Zhu Genyuan, Wang Miao, Spike Benjamin, Gray Peter C, Shen Jieli, Lee Sung-Hyung, Chen Si-Yi, Lee Amy S
Department of Biochemistry and Molecular Biology, University of Southern California, Keck School of Medicine, USC Norris Comprehensive Cancer Center, Los Angeles, CA, USA.
1] Department of Biochemistry and Molecular Biology, University of Southern California, Keck School of Medicine, USC Norris Comprehensive Cancer Center, Los Angeles, CA, USA [2].
Sci Rep. 2014 Jun 23;4:5390. doi: 10.1038/srep05390.
Glucose Regulated Protein (GRP) 94 and GRP78 are critical molecular chaperones and regulators of signaling. Conditional knockout mouse models have revealed tissue specific requirements for GRP94 and GRP78, including selection for allele retention in specific cell types. Here we report the consequences of mammary-targeted knockout of these GRPs. Our studies revealed that MMTV-Cre, Grp94(f/f) mammary glands, despite GRP94 deficiency, exhibited normal proliferation and ductal morphogenesis. Interestingly, MMTV-Cre, Grp78(f/f) mammary glands displayed only slightly reduced GRP78 protein levels, associating with the retention of the non-recombined Grp78 floxed alleles in isolated mammary epithelial cells and displayed phenotypes comparable to wild-type glands. In contrast, transduction of isolated Grp78(f/f) mammary epithelial stem/progenitor cells with adenovirus expressing GFP and Cre-recombinase was successful in GRP78 ablation, and the GFP sorted cells failed to give rise to repopulated mammary glands in de-epithelialized recipient mice. These studies imply GRP78, but not GRP94, is required for mammary gland development.
葡萄糖调节蛋白（GRP）94和GRP78是关键的分子伴侣和信号调节因子。条件性基因敲除小鼠模型揭示了GRP94和GRP78在组织中的特异性需求，包括在特定细胞类型中选择等位基因保留。在此，我们报告这些GRP在乳腺靶向敲除后的结果。我们的研究表明，MMTV-Cre、Grp94(f/f)乳腺，尽管缺乏GRP94，但仍表现出正常的增殖和导管形态发生。有趣的是，MMTV-Cre、Grp78(f/f)乳腺仅显示GRP78蛋白水平略有降低，这与分离的乳腺上皮细胞中未重组的Grp78 floxed等位基因的保留有关，并且表现出与野生型乳腺相当的表型。相比之下，用表达绿色荧光蛋白（GFP）和Cre重组酶的腺病毒转导分离的Grp78(f/f)乳腺上皮干/祖细胞成功实现了GRP78的敲除，并且经GFP分选的细胞在去上皮化的受体小鼠中未能产生重新填充的乳腺。这些研究表明，乳腺发育需要GRP78，而不是GRP94。
