MiRNA-616 aggravates the progression of bladder cancer by regulating cell proliferation, migration and apoptosis through downregulating SOX7.

OBJECTIVE: To investigate the regulatory effect of microRNA-616 (miRNA-616) on cellular behaviors of bladder cancer and the potential mechanism. PATIENTS AND METHODS: The expressions of miRNA-616 and SOX7 in bladder cancer tissues and cell lines were examined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The relationship between miRNA-616 and SOX7 was assessed through Dual-Luciferase Reporter Gene Assay. The regulatory effects of miRNA-616 and SOX7 on cellular behaviors of bladder cancer were evaluated through cell counting kit-8 (CCK-8), colony formation, transwell migration assay, and flow cytometry. RESULTS: MiRNA-616 was upregulated, whereas SOX7 was downregulated in bladder cancer tissues and cell lines. The silence of miRNA-616 attenuated the proliferative and migratory abilities, arrested cell cycle progression in the G2 phase, and stimulated apoptosis in UMUC3 and T24 cells. SOX7 was the target gene of miRNA-616, and its level was negatively regulated by miRNA-616. The knockdown of SOX7 enhanced the proliferative and migratory abilities, and attenuated apoptosis of bladder cancer cells. CONCLUSIONS: MiRNA-616 accelerates bladder cancer cells to proliferate and migrate and inhibits apoptosis by downregulating SOX7. MiRNA-616/SOX7 may be potential therapeutic targets for bladder cancer.

Endocardium differentiation through Sox17 expression in endocardium precursor cells regulates heart development in mice.

The endocardium is the endothelial component of the vertebrate heart and plays a key role in heart development. Where, when, and how the endocardium segregates during embryogenesis have remained largely unknown, however. We now show that Nkx2-5+ cardiac progenitor cells (CPCs) that express the Sry-type HMG box gene Sox17 from embryonic day (E) 7.5 to E8.5 specifically differentiate into the endocardium in mouse embryos. Although Sox17 is not essential or sufficient for endocardium fate, it can bias the fate of CPCs toward the endocardium. On the other hand, Sox17 expression in the endocardium is required for heart development. Deletion of Sox17 specifically in the mesoderm markedly impaired endocardium development with regard to cell proliferation and behavior. The proliferation of cardiomyocytes, ventricular trabeculation, and myocardium thickening were also impaired in a non-cell-autonomous manner in the Sox17 mutant, likely as a consequence of down-regulation of NOTCH signaling. An unknown signal, regulated by Sox17 and required for nurturing of the myocardium, is responsible for the reduction in NOTCH-related genes in the mutant embryos. Our results thus provide insight into differentiation of the endocardium and its role in heart development.

Directed differentiation of human induced pluripotent stem cells into mature stratified bladder urothelium.

For augmentation or reconstruction of urinary bladder after cystectomy, bladder urothelium derived from human induced pluripotent stem cells (hiPSCs) has recently received focus. However, previous studies have only shown the emergence of cells expressing some urothelial markers among derivatives of hiPSCs, and no report has demonstrated the stratified structure, which is a particularly important attribute of the barrier function of mature bladder urothelium. In present study, we developed a method for the directed differentiation of hiPSCs into mature stratified bladder urothelium. The caudal hindgut, from which the bladder urothelium develops, was predominantly induced via the high-dose administration of CHIR99021 during definitive endoderm induction, and this treatment subsequently increased the expressions of uroplakins. Terminal differentiation, characterized by the increased expression of uroplakins, CK13, and CK20, was induced with the combination of Troglitazone + PD153035. FGF10 enhanced the expression of uroplakins and the stratification of the epithelium, and the transwell culture system further enhanced such stratification. Furthermore, the barrier function of our urothelium was demonstrated by a permeability assay using FITC-dextran. According to an immunohistological analysis, the stratified uroplakin II-positive epithelium was observed in the transwells. This method might be useful in the field of regenerative medicine of the bladder.

The role of SOX18 in bladder cancer and its underlying mechanism in mediating cellular functions.

AIMS: SRY-box 18 (SOX18) is a transcription factor known for its role in regulating cell differentiation and lymphatic and blood vessel development. It has been reported that SOX18 was involved in various diseases, including cancer. This study aimed to explore the significance and biological function of SOX18 in bladder cancer (BCa). MATERIALS AND METHODS: SOX18 expression in BCa and normal tissues was analyzed by immunohistochemistry, and SOX18 expression in BCa cell lines was quantified by western blotting and quantitative real-time PCR. The role of SOX18 on the proliferation, migration and invasion of BCa cells was explored by CCK-8 and transwell invasion assays in vitro. Cell cycle was measured by flow cytometry assays. Western blotting and qRT-PCR were performed to investigate the potential mechanisms by which SOX18 leads to tumor progression. KEY FINDINGS: SOX18 was significantly upregulated in BCa and its expression was associated with clinical features of patients with BCa. Our data demonstrated that SOX18 promoted cell proliferation via accelerating cell cycle and by regulating c-Myc and Cyclin D1, promoted cell invasion via upregulation of MMP-7. Moreover, phosphorylation of c-Met and Akt regulated by SOX18 was identified to be involved in the process of cell migration and invasion, indicating the vital role of SOX18 in the metastasis of BCa. SIGNIFICANCE: Our data demonstrated a cancer-promoting effect of SOX18 in BCa, revealed the potential mechanisms of SOX18 in mediating cellular functions, and indicated that SOX18 may serve as a promising progression and prognostic biomarker and a therapeutic target for BCa.

Heterogeneous expression and biological function of SOX18 in osteosaroma.

Osteosaroma (OS) is a primary bone malignancy and is associated with high morbidity. Sex determining region Y-box 18 (SOX18) is identified overexpressed in OS. However, the molecular mechanism underlying the biological function of SOX18 in OS is still unclear. The aim of the current study was to determine the SOX18 expression in patients with OS and its effect on tumor cell malignant phenotypes. Our results showed that SOX18 was overexpressed in OS patients from both E-MEXP-3628 database and independent samples from our hospital and in OS cell lines. SOX18 silencing significantly induced G0-G1 phase cell cycle arrest and apoptosis and inhibited U-2OS cell migration and invasion and cell growth both in vitro and in vivo. However, SOX18 overexpression remarkably promoted 143B cell proliferation, migration and invasion and inhibited cell cycle arrest and apoptosis. The protein expression levels of p53, p21, Bax, Bcl-2, and Caspase-3 were also regulated by SOX18. Moreover, SOX18 was found negative correlated with the expression of HERC1, HER2, HERC3, HERC4, HERC5, and HERC6 in OS patients and in OS cells, with the most significant correlation detected in HERC2 expression, which was following found interacted with SOX18 in OS cells. Taken together, our results suggest that SOX18 is overexpressed in OS and plays an important role in proliferation, apoptosis, migration and invasion of OS cells, and may provide a novel and promising thera-peutic strategy for OS.

Genome-wide transcriptomics analysis identifies sox7 and sox18 as specifically regulated by gata4 in cardiomyogenesis.

The transcription factors GATA4, GATA5 and GATA6 are important regulators of heart muscle differentiation (cardiomyogenesis), which function in a partially redundant manner. We identified genes specifically regulated by individual cardiogenic GATA factors in a genome-wide transcriptomics analysis. The genes regulated by gata4 are particularly interesting because GATA4 is able to induce differentiation of beating cardiomyocytes in Xenopus and in mammalian systems. Among the specifically gata4-regulated transcripts we identified two SoxF family members, sox7 and sox18. Experimental reinstatement of gata4 restores sox7 and sox18 expression, and loss of cardiomyocyte differentiation due to gata4 knockdown is partially restored by reinstating sox7 or sox18 expression, while (as previously reported) knockdown of sox7 or sox18 interferes with heart muscle formation. In order to test for conservation in mammalian cardiomyogenesis, we confirmed in mouse embryonic stem cells (ESCs) undergoing cardiomyogenesis that knockdown of Gata4 leads to reduced Sox7 (and Sox18) expression and that Gata4 is also uniquely capable of promptly inducing Sox7 expression. Taken together, we identify an important and conserved gene regulatory axis from gata4 to the SoxF paralogs sox7 and sox18 and further to heart muscle cell differentiation.

Improvement of hepatogenic differentiation of iPS cells on an aligned polyethersulfone compared to random nanofibers.

The application of stem cells holds great promises in cell and tissue transplants. This study was designed to compare the hepatogenic differentiation of iPSCs on aligned PES/COL versus random. Aligned and random PES/COL nanofibrus scaffolds were fabricated by electrospining and their surface modified through plasma treatment and collagen coating. The scaffolds were characterized using scanning electron microscopy (SEM) and ATR-FTIR. Morphology and biochemical activities of the differentiated hepatocyte-like cells (HLCs) were examined after 5 and 20 days of differentiation. Real-Time RT-PCR and ICC showed no significant difference in the mRNA and protein levels of two important definitive endoderm specific markers, including Sox17 and Foxa2 between two scaffolds. However, Real-Time RT-PCR analysis indicated an increase in the expression of Cyp7A1 gene over the period of the differentiation procedure on the aligned nanofibers but there was no difference in other genes such as Albumin and CK19. Moreover, comparison of hepatogenic differentiation evaluated by Albumin production in conditioned media of HLCs differentiated on aligned PES/COL, showed increase expression of these markers after 20 days compared to that of the random nanofibers. Taken together, the results of this study may indicate that aligned PES/COL nanofibrous scaffolds can improve terminal differentiation of HLCs from iPSCs.

A sequential EMT-MET mechanism drives the differentiation of human embryonic stem cells towards hepatocytes.

Reprogramming has been shown to involve EMT-MET; however, its role in cell differentiation is unclear. We report here that in vitro differentiation of hESCs to hepatic lineage undergoes a sequential EMT-MET with an obligatory intermediate mesenchymal phase. Gene expression analysis reveals that Activin A-induced formation of definitive endoderm (DE) accompanies a synchronous EMT mediated by autocrine TGFß signalling followed by a MET process. Pharmacological inhibition of TGFß signalling blocks the EMT as well as DE formation. We then identify SNAI1 as the key EMT transcriptional factor required for the specification of DE. Genetic ablation of SNAI1 in hESCs does not affect the maintenance of pluripotency or neural differentiation, but completely disrupts the formation of DE. These results reveal a critical mesenchymal phase during the acquisition of DE, highlighting a role for sequential EMT-METs in both differentiation and reprogramming.

Decreased expression of SOX7 induces cell proliferation and invasion and correlates with poor prognosis in oral squamous cell carcinoma.

BACKGROUND: SOX7, a member of the SOX family of transcription factors, acts as a tumor suppressor in multiple cancers. Downregulation of SOX7 has been reported in advanced tumors and correlates with poor prognosis. The aims of this study were to investigate the effects of SOX7 on cell proliferation, invasion, and colony formation in oral squamous cell carcinoma (OSCC) cells and to evaluate the effectiveness of SOX7 protein as a prognostic indicator for OSCC patients. METHODS: oral squamous cell carcinoma (OSCC) cell lines were treated with SOX7 small interfering RNA or SOX7 peptide, and their effects on cell proliferation, invasiveness, and colony formation were investigated by proliferation, in vitro invasion, and clonogenic assays. SOX7 protein expression in OSCC and normal oral mucosal tissues was examined by immunohistochemistry. Associations between SOX7 protein expression and clinicopathological parameters of OSCC patients were statistically analyzed. RESULTS: SOX7 silencing-induced cell proliferation and invasion in SCC-4 cells. SOX7 peptide treatment inhibited cell proliferation, colony formation, and invasion in SCC-9 and SCC-25 cells. Expression of SOX7 protein was decreased in OSCC tissues compared with normal oral mucosal tissues (P<.001). Negative SOX7 expression in patients with OSCC was significantly associated with positive lymph node metastasis (P=.041), advanced TNM stage (P=.024), and poor prognosis (P=.017). CONCLUSIONS: These results suggest that SOX7 inhibits cell proliferation, colony formation, and invasion in OSCC as a tumor suppressor and that negative SOX7 expression could be a poor prognostic indicator for patients with OSCC.

Generation of enhanced definitive endoderm from human embryonic stem cells under an albumin/insulin-free and chemically defined condition.

AIM: To enhance survival and generation of definitive endoderm cells from human embryonic stem cells in a simple and reproducible system. MAIN METHODS: Definitive endoderm (DE) differentiation from human embryonic stem cells (hESCs) was induced under a chemical-defined condition withdrawn insulin supplement and serum albumin. We dissected influence of "alternative growth factors", WNT3A, BMP4 and bFGF in activin A-driven differentiation by detection of DE-associated genes expression and cell viability. Expression of DE-associated SOX17 and FOXA2 genes was analyzed by real time reverse transcription polymerase chain reaction (RT-PCR) and Western blot assays. Quantitative evaluation of DE efficiency was performed by flow cytometry analysis of CXCR4-expressed cell population. Cell viability during DE differentiation was analyzed by an Annexin V/PI double staining test. KEY FINDINGS: Supplementation with WNT3A, BMP4 or bFGF promoted DE generation in a dose- and time-dependent manner. Cell apoptosis elicited by activin A was significantly ameliorated by a cocktail with WNT3A, BMP4 and bFGF. This allowed for sustained cell viability without insulin-containing supplements, thereby indirectly improving the efficiency of DE generation. Therefore, the cocktail containing is optimal for efficient DE generation in the presence of activin A and an insulin/albumin-free condition. SIGNIFICANCE: This optimal condition facilitates the balance between the productivity and the viability maintenance, and could be valuable for mass production of DE with minimal variation.

MicroRNAs modulate the expression of the SOX18 transcript in lung squamous cell carcinoma.

Recent statistics show that lung cancer is the second most common malignant tumor in the world (14% of all cancers in the USA), both in terms of morbidity and mortality. The mortality of this type of tumor shows an increasing trend (28% for men and 26% for women). Lung squamous cell carcinoma (LSCC) is the second­largest histological subtype of non­small cell lung cancers (NSCLCs) after adenocarcinoma. SRY­related HMG­box 18 (SOX18) protein is an important transcription factor involved in the development of the cardiovascular system and the lymphatic ducts. In addition, it was observed that SOX18 functions in wound healing processes and the development of atherosclerosis. Likewise, an increased level of this protein was found in melanomas and malignant pancreatic, stomach and breast tumors. Furthermore, high expression of SOX18 in gastric cancer stromal cells was found to be associated with a poor patient prognosis. In the present study, we analyzed the expression of the SOX18 protein and the mRNA level in postoperative samples of LSCC and non­malignant lung tissues (NMLTs), and a disparity in both levels was observed. Because of the fact that microRNAs (miRNAs) play important roles in the initiation and progression of lung cancer, the main aim of this study was to identify the miRNAs that interact with the SOX18 transcript in NSCLC cases. SOX18 mRNA expression level was significantly lower in the LSCC tissues than that noted in the NMLTs (p<0.01). However, protein levels were higher in the LSCC cases compared to these levels in the NMLTs (p<0.0001). We showed that miR­7a and miR­24­3p were expressed more highly in the NMLTs than levels in the LSCC samples, and that they could be switched off in lung cancer tissue. Additionally, correlations between RQ­values of SOX18 in NMLTs and LSCC samples (r=0.43, p=0.019), and between miR­7a and miR24­3p in NMLT cases (r=0.4, p=0.057) as well as in the LSCC samples (r=0.51, p=0.012) were noted. In conclusion, miRNAs interact with the mRNA of the SOX18 gene, but the mechanism by which they could be inhibited in cancer cells requires further examination.

MicroRNA-452 promotes stem-like cells of hepatocellular carcinoma by inhibiting Sox7 involving Wnt/ß-catenin signaling pathway.

The decrease of microRNA-452 (miR-452) in gliomas promoted stem-like features and tumorigenesis. However, the role of miR-452, especially in regulating cancer stem cells (CSCs) in hepatocellular carcinoma (HCC) remains ambiguous. We enriched stem-like HCC cells by serial passages of hepatospheres with chemotherapeutic agents. Stem-like characteristics including the capabilities of chemo-resistance, stemness-related gene expression profiling, self-renewal, tumorigenicity and metastasis formation were detected. MiR-452 was markedly increased in the chemo-resistant hepatospheres and human HCC tissues. and the overexpression of miR-452 in HCC patients predicted poor overall survival. MiR-452 significantly promoted stem-like characteristics in vitro and in vivo. Further, Sox7 was identified as the direct target of miR-452, which could physically bind with ß-catenin and TCF4 in the nucleus and then inhibit the activity of Wnt/ß-catenin signaling pathway. Finally, the combined chemotherapy of doxorubicin and all-trans retinoic acid (ATRA) showed dramatically efficiency in suppressing HCC metastasis. These data suggested that miR-452 promoted stem-like traits of HCC, which might be a potential therapeutic target for HCC. The combination of doxorubicin and ATRA might be a promising therapy in HCC management.

Cooperation of Sox4 with ß-catenin/p300 complex in transcriptional regulation of the Slug gene during divergent sarcomatous differentiation in uterine carcinosarcoma.

BACKGROUND: Uterine carcinosarcoma (UCS) represents a true example of cancer associated with epithelial-mesenchymal transition (EMT), which exhibits cancer stem cell (CSC)-like traits. Both Sox and ß-catenin signal transductions play key roles in the regulation of EMT/CSC properties, but little is known about their involvement in UCS tumorigenesis. Herein, we focused on the functional roles of the Sox/ß-catenin pathway in UCSs. METHODS: EMT/CSC tests and transfection experiments were carried out using three endometrial carcinoma (Em Ca) cell lines. Immunohistochemical investigation was also applied for a total of 32 UCSs. RESULTS: Em Ca cells cultured in STK2, a serum-free medium for mesenchymal stem cells, underwent changes in morphology toward an EMT appearance through downregulation of E-cadherin, along with upregulation of Slug, known as a target gene of ß-catenin. The cells also showed CSC properties with an increase in the aldehyde dehydrogenase (ALDH) 1(high) activity population and spheroid formation, as well as upregulation of Sox4, Sox7, and Sox9. Of these Sox factors, overexpression of Sox4 dramatically led to transactivation of the Slug promoter, and the effects were further enhanced by cotransfection of Sox7 or Sox9. Sox4 was also able to promote ß-catenin-mediated transcription of the Slug gene through formation of transcriptional complexes with ß-catenin and p300, independent of TCF4 status. In clinical samples, both nuclear ß-catenin and Slug scores were significantly higher in the sarcomatous elements as compared to carcinomatous components in UCSs, and were positively correlated with Sox4, Sox7, and Sox9 scores. CONCLUSIONS: These findings suggested that Sox4, as well as Sox7 and Sox9, may contribute to regulation of EMT/CSC properties to promote development of sarcomatous components in UCSs through transcriptional regulation of the Slug gene by cooperating with the ß-catenin/p300 signal pathway.

Silencing NKD2 by promoter region hypermethylation promotes gastric cancer invasion and metastasis by up-regulating SOX18 in human gastric cancer.

Naked cuticle homolog2 (NKD2) is located in chromosome 5p15.3, which is frequently loss of heterozygosity in human colorectal and gastric cancers. In order to understand the mechanism of NKD2 in gastric cancer development, 6 gastric cancer cell lines and 196 cases of human primary gastric cancer samples were involved. Methylation specific PCR (MSP), gene expression array, flow cytometry, transwell assay and xenograft mice model were employed in this study. The expression of NKD1 and NKD2 was silenced by promoter region hypermethylation. NKD1 and NKD2 were methylated in 11.7% (23/196) and 53.1% (104/196) in human primary gastric cancer samples. NKD2 methylation is associated with cell differentiation, TNM stage and distant metastasis significantly (all P < 0.05), and the overall survival time is longer in NKD2 unmethylated group compared to NKD2 methylated group (P < 0.05). Restoration of NKD2 expression suppressed cell proliferation, colony formation, cell invasion and migration, induced G2/M phase arrest, and sensitized cancer cells to docetaxel. NKD2 inhibits SOX18 and MMP-2,7,9 expression and suppresses BGC823 cell xenograft growth. In conclusion, NKD2 methylation may serve as a poor prognostic and chemo-sensitive marker in human gastric cancer. NKD2 impedes gastric cancer metastasis by inhibiting SOX18.

Sry-type HMG box 18 contributes to the differentiation of bone marrow-derived mesenchymal stem cells to endothelial cells.

OBJECTIVE: Mesenchymal stem cells (MSC) have shown therapeutic potential to engraft and either differentiate into or support differentiation of vascular endothelial cells (EC), smooth muscle cells and cardiomyocytes in animal models of ischemic heart disease. Following intracoronary or transendocardial delivery of MSCs, however, only a small fraction of cells engraft and the majority of those persist as an immature cell phenotype. The goal of the current study was to decipher the molecular pathways and mechanisms that control MSC differentiation into ECs. Vascular endothelial growth factor (VEGF-165) treatment is known to enhance in vitro differentiation of MSCs into ECs. We tested the possible involvement of the Sry-type HMG box (Sox) family of transcription factors in this process. METHOD AND RESULTS: MSCs were isolated from the bone marrow of Yucatan microswine and underwent a 10 day differentiation protocol. VEGF-165 (50ng/ml) treatment of MSCs in vitro induced a significant increase in the protein expression of VEGFR-2, Sox9 and Sox18, in addition to the EC markers PECAM-1, VE-cadherin and vWF, as determined by Western blot or flow cytometry. siRNA-mediated knockdown of Sox18, as opposed to Sox9, in MSCs prevented VEGF-165-mediated induction of EC markers and capillary tube formation. Inhibition of VEGFR-2 signaling (SC-202850) reduced Sox18 and reduced VEGF-165-induced differentiation of MSCs to ECs. CONCLUSION: Here we demonstrate that VEGF-165 mediates MSC differentiation into ECs via VEGFR-2-dependent induction of Sox18, which ultimately coordinates the transcriptional upregulation of specific markers of the EC phenotype.

MiR-492 contributes to cell proliferation and cell cycle of human breast cancer cells by suppressing SOX7 expression.

MicroRNAs (miRNAs) have emerged as important regulators that potentially play critical roles in cancer cell biological processes. Previous studies have shown that miR-492 plays an important role in cell tumorigenesis in multiple kinds of human cancer cells. However, the underlying mechanisms of this microRNA in breast cancer remain largely unknown. In the present study, we investigated miR-492's role in cell proliferation of breast cancer. MiR-492 expression was markedly upregulated in breast cancer tissues and breast cancer cells. Overexpression of miR-492 promoted the proliferation and anchorage-independent growth of breast cancer cells. Bioinformatics analysis further revealed sex-determining region Y-box 7 (SOX7), a putative tumor suppressor, as a potential target of miR-492. Data from luciferase reporter assays showed that miR-492 directly binds to the 3'-untranslated region (3'-UTR) of SOX7 messenger RNA (mRNA) and repressed expression at both transcriptional and translational levels. Ectopic expression of miR-492 led to downregulation of SOX7 protein, which resulted in the upregulation of cyclin D1 and c-Myc. In functional assays, SOX7 silenced in miR-492-in-transfected ZR-75-30 cells has positive effect to promote cell proliferation, suggesting that direct SOX7 downregulation is required for miR-492-induced cell proliferation and cell cycle of breast cancer. In sum, these results suggest that miR-492 represents a potential onco-miR and participates in breast cancer carcinogenesis by suppressing SOX7 expression.

SOX17 links gut endoderm morphogenesis and germ layer segregation.

Gastrulation leads to three germ layers--ectoderm, mesoderm and endoderm--that are separated by two basement membranes. In the mouse embryo, the emergent gut endoderm results from the widespread intercalation of cells of two distinct origins: pluripotent epiblast-derived definitive endoderm (DE) and extra-embryonic visceral endoderm (VE). Here we image the trajectory of prospective DE cells before intercalating into the VE epithelium. We show that the transcription factor SOX17, which is activated in prospective DE cells before intercalation, is necessary for gut endoderm morphogenesis and the assembly of the basement membrane that separates gut endoderm from mesoderm. Our results mechanistically link gut endoderm morphogenesis and germ layer segregation, two central and conserved features of gastrulation.

GATA6 levels modulate primitive endoderm cell fate choice and timing in the mouse blastocyst.

Cells of the inner cell mass (ICM) of the mouse blastocyst differentiate into the pluripotent epiblast or the primitive endoderm (PrE), marked by the transcription factors NANOG and GATA6, respectively. To investigate the mechanistic regulation of this process, we applied an unbiased, quantitative, single-cell-resolution image analysis pipeline to analyze embryos lacking or exhibiting reduced levels of GATA6. We find that Gata6 mutants exhibit a complete absence of PrE and demonstrate that GATA6 levels regulate the timing and speed of lineage commitment within the ICM. Furthermore, we show that GATA6 is necessary for PrE specification by FGF signaling and propose a model where interactions between NANOG, GATA6, and the FGF/ERK pathway determine ICM cell fate. This study provides a framework for quantitative analyses of mammalian embryos and establishes GATA6 as a nodal point in the gene regulatory network driving ICM lineage specification.

Notch pathway targets proangiogenic regulator Sox17 to restrict angiogenesis.

RATIONALE: The Notch pathway stabilizes sprouting angiogenesis by favoring stalk cells over tip cells at the vascular front. Because tip and stalk cells have different properties in morphology and function, their transcriptional regulation remains to be distinguished. Transcription factor Sox17 is specifically expressed in endothelial cells, but its expression and role at the vascular front remain largely unknown. OBJECTIVE: To specify the role of Sox17 and its relationship with the Notch pathway in sprouting angiogenesis. METHODS AND RESULTS: Endothelial-specific Sox17 deletion reduces sprouting angiogenesis in mouse embryonic and postnatal vascular development, whereas Sox17 overexpression increases it. Sox17 promotes endothelial migration by destabilizing endothelial junctions and rearranging cytoskeletal structure and upregulates expression of several genes preferentially expressed in tip cells. Interestingly, Sox17 expression is suppressed in stalk cells in which Notch signaling is relatively high. Notch activation by overexpressing Notch intracellular domain reduces Sox17 expression both in primary endothelial cells and in retinal angiogenesis, whereas Notch inhibition by delta-like ligand 4 (Dll4) blockade increases it. The Notch pathway regulates Sox17 expression mainly at the post-transcriptional level. Furthermore, endothelial Sox17 ablation rescues vascular network from excessive tip cell formation and hyperbranching under Notch inhibition in developmental and tumor angiogenesis. CONCLUSIONS: Our findings demonstrate that the Notch pathway restricts sprouting angiogenesis by reducing the expression of proangiogenic regulator Sox17.

Differentiation of human embryonic stem cells to hepatocyte-like cells on a new developed xeno-free extracellular matrix.

Human embryonic stem cells (hESCs) provide a new source for hepatocyte production in translational medicine and cell replacement therapy. The reported hESC-derived hepatocyte-like cells (HLCs) were commonly generated on Matrigel, a mouse cell line-derived extracellular matrix (ECM). Here, we performed the hepatic lineage differentiation of hESCs following a stepwise application of growth factors on a newly developed serum- and xeno-free, simple and cost-benefit ECM, designated "RoGel," which generated from a modified conditioned medium of human fibroblasts. In comparison with Matrigel, the differentiated HLCs on both ECMs expressed similar levels of hepatocyte-specific genes, secreted α-fetoprotein, and metabolized ammonia, showed glycogen storage activity as well as low-density lipoprotein and indocyanine green uptake. The transplantation of hESC-HLCs into the carbon tetrachloride-injured liver demonstrated incorporation of the cells into the host mouse liver and the expression of albumin. The results suggest that the xeno-free and cost-benefit matrix may be applicable in bioartificial livers and also may facilitating a clinical application of human pluripotent stem cell-derived hepatocytes in the future.