Genetic analysis of an overlapping functional requirement for L1- and NCAM-type proteins during sensory axon guidance in Drosophila.
L1- and NCAM-type cell adhesion molecules represent distinct protein families that function as specific receptors for different axon guidance cues. However, both L1 and NCAM proteins promote axonal growth by inducing neuronal tyrosine kinase activity and are coexpressed in subsets of axon tracts in arthropods and vertebrates. We have studied the functional requirements for the Drosophila L1- and NCAM-type proteins, Neuroglian (Nrg) and Fasciclin II (FasII), during postembryonic sensory axon guidance. The rescue of the Neuroglian loss-of-function (LOF) phenotype by transgenically expressed L1- and NCAM-type proteins demonstrates a functional interchangeability between these proteins in Drosophila photoreceptor pioneer axons, where both proteins are normally coexpressed. In contrast, the ectopic expression of Fasciclin II in mechanosensory neurons causes a strong enhancement of the axonal misguidance phenotype. Moreover, our findings demonstrate that this functionally redundant specificity to mediate axon guidance has been conserved in their vertebrate homologs, L1-CAM and NCAM.
Kristiansen
Lars V
LV
Instituto de Neurociencias CSIC-UMH, Universidad Miguel Hernandez, Sant Joan d'Alacant, 03550 Spain.
Velasquez
Emma
E
Romani
Susana
S
Baars
Sigrid
S
Berezin
Vladimir
V
Bock
Elisabeth
E
Hortsch
Michael
M
Garcia-Alonso
Luis
L
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics* / Q000378:metabolism; D002450:Cell Communication / Q000235:genetics; D004330:Drosophila / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins; D005123:Eye / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D020439:Growth Cones / Q000378:metabolism* / Q000648:ultrastructure; D008465:Mechanoreceptors / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D009420:Nervous System / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D039842:Neural Cell Adhesion Molecule L1 / Q000235:genetics / Q000378:metabolism; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D010641:Phenotype; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D019076:Transgenes / Q000235:genetics; D014921:Wings, Animal / Q000166:cytology / Q000196:embryology
D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules; C051642:fasciclin II; C061745:Nrg protein, Drosophila