As a host for recombinant protein expression, plants have their own advantages over microorganisms and animal cells. When plant cells are used to express recombinant proteins, the extracellular secretion of recombinant proteins can simplify the purification process thereby reducing production costs. In view of the low efficiency of secretion mediated by traditional secretion signal peptides, this study attempted to increase the secretion rate by using the exocyst-positive organelle (EXPO) in the non-traditional secretion pathway. The results showed that overexpression of the Arabidopsis EXO70E2 gene could increase the secretion rate and production of enhanced green fluorescent protein located in the endoplasmic reticulum (ER) or secretory pathway but had no significant effect on the one located in the cytoplasm. In order to increase the effect of EXO70E2, this study further optimized the culture conditions of stable transformed cell lines through design of experiment. The verification on two recombinant proteins, IL10 and trastuzumab, confirmed that the co-expression of EXO70E2 combined with the optimization of culture conditions can increase the secretion rate and yield of these recombinant proteins, providing a new strategy for the development of plant bioreactors.

植物作为重组蛋白表达的宿主，比微生物和动物细胞有其自身的优势。当利用植物细胞表达重组蛋白时，重组蛋白的胞外分泌可以简化纯化过程，从而降低生产成本。鉴于传统分泌信号肽介导的分泌效率较低，本研究尝试利用非传统分泌途径中的外囊阳性细胞器（EXPO）来提高分泌率。结果表明，拟南芥过表达EXO70E2基因可以增加位于内质网(ER)或分泌途径的增强型绿色荧光蛋白的分泌率和产量，但对位于细胞质的增强型绿色荧光蛋白没有显着影响。为了增强EXO70E2的效果，本研究通过实验设计进一步优化了稳定转化细胞系的培养条件。对IL10和曲妥珠单抗两种重组蛋白的验证证实，EXO70E2的共表达结合培养条件的优化可以提高这些重组蛋白的分泌率和产量，为植物生物反应器的开发提供了新的策略。