Synaptic adhesion-like molecules (SALMs) promote neurite outgrowth.
SALMs are a family of five adhesion molecules whose expression is largely restricted to the CNS. Initial reports showed that SALM1 functions in neurite outgrowth while SALM2 is involved in synapse formation. To investigate the function of SALMs in detail, we asked if all five are involved in neurite outgrowth. Expression of epitope-tagged proteins in cultured hippocampal neurons showed that SALMs are distributed throughout neurons, including axons, dendrites, and growth cones. Over-expression of each SALM resulted in enhanced neurite outgrowth, but with different phenotypes. Neurite outgrowth could be reduced by applying antibodies targeting the extracellular leucine rich regions of SALMs and with RNAi. Through over-expression of deletion constructs, we found that the C-terminal PDZ binding domains of SALMs 1-3 are required for most aspects of neurite outgrowth. In addition, by using a chimera of SALMs 2 and 4, we found that the N-terminus is also involved in neurite outgrowth.
Wang
Philip Y
PY
Laboratory of Neurochemistry, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
Seabold
Gail K
GK
Wenthold
Robert J
RJ
D000818:Animals; D000906:Antibodies / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D006624:Hippocampus / Q000166:cytology; D016501:Neurites / Q000378:metabolism* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure
D000906:Antibodies; D015816:Cell Adhesion Molecules, Neuronal; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins