Lung Cancers: Parenchymal Biochemistry and Mechanics.

Parenchyma of pulmonary cancers acquires contractile properties that resemble those of muscles but presents some particularities. These non-muscle contractile tissues could be stimulated either electrically or chemically (KCl). They present the Frank-Starling mechanism, the Hill hyperbolic tension-velocity relationship, and the tridimensional time-independent tension-velocity-length relationship. Relaxation could be obtained by the inhibition of crossbridge molecular motors or by a decrease in the intracellular calcium concentration. They differ from muscles in that their kinetics are ultraslow as evidenced by their low shortening velocity and myosin ATPase activity. Contractility is generated by non-muscle myosin type II A and II B. The activation of the ß-catenin/WNT pathway is accompanied by the high level of the non-muscle myosin observed in lung cancers.

[TIM-3 signaling hijacks the canonical Wnt/ß-catenin pathway to maintain cancer stemness in human acute myeloid leukemia].

Acute myeloid leukemia (AML) is one of the most common hematologic malignancies derived from self-renewing and highly propagating leukemic stem cells (LSCs). We have previously identified T-cell immunoglobulin mucin-3 (TIM-3) as an AML LSC-specific surface molecule by comparing the gene expression profiles of LSCs and hematopoietic stem cells (HSCs). TIM-3 expression clearly discriminates LSCs from HSCs within the CD34+CD38- stem cell fraction. Furthermore, AML cells secrete galectin-9 (Gal-9, a TIM-3 ligand) in an autocrine manner, resulting in constitutive TIM-3 signaling, which maintains LSC self-renewal capacity through ß-catenin accumulation. In this study, we investigated the LSC-specific mechanisms of TIM-3 signaling. We found that TIM-3 signaling drove the canonical Wnt pathway, which was independent of Wnt ligands, to maintain cancer stemness in LSCs. Gal-9 ligation activated the cytoplasmic Src homology 2 (SH2) binding domain of TIM-3 to recruit hematopoietic cell kinase (HCK), a Src family kinase that is highly expressed in LSCs. HCK phosphorylated p120-catenin to promote the formation of the LDL receptor-related protein 6 (LRP6) signalosome, hijacking the canonical Wnt pathway. This TIM-3/HCK/p120-catenin axis was employed principally in immature LSCs compared to TIM-3-expressing exhausted T-cells.

Activation of Wnt/ß­Catenin­p130/E2F4 promotes the differentiation of bone marrow­derived mesenchymal stem cells into type II alveolar epithelial cells through cell cycle arrest.

The results of our previous study demonstrated that activation of the Wnt/ß-catenin pathway increased the differentiation of mesenchymal stem cells (MSCs) into type II alveolar epithelial (AT II) cells; however, the specific mechanisms remain unclear. The present study aimed to evaluate the role of Wnt/ß-catenin-p130/E2F transcription factor 4 (E2F4) in regulating the differentiation of mouse MSCs (mMSCs) into AT II cells, and to determine the specific mechanisms. mMSCs with p130 or E2F4 overexpression were constructed using lentiviral vectors. Differentiation of mMSCs into AT II cells was promoted using a modified coculture system with murine lung epithelial-12 cells incubated in small airway growth medium for 7-14 days. The differentiation efficiency was detected using immunofluorescence, western blot analysis and transmission electron microscopy. To detect the association between the canonical Wnt pathway and p130/E2F4, 4 mmol/l lithium chloride (LiCl) or 200 ng/ml Dickkopf-related protein 1 (DKK-1) was also added to the coculture system. Following differentiation, the cell cycle of mMSCs was evaluated using flow cytometry. The results of the present study demonstrated that surfactant protein C (SP-C) protein expression was higher in the p130 overexpression (MSC-p130) and E2F4 overexpression (MSC-E2F4) groups compared with the normal control mMSCs group following differentiation into AT II cells. Similar results for SP-C protein expression and lamellar body-like structures were also observed using immunofluorescence analysis and electron microscopy. Following the addition of LiCl into the coculture system for activation of the Wnt/ß-catenin signaling pathway, phosphorylated (p)-p130/p130 was slightly decreased at 7 days and E2F4 was increased both at 7 and 14 days in mMSCs. Furthermore, the p-p130/p130 ratio was significantly increased at 14 days and E2F4 was decreased both at 7 and 14 days following DKK-1-mediated inhibition of the Wnt pathway. The results of the present study demonstrated that the numbers of cells in G1 and S phases were increased following activation of the Wnt pathway and decreased following Wnt pathway inhibition. However, the number of cells in G1 phase was increased following the differentiation of mMSCs overexpressing p130 or E2F4. Therefore, the results of the present study revealed that the canonical Wnt signaling pathway may affect the differentiation of MSCs into AT II cells via regulation of downstream p130/E2F4. The specific mechanisms may be associated with G1 phase extension in the cell cycle of MSCs.

IL-27 deficiency inhibits proliferation and invasion of trophoblasts via the SFRP2/Wnt/ß-catenin pathway in fetal growth restriction.

Background: Fetal growth restriction (FGR) is characterized by restricted fetal growth and dysregulated placental development. The etiology and pathogenesis still remain elusive. IL-27 shows multiple roles in regulating various biological processes, however, how IL-27 involves in placentation in FGR pregnancy hasn't been demonstrated. Methods: The levels of IL-27 and IL-27RA in FGR and normal placentae were determined by immunohistochemistry, western blot and RT-PCR. HTR-8/SVneo cells and Il27ra-/- murine models have been adopted to evaluate the effects of IL-27 on the bio-functions of trophoblast cells. GO enrichment and GSEA analysis were performed to explore the underlying mechanism. Findings: IL-27 and IL-27RA was lowly expressed in FGR placentae and administration of IL-27 on HTR-8/SVneo could promote its proliferation, migration and invasion. Comparing with wildtypes, Il27ra-/- embryos were smaller and lighter, and the placentae from which were poorly developed. In mechanism, the molecules of canonical Wnt/ß-catenin pathway (CCND1, CMYC, SOX9) were downregulated in Il27ra-/- placentae. In contrast, the expression of SFRP2 (negative regulator of Wnt) was increased. Overexpression of SFRP2 in vitro could impair trophoblast migration and invasion capacity. Interpretation: IL-27/IL-27RA negatively regulates SFRP2 to activate Wnt/ß-catenin, and thus promotes migration and invasion of trophoblasts during pregnancy. However, IL-27 deficiency may contribute to the development of FGR by restricting the Wnt activity.

A Single Variant in Pri-miRNA-155 Associated with Susceptibility to Hereditary Breast Cancer Promotes Aggressiveness in Breast Cancer Cells.

Variants in genes encoding for microRNAs have been associated with their deregulation in breast cancer (BC). Sequencing of microRNAs deregulated in BC was performed using DNA from Chilean patients with a strong family history and negative for mutations in BRCA1/BRCA2. Seventeen variants were identified, three of which were selected for a case-control association study: rs376491654 (miR-335), rs755634302 (miR-497), and rs190708267 (miR-155). For rs190708267 C>T, the heterozygous T allele was detected in four BC cases and absent in controls, while homozygous TT cases were not detected. Variants were modelled in silico, cloned in a plasmid, expressed in BC cell lines, and functional in vitro assays were performed. Overexpression of the miR-155-T allele increased mature miR-155-5p levels in both BC cell lines, suggesting that its presence alters pre-miR-155 processing. Moreover, BC cells overexpressing the miR-155-T allele showed increased proliferation, migration, and resistance to cisplatin-induced death compared to miR-155-C overexpressing cells. Of note, the 3'UTR of APC, GSK3ß, and PPP1CA genes, all into the canonical Wnt signaling pathway, were identified as direct targets. APC and GSK3ß mRNA levels decreased while PP1 levels increased. These results suggest a pathogenic role of the variant rs190708267 (miR-155) in BRCA 1/2 negative BC, conferring susceptibility and promoting traits of aggressiveness.

Claudin-18 expression under hyperoxia in neonatal lungs of bronchopulmonary dysplasia model rats.

Background: Bronchopulmonary dysplasia (BPD) is characterized by impaired alveolar and microvascular development. Claudin-18 is the only known lung-specific tight junction protein affecting the development and transdifferentiation of alveolar epithelium. Objective: We aimed to explore the changes in the expression of claudin-18, podoplanin, SFTPC, and the canonical WNT pathway, in a rat model of hyperoxia-induced BPD, and to verify the regulatory relationship between claudin-18 and the canonical WNT pathway by cell experiments. Methods: A neonatal rat and cell model of BPD was established by exposing to hyperoxia (85%). Hematoxylin and eosin (HE) staining was used to confirm the establishment of the BPD model. The mRNA levels were assessed using quantitative real-time polymerase chain reaction(qRT-PCR). Protein expression levels were determined using western blotting, immunohistochemical staining, and immunofluorescence. Results: As confirmed by HE staining, the neonatal rat model of BPD was successfully established. Compared to that in the control group, claudin-18 and claudin-4 expression decreased in the hyperoxia group. Expression of ß-catenin in the WNT signaling pathway decreased, whereas that of p-GSK-3ß increased. Expression of the AEC II marker SFTPC initially decreased and then increased, whereas that of the AEC I marker podoplanin increased on day 14 (P < 0.05). Similarly, claudin-18, claudin-4, SFTPC and ß-catenin were decreased but podoplanin was increased when AEC line RLE-6TN exposed to 85% hyperoxia. And the expression of SFTPC was increased, the podoplanin was decreased, and the WNT pathway was upregulated when claudin-18 was overexpressed. Conclusions: Claudin-18 downregulation during hyperoxia might affect lung development and maturation, thereby resulting in hyperoxia-induced BPD. Additionally, claudin-18 is associated with the canonical WNT pathway and AECs transdifferentiation.

Increase in ADAR1p110 activates the canonical Wnt signaling pathway associated with aggressive phenotype in triple negative breast cancer cells.

Triple-negative breast cancer (TNBC) represents a challenge in the search for new therapeutic targets. TNBCs are aggressive and generate resistance to chemotherapy. Tumors of TNBC patients with poor prognosis present a high level of adenosine deaminase acting on RNA1 (ADAR1). We explore the connection of ADAR1 with the canonical Wnt signaling pathway and the effect of modulation of its expression in TNBC. Expression data from cell line sequencing (DepMap) and TCGA samples were downloaded and analyzed. We lentivirally generated an MDA-MB-231 breast cancer cell line that overexpress (OE) ADAR1p110 or an ADAR knockdown. Abundance of different proteins related to Wnt/ß-catenin pathway and activity of nuclear ß-catenin were analyzed by Western blot and luciferase TOP/FOP reporter assay, respectively. Cell invasion was analyzed by matrigel assay. In mice, we study the behavior of tumors generated from ADAR1p110 (OE) cells and tumor vascularization immunostaining were analyzed. ADAR1 connects to the canonical Wnt pathway in TNBC. ADAR1p110 overexpression decreased GSK-3ß, while increasing active ß-catenin. It also increased the activity of nuclear ß-catenin and increased its target levels. ADAR1 knockdown has the opposite effect. MDA-MB-231 ADAR1 (OE) cells showed increased capacity of invasion. Subsequently, we observed that tumors derived from ADAR1p110 (OE) cells showed increased invasion towards the epithelium, and increased levels of Survivin and CD-31 expressed in vascular endothelial cells. These results indicate that ADAR1 overexpression alters the expression of some key components of the canonical Wnt pathway, favoring invasion and neovascularization, possibly through activation of the ß-catenin, which suggests an unknown role of ADAR1p110 in aggressiveness of TNBC tumors.

miR-103-3p targets Ndel1 to regulate neural stem cell proliferation and differentiation.

The regulation of adult neural stem cells (NSCs) is critical for lifelong neurogenesis. MicroRNAs (miRNAs) are a type of small, endogenous RNAs that regulate gene expression post-transcriptionally and influence signaling networks responsible for several cellular processes. In this study, miR-103-3p was transfected into neural stem cells derived from embryonic hippocampal neural stem cells. The results showed that miR-103-3p suppressed neural stem cell proliferation and differentiation, and promoted apoptosis. In addition, miR-103-3p negatively regulated NudE neurodevelopment protein 1-like 1 (Ndel1) expression by binding to the 3' untranslated region of Ndel1. Transduction of neural stem cells with a lentiviral vector overexpressing Ndel1 significantly increased cell proliferation and differentiation, decreased neural stem cell apoptosis, and decreased protein expression levels of Wnt3a, ß-catenin, phosphor-GSK-3ß, LEF1, c-myc, c-Jun, and cyclin D1, all members of the Wnt/ß-catenin signaling pathway. These findings suggest that Ndel1 is a novel miR-103-3p target and that miR-103-3p acts by suppressing neural stem cell proliferation and promoting apoptosis and differentiation. This study was approved by the Animal Ethics Committee of Nantong University, China (approval No. 20200826-003) on August 26, 2020.

Thyroid Hormone Nuclear Receptor TRα1 and Canonical WNT Pathway Cross-Regulation in Normal Intestine and Cancer.

A pivotal role of thyroid hormones and their nuclear receptors in intestinal development and homeostasis have been described, whereas their involvement in intestinal carcinogenesis is still controversial. In this perspective article we briefly summarize the recent advances in this field and present new data regarding their functional interaction with one of the most important signaling pathway, such as WNT, regulating intestinal development and carcinogenesis. These complex interactions unveil new concepts and will surely be of importance for translational research.

Further insights for the role of Morin in mRTBI: Implication of non-canonical Wnt/PKC-α and JAK-2/STAT-3 signaling pathways.

The slightly available data about the pathogenesis process of mild repetitive traumatic brain injury (mRTBI) indicates to the necessity of further exploration of mRTBI consequences. Several cellular changes are believed to contribute to the cognitive disabilities, and neurodegenerative changes observed later in persons subjected to mRTBI. We investigated glial fibrillary acidic protein (GFAP), the important severity related biomarker, where it showed further increase after multiple trauma compared to single one. To authenticate our aim, Morin (10 mg/kg loading dose, then twice daily 5 mg/kg for 7 days), MK-801 (1 mg/kg; i.p) and their combination were used. The results obtained has shown that all the chosen regimens opposed the upregulated dementia markers (Aß1-40,p(Thr231)Tau) and inflammatory protein contents/expression of p(Ser53s6)NF-κBp65, TNF-α, IL-6,and IL-1ß and the elevated GFAP in immune stained cortex sections. Additionally, they exerted anti-apoptotic activity by decreasing caspase-3 activity and increasing Bcl-2 contents. Saving brain tissues was evident after these therapeutic agents via upregulating the non-canonical Wnt-1/PKC-α cue and IL-10/p(Tyr(1007/1008))JAK-2/p(Tyr705)STAT-3 signaling pathway to confirm enhancement of survival pathways on the molecular level. Such results were imitated by correcting the injury dependent deviated behavior, where Morin alone or in combination enhanced behavior outcome. On one side, our study refers to the implication of two survival signaling pathways; viz.,the non-canonical Wnt-1/PKC-α and p(Tyr(1007/1008))JAK-2/p(Tyr705)STAT-3 in single and repetitive mRTBI along with distorted dementia markers, inflammation and apoptotic process that finally disrupted behavior. On the other side, intervention through affecting all these targets by Morin alone or with MK-801 affords a promising neuroprotective effect.

Dickkopf-related protein-1 inhibition attenuates amyloid-beta pathology associated to Alzheimer's disease.

Alzheimer's disease (AD) constitutes the leading cause of dementia worldwide. It is associated to amyloid-ß (Aß) aggregation and tau hyper-phosphorylation, accompanied by a progressive cognitive decline. Evidence suggests that the canonical Wnt pathway is deregulated in AD. Pathway activity is mediated by ß-catenin stabilization in the cytosol, and subsequent translocation to the nucleus to regulate the expression of several genes implicated in brain homeostasis and functioning. It was recently proposed that Dickkopf-related protein-1 (DKK1), an endogenous antagonist of the pathway, might be implicated in AD pathogenesis. Here, we hypothesized that canonical Wnt pathway deactivation associated to DKK1 induction contributes to late-onset AD pathogenesis, and thus DKK1 neutralization could attenuate AD pathology. For this purpose, human post-mortem AD brain samples were used to assess pathway activity, and aged APPswe/PS1 mice were used to investigate DKK1 in late-onset AD-like pathology and therapy. Our findings indicate that ß-catenin levels progressively decrease in the brain of AD patients, correlating with the duration of symptoms. Next, we found that Aß pathology in APPswe/PS1 mediates DKK1 induction in the brain. Pharmacological neutralization of DKK1's biological activity in APPswe/PS1 mice restores pathway activity by stabilizing ß-catenin, attenuates Aß pathology, and ameliorates the memory of mice. Attenuation of AD-like pathology upon DKK1 inhibition is accompanied by a reduced protein expression of beta-site amyloid precursor protein (APP) cleaving enzyme-1 (BACE1). Moreover, DKK1 inhibition enhances vascular density, promotes blood-brain barrier (BBB) integrity by increasing claudin 5, glucose transporter-1 (GLUT1), and ATP-binding cassette sub-family B member-1 (ABCB1) protein expression, as well as ameliorates synaptic plasticity by increasing brain-derived neurotrophic factor (BDNF), and postsynaptic density protein-95 (PSD-95) protein expression. DKK1 conditional induction reduces claudin 5, abcb1, and psd-95 mRNA expression, validating its inhibition effects. Our results indicate that neutralization of DKK1's biological activity attenuates AD-like pathology by restoring canonical Wnt pathway activity.

Hyperactivated Wnt-ß-catenin signaling in the absence of sFRP1 and sFRP5 disrupts trophoblast differentiation through repression of Ascl2.

BACKGROUND: Wnt signaling is a critical determinant for the maintenance and differentiation of stem/progenitor cells, including trophoblast stem cells during placental development. Hyperactivation of Wnt signaling has been shown to be associated with human trophoblast diseases. However, little is known about the impact and underlying mechanisms of excessive Wnt signaling during placental trophoblast development. RESULTS: In the present work, we observed that two inhibitors of Wnt signaling, secreted frizzled-related proteins 1 and 5 (Sfrp1 and Sfrp5), are highly expressed in the extraembryonic trophoblast suggesting possible roles in early placental development. Sfrp1 and Sfrp5 double knockout mice exhibited disturbed trophoblast differentiation in the placental ectoplacental cone (EPC), which contains the precursors of trophoblast giant cells (TGCs) and spongiotrophoblast cells. In addition, we employed mouse models expressing a truncated ß-catenin with exon 3 deletion globally and trophoblast-specifically, as well as trophoblast stem cell lines, and unraveled that hyperactivation of canonical Wnt pathway exhausted the trophoblast precursor cells in the EPC, resulting in the overabundance of giant cells at the expense of spongiotrophoblast cells. Further examination uncovered that hyperactivation of canonical Wnt pathway disturbed trophoblast differentiation in the EPC via repressing Ascl2 expression. CONCLUSIONS: Our investigations provide new insights that the homeostasis of canonical Wnt-ß-catenin signaling is essential for EPC trophoblast differentiation during placental development, which is of high clinical relevance, since aberrant Wnt signaling is often associated with trophoblast-related diseases.

ROS Dependent Wnt/ß-Catenin Pathway and Its Regulation on Defined Micro-Pillars-A Combined In Vitro and In Silico Study.

The physico-chemical surface design of implants influences the surrounding cells. Osteoblasts on sharp-edged micro-topographies revealed an impaired cell phenotype, function and Ca2+ mobilization. The influence of edges and ridges on the Wnt/ß-catenin pathway in combination with the cells' stress response has not been clear. Therefore, MG-63 osteoblasts were studied on defined titanium-coated micro-pillars (5 × 5 × 5 µm) in vitro and in silico. MG-63s on micro-pillars indicated an activated state of the Wnt/ß-catenin pathway. The ß-catenin protein accumulated in the cytosol and translocated into the nucleus. Gene profiling indicated an antagonism mechanism of the transcriptional activity of ß-catenin due to an increased expression of inhibitors like ICAT (inhibitor of ß-catenin and transcription factor-4). Cells on pillars produced a significant reactive oxygen species (ROS) amount after 1 and 24 h. In silico analyses provided a detailed view on how transcriptional activity of Wnt signaling is coordinated in response to the oxidative stress induced by the micro-topography. Based on a coordinated expression of regulatory elements of the Wnt/ß-catenin pathway, MG-63s are able to cope with an increased accumulation of ß-catenin on micro-pillars and suppress an unintended target gene expression. Further, ß-catenin may be diverted into other signaling pathways to support defense mechanisms against ROS.

Local Wnt3a treatment restores bone regeneration in large osseous defects after surgical debridement of osteomyelitis.

Impaired bone homeostasis caused by osteomyelitis provokes serious variations in the bone remodeling process, thereby involving multiple inflammatory cytokines to activate bone healing. We have previously established a mouse model for post-traumatic osteomyelitis and studied bone regeneration after sufficient debridement. Moreover, we could further characterize the postinfectious inflammatory state of bony defects after debridement with elevated osteoclasts and decreased bone formation despite the absence of bacteria. In this study, we investigated the positive effects of Wnt-pathway modulation on bone regeneration in our previous established mouse model. This was achieved by local application of Wnt3a, a recombinant activator of the canonical Wnt-pathway. Application of Wnt3a could enhance new bone formation, which was verified by histological and µ-CT analysis. Moreover, histology and western blots revealed enhanced osteoblastogenesis and downregulated osteoclasts in a RANKL-dependent manner. Further analysis of Wnt-pathway showed downregulation after bone infections were reconstituted by application of Wnt3a. Interestingly, Wnt-inhibitory proteins Dickkopf 1 (DKK1), sclerostin, and secreted frizzled protein 1 (sFRP1) were upregulated simultaneously to Wnt-pathway activation, indicating a negative feedback for active form of Beta-catenin. In this study, we could demonstrate enhanced bone formation in defects caused by post-traumatic osteomyelitis after Wnt3a application. KEY MESSAGES: Osteomyelitis decreases bone regeneration Wnt3a restores bone healing after infection Canonical Wnt-pathway activation with negative feedback.

(Pro)renin receptor accelerates development of sarcopenia via activation of Wnt/YAP signaling axis.

To extend life expectancy and ensure healthy aging, it is crucial to prevent and minimize age-induced skeletal muscle atrophy, also known as sarcopenia. However, the disease's molecular mechanism remains unclear. The age-related Wnt/ß-catenin signaling pathway has been recently shown to be activated by the (pro)renin receptor ((P)RR). We report here that (P)RR expression was increased in the atrophied skeletal muscles of aged mice and humans. Therefore, we developed a gain-of-function model of age-related sarcopenia via transgenic expression of (P)RR under control of the CAG promoter. Consistent with our hypothesis, (P)RR-Tg mice died early and exhibited muscle atrophy with histological features of sarcopenia. Moreover, Wnt/ß-catenin signaling was activated and the regenerative capacity of muscle progenitor cells after cardiotoxin injury was impaired due to cell fusion failure in (P)RR-Tg mice. In vitro forced expression of (P)RR protein in C2C12 myoblast cells suppressed myotube formation by activating Wnt/ß-catenin signaling. Administration of Dickkopf-related protein 1, an inhibitor of Wnt/ß-catenin signaling, and anti-(P)RR neutralizing antibody, which inhibits binding of (P)RR to the Wnt receptor, significantly improved sarcopenia in (P)RR-Tg mice. Furthermore, the use of anti-(P)RR neutralizing antibodies significantly improved the regenerative ability of skeletal muscle in aged mice. Finally, we show that Yes-associated protein (YAP) signaling, which is coordinately regulated by Wnt/ß-catenin, contributed to the development of (P)RR-induced sarcopenia. The present study demonstrates the use of (P)RR-Tg mice as a novel sarcopenia model, and shows that (P)RR-Wnt-YAP signaling plays a pivotal role in the pathogenesis of this disease.

Fibronectin regulates the self-renewal of rabbit limbal epithelial stem cells by stimulating the Wnt11/Fzd7/ROCK non-canonical Wnt pathway.

Microenvironmental factors regulate stem cell fate. Fibronectin (FN), a key extracellular matrix component of the microenvironment, has been linked to various stem cell behaviors. However, how FN controls self-renewal, proliferation, and homeostasis of limbal stem cells remains unclear. Our study investigated the roles of FN in the self-renewal of rabbit limbal epithelial stem cells (rLESCs) by assessing rLESC proliferation and stemness in the presence and absence of FN. We further examined the effect of FN on non-canonical Wnt signaling during rLESC proliferation by evaluating the expression of cell cycle regulators. We found that rLESC proliferation increased after FN treatment and that 12.5 µg/cm2 FN maintained rLESC stemness. FN facilitated rLESC self-renewal by promoting Wnt11 and Fzd7 interaction. Furthermore, FN modulated cell cycle regulators to enhance rLESC proliferation via the upregulation of ROCK1 and ROCK2. Our study provides new insights into the mechanism through which FN regulates the self-renewal of rLESCs; specifically, this occurs via stimulation of the Wnt11/Fzd7/ROCK non-canonical Wnt pathway. The roles of FN in the self-renewal of limbal epithelial stem cells should be further investigated for the potential treatment of limbal deficiency.

Circular RNA SNX29 Sponges miR-744 to Regulate Proliferation and Differentiation of Myoblasts by Activating the Wnt5a/Ca2+ Signaling Pathway.

Myogenesis is a complex and precisely orchestrated process that is highly regulated by several non-coding RNAs and signal pathways. Circular RNAs (circRNAs) represent a novel subclass of endogenous non-coding RNAs that have been identified in multiple species and tissues and play a vital role in post-transcriptional regulation in eukaryotes, but the precise molecular mechanism of action remains largely unknown. Here, we screened a candidate circRNA derived from the SNX29 gene, termed circSNX29 from our previous circRNAs sequencing data of bovine skeletal muscle, and further characterized its regulation and function during muscle development. The overexpression of circSNX29 facilitated myoblasts differentiation and inhibited cell proliferation. Computational analysis using RNAhybrid showed the potential for circSNX29 to sponge to miR-744 with nine potential binding sites. We tested this via a luciferase screening assay and found that circSNX29 directly interacted with miR-744 and downregulation of miR-744 efficiently reversed the suppression of Wnt5a and CaMKIIδ. Importantly, through the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis, Fluo-4, AM, cell permeant-calcium ion fluorescent probing, and western blotting assays, we found that overexpression of Wnt5a and circSNX29 activated the non-canonical Wnt5a/Ca2+ pathway. Overall, the evidence generated by our study elucidates the regulatory mechanisms of circSNX29 to function as a sponge for miRNA-744 in bovine primary myoblasts.

Targeting the canonical Wnt/ß-catenin pathway in cancer radioresistance: Updates on the molecular mechanisms.

Radiation resistance is an important factor that affects the efficacy of radiotherapy; it could even lead to its failure. In recent years, the relationship between the classical Wnt signaling pathway and radiation resistance has gradually attracted attention from scholars. Although most of the findings are comprehensive, they are fragmented and disorganized. This review explores the relationship between classical Wnt signaling pathways and cancer radiation resistance. Previous literature regarding the classical Wnt signaling pathways and cancer radiation resistance from the past decades had been summarized in this article. Moreover, the molecular mechanisms and functions of the canonical Wnt signaling pathway involved in the formation of radioresistance were systemically analyzed and sorted out. Certain rules and internal relationships among different pathways have been further clarified; this is expected to provide valuable clues for further research. The Wnt/ß-catenin pathway is closely associated with the formation of cancer radioresistance, which may be a target for improving the effects of radiotherapy.

Canonical Wnt Pathway Maintains Blood-Brain Barrier Integrity upon Ischemic Stroke and Its Activation Ameliorates Tissue Plasminogen Activator Therapy.

Stroke induces blood-brain barrier (BBB) breakdown, which promotes complications like oedema and hemorrhagic transformation. Administration of recombinant tissue plasminogen activator (rtPA) within a therapeutic time window of 4.5 h after stroke onset constitutes the only existing treatment. Beyond this time window, rtPA worsens BBB breakdown. Canonical Wnt pathway induces BBB formation and maturation during ontogeny. We hypothesized that the pathway is required to maintain BBB functions after stroke; thus, its activation might improve rtPA therapy. Therefore, we first assessed pathway activity in the brain of mice subjected to transient middle cerebral artery occlusion (MCAo). Next, we evaluated the effect of pathway deactivation early after stroke onset on BBB functions. Finally, we assessed the impact of pathway activation on BBB breakdown associated to delayed administration of rtPA. Our results show that pathway activity is induced predominately in endothelial cells early after ischemic stroke. Early deactivation of the pathway using a potent inhibitor, XAV939, aggravates BBB breakdown and increases hemorrhagic transformation incidence. On the other hand, pathway activation using a potent activator, 6-bromoindirubin-3'-oxime (6-BIO), reduces the incidence of hemorrhagic transformation associated to delayed rtPA administration by attenuating BBB breakdown via promotion of tight junction formation and repressing endothelial basal permeability independently of rtPA proteolytic activity. BBB preservation upon pathway activation limited the deleterious effects of delayed rtPA administration. Our study demonstrates that activation of the canonical Wnt pathway constitutes a clinically relevant strategy to extend the therapeutic time window of rtPA by attenuating BBB breakdown via regulation of BBB-specific mechanisms.