Regulation of Expression of the Calmodulin-Related TCH Genesin Plants and Cultured Cells

本实验室的长期目标是阐明植物基因表达对环境刺激的反应所涉及的分子机制和功能成分。理解这些感觉和反应通路对于理解植物发育的动态本质是至关重要的。拟南芥的TCH基因这五个基因的表达水平在雨、风、触摸、热激和黑暗等各种刺激下迅速而急剧地增加。其中三个TCH基因编码钙调蛋白相关蛋白，提示钙离子和钙调蛋白在信号转导途径中发挥作用。这项工作的重点是表征植物和培养细胞中与钙调蛋白相关的TCH基因对不同环境刺激的调节。首先，将确定转录起始点、内含子/外显子边界和多聚腺苷化位点，并确定与钙调蛋白相关的TCH2和3基因的全长cDNA序列。随后，将研究TCH-2和TCH-3在植物中积累的组织和发育特异性，重点是比较对不同刺激的反应特征。习服、脱敏和恢复的过程将以TCH mRNA的积累为指标进行研究。此外，机械胁迫、热休克和钙离子对TCH 2和TCH 3基因表达的调节将使用相对均匀和易于操作的培养根细胞来解决。由于钙离子作为第二信使在真核细胞中的普遍作用，阐明编码钙离子受体的基因的表达调控可能与将细胞外刺激转化为钙信号的多种动植物细胞有关。

The long-term objective of this laboratory is to elucidate the molecular mechanisms and the functional components involved in the regulation of plant gene expression in response to environmental stimuli. Comprehension of these sensory and response pathways is essential for understanding the dynamic nature of plant development. The expression levels of five genes, the TCH genes of Arabidopsis, are rapidly and sharply increased in response to diverse stimuli, such as rain, wind, touch, heat shock and darkness. Three of the TCH genes encode calmodulin-related proteins, suggesting roles for calcium ion and calmodulin in the signal transduction pathways. The focus of this work is to characterize the regulation of the calmoduln-related TCH genes in plants and cultured cells in response to diverse environmental stimuli. First, the transcription initiation sites, intron/exon boundaries and polyadenylation sites will be defined and the full-length cDNA sequences will be determined for the calmodulin-related TCH2 and 3 genes. Subsequently, the tissue- and developmental-specificity of TCH 2 and 3 mRNA accumulation in plants will be examined, with the emphasis on comparing the characteristics of the responses to different stimuli. The processes of habituation, desensitization and recovery will be investigated using TCH mRNA accumulation as an assay. Additionally, the regulation of TCH 2 and 3 gene expression by mechanical stress, heat shock and calcium ion will be addressed using cultured root cells that are relatively homogeneous and easily manipulated. Because of the universal role of calcium ion a second messenger in eukaryotic cells, elucidation of the regulation of expression of genes that encode calcium ion receptors will likely be relevant for the great variety of plant and animal cells that transduce extracellular stimuli into calcium signals.