2016年3月22日 訊 /生物谷BIOON/--長春花(Catharanthus roseus)能夠產生可用於治療癌症、心律失常和其他疾病的有機化合物。在最新發表於《Proceedings of the National Academy of Sciences,PNAS 》的研究中,一個日本研究團隊揭示了這些化合物在細胞水平的代謝過程細節。他們的數據表明,存在一種未知機制,調節這些化合物在植物中的創造、移動和分布。
植物基本是靜止不動的,為了保護自身免受昆蟲、野生動物和疾病的侵害,它們創建出一個化學化合物自衛系統,所涉及的化合物被稱為次生代謝物。這些化合物大部分存儲於植物細胞的液泡之中,並在動物吞吃植物時被激活。人類使用這些代謝物作為藥物和興奮劑(它們包含尼古丁和咖啡因)已經有很長的歷史。
長春花能夠產生被歸類為萜類吲哚生物鹼(terpenoid indole alkaloids,TIAs)的抗腫瘤化合物。在代謝TIAs的過程中,各種中間化合物被創造並穿越不同的細胞,最後到達存儲它們的異形細胞或乳汁管細胞。但直到現在依然不清楚每種化合物如何在細胞之間移動,如何控制它們在每種細胞中的創造和存儲。
該研究團隊使用質譜成像技術和單細胞質譜技術分析了每種化合物在組織和單個細胞中的發布。分析顯示,之前認為在表皮細胞中代謝和存儲的化合物,實際上大量存在於完全不同的位置--異形細胞。
這些發現表明,可能存在一種調節這些有機化合物在植物中創造、移動和管理的未知機制。此外,闡明有價值的化合物在植物中代謝過程的細節,可能有助於開發新的合成有機化合物的方法。(生物谷Bioon.com)
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DOI:10.1073/pnas.1521959113
Cell-specific localization of alkaloids in Catharanthus roseusstem tissue measured with Imaging MS and Single-cell MS
Catharanthus roseus (L.) G. Don is a medicinal plant well known for producing antitumor drugs such as vinblastine and vincristine, which are classified as terpenoid indole alkaloids (TIAs). The TIA metabolic pathway in C. roseus has been extensively studied. However, the localization of TIA intermediates at the cellular level has not been demonstrated directly. In the present study, the metabolic pathway of TIA in C. roseus was studied with two forefront metabolomic techniques, that is, Imaging mass spectrometry (MS) and live Single-cell MS, to elucidate cell-specific TIA localization in the stem tissue. Imaging MS indicated that most TIAs localize in the idioblast and laticifer cells, which emit blue fluorescence under UV excitation. Single-cell MS was applied to four different kinds of cells [idioblast (specialized parenchyma cell), laticifer, parenchyma, and epidermal cells] in the stem longitudinal section. Principal component analysis of Imaging MS and Single-cell MS spectra of these cells showed that similar alkaloids accumulate in both idioblast cell and laticifer cell. From MS/MS analysis of Single-cell MS spectra, catharanthine, ajmalicine, and strictosidine were found in both cell types in C. roseus stem tissue, where serpentine was also accumulated. Based on these data, we discuss the significance of TIA synthesis and accumulation in the idioblast and laticifer cells of C. roseus stem tissue.