NADPH氧化酶的光驱激活

Light-driven activation of NADPH oxidases

NADPH氧化酶在多种细胞表达,激活后产生超氧阴离子或过氧化氢,调控各种细胞生理或病理活动.已知日光中的UVA波段,激活皮肤角质化细胞中的NOX1同工酶,以及肥大细胞中的NOX2同工酶.与复杂多亚基同工酶NOX1,NOX2相比,NOX5是单亚基同工酶,DUOX2是双亚基同工酶.NOX5含有所有NOX同工酶的吸光分子血红素,FAD,NADPH.NOX5同工酶中的NADPH,FAD皆为内源性光敏剂,吸收UVA后可通过Ⅱ型光动力作用产生单线态氧分子.现有文献认为,UVA可能可以激活所有NOX同工酶,导致其不可逆激活.在此光驱激活过程中,内源性光敏剂的Ⅱ型光动力作用,发挥关键作用.

NADPH oxidases(NOX)expressed in multiple cell types after activation produce superoxide or hydrogen peroxide to modulate several physiological and pathophysiological processes.The ultraviolet A(UVA)band in solar irradiation activates NOX1 in skin keratinocytes and NOX2 in mast cells.Whereas NOX1 and NOX2 are oligomeric,NOX5 is monomeric,and DUOX2 is dimeric.NOX5,like all other NOX isozymes,contains chromophores heme,NADPH,and FAD.Both NADPH and FAD are endogenous photosensitizers,which undergo type Ⅱ photodynamic action to produce singlet oxygen after absorption of UVA irradiation.In this review,we propose that UVA irradiation activates all NOX isoforms leading to their irreversible activation.Type Ⅱ photodynamic action of endogenous chromophores/photosensitizers plays a critical role in such UVA light-driven NOX activation.