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.
Dipartimento di Biologia Molecolare, Università degli studi di Siena, Via Fiorentina 1, 53100 Siena, Italy.
Alessio
A
Zippo
Alessandra
A
De Robertis
Monia
M
Bardelli
Federico
F
Galvagni
Salvatore
S
Oliviero
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