Introduction: Wnt signaling mechanisms in development and disease

Electroacupuncture promotes neurogenesis in the dentate gyrus and improves pattern separation in an early Alzheimer's disease mouse model

BACKGROUND

Impaired pattern separation occurs in the early stage of Alzheimer's disease (AD), and hippocampal dentate gyrus (DG) neurogenesis participates in pattern separation. Here, we investigated whether spatial memory discrimination impairment can be improved by promoting the hippocampal DG granule cell neogenesis-mediated pattern separation in the early stage of AD by electroacupuncture (EA).

METHODS

Five familial AD mutations (5 × FAD) mice received EA treatment at Baihui and Shenting points for 4 weeks. During EA, mice were intraperitoneally injected with BrdU (50 mg/kg) twice a day. rAAV containing Wnt5a shRNA was injected into the bilateral DG region, and the viral efficiency was evaluated by detecting Wnt5a mRNA levels. Cognitive behavior tests were conducted to assess the impact of EA treatment on cognitive function. The hippocampal DG area Aβ deposition level was detected by immunohistochemistry after the intervention; The number of BrdU+/CaR+ cells and the gene expression level of calretinin (CaR) and prospero homeobox 1(Prox1) in the DG area of the hippocampus was detected to assess neurogenesis by immunofluorescence and western blotting after the intervention; The gene expression levels of FZD2, Wnt5a, DVL2, p-DVL2, CaMKII, and p-CaMKII in the Wnt signaling pathway were detected by Western blotting after the intervention.

RESULTS

Cognitive behavioral tests showed that 5 × FAD mice had impaired pattern separation (P < 0.001), which could be improved by EA (P < 0.01). Immunofluorescence and Western blot showed that the expression of Wnt5a in the hippocampus was decreased (P < 0.001), and the neurogenesis in the DG was impaired (P < 0.001) in 5 × FAD mice. EA could increase the expression level of Wnt5a (P < 0.05) and promote the neurogenesis of immature granule cells (P < 0.05) and the development of neuronal dendritic spines (P < 0.05). Interference of Wnt5a expression aggravated the damage of neurogenesis (P < 0.05), weakened the memory discrimination ability (P < 0.05), and inhibited the beneficial effect of EA (P < 0.05) in AD mice. The expression level of Wnt pathway related proteins such as FZD2, DVL2, p-DVL2, CAMKII, p-CAMKII increased after EA, but the effect of EA was inhibited after Wnt5a was knocked down. In addition, EA could reduce the deposition of Aβ plaques in the DG without any impact on Wnt5a.

CONCLUSION

EA can promote hippocampal DG immature granule cell neogenesis-mediated pattern separation to improve spatial memory discrimination impairment by regulating Wnt5a in 5 × FAD mice.

Bmal1- and Per2-mediated regulation of the osteogenic differentiation and proliferation of mouse bone marrow mesenchymal stem cells by modulating the Wnt/β-catenin pathway

BACKGROUND

Bmal1 and Per2 are the core components of the circadian clock genes (CCGs). Bmal1-/- mice exhibit premature aging, as indicated by hypotrichosis and osteoporosis, with a loss of proliferation ability. The same occurs in Per2-/- mice, albeit to a less severe degree. However, whether the effects of Bmal1 and Per2 on proliferation and osteogenic differentiation are synergistic or antagonistic remains unclear. Thus, our study aimed to explore the effects and specific mechanism.

METHODS AND RESULTS

Lentiviral and adenoviral vectors were constructed to silence or overexpress Bmal1 or Per2 and MTT, flow cytometry, RT-qPCR, WB, immunohistochemistry, alizarin red staining and ChIP-Seq analyses were applied to identify the possible mechanism. The successful knockdown and overexpression of Bmal1/Per2 were detected by fluorescence microcopy. Flow cytometry found out that Bmal1 or Per2 knockdown resulted in G1-phase cell cycle arrest. RT-qPCR showed the different expression levels of Wnt-3a, c-myc1 and axin2 in the Wnt/β-catenin signaling pathway as well as the gene expression change of Rorα and Rev-erbα. Meanwhile, related proteins such as β-catenin, TCF-1, and P-GSK-3β were detected. ALP activity and the amount of mineral nodules were compared. ChIP-Seq results showed the possible mechanism.

CONCLUSIONS

Bmal1 and Per2, as primary canonical clock genes, showed synergistic effects on the proliferation and differentiation of BMSCs. They would inhibit the Wnt/β-catenin signaling pathway by downregulating Rorα expression or upregulating Rev-erbα expression, both of which were also key elements of CCGs. And this may be the mechanism by which they negatively regulate the osteogenic differentiation of BMSCs. Bmal1 and Per2 show synergistic effects in the proliferation of BMSCs. In addition, they play a synergistic role in negatively regulating the osteogenic differentiation ability of BMSCs. Bmal1 and Per2 may regulate the aging of BMSCs by altering cell proliferation and osteogenic differentiation through Rorα and Rev-erbα to affect Wnt/β-catenin pathway.

Loss of endothelial glucocorticoid receptor promotes angiogenesis via upregulation of Wnt/β-catenin pathway

Objective

The glucocorticoid receptor (GR) is a member of the nuclear receptor family that controls key biological processes in the cardiovascular system and has recently been shown to modulate Wnt signaling in endothelial cells. Wnt/β-catenin signaling has been demonstrated to be crucial in the process of angiogenesis. In the current study, we studied whether GR could regulate angiogenesis via the Wnt/β-catenin pathway.

Approach and Resultsa

Key components of the Wnt/β-catenin pathway were evaluated using quantitative PCR and Western blot in the presence or absence of GR. Enhanced angiogenesis was found in GR deficiency in vitro and confirmed with cell viability assays, proliferation assays and tube formation assays. Consistent with these in vitro findings, endothelial cell-specific GR loss GR in vivo promoted angiogenesis in both a hind limb ischemia model and sponge implantation assay. Results were further verified in a novel mouse model lacking endothelial LRP5/6, a key receptor in canonical Wnt signaling, and showed substantially suppressed angiogenesis using these same in vitro and in vivo assays. To further investigate the mechanism of GR regulation of Wnt signaling, autophagy flux was investigated in endothelial cells by visualizing auto phagolysosomes as well as by assessing P62 degradation and LC3B conversion. Results indicated that potentiated autophagy flux participated in GR-Wnt regulation.

Conclusions

Lack of endothelial GR triggers autophagy flux, leads to activation of Wnt/β-catenin signaling and promotes angiogenesis. There may also be a synergistic interaction between autophagy and Wnt/β-catenin signaling.

Supplementary Information

The online version of this article (10.1007/s10456-021-09773-x) contains supplementary material, which is available to authorized users.

BASP1 Suppresses Cell Growth and Metastasis through Inhibiting Wnt/β-Catenin Pathway in Gastric Cancer

Objective

Our research is designed to explore the function of brain acid soluble protein 1 (BASP1) in the progression of gastric cancer (GC) and its underlying molecular mechanisms.

Methods

In this study, the expression of BASP1 was detected by quantitative real-time polymerase chain reaction (qRT-PCR) in both GC tissue and GC cells. The cell cloning, proliferation, apoptosis, migration, and invasion potential of AGS and HGC-27 cells were, respectively, determined using colony formation assay, 5-ethynyl-20-deoxyuridine (EDU) assay, flow cytometry, and Transwell assay. The protein expressions of Bax, caspase-3, Bcl-2, matrix metalloproteinases 2 (MMP-2), MMP-9, Wilms tumor 1 (WT1), Wnt, and β-catenin in AGS and HGC-27 cells were measured by western blot. In addition, the mRNA expressions of WT1, Wnt, and β-catenin in AGS and HGC-27 cells were detected by qRT-PCR.

Results

BASP1 expression was significantly downregulated in both GC tissue and GC cells. BASP1 overexpression markedly repressed proliferation, migration, and invasion and facilitated apoptosis in AGS and HGC-27 cells. In addition, BASP1 overexpression notably promoted the protein expression of Bax and caspase-3 in AGS and HGC-27 cells and inhibited the expression of Bcl-2, MMP-2, and MMP-9. Moreover, BASP1 overexpression significantly inhibited the mRNA and protein expression of WT1, Wnt, and β-catenin in AGS and HGC-27 cells.

Conclusion

BASP1 could significantly suppress cell proliferation, migration, and invasion and promote apoptosis through inhibiting the activation of the Wnt/β-catenin pathway in GC.

LASP2 inhibits trophoblast cell migration and invasion in preeclampsia through inactivation of the Wnt/β-catenin signaling pathway

Preeclampsia (PE) is a specific disorder of pregnancy with significant morbidity and mortality to the mother and the fetus. It has been reported that abnormal regulation of trophoblast cells contributes to the development of PE. LIM and SH3 Protein 2 (LASP2) belongs to nebulin protein family of actin-binding protein that has broad biological functions. In this study, we evaluated the role of LASP2 in the regulation of trophoblast cells. Our results demonstrated that LASP2 was markedly up-regulated in the placentas of patients with PE. Overexpression of LASP2 significantly suppressed the cell proliferation, migration, and invasion of trophoblast cells. LASP2 overexpression reduced the expression levels of β-catenin, cyclin D1, and c-Myc in trophoblast cells. Furthermore, activation of Wnt/β-catenin pathway booked the effects of LASP2 on trophoblast cells. In conclusion, these findings indicated that LASP2 might contribute to the pathogenesis of PE via regulating cell proliferation, migration, and invasion of trophoblast cells. Thus, LASP2 might be a prospective therapeutic target for the prevention and treatment of PE.

LncRNA LOC285194 modulates gastric carcinoma progression through activating Wnt/β-catenin signaling pathway

Emerging evidences have revealed long noncoding RNAs (lncRNAs’) critical roles in diverse human carcinoma. Among these cancers, lncRNA LOC285194 has been extensively investigated in several types of carcinomas in the recent years. Nevertheless, the biological function, clinical relevance, and the influence of LOC285194 in gastric cancer (GC) are not fully understood. The present study aims to explore the biological function of LOC285194 in the progression and development of GC. First, LOC285194 expressions were detected in GC tissues and cell lines. The functional role of LOC285194 in GC was evaluated both in vitro and in vivo. Our data found that LOC285194 was lowly expressed both in human GC tissues and GC cell lines compared with corresponding normal controls. Moreover, LOC285194 was mitigated by transfection with LV‐LOC285194 in both HGC‐27 and MKN45 cell lines. Silencing of LOC285194 remarkably induced GC cell livability and cell proliferation. On the contrary, the LOC285194 overexpression suppressed MKN45 and HGC‐27 cell proliferation and promoted cell apoptosis. Additionally, silencing of LOC285194 increased the ability of colony formation, cell migration, and invasive capacities, together with blocking the apoptotic rates of GC cells. Correspondently, LOC285194 overexpression exerted the opposite effects. Mechanistically, silencing of LOC285194 promoted GC progression via inducing Wnt signaling activity. Moreover, in vivo xenografts nude mice model results showed that LOC285194 inhibited GC progression through targeting Wnt signaling. Taken together, LOC285194 is associated with GC progression by regulating the Wnt signaling transduction, potentiating LOC285194's promising role as a novel treatment biomarker in GC.

LGK974, a PORCUPINE inhibitor, mitigates cytotoxicity in an in vitro model of Parkinson's disease by interfering with the WNT/β-CATENIN pathway

Paraquat (PQ) as an herbicide has been demonstrated to impair dopaminergic (DAergic) neurons and highly correlate with the etiology of Parkinson's disease (PD). WNT/β-CATENIN signaling is known for the specification and neurogenesis of midbrain DAergic neurons and implicated as a therapeutic target in treating many diseases, such as cancer and degenerative diseases. LGK974, a WNT pathway inhibitor, is currently under clinical trial for patients with malignancies. Since the exact role of WNT/β-CATENIN signaling in mediating PD is undetermined, LGK974 was used to examine its effect on the PQ-induced cell model of PD. LGK974 attenuated PQ-induced apoptosis and released mitochondrial pro-poptotic molecules in human neuroblastoma SH-SY5Y cell. PQ increased the levels of β-CATENIN, non-phosphorylated (Ser33/37/Thr41) β-CATENIN, and phosphorylated glycogen synthase kinase (GSK)-3α/β. PQ also increased the nuclear translocation of β-CATENIN, which can be attenuated by LKG974. Furthermore, LGK974 attenuated the PQ-induced release of mitochondrial proapoptotic factors and WNT agonist 1-induced cell death. Taken together, we have shown for the first time that LGK974 mediated through the WNT/β-CATENIN pathway to prevent PQ-induced cell death.

Inhibition of green tea polyphenol EGCG((-)-epigallocatechin-3-gallate) on the proliferation of gastric cancer cells by suppressing canonical wnt/β-catenin signalling pathway

(-)-Epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, could affect carcinogenesis and development of many cancers. However, the effects and underlying mechanisms of EGCG on gastric cancer remain unclear. We found that EGCG significantly inhibited proliferation and increased apoptosis of SGC-7901 cells in vitro. The decreased expressions of p-β-catenin(Ser552), p-GSK3β(S9) and β-catenin target genes were detected in SGC-7901 cells after treated by EGCG. XAV939 and β-catenin plasmid were further used to demonstrate the inhibition of EGCG on canonical Wnt/β-catenin signalling. Moreover, EGCG significantly inhibited gastric tumour growth in vivo by inhibiting Wnt/β-catenin signalling. Taken together, our findings establish that EGCG suppressed gastric cancer cell proliferation and demonstrate that this inhibitory effect is related to canonical Wnt/β-catenin signalling. This study raises a new insight into gastric cancer prevention and therapy, and provides evidence that green tea could be used as a nutraceutical beverage.

Vertebrate spinal commissural neurons: a model system for studying axon guidance beyond the midline

For bilaterally symmetric organisms, the transfer of information between the left and right side of the nervous system is mediated by commissures formed by neurons that project their axons across the body midline to the contralateral side of the central nervous system (CNS). After crossing the midline, many of these axons must travel long distances to reach their targets, including those that extend from spinal commissural neurons. Owing to the highly stereotyped trajectories of spinal commissural neurons that can be divided into several segments as these axons project to their targets, it is an ideal system for investigators to ask fundamental questions related to mechanisms of short- and long-range axon guidance, fasciculation, and choice point decisions at the midline intermediate target. In addition, studies of patterning genes of the nervous system have revealed complex transcription factor codes that function in a combinatorial fashion to specify individual classes of spinal neurons including commissural neurons. Despite these advances and the functional importance of spinal commissural neurons in mediating the transfer of external sensory information from the peripheral nervous system (PNS) to the CNS, only a handful of studies have begun to elucidate the mechanistic logic underlying their long-range pathfinding and the characterization of their synaptic targets. Using in vitro assays, in vivo labeling methodologies, in combination with both loss- and gain-of-function experiments, several studies have revealed that the molecular mechanisms of long-range spinal commissural axon pathfinding involve an interplay between classical axon guidance cues, morphogens and cell adhesion molecules. For further resources related to this article, please visit the WIREs website.