Iron deficiency promotes bile acid deposition in an m6A-YTHDF2-CYP7A1 dependent mechanism

Background: Iron deficiency anemia is a major challenge in in both human health and animal husbandry. Disrupted bile acid metabolism is a key characteristic among people with anemia. However, effects and mechanisms of iron deficiency on bile acid metabolism remain unclear. N6-methyladenine (m6A) is the most abundant epigenetic modification, which can regulate various nutrient metabolism. This study aimed to investigate effect of iron deficiency on bile acid metabolism and elucidate its mechanism from the perspective of m6A methylation. Results: Iron deficiency (ID) destroyed liver morphology and ultrastructure in suckling piglet. Notably, ID induced moderate dilation of the endoplasmic reticulum and a reduction in mitochondrial number. At the metabolite level, ID significantly promoted bile acid deposition and reshaped bile acid profile. Specifically, ID decreased contents of GCA, CDCA, and 6-KetoLCA, while increasing levels of THDCA, T?MCA, DCA, GDCA, and TDCA (P < 0.05). At the molecular level, ID upregulated CYP7A1 expression to promoted bile acid deposition. Moreover, ID significantly decreased m6A content, and reduced expression of FTO and YTHDF2 (P < 0.05). M6A-seq data revealed an increase in m6A methylated peaks on CYP7A1 under ID condition. Importantly, RNA immunoprecipitation and stability experiments demonstrated YTHDF2 could bind and decrease stability of CYP7A1 (P < 0.05). Mechanistically, ID reduced YTHDF2 expression, thereby stabilizing CYP7A1 and driving bile acid accumulation. Conclusion: Iron deficiency induced bile acid deposition in an m6A-YTHDF2-CYP7A1 dependent manner, which further causes liver injury. Overall design: Twenty newborn male piglets (Duroc× [Landrace × Yorkshire]), each with a birth weight of approximately 1.72 kg, were selected from Kangle Agriculture and Animal Husbandry (Nantong, Jiangsu, China). Their body weight was within ± 0.5 standard deviation (SD) of the population mean weight. All piglets were kept in the farrowing room for two days after birth, where they were nursed freely from their sows. Subsequently, the suckling piglets were transferred to the new room and divided into two groups: negative control (NC) and iron deficiency (ID) group