Endocytic recycling is critical for many cellular events, including the recycling of important nutrient receptors, such as the transferrin receptor and the low-density lipoprotein receptor, for reiterative rounds of ligand uptake, and also the redistribution of integrins from the retracting edges to the leading edge of cells to mediate their motility. Despite these many documented important roles, how proteins are sorted during endocytic recycling, a process that critically regulates their function remains poorly understood. In preliminary studies, we have identified ACAP1 to function in the sorting of cargo proteins that exemplify constitutive and regulated recycling at the recycling endosome, with its phosphorylation providing an explanation for how it is able to participate in both processes. Moreover, we have found that overexpression of ACAP1 induces the coating of endosomes. Thus, in Aim 1, we will provide a more definitive test for whether ACAP1 functions as a coat protein using a reconstitution system that generates transport carriers from the recycling endosome, followed by approaches which will either prove that ACAP1 alone functions as a coat protein or that it functions in conjunction with other proteins as part of coat complex.
In Aim 2, because the critical nexus in regulated transport involves the signaling process interfacing with the transport process, we will identify kinase(s) predicted to directly phosphorylate ACAP1.
In Aim 3, as we have identified sorting signals recognized by ACAP1 for constitutive recycling, we will also identify sorting signal(s) recognized by ACAP1 for regulated recycling, using integrin beta1 as the model system. This finding will then enable us to further elucidate how ACAP1 is able to participate in both constitutive and regulated recycling. Moreover, the identification of recycling sorting signal(s) in integrin beta1 will allow us to test more definitively whether integrin recycling plays a critical role in cell migration, and thereby demonstrating that a better understanding of endocytic recycling has important implications to understanding other cellular events.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM073016-03
Application #
7280848
Study Section
Cell Structure and Function (CSF)
Program Officer
Shapiro, Bert I
Project Start
2005-09-01
Project End
2009-08-31
Budget Start
2007-09-01
Budget End
2008-08-31
Support Year
3
Fiscal Year
2007
Total Cost
$298,678
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
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