The long and the short of it: RNA-directed chromatin asymmetry in mammalian X-chromosome inactivation.
Mammalian X-chromosome inactivation is controlled by a multilayered silencing pathway involving both short and long non-coding RNAs, which differentially recruit the epigenetic machinery to establish chromatin asymmetries. In response to developmentally regulated small RNAs, dicer, a key effector of RNA interference, locally silences Xist on the active X-chromosome and establishes the heterochromatin conformation along the silent X-chromosome. The 1.6 kb RepA RNA initiates silencing by targeting the PRC2 polycomb complex to the inactive X-chromosome. In addition, the nuclear microenvironment is implicated in the initiation and maintenance of X-chromosome asymmetries. Here we review new findings involving these various RNA species in terms of understanding Xist gene regulation and the establishment of X-chromosome inactivation.
Kanduri
Chandrasekhar
C
Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden. kanduri.chandrasekhar@genpat.uu.se
Whitehead
Joanne
J
Mohammad
Faizaan
F
D000818:Animals; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D012313:RNA / Q000235:genetics* / Q000378:metabolism*; D049951:X Chromosome Inactivation / Q000235:genetics*
D002843:Chromatin; D012313:RNA