Page 10 - ebook

[A. Biochemistry/Molecular Biology] A-5

Phenotypic and functional analyses for individual subunits of

Rpd3L HDAC upon environmental stresses

Hajung Shin¹, TaeSoo Kim¹*

¹Life science, Ewha womans university, Seoul 03760, Korea

Rpd3L HDAC mainly deacetylates histones at promoter regions to repress transcription by RNA Polymerase II (RNA
Pol II). A previous study showed that mutants for several subunits of Rpd3L HDAC were sensitive to heat shock

stress probably because of defects in the induction of genes required for cell survival upon heat shock. To explore
the functions of all individual subunits of Rpd3L HDAC in heat shock response, we monitored the heat-sensitive

phenotypes of all mutants for Rpd3L. Interestingly, Rpd3L components were divided into four groups based on their
heat sensitivity. In addition, global gene expression changes were analyzed upon heat shock stress using mutants

from each group. All mutants tested showed defects in gene induction even though they exhibited differential
sensitivities to heat shock. In contrast, gene repression upon heat shock is more closely related to the heat-sensitivity

of each mutant. Finally, the sensitivity of individual mutants for Rpd3L subunits varied with stresses (osmotic pressure
or DNA replication stress). These findings suggest that proper gene repression by Rpd3L HDAC may support cell

fitness upon heat shock. Furthermore, Rpd3L HDAC may have sub-complexes supporting cell viability under different
stress conditions.