The latent transforming growth factor-beta-binding protein-1 promotes in vitro differentiation of embryonic stem cells into endothelium.
The latent transforming growth factor-beta-binding protein-1 (LTBP-1) belongs to a family of extracellular glycoproteins that includes three additional isoforms (LTBP-2, -3, and -4) and the matrix proteins fibrillin-1 and -2. Originally described as a TGF-beta-masking protein, LTBP-1 is involved both in the sequestration of latent TGF-beta in the extracellular matrix and the regulation of its activation in the extracellular environment. Whereas the expression of LTBP-1 has been analyzed in normal and malignant cells and rodent and human tissues, little is known about LTBP-1 in embryonic development. To address this question, we used murine embryonic stem (ES) cells to analyze the appearance and role of LTBP-1 during ES cell differentiation. In vitro, ES cells aggregate to form embryoid bodies (EBs), which differentiate into multiple cell lineages. We analyzed LTBP-1 gene expression and LTBP-1 fiber appearance with respect to the emergence and distribution of cell types in differentiating EBs. LTBP-1 expression increased during the first 12 d in culture, appeared to remain constant between d 12 and 24, and declined thereafter. By immunostaining, fibrillar LTBP-1 was observed in those regions of the culture containing endothelial, smooth muscle, and epithelial cells. We found that inclusion of a polyclonal antibody to LTBP-1 during EB differentiation suppressed the expression of the endothelial specific genes ICAM-2 and von Willebrand factor and delayed the organization of differentiated endothelial cells into cord-like structures within the growing EBs. The same effect was observed when cultures were treated with either antibodies to TGF-beta or the latency associated peptide, which neutralize TGF-beta. Conversely, the organization of endothelial cells was enhanced by incubation with TGF-beta 1. These results suggest that during differentiation of ES cells LTBP-1 facilitates endothelial cell organization via a TGF-beta-dependent mechanism.
Gualandris
A
A
Department of Cell Biology, New York University School of Medicine, New York, New York 10016-6497, USA.
Annes
J P
JP
Arese
M
M
Noguera
I
I
Jurukovski
V
V
Rifkin
D B
DB
D000818:Animals; D000906:Antibodies / Q000276:immunology; D015415:Biomarkers; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004727:Endothelium / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D015870:Gene Expression; D047908:Intracellular Signaling Peptides and Proteins; D053779:Latent TGF-beta Binding Proteins; D051379:Mice; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000502:physiology
D000906:Antibodies; D015415:Biomarkers; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C509032:LTBP1 protein, human; C509035:LTBP2 protein, human; D053779:Latent TGF-beta Binding Proteins; C509033:Ltbp1 protein, mouse; C509036:Ltbp2 protein, mouse; D016212:Transforming Growth Factor beta