Project description:Iron deficiency is a common nutritional deficit that can lead to organ damage or dysfunction. Research is increasingly linking iron deficiency to dysfunction of bone metabolism, although the exact mechanisms remain unclear. Some studies suggest that iron-dependent methylation-erasing enzyme activity regulates cell proliferation and differentiation under physiological or pathological conditions. Whether iron deficiency inhibits the activation of quiescent mesenchymal stem cells (MSCs) by affecting histone demethylase activity is unclear. In our study, we discovered that KDM4D plays a pivotal role in the activation of quiescent MSCs. Under conditions of iron deficiency, the H3K9me3 demethylase activity of KDM4D significantly decreased. This change led to increased heterochromatin with H3K9me3 near the PIK3R3 promoter, hindering the expression of PIK3R3. Subsequently, the activation of quiescent MSCs was inhibited via the PI3K-Akt-Foxo1 pathway. Iron-deficient mice exhibited significantly inhibited bone marrow MSC activation and reduced bone mass compared to normal mice. Modulating the PI3K-Akt-Foxo1 pathway could reverse iron deficiency-induced bone loss.
Project description:Iron deficiency is a common nutritional deficit that can lead to organ damage or dysfunction. Research is increasingly linking iron deficiency to dysfunction of bone metabolism, although the exact mechanisms remain unclear. Some studies suggest that iron-dependent methylation-erasing enzyme activity regulates cell proliferation and differentiation under physiological or pathological conditions. Whether iron deficiency inhibits the activation of quiescent mesenchymal stem cells (MSCs) by affecting histone demethylase activity is unclear. In our study, we discovered that KDM4D plays a pivotal role in the activation of quiescent MSCs. Under conditions of iron deficiency, the H3K9me3 demethylase activity of KDM4D significantly decreased. This change led to increased heterochromatin with H3K9me3 near the PIK3R3 promoter, hindering the expression of PIK3R3. Subsequently, the activation of quiescent MSCs was inhibited via the PI3K-Akt-Foxo1 pathway. Iron-deficient mice exhibited significantly inhibited bone marrow MSC activation and reduced bone mass compared to normal mice. Modulating the PI3K-Akt-Foxo1 pathway could reverse iron deficiency-induced bone loss.
Project description:Iron transporters are essential for maintaining cellular iron homeostasis. Among them, SLC22A17 mediates lipocalin-2 (LCN-2)-dependent iron transport, but its precise role in the brain remains unclear. Here, we show that Slc22a17 is critical for postnatal neurogenesis by regulating hippocampal iron balance. Conditional knockout of Slc22a17 in the murine brain causes early postnatal lethality, growth retardation, neural stem cell apoptosis, and cognitive deficits, largely due to oxidative stress from iron overload. Mechanistically, Slc22a17 interacts with p62 to modulate Nrf2 activity. Its loss aberrantly activates the Nrf2/HO-1 pathway, disrupting iron efflux and promoting accumulation of reactive oxygen species (ROS). These findings establish Slc22a17 as a key regulator of neuronal development and a potential therapeutic target for neurological disorders linked to iron dysregulation.
Project description:Iron is an essential element for several cellular processes and recent evidence highlighted its role in regulating the function of hematopoietic stem cells (HSCs). When in excess it reduces quiescence and self-renewal, however, whether and how iron influences HSC metabolism is still unknown. Here, we show that intracellular iron overload (IO) impairs mitochondrial fitness and bioenergetics, inducing metabolic rewiring in HSCs. In three models of IO, HSCs accumulate mitochondria with elevated reactive oxygen species (ROS), low membrane potential and reduced oxidative phosphorylation (OXPHOS). IO HSCs proliferate despite low mitochondrial activity and OXPHOS and rely on glycolysis for energy production. Notably, restoration of mitochondrial function by targeting in vivo iron and mitochondrial ROS improved the quiescence and self-renewal of IO HSCs. Our results unravel the critical interplay between iron, ROS and mitochondria in HSCs, disclosing that iron acts as an extrinsic regulator of HSC metabolic programs.
