| First Author | Dequidt C | Year | 2007 |
| Journal | Mol Biol Cell | Volume | 18 |
| Issue | 8 | Pages | 3131-43 |
| PubMed ID | 17538021 | Mgi Jnum | J:128332 |
| Mgi Id | MGI:3766713 | Doi | 10.1091/mbc.E06-12-1101 |
| Citation | Dequidt C, et al. (2007) Fast turnover of L1 adhesions in neuronal growth cones involving both surface diffusion and exo/endocytosis of L1 molecules. Mol Biol Cell 18(8):3131-43 |
| abstractText | We investigated the interplay between surface trafficking and binding dynamics of the immunoglobulin cell adhesion molecule L1 at neuronal growth cones. Primary neurons were transfected with L1 constructs bearing thrombin-cleavable green fluorescent protein (GFP), allowing visualization of newly exocytosed L1 or labeling of membrane L1 molecules by Quantum dots. Intracellular L1-GFP vesicles showed preferential centrifugal motion, whereas surface L1-GFP diffused randomly, revealing two pathways to address L1 to adhesive sites. We triggered L1 adhesions using microspheres coated with L1-Fc protein or anti-L1 antibodies, manipulated by optical tweezers. Microspheres coupled to the actin retrograde flow at the growth cone periphery while recruiting L1-GFP molecules, of which 50% relied on exocytosis. Fluorescence recovery after photobleaching experiments revealed a rapid recycling of L1-GFP molecules at L1-Fc (but not anti-L1) bead contacts, attributed to a high lability of L1-L1 bonds at equilibrium. L1-GFP molecules truncated in the intracellular tail as well as neuronal cell adhesion molecules (NrCAMs) missing the clathrin adaptor binding sequence showed both little internalization and reduced turnover rates, indicating a role of endocytosis in the recycling of mature L1 contacts at the base of the growth cone. Thus, unlike for other molecules such as NrCAM or N-cadherin, diffusion/trapping and exo/endocytosis events cooperate to allow the fast renewal of L1 adhesions. |
