Manganese promotes phorbol ester-induced interleukin-2 production via AP-1 activation in Jurkat T-cells

Divalent Metal Uptake and the Role of ZIP8 in Host Defense Against Pathogens

Manganese (Mn) and Zinc (Zn) are essential micronutrients whose concentration and location within cells are tightly regulated at the onset of infection. Two families of Zn transporters (ZIPs and ZnTs) are largely responsible for regulation of cytosolic Zn levels and to a certain extent, Mn levels, although much less is known regarding Mn. The capacity of pathogens to persevere also depends on access to micronutrients, yet a fundamental gap in knowledge remains regarding the importance of metal exchange at the host interface, often referred to as nutritional immunity. ZIP8, one of 14 ZIPs, is a pivotal importer of both Zn and Mn, yet much remains to be known. Dietary Zn deficiency is common and commonly occurring polymorphic variants of ZIP8 that decrease cellular metal uptake (Zn and Mn), are associated with increased susceptibility to infection. Strikingly, ZIP8 is the only Zn transporter that is highly induced following bacterial exposure in key immune cells involved with host defense against leading pathogens. We postulate that mobilization of Zn and Mn into key cells orchestrates the innate immune response through regulation of fundamental defense mechanisms that include phagocytosis, signal transduction, and production of soluble host defense factors including cytokines and chemokines. New evidence also suggests that host metal uptake may have long-term consequences by influencing the adaptive immune response. Given that activation of ZIP8 expression by pathogens has been shown to influence parenchymal, myeloid, and lymphoid cells, the impact applies to all mucosal surfaces and tissue compartments that are vulnerable to infection. We also predict that perturbations in metal homeostasis, either genetic- or dietary-induced, has the potential to impact bacterial communities in the host thereby adversely impacting microbiome composition. This review will focus on Zn and Mn transport via ZIP8, and how this vital metal transporter serves as a "go to" conductor of metal uptake that bolsters host defense against pathogens. We will also leverage past studies to underscore areas for future research to better understand the Zn-, Mn- and ZIP8-dependent host response to infection to foster new micronutrient-based intervention strategies to improve our ability to prevent or treat commonly occurring infectious disease.

Mitochondria are the target organelle of differentiation-inducing factor-3, an anti-tumor agent isolated from Dictyostelium discoideum [corrected]

Differentiation-inducing factor-3 (DIF-3), found in the cellular slime mold Dictyostelium discoideum, and its derivatives such as butoxy-DIF-3 (Bu-DIF-3) are potent anti-tumor agents. However, the precise mechanisms underlying the actions of DIF-3 remain to be elucidated. In this study, we synthesized a green fluorescent derivative of DIF-3, BODIPY-DIF-3, and a control fluorescent compound, Bu-BODIPY (butyl-BODIPY), and investigated how DIF-like molecules behave in human cervical cancer HeLa cells by using both fluorescence and electron microscopy. BODIPY-DIF-3 at 5–20 µ M suppressed cell growth in a dose-dependent manner, whereas Bu-BODIPY had minimal effect on cell growth. When cells were incubated with BODIPY-DIF-3 at 20 µM, it penetrated cell membranes within 0.5 h and localized mainly in mitochondria, while Bu-BODIPY did not stain the cells. Exposure of cells for 1–3 days to DIF-3, Bu-DIF-3, BODIPY-DIF-3, or CCCP (a mitochondrial uncoupler) induced substantial mitochondrial swelling, suppressing cell growth. When added to isolated mitochondria, DIF-3, Bu-DIF-3, and BOIDPY-DIF-3, like CCCP, dose-dependently promoted the rate of oxygen consumption, but Bu-BODIPY did not. Our results suggest that these bioactive DIF-like molecules suppress cell growth, at least in part, by disturbing mitochondrial activity. This is the first report showing the cellular localization and behavior of DIF-like molecules in mammalian tumor cells.