Embryonic stem cells (ESCs) is one of the best cell types for regenerative medicine. It is derived from inner cell mass of the blastocyst stage and characterized by self-renewal and pluripotency, which are regulated by kinds of signal molecules, such as the Wnt/β-catenin signaling pathway. β-catenin is a multifunctional protein and plays a key role in Wnt/β-catenin signaling pathway. β-catenin involves self-renewal of ESCs and promotes the differentiation of ESCs into three primary germ layers in space and time. Elucidating the mechanisms of β-catenin in regulating the self-renewal and pluripotency of ESCs will pave the way to use it in research and application.
Blastocyst ; cytology ; Cell Differentiation ; Embryonic Stem Cells ; cytology ; Humans ; Wnt Signaling Pathway ; beta Catenin ; physiology

More and more scholars agreed with the viewpoint that osteonecrosis relates with the metabolic activity of chondrocyte. Moreover,the activation of beta-catenin among Wnt/beta-catenin signal pathway can promote differentiation of chondrocyte and can promote differentiated cell death. So it suggests that this signal pathway should have an effect to occurrence and development of osteonecrosis by regulating the metabolic activity of chondrocyte. Through the establishment of conditional beta-catenin knockout mice,it is helpful to understand the pathogenesis of Wnt/beta-catenin signal pathway regulating cartilage metabolism. By the way we can understand the pathogenesis of osteonecrosis and give a targeted treatment to the disease. This article reviewed the relationship of three aspects of Wnt/beta-catenin signal pathway, cartilage metabolism and osteonecrosis.
Animals ; Cartilage ; metabolism ; Humans ; Mice ; Osteonecrosis ; metabolism ; Signal Transduction ; physiology ; Wnt Signaling Pathway ; physiology ; beta Catenin ; physiology

BACKGROUNDCognitive impairment is a severe complication caused by obstructive sleep apnea (OSA). The mechanisms of causation are still unclear. The Wnt/β-catenin signaling pathway is involved in cognition, and abnormalities in it are implicated in neurological disorders. Here, we explored the Wnt/β-catenin signaling pathway abnormalities caused by chronic intermittent hypoxia (CIH), the most characteristic pathophysiological component of OSA.

METHODSWe divided 32 4-week-old male C57/BL mice into four groups of eight each: a CIH + normal saline (NS) group, CIH + LiCl group, sham CIH + NS group, and a sham CIH + LiCl group. The spatial learning performance of each group was assessed by using the Morris water maze (MWM). Protein expressions of glycogen synthase kinase-3β (GSK-3β) and β-catenin in the hippocampus were examined using the Western blotting test. EdU labeling and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining methods were used, respectively, to determine the proliferation and apoptosis of neurons in the hippocampal dentate gyrus region.

RESULTSMice exposed to CIH showed impaired spatial learning performance in the MWM, including increased mean escape latencies to reach the target platform, decreased mean times passing through the target platform and mean duration in the target quadrant. The GSK-3β activity increased, and expression of β-catenin decreased significantly in the hippocampus of the CIH-exposed mice. Besides, CIH significantly increased hippocampal neuronal apoptosis, with an elevated apoptosis index. Meanwhile, LiCl decreased the activity of GSK-3β and increased the expression of β-catenin and partially reversed the spatial memory deficits in MWM and the apoptosis caused by CIH.

CONCLUSIONSWnt/β-catenin signaling pathway abnormalities possibly play an important role in the development of cognitive deficits among mice exposed to CIH and that LiCl might attenuate CIH-induced cognitive impairment via Wnt/β-catenin signaling pathway.

Animals ; Chronic Disease ; Cognitive Dysfunction ; etiology ; physiopathology ; Glycogen Synthase Kinase 3 beta ; physiology ; Hypoxia ; complications ; physiopathology ; Male ; Mice ; Mice, Inbred C57BL ; Wnt Signaling Pathway ; physiology ; beta Catenin ; physiology

More than 80% of all cases of deafness are related to the death or degeneration of cochlear hair cells and the associated spiral ganglion neurons, and a lack of regeneration of these cells leads to permanent hearing loss. Therefore, the regeneration of lost hair cells is an important goal for the treatment of deafness. Atoh1 is a basic helix-loop-helix (bHLH) transcription factor that is critical in both the development and regeneration of cochlear hair cells. Atoh1 is transcriptionally regulated by several signaling pathways, including Notch and Wnt signalings. At the post-translational level, it is regulated through the ubiquitin-proteasome pathway. In vitro and in vivo studies have revealed that manipulation of these signaling pathways not only controls development, but also leads to the regeneration of cochlear hair cells after damage. Recent progress toward understanding the signaling networks involved in hair cell development and regeneration has led to the development of new strategies to replace lost hair cells. This review focuses on our current understanding of the signaling pathways that regulate Atoh1 in the cochlea.
Basic Helix-Loop-Helix Transcription Factors/physiology* ; Cell Differentiation ; Cochlea/physiology* ; Hair Cells, Auditory/physiology* ; Hearing Loss/etiology* ; Humans ; Proteasome Endopeptidase Complex/physiology* ; Signal Transduction/physiology* ; Transcription Factors/physiology* ; Ubiquitin/metabolism* ; Wnt Signaling Pathway ; beta Catenin/physiology*

Both bone morphogenetic protein 2 (BMP2) and the wingless-type MMTV integration site (WNT)/β-catenin signalling pathway play important roles in odontoblast differentiation and dentinogenesis. Cross-talk between BMP2 and WNT/β-catenin in osteoblast differentiation and bone formation has been identified. However, the roles and mechanisms of the canonical WNT pathway in the regulation of BMP2 in dental pulp injury and repair remain largely unknown. Here, we demonstrate that BMP2 promotes the differentiation of human dental pulp cells (HDPCs) by activating WNT/β-catenin signalling, which is further mediated by p38 mitogen-activated protein kinase (MAPK) in vitro. BMP2 stimulation upregulated the expression of β-catenin in HDPCs, which was abolished by SB203580 but not by Noggin or LDN193189. Furthermore, BMP2 enhanced cell differentiation, which was not fully inhibited by Noggin or LDN193189. Instead, SB203580 partially blocked BMP2-induced β-catenin expression and cell differentiation. Taken together, these data suggest a possible mechanism by which the elevation of β-catenin resulting from BMP2 stimulation is mediated by the p38 MAPK pathway, which sheds light on the molecular mechanisms of BMP2-mediated pulp reparative dentin formation.
Bone Morphogenetic Protein 2 ; physiology ; Cell Differentiation ; physiology ; Dental Pulp ; cytology ; Humans ; MAP Kinase Signaling System ; Wnt Proteins ; metabolism ; beta Catenin ; metabolism

OBJECTIVE: To investigate the regulation mechanism of RhoA signaling pathway during the enamel formation by using the EGFP-RhoA^{Dominant Negative} (EGFP-RhoA^DN) transgenic mice model, from the aspect of adherens junctions, and to provide a theory basis for mechanism of enamel development defects. METHODS: The enamel thickness of mandibular first molars of EGFP-RhoA^DN transgenic mice and wild type (WT) mice were observed by scanning electronic microscopy at 20 kV, and the enamel thickness of the distal face of the central cusp was measured at 10 locations via analysis by ImageJ (Rasband, 1997-2009). The enamel organs from mandibular first molars from postnatal-4-day (P4) EGFP-RhoA^DN mice and wild type mice were isolated, and the total RNA and protein were extracted from the epithelium of the enamel organs. The expression level of the adherens junctions components in ameloblasts layer of the postnatal-4-day EGFP-RhoA^DN transgenic mice and wild type mice mandibular first molars were detected by real-time PCR and Western blot assay. RESULTS: The EGFP-RhoA^DN transgenic mice had decreased enamel thickness in their bilateral mandibular first molars versus those of control group (n=20), and enamel thickness was (84.60±0.20) μm vs. (106.24±0.24) μm, P<0.05. The protein expressions of E-cadherin, α-E-catenin and pan-cadherin in ameloblasts layer of postnatal-4-day EGFP-RhoA^DN transgenic mice molars were down-regulated, and the protein level of β-catenin in ameloblasts layer of P4 EGFP-RhoA^DN transgenic mice molars was up-regulated. The mRNA level of E-cadherin in ameloblasts layer of P4 EGFP-RhoA^DN transgenic mice molars was down-regulated versus that of WT mice, and the gene expression of E-cadherin was 0.93±0.01 vs. 1.00±0.02, P<0.05. The mRNA level of β-catenin in ameloblasts layer of P4 EGFP-RhoA^DN transgenic mice molars was up-regulated versus that of WT mice, and the gene expression of β-catenin was 1.23±0.03 vs. 1.00±0.05, P<0.05. CONCLUSION In the mandibular first molars of EGFP-RhoA^DN transgenic mice, the enamel formation was disrupted and the adherens junctions of EGFP-RhoA^DN transgenic mice ameloblasts were implicated during amelogenesis. RhoA signaling pathway may play a critical role in enamel development by altering the adherens junctions in ameloblasts.
Adherens Junctions ; Ameloblasts ; Amelogenesis ; Animals ; Antigens, CD ; Cadherins/metabolism* ; Dental Enamel/metabolism* ; Enamel Organ ; Humans ; Mice ; Mice, Transgenic ; Molar ; Signal Transduction ; alpha Catenin ; beta Catenin ; rhoA GTP-Binding Protein/physiology*

OBJECTIVETo investigate the role that E-cadherin (E-cad) plays on cell adhesion and proliferation of human breast carcinoma.

METHODSE-cad expression vector was transfected into an E-cad-negative human breast carcinoma MDA-MB-231 cells. G418 was used to screen positive clones. E-cad, &beta;-catenin (&beta;-cat) and cyclin D1 expressions of these clones were confirmed by Western blot. Their cell-cell and cell-matrix adhesion abilities were detected. E-cad/&beta;-catenin interaction was confirmed by immunoprecipitation. Cell proliferation was evaluated by MTT. Cell apoptosis was analyzed by flow cytometry. Direct two-step immunocytochemistry was used to detect the localization of &beta;-cat.

RESULTE-cad(+) cell strains Ecad-231-7 and Ecad-231-9 were established. When cultured in ultra-low-binding dishes Ecad-231 cells grow in suspension while Ecad-231-7 and Ecad-231-9 cells grow in large clamps. When co-cultured with HCT116 cells, the average adhesion rates at 30 min are 39.0%, 60.0% and 59.5% for MDA-MB-231, Ecad-231-7 and Ecad-231-9 respectively. The average detachment rates by EDTA for 5 min are 37.4%, 4.2% and 7.4% respectively. So E-cad expression enhanced hemotypic and heterotypic cell-cell adhesion and cell-matrix adhesion. Forced exogenously expressed E-cad could combine with endogenous &beta;-cat, whereas down stream cyclin D1 expression was significantly decreased, as evidenced by Western blot. The rates of cell apoptosis of MDA-MB-231, Ecad-231-7 and Ecad-231-9 were 1.8%, 2.0% and 2.1%. Expression of E-cad had no obvious effect on the apoptosis of tumor cells with regular culture. &beta;-cat increased in the cytoplasma.

CONCLUSIONSTwo monoclonal tumor cell strains (Ecad-231-7 and Ecad-231-9) stably expressing E-cad were successfully established. E-cad could enhance adhesion and inhibit proliferation of human breast carcinoma cells through a pathway involving &beta;-cat and cyclin D1.

Apoptosis ; Breast Neoplasms ; metabolism ; pathology ; Cadherins ; genetics ; metabolism ; physiology ; Cell Adhesion ; Cell Line, Tumor ; Cell Proliferation ; Cyclin D1 ; metabolism ; Female ; Genetic Vectors ; Humans ; Plasmids ; Transfection ; beta Catenin ; metabolism

Animals ; Apoptosis ; Cell Membrane ; metabolism ; Cell Nucleus ; metabolism ; Colonic Neoplasms ; etiology ; metabolism ; Cyclooxygenase 2 ; physiology ; Cytoplasm ; metabolism ; Female ; Male ; Mice ; Mice, Inbred C57BL ; Piroxicam ; pharmacology ; beta Catenin ; metabolism

Objective: The hippocampus is thought to be a vulnerable target of microwave exposure. The aim of the present study was to investigate whether 20-hydroxyecdysone (20E) acted as a fate regulator of adult rat hippocampal neural stem cells (NSCs). Furthermore, we investigated if 20E attenuated high power microwave (HMP) radiation-induced learning and memory deficits. Methods: Sixty male Sprague-Dawley rats were randomly divided into three groups: normal controls, radiation treated, and radiation+20E treated. Rats in the radiation and radiation+20E treatment groups were exposed to HPM radiation from a microwave emission system. The learning and memory abilities of the rats were assessed using the Morris water maze test. Primary adult rat hippocampal NSCs were isolated in vitro and cultured to evaluate their proliferation and differentiation. In addition, hematoxylin & eosin staining, western blotting, and immunofluorescence were used to detect changes in the rat brain and the proliferation and differentiation of the adult rat hippocampal NSCs after HPM radiation exposure. Results: The results showed that 20E induced neuronal differentiation of adult hippocampal NSCs from HPM radiation-exposed rats via the Wnt3a/β-catenin signaling pathway in vitro. Furthermore, 20E facilitated neurogenesis in the subgranular zone of the rat brain following HPM radiation exposure. Administration of 20E attenuated learning and memory deficits in HPM radiation-exposed rats and frizzled-related protein (FRZB) reduced the 20E-induced nuclear translocation of β-catenin, while FRZB treatment also reversed 20E-induced neuronal differentiation of NSCs in vitro. Conclusion These results suggested that 20E was a fate regulator of adult rat hippocampal NSCs, where it played a role in attenuating HPM radiation-induced learning and memory deficits.
Animals ; Cell Proliferation ; Ecdysterone/pharmacology* ; Hippocampus/metabolism* ; Male ; Memory Disorders ; Microwaves ; Neural Stem Cells/physiology* ; Rats ; Rats, Sprague-Dawley ; beta Catenin/metabolism*

OBJECTIVETo inhibit the expression of beta-catenin and investigate the effect of the beta-catenin gene on Jurkat and K562 cells.

METHODSsiRNA specifically knocking down the expression of beta-catenin was used to testify the function of beta-catenin in Jurkat and K562 cells. Real time polymerase chain reaction and Western blot were performed respectively to testify the mRNA level and protein level of beta-catenin. Growth curve was determined by counting viable cells using trypan blue refusal-dyed method. The proliferation of cells was assayed by clonogenic counting and MTT method. The apoptotic cells were measured by Annexin V/PI staining. The cell cycle analysis was performed based on propidium iodide staining.

RESULTSCompared with the control group (transfected with siRNA directed against scramble gene), the survival, colonogenicity, and proliferation of the Jurkat and K562 cells were significantly decreased in experimental group transfected with beta-catenin siRNA. The colonogenicity was decreased from 31.9 +/- 5.55 (siRNA) to 25.0 +/- 5.13 (control) in Jurkat cells, and from 47.33 +/- 8.52 (siRNA) to 39.33 +/- 6.26 (control) in K562 cells (both P <0.05). The inhibition rate was (49.3 +/- 9.86)% (siRNA) and (15.1 +/- 6.55)% (control) respectively in Jurkat cells, and (39.4 +/- 7.56)% (siRNA) and (10.1 +/- 6.89)% (control) in K562 cells (both P <0.05). In addition, the apoptotic rate increased from (23.5 +/- 2.82)% (control group) to (55.9 +/- 2.22)% (experiment group) in Jurkat cells and from (14.9 +/- 8.54)% (control group) to (27.9 +/- 15.3)% (experiment group) in K562 cells. However, cell cycle analysis revealed no obvious phases change both in Jurkat and in K562 cells.

CONCLUSIONKnock-down of beta-catenin gene may decrease the proliferation, survival, and clonogenicity in Jurkat cells and K562 cells.

Apoptosis ; genetics ; physiology ; Blotting, Western ; Cell Cycle ; genetics ; physiology ; Cell Line ; Cell Proliferation ; Humans ; Jurkat Cells ; cytology ; metabolism ; K562 Cells ; cytology ; metabolism ; RNA, Small Interfering ; genetics ; physiology ; Reverse Transcriptase Polymerase Chain Reaction ; beta Catenin ; genetics ; metabolism ; physiology