De Wilde C, De Rycke R, Beeckman T, De Neve M, Van Montagu M, Engler G, Depicker A
Department of Genetics, Flanders Interuniversity Institute for Biotechnology, Universiteit Gent, Belgium.
Plant Cell Physiol. 1998 Jun;39(6):639-46. doi: 10.1093/oxfordjournals.pcp.a029416.
For the further optimization of antibody expression in plants, it is essential to determine the final accumulation sites of plant-made antibodies. Previously, we have shown that, upon secretion, IgG antibodies and Fab fragments can be detected in the intercellular spaces of leaf mesophyll cells of transgenic Arabidopsis thaliana plants. However, immunofluorescence microscopy showed that this is probably not their final accumulation site. In leaves, IgG and Fab fragments accumulate also at the interior side of the epidermal cell layers and in xylem vessels. These accumulation sites correspond with the leaf regions where water of the transpiration stream is entering a space impermeable to the proteins or where water is evaporating. In roots, plant-made Fab fragments accumulate in intercellular spaces of cortex cells, in the cytoplasm of pericycle and, to a lesser extent, endodermis cells, and in cells of the vascular cylinder. In other words, antibody accumulation occurs at the sites where water passes on its radial pathway towards and within the vascular bundle. Taken together, our results suggest that, upon secretion of plant-made antibodies or Fab fragments, a large proportion of these proteins are transported in the apoplast of A. thaliana, possibly by the water flow in the transpiration stream.
为进一步优化植物中抗体的表达，确定植物源抗体的最终积累位点至关重要。此前，我们已表明，分泌后，在转基因拟南芥植物叶片叶肉细胞的细胞间隙中可检测到IgG抗体和Fab片段。然而，免疫荧光显微镜显示这可能不是它们的最终积累位点。在叶片中，IgG和Fab片段也积累在表皮细胞层的内侧以及木质部导管中。这些积累位点与蒸腾流中的水进入蛋白质不可渗透空间或水蒸发的叶片区域相对应。在根中，植物源Fab片段积累在皮层细胞的细胞间隙、中柱鞘的细胞质中，以及较少程度地在内皮层细胞和维管束细胞中。换句话说，抗体积累发生在水沿其径向途径流向维管束并在维管束内流动的位点。综上所述，我们的结果表明，植物源抗体或Fab片段分泌后，这些蛋白质的很大一部分可能通过蒸腾流中的水流在拟南芥的质外体中运输。
