title: Lymphatic endothelial cell identity is reversible and its maintenance requires Prox1 activity.
abstract: The activity of the homeobox gene Prox1 is necessary and sufficient for venous blood endothelial cells (BECs) to acquire a lymphatic endothelial cell (LEC) fate. We determined that the differentiated LEC phenotype is a plastic, reprogrammable condition that depends on constant Prox1 activity for its maintenance. We show that conditional down-regulation of Prox1 during embryonic, postnatal, or adult stages is sufficient to reprogram LECs into BECs. Consequently, the identity of the mutant lymphatic vessels is also partially reprogrammed as they acquire some features typical of the blood vasculature. siRNA-mediated down-regulation of Prox1 in LECs in culture demonstrates that reprogramming of LECs into BECs is a Prox1-dependent, cell-autonomous process. We propose that Prox1 acts as a binary switch that suppresses BEC identity and promotes and maintains LEC identity; switching off Prox1 activity is sufficient to initiate a reprogramming cascade leading to the dedifferentiation of LECs into BECs. Therefore, LECs are one of the few differentiated cell types that require constant expression of a certain gene to maintain their phenotypic identity.
authors.affiliation: Department of Genetics and Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Johnson
authors.forename: Miriam E
authors.initials: ME
authors.lastname: Dillard
authors.forename: Peter
authors.initials: P
authors.lastname: Baluk
authors.forename: Donald M
authors.initials: DM
authors.lastname: McDonald
authors.forename: Natasha L
authors.initials: NL
authors.lastname: Harvey
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Frase
authors.forename: Guillermo
authors.initials: G
authors.lastname: Oliver
mesh_terms: D000818:Animals; D054337:Cell Dedifferentiation / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D015536:Down-Regulation; D042783:Endothelial Cells / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics; D051379:Mice; D010641:Phenotype; D034741:RNA, Small Interfering / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000235:genetics; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: D018398:Homeodomain Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein