AlphaII-spectrin participates in the surface expression of cell adhesion molecule L1 and neurite outgrowth.
AlphaII-spectrin, a basic component of the spectrin-based scaffold which organizes and stabilizes membrane microdomains in most animal cells, has been recently implicated in cell adherence and actin dynamics. Here we investigated the contribution of αΙΙ-spectrin to neuritogenesis, a highly complex cellular process which requires continuous actin cytoskeleton remodeling and cross-talk between extracellular cues and their cell surface receptors, including cell adhesion molecules. Using RNA interference-mediated gene silencing to down-regulate αΙΙ-spectrin expression in human neuroblastoma SH-SY5Y cells, we observed major changes in neurite morphology and cell shape: (1) reduced mean length and a higher number of neurites per cell; occasional long neurites were thinner and displayed abnormal adhesiveness during cell migration resulting in frequent breaks; similar persisting adhesiveness and breaks were also observed in trailing edges of cell bodies; (2) irregular polygonal cell shape in parallel with loss of cortical F-actin from neuronal cell bodies; (3) reduction in protein levels of αΙ- and βΙ-spectrins, but not βΙΙ-spectrin (4) decreased global expression of adhesion molecule L1 and spectrin-binding adapter ankyrin-B, which links L1 to the plasma membrane. Remarkably, αΙΙ-spectrin depletion affected L1 - but not NCAM - cell surface expression, and L1 clustering at growth cones. This study demonstrates that αΙΙ-spectrin is implicated in normal morphology and adhesive properties of neuron cell bodies and neurites, and in cell surface expression and organization of adhesion molecule L1.
INSERM, U665, F-75015 Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, UMR_S 665, F-75739 Paris, France; Institut National de la Transfusion Sanguine, F-75015 Paris, France.
Marie-Marcelle
MM
Trinh-Trang-Tan
INSERM, U665, F-75015 Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, UMR_S 665, F-75739 Paris, France; Institut National de la Transfusion Sanguine, F-75015 Paris, France.
Sylvain
S
Bigot
INSERM, U665, F-75015 Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, UMR_S 665, F-75739 Paris, France; Institut National de la Transfusion Sanguine, F-75015 Paris, France.
Julien
J
Picot
INSERM, U665, F-75015 Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, UMR_S 665, F-75739 Paris, France; Institut National de la Transfusion Sanguine, F-75015 Paris, France.
Marie-Christine
MC
Lecomte
INSERM, U665, F-75015 Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, UMR_S 665, F-75739 Paris, France; Institut National de la Transfusion Sanguine, F-75015 Paris, France. Electronic address: ekaterini.kordeli@inserm.fr.
Ekaterini
E
Kordeli
D000818:Animals; D017487:Ankyrins / Q000378:metabolism; D015153:Blotting, Western; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism*; D016501:Neurites / Q000502:physiology*; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology*; D034741:RNA, Small Interfering / Q000235:genetics; D013049:Spectrin / Q000378:metabolism; D014407:Tumor Cells, Cultured
D017487:Ankyrins; D002352:Carrier Proteins; D049452:Green Fluorescent Proteins; D008840:Microfilament Proteins; D039842:Neural Cell Adhesion Molecule L1; D034741:RNA, Small Interfering; D013049:Spectrin; C498994:ANK2 protein, human; C452439:SPTBN1 protein, human; C495133:SPTBN2 protein, human
Ankyrin; Filamentous actin; Growth cone; L1; NCAM; Neurite breaks; Neuritogenesis; Spectrin