He D, Behar S, Nomura N, Sassa S, Lim H W
Dermatology Service, Department of Veterans Affairs Medical Center, New York, NY 10010, USA.
Photochem Photobiol. 1995 Jun;61(6):656-61. doi: 10.1111/j.1751-1097.1995.tb09884.x.
To study porphyrin biosynthesis in human microvascular endothelial cells, HMEC-1 cells, a transformed human microvascular endothelial cell line, were incubated with 5-aminolevulinic acid (ALA), the precursor of endogenous porphyrins, and porphyrin accumulation was measured spectro-fluorometrically. The HMEC-1 cells accumulated porphyrin in a concentration-related and a time-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated in the cells. The effect of light on protoporphyrin accumulation was evaluated by exposing the ALA-loaded HMEC-1 cells to ultraviolet-A (UVA) and blue light, followed by another incubation with ALA for 2-24 h. Enhancement of protoporphyrin accumulation in irradiated HMEC-1 cells was observed 2-24 h after irradiation, which was associated with a decrease in ferrochelatase protein and activity. Porphyrin accumulation from ALA after irradiation was significantly decreased when catalase (750-3000 U/mL, 29.3-44.3% suppression) or superoxide dismutase (270 U/mL, 36.4% suppression) was present during irradiation. These data demonstrate that HMEC-1 cells were capable of porphyrin biosynthesis, and that exposure of protoporphyrin-containing HMEC-1 cells to UVA and blue light, which includes the Soret band spectrum, decreased the ferrochelatase activity and its protein. These changes were mediated, at least in part, by reactive oxygen species.
为研究人微血管内皮细胞中的卟啉生物合成，将人微血管内皮细胞系HMEC-1细胞与内源性卟啉的前体5-氨基乙酰丙酸（ALA）一起孵育，并用荧光分光光度法测量卟啉积累量。HMEC-1细胞以浓度和时间依赖的方式积累卟啉。原卟啉是细胞中积累的主要卟啉。通过将加载ALA的HMEC-1细胞暴露于紫外线-A（UVA）和蓝光下，然后再与ALA孵育2至24小时，评估光对原卟啉积累的影响。在照射后2至24小时观察到照射的HMEC-1细胞中原卟啉积累增加，这与亚铁螯合酶蛋白和活性的降低有关。当在照射期间存在过氧化氢酶（750 - 3000 U/mL，抑制率29.3 - 44.3%）或超氧化物歧化酶（270 U/mL，抑制率36.4%）时，照射后从ALA积累的卟啉显著减少。这些数据表明，HMEC-1细胞能够进行卟啉生物合成，并且将含原卟啉的HMEC-1细胞暴露于包括索雷特带光谱的UVA和蓝光下会降低亚铁螯合酶活性及其蛋白。这些变化至少部分是由活性氧介导的。
