MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China.
New Phytol. 2012 Jul;195(1):85-96. doi: 10.1111/j.1469-8137.2012.04131.x. Epub 2012 Apr 12.
• Vacuolar processing enzyme (VPE), a cysteine protease, has been intensively studied in plant hypersensitive cell death, but the role and molecular mechanism of VPEs in response to abiotic stresses remain unclear. This work investigated the involvement of VPEs in Arabidopsis response to heat stress. • Under heat shock (HS), Arabidopsis VPE activity and the transcript level of γVPE were both upregulated, and γVPE deficiency suppressed vacuolar disruption and delayed caspase-3-like activation in HS-induced programmed cell death (PCD). Moreover, the change of VPE activity generally paralleled the alteration of caspase-1-like activity under HS treatment, indicating that HS-induced VPE activity might exhibit the caspase-1-like activity. • Further studies showed that MAP Kinase 6 (MPK6) activity was increased after HS treatment, and experiments with inhibitors and mutants suggested that MPK6 was responsible for the γVPE activation after HS treatment. In response to HS stress, reactive oxygen species (ROS) production, increase of cytoplasmic calcium concentration (Ca(2+) ) and the upregulation of calmodulin 3 (CaM3) transcript level occurred upstream of MPK6 activation. • Our results suggested that activation of Arabidopsis γVPE was mediated by MPK6 and played an important role in HS-induced Arabidopsis PCD, providing new insight into the mechanistic study of plant VPEs.
• 液泡加工酶（VPE）是一种半胱氨酸蛋白酶，在植物超敏细胞死亡中得到了深入研究，但 VPEs 对应激的作用和分子机制仍不清楚。本研究探讨了 VPEs 在拟南芥对热应激反应中的参与情况。• 在热激（HS）下，拟南芥 VPE 活性和 γVPE 的转录水平均上调，而 γVPE 缺失抑制了热诱导程序性细胞死亡（PCD）中液泡的破坏和半胱天冬酶-3 样的延迟激活。此外，VPE 活性的变化通常与 HS 处理下半胱天冬酶-1 样活性的变化平行，表明 HS 诱导的 VPE 活性可能表现出半胱天冬酶-1 样活性。• 进一步的研究表明，MAP 激酶 6（MPK6）活性在 HS 处理后增加，抑制剂和突变体实验表明，MPK6 负责 HS 处理后 γVPE 的激活。在响应 HS 胁迫时，ROS 产生、细胞质钙离子浓度 (Ca(2+) )增加和钙调素 3（CaM3）转录水平上调发生在 MPK6 激活的上游。• 我们的结果表明，拟南芥 γVPE 的激活是由 MPK6 介导的，并在 HS 诱导的拟南芥 PCD 中发挥重要作用，为植物 VPEs 的机制研究提供了新的见解。
