RT Journal Article SR Electronic T1 Targeting of the dosage-compensated male X-chromosome during early Drosophila development JF bioRxiv FD Cold Spring Harbor Laboratory SP 671073 DO 10.1101/671073 A1 LE Rieder A1 WT Jordan III A1 EN Larschan YR 2019 UL http://biorxiv.org/content/early/2019/06/14/671073.abstract AB The essential process of dosage compensation, which corrects for the imbalance in X-linked gene expression between XX females and XY males, represents a key model for how genes are targeted for coordinated regulation. However, the mechanism by which dosage compensation complexes identify the X-chromosome during early development remained unknown because of the difficulty of sexing embryos prior to zygotic transcription. We used meiotic drive to sex Drosophila embryos prior to zygotic transcription and ChIP-seq to measure dynamics of dosage compensation factor targeting. The Drosophila Male-Specific Lethal dosage compensation complex (MSLc) requires the ubiquitous zinc-finger protein Chromatin-Linked Adaptor for MSL Proteins (CLAMP) to identify the X-chromosome. We observe a multi-stage process in which MSLc first identifies CLAMP binding sites throughout the genome followed by concentration at the strongest X-linked MSLc sites. We provide insight into the dynamic mechanism by which a large transcription complex identifies its binding sites during early development.