"Phosphoinositides across the cell landscape: from endocytosis to vascular differentiation"

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Thursday 15 February 2018, 11:00 - 12:30

 
ABSTRACT

Bojan Gujas, Tiago M.D.Cruz, Elizabeth Kastanaki, Joop E.M. Vermeer, Teun Munnik  and Antia Rodriguez-Villalon1.

In multicellular organisms, differentiation programs involve drastic changes in cell size, morphology and signal responsiveness to acquire specialized functional features. A fascinating example of this process is the differentiation of plant vascular cells in conducting elements. In vascular plants, the phloem is a living tissue transporting organic nutrients throughout the plant, whereas the xylem is mainly composed of dead cells required for the delivery of water and nutrients to the above-ground organs. To become functional units, phloem and xylem cells undergo two different morphogenetic developmental programs which involve the reinforcement of their cell wall and total or partial cell clearance. Interestingly, our results show that a genetic disturbance of the phosphoinositide homeostasis at the plasma membrane (PM) antagonistically impinge on both vascular programs. In particular, an increase of phosphatidylinositol 4,5-bis-phosphate [PtdIns(4,5)P2] rewires intracellular trafficking towards the vacuole in Arabidopsis thaliana root cells. Consequently, an enhanced phosphoinositide-mediated vacuolar biogenesis leads to premature PCD and secondary cell wall building in xylem cells. Inhibition of vesicular trafficking from trans-Golgi network (TGN) to the vacuole by brefeldin A (BFA) application abolishes the premature xylem differentiation triggered by increasing PtdIns(4,5)P2 levels. On the contrary, BFA treatments induces the abnormal formation of big vacuoles in mature protophloem cells, preventing cell clearance and thus, tissue functionality. Together, our data indicate that a tight PM phosphoinositide homeostasis is required to modulate vacuolar biogenesis, contributing to antagonistically regulate vascular cell differentiation.

Location Jozef Schell Seminar Room
Contact Assistant Prof Antia Rodriguez-Villalon
ETH-Zürich
SWITZERLAND