Intracellular transport is ubiquitous in animal cells and has fundamental importance for diverse biological phenomena, such as secretion, neuronal signaling, organization of endomembranes, and mitosis. The driving force for intracellular transport is provided by molecular motors bound to the surface of cargo organelles and moving along microtubules (MTs) and actin filaments (AFs). Transport of specific organelles is generally driven by several types of molecular motors simultaneously bound to their surface. Furthermore, the same cargo often uses both types of cytoskeletal tracks for the movement. This remarkable complexity of transport mechanisms requires precise regulation to ensure delivery to specific cellular destinations. Here, we propose to examine the mechanisms of regulation of intracellular transport using Xenopus melanophores as an experimental system. The major function of these cells is fast and synchronous redistribution of thousands of membrane-bounded pigment granules, which aggregate in the cell center or uniformly disperse throughout the cytoplasm by moving along MTs and AFs by means of cytoplasmic dynein (aggregation), and kinesin-2 and myosin Va (dispersion). Switching between these motors and cytoskeletal systems is regulated by a single second messenger, cAMP, and involves the activity of Protein Kinase A (PKA). Background data by the PI indicate that changes in properties of MTs and AFs may play active role in regulation of pigment granule transport. Preliminary data also indicate that PKA is bound to pigment granules where it forms complexes with molecular motors that may include other protein kinases and phosphatases regulating motor activities. This proposal will use a combination of molecular, cellular, and biochemical approaches to test the hypothesis that aggregation and dispersion signals control redistribution of pigment granules through cooperation of two interdependent mechanisms, regulation cytoskeletal tracks that provide rails for the movement, and molecular motors that generate force for transport.
Specific Aims of this grant application are: (1) To test the hypothesis that transport of pigment granules is regulated by changes in availability and transport properties of MT and AF tracks; (2) To test the hypothesis that regulation of pigment granule motility involves localized signaling molecules bound to pigment granules that form complexes with molecular motors and control their activities.
Understanding the mechanisms that mediate and control intracellular transport is essential for the elucidation of molecular basis of diseases that involve intracellular transport defects. The long-term goal of research outlined in this proposal is to develop new therapeutic strategies aimed at prevention and treatment of intracellular transport disorders.
|Deb Roy, Abhijit; Yin, Taofei; Choudhary, Shilpa et al. (2017) Optogenetic activation of Plexin-B1 reveals contact repulsion between osteoclasts and osteoblasts. Nat Commun 8:15831|
|Marchenko, Olena O; Das, Sulagna; Yu, Ji et al. (2017) A minimal actomyosin-based model predicts the dynamics of filopodia on neuronal dendrites. Mol Biol Cell 28:1021-1033|
|Semenova, Irina; Gupta, Dipika; Usui, Takeo et al. (2017) Stimulation of microtubule-based transport by nucleation of microtubules on pigment granules. Mol Biol Cell 28:1418-1425|
|Rezaul, Karim; Gupta, Dipika; Semenova, Irina et al. (2016) Engineered Tug-of-War Between Kinesin and Dynein Controls Direction of Microtubule Based Transport In Vivo. Traffic 17:475-86|
|Osunbayo, Olaolu; Butterfield, Jacqualine; Bergman, Jared et al. (2015) Cargo transport at microtubule crossings: evidence for prolonged tug-of-war between kinesin motors. Biophys J 108:1480-3|
|Semenova, Irina; Ikeda, Kazuho; Resaul, Karim et al. (2014) Regulation of microtubule-based transport by MAP4. Mol Biol Cell 25:3119-32|
|Denton, Kyle R; Lei, Ling; Grenier, Jeremy et al. (2014) Loss of spastin function results in disease-specific axonal defects in human pluripotent stem cell-based models of hereditary spastic paraplegia. Stem Cells 32:414-23|
|Schroeder 3rd, Harry W; Hendricks, Adam G; Ikeda, Kazuho et al. (2012) Force-dependent detachment of kinesin-2 biases track switching at cytoskeletal filament intersections. Biophys J 103:48-58|
|Lomakin, Alexis J; Kraikivski, Pavel; Semenova, Irina et al. (2011) Stimulation of the CLIP-170--dependent capture of membrane organelles by microtubules through fine tuning of microtubule assembly dynamics. Mol Biol Cell 22:4029-37|
|Ikeda, Kazuho; Zhapparova, Olga; Brodsky, Ilya et al. (2011) CK1 activates minus-end-directed transport of membrane organelles along microtubules. Mol Biol Cell 22:1321-9|
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