Systemic Comparison of Heat Shock Response Induced by Heat Shock and a Proteasome Inhibitor in Mouse Fibrosarcoma Cells and Their Thermotolerant Counterparts

Heat shock response (HSR) is a cellular defense mechanism against various stresses. Both heat shock and proteasome inhibitor MG132 cause the induction of heat shock proteins, a distinct feature of HSR. To better understand the molecular basis of HSR, we subjected the mouse fibrosarcoma cell line, RIF-1, and its thermotolerant variant, TR-RIF-1 cells, to heat shock and MG132. We compared mRNA expressions using microarray analysis during recovery after heat shock and MG132 treatment. This study led us to group the 3,245 up-regulated genes by heat shock and MG132 into three families: genes regulated 1) by both heat shock and MG132 (e.g. chaperones); 2) by heat shock (e.g. DNA-binding proteins including histones); and 3) by MG132 (e.g. innate immunity and defense-related molecules). RIF-1 and TR cells were heat shock treated or MG132 treated and harvested after various times of recovery. mRNA expressions were compared to untreated samples. Biological replication was done.