X chromosome dosage compensation in Drosophila and Lucilia

In Drosophila, the male-specific lethal (MSL) complex is essential for X chromosomeChrom pic MSL dosage compensation. The core MSL complex comprises 5 proteins and two long non-coding RNAs called roX RNAs. Previously, we have worked on the central roles of MSL1 and MSL2 in binding of the MSL complex to male X chromosome. For example, we found that the C terminal domain of MSL2 is essential for incorporation of the roX RNAs into the MSL complex and X chromosome binding. We are currently collaborating with Dr. Stan Moore on a structure-function analysis of the domains of the MOF protein, which is one of the MSL proteins. MOF is responsible for acetylating histone H4 at lysine 16, an epigenetic mark enriched on the male X chromosome.

Genes that are X-linked in Drosophila are autosomal in Lucilia. We found that many genes that are on the tiny fourth chromosome in Drosophila are X-linked and dosage compensated in Lucilia.  We showed that a gene we called “no blokes” is essential for normal X chromosome gene expression and male viability. no blokes is an ortholog of Drosophila painting of fourth.