gp130-mediated signaling is involved in both chondrogenesis and osteogenesis, but its direct role in the formation of embryonic Meckel's cartilage and associated mandibular development has not yet been elucidated. In this study, we examined the influence of gp130 ablation on the developing mandibular Meckel's cartilage by evaluating the morphological and histological changes as well as the gene expression patterns in developing embryonic gp130-/- mice. The ablation of the gp130 gene showed no change in region-specific collagen mRNA expression except for a slight delay in its expression but caused shortened embryonic Meckel's cartilage, delayed hypertrophic chondrocyte maturation and subsequent bony replacement with characteristic bending of the intramandibular Meckel's cartilage. The bending of Meckel's cartilage led to a narrow mandibular arch at the rostral area with poor cortical plate formation. These findings indicate that gp130-mediated signaling is important for the normal morphogenesis of Meckel's cartilage and subsequent mandibular development.
Animals ; Body Patterning ; Cartilage/embryology/metabolism/*physiology ; Collagen ; Cytokine Receptor gp130/genetics/*physiology ; Mandible/embryology/metabolism/*physiology ; Mice ; Mice, Knockout

Mouse embryonic stem cells (ES cells) are pluripotent in that they can give rise to almost all the cell types in vitro and in vivo. Also, they can sustain self-renewal in vitro owing to symmetrical mitosis, i.e., only the cell number increases while the daughter cells remain pluripotent. Self-renewal and pluripotency of ES cells are under stringent regulation of several signaling pathways. Activation of either JAK-STAT3 or PI3K, the downstream cascade of gp130, can maintain the self-renewal of ES cells, while phosphorylation of another gp130-related branch, SHP2-Ras-ERK, drives the differentiation. BMP2/4-mediated signaling is capable of suppressing the differentiation of ES cells in collaboration with activated JAK-STAT3 under serum free culture conditions. Other signaling such as Wnt also contributes to the self-renewal of ES cells. Generally, the network, which is composed of various signaling pathways, modulates the self-renewal and differentiation of mouse ES cells precisely. This review focuses on the role of gp130 in proliferation of mouse ES cells including inhibitory effect of JAK-STAT3 pathway activation on differentiation of mouse ES cells, maintenance effect of PI3K pathway activation on self-renewal of ES cells, promotive effect of SHP-2-Ras-ERK pathway activation on differentiation of ES cells, and influence of other signaling pathways on self-renewal of mouse ES cells, including maintenance effect of BMP combination with LIF under serum free culture conditions on self-renewal of ES cells and promotive effect of Wnt pathway activation on self-renewal of ES cells.
Animals ; Cell Differentiation ; physiology ; Cell Proliferation ; Cell Survival ; Cells, Cultured ; Cytokine Receptor gp130 ; metabolism ; Embryonic Stem Cells ; cytology ; physiology ; Janus Kinase 1 ; metabolism ; Leukemia Inhibitory Factor ; metabolism ; Mice ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; physiology

The goal of this study was to investigate the regulatory effect of angiotensin converting enzyme 2 (ACE2) on cellular inflammation caused by avian infectious bronchitis virus (IBV) and the underlying mechanism of such effect. Vero and DF-1 cells were used as test target to be exposed to recombinant IBV virus (IBV-3ab-Luc). Four different groups were tested: the control group, the infection group[IBV-3ab-Luc, MOI (multiplicity of infection)=1], the ACE2 overexpression group[IBV-3ab Luc+pcDNA3.1(+)-ACE2], and the ACE2-depleted group (IBV-3ab-Luc+siRNA-ACE2). After the cells in the infection group started to show cytopathic indicators, the overall protein and RNA in cell of each group were extracted. real-time quantitative polymerase chain reaction (RT-qPCR) was used to determine the mRNA expression level of the IBV nucleoprotein (IBV-N), glycoprotein 130 (gp130) and cellular interleukin-6 (IL-6). Enzyme linked immunosorbent assay (ELISA) was used to determine the level of IL-6 in cell supernatant. Western blotting was performed to determine the level of ACE2 phosphorylation of janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3). We found that ACE2 was successfully overexpressed and depleted in both Vero and DF-1 cells. Secondly, cytopathic indicators were observed in infected Vero cells including rounding, detaching, clumping, and formation of syncytia. These indicators were alleviated in ACE2 overexpression group but exacerbated when ACE2 was depleted. Thirdly, in the infection group, capering with the control group, the expression level of IBV-N, gp130, IL-6 mRNA and increased significantly (P < 0.05), the IL-6 level was significant or extremely significant elevated in cell supernatant (P < 0.05 or P < 0.01); the expression of ACE2 decreased significantly (P < 0.05); protein phosphorylation level of JAK2 and STAT3 increased significantly (P < 0.05). Fourthly, comparing with the infected group, the level of IBV-N mRNA expression in the ACE2 overexpression group had no notable change (P > 0.05), but the expression of gp130 mRNA, IL-6 level and expression of mRNA were elevated (P < 0.05) and the protein phosphorylation level of JAK2 and STAT3 decreased significantly (P < 0.05). In the ACE2-depleted group, there was no notable change in IBV-N (P > 0.05), but the IL-6 level and expression of mRNA increased significantly (P < 0.05) and the phosphorylation level of JAK2 and STAT3 protein decreased slightly (P > 0.05). The results demonstrated for the first time that ACE2 did not affect the replication of IBV in DF-1 cell, but it did contribute to the prevention of the activation of the IL-6/JAK2/STAT3 signaling pathway, resulting in an alleviation of IBV-induced cellular inflammation in Vero and DF-1 cells.
Animals ; Chlorocebus aethiops ; Humans ; Interleukin-6/genetics* ; Janus Kinase 2/pharmacology* ; Infectious bronchitis virus/metabolism* ; STAT3 Transcription Factor/metabolism* ; Angiotensin-Converting Enzyme 2/pharmacology* ; Cytokine Receptor gp130/metabolism* ; Vero Cells ; Signal Transduction ; Inflammation ; RNA, Messenger

BACKGROUNDThe Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway and the extracellular signal-regulated kinases 1/2 (ERK1/2) pathway are the two major independent signal transduction pathways. However, it has recently been found that STAT3 may be negatively regulated by ERK1/2 in gp130-dependent signaling. Cardiotrophin-1 (CT-1), a potent novel hypertrophic cytokine, depends on gp130 to induce signaling and depends on STAT3 to exert hypertrophic effect. In this study, we examined whether STAT3 activity was negatively regulated by ERK1/2 during CT-1-induced signaling in rat cardiomyocytes and, if so, whether such crosstalk interfered with the hypertrophic effect of CT-1 and, furthermore, whether the mechanism underlying the crosstalk involved phosphorylation of serine 727 (S727) in STAT3.

METHODSThe activities of ERK1/2 and STAT3 were assessed by in-gel kinase assay and Western blot analysis, respectively. The role of S727 phosphorylation in the crosstalk between ERK1/2 and STAT3 was determined by a transient transfection study using a STAT3S727A mutant. Cardiomyocyte hypertrophy was evaluated by the cellular protein-to-DNA ratio and [(3)H]-leucine incorporation.

RESULTSCT-1 simultaneously activated both ERK1/2 and STAT3 in rat cardiomyocytes. Inhibition of ERK1/2 by U0126 resulted in an increase of CT-1-induced tyrosine phosphorylation of STAT3 and, consequently, the protein-to-DNA ratio and [(3)H]-leucine incorporation. Transient transfection of the cells with STAT3S727A had no significant effect on CT-1-induced tyrosine phosphorylation of STAT3.

CONCLUSIONSSTAT3 is activated by CT-1 in rat cardiomyocytes, but full activation is mitigated by the simultaneous activation of ERK1/2. The inhibition of ERK1/2 increases the activity of STAT3, which, in turn, enhances the hypertrophic effect of CT-1. The crosstalk between ERK1/2 and STAT3 is independent of the phosphorylation of the S727 in STAT3. Such crosstalk may contribute to the development of adequate cardiac hypertrophy.

Active Transport, Cell Nucleus ; Animals ; Antigens, CD ; metabolism ; Cardiomegaly ; chemically induced ; metabolism ; Cytokine Receptor gp130 ; Cytokines ; toxicity ; DNA-Binding Proteins ; physiology ; Membrane Glycoproteins ; metabolism ; Mitogen-Activated Protein Kinase 1 ; physiology ; Mitogen-Activated Protein Kinase 3 ; physiology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; STAT3 Transcription Factor ; Trans-Activators ; physiology ; Tyrosine ; metabolism

OBJECTIVETo observe the effect of Chinese herbs for supplementing Shen and strengthening bone (HB) on myelogenic osteoclasts formation, and gene expression of interleukin-6 (IL-6), IL-6 receptor (IL-6R) and gp130 in bone marrow.

METHODSSeventy-two healthy female SD rats of 3 months, were randomly divided into three groups, 24 in the sham-operated group (A), 24 in the ovariectomized group (B) and 24 in the after ovariectomy HB treated group (C). Bone marrow cells of 6 rats from each group were respectively collected and cultured at four time points (2nd, 4th, 6th and 12th weeks after operation). After 6 days of culture, the bone marrow cells were differentiated by Wright-Giemsa stain and TRAP stain, and total RNA in them was extracted by TRIZOL.

RESULTSBeginning from the 2nd week, the osteoclasts formation in Group B was higher than that in Group A (P < 0.05), and IL-6, IL-6R gene expression significantly increased in Group B (P < 0.05 or P < 0.01). These changes reached the peak in the 4th to 6th week, with the level maintained to the 12th week. As for comparison of Group B and C, the above-mentioned changes were significantly weakened in the latter (P < 0.05 or P < 0.01). No significant change of gp130 gene expression revealed in the whole course in either group.

CONCLUSIONHB could inhibit the myelogenic osteoclasts formation in ovariectomized rats, this effect may be correlated with, partially at least, its inhibitory effect on the over-expressed IL-6 and IL-6R gene expression in myelocytes after ovariectomy.

Animals ; Antigens, CD ; biosynthesis ; genetics ; Bone Marrow ; metabolism ; Cell Division ; drug effects ; Cells, Cultured ; Cytokine Receptor gp130 ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; Female ; Granulocyte Precursor Cells ; metabolism ; Interleukin-6 ; biosynthesis ; genetics ; Isoflavones ; pharmacology ; Membrane Glycoproteins ; biosynthesis ; genetics ; Osteoblasts ; pathology ; Osteoporosis ; metabolism ; pathology ; Ovariectomy ; RNA ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Interleukin-6 ; biosynthesis ; genetics

OBJECTIVETo investigate the biological activity and molecular mechanism of interferon alpha (IFNalpha) on human myeloma cell line Sko-007.

METHODSThe effect of IFNalpha on the growth of Sko-007 cells was measured by MTT assay. Cells cycle distribution and the expression of two IL-6 receptor chains (IL-6R and gp130) on Sko-007 cell surface in the absence or presence of IFNalpha were monitored by FACS analysis. The activation state of protein kinase ERK, which is involved in Ras/MAPK signal transduction pathway mediating cell survival and proliferation, and the expression of anti-apoptotic Bcl-2 family proteins-Bcl-2, Bcl-x(L) and Mcl-1 in Sko-007 cells with or without IFNalpha were determined by immunoblot assay.

RESULTIFNalpha arrested Sko-007 cell cycle progression. After stimulation with IFNalpha, an obvious increase in G(0)/G(1) phase (41.1%-->84.1%) and decrease in S phase (57.1%-->13.3%) of Sko-007 cell cycle distribution can be observed. Moreover, the proliferation of Sko-007 cells was dramatically inhibited in the presence of IFNalpha, with a maximal inhibitory rate up to 88%. In addition, the expression of gp130 on cell surface, the activation of protein kinase ERK and the expression of Bcl-2 and Bcl-x(L) were all down-regualted in IFNalpha-stimulated Sko-007 cells.

CONCLUSIONThe inhibitory effect of IFNalpha on the proliferation of Sko-007 cells was mediated by gp130 down-regulation, degradation of Bcl-2 family anti-apoptotic proteins and inhibition of ERK activation.

Antigens, CD ; drug effects ; metabolism ; Cell Cycle ; drug effects ; Cell Division ; drug effects ; Cytokine Receptor gp130 ; Dose-Response Relationship, Drug ; Down-Regulation ; Enzyme Activation ; drug effects ; G1 Phase ; drug effects ; Humans ; Immunoblotting ; Interferon-alpha ; pharmacology ; Membrane Glycoproteins ; drug effects ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Multiple Myeloma ; metabolism ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Receptors, Interleukin-6 ; drug effects ; metabolism ; Resting Phase, Cell Cycle ; drug effects ; S Phase ; drug effects ; Tumor Cells, Cultured ; drug effects ; metabolism ; bcl-X Protein