Identification of Flk-1 target genes in vasculogenesis: Pim-1 is required for endothelial and mural cell differentiation in vitro.
The tyrosine kinase receptor fetal liver kinase 1 (Flk-1) plays a crucial role in vasculogenesis and angiogenesis, but its target genes remain elusive. Comparing Flk-1(+/+) with Flk-1(-/-) embryonic stem (ES) cells, we identified transcripts regulated by the vascular endothelial growth factor A (VEGF-A)/Flk-1 pathway at an early stage of their differentiation to endothelial and mural precursors. Further analysis of a number of these genes (Nm23-M1, Nm23-M2, Slug, Set, pp32, Cbp, Ship-1, Btk, and Pim-1) showed that their products were transiently up-regulated in vivo in endothelial cells (ECs) during angiogenesis of the ovary, and their mRNA was rapidly induced in vitro by VEGF-A in human umbilical cord vein endothelial cells (HUVECs). Functional analysis by RNA interference (RNAi) in ES cells induced to differentiate demonstrated that Pim-1 is required for their differentiation into ECs and smooth muscle cells (SMCs). In HUVECs, RNAi showed that Pim-1 is required in ECs for VEGF-A-dependent proliferation and migration. The identification of Flk-1 target genes should help in elucidating the molecular pathways that govern the vasculogenesis and angiogenesis processes.
Zippo
Alessio
A
Dipartimento di Biologia Molecolare, Università degli studi di Siena, Via Fiorentina 1, 53100 Siena, Italy.
De Robertis
Alessandra
A
Bardelli
Monia
M
Galvagni
Federico
F
Oliviero
Salvatore
S
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002478:Cells, Cultured; D017931:DNA Primers; D004730:Endothelium, Vascular / Q000166:cytology*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D018919:Neovascularization, Physiologic / Q000235:genetics / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D010053:Ovary / Q000098:blood supply; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D051573:Proto-Oncogene Proteins c-pim-1; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000172:deficiency* / Q000235:genetics / Q000502:physiology*
D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D040281:Vascular Endothelial Growth Factor Receptor-1; C496634:PIM1 protein, human; C496636:Pim1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D051573:Proto-Oncogene Proteins c-pim-1