Molecular motor proteins operate in a complex and crowded cellular environment. Microtubules in the cell are coated with microtubule-associated proteins (MAPs) and serve as tracks for the simultaneous movement of many types of organelles and vesicles. In addition, many critical cellular processes such as endocytosis involve the regulated switching of transport organelles from one type of cytoskeletal filament to another. During endocytosis, vesicles make a directed switch from movement along cortical actin filaments to centripetal movement along microtubules toward the cell center. Initial in vitro systems to analyze motor function have involved the study of single motor types moving along """"""""naked"""""""" filaments polymerized from purified actin or tubulin subunits. However, in vitro studies using increasingly more complex models will provide insights that more clearly address the cellular situation. Here, we propose to build on recent data demonstrating that motors are differentially affected by obstacles in their paths, such as MAPs or intersecting filaments. We will compare motor function at the single molecule level and also in the context of endogenous cellular cargos such as purified endocytic vesicles. Specifically, we propose the following three aims: (1) To investigate the effects of microtubule associated proteins (MAPs) on the motility of the microtubule motors kinesin and dynein functioning either individually or in concert on purified vesicles and organelles. Can microtubule-associated proteins provide spatially-specific regulation of motor function in the cell? (2) To examine the interactions of multiple motor proteins, including both actin-based and microtubule-based motors bound to cargos moving on arrays composed of intersecting actin filaments and microtubules, to examine the parameters associated with track switching. Is filament switching a regulated or a stochastic process in the cell? And (3) To compare these in vitro observations with cellular studies examining motor function during receptor-mediated endocytosis with three-dimensional, high resolution fluorescence imaging coupled to EM analysis to obtain spatial and temporal information on filament switching in the cell. Together, these studies will provide new insights into motor integration and coordination during intracelllular transport.

Public Health Relevance

Microtubule-based and actin-based transport are required for normal function in the eukaryotic cell, and defects in these processes result in both developmental and degenerative diseases. Here, we will develop in vitro assays that more accurately model the intracellular environment in order to examine the parameters of intracellular motility, and we will compare these in vitro data with high resolution studies of trafficking in the cell to improve our understanding of intracellular dynamics.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Program Projects (P01)
Project #
5P01GM087253-08
Application #
8242092
Study Section
Special Emphasis Panel (ZRG1)
Project Start
Project End
Budget Start
2011-04-01
Budget End
2012-03-31
Support Year
8
Fiscal Year
2011
Total Cost
$318,571
Indirect Cost
Name
University of Pennsylvania
Department
Type
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
McIntosh, Betsy B; Pyrpassopoulos, Serapion; Holzbaur, Erika L F et al. (2018) Opposing Kinesin and Myosin-I Motors Drive Membrane Deformation and Tubulation along Engineered Cytoskeletal Networks. Curr Biol 28:236-248.e5
Moore, Andrew S; Holzbaur, Erika L F (2018) Mitochondrial-cytoskeletal interactions: dynamic associations that facilitate network function and remodeling. Curr Opin Physiol 3:94-100
Woody, Michael S; Capitanio, Marco; Ostap, E Michael et al. (2018) Electro-optic deflectors deliver advantages over acousto-optical deflectors in a high resolution, ultra-fast force-clamp optical trap. Opt Express 26:11181-11193
Lee, In-Gyun; Olenick, Mara A; Boczkowska, Malgorzata et al. (2018) A conserved interaction of the dynein light intermediate chain with dynein-dynactin effectors necessary for processivity. Nat Commun 9:986
Lippert, Lisa G; Dadosh, Tali; Hadden, Jodi A et al. (2017) Angular measurements of the dynein ring reveal a stepping mechanism dependent on a flexible stalk. Proc Natl Acad Sci U S A 114:E4564-E4573
Pyrpassopoulos, Serapion; Shuman, Henry; Ostap, E Michael (2017) Adhesion force and attachment lifetime of the KIF16B-PX domain interaction with lipid membranes. Mol Biol Cell 28:3315-3322
Lewis, John H; Jamiolkowski, Ryan M; Woody, Michael S et al. (2017) Deconvolution of Camera Instrument Response Functions. Biophys J 112:1214-1220
Greenberg, Michael J; Shuman, Henry; Ostap, E Michael (2017) Measuring the Kinetic and Mechanical Properties of Non-processive Myosins Using Optical Tweezers. Methods Mol Biol 1486:483-509
Hendricks, Adam G; Goldman, Yale E (2017) Measuring Molecular Forces Using Calibrated Optical Tweezers in Living Cells. Methods Mol Biol 1486:537-552
Kast, David J; Dominguez, Roberto (2017) The Cytoskeleton-Autophagy Connection. Curr Biol 27:R318-R326

Showing the most recent 10 out of 42 publications