Differential roles of nitric oxide synthases in regulation of ultraviolet B light-induced apoptosis

作者：Liu Wei; Wu Shiyong^*

来源：Nitric Oxide-Biology and Chemistry, 2010, 23(3): 199-205.

DOI：10.1016/j.niox.2010.06.003

• UVB
• cNOS
• Nitric oxide
• Caspase 3
• Apoptosis

Ultraviolet B light (UVB) activates nitric oxide synthase(s) (NOSs) and nitric oxide (No(center dot)) production, which plays a role in regulation of apoptosis. However, the role of NO in UVB-induced apoptosis remains controversial. In this study, we analyzed expression and activation of constitutive NOSs (cNOSs) and their roles in UV-induced apoptosis of HaCaT keratinocytes. Our data showed that the expression of neuronal NOS (nNOS) was increased while endothelial NOS (eNOS) was uncoupled in the early phase (0-6 h) post-UVB. The expression of both cNOSs peaked at 12 h post-UVB and NO was transiently elevated with 30 min and then steadily rose from 6 to 18 h post-UVB. The expression of iNOS was detected at 6 h post-UVB and then sturdily increased. Inhibition of cNOSs with I.-NAME reduced the inducibility of NO in the early and late phases of irradiation. Along with the eNOS uncoupling, an increased level of peroxynitrite (ONOO(-)) was detected in the early phase, but not in the late phase post-UVB. Inhibition of cNOSs reduced the production of ONOO(-) in the early time, but led to an increase of ONOO(-) in the late time after UVB-irradiation. The results indicate that cNOSs regulate NO center dot/ONOO(-) imbalance after UVB-irradiation. Our data suggested that the activation of cNOSs in the early phase post-UVB leads to NO center dot/ONOO(-) imbalance and promotes apoptosis via a caspase 3-independent pathway. The elevation of NO in the late phase of UVB-irradiation is mainly produced by inducible NOS (iNOS). However, cNOSs also contribute to the NO production and to maintain a higher NO center dot/ONOO(-) ratio, which reduces caspase 3 activity and protects cells from UVB-induced apoptosis. Published by Elsevier Inc.

• 出版日期2010-11-1