Clathrin-mediated endocytosis (CME) is a major route by which cells take up many nutrients and regulatory molecules and down-regulate membrane proteins in response to their ligands and environmental signals. Further importance of this pathway is exemplified by a number of human diseases that are associated with CME, including cancer, cardiovascular and neurological disorders, and entry of infectious viruses into cells. While many factors involved in CME have been identified and a large number of protein- protein or protein-lipid interactions for them have been described, assigning specific roles to these proteins remains a challenge to the field. There is still much to learn about how cargo are collected, the importance of the elaborate network of interactions and scaffolding functions of the endocytic machinery, how force is generated to invaginate and pinch off a vesicle, and how the timing and regulation of assembly and disassembly of these components coordinates this dynamic process. Moreover, aside from phosphoinositides, little is known about lipid requirements for formation of an endocytic vesicle. Studies in this lab have combined live cell imaging analysis with biochemistry, cell biology and the powerful molecular genetics methods of S. cerevisiae to study the endocytic process. In yeast, as in all eukaryotes, both clathrin and the actin cytoskeleton are critical for endocytosis. Furthermore, most endocytic factors identified in yeast have conserved counterparts in animal cells that are involved in CME. Work from several labs, including ours, has clearly validated yeast as an important model for discovering how this large "molecular machine" drives the internalization process. In this project we continue our efforts to dissect the roles of components of the endocytic machinery using the yeast system. We focus primarily on the novel F-BAR family of FCHO1/2 proteins (Syp1 in yeast), the role of clathrin light chain and regulation of its binding partner Sla2 (related to Hip1/R proteins in animl cells), and the roles of lipids in generating an endocytic vesicle. These studies will provide new insight into the mechanisms of endocytosis and vesicle formation during membrane transport in general.

Public Health Relevance

Clathrin mediated endocytosis is a principal pathway for internalization of many important cellular components, such as lipids, iron, immunoglobulins, many receptors, and viruses. It plays a key role in cell communication, hormone regulation, cell polarity, immune response, growth and development. Therefore, unraveling the roles of the many components involved in endocytosis, including the membrane lipid composition needed, has relevance for diverse human diseases, including cancer, diabetes, cardiovascular disease, neurological disorders, and bacterial and viral infection.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01GM055796-16
Application #
8706888
Study Section
Membrane Biology and Protein Processing Study Section (MBPP)
Program Officer
Ainsztein, Alexandra M
Project Start
Project End
Budget Start
Budget End
Support Year
16
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Miami School of Medicine
Department
Pharmacology
Type
Schools of Medicine
DUNS #
City
Coral Gables
State
FL
Country
United States
Zip Code
33146
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Boettner, Douglas R; Chi, Richard J; Lemmon, Sandra K (2012) Lessons from yeast for clathrin-mediated endocytosis. Nat Cell Biol 14:2-10
Boettner, Douglas R; Friesen, Helena; Andrews, Brenda et al. (2011) Clathrin light chain directs endocytosis by influencing the binding of the yeast Hip1R homologue, Sla2, to F-actin. Mol Biol Cell 22:3699-714
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Newpher, Thomas M; Smith, Robin P; Lemmon, Vance et al. (2005) In vivo dynamics of clathrin and its adaptor-dependent recruitment to the actin-based endocytic machinery in yeast. Dev Cell 9:87-98
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