Originally identified as a gene up-regulated by iron overload in mouse liver, the HEPC gene encodes hepcidin, the first mammalian liver-specific antimicrobial peptide and potential key regulator of iron metabolism. Here we demonstrate that during rat liver development, amounts of HEPC transcripts were very low in fetal liver, strongly and transiently increased shortly after birth, and reappeared in adult liver. To gain insight into mechanisms that regulate hepatic expression of hepcidin, 5-flanking regions of human and mouse HEPC genes were isolated and analyzed by functional and DNA binding assays. Human and mouse HEPC promoterluciferase reporter vectors exhibited strong basal activity in hepatoma HuH-7 and mouse hepatocytes, respectively, but not in non-hepatic U-2OS cells. We found that CCAAT/enhancer-binding protein ␣ (C/EBP␣) and C/EBP␤ were respectively very potent and weak activators of both human and mouse promoters. In contrast, co-expression of hepatocyte nuclear factor 4␣ (HNF4␣) failed to induce HEPC promoter activity. By electrophoretic mobility shift assay we demonstrated that one putative C/EBP element found in the human HEPC promoter (؊250/؊230) predominantly bound C/EBP␣ from rat liver nuclear extracts. Hepatic deletion of the C/EBP␣ gene resulted in reduced expression of HEPC transcripts in mouse liver. In contrast, amounts of HEPC transcripts increased in liver-specific HNF4␣-null mice. Decrease of hepcidin mRNA in mice lacking hepatic C/EBP␣ was accompanied by iron accumulation in periportal hepatocytes. Finally, iron overload led to a significant increase of C/EBP␣ protein and HEPC transcripts in mouse liver. Taken together, these data demonstrate that C/EBP␣ is likely to be a key regulator of HEPC gene transcription and provide a novel mechanism for cross-talk between the C/EBP pathway and iron metabolism.

Key Words: cardiomyogenesis Ⅲ human mesenchymal stem cell Ⅲ immunologic tolerance Ⅲ myocardial infarction Ⅲ cell-based therapy A lthough embryonic stem cells 1 and induced pluripotent stem (iPS) cells 2 can be differentiated into cells of various organs, including cardiomyocytes, there are many underlining problems to overcome before clinical applications can be used, eg, tumorigenicity. 3 Autografts of iPS cells may not cause immunologic rejection; ironically, however, possible neoplasm formation would cause a serious problem because the neoplasm would not be rejected by the withdrawal of immunosuppressive agents. On the other hand, mesenchymal stem cells (MSCs) have recently been used for clinical application, and their safety and feasibility in cardiac stem cell-based therapy have been demonstrated. 4 Thus, MSCs are a more important cellular source for stem cell-based therapy from a practical point of view.The efficacy of human bone marrow-derived MSCs (BMMSCs) was still limited, 5 however, because of low efficiency for cardiomyogenic transdifferentiation. 6 We previously reported that non-marrow-derived mesenchymal cells had higher cardiomyogenic transdifferentiation efficiency, eg, menstrual blood-derived mesenchymal cells (MMCs), 7 umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), 8 and placental chorionic plate-derived mesenchymal cells (PCPCs). 9 These cells are thought to be used by an allograft; therefore, problems of immunologic rejection arise. However, an allograft may be superior to an autograft in several ways. Taking into account the background condition of the patient (eg, metabolic disease or age), Original received July 16, 2009; revision received April 14, 2010; accepted April 22, 2010 16 reported significant recovery of cardiac function by the rat amnion-derived cell transplantation in rat myocardial infarction (MI) model, however, they failed to show clear evidence of cardiomyogenic differentiation in vivo. Therefore, in the present study, we attempted to show: (1) the powerful cardiomyogenic transdifferentiation potential of our isolated hAMCs, and the beneficial effect of transplantation of hAMCs on cardiac function in vivo; (2) the induction of immunologic tolerance so that hAMCs can be a powerful allograftable stem cell source without either the administration of immunosuppressive agents or matching of MHC typing; (3) the mechanism of induction of tolerance; and (4) the close relationship between the cardiomyogenic transdifferentiation of mesenchymal cells and the process of immunologic tolerance. MethodsAn expanded Methods section is available in the Online Data Supplement at http://circres.ahajournals.org. Isolation and Culture of Human Amniotic Membrane-Derived Mesenchymal CellsHuman amniotic membrane was collected, with informed consent from individual patients, after delivery of a male neonate. The study was approved by the ethics committee of Keio University School of Medicine. The precise methods for culture have been described previously. 9,17 Detail is shown in...

Background-Hepatocyte nuclear factor 4α (HNF4α; NR2A1) is an orphan member of the nuclear receptor superfamily expressed in liver and intestine. While HNF4α expression is critical for liver function, its role in the gut and in the pathogenesis of inflammatory bowel disease (IBD) is unknown.