title: Polarization of actin cytoskeleton is reduced in dendritic protrusions during early spine development in hippocampal neuron.
abstract: Dendritic spines are small protrusions that receive synaptic signals in neuronal networks. The actin cytoskeleton plays a key role in regulating spine morphogenesis, as well as in the function of synapses. Here we report the first quantitative measurement of F-actin retrograde flow rate in dendritic filopodia, the precursor of dendritic spines, and in newly formed spines, using a technique based on photoactivation localization microscopy. We found a fast F-actin retrograde flow in the dendritic filopodia but not in the spine necks. The quantification of F-actin flow rates, combined with fluorescence recovery after photobleaching measurements, allowed for a full quantification of spatially resolved kinetic rates of actin turnover, which was not previously feasible. Furthermore we provide evidences that myosin II regulates the actin flow in dendritic filopodia and translocates from the base to the tip of the protrusion upon spine formation. Rac1 inhibition led to mislocalization of myosin II, as well as to disruption of the F-actin flow. These results provide advances in the quantitative understanding of F-actin remodeling during spine formation.
authors: Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06030, USA.
authors: Vedakumar
authors: V
authors: Tatavarty
authors: Sulagna
authors: S
authors: Das
authors: Ji
authors: J
authors: Yu
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000465:Algorithms; D000818:Animals; D002465:Cell Movement; D049229:Dendritic Spines / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D036681:Fluorescence Recovery After Photobleaching; D006624:Hippocampus / Q000166:cytology*; D007700:Kinetics; D008856:Microscopy, Fluorescence; D024462:Myosin Type II / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D010446:Peptide Fragments; D058105:Polymerization; D055503:Protein Multimerization; D021381:Protein Transport; D011554:Pseudopodia / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D059008:Time-Lapse Imaging; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; D010446:Peptide Fragments; C403751:Rac1 GTP-binding protein (17-32); D024462:Myosin Type II; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein