Leishmania donovaniinhibits ferroportin translation by modulating FBXL5-IRP2 axis for its growth within host macrophages

Abstract

Hepcidin mediated ferroportin (Fpn) degradation in macrophages is a well adopted strategy to limit iron availability towards invading pathogens. Leishmania donovani (LD), a protozoan parasite, resides within macrophage and competes with host for availing iron. Using in vitro and in vivo model of infection, we reveal that LD decreases Fpn abundance in host macrophages by hepcidin independent mechanism. Unaffected level of Fpn-FLAG in LD infected J774 macrophage confirms that Fpn down-regulation is not due its degradation. While increased Fpn mRNA but decreased protein expression in macrophages suggests blocking of Fpn translation by LD infection that is confirmed by S-methionine labelling assay. We further reveal that LD blocks Fpn translation by induced binding of iron regulatory proteins (IRPs) to the iron responsive element present in its 5'UTR. Supershift analysis provides evidence of involvement of IRP2 particularly during in vivo infection. Accordingly, a significant increase in IRP2 protein expression with simultaneous decrease in its stability regulator F-box and leucine-rich repeat Protein 5 (FBXL5) is detected in splenocytes of LD-infected mice. Increased intracellular growth due to compromised expressions of Fpn and FBXL5 by specific siRNAs reveals that LD uses a novel strategy of manipulating IRP2-FBXL5 axis to inhibit host Fpn expression.

Effect of Cisplatin on Renal Iron Homeostasis Components: Implication in Nephropathy

“…Animals lacking IRP1 are unable to repress ferritin synthesis fully in the kidney during iron deficiency, implying that mainly, IRP1 contributes to the regulation of iron metabolism in the kidney, , whereas in general, IRP2 is over-expressed in different cancer cells and plays a critical role in tumor growths. − Thus, the ability of cisplatin in forming a complex mainly with IRP2 in altering IRE–IRP targets in different cancer cells may not be effective in renal cells due to the negligible abundance of IRP2. It is to be noted that IRP2 could not be detected in HEK293 cells in an earlier report, while we could detect only a negligible amount (Figure ), although the same antibody was useful in detecting IRP2 in different cell types (Figure S1) as we reported earlier. − …”

“…It is to be noted that IRP2 could not be detected in HEK293 cells in an earlier report, 29 while we could detect only a negligible amount ( Figure 3 ), although the same antibody was useful in detecting IRP2 in different cell types ( Figure S1 ) as we reported earlier. 38 − 40 …”

Baseline iron status and presence of anaemia determine the course of systemic Salmonella infection following oral iron supplementation in mice

“…Of note, when comparing hepcidin levels and macrophage FPN1 expression between Std and Anm groups, it appears that FPN1 is regulated not only by circulating hepcidin levels, but additionally via translational regulation involving iron regulatory proteins or pathogen mediated regulatory circuits [ 33 , 64 , 65 ]. Further, FPN1 regulation underlies a dynamic process depending on the time point of investigation and the mode of Salmonella infection.…”

Iron trafficking in patients with Indian Post kala-azar dermal leishmaniasis

“…Ferroportin (Fpn) is an established mammalian iron exporter whose regulation is critical for iron homeostasis, and its alterations can translate into iron deficiency or iron overload. It has been proposed that to increase the availability of iron, host cell derived hepcidin promotes the degradation of Fpn which translates into increased availability of iron during infections with L. amazonensis [56,57], and has been substantiated in patients with VL [31]. However, in L. donovani models of infection where despite the levels of Hepcidin being raised, the mRNA expression of Fpn too was elevated [57].…”

“…It has been proposed that to increase the availability of iron, host cell derived hepcidin promotes the degradation of Fpn which translates into increased availability of iron during infections with L. amazonensis [56,57], and has been substantiated in patients with VL [31]. However, in L. donovani models of infection where despite the levels of Hepcidin being raised, the mRNA expression of Fpn too was elevated [57]. Similarly, in PKDL cases an increased mRNA expression of Fpn was demonstrated ( Fig 3B); however it should be confirmed at a translational level.…”