Allergens of the urushiol family promote mitochondrial dysfunction by inhibiting the electron transport at the level of cytochromes b and chemically modify cytochrome c1

BACKGROUND: Urushiols are pro-electrophilic haptens that cause severe contact dermatitis mediated by CD8+ effector T-cells and downregulated by CD4+ T-cells. However, the molecular mechanism by which urushiols stimulate innate immunity in the initial stages of this allergic reaction is poorly understood. Here we explore the sub-cellular mechanisms by which urushiols initiate the allergic response. RESULTS: Electron microscopy observations of mouse ears exposed to litreol (3-n-pentadecyl-10-enyl-catechol]) showed keratinocytes containing swollen mitochondria with round electron-dense inclusion bodies in the matrix. Biochemical analyses of sub-mitochondrial fractions revealed an inhibitory effect of urushiols on electron flow through the mitochondrial respiratory chain, which requires both the aliphatic and catecholic moieties of these allergens. Moreover, urushiols extracted from poison ivy/oak (mixtures of 3-n-pentadecyl-8,11,13 enyl/3-n-heptadecyl-8,11 enyl catechol) exerted a higher inhibitory effect on mitochondrial respiration than did pentadecyl catechol or litreol, indicating that the higher number of unsaturations in the aliphatic chain, stronger the allergenicity of urushiols. Furthermore, the analysis of radioactive proteins isolated from mitochondria incubated with 3H-litreol, indicated that this urushiol was bound to cytochrome c1. According to the proximity of cytochromes c1 and b, functional evidence indicated the site of electron flow inhibition was within complex III, in between cytochromes bL (cyt b566) and bH (cyt b562). CONCLUSION: Our data provide functional and molecular evidence indicating that the interruption of the mitochondrial electron transport chain constitutes an important mechanism by which urushiols initiates the allergic response. Thus, mitochondria may constitute a source of cellular targets for generating neoantigens involved in the T-cell mediated allergy induced by urushiols.

Construction of a lentivirus interfering vector targeting Cyc1 and its interfering efficiency in nasopharyngeal carcinoma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the expression of Cyc1 in nasopharyngeal carcinoma (NPC) and evaluate the interfering efficiency of a lentivirus interfering vector targeting Cyc1 in NPC cells.</p><p><b>METHODS</b>Microarray technique was used to examine the expression of Cyc1 in NPC tissues. Real-time PCR was utilized to confirm the high expression of Cyc1 in NPC tissues and NPC cell lines. The recombinant Cyc1 shRNA-expressing plasmid (pLentiU6/Cyc1-shRNA) was stably transfected into NPC cells, and the interfering efficiency against Cyc1 was evaluated by quantitative RT-PCR.</p><p><b>RESULTS</b>The result of microarray showed that Cyc1 was highly expressed in NPC tissues compared to noncancerous nasopharyngeal tissues, as confirmed by Real-time PCR. All of the 8 NPC cells showed a high expression of Cyc1, among which 5-8F cells showed the highest expression. Sequence analysis indicated that the recombinant plasmid pLentiU6/Cyc1-shRNA was successfully constructed and could significantly and stably suppress the expression of Cyc1 in NPC cells.</p><p><b>CONCLUSION</b>Cyc1 is highly expressed in NPC cells. The lentivirus vector constructed can markedly inhibit the expression of Cyc1 in NPC cells, which provides assistance in the investigation of the function and molecular mechanism of Cyc1 in NPC.</p>