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In vivo and in vitro Studies of Adaptor-clathrin Interaction
Published on: January 26, 2011
Phosphoinositide-mediated clathrin adaptor progression at the trans-Golgi network
Lydia Daboussi1, Giancarlo Costaguta, Gregory S Payne
1Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA.
Nature Cell Biology
|February 21, 2012
Summary
This study reveals how phosphatidylinositol 4-phosphate (PtdIns(4)P)) regulates clathrin adaptor assembly at the trans-Golgi network (TGN). Sequential recruitment of GGA proteins and AP-1 complexes is controlled by PtdIns(4)P levels, impacting vesicle transport.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Clathrin-coated vesicles are essential for endocytosis and intracellular transport.
- Clathrin adaptors, including GGA proteins and the AP-1 complex, mediate cargo selection and coat assembly at the trans-Golgi network (TGN).
- The sequential recruitment and regulation of these adaptors at the TGN remain incompletely understood.
Purpose of the Study:
- To investigate the relationship and regulation between GGA proteins, AP-1, and other clathrin adaptors at the TGN in yeast.
- To elucidate the role of phosphatidylinositol 4-phosphate (PtdIns(4)P) in the dynamic assembly of clathrin coats.
- To characterize the mechanism governing progressive, adaptor-specific clathrin coat formation at the TGN.
Main Methods:
- Live-cell and super-resolution microscopy in yeast.
- Genetic manipulation of phosphatidylinositol 4-phosphate (PtdIns(4)P) levels.
- Analysis of clathrin adaptor recruitment dynamics.
Main Results:
- GGA proteins and AP-1 are recruited sequentially to the TGN in two distinct waves of coat assembly.
- Reduced PtdIns(4)P levels at the TGN impair or uncouple AP-1 assembly from GGA assembly.
- Enhanced PtdIns(4)P synthesis accelerates the timing between adaptor recruitment waves.
- Gga2p directly interacts with and contributes to the recruitment of the PtdIns(4)P kinase, Pik1p.
Conclusions:
- A PtdIns(4)P-dependent mechanism regulates the progressive and sequential assembly of adaptor-specific clathrin coats at the TGN.
- This study identifies a novel regulatory pathway for clathrin-mediated transport at the TGN, involving direct interactions between adaptors and lipid kinases.
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