1. L1 syndrome mutations impair neuronal L1 function at different levels by divergent mechanisms.
- Author
-
Schäfer MK, Nam YC, Moumen A, Keglowich L, Bouché E, Küffner M, Bock HH, Rathjen FG, Raoul C, and Frotscher M
- Subjects
- Animals, Cell Line, Cell Membrane metabolism, Cell Membrane pathology, Cell Membrane ultrastructure, Cell Polarity genetics, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum pathology, Endoplasmic Reticulum ultrastructure, Humans, Neural Cell Adhesion Molecule L1 physiology, Neurogenesis genetics, Neurons ultrastructure, Organ Culture Techniques, Protein Transport genetics, Rats, Rats, Wistar, Syndrome, CA3 Region, Hippocampal metabolism, CA3 Region, Hippocampal pathology, Mutation genetics, Neural Cell Adhesion Molecule L1 genetics, Neurons metabolism, Neurons pathology
- Abstract
Mutations in the human L1CAM gene cause neurodevelopmental disorders collectively referred to as L1 syndrome. Here, we investigated cellular pathomechanisms underlying two L1 syndrome mutations, R184Q and W1036L. We demonstrate that these mutations cause partial endoplasmic reticulum (ER) retention of L1, reduce L1 cell surface expression, but do not induce ER stress in neuronal NSC-34 cells. We provide evidence that surface trafficking of mutated L1 is affected by defective sorting to ER exit sites and attenuated ER export. However, in differentiated neuronal cultures and long-term cultured hippocampal slices, the L1-R184Q protein is restricted to cell bodies, whereas L1-W1036L also aberrantly localizes to dendrites. These trafficking defects preclude axonal targeting of L1, thereby affecting L1-mediated axon growth and arborization. Our results indicate that L1 syndrome mutations impair neuronal L1 function at different levels, firstly by attenuating ER export and secondly by interfering with polarized neuronal trafficking., ((c) 2010 Elsevier Inc. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF