The zinc finger protein Zn72D and DEAD box helicase Belle interact and control maleless mRNA and protein levels.
BACKGROUND
The Male Specific Lethal (MSL) complex is enriched on the single X chromosome in male Drosophila cells and functions to upregulate X-linked gene expression and equalize X-linked gene dosage with XX females. The zinc finger protein Zn72D is required for productive splicing of the maleless (mle) transcript, which encodes an essential subunit of the MSL complex. In the absence of Zn72D, MLE levels are decreased, and as a result, the MSL complex no longer localizes to the X chromosome and dosage compensation is disrupted. To understand the molecular basis of Zn72D function, we identified proteins that interact with Zn72D.


RESULTS
Among several proteins that associate with Zn72D, we found the DEAD box helicase Belle (Bel). Simultaneous knockdown of Zn72D and bel restored MSL complex localization to the X chromosome and dosage compensation. MLE protein was restored to 70% of wild-type levels, although the level of productively spliced mle transcript was still four-fold lower than in wild-type cells. The increase in production of MLE protein relative to the amount of correctly spliced mle mRNA could not be attributed to an alteration in MLE stability.


CONCLUSIONS
These data indicate that Zn72D and Bel work together to control mle splicing and protein levels. Thus Zn72D and Bel may be factors that coordinate splicing and translational regulation.
Worringer
Kathleen A
KA
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA. kworringer@gladstone.ucsf.edu
Chu
Feixia
F
Panning
Barbara
B
D000818:Animals; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012326:RNA Splicing / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D014960:X Chromosome / Q000235:genetics
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D003513:Cycloheximide; D053487:DEAD-box RNA Helicases