Hotspots Organize Clathrin-Mediated Endocytosis by Efficient Recruitment and Retention of Nucleating Resources

Daniel Nunez, Costin Antonescu, Marcel Mettlen, Allen Liu, Sandra L. Schmid, Dinah Loerke, Gaudenz Danuser

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

The formation of clathrin-coated pits (CCPs) at the plasma membrane has been reported to sometimes occur repeatedly at predefined sites. However, defining such CCP 'hotspots' structurally and mechanistically has been difficult due to the dynamic and heterogeneous nature of CCPs. Here, we explore the molecular requirements for hotspots using a global assay of CCP dynamics. Our data confirmed that a subset of CCPs is nucleated at spatially distinct sites. The degree of clustering of nucleation events at these sites is dependent on the integrity of cortical actin, and the availability of certain resources, including the adaptor protein AP-2 and the phospholipid PI(4,5)P 2. We observe that modulation in the expression level of FCHo1 and 2, which have been reported to initiate CCPs, affects only the number of nucleations. Modulation in the expression levels of other accessory proteins, such as SNX9, affects the spatial clustering of CCPs but not the number of nucleations. On the basis of these findings, we distinguish two classes of accessory proteins in clathrin-mediated endocytosis (CME): nucleation factors and nucleation organizers. Finally, we observe that clustering of transferrin receptors spatially randomizes pit nucleation and thus reduces the role of hotspots. On the basis of these data, we propose that hotspots are specialized cortical actin patches that organize CCP nucleations from within the cell by more efficient recruitment and/or retention of the resources required for CCP nucleation partially due to the action of nucleation organizers.

Original languageEnglish (US)
Pages (from-to)1868-1878
Number of pages11
JournalTraffic
Volume12
Issue number12
DOIs
StatePublished - Dec 2011

Keywords

  • Clathrin
  • Endocytosis
  • FCHo1
  • FCHo2
  • Hotspot
  • SNX9

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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