[The roles of cytochrome P450 metabolites of arachidonic acid in the regulation of vascular function].

Arachidonic acids (AA) widely exist in multiple organs and can be metabolized into small lipid molecules with strong biological functions through several pathways. Among them, epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE), which are produced by cytochrome P450 enzymes, have attracted a lot of attentions, especially in vascular homeostasis. The regulation of vascular function is the foundation of vascular homeostasis, which is mainly achieved by manipulating the vascular structure and biological function. In the past 30 years, the roles of EETs and 20-HETE in the regulation of vascular function have been widely explored. In this review, we discussed the effects of EETs and 20-HETE on angiogenesis and vascular inflammation, respectively. Generally, EETs can dilate blood vessels and inhibit vascular inflammation, while 20-HETE can induce vasoconstriction and vascular inflammation. Interestingly, both EETs and 20-HETE can promote angiogenesis. In addition, the roles of EETs and 20-HETE in several vascular diseases, such as hypertension and cardiac ischemia, were discussed. Finally, the therapeutic perspectives of EETs and 20-HETE for vascular diseases were also summarized.

Map-based cloning of zb7 encoding an IPP and DMAPP synthase in the MEP pathway of maize.

IspH is a key enzyme in the last step of the methyl-D-erythritol-4-phosphate (MEP) pathway. Loss of function of IspH can often result in complete yellow or albino phenotype in many plants. Here, we report the characterization of a recessive mutant of maize, zebra7 (zb7), showing transverse green/yellow striped leaves in young plants. The yellow bands of the mutant have decreased levels of chlorophylls and carotenoids with delayed chloroplast development. Low temperature suppressed mutant phenotype, while alternate light/dark cycle or high temperature enlarged the yellow section. Map-based cloning demonstrated that zb7 encodes the IspH protein with a mis-sense mutation in a conserved region. Transgenic silencing of Zb7 in maize resulted in complete albino plantlets that are aborted in a few weeks, confirming that Zb7 is important in the early stages of maize chloroplast development. Zb7 is constitutively expressed and its expression subject to a 16-h light/8-h dark cycle regulation. Our results suggest that the less effective or unstable IspH in zb7 mutant, together with its diurnal expression, are mechanistically accounted for the zebra phenotype. The increased IspH mRNA in the leaves of zb7 at the late development stage may explain the restoration of mutant phenotype in mature stages.