Active Erasure of Short-term Cellular Memory by Histone H3K4 Methylation

Cells confer short-term memory for better adaptation to a new environment. However, for the “adaptive” changes to a certain stimulus, some are beneficial but some may be not. Irreversible cellular changes may result in either evolution or diseases. Therefore, cells must possess an ability to erase the recent “adaptive” changes in order to reset their inherited status. A generally accepted argument is that cells passively lose memory in a time-dependent manner due to cell division. Study from Dr. ZHOU Jinqiu’s lab challenged this view by reporting, for the first time, an active, cell division-independent mechanism for memory loss, which is encoded by the chromatin.

 

Using galactose memory as a model, they found that transcriptional inactivation of GAL1 induced histone H3K4 methylation across the GAL1 gene, which significantly suppressed the reactivation of GAL1 and thereby accelerated the loss of galactose memory. Notably, the H3K4 methylation recruited the Isw1 ATPase to the recently repressed GAL1 so as to limit the processivity of RNA Pol II during GAL1 reactivation. They further showed that the transcriptional inactivation-induced H3K4 methylation suppresses transcriptional reactivation for many other nutrient-responsive genes. ZHOU’s work reveals a transcriptional inactivation-driven chromatin remodeling process that specifically acts on transcriptional reactivation. It suggests that H3K4 methylation help yeast cells quickly restore inherited epigenetic state after recent experience.

 

This work entitled “Recent Transcription-induced Histone H3 Lysine 4 (H3K4) Methylation Inhibits Gene Reactivation” was published on Journal of Biological Chemistry at Oct 7^th, 2011.

 

This study was supported by the grants from the National Natural Science Foundation of China and Ministry of Science and Technology.(SIBCB)

 

AUTHOR CONTACT:

ZHOU Jinqiu

Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China

Phone: 86-21-54921076; Email: jqzhou@sibs.ac.cn