Induction of the heat shock response in Arabidopsis by heat shock protein 70 inhibitor VER-155008

Abstract

The heat shock protein 90 (HSP90) inhibitor, geldanamycin, is a chemical inducer of the heat shock response (HSR) in Arabidopsis. Geldanamycin is thought to activate the heat shock signal by dissociating the HSP90-heat shock factor (HSF) complex. Recent studies have indicated that plant HSP70 is also associated with HSF, suggesting that inhibition of HSP70 may induce the HSR. However, no studies have been conducted to test this hypothesis. Here, we found that a specific HSP70 inhibitor VER-155008 activated the promoter of a small HSP gene (At1 g53540, HSP17.6C-CI) of Arabidopsis, which was shown to be activated by geldanamycin and other HSP90 inhibitors. The production of HSP17.6C-CI, HSP70 and HSP90.1 proteins in Arabidopsis was enhanced by the addition of VER-155008. The reduction of chlorophyll contents by heat shock was ameliorated by VER-155008. Chaperone analyses indicated that VER-155008 inhibited the chaperone activities of wheat germ extract and human HSP70/HSP40, respectively. These results suggest that the inhibition of HSP70 by VER-155008 enhanced the heat tolerance of Arabidopsis by inducing the HSR in the plant.

HSP70‐16 and VDAC3 jointly inhibit seed germination under cold stress in Arabidopsis

“…These results indicated that HSP70‐16 and VDAC3 may function closely in negatively regulating seed germination under cold stress. Since HSP70‐16 is a chaperone/ATPase (Figure S2), we further examined if the inhibitory effect of HSP70‐16 on seed germination under cold stress is from its chaperone activity using a plant HSP70 ATPase activity inhibitor VER155008 (Zhang et al ., 2015; Matsuoka et al ., 2019). Neither mutant seeds ( hsp70‐16 , vdac3 and hsp70‐16vdac3 ) nor wild‐type seeds changed their earlier germination patterns under 4°C up to 196 h in the presence of VER155008 (25 μM or 50 μM) (Figure 1c), indicating that HSP70‐16 negatively regulates seed germination under cold stress in a manner that is independent of its chaperone activity.…”

Potential use of essential oils to enhance heat tolerance in plants

“…GDA and sanguinarine inhibited luciferase folding by wheat (Triticum aestivum L.) germ chaperones at similar efficiencies [47]. This suggests that sanguinarine induces HSR probably via the inhibition of chaperones that hold HSF [48]. However, it is unclear how essential oil HTLEs such as isothiocyanates and monoterpenes promote HSR in plants.…”