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Nitric oxide maintains cell survival of Trichomonas vaginalis upon iron depletion.

Cheng WH, Huang KY, Huang PJ, Hsu JH, Fang YK, Chiu CH, Tang P - Parasit Vectors (2015)

Bottom Line: The free radical signaling molecules reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been proven to participate in iron deficiency in eukaryotes.We found that the inhibition of proteasome activity shortened the survival of iron-deficient cells compared with untreated iron-deficient cells.Surprisingly, the addition of arginine restored both NO level and the survival of proteasome-inhibited cells, suggesting that proteasome-derived NO is crucial for cell survival under iron-limited conditions.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kweishan, Taoyuan, Taiwan. m9701203@stmail.cgu.edu.tw.

ABSTRACT

Background: Iron plays a pivotal role in the pathogenesis of Trichomonas vaginalis, the causative agent of highly prevalent human trichomoniasis. T. vaginalis resides in the vaginal region, where the iron concentration is constantly changing. Hence, T. vaginalis must adapt to variations in iron availability to establish and maintain an infection. The free radical signaling molecules reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been proven to participate in iron deficiency in eukaryotes. However, little is known about the roles of these molecules in iron-deficient T. vaginalis.

Methods: T. vaginalis cultured in iron-rich and -deficient conditions were collected for all experiments in this study. Next generation RNA sequencing was conducted to investigate the impact of iron on transcriptome of T. vaginalis. The cell viabilities were monitored after the trophozoites treated with the inhibitors of nitric oxide (NO) synthase (L-NG-monomethyl arginine, L-NMMA) and proteasome (MG132). Hydrogenosomal membrane potential was measured using JC-1 staining.

Results: We demonstrated that NO rather than ROS accumulates in iron-deficient T. vaginalis. The level of NO was blocked by MG132 and L-NMMA, indicating that NO production is through a proteasome and arginine dependent pathway. We found that the inhibition of proteasome activity shortened the survival of iron-deficient cells compared with untreated iron-deficient cells. Surprisingly, the addition of arginine restored both NO level and the survival of proteasome-inhibited cells, suggesting that proteasome-derived NO is crucial for cell survival under iron-limited conditions. Additionally, NO maintains the hydrogenosomal membrane potential, a determinant for cell survival, emphasizing the cytoprotective effect of NO on iron-deficient T. vaginalis. Collectively, we determined that NO produced by the proteasome prolonged the survival of iron-deficient T. vaginalis via maintenance of the hydrogenosomal functions.

Conclusion: The findings in this study provide a novel role of NO in adaptation to iron-deficient stress in T. vaginalis and shed light on a potential therapeutic strategy for trichomoniasis.

No MeSH data available.


Related in: MedlinePlus

Scheme of the proposed model. In environments without sufficient iron availability, T. vaginalis activates the ubiquitin-proteasome system (UPS) to digest proteins and generate the amino acid arginine. It is likely that ADI, the enzyme with NO synthase activity in the hydrogenosome, utilizes arginine as the source for NO production [14, 32]. NO is crucial for the maintenance of hydrogenosomal function as well as antioxidant capacity. Both mechanisms protect T. vaginalis from iron deficiency-induced damage and prolong the survival of this parasite
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Fig6: Scheme of the proposed model. In environments without sufficient iron availability, T. vaginalis activates the ubiquitin-proteasome system (UPS) to digest proteins and generate the amino acid arginine. It is likely that ADI, the enzyme with NO synthase activity in the hydrogenosome, utilizes arginine as the source for NO production [14, 32]. NO is crucial for the maintenance of hydrogenosomal function as well as antioxidant capacity. Both mechanisms protect T. vaginalis from iron deficiency-induced damage and prolong the survival of this parasite

Mentions: In conclusion, we demonstrate, for the first time, that T. vaginalis utilized a NO-dependent regulatory network to survive in iron-deficient situations (Fig. 6). Once T. vaginalis encounters iron-limited environments, the protist generates more NO via proteasome-dependent pathway. The UPS-derived arginine is the substrate for NO production [33]. The generation of NO possibly takes place in the hydrogenosome since ADI, the enzyme with NO synthase activity, is found in this organelle [14, 32]. NO is a pivotal factor that modulates the hydrogenosomal membrane potential to protect cells from death. These mechanisms are vital for T. vaginalis to adapt to the continuous alternation of iron in the vaginal region, which is beneficial for establishment of an infection and parasitization.Fig. 6


Nitric oxide maintains cell survival of Trichomonas vaginalis upon iron depletion.

Cheng WH, Huang KY, Huang PJ, Hsu JH, Fang YK, Chiu CH, Tang P - Parasit Vectors (2015)

Scheme of the proposed model. In environments without sufficient iron availability, T. vaginalis activates the ubiquitin-proteasome system (UPS) to digest proteins and generate the amino acid arginine. It is likely that ADI, the enzyme with NO synthase activity in the hydrogenosome, utilizes arginine as the source for NO production [14, 32]. NO is crucial for the maintenance of hydrogenosomal function as well as antioxidant capacity. Both mechanisms protect T. vaginalis from iron deficiency-induced damage and prolong the survival of this parasite
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4513698&req=5

Fig6: Scheme of the proposed model. In environments without sufficient iron availability, T. vaginalis activates the ubiquitin-proteasome system (UPS) to digest proteins and generate the amino acid arginine. It is likely that ADI, the enzyme with NO synthase activity in the hydrogenosome, utilizes arginine as the source for NO production [14, 32]. NO is crucial for the maintenance of hydrogenosomal function as well as antioxidant capacity. Both mechanisms protect T. vaginalis from iron deficiency-induced damage and prolong the survival of this parasite
Mentions: In conclusion, we demonstrate, for the first time, that T. vaginalis utilized a NO-dependent regulatory network to survive in iron-deficient situations (Fig. 6). Once T. vaginalis encounters iron-limited environments, the protist generates more NO via proteasome-dependent pathway. The UPS-derived arginine is the substrate for NO production [33]. The generation of NO possibly takes place in the hydrogenosome since ADI, the enzyme with NO synthase activity, is found in this organelle [14, 32]. NO is a pivotal factor that modulates the hydrogenosomal membrane potential to protect cells from death. These mechanisms are vital for T. vaginalis to adapt to the continuous alternation of iron in the vaginal region, which is beneficial for establishment of an infection and parasitization.Fig. 6

Bottom Line: The free radical signaling molecules reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been proven to participate in iron deficiency in eukaryotes.We found that the inhibition of proteasome activity shortened the survival of iron-deficient cells compared with untreated iron-deficient cells.Surprisingly, the addition of arginine restored both NO level and the survival of proteasome-inhibited cells, suggesting that proteasome-derived NO is crucial for cell survival under iron-limited conditions.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kweishan, Taoyuan, Taiwan. m9701203@stmail.cgu.edu.tw.

ABSTRACT

Background: Iron plays a pivotal role in the pathogenesis of Trichomonas vaginalis, the causative agent of highly prevalent human trichomoniasis. T. vaginalis resides in the vaginal region, where the iron concentration is constantly changing. Hence, T. vaginalis must adapt to variations in iron availability to establish and maintain an infection. The free radical signaling molecules reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been proven to participate in iron deficiency in eukaryotes. However, little is known about the roles of these molecules in iron-deficient T. vaginalis.

Methods: T. vaginalis cultured in iron-rich and -deficient conditions were collected for all experiments in this study. Next generation RNA sequencing was conducted to investigate the impact of iron on transcriptome of T. vaginalis. The cell viabilities were monitored after the trophozoites treated with the inhibitors of nitric oxide (NO) synthase (L-NG-monomethyl arginine, L-NMMA) and proteasome (MG132). Hydrogenosomal membrane potential was measured using JC-1 staining.

Results: We demonstrated that NO rather than ROS accumulates in iron-deficient T. vaginalis. The level of NO was blocked by MG132 and L-NMMA, indicating that NO production is through a proteasome and arginine dependent pathway. We found that the inhibition of proteasome activity shortened the survival of iron-deficient cells compared with untreated iron-deficient cells. Surprisingly, the addition of arginine restored both NO level and the survival of proteasome-inhibited cells, suggesting that proteasome-derived NO is crucial for cell survival under iron-limited conditions. Additionally, NO maintains the hydrogenosomal membrane potential, a determinant for cell survival, emphasizing the cytoprotective effect of NO on iron-deficient T. vaginalis. Collectively, we determined that NO produced by the proteasome prolonged the survival of iron-deficient T. vaginalis via maintenance of the hydrogenosomal functions.

Conclusion: The findings in this study provide a novel role of NO in adaptation to iron-deficient stress in T. vaginalis and shed light on a potential therapeutic strategy for trichomoniasis.

No MeSH data available.


Related in: MedlinePlus