Disruption of the transcription factor recombination signal-binding protein-Jkappa (RBP-J) leads to veno-occlusive disease and interfered liver regeneration in mice.

UNLABELLED: Liver sinusoid (LS) endothelial cells (LSECs) support hepatocytes in resting livers and proliferate during liver regeneration to revascularize regenerated liver parenchyma. We report that recombination signal-binding protein-Jkappa (RBP-J), the critical transcription factor mediating Notch signaling, regulates both resting and regenerating LSECs. Conditional deletion of RBP-J resulted in LSEC proliferation and a veno-occlusive disease-like phenotype in the liver, as manifested by liver congestion, deposition of fibrin-like materials in LSs, edema in the space of Disse, and increased apoptosis of hepatocytes. Regeneration of liver was remarkably impaired, with reduced LSEC proliferation and destroyed sinusoidal structure. LSEC degeneration was obvious in the regenerating liver of RBP-J-deficient mice, with some LSECs losing cytoplasm, and organelles protruding into the remnant plasma-membrane of LSs to hamper the microcirculation and intensify veno-occlusive disease during liver regeneration. Hepatocytes were also degenerative, as shown by dilated endoplasmic reticulum, decreased proliferation, and increased apoptosis during liver regeneration. Molecular analyses revealed that the dynamic expression of several related molecules-such as vascular endothelial growth factor, vascular endothelial growth factor receptors 1 and 2, interleukin-6, and hepatocyte growth factor-was disturbed. CONCLUSION: Notch/RBP-J signaling may play dual roles in LSECs: in resting liver it represses proliferation, and in regenerating liver it supports proliferation and functional differentiation.

Notch signaling inhibits the growth of the human chronic myeloid leukemia cell line K562.

Notch signaling functions in the development of some types of leukemia and lymphoma, but the relationship between Notch signaling and chronic myeloid leukemia (CML) remains to be elucidated. In this study, we examined the expression of Notch receptors and ligands in the human CML cell line K562. When the active form of Notch1, the Notch intra-cellular domain (NIC), was over-expressed in K562, the proliferation of K562 was mildly but significantly inhibited, accompanied by increased Hes1 mRNA level. On the other hand, when Notch signaling was attenuated by over-expression of a dominant-negative RBP-J, RBP-J(R218H), in K562 cells, the proliferation of K562 was increased. Moreover, we found that activation of Notch signaling inhibited while repression of Notch signaling promoted the colony-forming activity of K562 cells. We examined cell cycle-related molecules in K562 transfected with NIC or RBP-J(R218H), and found that the protein level of the retinoblastoma gene product (the Rb protein) was induced in K562 expressing NIC, and down-regulated in K562 expressing RBP-J(R218H). These data suggest that the Notch signaling may function as a tumor inhibitor in human CML cells.

RBP-J, the transcription factor downstream of Notch receptors, is essential for the maintenance of vascular homeostasis in adult mice.

In adults, angiogenic abnormalities are involved in not only tumor growth but several human inherited diseases as well. It is unclear, however, concerning how the normal vascular structure is maintained and how angiogenesis is initiated in normal adults. Using the Cre-LoxP-mediated conditional gene deletion, we show in the present study that in adult mice disruption of the transcription factor recombination signal-binding protein Jkappa (RBP-J) in endothelial cells strikingly induced spontaneous angiogenesis in multiple tissues, including retina and cornea, as well as in internal organs, such as liver and lung. In a choroidal neovascularization model, which mimics the angiogenic process in tumor growth and age-related macular degeneration, RBP-J deficiency induced a more intensive angiogenic response to injury. This could be transmitted by bone marrow, indicating that RBP-J could modulate bone marrow-derived endothelial progenitor cells in adult angiogenesis. In addition, in the absence of RBP-J, proliferation of endothelial cells increased significantly, leading to accumulative vessel outgrowth. These findings suggest that in adults RBP-J-mediated Notch signaling may play an essential role in the maintenance of vascular homeostasis by repressing endothelial cell proliferation.

Notch signaling regulates the FOXP3 promoter through RBP-J- and Hes1-dependent mechanisms.

Evidence has shown that Notch signaling modulates CD4(+)CD25(+) regulatory T-cells (Tregs). As transcription factor Foxp3 acts as a master molecule governing the development and function of Tregs, we investigated whether Notch signaling might directly regulate Foxp3 expression. Here, we provide evidence that Notch signaling can modulate the FOXP3 promoter through RBP-J- and Hes1-dependent mechanisms. A conserved RBP-J-binding site and N-box sites were identified within the FOXP3 promoter. We show that the Notch intracellular domain (NIC), the active form of Notch receptors, activates a reporter driven by the FOXP3 promoter. Dissection of the FOXP3 promoter revealed bipartite effects of the RBP-J-binding site and the N-boxes: the RBP-J-binding site positively, while the N-boxes negatively regulated the FOXP3 promoter activity. Moreover, in freshly isolated Tregs, NIC-RBP-J complex is bound to the FOXP3 promoter in Tregs. Our results suggest that Notch signaling might be involved in the development and function of Tregs through regulating Foxp3 expression.

[Correlation analysis of thrombin-activatable fibrinolysis inhibitor single nucleotide polymorphism with venous thromboembolism].

This study was aimed to explore the change of single nucleotide polymorphism (SNP) of thrombin-activatable fibrinolysis inhibitor (TAFI) and its correlation of 2 sites (505a/g, 1040c/t) in its gene-coding region with venous thromboembolism (VTE). The genotype distribution of TAFI in 80 patients with VTE and 80 normal controls was detected by allele-specific PCR. The results showed that the distribution of each genotype of 505a/g polymorphism was not significantly different between the VTE and control groups (P > 0.05). However, t allele frequency of 1040c/t in VTE group decreased significantly as compared with the control group (40% vs 53.75%, P < 0.05), mainly due to the decrease of the proportion of tt homozygous in VTE group. It is concluded that obvious relationship is found between the polymorphism of 1040c/t in TAFI gene and VTE patients. t allele genotype may paly a protective role in VTE. The polymorphism of TAFI 505a/g may be not associated with VTE.

[1059 g/c gene polymorphism of C-reactive protein in patients with deep vein thrombosis].

This study was aimed to investigate the distribution of 1059 G/C gene polymorphism of C-reactive protein(CRP) in deep vein thrombus (DVT) and its clinical significance. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to screen 1059 G/C polymorphism in exon 2 of C-reactive protein gene in 61 cases of DVT and 60 healthy controls. The frequency of mutation was calculated. The results showed that there was no statistical difference of 1059 G/C genotype and mutation frequency of allele between deep vein thrombosis group and control group (p > 0.05). It is concluded that the 1059 G/C gene polymorphism of CRP displays certain difference in races and areas, and whether 1059 G/C gene polymorphism of CRP is a dangerous factor for deep vein thrombosis, which needs to be deeply explored.

[Correlation of inflammatory marker and coagulation factors with deep vein thrombosis].

This study was purposed to investigate the correlation of deep vein thrombosis (DVT) with C-reactive protein (CRP), fibrinogen (Fg), coagulation factor VIII (FVIII:C), coagulation factor IX (FIX:C) and to explore the effect of inflammation and coagulation as well as their interaction in DVT and its mechanism. 59 patients with DVT undergoing selective venous ultrasonography and 26 healthy individuals as controls were enrolled in this study. The plasma level of CRP was detected by immunoturbidimetry, FVIII:C, FIX:C levels were determined by a one-stage assay and fibrinogen level was measured by full-automatic biochemical apparatus. The results showed that the mean levels of plasma CRP, Fg, FVIII:C and FIX:C were significantly higher in deep vein thrombosis group than that in controls [CRP (2.67 +/- 0.91) vs (0.14 +/- 0.08) mg/dl; Fg (4.73 +/- 1.36) vs (2.79 +/- 0.66)g/L; FVIII:C (126.71 +/- 28.10) vs (81.35 +/- 20.77)%; FIX:C (81.01 +/- 23.60) vs (70.71 +/- 11.3)%] (p < 0.01), and the level of plasma CRP was strongly correlated with Fg, FVIII:C and FIX:C (r(s) = 0.432, 0.571 and 0.544, p < 0.01). It is concluded that the DVT and inflammation are closely related, increased level of plasma CRP may be a predictor of DVT. Increased plasma levels of Fg, FVIII:C and FIX:C all are important risk factors to DVT. Interaction between inflammation and coagulation promote the incidence of DVT, which may be one of DVT pathogenesis.

[Gene mutation analysis of one case with von willebrand disease type 2A].

Objective of this study was to identify gene mutation involved in a patient with type 2A von Willebrand disease (vWD). The bleeding time, vWF:Ag, FVIII:C, RIPA and multimeric assay were used for phenotypic diagnosis. All of the 52 exons and the exon-intron boundaries of vWF gene were amplified by polymerase chain reaction (PCR) and direct sequencing was carried out. The results indicated that the levels of vWF:Ag, FVIII:C and RIPA decreased in this patient, the vWF multimer with high and intermediate molecular weight was absent in plasma. The sequencing of genomic DNA revealed a C4738G (L1580V) missense mutation in the vWF gene from the patient. In conclusion, the C4738G (L1580V) missense mutation effecting the form of vWF multimer was responsible to molecular mechanism in this patient with vWD.

[Detection of factor IX gene mutation in patients with hemophilia B by DNA sequencing].

In order to investigate the patterns of FIX gene mutation in 3 unrelated hemophilia B (HB) patients, the activated partial thromboplastin time (APTT) and FIX activity (FIX: C) tests were adopted for phenotype diagnosis. All of the eight exons and their flank of FIX gene were amplified by polymerase chain reaction (PCR), the nucleic acid sequences were detected by dideoxymediated chain-termination method. The results indicated that as compared with normal control, the APTT value significantly increased, FIX: C value obviously decreased, PT value was normal. Sequencing results showed that all of 3 HB patients had the changes of gene sequences, among 3 patients the G22119A point mutation of exon 6 existed in case No.1, the G7932C point mutation of exon 2 was detected in case No.2 and the T32685C point mutation of exon 8 was found in case No.3. In conclusion, the relevant changes of gene sequences in all of 3 HB patients were detected, which provides some evidences for molecular mechanism of gene deficiency in HB patients.

Notch activation promotes cell proliferation and the formation of neural stem cell-like colonies in human glioma cells.

Since Notch signaling plays a critical role in stem cells and oncogenesis, we hypothesized that Notch signaling might play roles in cancer stem cells and cancer cells with a stem cell phenotype. In this study, we accessed potential functions of the Notch pathway in the formation of cancer stem cells using human glioma. Using RT-PCR, we found that most human astrogliomas of different grades expressed moderate to high level of Notch receptors and ligands. mRNA of Hes5 but not Hes1, both of which are major downstream molecules of the Notch pathway, was also detected. In human glioma cell lines BT325, U251, SHG-44, and U87, mRNA encoding different types of Notch receptors were detected, but active form of Notch1 (NIC) was only detected in SHG-44 and U87 by Western blot. Interestingly, proliferation of these two glioma cell lines appeared faster than that of the other two lines in which NIC was not detected. We have over-expressed NIC of Notch1 in SHG-44 cells by constitutive transfection to evaluate the effects of Notch signaling on glioma cells. Our results showed that over-expression of NIC in SHG-44 cells promoted the growth and the colony-forming activity of SHG-44 cells. Interestingly, over-expression of NIC increased the formation neurosphere-like colonies in the presence of growth factors. These colonies expressed nestin, and could be induced to cells expressing neuron-, astrocyte-, or oligodendrocyte-specific markers, consistent with phenotypes of neural stem cells. These data suggest that Notch signaling promote the formation of cancer stem cell-like cells in human glioma.

[Analysis of activated protein C resistance, factor V coagulation activity and gene polymorphisms in patients with venous thromboembolism].

The study was aimed to investigate the factor V coagulation activity (FV:C), and to evaluate FVgene polymorphisms and activated protein C resistance (APCR) in the patients with venous thromboembolism (VTE). 95 patients with VTE and 95 normal controls were investigated for FV gene polymorphisms. FV Leiden, FVCambridge, and FVHong Kong were detected by PCR, MnlI and BstNI digestion respectively. FVAsp79His and FVI359T were detected by MassARRAY. FV:C and APCR in 65 patients with VTE and 60 normal controls were determined by a one-stage clotting method and the APTT-based assays respectively. The results showed that the mean levels of plasma FV:C were significantly higher in VTE group than that in controls (108.03% +/- 28.29% vs 95.17% +/- 29.75%) (P = 0.008), the incidence of APCR were 20.0% (13 of 65 cases) in patients with VTE and 5.0% (3 of 60 cases) in normal controls (P = 0.012). FV Leiden, FVCambridge, FVHong Kong, FVAsp79His and FVI359T mutations were not found in two groups. It is concluded that the increased plasma level of FV:C is a risk factor for VTE. There is APCR in both groups, APCR is also a risk factor to VTE. APCR may not be associated with mutations of FV Leiden, FVCambridge, FVHong Kong, FVAsp79His and FV I359T polymorphisms, other factors need to study further in APCR.

[A novel mutation causes congenital factor V deficiency].

OBJECTIVE: To investigate the gene defect in a hereditary coagulation factor V (FV) deficiency family. METHODS: The plasma FV actigen was measured by one-stage clotting assay. The FV antigen was assayed by Biotin-Avidin enzyme linked immunosorbent assay (BA-ELISA). The full length of exon 1 to exon 25 and the 5' untranslated sequence of FV genomic DNA were analyzed by polymerase chain reaction (PCR) and direct sequencing of the amplified fragments, meanwhile the defect was identified by T/A cloning sequencing. RESULTS: The plasma coagulant activity and amount of FV of the proband were marked deficient (1% and 1.54%, respectively). DNA sequence analysis for the proband revealed a causative mutation in a heterozygous status. It was one base pair deletion in exon 4 at nucleotide 675 inherited from her mother. CONCLUSIONS: A novel mutation in the FV gene was identified in the proband with congenital FV deficiency. The mutation was 675delA in exon 4 resulting in a frameshift and a premature termination codon.