Biomedical subjects

Hong Liu

Publications and source records attributed to Hong Liu.

At least 73 records · Page 4Linked to original sources

PubMed2006

Power densities using different cathode catalysts (Pt and CoTMPP) and polymer binders (nafion and PTFE) in single chamber microbial fuel cells.

Cathode catalysts and binders were examined for their effect on power densities in single chamber, air-cathode, microbial fuel cells (MFCs). Chronopotentiometry tests indicated thatthe cathode potential was only slightly reduced (20-40 mV) when Pt loadings were decreased from 2 to 0.1 mg cm(-2), and that Nafion performed better as a Pt binder than poly(tetrafluoroethylene) (PTFE). Replacing the precious-metal Pt catalyst (0.5 mg cm(-2); Nafion binder) with a cobalt material (cobalt tetramethylphenylporphyrin, CoTMPP) produced slightly improved cathode performance above 0.6 mA cm(-2), but reduced performance (<40 mV) at lower current densities. MFC fed batch tests conducted for 35 cycles (31 days) using glucose showed that replacement of the Nafion binder used for the cathode catalyst (0.5 mg of Pt cm(-2)) with PTFE reduced the maximum power densities (from 400 +/- 10 to 480 +/- 20 mW m(-2) to 331 +/- 3 to 360 +/- 10 mW m(-2)). When the Pt loading on cathode was reduced to 0.1 mg cm(-2), the maximum power density of MFC was reduced on average by 19% (379 +/- 5 to 301 +/- 15 mW m(-2); Nafion binder). Power densities with CoTMPP were only 12% (369 +/- 8 mW m(-2)) lower over 25 cycles than those obtained with Pt (0.5 mg cm(-2); Nafion binder). Power densities obtained using with catalysts on the cathodes were approximately 4 times more than those obtained using a plain carbon electrode. These results demonstrate that cathodes used in MFCs can contain very little Pt, and that the Pt can even be replaced with a non-precious metal catalyst such as a CoTMPP with only slightly reduced performance.

Bioelectric Energy Sources↗

PubMed2006

Interleukin-29 uses a type 1 interferon-like program to promote antiviral responses in human hepatocytes.

Interleukin-28A (IL-28A), IL-28B and IL-29 are a family of class II cytokines that stimulate antiviral responses through a heterodimeric receptor that is distinct from the type I interferon (IFN) receptor. To better understand how this newly described family of cytokines regulates the antiviral state, we compared various cellular responses elicited by IL-29 and IFN-alpha. Here we show that these cytokines stimulate similar patterns of signal transducer and activator of transcription 1 (STAT-1), -2, -3, and -5 phosphorylation and nearly identical patterns of gene expression when analyzed in two distinct cell types by microarray analysis. Interestingly, the IL-29 receptor is preferentially expressed on primary hepatocytes within normal liver and pegylated forms of IL-29 and IFN-alpha induced equivalent 2'5' oligoadenylate synthetase (OAS) and MX1 gene expression in this cell type. Pegylated IL-29 also produced a significant reduction in human hepatitis B and hepatitis C viral load in vitro and reduced the cytopathic effect caused by the fully replicating flavivirus, West Nile virus. In conclusion, IL-29 and IFN-alpha stimulate identical antiviral responses despite their utilization of different receptors. This fact, combined with significant receptor expression in hepatitis virus-infected livers, suggests that IL-29 may have therapeutic value against chronic viral hepatitis in human patients.

Animals↗

PubMed2006

Determination of aranidipine and its active metabolite in human plasma by liquid chromatography/negative electrospray ionization tandem mass spectrometry.

A simple, sensitive and rapid high-performance liquid chromatography/negative electrospray ionization tandem mass spectrometry method was developed and validated for the assay of aranidipine (AR) and its active metabolite (AR-M) in human plasma. Following a liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 387.0 --> 164.0 for AR, m/z 389.1 --> 208.1 for AR-M and m/z 359.0 --> 121.8 for the internal standard. The assay exhibited a linear dynamic range of 0.02-10 ng x mL(-1) for AR and 0.2-100 ng x mL(-1) for AR-M in human plasma. The limits of quantitation were 0.02 ng x mL(-1) for AR and 0.2 ng x mL(-1) for AR-M. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.8 min for each sample exhibited its high-throughout analysis ability. The validated method can be applied to analyze human plasma samples for pharmacokinetic studies.

Calcium Channel Blockers↗

PubMed2006

[Effects of hydrodynamic on aggregates formation, growth and metabolism of HEK293 cells in suspension culture].

By using the size distribution of cell aggregates, viable cell density, cell viability, specific consumption rate of glucose (q(glc)), specific production rate of lactate (q(lac)) and lactate transform rate (Y(lac/glc)) as the evaluation indexes, the effects of hydrodynamic on aggregates formation, growth and metabolism of HEK293 cells in suspension culture were examined in 250mL spinner-flasks by setting the agitation rates at 25, 50, 75 and 100r/min, respectively. It was found that agitation plays an important role in HEK293 cell aggregates formation and cell aggregates size distribution. After 7d cultivation in spinner-flasks operated at 50r/min and 75r/min, the average diameter of HEK293 cell aggregates was 201 microm and 175 microm, respectively, with the fraction of aggregates larger than 225 microm less than 10%. The cell viability was kept above 90% with the metabolic indexes, including q(glc), q(lac) and Y(lac/glc) kept constant. These results demonstrated that hydrodynamic derived from the proper agitation play a decisive role in controlling the formation and size distribution of HEK293 cell aggregates, and provided sufficient mass transfer to support the normal growth and metabolism of HEK293 cells in suspended aggregates.

Bioreactors↗

PubMed2006

[In vitro cytolysis of B-lymphoma cells mediated by an anti-CD3/anti-CD20 bispecific single-chain antibody].

After having successfully constructed and expressed the gene of the anti-CD3/anti-CD20 bispecific single-chain antibody (bscCD3 x CD20), here we analyzed its in vitro bioactivity of mediating the lysis of Ramous human B-lymphoma cells in the presence of T-enriched human peripheral blood lymphocytes (PBL). Obvious opoptosis characters were observed by Annexin V/PI(AV/PI) stained and scanning electron microscope. As evaluated by non-radioactive cytotoxity assay, the bscCD3 x CD20 showed potent bioactivity of mediating human B-lymphoma cells lysis in the presence of T-enriched human PBL. The potency of cytotoxicity depended on the ratios of effect cells to target cells (E:T) used. Further, the antibody showed a dose and time-dependent effect on mediating Ramous cells lysis. The specific lysis reached about 87.3% at an antibody concentration of 5microg/mL and E:T used at 10:1. Clear changes in apoptogenes expression profiles were detected by apoptosis gene array after Ramous cells were treated with the antibody and PBL. Among the upregulated apoptogenes, ATM and P53 showed an increase of 187 times and 15 times respectively, which suggested that ATM-p53 pathway may be the main apoptosis way of Ramous cells induced by T cells in the presence of the bscCD3 x CD20.

Antibodies, Bispecific↗

PubMed2006

Composite-hydroxide-mediated approach for the synthesis of nanostructures of complex functional-oxides.

We demonstrate a generic approach for the synthesis of single-crystal complex oxide nanostructures of various structure types, such as perovskites, spinels, monoclinic, corundum, CaF(2) structured, tetragonal, and even metal hydroxides. The method is based on a reaction between a metallic salt and a metallic oxide in a solution of composite-hydroxide eutectic at approximately 200 degrees C and normal atmosphere without using an organic dispersant or capping agent. The synthesis technique is cost-effective, one-step, easy to control, and is performed at low temperature and normal atomospheric pressure. The technique can be expanded to many material systems, and it provides a general, simple, convenient, and innovative strategy for the synthesis of nanostructures of complex oxides with important scientific and technological applications in ferroelectricity, ferromagnetism, colossal magnetoresistance, fuel cell, optics, and more.

Calcium Compounds↗

PubMed2006

Chemical modification modulates estrogenic activity, oxidative reactivity, and metabolic stability in 4'F-DMA, a new benzothiophene selective estrogen receptor modulator.

The benzothiophene selective estrogen receptor modulators (SERMs), raloxifene and arzoxifene, in the clinic or clinical trials for treatment of breast cancer and postmenopausal symptoms, are highly susceptible to oxidative metabolism and formation of electrophilic metabolites. 4'F-DMA, fluoro-substituted desmethyl arzoxifene (DMA), showed attenuated oxidation to quinoids in incubation with rat hepatocytes as well as in rat and human liver microsomes. Incubations of 4'F-DMA with hepatocytes yielded only one glucuronide conjugate and no GSH conjugates, whereas DMA underwent greater metabolism giving two glucuronide conjugates, one sulfate conjugate, and two GSH conjugates. Phase I and phase II metabolism were further evaluated in human small intestine microsomes and in human intestinal Caco-2 cells. In comparison to DMA, 4'F-DMA formed significantly less glucuronide and sulfate conjugates. The formation of quinoids was further explored in hepatocytes in which DMA was observed to give concentration- and time-dependent depletion of GSH accompanied by damage to DNA, which showed inverse dependence on GSH; in contrast, GSH depletion and DNA damage were almost completely abrogated in incubations with 4'F-DMA. 4'F-DMA shows ligand binding affinity to estrogen receptor (ER)alpha and ERbeta with similarity to both raloxifene and to DMA. ER-mediated biological activity was measured with the ERE-luciferase reporter system in transfected MCF-7 cells and Ishikawa cells, and in MCF-7 cells, proliferation was measured. In all systems, 4'F-DMA exhibited anitestrogenic activity of comparable potency to raloxifene but did not manifest estrogenic properties, mirroring previous results on inhibition of estradiol-mediated induction of alkaline phosphatase activity in Ishikawa cells. These results suggest that 4'F-DMA might be an improved benzothiophene SERM with similar antiestrogenic activity to raloxifene but improved metabolic stability and attenuated toxicity, showing that simple chemical modification can abrogate oxidative bioactivation to potentially toxic metabolites without loss of activity.

Animals↗

PubMed2006

Peripherin as a marker for degeneration of spiral ganglion neurons after aminoglycoside ototoxicity.

CONCLUSION: Our data show that temporary appearance of atypical type 1 neurons, like type 3 neurons, might be another degenerating form of spiral ganglion neurons (SGNs); peripherin might be a marker of degenerating neurons. OBJECTIVES: Further morphological and biochemical studies on surviving SGNs after loss of hair cells might offer clues for preventing their degeneration. MATERIALS AND METHODS: We observed the ultrastructural features of surviving SGNs and analyzed the peripherin immunoreactivity at 4, 10, or 20 weeks after systemic injection of neomycin in rats. RESULTS: Type 3 neurons, similar to type 1 neurons but unmyelinated, appeared in the spiral ganglion by 4-week survival, and showed a survival advantage in remaining SGNs by longer surviving periods. We observed neurons packed with dense intermediate filament and with multiple layers of dense myelin sheath (atypical type 1 neurons) in the degenerating neurons. Atypical type 1 neurons were observed among the degenerating neurons in the 4- and 10-week survival groups, but disappeared in longer surviving animals. By means of immunohistochemistry, only smaller SGNs of normal rats were strongly stained by anti-peripherin antibody, whereas increased immunoreactivity was observed in both large and small remaining neurons after neomycin treatment, especially in 10- and 20-week survival animals.

Animals↗

PubMed2006

Th1 bias in PBMC induced by multicycles of auto-CIKs infusion in malignant solid tumor patients.

OBJECTIVE: The aim of this paper was to verify the feasibility and validity of autologous cytokine-induced killer cells (Auto-CIKs) treatments in solid malignancy patients. METHODS: Amplification, phenotypic characteristics, antitumor cytotoxicity, and clinical and immunological response of Auto-CIKs derived from 66 cases of patients with solid tumor of different pathological types and at different clinical stages were examined in a large-scale clinical trail. RESULTS: We found that seriousness of disease and metastasis status has no influence on effective components and antitumor activity of Auto-CIKs. Comparing the cytotoxicity against various tumor cells with LAKs, CIKs showed more effective cytotoxicity against NK sensitive and nonsensitive solid tumor cell lines, even at a low E/T ratio (6:1). In 20 patients receiving multicycles of Auto-CIKs infusions, 3 reached partial response (PR), 14 obtained stable disease (SD), and 3 died. Th1-kind cytokines secretion in peripheral blood mononuclear cells (PBMCs increased significantly, according with the enhanced cytolytic activity against K562 cells of them after multicycles of Auto- CIKs infusions. CONCLUSIONS: Induction of special "Th1 bias" in PBMCs after multicycles of Auto-CIKs treatments suggested an immunological promoting effect of Auto-CIKs, which seems to be a suitable immunotherapy for those solid-malignance patients who are at high risk of relapse to prevent recurrence.

Adolescent↗

PubMed2006

Enhanced cell-free protein expression by fusion with immunoglobulin Ckappa domain.

While cell-free systems are increasingly used for protein expression in structural and functional studies, several proteins are difficult to express or expressed only at low levels in cell-free lysates. Here, we report that fusion of the human immunoglobulin kappa light chain constant domain (Ckappa) at the C terminus of four representative proteins dramatically improved their production in the Escherichia coli S30 system, suggesting that enhancement of cell-free protein expression by Ckappa fusion will be widely applicable.

Cell-Free System↗

PubMed2006

Inhibition of TGF-beta1 expression in human peritoneal mesothelial cells by pcDU6 vector-mediated TGF-beta1 shRNA.

BACKGROUND AND AIM: Transforming growth factor-beta(1) (TGF-beta(1)) is an important mediator of the fibrosis process. High expression of TGF-beta(1) is closely related to peritoneal fibrosis. RNA interference using short hairpin RNA (shRNA) can mediate sequence-specific inhibition of gene expression in mammalian cells. The aim of this study was to assess the effect of shRNA targeting TGF-beta(1) on the expression of TGF-beta(1) in human peritoneal mesothelial cells (HPMC). METHODS: TGF-beta(1) specific shRNA expression vectors were constructed and introduced to HPMC stimulated with 4.25% D-glucose (Gs) and 10 microg/mL of lipopolysaccharide (LPS). Expression of TGF-beta(1) mRNA was assessed by semiquantification reverse transcription polymerase chain reaction (RT-PCR). The TGF-beta(1) protein level in the culture supernatant was determined by sandwich enzyme-linked immunosorbent assay. RESULTS: The expression of TGF-beta(1) was upregulated significantly in HPMC stimulated with 4.25% D-Gs and 10 microg/mL LPS P < 0.01. TGF-beta(1) expression in pcDU6 plasmid vector-mediated TGF-beta(1) shRNA groups were obviously downregulated when compared to the 4.25% D-Gs and 10 microg/mL LPS group (P < 0.01) and the pcDU6 void vector group (P < 0.05), with no significant difference among pcDU6 plasmid vector -mediated TGF-beta(1) shRNA groups (P > 0.05). No significant difference was found between teh pcDNA3.1(-) vector plasmid-mediated TGF-beta(1) antisense RNA group and pcDU6 void vector group (P > 0.05). The expression of TGF-beta(1) in pcDU6 plasmid vector-mediated TGF-beta(1) shRNA groups were obviously downregulated when compared to the pcDNA3.1(-) plasmid vector-mediated TGF-beta(1) antisense RNA group (P < 0.05). CONCLUSION: TGF-beta(1)-specific shRNA can significantly inhibit the expression of TGF-beta(1) in HPMC stimulated with 4.25% D-Gs and 10 microg/mL LPS in HPMC. These results suggest the possible application of TGF-beta(1)-specific shRNA in preventing peritoneal fibrosis in patients receiving peritoneal dialysis.

Epithelial Cells↗

PubMed2006

Troglitazone inhibits synthesis of transforming growth factor-beta1 and reduces matrix production in human peritoneal mesothelial cells.

AIM: Peritoneal matrix accumulation is a characteristic of peritoneal fibrosis (PF). Continuous ambulatory peritoneal dialysis (CAPD) patients with up-regulation of transforming growth factor-beta1 (TGF-beta1) in their drained effluent show an increased risk of PF. Inhibition of TGF-beta1 expression in human peritoneal mesothelial cells (HPMC) may provide a potential treatment for PF. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists are increasingly used in patients with diabetes, but their effects on extracellular matrix (ECM) turnover are unknown. The aims of this study were to investigate the effects of the PPAR-gamma agonist troglitazone on TGF-beta1 expression and matrix production in HPMC. METHODS: Human peritoneal mesothelial cells were cultured from human omentum by an enzyme digestion method, grown in a medium containing 30 mmol/L D-glucose. TGF-beta1 expression and matrix production and turnover were measured in HPMC in the presence and absence of 15 micromol/L troglitazone. The mRNA expressions of TGF-beta(1), Collagen I (Col I) and fibronectin (FN) were determined by semiquantification reverse-transcriptive polymerase chain reaction (RT-PCR). The protein of TGF-beta1 was determined by ELISA and proteins of Col I, FN were determined by western blot. RESULTS: The mRNA expression and protein of TGF-beta(1), Col I, FN were significantly increased in HPMC stimulated with 30 mmol/L D-glucose compared to the control group with F12 media (P < 0.01), which was reversed in the presence of troglitazone (15 micromol/L). Obvious decrease of TGF-beta(1) was found in troglitazone-treated groups as compared to groups stimulated with GS (P < 0.05). Exposure of HPMC to troglitazone reduced collagen I secretion (P < 0.05), and fibronectin secretion (P < 0.05). CONCLUSION: Troglitazone reduce the expression of TGF-beta(1) in HPMC stimulated by 30 mmol/L D-glucose, and reduces ECM production. These studies suggest that the PPAR-gamma agonists may have a specific role in ameliorating the course of progressive peritoneal fibrosis under long-term peritoneal dialysis states.

Blotting, Western↗

PubMed2006

Influence of connective tissue growth factor antisense oligonucleotide on angiotensin II-induced epithelial mesenchymal transition in HK2 cells.

AIM: The present study was designed to further investigate the effect of connective tissue growth factor antisense oligonucleotide (CTGF-AS) on angiotensin II (Ang II)-induced tubular cell epithelial mesenchymal transition (EMT) in vitro. METHODS: The human proximal tubular cell line (HK2) was grown in Dulbecco's modified Eagle's medium containing 10% heat inactivated fetal calf serum. After being rested in serum-free medium for 24 h, the influence of CTGF-AS (20 mug/mL) on Ang II-induced (0.1 micromol/L) CTGF mRNA and the protein expression were examined by using reverse transcription-polymerase chain reaction and indirect-immunofluorescence. The effect of CTGF-AS on Ang II-induced cellular ultrastructure was observed using a transmissive electronic microscope. The expression of alpha-smooth action (alpha-SMA) was assayed by immunocytochemistry. In all experiments, the control group was treated with scrambled oligonucleotide. RESULTS: It was shown that Ang II significantly induced the increasing expression of CTGF mRNA and protein (P<0.01, respectively), which were significantly abolished by treatment with CTGF-AS. After stimulating cells with Ang II, the cellular ultrastructure showed mesenchymal features. These effects were partially inhibited by CTGF-AS. Ang II significantly resulted in the expression of alpha-SMA in time dependent manner, which was markedly attenuated by the treatment with CTGF-AS (P<0.01, respectively). In contrast, no similar effects were observed in the control group treated with scrambled oligonucleotide. CONCLUSION: Ang II-induced EMT in human proximal tubular epithelial cells (PTC) can be attenuated by treatment with CTGF-AS. Our data provides further evidence that CTGF might be involved in Ang II-induced EMT in PTC.

Actins↗

PubMed2006

Design, synthesis and antitumor evaluation of a new series of N-substituted-thiourea derivatives.

AIM: To design and synthesize a novel class of protein tyrosine kinase inhibitors, featuring the N-(2-oxo-1,2-dihydroquinolin-3-yl-methyl)-thiourea framework. METHODS: First, compounds 1 and 2 were identified using the virtual screening approach in conjunction with binding assay based on surface plasmon resonance. Subsequently, 3 regions of compounds 1 and 2 were selected for chemical modification. All compounds were characterized potent inhibitory activities toward the human lung adenocarcinoma cell line SPAC1. RESULTS: Forty new compounds (1-2, 3a-g, 4a-w, and 5a-l) were designed, synthesized and bioassayed. Six compounds (1, 3e, 4l, 4w, 5a, and 5b) were found to show promising inhibitory activity against the SPAC1 tumor cell line. The inhibitory activity of compound 5a increases approximately 10 times more than that of the original compound 1. CONCLUSION: This study provides a promising new template with potential antitumor activity.

Adenocarcinoma↗

PubMed2006

Conversion of Sphingobium chlorophenolicum ATCC 39723 to a hexachlorobenzene degrader by metabolic engineering.

The gene cassette (camA+ camB+ camC) encoding a cytochrome P-450cam variant was integrated into the nonessential gene pcpM of the pentachlorophenol degrader Sphingobium chlorophenolicum ATCC 39723 by homologous recombination. The recombinant strain could degrade hexachlorobenzene at a rate of 0.67 nmol.mg (dry weight)-1.h-1, and intermediate pentachlorophenol was also identified.

Bacterial Proteins↗

PubMed2006

Inactivation of a two-component signal transduction system, SaeRS, eliminates adherence and attenuates virulence of Staphylococcus aureus.

Staphylococcus aureus is a major human and animal pathogen. During infection, this organism not only is able to attach to and enter host cells by using its cell surface-associated factors but also exports toxins to induce apoptosis and kill invaded cells. In this study, we identified the regulon of a two-component signal transduction system, SaeRS, and demonstrated that the SaeRS system is required for S. aureus to cause infection both in vitro and in vivo. Using microarray and real-time reverse transcriptase PCR analyses, we found that SaeRS regulates the expression of genes involved in adhesion and invasion (such as those encoding fibronectin-binding proteins and fibrinogen-binding proteins) and genes encoding alpha-, beta-, and gamma-hemolysins. Surprisingly, we found that SaeRS represses the Agr regulatory system since the mutation of saeS up-regulates agrA expression, which was confirmed by using an agr promoter-reporter fusion system. More importantly, we demonstrated that inactivation of the SaeRS system significantly decreases the bacterium-induced apoptosis and/or death of lung epithelial cells (A549) and attenuates virulence in a murine infection model. Moreover, we found that inactivation of the SaeRS system eliminates staphylococcal adhesion and internalization of lung epithelial cells. We also found that both a novel hypothetical protein (the SA1000 protein) and a bifunctional protein (Efb), which binds to extracellular fibrinogen and complement factor C3, might partially contribute to bacterial adhesion to and invasion of epithelial cells. Our results indicate that activation of the SaeRS system may be required for S. aureus to adhere to and invade epithelial cells.

Animals↗

PubMed2006

Cooperative activity of BRG1 and Z-DNA formation in chromatin remodeling.

The mammalian genome contains tens of thousands of CG and TG repeat sequences that have high potential to form the nonclassical left-handed double-helical Z-DNA structure. Previously we showed that activation of the colony-stimulating factor 1 (CSF1) gene by the chromatin remodeling enzyme, BRG1, results in formation of Z-DNA at the TG repeat sequence located within the promoter. In this report, we show that the TG repeats are assembled in a positioned nucleosome in the silent CSF1 promoter and that activation by BRG1 disrupts this nucleosome and results in Z-DNA formation. Active transcription is not required for the formation of Z-DNA but does result in an expanded region of Z-DNA. Formation of sequences by both BRG1 and the Z-DNA is required for effective chromatin remodeling of the CSF1 promoter. We propose the Z-DNA formation induced by BRG1 promotes a transition from a transient and partial remodeling to a more extensive disruption of the canonical nucleosomal structure. The data presented in this report establish that Z-DNA formation is an important mechanism in modulating chromatin structure, in similarity to the activities of ATP-dependent remodelers and posttranslational histone modifications.

Cells, Cultured↗

PubMed2006

Mapping canonical Wnt signaling in the developing and adult retina.

PURPOSE: The role of the Wnt[b]/beta-catenin-dependent pathway (canonical Wnt pathway) in the context of retinal development and homeostasis is largely unknown. This study was undertaken to characterize activation of the Wnt canonical pathway and its relevance to cell type populations in the developing and adult retina. METHODS: Tissue from TCF/Lef-LacZ (T-cell-specific transcription factor/lymphoid enhancer-binding factor) transgenic mice was used for monitoring the activation of the canonical Wnt pathway. Lithium (Li(+)) treatment was applied to induce ectopic activation of the TCF/Lef-LacZ reporter gene in retinal explants. Gene expression and retinal cell types were examined by in situ hybridization (ISH) or by immunohistochemistry (IHC). RESULTS: On Li(+) treatment, ectopic expression of the TCF/Lef-LacZ reporter gene was rapidly and dramatically induced in retinal explants. The pattern of TCF/Lef-LacZ reporter gene expression was dynamic throughout retinal development and in the adult retina. There was a distinctive expression pattern in each cellular layer, in the developing ciliary margin (CM), and the prospective ciliary epithelium. In the mature retina, the TCF/Lef-LacZ reporter gene was expressed in subsets of retinal ganglion cells (RGCs) and amacrine cells. The expression of the four TCF/Lef transcription factors overlapped with activation of the TCF/Lef-LacZ reporter. CONCLUSIONS: The TCF/Lef-LacZ transgene is a faithful reporter of canonical Wnt signaling in the retina. The pattern of TCF/Lef-LacZ reporter gene activation and of TCF/Lef transcription factor expression suggests that activation of the canonical Wnt pathway is developmental-stage dependent and is spatially modulated. Our findings also imply the involvement of this pathway in the specification and/or generation of ciliary epithelium, cellular differentiation, axon guidance, and connectivity to targets in the central nervous system and in the maintenance or function of specific retinal neurons in the adult.

Animals↗