LOLA ENCODES A PUTATIVE TRANSCRIPTION FACTOR REQUIRED FOR AXON GROWTHAND GUIDANCE IN DROSOPHILA

Mutations in the gene longitudinals lacking (lola) lead to defects in the development of axon tracts in the Drosophila embryonic central ner vous system. We now show that lola mutations also cause defects of axo n growth and guidance in the peripheral nervous system, and causes a p articular cluster of embryonic sense organs (lch5) to be oriented impr operly. Axonal aberrations caused by lola are similar to those caused by mutations of three other genes, logo, Notch and Delta, raising the possibility that lola works in the same genetic pathway as do these ot her molecules. The lola gene encodes at least two nuclear protein prod ucts, apparently by differential RNA splicing. The predicted proteins contain an amino-terminal motif similar to that recently described for a family of transcription factors, including the products of the Dros ophila genes tramtrack and the Broad Complex. Like Ttk and BR-C, one o f the two characterized products of the lola locus bears sequences sim ilar to the zinc-finger motif, but the other (neuronal) form of the pr otein has no recognizable DNA-binding motif.