Wnt7b activates canonical signaling in epithelial and vascular smooth muscle cells through interactions with Fzd1, Fzd10, and LRP5

Basic Fibroblast Growth Factor Supports the Function of Limbal Niche Cells via the Wnt/β-Catenin Pathway

Purpose: To test the effects and underlying mechanisms of basic fibroblast growth factor (bFGF) on the limbal niche cell (LNC) function ex vivo. Methods: By using different concentrations of bFGF (0, 4, 8, 12, and 16 ng/mL) and fibroblast growth factor receptor (FGFR) inhibitors, the effects of bFGF on LNC proliferation, expression of stem cell markers, and transcription levels of the β-catenin were investigated. Single-cell RNA sequencing (scRNA-seq) was used to analyze the action and mechanisms of FGFR subtypes and the Wnt/β-catenin pathway during LNC culture. An mature corneal epithelial cell (MCEC)/LNC three-dimensional model was constructed to verify whether bFGF activates the Wnt/β-catenin pathway in LNC by inhibiting FGFR or β-catenin targets. Results: scRNA-seq showed that FGFR1 is the main receptor in LNC, along with the molecules in the Wnt pathway, including WNT2, FZD7, LRP5, LRP6, and β-catenin. The 12 ng/mL bFGF treatment group showed higher LNC proliferation rate and transcription levels of OCT4, SOX2, NANOG, and β-catenin than any other groups (P < 0.001). In the MCEC/LNC co-culture model, MCEC/LNC treated with 12 ng/mL bFGF promoted the aggregation of the spheres than other groups, associated with increased transcription levels of P63α, WNT2, β-catenin, and a decreased transcription level of CK12 (P < 0.001). Wnt/β-catenin inhibitor LF3 treatment reversed the abovementioned effect of bFGF. Conclusions: bFGF could maintain and promote the stemness of LNC via the FGFR1/Wnt2/FZD7/LRP6 axis in a concentration-dependent manner.

Emerging biological functions of Twist1 in cell differentiation

Twist1 is required for embryonic development and expresses after birth in mesenchymal stem cells derived from mesoderm, where it governs mesenchymal cell development. As a well-known regulator of epithelial-mesenchymal transition or embryonic organogenesis, Twist1 is important in a variety of developmental systems, including mesoderm formation, neurogenesis, myogenesis, cranial neural crest cell migration, and differentiation. In this review, we first highlight the physiological significance of Twist1 in cell differentiation, including osteogenic, chondrogenic, and myogenic differentiation, and then detail its probable molecular processes and signaling pathways. On this premise, we summarize the significance of Twist1 in distinct developmental disorders and diseases to provide a reference for studies on cell differentiation/development-related diseases.

Inhibiting histone deacetylase 6 suppresses the proliferation of microvascular endothelial cells by epigenetically activating miR-375-3p, potentially contributing to bone loss during mechanical unloading

BACKGROUND

Mechanical unloading-induced bone loss threatens prolonged spaceflight and human health. Recent studies have confirmed that osteoporosis is associated with a significant reduction in bone microvessels, but the relationship between them and the underlying mechanism under mechanical unloading are still unclear.

METHODS

We established a 2D clinostat and hindlimb-unloaded (HLU) mouse model to simulate unloading in vitro and in vivo. Micro-CT scanning was performed to assess changes in the bone microstructure and mass of the tibia. The levels of CD31, Endomucin (EMCN) and histone deacetylase 6 (HDAC6) in tibial microvessels were detected by immunofluorescence (IF) staining. In addition, we established a coculture system of microvascular endothelial cells (MVECs) and osteoblasts, and qRT‒PCR or western blotting was used to detect RNA and protein expression; cell proliferation was detected by CCK‒8 and EdU assays. ChIP was used to detect whether HDAC6 binds to the miRNA promoter region.

RESULTS

Bone mass and bone microvessels were simultaneously significantly reduced in HLU mice. Furthermore, MVECs effectively promoted the proliferation and differentiation of osteoblasts under coculture conditions in vitro. Mechanistically, we found that the HDAC6 content was significantly reduced in the bone microvessels of HLU mice and that HDAC6 inhibited the expression of miR-375-3p by reducing histone acetylation in the miR-375 promoter region in MVECs. miR-375-3p was upregulated under unloading and it could inhibit MVEC proliferation by directly targeting low-density lipoprotein-related receptor 5 (LRP5) expression. In addition, silencing HDAC6 promoted the miR-375-3p/LRP5 pathway to suppress MVEC proliferation under mechanical unloading, and regulation of HDAC6/miR-375-3p axis in MVECs could affect osteoblast proliferation under coculture conditions.

CONCLUSION

Our study revealed that disuse-induced bone loss may be closely related to a reduction in the number of bone microvessels and that the modulation of MVEC function could improve bone loss induced by unloading. Mechanistically, the HDAC6/miR-375-3p/LRP5 pathway in MVECs might be a promising strategy for the clinical treatment of unloading-induced bone loss.

The importance of the circRNA/Wnt axis in gliomas: Biological functions and clinical opportunities

Gliomas are among the most common cancers in the central nervous system, arising through various signaling pathways. One significant pathway is Wnt signaling, a tightly regulated process that plays a crucial role in gliomagenesis and development. The current study aims to explore the relationship between circular RNAs (circRNAs) and the Wnt/β-catenin signaling pathway in gliomas, considering the growing recognition of circRNAs in disease pathogenesis. A comprehensive review of recent research was conducted to investigate the roles of circRNAs in gliomas, focusing on their expression patterns and interactions with the Wnt signaling pathway. The analysis included studies examining circRNAs' function as microRNA sponges and their impact on glioma biology. The findings reveal that circRNAs are differentially expressed in gliomas and significantly influence the occurrence, growth, and metastasis of these tumors. Specifically, circRNAs interact with the Wnt signaling pathway, affecting glioma development and progression. This interaction highlights the importance of circRNAs in glioma pathophysiology. Understanding the regulatory network involving circRNAs and Wnt signaling offers valuable insights into glioma pathophysiology. CircRNAs hold promise as diagnostic and prognostic biomarkers and may serve as targets for novel therapeutic strategies in glioma treatment.

Methylome analysis of endothelial cells suggests new insights on sporadic brain arteriovenous malformation

Arteriovenous malformation of the brain (bAVM) is a vascular phenotype related to brain defective angiogenesis. Involved vessels show impaired expression of vascular differentiation markers resulting in the arteriolar to venule direct shunt. In order to clarify aberrant gene expression occurring in bAVM, here we describe results obtained by methylome analysis performed on endothelial cells (ECs) isolated from bAVM specimens, compared to human cerebral microvascular ECs. Results were validated by quantitative methylation-specific PCR and quantitative realtime-PCR. Differential methylation events occur in genes already linked to bAVM onset, as RBPJ and KRAS. However, among differentially methylated genes, we identified EPHB1 and several other loci involved in EC adhesion as well as in EC/vascular smooth muscle cell (VSMC) crosstalk, suggesting that only endothelial dysfunction might not be sufficient to trigger the bAVM phenotype. Moreover, aberrant methylation pattern was reported for many lncRNA genes targeting transcription factors expressed during neurovascular development. Among these, the YBX1 that was recently shown to target the arteridin coding gene. Finally, in addition to the conventional CpG methylation, we further considered the role of impaired CHG methylation, mainly occurring in brain at embryo stage. We showed as differentially CHG methylated genes are clustered in pathways related to EC homeostasis, as well as to VSMC-EC crosstalk, suggesting as impairment of this interaction plays a prominent role in loss of vascular differentiation, in bAVM phenotype.

Advances in Regenerative Dentistry: A Systematic Review of Harnessing Wnt/β-Catenin in Dentin-Pulp Regeneration

Dentin pulp has a complex function as a major unit in maintaining the vitality of teeth. In this sense, the Wnt/β-Catenin pathway has a vital part in tooth development, maintenance, repair, and regeneration by controlling physiological activities such as growth, differentiation, and migration. This pathway consists of a network of proteins, such as Wnt signaling molecules, which interact with receptors of targeted cells and play a role in development and adult tissue homeostasis. The Wnt signals are specific spatiotemporally, suggesting its intricate mechanism in development, regulation, repair, and regeneration by the formation of tertiary dentin. This review provides an overview of the recent advances in the Wnt/β-Catenin signaling pathway in dentin and pulp regeneration, how different proteins, molecules, and ligands influence this pathway, either upregulating or silencing it, and how it may be used in the future for clinical dentistry, in vital pulp therapy as an effective treatment for dental caries, as an alternative approach for root canal therapy, and to provide a path for therapeutic and regenerative dentistry.

Non-canonical Wnt signaling in the eye

Wnt signaling comprises a group of complex signal transduction pathways that play critical roles in cell proliferation, differentiation, and apoptosis during development, as well as in stem cell maintenance and adult tissue homeostasis. Wnt pathways are classified into two major groups, canonical (β-catenin-dependent) or non-canonical (β-catenin-independent). Most previous studies in the eye have focused on canonical Wnt signaling, and the role of non-canonical signaling remains poorly understood. Additionally, the crosstalk between canonical and non-canonical Wnt signaling in the eye has hardly been explored. In this review, we present an overview of available data on ocular non-canonical Wnt signaling, including developmental and functional aspects in different eye compartments. We also discuss important changes of this signaling in various ocular conditions, such as keratoconus, aniridia-related keratopathy, diabetes, age-related macular degeneration, optic nerve damage, pathological angiogenesis, and abnormalities in the trabecular meshwork and conjunctival cells, and limbal stem cell deficiency.

The tissue-specific transcriptional landscape underlines the involvement of endothelial cells in health and disease

Endothelial cells (ECs) that line vascular and lymphatic vessels are being increasingly recognized as important to organ function in health and disease. ECs participate not only in the trafficking of gases, metabolites, and cells between the bloodstream and tissues but also in the angiocrine-based induction of heterogeneous parenchymal cells, which are unique to their specific tissue functions. The molecular mechanisms regulating EC heterogeneity between and within different tissues are modeled during embryogenesis and become fully established in adults. Any changes in adult tissue homeostasis induced by aging, stress conditions, and various noxae may reshape EC heterogeneity and induce specific transcriptional features that condition a functional phenotype. Heterogeneity is sustained via specific genetic programs organized through the combinatory effects of a discrete number of transcription factors (TFs) that, at the single tissue-level, constitute dynamic networks that are post-transcriptionally and epigenetically regulated. This review is focused on outlining the TF-based networks involved in EC specialization and physiological and pathological stressors thought to modify their architecture.

Bi-allelic variants in WNT7B disrupt the development of multiple organs in humans

BACKGROUND

Pulmonary hypoplasia, Diaphragmatic anomalies, Anophthalmia/microphthalmia and Cardiac defects delineate the PDAC syndrome. We aim to identify the cause of PDAC syndrome in patients who do not carry pathogenic variants in RARB and STRA6, which have been previously associated with this disorder.

METHODS

We sequenced the exome of patients with unexplained PDAC syndrome and performed functional validation of candidate variants.

RESULTS

We identified bi-allelic variants in WNT7B in fetuses with PDAC syndrome from two unrelated families. In one family, the fetus was homozygous for the c.292C>T (p.(Arg98*)) variant whereas the fetuses from the other family were compound heterozygous for the variants c.225C>G (p.(Tyr75*)) and c.562G>A (p.(Gly188Ser)). Finally, a molecular autopsy by proxy in a consanguineous couple that lost two babies due to lung hypoplasia revealed that both parents carry the p.(Arg98*) variant. Using a WNT signalling canonical luciferase assay, we demonstrated that the identified variants are deleterious. In addition, we found that wnt7bb mutant zebrafish display a defect of the swimbladder, an air-filled organ that is a structural homolog of the mammalian lung, suggesting that the function of WNT7B has been conserved during evolution for the development of these structures.

CONCLUSION

Our findings indicate that defective WNT7B function underlies a form of lung hypoplasia that is associated with the PDAC syndrome, and provide evidence for involvement of the WNT-β-catenin pathway in human lung, tracheal, ocular, cardiac, and renal development.

WNT5A-RHOA Signaling Is a Driver of Tumorigenesis and Represents a Therapeutically Actionable Vulnerability in Small Cell Lung Cancer

WNT signaling represents an attractive target for cancer therapy due to its widespread oncogenic role. However, the molecular players involved in WNT signaling and the impact of their perturbation remain unknown for numerous recalcitrant cancers. Here, we characterize WNT pathway activity in small cell lung cancer (SCLC) and determine the functional role of WNT signaling using genetically engineered mouse models. β-Catenin, a master mediator of canonical WNT signaling, was dispensable for SCLC development, and its transcriptional program was largely silenced during tumor development. Conversely, WNT5A, a ligand for β-catenin-independent noncanonical WNT pathways, promoted neoplastic transformation and SCLC cell proliferation, whereas WNT5A deficiency inhibited SCLC development. Loss of p130 in SCLC cells induced expression of WNT5A, which selectively increased Rhoa transcription and activated RHOA protein to drive SCLC. Rhoa knockout suppressed SCLC development in vivo, and chemical perturbation of RHOA selectively inhibited SCLC cell proliferation. These findings suggest a novel requirement for the WNT5A-RHOA axis in SCLC, providing critical insights for the development of novel therapeutic strategies for this recalcitrant cancer. This study also sheds light on the heterogeneity of WNT signaling in cancer and the molecular determinants of its cell-type specificity.

SIGNIFICANCE

The p130-WNT5A-RHOA pathway drives SCLC progression and is a potential target for the development of therapeutic interventions and biomarkers to improve patient treatment.

Genome-Wide Association Study of Adhesive Capsulitis Suggests Significant Genetic Risk Factors

BACKGROUND

Adhesive capsulitis of the shoulder involves loss of passive range of motion with associated pain and can develop spontaneously, with no obvious injury or inciting event. The pathomechanism of this disorder remains to be elucidated, but known risk factors for adhesive capsulitis include diabetes, female sex, and thyroid dysfunction. Additionally, transcriptional profiling and pedigree analyses have suggested a role for genetics. Identification of elements of genetic risk for adhesive capsulitis using population-based techniques can provide the basis for guiding both the personalized treatment of patients based on their genetic profiles and the development of new treatments by identification of the pathomechanism.

METHODS

A genome-wide association study (GWAS) was conducted using the U.K. Biobank (a collection of approximately 500,000 patients with genetic data and associated ICD-10 [International Classification of Diseases, 10th Revision] codes), comparing 2,142 patients with the ICD-10 code for adhesive capsulitis (M750) to those without. Separate GWASs were conducted controlling for 2 of the known risk factors of adhesive capsulitis-hypothyroidism and diabetes. Logistic regression analysis was conducted controlling for factors including sex, thyroid dysfunction, diabetes, shoulder dislocation, smoking, and genetics.

RESULTS

Three loci of significance were identified: rs34315830 (in WNT7B; odds ratio [OR] = 1.28; 95% confidence interval [CI], 1.22 to 1.39), rs2965196 (in MAU2; OR = 1.67; 95% CI, 1.39 to 2.00), and rs1912256 (in POU1F1; OR = 1.22; 95% CI, 1.14 to 1.31). These loci retained significance when controlling for thyroid dysfunction and diabetes. The OR for total genetic risk was 5.81 (95% CI, 4.08 to 8.31), compared with 1.70 (95% CI, 1.18 to 2.36) for hypothyroidism and 4.23 (95% CI, 2.32 to 7.05) for diabetes.

CONCLUSIONS

The total genetic risk associated with adhesive capsulitis was significant and similar to the risks associated with hypothyroidism and diabetes. Identification of WNT7B, POU1F1, and MAU2 implicates the Wnt pathway and cell proliferation response in the pathomechanism of adhesive capsulitis.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Regulatory role of miRNAs in Wnt signaling pathway linked with cardiovascular diseases

MicroRNAs (miRNAs) are discovered in science about 23 years ago. These are short, a series of non-coding, single-stranded and evolutionary conserved RNA molecules found in eukaryotic cells. It involved post-transcriptional fine-tune protein expression and repressing the target of mRNA in different biological processes. These miRNAs binds with the 3'-UTR region of specific mRNAs to phosphorylate the mRNA degradation and inhibit the translation process in various tissues. Therefore, aberrant expression in miRNAs induces numerous cardiovascular diseases and developmental defects. Subsequently, the miRNAs and Wnt singling pathway are regulating a cellular process in cardiac development and regeneration, maintain the homeostasis and associated heart diseases. In Wnt signaling pathway majority of the signaling components are expressed and regulated by miRNAs, whereas the inhibition or dysfunction of the Wnt signaling pathway induces cardiovascular diseases. Moreover, inadequate studies about the important role of miRNAs in heart development and diseases through Wnt signaling pathway has been exist still now. For this reason in present review we summarize and update the involvement of miRNAs and the role of Wnt signaling in cardiovascular diseases. We have discussed the mechanism of miRNA functions which regulates the Wnt components in cellular signaling pathway. The fundamental understanding of Wnt signaling regulation and mechanisms of miRNAs is quite essential for study of heart development and related diseases. This approach definitely enlighten the future research to provide a new strategy for formulation of novel therapeutic approaches against cardiovascular diseases.

Wnt Signaling in Vascular Calcification

Cardiovascular disease is a worldwide epidemic and considered the leading cause of death globally. Due to its high mortality rates, it is imperative to study the underlying causes and mechanisms of the disease. Vascular calcification, or the buildup of hydroxyapatite within the arterial wall, is one of the greatest contributors to cardiovascular disease. Medial vascular calcification is a predictor of cardiovascular events such as, but not limited to, hypertension, stiffness, and even heart failure. Vascular smooth muscle cells (VSMCs), which line the arterial wall and function to maintain blood pressure, are hypothesized to undergo a phenotypic switch into bone-forming cells during calcification, mimicking the manner by which mesenchymal stem cells differentiate into osteoblast cells throughout osteogenesis. RunX2, a transcription factor necessary for osteoblast differentiation and a target gene of the Wnt signaling pathway, has also shown to be upregulated when calcification is present, implicating that the Wnt cascade may be a key player in the transdifferentiation of VSMCs. It is important to note that the phenotypic switch of VSMCs from a healthy, contractile state to a proliferative, synthetic state is necessary in response to the vascular injury surrounding calcification. The lingering question, however, is if VSMCs acquire this synthetic phenotype through the Wnt pathway, how and why does this signaling occur? This review seeks to highlight the potential role of the canonical Wnt signaling pathway within vascular calcification based on several studies and further discuss the Wnt ligands that specifically aid in VSMC transdifferentiation.

YAP regulates alveolar epithelial cell differentiation and AGER via NFIB/KLF5/NKX2-1

Ventilation is dependent upon pulmonary alveoli lined by two major epithelial cell types, alveolar type-1 (AT1) and 2 (AT2) cells. AT1 cells mediate gas exchange while AT2 cells synthesize and secrete pulmonary surfactants and serve as progenitor cells which repair the alveoli. We developed transgenic mice in which YAP was activated or deleted to determine its roles in alveolar epithelial cell differentiation. Postnatal YAP activation increased epithelial cell proliferation, increased AT1 cell numbers, and caused indeterminate differentiation of subsets of alveolar cells expressing atypical genes normally restricted to airway epithelial cells. YAP deletion increased expression of genes associated with mature AT2 cells. YAP activation enhanced DNA accessibility in promoters of transcription factors and motif enrichment analysis predicted target genes associated with alveolar cell differentiation. YAP participated with KLF5, NFIB, and NKX2-1 to regulate AGER. YAP plays a central role in a transcriptional network that regulates alveolar epithelial differentiation.

Wnt/β-catenin signaling in cancers and targeted therapies

Wnt/β-catenin signaling has been broadly implicated in human cancers and experimental cancer models of animals. Aberrant activation of Wnt/β-catenin signaling is tightly linked with the increment of prevalence, advancement of malignant progression, development of poor prognostics, and even ascendence of the cancer-associated mortality. Early experimental investigations have proposed the theoretical potential that efficient repression of this signaling might provide promising therapeutic choices in managing various types of cancers. Up to date, many therapies targeting Wnt/β-catenin signaling in cancers have been developed, which is assumed to endow clinicians with new opportunities of developing more satisfactory and precise remedies for cancer patients with aberrant Wnt/β-catenin signaling. However, current facts indicate that the clinical translations of Wnt/β-catenin signaling-dependent targeted therapies have faced un-neglectable crises and challenges. Therefore, in this study, we systematically reviewed the most updated knowledge of Wnt/β-catenin signaling in cancers and relatively targeted therapies to generate a clearer and more accurate awareness of both the developmental stage and underlying limitations of Wnt/β-catenin-targeted therapies in cancers. Insights of this study will help readers better understand the roles of Wnt/β-catenin signaling in cancers and provide insights to acknowledge the current opportunities and challenges of targeting this signaling in cancers.

Reduced Oligodendrocyte Precursor Cell Impairs Astrocytic Development in Early Life Stress

Astrocyte maldevelopment is implicated in various neuropsychiatric diseases associated with early life stress. However, the underlying astrocytopathy mechanism, which can result in the psychiatric symptoms, remains unclear. In this study, it is shown that a reduced oligodendrocyte precursor cell (OPC) population accompanies hindered hippocampal astrocytic development in an improved parental isolation mouse model, and that the loss of OPCs suppresses astrocytic network formation and activity. It is further demonstrated that OPC-derived Wnt ligands, in particular Wnt7b, are required for Wnt/β-catenin pathway-mediated astrocytic development and subsequent effects related to neuronal function. In addition, focal replenishment of Wnt7a/b is sufficient to rescue astrocytic maldevelopment. These results elucidate a Wnt-paracrine-dependent but myelin-independent role of OPCs in regulating astrocytic development, which provides a unique insight into the astrocytopathy mechanism in early life stress, and can be implicated in the pathogenesis of human early life stress-related neuropsychiatric disorders.

Evolutionary Perspective and Expression Analysis of Intronless Genes Highlight the Conservation of Their Regulatory Role

The structure of eukaryotic genes is generally a combination of exons interrupted by intragenic non-coding DNA regions (introns) removed by RNA splicing to generate the mature mRNA. A fraction of genes, however, comprise a single coding exon with introns in their untranslated regions or are intronless genes (IGs), lacking introns entirely. The latter code for essential proteins involved in development, growth, and cell proliferation and their expression has been proposed to be highly specialized for neuro-specific functions and linked to cancer, neuropathies, and developmental disorders. The abundant presence of introns in eukaryotic genomes is pivotal for the precise control of gene expression. Notwithstanding, IGs exempting splicing events entail a higher transcriptional fidelity, making them even more valuable for regulatory roles. This work aimed to infer the functional role and evolutionary history of IGs centered on the mouse genome. IGs consist of a subgroup of genes with one exon including coding genes, non-coding genes, and pseudogenes, which conform approximately 6% of a total of 21,527 genes. To understand their prevalence, biological relevance, and evolution, we identified and studied 1,116 IG functional proteins validating their differential expression in transcriptomic data of embryonic mouse telencephalon. Our results showed that overall expression levels of IGs are lower than those of MEGs. However, strongly up-regulated IGs include transcription factors (TFs) such as the class 3 of POU (HMG Box), Neurog1, Olig1, and BHLHe22, BHLHe23, among other essential genes including the β-cluster of protocadherins. Most striking was the finding that IG-encoded BHLH TFs fit the criteria to be classified as microproteins. Finally, predicted protein orthologs in other six genomes confirmed high conservation of IGs associated with regulating neural processes and with chromatin organization and epigenetic regulation in Vertebrata. Moreover, this study highlights that IGs are essential modulators of regulatory processes, such as the Wnt signaling pathway and biological processes as pivotal as sensory organ developing at a transcriptional and post-translational level. Overall, our results suggest that IG proteins have specialized, prevalent, and unique biological roles and that functional divergence between IGs and MEGs is likely to be the result of specific evolutionary constraints.

LRP5 and LRP6 in Wnt Signaling: Similarity and Divergence

The canonical Wnt/β-catenin signaling plays a fundamental role in regulating embryonic development, injury repair and the pathogenesis of human diseases. In vertebrates, low density lipoprotein receptor-related proteins 5 and 6 (LRP5 and LRP6), the single-pass transmembrane proteins, act as coreceptors of Wnt ligands and are indispensable for Wnt signal transduction. LRP5 and LRP6 are highly homologous and widely co-expressed in embryonic and adult tissues, and they share similar function in mediating Wnt signaling. However, they also exhibit distinct characteristics by interacting with different protein partners. As such, each of them possesses its own unique functions. In this review, we systematically discuss the similarity and divergence of LRP5 and LRP6 in mediating Wnt and other signaling in the context of kidney diseases. A better understanding of the precise role of LRP5 and LRP6 may afford us to identify and refine therapeutic targets for the treatment of a variety of human diseases.

DNA methylation and protein expression of Wnt pathway markers in progressive glioblastoma

BACKGROUND

Wnt signaling plays important roles in tumorigenesis, invasiveness and therapeutic resistance of glioblastoma (GBM).

METHODS

We simultaneously investigated six Wnt pathway markers (Wnt5a, Fzd-2, beta-catenin, Wnt3a, Wnt7b, Fzd-10) at epigenetic and protein levels in 21 sequential formalin-fixed paraffin-embedded GBM pairs and controls.

RESULTS

Expression levels of Wnt5a, beta-catenin and Wnt3a proteins either moderately or significantly increased, while those of Fzd-2, Wnt7b and Fzd-10 decreased in the primary (GBM-P) and recurrent (GBM-R) tumors compared to the controls. Methylation levels within promoters and genes showed corresponding decreases for Wnt5a, beta-catenin and Wnt3a in tumors vs. controls, while that of Fzd-10 was uniformly high. Comparing the GBM-P and GBM-R pairs, proteins of Fzd-2, beta-catenin and Wnt3a were either moderately or significantly up-, while that of Wnt7b was downregulated in GBM-R, but these patterns were not accompanied by inverse methylation patterns in the corresponding promoters and genes over time. No methylation differences were noted within promoters and genes of the same markers in 112 pairs of primary and recurrent GBMs in a database, suggesting that the observed changes in protein expression levels may not be explained by CpG methylation status alone. The promoter and gene methylation rate was the highest for Fzd-10 in the database cohort too, supporting the noted low Fzd-10 protein expression.

DISCUSSION

These analyses underscore the relevance of Wnt pathway molecules in the context of their methylation profiles in the development and evolution of GBM, and suggest that Wnt pathway regulation as a potential treatment target merits further studies.

The origin and mechanisms of smooth muscle cell development in vertebrates

Smooth muscle cells (SMCs) represent a major structural and functional component of many organs during embryonic development and adulthood. These cells are a crucial component of vertebrate structure and physiology, and an updated overview of the developmental and functional process of smooth muscle during organogenesis is desirable. Here, we describe the developmental origin of SMCs within different tissues by comparing their specification and differentiation with other organs, including the cardiovascular, respiratory and intestinal systems. We then discuss the instructive roles of smooth muscle in the development of such organs through signaling and mechanical feedback mechanisms. By understanding SMC development, we hope to advance therapeutic approaches related to tissue regeneration and other smooth muscle-related diseases.

Epigenetic regulation of Wnt7b expression by the cis-acting long noncoding RNA Lnc-Rewind in muscle stem cells

Skeletal muscle possesses an outstanding capacity to regenerate upon injury due to the adult muscle stem cell (MuSC) activity. This ability requires the proper balance between MuSC expansion and differentiation, which is critical for muscle homeostasis and contributes, if deregulated, to muscle diseases. Here, we functionally characterize a novel chromatin-associated long noncoding RNA (lncRNA), Lnc-Rewind, which is expressed in murine MuSCs and conserved in human. We find that, in mouse, Lnc-Rewind acts as an epigenetic regulator of MuSC proliferation and expansion by influencing the expression of skeletal muscle genes and several components of the WNT (Wingless-INT) signalling pathway. Among them, we identified the nearby Wnt7b gene as a direct Lnc-Rewind target. We show that Lnc-Rewind interacts with the G9a histone lysine methyltransferase and mediates the in cis repression of Wnt7b by H3K9me2 deposition. Overall, these findings provide novel insights into the epigenetic regulation of adult muscle stem cells fate by lncRNAs.

Necrotizing Enterocolitis: LPS/TLR4-Induced Crosstalk Between Canonical TGF-β/Wnt/β-Catenin Pathways and PPARγ

Necrotizing enterocolitis (NEC) represents one of the major causes of morbidity and mortality in premature infants. Several recent studies, however, have contributed to a better understanding of the pathophysiology of this dreadful disease. Numerous intracellular pathways play a key role in NEC, namely: bacterial lipopolysaccharide (LPS), LPS toll-like receptor 4 (TLR4), canonical Wnt/β-catenin signaling and PPARγ. In a large number of pathologies, canonical Wnt/β-catenin signaling and PPARγ operate in opposition to one another, so that when one of the two pathways is overexpressed the other is downregulated and vice-versa. In NEC, activation of TLR4 by LPS leads to downregulation of the canonical Wnt/β-catenin signaling and upregulation of PPARγ. This review aims to shed light on the complex intracellular mechanisms involved in this pathophysiological profile by examining additional pathways such as the GSK-3β, NF-κB, TGF-β/Smads, and PI3K-Akt pathways.

Combined Omics Approaches Reveal the Roles of Non-canonical WNT7B Signaling and YY1 in the Proliferation of Human Pancreatic Progenitor Cells

The proliferation of human pancreatic progenitor cells (PPCs) is critical for developing cell therapies for diabetes. Here, using transcriptome analysis combined with small interfering RNA (siRNA) screening, we revealed that WNT7B is a downstream growth factor of AT7867, a compound known to promote the proliferation of PPCs generated from human pluripotent stem cells. Feeder cell lines stably expressing mouse Wnt7a or Wnt7b, but not other Wnts, enhanced PPC proliferation in the absence of AT7867. Importantly, Wnt7a/b ligands did not activate the canonical Wnt pathway, and PPC proliferation depended on the non-canonical Wnt/PKC pathway. A comparison of the phosphoproteome in response to AT7867 or a newly synthesized AT7867 derivative uncovered the function of YY1 as a transcriptional regulator of WNT7B. Overall, our data highlight unknown roles of non-canonical WNT7B/PKC signaling and YY1 in human PPC proliferation and will contribute to the stable supply of a cell source for pancreatic disease modeling and therapeutic applications.

Identification of Latent Oncogenes with a Network Embedding Method and Random Forest

Oncogene is a special type of genes, which can promote the tumor initiation. Good study on oncogenes is helpful for understanding the cause of cancers. Experimental techniques in early time are quite popular in detecting oncogenes. However, their defects become more and more evident in recent years, such as high cost and long time. The newly proposed computational methods provide an alternative way to study oncogenes, which can provide useful clues for further investigations on candidate genes. Considering the limitations of some previous computational methods, such as lack of learning procedures and terming genes as individual subjects, a novel computational method was proposed in this study. The method adopted the features derived from multiple protein networks, viewing proteins in a system level. A classic machine learning algorithm, random forest, was applied on these features to capture the essential characteristic of oncogenes, thereby building the prediction model. All genes except validated oncogenes were ranked with a measurement yielded by the prediction model. Top genes were quite different from potential oncogenes discovered by previous methods, and they can be confirmed to become novel oncogenes. It was indicated that the newly identified genes can be essential supplements for previous results.

Wnt signaling and Loxl2 promote aggressive osteosarcoma

Osteosarcoma (OS) is the most frequent primary malignant bone tumor in urgent need of better therapies. Using genetically modified mouse models (GEMMs), we demonstrate that Wnt signaling promotes c-Fos-induced OS formation via the actions of the collagen-modifying enzyme Loxl2. c-Fos/AP-1 directly regulates the expression of the Wnt ligands Wnt7b and Wnt9a in OS cells through promoter binding, and Wnt7b and Wnt9a in turn promote Loxl2 expression in murine and human OS cells through the transcription factors Zeb1 and Zeb2. Concordantly, inhibition of Wnt ligand secretion by inactivating the Wnt-less (Wls) gene in osteoblasts in c-Fos GEMMs either early or in a therapeutic setting reduces Loxl2 expression and progression of OS. Wls-deficient osteosarcomas proliferate less, are less mineralized and are enriched in fibroblastic cells surrounded by collagen fibers. Importantly, Loxl2 inhibition using either the pan-Lox inhibitor BAPN or a specific inducible shRNA reduces OS cell proliferation in vitro and decreases tumor growth and lung colonization in murine and human orthotopic OS transplantation models. Finally, OS development is delayed in c-Fos GEMMs treated with BAPN or with specific Loxl2 blocking antibodies. Congruently, a strong correlation between c-FOS, LOXL2 and WNT7B/WNT9A expression is observed in human OS samples, and c-FOS/LOXL2 co-expression correlates with OS aggressiveness and decreased patient survival. Therefore, therapeutic targeting of Wnt and/or Loxl2 should be considered to potentiate the inadequate current treatments for pediatric, recurrent, and metastatic OS.

Dorsoventral inversion of the air-filled organ (lungs, gas bladder) in vertebrates: RNAsequencing of laser capture microdissected embryonic tissue

How modification of gene expression generates novel traits is key to understanding the evolutionary process. We investigated the genetic basis for the origin of the piscine gas bladder from lungs of ancestral bony vertebrates. Distinguishing these homologous organs is the direction of budding from the foregut during development; lungs bud ventrally and the gas bladder buds dorsally.

Mechanisms of the Osteogenic Switch of Smooth Muscle Cells in Vascular Calcification: WNT Signaling, BMPs, Mechanotransduction, and EndMT

Characterized by the hardening of arteries, vascular calcification is the deposition of hydroxyapatite crystals in the arterial tissue. Calcification is now understood to be a cell-regulated process involving the phenotypic transition of vascular smooth muscle cells into osteoblast-like cells. There are various pathways of initiation and mechanisms behind vascular calcification, but this literature review highlights the wingless-related integration site (WNT) pathway, along with bone morphogenic proteins (BMPs) and mechanical strain. The process mirrors that of bone formation and remodeling, as an increase in mechanical stress causes osteogenesis. Observing the similarities between the two may aid in the development of a deeper understanding of calcification. Both are thought to be regulated by the WNT signaling cascade and bone morphogenetic protein signaling and can also be activated in response to stress. In a pro-calcific environment, integrins and cadherins of vascular smooth muscle cells respond to a mechanical stimulus, activating cellular signaling pathways, ultimately resulting in gene regulation that promotes calcification of the vascular extracellular matrix (ECM). The endothelium is also thought to contribute to vascular calcification via endothelial to mesenchymal transition, creating greater cell plasticity. Each of these factors contributes to calcification, leading to increased cardiovascular mortality in patients, especially those suffering from other conditions, such as diabetes and kidney failure. Developing a better understanding of the mechanisms behind calcification may lead to the development of a potential treatment in the future.

Neonatal Wnt-dependent Lgr5 positive stem cells are essential for uterine gland development

Wnt signaling is critical for directing epithelial gland development within the uterine lining to ensure successful gestation in adults. Wnt-dependent, Lgr5-expressing stem/progenitor cells are essential for the development of glandular epithelia in the intestine and stomach, but their existence in the developing reproductive tract has not been investigated. Here, we employ Lgr5-2A-EGFP/CreERT2/DTR mouse models to identify Lgr5-expressing cells in the developing uterus and to evaluate their stem cell identity and function. Lgr5 is broadly expressed in the uterine epithelium during embryogenesis, but becomes largely restricted to the tips of developing glands after birth. In-vivo lineage tracing/ablation/organoid culture assays identify these gland-resident Lgr5^high cells as Wnt-dependent stem cells responsible for uterine gland development. Adjacent Lgr5^neg epithelial cells within the neonatal glands function as essential niche components to support the function of Lgr5^high stem cells ex-vivo. These findings constitute a major advance in our understanding of uterine development and lay the foundations for investigating potential contributions of Lgr5⁺ stem/progenitor cells to uterine disorders.

Uterine gland development is essential for successful embryo implantation, decidua formation and placental development. Here the authors demonstrate that neonatal Wnt-dependent Lgr5 expressing stem/progenitor cells at the tips of developing glands are indispensable for uterine gland development.

Endothelial YAP1 in Regenerative Lung Growth through the Angiopoietin-Tie2 Pathway

Angiogenesis, the formation of new blood capillaries, plays a key role in organ development and regeneration. Inhibition of lung angiogenesis through the blockade of angiogenic signaling pathways impairs compensatory and regenerative lung growth after unilateral pneumonectomy (PNX). The Hippo signaling transducer, Yes-associated protein (YAP) 1 binds to TEA domain transcription factor (TEAD) and controls organ size and regeneration. However, the role of endothelial YAP1 in lung vascular and alveolar morphogenesis remains unclear. In this report, we demonstrate that knockdown of YAP1 in endothelial cells (ECs) decreases angiogenic factor receptor Tie2 expression, and inhibits EC sprouting and epithelial cell budding in vitro and vascular and alveolar morphogenesis in the gel implanted on the mouse lung. The expression levels of YAP1, TEAD1, and Tie2 increase in ECs isolated from the remaining mouse lungs after unilateral PNX and vascular formation is stimulated in the post-PNX mouse lungs. Knockdown of endothelial YAP1 inhibits compensatory lung growth and vascular and alveolar morphogenesis after unilateral PNX. These findings suggest that endothelial YAP1 is required for lung vascular and alveolar regeneration and modulation of YAP1 in ECs may be novel interventions for the improvement of lung regeneration.

Airway epithelial cell isolation techniques affect DNA methylation profiles with consequences for analysis of asthma related perturbations to DNA methylation

The airway epithelium forms the interface between the inhaled environment and the lung. The airway epithelium is dysfunctional in asthma and epigenetic mechanisms are considered a contributory factor. We hypothesised that the DNA methylation profiles of cultured primary airway epithelial cells (AECs) would differ between cells isolated from individuals with asthma (n = 17) versus those without asthma (n = 16). AECs were isolated from patients by two different isolation techniques; pronase digestion (9 non-asthmatic, 8 asthmatic) and bronchial brushings (7 non-asthmatic and 9 asthmatic). DNA methylation was assessed using an Illumina Infinium HumanMethylation450 BeadChip array. DNA methylation of AECs clustered by isolation technique and linear regression identified 111 CpG sites differentially methylated between isolation techniques in healthy individuals. As a consequence, the effect of asthmatic status on DNA methylation was assessed within AEC samples isolated using the same technique. In pronase isolated AECs, 15 DNA regions were differentially methylated between asthmatics and non-asthmatics. In bronchial brush isolated AECs, 849 differentially methylated DNA regions were identified with no overlap to pronase regions. In conclusion, regardless of cell isolation technique, differential DNA methylation was associated with asthmatic status in AECs, providing further evidence for aberrant DNA methylation as a signature of epithelial dysfunction in asthma.

Smooth Muscle Differentiation of Penile Stem/Progenitor Cells Induced by Microenergy Acoustic Pulses In Vitro

INTRODUCTION

Modulating tissue-resident stem and progenitor cells with a non-invasive, mechanobiological intervention is an optimal approach for tissue regeneration. Stem cell antigen-1 (Sca-1) has been identified as a stem cell marker within many organs but never within the penis.

AIM

To localize and isolate penile stem/progenitor cells (PSPCs) and to evaluate cellular differentiation after exposure to induction medium and microenergy acoustic pulse (MAP) therapy.

METHODS

Six male Sprague-Dawley rats were used to isolate PSPCs. Isolation was followed by stem cell characterization and differentiation assays. The PSPCs were then treated with MAP (0.033 mJ/mm², 1 Hz) at various dosages (25, 50, 100, and 200 pulses) and for different durations (1, 2, 4, 6, or 8 hours) in vitro.

MAIN OUTCOME MEASURE

The PSPCs (Sca-1-positive cells) were isolated using the magnetic-activated cell sorting system. PSPC cellular differentiation was assessed after induction with induction medium and with MAP in vitro. Wnt/β-catenin signaling was also assayed.

RESULTS

The PSPCs were successfully localized within the penile subtunic and perisinusoidal spaces, and they were successfully isolated using magnetic-activated cell sorting. The stemness of the cells was confirmed by stem cell marker characterization and by multiple differentiation into smooth muscle cells, endothelial cells, adipocytes, and neurons. MAP-induced PSPCs differentiated into smooth muscle cells by activating the Wnt/β-catenin signaling pathway in a time- and dosage-dependent manner.

CLINICAL IMPLICATIONS

By modulating resident PSPCs, MAP may have utility in the treatment of erectile dysfunction (ED).

STRENGTHS & LIMITATIONS

This study provides solid evidence in support of microenergy therapies, including both MAP and low-intensity extracorporeal shock wave therapy, for the treatment of ED. Additional studies are needed and should include additional stem cells markers. Furthermore, studies exploring the underling mechanisms for PSPC activation and differentiation are required.

CONCLUSION

PSPCs were successfully identified, localized, and isolated. Additionally, MAP provoked PSPCs to differentiate into smooth muscle cells via the Wnt/β-catenin signaling pathway. As such, MAP provides a novel method for activating endogenous tissue-resident stem/progenitor cells and might facilitate stem cell regenerative therapy targeting ED. Peng D, Yuan H, Liu T, et al. Smooth Muscle Differentiation of Penile Stem/Progenitor Cells Induced by Microenergy Acoustic Pulses In Vitro. J Sex Med 2019; 16:1874-1884.

The role of Wnt7B in the mediation of dentinogenesis via the ERK1/2 pathway

OBJECTIVES

This study investigates the role of Wnt7b in mouse dentin formation.

DESIGN

C57BL/6 mouse tooth germs at different developmental stages were collected to measure the expression of Wnt7b by immunohistochemical staining. The morphology of mandibles of Dmp1-cre;ROSA26-Wnt7b transgenic mice and ROSA26-Wnt7b littermates was analyzed by Micro-CT and HE staining. The ultramicrostructure of dentin was scanned with an electron microscope. Primary mouse dental papillae cells (MDPCs) and odontoblastic cell line (A11) were cultured and infected with adenovirus to overexpress Wnt7b. Cell proliferation and cell apoptosis were evaluated using CCK-8 and flow cytometry. Osteogenic differentiation of MDPCs and A11 was assessed by Alizarin red staining, and qPCR detection of osteogenic gene expression. The activation of signaling pathways was measured by the use of western blot analysis. The ERK1/2 inhibitor was used to test the effect of Wnt7b regulated cell differentiation.

RESULTS

Wnt7b was expressed principally in the mouse odontoblast layer after the early bell stage. In transgenic mice, Wnt7b was over-expressed in tooth mesenchyme, with a thinner predentin layer and thicker intertubular dentin. Both the micro-hardness value and the Ca/Pi ratio of dentin of transgenic mice were higher. Wnt7b promoted proliferation and mineralization of MDPCs and A11. The protein level of p-ERK1/2 was found to be higher in A11 infected with Ad-Wnt7b. The ERK signaling pathway inhibitor partly rescued the Wnt7b-induced differentiation of A11.

CONCLUSIONS

Wnt7b enhances dentinogenesis by increasing the proliferation and differentiation of dental mesenchymal cells partly through ERK1/2 pathway.

Integrin α9 depletion promotes β-catenin degradation to suppress triple-negative breast cancer tumor growth and metastasis

Although integrin α9 (ITGA9) is known to be involved in cell adhesion and motility, its expression in cancer and its role in tumor growth and metastasis remain largely unknown. Our study was designed to investigate the role of ITGA9 in triple-negative breast cancer (TNBC). ITGA9 expression in TNBC cells was knocked out (KO) using CRISPR/Cas9 technology. Four orthotopic mouse mammary xenograft tumor models coupled with cell culture studies were performed to determine the effect of ITGA9 depletion on TNBC tumor growth and metastasis and the underlying mechanism. Bioinformatics analysis showed that ITGA9 level is significantly higher in TNBC than other breast cancer subtypes, and higher ITGA9 level is associated with significantly worse distant metastasis-free survival and recurrence-free survival in TNBC patients. Experimentally, ITGA9 KO significantly reduced TNBC cell cancer stem cell (CSC)-like property, tumor angiogenesis, tumor growth and metastasis by promoting β-catenin degradation. Further mechanistic studies revealed that ITGA9 KO causes integrin-linked kinase (ILK) relocation from the membrane region to the cytoplasm, where it interacts with protein kinase A (PKA) and inhibits PKA activity leading to increased activity of glycogen synthase kinase 3 (GSK3) and subsequent β-catenin degradation. Overexpressing β-catenin in ITGA9 KO cells reversed the inhibitory effect of ITGA9 KO on tumor growth and metastasis. Furthermore, ITGA9 downregulation in TNBC tumors by nanoparticle-mediated delivery of ITGA9 siRNA drastically decreased tumor angiogenesis, tumor growth and metastasis. These findings indicate that ITGA9 depletion suppresses TNBC tumor growth and metastasis by promoting β-catenin degradation through the ILK/PKA/GSK3 pathway.

LRP5 in age-related changes in vascular and alveolar morphogenesis in the lung

Aging is associated with impaired angiogenesis and lung alveolar regeneration, which contributes to the increased susceptibility to chronic lung diseases (CLD). We have reported that the Wnt ligand co-receptor, low-density lipoprotein receptor-related protein 5 (LRP5), stimulates angiogenesis and lung alveolar regeneration. However, the role of LRP5 in age-related decline in vascular and alveolar morphogenesis remains unclear. In this report, we have demonstrated that vascular and alveolar structures are disrupted in the 24-month (24M) old mouse lungs. The expression of LRP5 and the major angiogenic factors, VEGFR2 and Tie2, is lower in endothelial cells (ECs) isolated from 24M old mouse lungs compared to those from 2M old mouse lungs. Vascular and alveolar formation is attenuated in the hydrogel implanted on the 24M old mouse lungs, while overexpression of LRP5, which restores angiogenic factor expression, reverses vascular and alveolar morphogenesis in the gel. Compensatory lung growth after unilateral pneumonectomy is inhibited in 24M old mice, which is reversed by overexpression of LRP5. These results suggest that LRP5 mediates age-related inhibition of angiogenesis and alveolar morphogenesis. Modulation of LRP5 may be a novel intervention to rejuvenate regenerative ability in aged lung and will lead to the development of efficient strategies for aging-associated CLD.

Long noncoding RNA OIP5-AS1 targets Wnt-7b to affect glioma progression via modulation of miR-410

The present study was undertaken to investigate the underlying mechanisms of long noncoding RNA OIP5-AS1 via regulating miR-410 to modulate Wnt-7b in the progression of glioma. To address this problem, we measured the expression of OIP5-AS1 and miR-410 in glioma tissues by qRT-PCR. Glioma U87 cells were transfected with OIP5-AS1 siRNA or miR-410 inhibitors. The targeting relationships among miR-410, OIP5-AS1 and Wnt-7b were verified by luciferase reporter assays. Western blotting was employed to determine the expression of Wnt-7b/β-catenin pathway-related proteins, while MTT, flow cytometry, Transwell assays and wound-healing assays were used to measure the biological characteristics of glioma cells. The results showed that OIP5-AS1 expression was higher and miR-410 was lower in glioma tissues. Luciferase reporter assays confirmed a targeting relationship between OIP5-AS1 and miR-410, as well as between miR-410 and Wnt-7b. Silencing OIP5-AS1 reduced cell proliferation, invasion and migration of glioma U87 cells and led to depressed expression levels of miR-410, Wnt-7b, p-β-catenin, GSK-3β-pS9, c-Myc and cyclin D1. Furthermore, down-regulation of OIP5-AS1 induced G0/G1 phase cell cycle arrest and apoptosis of glioma cells. Inhibitors of miR-410 abolished the biological effects of OIP5-AS1 siRNA in glioma cells. In vivo, OIP5-AS1 knockdown also inhibited tumor growth. Taken together, this research suggested that silencing OIP5-AS1 may specifically block the Wnt-7b/β-catenin pathway via targeted up-regulating miR-410, thereby inhibiting growth, invasion and migration while promoting apoptosis in glioma cells.

Transcriptome Analysis of Infected and Bystander Type 2 Alveolar Epithelial Cells during Influenza A Virus Infection Reveals In Vivo Wnt Pathway Downregulation

Influenza virus outbreaks remain a serious threat to public health. A greater understanding of how cells targeted by the virus respond to the infection can provide insight into the pathogenesis of disease. Here we examined the transcriptional profile of in vivo-infected and uninfected type 2 alveolar epithelial cells (AEC) in the lungs of influenza virus-infected mice. We show for the first time the unique gene expression profiles induced by the in vivo infection of AEC as well as the transcriptional response of uninfected bystander cells. This work allows us to distinguish the direct and indirect effects of infection at the cellular level. Transcriptome analysis revealed that although directly infected and bystander AEC from infected animals shared many transcriptome changes compared to AEC from uninfected animals, directly infected cells produce more interferon and express lower levels of Wnt signaling-associated transcripts, while concurrently expressing more transcripts associated with cell death pathways, than bystander uninfected AEC. The Wnt signaling pathway was downregulated in both in vivo-infected AEC and in vitro-infected human lung epithelial A549 cells. Wnt signaling did not affect type I and III interferon production by infected A549 cells. Our results reveal unique transcriptional changes that occur within infected AEC and show that influenza virus downregulates Wnt signaling. In light of recent findings that Wnt signaling is essential for lung epithelial stem cells, our findings reveal a mechanism by which influenza virus may affect host lung repair.IMPORTANCE Influenza virus infection remains a major public health problem. Utilizing a recombinant green fluorescent protein-expressing influenza virus, we compared the in vivo transcriptomes of directly infected and uninfected bystander cells from infected mouse lungs and discovered many pathways uniquely regulated in each population. The Wnt signaling pathway was downregulated in directly infected cells and was shown to affect virus but not interferon production. Our study is the first to discern the in vivo transcriptome changes induced by direct viral infection compared to mere exposure to the lung inflammatory milieu and highlight the downregulation of Wnt signaling. This downregulation has important implications for understanding influenza virus pathogenesis, as Wnt signaling is critical for lung epithelial stem cells and lung epithelial cell differentiation. Our findings reveal a mechanism by which influenza virus may affect host lung repair and suggest interventions that prevent damage or accelerate recovery of the lung.

Transcriptional regulation of cell shape during organ morphogenesis

The emerging field of transcriptional regulation of cell shape changes aims to address the critical question of how gene expression programs produce a change in cell shape. Together with cell growth, division, and death, changes in cell shape are essential for organ morphogenesis. Whereas most studies of cell shape focus on posttranslational events involved in protein organization and distribution, cell shape changes can be genetically programmed. This review highlights the essential role of transcriptional regulation of cell shape during morphogenesis of the heart, lungs, gastrointestinal tract, and kidneys. We emphasize the evolutionary conservation of these processes across different model organisms and discuss perspectives on open questions and research avenues that may provide mechanistic insights toward understanding birth defects.

Integrin α5 down-regulation by miR-205 suppresses triple negative breast cancer stemness and metastasis by inhibiting the Src/Vav2/Rac1 pathway

Triple negative breast cancer (TNBC) usually displays more aggressive metastasis, the underlying mechanism is unclear. Previous studies showed that microRNA-205 (miR-205) has controversial roles in cancer, however, its role in TNBC metastasis and the underlying mechanism have not been well-understood. In this study we found that miR-205 expression level is extremely low in basal mesenchymal-like highly migratory and invasive TNBC cells. Stably re-expressing miR-205 in TNBC cells significantly reduced their migration, invasion capability and cancer stem cell (CSC)-like property. Nude mouse orthotopic mammary xenograft tumor model study revealed that miR-205 re-expression greatly decreases TNBC tumor growth and abolishes spontaneous lung metastasis. Mechanistic studies demonstrated that miR-205 inhibits TNBC cell metastatic traits and tumor metastasis by down-regulating integrin α5 (ITGA5). Moreover, ITGA5 knockout using the CRISPR/Cas9 technique achieved the same strong inhibitory effect on TNBC cell CSC-like property and tumor metastasis as re-expressing miR-205 did. Further mechanistic studies indicated that ITGA5 down-regulation by miR-205 re-expression impairs TNBC cell metastatic traits by inhibiting the Src/Vav2/Rac1 pathway. Together, our findings suggest that miR-205 and ITGA5 may serve as potential targets for developing effective therapies for metastatic TNBC.

Development of the renal vasculature

The kidney vasculature has a unique and complex architecture that is central for the kidney to exert its multiple and essential physiological functions with the ultimate goal of maintaining homeostasis. An appropriate development and coordinated assembly of the different vascular cell types and their association with the corresponding nephrons is crucial for the generation of a functioning kidney. In this review we provide an overview of the renal vascular anatomy, histology, and current knowledge of the embryological origin and molecular pathways involved in its development. Understanding the cellular and molecular mechanisms involved in renal vascular development is the first step to advance the field of regenerative medicine.

Glucocorticoids, genes and brain function

The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.

Inhibition of canonical WNT/β-catenin signaling is involved in leflunomide (LEF)-mediated cytotoxic effects on renal carcinoma cells

Leflunomide (LEF), an inhibitor of dihydroorotate dehydrogenase (DHODH) in pyrimidine biosynthetic pathway, is an immunomodulatory agent approved for the treatment of rheumatoid arthritis. In this study, we show that LEF significantly reduced cell proliferation of renal carcinoma cells in a concentration-dependent manner. LEF at 50 μM induced S-phase arrest and autophagy. Higher doses of LEF (>50 μM) effectively induced cell apoptosis. Modulating the concentration of LEF resulted in distinct effects on the expression of regulatory proteins associated with cell cycle, apoptosis, and autophagy. In particular, high concentrations of LEF inhibited canonical WNT signaling by promoting nucleo-cytoplasmic shuttling and proteasome-dependent degradation of β-catenin. Mechanistic studies showed that the repression of AKT activation partly accounted for LEF-mediated WNT inhibition. Gene expression microarray revealed that LEF treatment greatly inhibited the expression of FZD10 gene, a receptor mediating WNT/β-catenin activation. In vivo xenograft study in NOD/SCID mice further validated the inhibitory effects of LEF on tumor growth and Wnt/β-catenin signaling. However, LEF treatment also triggered cell autophagy and elevated the expression of WNT3a, which ameliorated its cytotoxic effects. The combination of LEF with a WNT inhibitor IWP-2 or autophagy inhibitor HCQ could yield an enhanced anti-tumor outcome. Taken together, these results identify the potential utility and pharmacological feature of LEF in the chemotherapy of renal cell carcinoma (RCC).

WNT receptor signalling in lung physiology and pathology

The WNT signalling cascades have emerged as critical regulators of a wide variety of biological aspects involved in lung development as well as in physiological and pathophysiological processes in the adult lung. WNTs (secreted glycoproteins) interact with various transmembrane receptors and co-receptors to activate signalling pathways that regulate transcriptional as well as non-transcriptional responses within cells. In physiological conditions, the majority of WNT receptors and co-receptors can be detected in the adult lung. However, dysregulation of WNT signalling pathways contributes to the development and progression of chronic lung pathologies, including idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), asthma and lung cancer. The interaction between a WNT and the (co-)receptor(s) present at the cell surface is the initial step in transducing an extracellular signal into an intracellular response. This proximal event in WNT signal transduction with (cell-specific) ligand-receptor interactions is of great interest as a potential target for pharmacological intervention. In this review we highlight the diverse expression of various WNT receptors and co-receptors in the aforementioned chronic lung diseases and discuss the currently available biologicals and pharmacological tools to modify proximal WNT signalling.

Notum attenuates Wnt/β-catenin signaling to promote tracheal cartilage patterning

Tracheobronchomalacia (TBM) is a common congenital disorder in which the cartilaginous rings of the trachea are weakened or missing. Despite the high prevalence and clinical issues associated with TBM, the etiology is largely unknown. Our previous studies demonstrated that Wntless (Wls) and its associated Wnt pathways are critical for patterning of the upper airways. Deletion of Wls in respiratory endoderm caused TBM and ectopic trachealis muscle. To understand mechanisms by which Wls mediates tracheal patterning, we performed RNA sequencing in prechondrogenic tracheal tissue of Wls^f/f;Shh^Cre/wt embryos. Chondrogenic Bmp4, and Sox9 were decreased, while expression of myogenic genes was increased. We identified Notum, a deacylase that inactivates Wnt ligands, as a target of Wls induced Wnt signaling. Notum's mesenchymal ventral expression in prechondrogenic trachea overlaps with expression of Axin2, a Wnt/β-catenin target and inhibitor. Notum is induced by Wnt/β-catenin in developing trachea. Deletion of Notum activated mesenchymal Wnt/β-catenin and caused tracheal mispatterning of trachealis muscle and cartilage as well as tracheal stenosis. Notum is required for tracheal morphogenesis, influencing mesenchymal condensations critical for patterning of tracheal cartilage and muscle. We propose that Notum influences mesenchymal cell differentiation by generating a barrier for Wnt ligands produced and secreted by airway epithelial cells to attenuate Wnt signaling.

The WNT7B protein promotes the migration and differentiation of human dental pulp cells partly through WNT/beta-catenin and c-Jun N-terminal kinase signalling pathways

OBJECTIVE

The aim of this study is to investigate the role of the WNT7B protein in the migration and differentiation of human dental pulp cells (HDPCs).

DESIGN

The effect of recombinant human WNT7B (rhWNT7B) on the proliferation and migration of HDPCs was evaluated by 5-ethynyl-2'-deoxyuridine (EdU), immunofluorescence staining of Ki67, flow cytometry and scratch assay; the differentiation of HDPCs was measured by alkaline phosphatase (ALP) staining, alizarin red staining, ALP activity, qPCR and western blot. The activation of the WNT/beta-catenin (WNT/β-catenin) and c-Jun N-terminal kinase (JNK) pathways was analysed by western blot, immunocytochemistry and dual luciferase assays. XAV939 and SP600125，the inhibitors of the WNT/β-catenin and JNK pathways, were further applied to verify the mechanism.

RESULTS

rhWNT7B repressed the proliferation but did not affect the apoptosis of HDPCs. In the presence of rhWNT7B, ALP and alizarin red staining were increased substantially in the HDPCs with osteogenic induction; the gene expression of Runx2 and Col1 in HDPCs was quite elevated compared with that induced in osteogenic medium without WNT7B measured by qPCR; The ALP activity was also increased with rhWNT7B stimulation in HDPCs after 7-day odontogenic culture; Western blot revealed that the expression of dentin sialophosphoprotein (DSPP) of HDPCs was up-regulated significantly with the addition of WNT7B as well. Further study showed that rhWNT7B activated the WNT/β-catenin and JNK signalling pathways in the differentiation of HDPCs. XAV939 and SP600125 can partly offset the effect of the WNT7B-induced differentiation of HDPCs.

CONCLUSION

WNT7B promoted the differentiation of HDPCs partly through the WNT/β-catenin and JNK signalling pathways.

Wnt/β-catenin signaling links embryonic lung development and asthmatic airway remodeling

Embryonic lung development requires reciprocal endodermal-mesodermal interactions; mediated by various signaling proteins. Wnt/β-catenin is a signaling protein that exhibits the pivotal role in lung development, injury and repair while aberrant expression of Wnt/β-catenin signaling leads to asthmatic airway remodeling: characterized by hyperplasia and hypertrophy of airway smooth muscle cells, alveolar and vascular damage goblet cells metaplasia, and deposition of extracellular matrix; resulting in decreased lung compliance and increased airway resistance. The substantial evidence suggests that Wnt/β-catenin signaling links embryonic lung development and asthmatic airway remodeling. Here, we summarized the recent advances related to the mechanistic role of Wnt/β-catenin signaling in lung development, consequences of aberrant expression or deletion of Wnt/β-catenin signaling in expansion and progression of asthmatic airway remodeling, and linking early-impaired pulmonary development and airway remodeling later in life. Finally, we emphasized all possible recent potential therapeutic significance and future prospectives, that are adaptable for therapeutic intervention to treat asthmatic airway remodeling.

Roles of Wnt Target Genes in the Journey of Cancer Stem Cells

The importance of Wnt/β-catenin signaling in cancer stem cells (CSCs) has been acknowledged; however, the mechanism through which it regulates the biological function of CSCs and promotes cancer progression remains elusive. Hence, to understand the intricate mechanism by which Wnt controls stemness, the specific downstream target genes of Wnt were established by analyzing the genetic signatures of multiple types of metastatic cancers based on gene set enrichment. By focusing on the molecular function of Wnt target genes, the biological roles of Wnt were interpreted in terms of CSC dynamics from initiation to metastasis. Wnt signaling participates in cancer initiation by generating CSCs from normal stem cells or non-CSCs and augmenting persistent growth at the primary region, which is resistant to anti-cancer therapy. Moreover, it assists CSCs in invading nearby tissues and in entering the blood stream, during which the negative feedback of the Wnt signaling pathway maintains CSCs in a dormant state that is suitable for survival. When CSCs arrive at distant organs, another burst of Wnt signaling induces CSCs to succeed in re-initiation and colonization. This comprehensive understanding of Wnt target genes provides a plausible explanation for how Wnt allows CSCs variation during cancer progression.

Structure-based prediction of Wnt binding affinities for Frizzled-type cysteine-rich domains

Wnt signaling pathways are of significant interest in development and oncogenesis. The first step in these pathways typically involves the binding of a Wnt protein to the cysteine-rich domain (CRD) of a Frizzled receptor. Wnt-Frizzled interactions can be antagonized by secreted Frizzled-related proteins (SFRPs), which also contain a Frizzled-like CRD. The large number of Wnts, Frizzleds, and SFRPs, as well as the hydrophobic nature of Wnt, poses challenges to laboratory-based investigations of interactions involving Wnt. Here, utilizing structural knowledge of a representative Wnt-Frizzled CRD interaction, as well as experimentally determined binding affinities for a selection of Wnt-Frizzled CRD interactions, we generated homology models of Wnt-Frizzled CRD interactions and developed a quantitative structure-activity relationship for predicting their binding affinities. The derived model incorporates a small selection of terms derived from scoring functions used in protein-protein docking, as well as an energetic term considering the contribution made by the lipid of Wnt to the Wnt-Frizzled binding affinity. Validation with an external test set suggests that the model can accurately predict binding affinity for 75% of cases and that the error associated with the predictions is comparable with the experimental error. The model was applied to predict the binding affinities of the full range of mouse and human Wnt-Frizzled and Wnt-SFRP interactions, indicating trends in Wnt binding affinity for Frizzled and SFRP CRDs. The comprehensive predictions made in this study provide the basis for laboratory-based studies of previously unexplored Wnt-Frizzled and Wnt-SFRP interactions, which, in turn, may reveal further Wnt signaling pathways.

FZD10-Gα13 signalling axis points to a role of FZD10 in CNS angiogenesis

Among the 10 Frizzled (FZD) isoforms belonging to the Class F of G protein-coupled receptors (GPCRs), FZD₁₀ remains the most enigmatic. FZD₁₀ shows homology to FZD₄ and FZD₉ and was previously implicated in both β-catenin-dependent and -independent signalling. In normal tissue, FZD₁₀ levels are generally very low; however, its upregulation in synovial carcinoma has attracted some attention for therapy. Our findings identify FZD₁₀ as a receptor interacting with and signalling through the heterotrimeric G protein Gα₁₃ but not Gα_12, Gα_i1, Gα_oA, Gα_s, or Gα_q. Stimulation with the FZD agonist WNT induced the dissociation of the Gα₁₃ protein from FZD₁₀, and led to global Gα_12/13-dependent cell changes assessed by dynamic mass redistribution measurements. Furthermore, we show that FZD₁₀ mediates Gα_12/13 activation-dependent induction of YAP/TAZ transcriptional activity. In addition, we show a distinct expression of FZD₁₀ in embryonic CNS endothelial cells at E11.5-E14.5. Given the well-known importance of Gα₁₃ signalling for the development of the vascular system, the selective expression of FZD₁₀ in brain vascular endothelial cells points at a potential role of FZD₁₀-Gα₁₃ signalling in CNS angiogenesis.

Linking bronchopulmonary dysplasia to adult chronic lung diseases: role of WNT signaling

Bronchopulmonary dysplasia (BPD) is one of the most common chronic lung diseases in infants caused by pre- and/or postnatal lung injury. BPD is characterized by arrested alveolarization and vascularization due to extracellular matrix remodeling, inflammation, and impaired growth factor signaling. WNT signaling is a critical pathway for normal lung development, and its altered signaling has been shown to be involved in the onset and progression of incurable chronic lung diseases in adulthood, such as chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF). In this review, we summarize the impact of WNT signaling on different stages of lung development and its potential contribution to developmental lung diseases, especially BPD, and chronic lung diseases in adulthood.

Tbx2 and Tbx3 Act Downstream of Shh to Maintain Canonical Wnt Signaling during Branching Morphogenesis of the Murine Lung

Numerous signals drive the proliferative expansion of the distal endoderm and the underlying mesenchyme during lung branching morphogenesis, but little is known about how these signals are integrated. Here, we show by analysis of conditional double mutants that the two T-box transcription factor genes Tbx2 and Tbx3 act together in the lung mesenchyme to maintain branching morphogenesis. Expression of both genes depends on epithelially derived Shh signaling, with additional modulation by Bmp, Wnt, and Tgfβ signaling. Genetic rescue experiments reveal that Tbx2 and Tbx3 function downstream of Shh to maintain pro-proliferative mesenchymal Wnt signaling, in part by direct repression of the Wnt antagonists Frzb and Shisa3. In combination with our previous finding that Tbx2 and Tbx3 repress the cell-cycle inhibitors Cdkn1a and Cdkn1b, we conclude that Tbx2 and Tbx3 maintain proliferation of the lung mesenchyme by way of at least two molecular mechanisms: regulating cell-cycle regulation and integrating the activity of multiple signaling pathways.