. Overexpressed wild-type BiP was localized to the ER and unique vesicles within the nucleus, whereas overexpressed ATPase-defective BiP was localized to the ER and cytoplasmic vesicles but was absent from the nucleus, Compared;with wild-type CHO cells, overexpression of ATPase-defective BiP prevented secretion of factor WI, a coagulation factor that extensively binds BiP in the lumen of the EB Under these conditions factor VIII was stably associated with the ATPase-defective BiP. In contrast, the secretion of monocyte/macrophage colony stimulating factor, a protein that is not detected in association with BiP, was not affected by overexpression of ATPase-defective BiP. These results show that BiP function is not required for secretion of some proteins and suggest that some proteins do not interact with BiP upon transport through the ER.The presence of unfolded protein in the ER induces transcription of BiP and also elicits a general inhibition of protein synthesis, Overexpression of wild-type BiP prevented the stress-mediated transcriptional induction of BiP in response to either calcium ionophore A23187 treatment or tunicamycin treatment. In contrast, overexpression of ATPase-defective BiP did not prevent the stress induction of BiP, showing that the ATPase activity is required to inhibit transcriptional induction, Overexpression of wild-type BiP, but not ATPase-defective BiP, increased survival of cells treated with A23187, The increased survival mediated by overexpressed wild-type BiP correlated with reduced translation inhibition in response to the stress condition, These results indicate that overexpressed BiP alleviated the stress in the ER to prevent BiP transcriptional induction and permit continued translation of cellular mRNAs.