Protein kinase D regulates vesicular transport by phosphorylating and activating phosphatidylinositol-4 kinase III at the Golgi complex (Nat Cell Biol, 2005, 7:880-886)

報告日期: 2006/03/28
報告時間: 17:10/18:00
報告學生: 張曉娟
講評老師: 徐麗君
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Protein kinase D regulates vesicular transport by phosphorylating and activating phosphatidylinositol-4 kinase IIIβ at the Golgi complex

Nature Cell Biology 7:880-886, 2005

SpeakerChang, Hsaio-Chuan          Time2006/03/28 17:10~18:00

CommentatorHsu, Li-Jin, Ph.D.       Room602     

Abstract

Protein kinase D (PKD) is a family of serine/threonine-specific protein kinases consisting three closely related isoforms (PKD1, PKD2, PKD3) and reporte to localized to the cytosol, nucleus, Golgi complex, and plasma membrane1.  PKD is recruited from the cytosol to the trans-Golgi network (TGN) via the interaction of an amino-terminal zinc finger domain with the lipid diacylglycerol (DAG)2. Then, PKD is activated by trimeric G-protein subunits bg2.  PKD is known to regulate the fission of transport carriers from the TGN to the cell surface, but the mechanism by which PKD regulates vesicle fission and its downstream targets are poorly understood.  Previous reports indicate that phosphatidylinositol 4-phosphate (PI(4)P), an significant lipid mediator, is related to vesicular trafficking.  PI(4)P is generated from PI by PI4 kinases (PI4K).  In yeast and mammalian cells, the PI4K is required for Golgi-to-cell-surface transport3.  On this issue, the authors verify that phosphatidylinositol 4-kinases b (PI4Kb) is a physiological PKD substrate.  Further, the results of the lipid-kinase activity assay and PKD in vitro protein-kinase assay indicate that PI4KIIIβ is phosphorylated at Ser 294 by PKD1 and PKD2, but not PKD3.  And then, the phosphorylation increase the lipid-kinase activity of the PI4Kb.  Depended on those finding, they propose that PKD could regulate secretory transport processes by phosphorylating a set of proteins, including PI4 Kb, and involve in the generation and/or fission of transport vesicles.  Finally, the trafficking from the TGN requires the combined action of proteins and lipid kinases.

Reference

1. Van Lint, J. et al. Trends Cell Biol. 12, 193–200 (2002).

2. Diaz Anel, A. M. & Malhotra, V. J. Cell Biol. 169, 83–91 (2005).

3. Walch-Solimena, C. & Novick, P. The yeast phosphatidylinositol-4-OH kinase

pik1 regulates secretion at the Golgi. Nature Cell Biol. 1, 523–525 (1999).