title: The role of myosin-II in force generation of DRG filopodia and lamellipodia.
abstract: Differentiating neurons process the mechanical stimulus by exerting the protrusive forces through lamellipodia and filopodia. We used optical tweezers, video imaging and immunocytochemistry to analyze the role of non-muscle myosin-II on the protrusive force exerted by lamellipodia and filopodia from developing growth cones (GCs) of isolated Dorsal Root Ganglia (DRG) neurons. When the activity of myosin-II was inhibited by 30 μM Blebbistatin protrusion/retraction cycles of lamellipodia slowed down and during retraction lamellipodia could not lift up axially as in control condition. Inhibition of actin polymerization with 25 nM Cytochalasin-D and of microtubule polymerization with 500 nM Nocodazole slowed down the protrusion/retraction cycles, but only Cytochalasin-D decreased lamellipodia axial motion. The force exerted by lamellipodia treated with Blebbistatin decreased by 50%, but, surprisingly, the force exerted by filopodia increased by 20-50%. The concomitant disruption of microtubules caused by Nocodazole abolished the increase of the force exerted by filopodia treated with Blebbistatin. These results suggest that; i- Myosin-II controls the force exerted by lamellipodia and filopodia; ii- contractions of the actomyosin complex formed by filaments of actin and myosin have an active role in ruffle formation; iii- myosin-II is an essential component of the structural stability of GCs architecture.
authors.affiliation: Neuroscience Area, International School for Advanced Studies (SISSA), IT-34136 Trieste, Italy.
authors.forename: Wasim A
authors.initials: WA
authors.lastname: Sayyad
authors.affiliation: Neuroscience Area, International School for Advanced Studies (SISSA), IT-34136 Trieste, Italy.
authors.forename: Ladan
authors.initials: L
authors.lastname: Amin
authors.affiliation: Neuroscience Area, International School for Advanced Studies (SISSA), IT-34136 Trieste, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Fabris
authors.affiliation: Neuroscience Area, International School for Advanced Studies (SISSA), IT-34136 Trieste, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Ercolini
authors.affiliation: Neuroscience Area, International School for Advanced Studies (SISSA), IT-34136 Trieste, Italy.
authors.forename: Vincent
authors.initials: V
authors.lastname: Torre
mesh_terms: D000818:Animals; D015638:Cytochalasin D / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D018995:Myosin Heavy Chains / Q000378:metabolism; D024462:Myosin Type II / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D015739:Nocodazole / Q000494:pharmacology; D052898:Optical Tweezers; D011554:Pseudopodia / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014404:Tubulin / Q000378:metabolism
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; D014404:Tubulin; C472645:blebbistatin; D015638:Cytochalasin D; D024462:Myosin Type II; D018995:Myosin Heavy Chains; D015739:Nocodazole