Dosage compensation mechanisms provide a paradigm to study the contribution of 
chromosomal conformation toward targeting and spreading of epigenetic regulators 
over a specific chromosome. By using Hi-C and 4C analyses, we show that 
high-affinity sites (HAS), landing platforms of the male-specific lethal (MSL) 
complex, are enriched around topologically associating domain (TAD) boundaries 
on the X chromosome and harbor more long-range contacts in a sex-independent 
manner. Ectopically expressed roX1 and roX2 RNAs target HAS on the X chromosome 
in trans and, via spatial proximity, induce spreading of the MSL complex in cis, 
leading to increased expression of neighboring autosomal genes. We show that the 
MSL complex regulates nucleosome positioning at HAS, therefore acting locally 
rather than influencing the overall chromosomal architecture. We propose that 
the sex-independent, three-dimensional conformation of the X chromosome poises 
it for exploitation by the MSL complex, thereby facilitating spreading in males.