title: Amotl2 interacts with LL5β, localizes to podosomes and regulates postsynaptic differentiation in muscle.
abstract: Neuromuscular junctions (NMJs) in mammalian skeletal muscle undergo a postnatal topological transformation from a simple oval plaque to a complex branched structure. We previously showed that podosomes, actin-rich adhesive organelles, promote the remodeling process, and demonstrated a key role for one podosome component, LL5β. To further investigate molecular mechanisms of postsynaptic maturation, we purified LL5β-associated proteins from myotubes and showed that three regulators of the actin cytoskeleton--Amotl2, Asef2 and Flii--interact with LL5β. These and other LL5β-interacting proteins are associated with conventional podosomes in macrophages and podosome-like invadopodia in fibroblasts, strengthening the close relationship between synaptic and non-synaptic podosomes. We then focused on Amotl2, showing that it is associated with synaptic podosomes in cultured myotubes and with NMJs in vivo. Depletion of Amotl2 in myotubes leads to increased size of synaptic podosomes and corresponding alterations in postsynaptic topology. Depletion of Amotl2 from fibroblasts disrupts invadopodia in these cells. These results demonstrate a role for Amotl2 in synaptic maturation and support the involvement of podosomes in this process.
authors.affiliation: Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Tomasz J
authors.initials: TJ
authors.lastname: Proszynski
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Sanes
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D022081:Cell Surface Extensions / Q000648:ultrastructure; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D032446:Myoblasts / Q000502:physiology* / Q000648:ultrastructure; D009469:Neuromuscular Junction; D011485:Protein Binding; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D055366:Synaptic Potentials; D015534:Trans-Activators
chemical_list: D002352:Carrier Proteins; C098179:FLII protein, human; D020662:Guanine Nucleotide Exchange Factors; D008840:Microfilament Proteins; C471180:PHLDB2 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; C525704:SPATA13 protein, human; D015534:Trans-Activators
keywords: Acetylcholine receptor; Neuromuscular junction; Podosome