Effect of CI‐976 on ferritin secretion and viability in Aedes aegypti

Abstract

In mammals, iron taken into somatic cells is stored in ferritin or incorporated into iron containing proteins. Very little ferritin is found circulating in mammalian blood; most is retained in the cytoplasm. Ferritin is a multimer of 24 subunits of heavy and light chains. Female mosquitoes, such as Aedes aegypti (yellow fever mosquito), require a blood meal for oogenesis. Mosquitoes receive a potentially toxic level of iron in the blood meal which must be processed and stored to prevent oxidative damage. We are studying how mosquitoes and mosquito cells deal with this iron load. Iron treatment of A. aegypti larval CCL‐125 cells induces ferritin co‐localization with the Golgi apparatus and discrete vesicles within the cytoplasm. When these cells are exposed to high levels of iron, iron accumulates in the membranes. In contrast to mammalian cells, mosquito cells secrete ferritin into the culture medium in response to iron treatment. In addition, a 59Fe pulse‐chase experiment showed that both membrane and secreted ferritin were loaded with iron. To evaluate the effects of preventing ferritin secretion in the presence of iron load, we tested several known secretory inhibitors. Treatment of CCL‐125 cells with CI‐976 and iron disrupts ferritin secretion and decreases cell viability. Studies are underway to determine the effects of CI‐976 and RNAi on mosquito viability and fecundity following the iron load of a blood meal. This work was supported by funds from the National Institutes of Health (GM056812), the Agricultural Experiment Station, the College of Agriculture and Life Sciences and the BIO5 Institute for Collaborative Bioresearch at The University of Arizona.