A heat‐activated calcium‐permeable channel – Arabidopsis cyclic nucleotide‐gated ion channel 6 – is involved in heat shock responses

• Published in: The Plant journal : for cell and molecular biology 2012-06, Vol.70 (6), p.1056-1069
• Main Authors: Gao, Fei, Han, Xiaowei, Wu, Jianhai, Zheng, Shuzhi, Shang, Zhonglin, Sun, Daye, Zhou, Rengang, Li, Bing
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - physiology; Biological and medical sciences; Ca2+‐permeable channel; Calcium - metabolism; cAMP; Cell membranes. Ionic channels. Membrane pores; Cell structures and functions; CNGC6; Cyclic AMP - metabolism; Cyclic Nucleotide-Gated Cation Channels - genetics; Cyclic Nucleotide-Gated Cation Channels - physiology; Cytosol - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Heat-Shock Proteins - physiology; Heat-Shock Response; Molecular and cellular biology; Mutagenesis, Insertional; Patch-Clamp Techniques; Plant physiology and development; Signal Transduction; thermotolerance
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2012.04969.x

Summary An increased concentration of cytosolic calcium ions (Ca2+) is an early response by plant cells to heat shock. However, the molecular mechanism underlying the heat‐induced initial Ca2+ response in plants is unclear. In this study, we identified and characterized a heat‐activated Ca2+‐permeable channel in the plasma membrane of Arabidopsis thaliana root protoplasts using reverse genetic analysis and the whole‐cell patch‐clamp technique. The results indicated that A. thaliana cyclic nucleotide‐gated ion channel 6 (CNGC6) mediates heat‐induced Ca2+ influx and facilitates expression of heat shock protein (HSP) genes and the acquisition of thermotolerance. GUS and GFP reporter assays showed that CNGC6 expression is ubiquitous in A. thaliana, and the protein is localized to the plasma membrane of cells. Furthermore, it was found that the level of cytosolic cAMP was increased by a mild heat shock, that CNGC6 was activated by cytosolic cAMP, and that exogenous cAMP promoted the expression of HSP genes. The results reveal the role of cAMP in transduction of heat shock signals in plants. The correlation of an increased level of cytosolic cAMP in a heat‐shocked plant with activation of the Ca2+ channels and downstream expression of HSP genes sheds some light on how plants transduce a heat stimulus into a signal cascade that leads to a heat shock response.