Transmembrane/juxtamembrane domain-dependent Dscam distribution and function during mushroom body neuronal morphogenesis.
Besides 19,008 possible ectodomains, Drosophila Dscam contains two alternative transmembrane/juxtamembrane segments, respectively, derived from exon 17.1 and exon 17.2. We wondered whether specific Dscam isoforms mediate formation and segregation of axonal branches in the Drosophila mushroom bodies (MBs). Removal of various subsets of the 12 exon 4s does not affect MB neuronal morphogenesis, while expression of a Dscam transgene only partially rescues Dscam mutant phenotypes. Interestingly, differential rescuing effects are observed between two Dscam transgenes that each possesses one of the two possible exon 17s. Axon bifurcation/segregation abnormalities are better rescued by the exon 17.2-containing transgene, but coexpression of both transgenes is required for rescuing mutant viability. Meanwhile, exon 17.1 targets ectopically expressed Dscam-GFP to dendrites while Dscam[exon 17.2]-GFP is enriched in axons; only Dscam[exon 17.2] affects MB axons. These results suggest that exon 17.1 is minimally involved in axonal morphogenesis and that morphogenesis of MB axons probably involves multiple distinct exon 17.2-containing Dscam isoforms.
Wang
Jian
J
Department of Cell and Structural Biology, University of Illinois, Urbana 61801, USA.
Ma
Xiaojun
X
Yang
Jacob S
JS
Zheng
Xiaoyan
X
Zugates
Christopher T
CT
Lee
Ching-Hsien J
CH
Lee
Tzumin
T
D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D015815:Cell Adhesion Molecules; D002454:Cell Differentiation / Q000235:genetics; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D005091:Exons / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D020439:Growth Cones / Q000378:metabolism / Q000648:ultrastructure; D007814:Larva; D009024:Morphogenesis / Q000235:genetics; D024521:Mushroom Bodies / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes / Q000235:genetics
D015815:Cell Adhesion Molecules; D029721:Drosophila Proteins; C491736:Dscam1 protein, Drosophila; D020033:Protein Isoforms; D011506:Proteins