AbstractHyperactivity of the single X-chromosome in male Drosophila is achieved by establishing a ribonucleoprotein complex, called Dosage Compensation Complex (DCC), on the male X chromosome. Msl-1 and Msl-2 proteins, involved in the initiation and establishing of DCC on male X chromosome, are very crucial component of this complex. In the present study, it has been found here that a long non-coding RNA gene hsrω genetically interacts with Msl-1 as well as Msl-2 and suppresses the lethal phenotype of Msl-1 or Msl-2 down-regulation in its up-regulated background. Additionally, it is also found here that an ATP-dependent chromatin remodeler, NURF301, also interacts with hsrω in same manner. General lethality caused by Act-GAL4 driven global expression of NURF301-RNAi and the male-specific lethality following Msl-1-RNAi or Msl-2-RNAi transgene expression were partially suppressed by over-expression of hsrω, but not by down regulation through hsrω-RNAi. Likewise, eye phenotypes following ey-GAL4 driven down-regulation of NURF301 or Msl-1 or Msl-2 were also partially suppressed by over-expression of hsrω. Act-GAL4 driven global over-expression of hsrω along with Msl-1-RNAi or Msl-2-RNAi transgene substantially restored levels of MSL-2 protein on the male X chromosome. Similarly, levels and distribution of Megator protein, which was reduced and distribution at nuclear rim and in nucleoplasm was affected in the MT and SG nuclei, is also restored when hsrω transcripts are down-regulated in Act-GAL4 driven Msl-1-RNAi or Msl-2-RNAi genetic background. NURF301, a known chromatin remodeler, when down-regulated shows decondensed X chromosome in male larvae. Down-regulation of hsrω results in restoration of chromosome architecture without affecting the level of ISWI protein-another chromatin remodeler protein, known to interacting with hsrω.
Differential Occupancy of Two GA-Binding Proteins Promotes Targeting of the Drosophila Dosage Compensation Complex to the Male X Chromosome
