Lee describes how X inactivation is nucleated and spreads across the X chromosome. The Xist lncRNA is known to be necessary and sufficient for X inactivation. Lee describes experiments that identified the factors that tether Xist to the X chromosome and showed how Xist spreads to cover the entire X chromosome. She then goes on to explain that Xist blocks transcription in three ways: 1) Xist recruits factors that repress transcription via epigenetic modification such as histone methylation 2) Xist repels factors that open chromatin preparing it for transcription and 3) Xist changes the 3 dimensional organization of chromosomes. Lee ends with a model of our current understanding of the complex but critical process of X chromosome inactivation.
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The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation. (Talk recorded in November 2018)
Dr. Jeannie Lee is a Professor in the Department of Genetics at Harvard Medical School and in the Department of Molecular Biology at Massachusetts General Hospital (MGH). Her lab uses X chromosome inactivation as a model to study epigenetic regulation by long noncoding RNAs. Lee received her AB in biochemistry and molecular biology from Harvard…
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