Developmental Biology Research Initiatives, Department of Biology, McGill University, 1205 Dr Penfield Avenue, Montreal, Quebec H3A 1B1, Canada.
Plant J. 2011 Oct;68(2):234-48. doi: 10.1111/j.1365-313X.2011.04681.x. Epub 2011 Jul 26.
Cytokinesis and cell polarity are supported by membrane trafficking from the trans-Golgi network (TGN), but the molecular mechanisms that promote membrane trafficking from the TGN are poorly defined in plant cells. Here we show that TRAPPII in Arabidopsis regulates the post-Golgi trafficking that is crucial for assembly of the cell plate and cell polarity. Disruptions of AtTRS120 or AtTRS130, two genes encoding two key subunits of TRAPPII, result in defective cytokinesis and cell polarity in embryogenesis and seedling development. In attrs120 and attrs130, the organization and trafficking in the endoplasmic reticulum (ER)-Golgi interface are normal. However, post-Golgi trafficking to the cell plate and to the cell wall, but not to the vacuole, is impaired. Furthermore, TRAPPII is required for the selective transport of PIN2, but not PIN1, to the plasma membrane. We revealed that AtTRS130 is co-localized with RAB-A1c. Expression of constitutively active RAB-A1c partially rescues attrs130. RAB-A1c, which resides at the TGN, is delocalized to the cytosol in attrs130. We propose that TRAPPII in Arabidopsis acts upstream of Rab-A GTPases in post-Golgi membrane trafficking in plant cells.
细胞分裂和细胞极性是由从高尔基体反面管网（TGN）的膜运输支持的，但在植物细胞中，促进 TGN 膜运输的分子机制还未被很好地定义。在这里，我们表明拟南芥中的 TRAPPII 调节着在后高尔基体运输，这对于细胞板的组装和细胞极性至关重要。AtTRS120 或 AtTRS130 的破坏，这两个基因编码 TRAPPII 的两个关键亚基，导致胚胎发生和幼苗发育中的细胞分裂和细胞极性缺陷。在 attrs120 和 attrs130 中，内质网（ER）-高尔基体界面的组织和运输是正常的。然而，到细胞板和细胞壁的后高尔基体运输，而不是到液泡的运输受损。此外，TRAPPII 是 PIN2 但不是 PIN1 选择性运输到质膜所必需的。我们揭示了 AtTRS130 与 RAB-A1c 共定位。组成型活性 RAB-A1c 的表达部分挽救了 attrs130。RAB-A1c 位于 TGN 中，在 attrs130 中定位于细胞质。我们提出，拟南芥中的 TRAPPII 在植物细胞的高尔基后膜运输中，在上游作用于 Rab-A GTPases。
