MicroRNA Tae-miR1130p targets wheat ferroportin1 (TaFPN1) in the absence of iron-responsive element/iron-regulatory protein1 module

Abstract

Ferroportin (FPN) belongs to the Major Facilitator Superfamily of transporters and is a known iron (Fe) exporter in humans, with orthologues also present in plant species. Human FPN is subjected to multi-level regulation at transcriptional, post-transcriptional, and post-translational levels. How plant FPNs are regulated remains to be explored. In the current study, we have characterized wheat FPN1, a plasma-membrane localized protein, for its role in Fe homeostasis. A spatial-temporal expression analysis of wheat FPN1 suggested that its tissue-specific expression is differentially upregulated during Fe deficiency conditions. Unlike human FPN, plant FPN lacks the necessary sites for hepcidin binding, thereby emphasizing the need to explore the transcriptional/post-transcriptional mode of regulation. The lack of Iron Responsive Elements (IRE) in TaFPN1 promoter suggests no direct regulation through the Iron Regulatory Protein (IRP) mechanism like in humans. Further, to explore the miRNA-mediated regulation, we identified Fe-regulated tae-miR1130b-3p capable of targeting TaFPN1 under in-vivo conditions. Transcript expression of tae-miR1130b-3p negatively correlates with the TaFPN1. This alternative regulation pathway suggests a complex network of interactions governing the expression of genes involved in iron homeostasis, highlighting the intricacies of cellular regulatory mechanisms. Altogether, the work will unravel the cellular and physiological role of wheat FPN and contribute to a comprehensive understanding of plant iron homeostasis.