studies on the membrane structure remodeling mechanism in early stage of cell plate formation

Abstract

Cytokinesis is the essential process of cell division to partition the cytoplasm of dividing eukatyotic cell to form two daughter cells. Interestingly, plants newly generate plant specific extracellular compartment (called the cell plate) within the cell during cytokinesis. Plants use trans-Golgi network-derived vesicles as building blocks of the cell plate. They accumulate at the center of dividing cells and undergo various structural changes to give rise to the planar cell plate. However, it remains elusive how the conversion of vesicles to the cell plate occurs at the molecular level during cytokinesis. This study reports that SH3 domain-containing protein 2 (SH3P2) in Arabidopsis plays a crucial role in the conversion of vesicles to the planar cell plate. SH3P2 RNAi plants showed cytokinesis-defective phenotypes and produced aggregations of vesicles at the newly formed region of the cell plate. SH3P2 localized to the newly formed region of the cell plate, in particular on the constricted or curved regions of the cell plate. The N-terminal coiled-coil region of SH3P2 has BAR domain features; binding and tubulation of vesicles containing various phosphoinositides (PtdInsPs). In addition, SH3P2 formed a complex with DRP1A which is very well known as a key factor for tubulation of vesicles, but cannot do that alone in vivo. Down regulation of SH3P2 by RNAi system affected DRP1A proper accumulation to the cell plate. Based on these results, I propose that SH3P2 functions together with DRP1A to convert the fused vesicles to tubular structures during cytokinesis.