Gene Regulation in Glyoxysome Biogenesis

乙氧基体是一种特殊的过氧化物体，含有动员脂质至关重要的酶。为了研究参与细胞器生物发生的过程，原田博士正在研究编码异柠檬酸裂解酶和苹果酸合成酶的基因的调控，这两种乙醛酸循环酶只与乙氧基体相关。这些基因在发育过程中受到调控；它们在幼苗、发育中的种子、衰老的器官和花粉中表达，但在成熟植物的非衰老器官中不表达。此外，基因的调节主要发生在转录水平。该提案的长期目标是定义调节这些基因的生理信号，从而控制糖氧体的生物发生。随之而来的一个目标是确定在植物生命周期的不同时期是否有共同的信号调节这些基因。提出了两种主要方法来解决这些问题。首先，原田博士将定位顺式作用元件，并确定与这些元件相互作用的DNA结合蛋白，以获得对基因调控的机械性理解。其次，他将识别基因表达改变的突变，以开始定义调控基因的途径的组成部分。他预计，这些互补性研究最终将为控制糖氧体生物发生的生理线索提供洞察力。

Glyoxysomes are specialized peroxisomes that contain enzymes critically required for the mobilization of lipids. To study processes involved in the biogenesis of the organelle, Dr. Harada is investigating the regulation of genes encoding isocitrate lyase and malate synthase, two glyoxylate cycle enzymes that are associated exclusively with glyoxysomes. The genes are regulated developmentally; they are expressed in seedlings, developing seeds, senescent organs, and in pollen but not in non-senescent organs of the mature plant. Moreover, regulation of the genes occurs primarily at the transcriptional level. The proposal's long term goal is to define the physiological signals that regulate these genes, and, therefore, control glyoxysome biogenesis. An accompanying objective is to determine whether a common signal regulates these genes at different periods of the plant life cycle. Two primary approaches are proposed to address these issues. First, Dr. Harada will localize cis-acting elements and identify the DNA binding proteins that interact with these elements to obtain a mechanistic understanding of the regulation of the genes. Second, he will identify mutants altered in the expression of the genes to begin to define components of the pathway regulating the genes. He anticipates that these complementary studies ultimately will provide insight into the physiological cues that control glyoxysome biogenesis.