Structure and function of primitive immunoglobulin superfamily neural cell adhesion molecules: a lesson from studies on planarian.
Precise wiring and proper remodeling of the neural network are essential for its normal function. The freshwater planarian is an attractive animal in which to study the formation and maintenance of the neural network due to its high regenerative capability and developmental plasticity. Although a recent study revealed that homologs of netrin and its receptors are required for regeneration and maintenance of the planarian central nervous system (CNS), the roles of cell adhesion in the formation and maintenance of the planarian neural network remain poorly understood. In the present study, we found primitive immunoglobulin superfamily cell adhesion molecules (IgCAMs) in a planarian that are homologous to vertebrate neural IgCAMs. We identified planarian orthologs of NCAM, L1CAM, contactin and DSCAM, and designated them DjCAM, DjLCAM, DjCTCAM and DjDSCAM, respectively. We further confirmed that they function as cell adhesion molecules using cell aggregation assays. DjCAM and DjDSCAM were found to be differentially expressed in the CNS. Functional analyses using RNA interference revealed that DjCAM is partly involved in axon formation, and that DjDSCAM plays crucial roles in neuronal cell migration, axon outgrowth, fasciculation and projection.
Fusaoka
Eri
E
Department of Biological Science, Nagoya University Graduate School of Science, Furocho, Chikusa-ku, Nagoya 464-8602, Japan.
Inoue
Takeshi
T
Mineta
Katsuhiko
K
Agata
Kiyokazu
K
Takeuchi
Kosei
K
D000818:Animals; D001369:Axons / Q000502:physiology; D001921:Brain / Q000502:physiology; D015815:Cell Adhesion Molecules; D002490:Central Nervous System / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D007136:Immunoglobulins / Q000737:chemistry*; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D008807:Mice, Inbred BALB C; D008957:Models, Genetic; D009043:Motor Activity; D009415:Nerve Net / Q000502:physiology; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry* / Q000502:physiology*; D010802:Phylogeny; D010932:Planarians / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D011506:Proteins / Q000235:genetics / Q000502:physiology; D034622:RNA Interference; D012038:Regeneration; D013329:Structure-Activity Relationship
D015815:Cell Adhesion Molecules; C491735:Dscam protein, mouse; D007136:Immunoglobulins; D019006:Neural Cell Adhesion Molecules; D011506:Proteins