A search for Drosophila neural precursor genes identifies ran.
The Drosophila ran gene has been isolated in a differential cDNA screen designed to identify genes that are dynamically expressed in embryonic neuroblasts. The guanine triphosphate (GTP)-binding Ran protein, a member of the Ras superfamily, has been shown to participate in a variety of transport related processes in other organisms. Drosophila ran codes for a 216 amino acid (aa) protein that shares 78% and 86% identity with the yeast and human Ran proteins, respectively. Database searches have identified a second Drosophila ran gene, ran-like. The predicted Ran-like protein shares 59% identity with its isoform. Embryo in situ mRNA localization of ran and ran-like expression reveals that both are maternally expressed; however zygotic ran expression is restricted to central nervous system (CNS) neuroblasts undergoing late lineage formation, while ran-like expression is detected in the developing trachea and salivary gland. To investigate the significance of ran-restricted CNS expression, we have targeted its misexpression to different temporal windows of CNS development. In addition, a dominant-negative mutant form of ran was targeted to the developing CNS and to the larval eye/antenna imaginal disc to assess the role of ran-dependent functions. Embryonic CNS misexpression of the mutant, but not wild-type, ran results in larval death. Neither wild-type nor mutant ran misexpression had any detectable effect on embryonic CNS lineage specification, nuclear transport of a number of CNS-specific transcription factors or axonal guidance. However, expression of the dominant-negative mutant ran in the developing eye/antenna disc did result in a severe adult eye phenotype marked by apoptosis of photoreceptor, cone and pigment cells.
Koizumi
K
K
The Neurogenetics Unit, Laboratory of Neurochemistry, NINDS, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Stivers
C
C
Brody
T
T
Zangeneh
S
S
Mozer
B
B
Odenwald
W F
WF
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D003001:Cloning, Molecular; D004330:Drosophila / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D005799:Genes, Dominant / Q000235:genetics; D017344:Genes, Insect / Q000235:genetics*; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009420:Nervous System / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D029721:Drosophila Proteins; D012333:RNA, Messenger; D020931:ran GTP-Binding Protein