We have previously shown that the inhibition of fibroblast growth factor (FGF) signaling induced endodermal gene expression in the animal cap and caused the expansion of the endodermal mass in Xenopus embryos. However, we still do not know whether or not the alteration of FGF signaling controls embryonic cell fate, or when FGF signal blocking is required for endoderm formation in Xenopus. Here, we show that FGF signal blocking in embryonic cells causes their descendants to move into the endodermal region and to express endodermal genes. It is also interesting that blocking FGF signaling between fertilization and embryonic stage 10.5 promotes endoderm formation, but persistent FGF signaling blocking after stage 10.5 restricts endoderm formation and differentiation.
Animals ; Endoderm/drug effects/embryology/*metabolism ; Fibroblast Growth Factors/antagonists & inhibitors/genetics/*physiology ; Gene Expression Regulation, Developmental/drug effects ; In Situ Hybridization ; Pyrroles/administration & dosage/pharmacology ; Receptors, Fibroblast Growth Factor/genetics/physiology ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction/drug effects ; Xenopus Proteins/antagonists & inhibitors/genetics/*physiology ; Xenopus laevis/embryology/genetics/*physiology

BACKGROUNDFibroblast growth factor 21 (FGF21) is a new member of FGF super family that is an important endogenous regulator for systemic glucose and lipid metabolism. This study aimed to explore whether FGF21 reduces atherosclerotic injury and prevents endothelial dysfunction as an independent protection factor.

METHODSThe present study was designed to investigate the changes of FGF21 levels induced by oxidized-low density lipoprotein (ox-LDL), and the changes of apoptosis affected by regulating FGF21 expression. The FGF21 mRNA levels of cultured cardiac microvascular endothelial cells (CMECs) were determined by real time-PCR and the protein concentration in culture media was detected by enzyme-linked immunosorbent assay. We analyzed the different expression levels of untreated controls and CMECs incubated with ox-LDL, and the changes of CMECs apoptosis initiated by the enhancement or suppression of FGF21 levels.

RESULTSThe secretion levels of FGF21 mRNA and protein were significantly upregulated in CMECs incubated with ox-LDL. Furthermore, FGF21 levels increased by 200 µmol/L bezafibrate could reduce CMECs apoptosis, and inhibit FGF21 expression by shRNA induced apoptosis (P < 0.05).

CONCLUSIONSFGF21 may be a signal of injured target tissue, and may play physiological roles in improving the endothelial function at an early stage of atherosclerosis and in stopping the development of coronary heart disease.

Animals ; Apoptosis ; Bezafibrate ; pharmacology ; Cells, Cultured ; Coronary Artery Disease ; prevention & control ; Endothelial Cells ; physiology ; Fibroblast Growth Factors ; analysis ; antagonists & inhibitors ; genetics ; physiology ; Lipoproteins, LDL ; toxicity ; Male ; PPAR alpha ; physiology ; RNA, Messenger ; analysis ; Rats ; Rats, Wistar

OBJECTIVETo investigate the effect of extracellular signal-regulated kinase (ERK) signaling pathway on the endothelial differentiation of periodontal ligament stem cells (PDLSC).

METHODSHuman PDLSC was cultured in the medium with vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF) to induce endothelial differentiation. Endothelial inducing cells was incubated with U0126, a specific p-ERK1/2 inhibitor. PDLSC from one person were randomly divided into four groups: control group, endothelial induced group, endothelial induced+DMSO group and endothelial induced+U0126 group. The protein expression of the p-EKR1/2 was analyzed by Western blotting at 0, 1, 3, 6 and 12 hours during endonthelial induction. The mRNA expressions of CD31, VE-cadherin, and VEGF were detected by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) after a 7-day induction. The proportion of CD31(+) to VE-cadherin(+) cells was identified by flow cytometry, and the ability of capillary-like tubes formation was detected by Matrigel assay after a 14-day induction. The measurement data were statistically analyzed.

RESULTSPhosphorylated ERK1/2 protein level in PDLSC was increased to 1.24±0.12 and 1.03±0.24 at 1 h and 3 h respectively, during the endothelial induction (P<0.01). The mRNA expressions of CD31 and VEGF in induced+U0126 group were decreased to 0.09±0.18 and 0.49±0.17, which were both significantly different with those in induced group (P<0.05). The proportion of CD31(+) to VE-cadherin(+) cells of induced+U0126 group were decreased to 5.22±0.85 and 3.56±0.87, which were both significantly different with those in induced group (P<0.05). In Matrigel assay, the branching points, tube number and tube length were decreased to 7.0±2.7, 33.5±6.4, and (15 951.0±758.1) pixels, which were all significantly different with those in induced group (P<0.05).

CONCLUSIONSThe endothelial differentiation of PDLSC is positively regulated by ERK signaling pathway. Inhibition of ERK1/2 phosphorylation could suppress endothelial differentiation of PDLSC.

Antigens, CD ; genetics ; metabolism ; Butadienes ; pharmacology ; Cadherins ; genetics ; metabolism ; Cell Differentiation ; Endothelial Cells ; cytology ; physiology ; Enzyme Inhibitors ; pharmacology ; Extracellular Signal-Regulated MAP Kinases ; physiology ; Fibroblast Growth Factor 2 ; pharmacology ; Humans ; Mitogen-Activated Protein Kinase 3 ; antagonists & inhibitors ; metabolism ; Nitriles ; pharmacology ; Periodontal Ligament ; cytology ; metabolism ; Phosphorylation ; Platelet Endothelial Cell Adhesion Molecule-1 ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Random Allocation ; Signal Transduction ; Stem Cells ; cytology ; physiology ; Time Factors ; Vascular Endothelial Growth Factor A ; genetics ; metabolism ; pharmacology