Extension of the endoplasmic reticulum (ER) into dendritic spines of Purkinje neurons (PNs) is required for cerebellar synaptic plasticity and is disrupted in animals with null mutations in Myo5a, the gene encoding myosin-Va1-3. While it has been proposed that animal class V myosins localize organelles by tethering them to the actin cytoskeleton4-7, we demonstrate here that myosin-Va acts as a point-to-point organelle transporter to pull ER as cargo into PN spines. Specifically, the myosin accumulates at the ER tip as the organelle moves into spines, and the myosins ability to hydrolyze ATP is required for spine ER targeting. Moreover, myosin-Va is responsible for the vast majority of spine ER insertional events. Finally, attenuation of the myosins ability to move along actin filaments reduces the maximum velocity of ER movement into spines, providing direct evidence that myosin-Va drives ER motility. Thus, we establish that an actin-based motor moves ER within animal cells, and we uncover the mechanism that mediates ER localization to PN spines, a prerequisite for synaptic plasticity.

Project Start
Project End
Budget Start
Budget End
Support Year
28
Fiscal Year
2011
Total Cost
$625,128
Indirect Cost
Name
National Heart, Lung, and Blood Institute
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Type
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Beach, Jordan R; Bruun, Kyle S; Shao, Lin et al. (2017) Actin dynamics and competition for myosin monomer govern the sequential amplification of myosin filaments. Nat Cell Biol 19:85-93
Bruun, Kyle; Beach, Jordan R; Heissler, Sarah M et al. (2017) Re-evaluating the roles of myosin 18A? and F-actin in determining Golgi morphology. Cytoskeleton (Hoboken) 74:205-218
Varadarajan, Ramya; Hammer, John A; Rusan, Nasser M (2017) A centrosomal scaffold shows some self-control. J Biol Chem 292:20410-20411
Beach, Jordan R; Hammer 3rd, John A (2015) Myosin II isoform co-assembly and differential regulation in mammalian systems. Exp Cell Res 334:2-9
Li, Dong; Shao, Lin; Chen, Bi-Chang et al. (2015) ADVANCED IMAGING. Extended-resolution structured illumination imaging of endocytic and cytoskeletal dynamics. Science 349:aab3500
Billington, Neil; Beach, Jordan R; Heissler, Sarah M et al. (2015) Myosin 18A coassembles with nonmuscle myosin 2 to form mixed bipolar filaments. Curr Biol 25:942-8
Beach, Jordan R; Shao, Lin; Remmert, Kirsten et al. (2014) Nonmuscle myosin II isoforms coassemble in living cells. Curr Biol 24:1160-6
Chen, Bi-Chang; Legant, Wesley R; Wang, Kai et al. (2014) Lattice light-sheet microscopy: imaging molecules to embryos at high spatiotemporal resolution. Science 346:1257998
Hammer 3rd, John A; Wagner, Wolfgang (2013) Functions of Class V Myosins in Neurons. J Biol Chem :
Hammer 3rd, John A; Burkhardt, Janis K (2013) Controversy and consensus regarding myosin II function at the immunological synapse. Curr Opin Immunol 25:300-6

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