期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 103, 期 51, 页码 19332-19337出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0609795104
关键词
dynamin; endocytosis; endophilin; phosphoinositides; phosphatidylinositol (4,5)-bisphosphate
资金
- NCI NIH HHS [P01 CA046128, CA46128] Funding Source: Medline
- NIDA NIH HHS [DA018343, P30 DA018343] Funding Source: Medline
- NIDDK NIH HHS [P30 DK045735, DK45735] Funding Source: Medline
- NINDS NIH HHS [NS36251, R37 NS036251, R01 NS036251] Funding Source: Medline
Phosphoinositides are thought to play an important role in clathrin-coated pit (CCP) dynamics. Biochemical and structural studies have shown a direct interaction of phosphatidylinositol (4,5)bisphosphate [PI(4,5)P-2] with endocytic clathrin adaptors, whereas functional studies using cell-free systems or intact cells have demonstrated the importance of PI(4,5)P2 synthesis and dephosphorylation in clathrin coating and uncoating, respectively. Furthermore, genetic manipulations of kinases and phosphatases involved in PI(4,5)P2 metabolism result in major defects in synaptic vesicle recycling and other forms of clathrin-dependent endocytosis. However, live imaging studies of these enzymes at CCPs have not been conducted. We have used multicolor total internal reflection fluorescence microscopy (TIRFM) to visualize the spatial-temporal recruitment of synaptojanin 1 (SJ1), a polyphosphoinositide phosphatase, and its binding partner enclophilin to CCPs. Strikingly, we observed differential temporal recruitment of the two major SJ1 splice variants to CCPs. The 145-kDa isoform, the predominant isoform expressed in the brain, was rapidly recruited as a burst, together with enclophilin, at a late stage of CCP formation. In contrast, the nonneuronal ubiquitously expressed 170-kDa isoform of SJ1 was present at all stages of CCP formation. These results raise the possibility that dynamic phosphoinositide metabolism may occur throughout the lifetime of a CCP.
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