In the fly Drosophila melanogaster, the Dosage Compensation Complex (DCC) allows the single X chromosome of males to produce as much protein as the two X chromosomes of females. How heterochromatin - a tightly packed form of DNA and proteins - impacts dosage compensation in Flies? That is the question addressed by Marion Delattre, Anne Spierer, and Flora Begeot - members of Pr Pierre Spierer's laboratory - in a paper just published in the PLoS genetics journal. They have shown that SU(VAR)3-7 - a heterochromatic protein - is involved in the restricted localization of the DCC to the male X chromosome. The absence of maternally provided SU(VAR)3-7 renders dosage compensation toxic in males and this protein is also involved in the dosage compensated expression of the X-linked white gene. Taken together, the results shown in this paper bring to light a link between heterochromatin and dosage compensation.
Picture: H4K16ac immunodetection on chromosomes of wild type males or males harbouring two copies of the heat-shock transgene over-expressing Su(var)3-7 (Su(var)3-7+++/Su(var)3-7+++).