Okimura Yuya, Fujita Hirofumi, Ogino Tetsuya, Inoue Keiji, Shuin Toro, Yano Hiromi, Yasuda Tatsuji, Inoue Masayasu, Utsumi Kozo, Sasaki Junzo
Department of Cytology & Histology, Okayama University Graduate School, Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama, Okayama 700-8558, Japan.
Physiol Chem Phys Med NMR. 2007;39(1):69-82.
The aim of the present work is to clarify the mechanism(s) that regulates the accumulation of protoporphyrin IX (PpIX) in human histiocytic lymphoma cell line U937 incubated with 5-aminolevulinic acid (ALA). Biosynthesis and accumulation of PpIX in the cells was determined after incubation with 0.1-5 mM ALA using a flow cytometric technique. The synthesized endogenous PpIX was found to localize predominantly in the mitochondrial region of the cells. The ALA-enhanced PpIX synthesis was suppressed by the presence of either beta-alanine, a competitive inhibitor of beta-transporters on cell membranes, or carbonyl cyanide p-trifluoromethoxyphenyl hydrazone, an uncoupler of mitochondrial oxidative phosphorylation. In contrast, cellular accumulation of PpIX was enhanced by the presence of either deferoxamine (an iron chelater), MnCl2 (a ferrochelatase inhibitor), or Sn-mesoporphyrin (heme oxygenase inhibitor). These results suggest that ALA-enhanced accumulation of PpIX in U937 cells was regulated by cellular uptake and conversion of ALA to PpIX and by degradation of Heme.
本研究的目的是阐明在与5-氨基乙酰丙酸（ALA）孵育的人组织细胞淋巴瘤细胞系U937中调节原卟啉IX（PpIX）积累的机制。使用流式细胞术技术，在与0.1-5 mM ALA孵育后，测定细胞中PpIX的生物合成和积累。发现合成的内源性PpIX主要定位于细胞的线粒体区域。细胞膜上β转运蛋白的竞争性抑制剂β-丙氨酸或线粒体氧化磷酸化解偶联剂羰基氰对三氟甲氧基苯腙的存在抑制了ALA增强的PpIX合成。相反，去铁胺（一种铁螯合剂）、MnCl2（一种亚铁螯合酶抑制剂）或锡-中卟啉（血红素加氧酶抑制剂）的存在增强了细胞对PpIX的积累。这些结果表明，ALA增强的U937细胞中PpIX的积累受ALA的细胞摄取、ALA向PpIX的转化以及血红素降解的调节。
