AMP‐activated protein kinase α1 phosphorylates PHD2 to maintain systemic iron homeostasis

Abstract

Background Iron is essential for all mammalian life, and either a deficiency or excess of iron can cause diseases. AMP‐activated protein kinase (AMPK) is a critical regulator of metabolic homeostasis; however, it has not been established whether AMPK regulates iron metabolism. Methods Iron, hepcidin and ferroportin levels were examined in mice with global and hepatocyte‐specific knockout of AMPKα1 and AMPKα2. Primary AMPKα1 or AMPKα2 deleted hepatocytes were isolated and cultured in hypoxia condition to explore PHD2, HIF and hydroxylated HIF1α levels. We performed immunoprecipitation, in vitro AMPK kinase assay and site‐direct mutant assay to detect phosphorylation sites of PHD2. We also obtained liver tissues from patients with anaemia of chronic disease undergoing surgery, AMPKα1 and hydroxylated HIF1α levels were measured by immunohistochemical analysis. Results We found that mice with global deficiency of AMPKα1, but not AMPKα2, exhibited hypoferraemia as well as iron sequestration in the spleen and liver. Hepatocyte‐specific, but not myeloid‐specific, ablation of AMPKα1 also reduced serum iron levels in association with increased hepcidin and decreased ferroportin protein levels. Mechanistically, AMPKα1 directly phosphorylated prolyl hydroxylase domain‐containing (PHD)2 at serines 61 and 136, which suppressed PHD2‐dependent hydroxylation of hypoxia‐inducible factor (HIF)1α and subsequent regulation of hepatic hepcidin‐related iron signalling. Inhibition of PHD2 hydroxylation ameliorated abnormal iron metabolism in hepatic AMPKα1‐deficient mice. Furthermore, we found hepatic AMPKα/PHD2/HIFα/ hepcidin axes were highly clinically relevant to anaemia of chronic disease. Conclusion In conclusion, these observations suggest that hepatic AMPKα1 has an essential role in maintaining iron homeostasis by PHD2‐dependent regulation of hepcidin, thus providing a potentially promising approach for the treatment of iron disturbances in chronic diseases.

Silencing of topical proline hydroxylase domain 2 promotes the healing of rat diabetic wounds by phosphorylating AMPK

“…Although its most recognized role is that of a 'HIF regulator', we previously found that PHD2 can activate calmodulin-dependent protein kinase (CaMKK) β upstream of AMP-activated protein kinase (AMPK) and thereby protect against hypoxia-induced effects in cardiomyocytes; phosphorylated AMPK is a key factor in cell survival as it regulates energy metabolism [15,23]. This hypothesis has also been confirmed by other researchers studying systemic iron homeostasis [24]. Thus, we speculated that in diabetic wounds, PHD2 may promote wound repair by regulating AMPK.…”

“…It is well known that AMPK is the main regulator of metabolic homeostasis and as a cellular energy sensor, it is the guardian of the energy state of the cell [24,35]. AMPK is a key regulator of energy homeostasis, and coordinates adaptive responses in metabolic states depleting ATP such as hypoxia, ischemia/reperfusion, and exercise [36].…”

Study on the Effect of Oleic Acid-Induced Lipogenic Differentiation of Skeletal Muscle Satellite Cells in Yanbian Cattle and Related Mechanisms

“…The KEGG enrichment analysis revealed that the DEGs were mainly enriched in the AMPK and PPAR signaling pathways. The role of AMPK signaling pathway in regulating energy homeostasis is related to its effects on glucose and lipid metabolism, as well as on mitochondrial biogenesis and function [33]. The PPAR signaling pathway is mainly involved in regulating fatty acid metabolism, and cell proliferation and differentiation [34].…”

Research progress on the mechanism of angiogenesis in wound repair and regeneration

“…Notably, Cheng Wang and colleagues postulate the coexistence of PHD2 and AMPK within the same complex. AMPKα1 phosphorylates PHD2, rendering it inactive and curtailing the PHD2-mediated hydroxylation and degradation of HIF-1α ( Wang et al, 2022b ). The profound interrelation between AMPK-dependent and -independent regulation of HIF-1α, as well as the potential cross-linkage between these pathways, remains a terrain ripe for further exploration ( Figure 2 ).…”