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Altered levels of hsromega lncRNAs further enhance Ras signaling during ectopically activated Ras induced R7 differentiation in Drosophila
- Ray, Mukulika, Singh, Gunjan, Lakhotia, Subhash C.
- Gene expression patterns 2019 v.33 pp. 20-36
- Drosophila, RNA-binding proteins, death, eyes, messenger RNA, neoplasms, photoreceptors, pupae, sequence analysis
- We exploited the high Ras activity induced differentiation of supernumerary R7 cells in Drosophila eyes to examine if hsrω lncRNAs influence active Ras signaling. Surprisingly, either down- or up-regulation of hsrω lncRNAs in sev-GAL4>RasV12 expressing eye discs resulted in complete pupal lethality and substantially greater increase in R7 photoreceptor number at the expense of cone cells. Enhanced nuclear p-MAPK and presence of sev-GAL4 driven RasV12 bound RafRBDFLAG in cells not expressing the sev-GAL4 driver indicated non-cell autonomous spread of Ras signaling when hsrω levels were co-altered. RNA-sequencing revealed that down-and up-regulation of hsrω transcripts in sev-GAL4>RasV12 expressing eye discs elevated transcripts of positive or negative modulators, respectively, of Ras signaling so that either condition enhances it. Altered hsrω transcript levels in sev-GAL4>RasV12 expressing discs also affected sn/sno/sca RNAs and some other RNA processing transcript levels. Post-transcriptional changes due to the disrupted intra-cellular dynamicity of omega speckle associated hnRNPs and other RNA-binding proteins that follow down- or up-regulation of hsrω lncRNAs appear to be responsible for the further elevated Ras signaling. Cell autonomous and non-autonomous enhancement of Ras signaling by lncRNAs like hsrω has implications for cell signaling during high Ras activity commonly associated with some cancers.