title: Pancreatic and duodenal homeobox gene 1 induces hepatic dedifferentiation by suppressing the expression of CCAAT/enhancer-binding protein beta.
abstract: It is believed that adult tissues in mammals lack the plasticity needed to assume new developmental fates because of the absence of efficient pathways of dedifferentiation. However, the well-documented ability of the transcription factor pancreatic and duodenal homeobox gene 1 (PDX-1) to activate pancreatic lineage development and insulin production following ectopic expression in liver suggests a surprising degree of residual plasticity in adult liver cells. This study seeks a mechanistic explanation for the capacity of PDX-1 to endow liver cells with pancreatic characteristics and function. We demonstrate that PDX-1, previously shown to play an essential role in normal pancreatic organogenesis and pancreatic beta-cell function and to possess the potential to activate multiple pancreatic markers in liver, can also direct hepatic dedifferentiation. PDX-1 represses the adult hepatic repertoire of gene expression and activates the expression of the immature hepatic marker alpha-fetoprotein. We present evidence indicating that PDX-1 triggers hepatic dedifferentiation by repressing the key hepatic transcription factor CCAAT/enhancer-binding protein beta. Hepatic dedifferentiation is necessary though not sufficient for the activation of the mature pancreatic repertoire in liver.
  
  
  CONCLUSIONS
  Our study suggests a dual role for PDX-1 in liver: inducing hepatic dedifferentiation and activating the pancreatic lineage. The identification of dedifferentiation signals may promote the capacity to endow mature tissues in mammals with the plasticity needed for acquiring novel developmental fates and functions to be implemented in the field of regenerative medicine.
authors: The Endocrine Institute, Sheba Medical Center, Tel-Hashomer, Israel.
authors: Irit
authors: I
authors: Meivar-Levy
authors: Tamar
authors: T
authors: Sapir
authors: Shiraz
authors: S
authors: Gefen-Halevi
authors: Vered
authors: V
authors: Aviv
authors: Iris
authors: I
authors: Barshack
authors: Nicholas
authors: N
authors: Onaca
authors: Eytan
authors: E
authors: Mor
authors: Sarah
authors: S
authors: Ferber
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D002675:Child, Preschool; D004386:Duodenum / Q000166:cytology / Q000378:metabolism; D005260:Female; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D008297:Male; D010179:Pancreas / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D022782:CCAAT-Enhancer-Binding Protein-beta; D018398:Homeodomain Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein