Search Results (22)

In neurons, the acquisition of a polarized morphology is achieved upon the outgrowth of a single axon from one of several neurites. Small extracellular vesicles (sEVs), such as exosomes, from diverse sources are known to promote neurite outgrowth and thus may have therapeutic potential. However, the effect of fibroblast-derived exosomes on axon elongation in neurons of the central nervous system under growth-permissive conditions remains unclear. Here, we show that fibroblast-derived sEVs promote axon outgrowth and a polarized neuronal morphology in mouse primary embryonic cortical neurons. Mechanistically, we demonstrate that the sEV-induced increase in axon outgrowth requires endogenous Wnts and core PCP components including Prickle, Vangl, Frizzled, and Dishevelled. We demonstrate that sEVs are internalized by neurons, colocalize with Wnt7b, and induce relocalization of Vangl2 to the distal axon during axon outgrowth. In contrast, sEVs derived from neurons or astrocytes do not promote axon outgrowth, while sEVs from activated astrocytes inhibit elongation. Thus, our data reveal that fibroblast-derived sEVs promote axon elongation through the Wnt-PCP pathway in a manner that is dependent on endogenous Wnts. Full article

The formation of the embryonic left–right axis is a fundamental process in animals, which subsequently conditions both the shape and the correct positioning of internal organs. During vertebrate early development, a transient structure, known as the left–right organizer, breaks the bilateral symmetry in a manner that is critically dependent on the activity of motile and immotile cilia or asymmetric cell migration. Extensive studies have partially elucidated the molecular pathways that initiate left–right asymmetric patterning and morphogenesis. Wnt/planar cell polarity signaling plays an important role in the biased orientation and rotational motion of motile cilia. The leftward fluid flow generated in the cavity of the left–right organizer is sensed by immotile cilia through complex mechanisms to trigger left-sided calcium signaling and lateralized gene expression pattern. Disrupted asymmetric positioning or impaired structure and function of cilia leads to randomized left–right axis determination, which is closely linked to laterality defects, particularly congenital heart disease. Despite of the formidable progress made in deciphering the critical contribution of cilia to establishing the left–right asymmetry, a strong challenge remains to understand how cilia generate and sense fluid flow to differentially activate gene expression across the left–right axis. This review analyzes mechanisms underlying the asymmetric morphogenesis and function of the left–right organizer in left–right axis formation. It also aims to identify important questions that are open for future investigations. Full article

The TaqIA polymorphism is a marker of both the Ankyrin Repeat and Kinase Domain containing I gene (ANKK1) encoding a RIP-kinase, and the DRD2 gene for the dopamine receptor D2. Despite a large number of studies of TaqIA in addictions and other psychiatric disorders, there is difficulty in interpreting this genetic phenomenon due to the lack of knowledge about ANKK1 function. In SH-SY5Y neuroblastoma models, we show that ANKK1 interacts with the synapse protein FERM ARH/RhoGEF and Pleckstrin Domain 1 (FARP1), which is a guanine nucleotide exchange factor (GEF) of the RhoGTPases RAC1 and RhoA. ANKK1–FARP1 colocalized in F-ACTIN-rich structures for neuronal maturation and migration, and both proteins activate the Wnt/PCP pathway. ANKK1, but not FARP1, promotes neuritogenesis, and both proteins are involved in neuritic spine outgrowth. Notably, the knockdown of ANKK1 or FARP1 affects RhoGTPases expression and neural differentiation. Additionally, ANKK1 binds WGEF, another GEF of Wnt/PCP, regulating its interaction with RhoA. During neuronal differentiation, ANKK1–WGEF interaction is downregulated, while ANKK1–FARP1 interaction is increased, suggesting that ANKK1 recruits Wnt/PCP components for bidirectional control of F-ACTIN assembly. Our results suggest a brain structural basis in TaqIA-associated phenotypes. Full article

The establishment of neuronal polarity, involving axon specification and outgrowth, is critical to achieve the proper morphology of neurons, which is important for neuronal connectivity and cognitive functions. Extracellular factors, such as Wnts, modulate diverse aspects of neuronal morphology. In particular, non-canonical Wnt5a exhibits differential effects on neurite outgrowth depending upon the context. Thus, the role of Wnt5a in axon outgrowth and neuronal polarization is not completely understood. In this study, we demonstrate that Wnt5a, but not Wnt3a, promotes axon outgrowth in dissociated mouse embryonic cortical neurons and does so in coordination with the core PCP components, Prickle and Vangl. Unexpectedly, exogenous Wnt5a-induced axon outgrowth was dependent on endogenous, neuronal Wnts, as the chemical inhibition of Porcupine using the IWP2- and siRNA-mediated knockdown of either Porcupine or Wntless inhibited Wnt5a-induced elongation. Importantly, delayed treatment with IWP2 did not block Wnt5a-induced elongation, suggesting that endogenous Wnts and Wnt5a act during specific timeframes of neuronal polarization. Wnt5a in fibroblast-conditioned media can associate with small extracellular vesicles (sEVs), and we also show that these Wnt5a-containing sEVs are primarily responsible for inducing axon elongation. Full article

The planar cell polarity (PCP) system is essential for positioning cells in 3D networks to establish the proper morphogenesis, structure, and function of organs during embryonic development. The PCP system uses inter- and intracellular feedback interactions between components of the core PCP, characterized by coordinated planar polarization and asymmetric distribution of cell populations inside the cells. PCP signaling connects the anterior–posterior to left–right embryonic plane polarity through the polarization of cilia in the Kupffer’s vesicle/node in vertebrates. Experimental investigations on various genetic ablation-based models demonstrated the functions of PCP in planar polarization and associated genetic disorders. This review paper aims to provide a comprehensive overview of PCP signaling history, core components of the PCP signaling pathway, molecular mechanisms underlying PCP signaling, interactions with other signaling pathways, and the role of PCP in organ and embryonic development. Moreover, we will delve into the negative feedback regulation of PCP to maintain polarity, human genetic disorders associated with PCP defects, as well as challenges associated with PCP. Full article

Adequate nutrient supply is crucial for the proper development of the embryo. Although nutrient supply is determined by maternal diet, the gut microbiota also influences nutrient availability. While currently there is no cure for neural tube defects (NTDs), their prevention is largely amenable to maternal folic acid and inositol supplementation. The gut microbiota also contributes to the production of these nutrients, which are absorbed by the host, but its role in this context remains largely unexplored. In this study, we performed a functional and morphological analysis of the intestinal tract of loop-tail mice (Vangl2 mutants), a mouse model of folate/inositol-resistant NTDs. In addition, we investigated the changes in gut microbiota using 16S rRNA gene sequencing regarding (1) the host genotype; (2) the sample source for metagenomics analysis; (3) the pregnancy status in the gestational window of neural tube closure; (4) folic acid and (5) D-chiro-inositol supplementation. We observed that Vangl2^+/Lp mice showed no apparent changes in gastrointestinal transit time or fecal output, yet exhibited increased intestinal length and cecal weight and gut dysbiosis. Moreover, our results showed that the mice supplemented with folic acid and D-chiro-inositol had significant changes in their microbiota composition, which are changes that could have implications for nutrient absorption. Full article

Wnt/β-catenin (WβC) signaling pathway is an important signaling pathway for the maintenance of cellular homeostasis from the embryonic developmental stages to adulthood. The canonical pathway of WβC signaling is essential for neurogenesis, cell proliferation, and neurogenesis, whereas the noncanonical pathway (WNT/Ca²⁺ and WNT/PCP) is responsible for cell polarity, calcium maintenance, and cell migration. Abnormal regulation of WβC signaling is involved in the pathogenesis of several neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and spinal muscular atrophy (SMA). Hence, the alteration of WβC signaling is considered a potential therapeutic target for the treatment of neurodegenerative disease. In the present review, we have used the bibliographical information from PubMed, Google Scholar, and Scopus to address the current prospects of WβC signaling role in the abovementioned neurodegenerative diseases. Full article

Colorectal cancer (CRC) represents one of the most common cancers worldwide, with a high mortality rate despite the decreasing incidence and new diagnostic and therapeutic strategies. CRC arises from both epidemiologic and molecular backgrounds. In addition to hereditary factor and genetic mutations, the strongly varying incidence of CRC is closely linked to chronic inflammatory disorders of the intestine and terrible dietary habits. The Wnt signalling pathway is a complex regulatory network that is implicated in many CRC physiological processes, including cancer occurrence, development, prognosis, invasion, and metastasis. It is currently believed to include classical Wnt/β-catenin, Wnt/PCP, and Wnt/Ca²⁺. In this review, we summarise the recent mechanisms and potential regulators of the three branches of the Wnt signalling pathway in CRC. Full article

Wnt signaling has been shown to play multiple roles in regenerative processes, one of the most widely studied of which is the regeneration of the intestinal luminal epithelia. Most studies in this area have focused on self-renewal of the luminal stem cells; however, Wnt signaling may also have more dynamic functions, such as facilitating intestinal organogenesis. To explore this possibility, we employed the sea cucumber Holothuria glaberrima that can regenerate a full intestine over the course of 21 days after evisceration. We collected RNA-seq data from various intestinal tissues and regeneration stages and used these data to define the Wnt genes present in H. glaberrima and the differential gene expression (DGE) patterns during the regenerative process. Twelve Wnt genes were found, and their presence was confirmed in the draft genome of H. glaberrima. The expressions of additional Wnt-associated genes, such as Frizzled and Disheveled, as well as genes from the Wnt/β-catenin and Wnt/Planar Cell Polarity (PCP) pathways, were also analyzed. DGE showed unique distributions of Wnt in early- and late-stage intestinal regenerates, consistent with the Wnt/β-catenin pathway being upregulated during early-stages and the Wnt/PCP pathway being upregulated during late-stages. Our results demonstrate the diversity of Wnt signaling during intestinal regeneration, highlighting possible roles in adult organogenesis. Full article

Background: Treatment and outcomes of breast cancer, one of the most prevalent female cancers, have improved in recent decades. However, metastatic breast cancer remains incurable in most cases, and new therapies are needed to ameliorate prognosis. Planar cell polarity (PCP) is a characteristic of epithelial cells that form layers and is integral to the communication of these cells with neighboring cells. Dysfunction of PCP is observed in cancers and may confer a targetable vulnerability. Methods: The breast cancer cohorts from The Cancer Genome Atlas (TCGA) and the METABRIC study were interrogated for molecular alterations in genes of the PCP pathway. The groups with the most prevalent alterations were characterized, and survival was compared with counterparts not possessing PCP alterations. Breast cancer cell lines with PCP alterations from the Cancer Cell Line Encyclopedia (CCLE) were interrogated for sensitivity to drugs affecting PCP. Results: Among genes of the PCP pathway, VANGL2, NOS1AP and SCRIB display amplifications in a sizable minority of breast cancers. Concomitant up-regulation at the mRNA level can be observed mostly in basal cancers, but it does not correlate well with the amplification status of the genes, as it can also be observed in non-amplified cases. In an exploration of cell line models, two of the four breast cancer cell line models with amplifications in VANGL2, NOS1AP and SCRIB display sensitivity to drugs inhibiting acyl-transferase porcupine interfering with the WNT pathway. This sensitivity suggests a possible therapeutic role of these inhibitors in cancers bearing the amplifications. Conclusion: Molecular alterations in PCP genes can be observed in breast cancers with a predilection for the basal sub-type. An imperfect correlation of copy number alterations with mRNA expression suggests that post-translational modifications are important in PCP regulation. Inhibitors of acyl-transferase porcupine may be rational candidates for combination therapy development in PCP-altered breast cancers. Full article

Cannabigerol (CBG) is a non-psychoactive phytocannabinoid present in the Cannabis sativa L. plant. In our study, CBG at the concentration of 10 µM was used to treat NSC-34 motor neuron-like cells. The aim of the study was to evaluate the effects of CBG on NSC-34 cells, using next-generation sequencing (NGS) technology. Analysis showed the activation of the WNT/planar cell polarity (PCP) pathway and Ephrin-Eph signaling. The results revealed that CBG increases the expression of genes associated with the onset process of cytoskeletal remodeling and axon guidance. Full article

Gastrulation is a critical step in the establishment of a basic body plan during development. Convergence and extension (CE) cell movements organize germ layers during gastrulation. Noncanonical Wnt signaling has been known as major signaling that regulates CE cell movement by activating Rho and Rac. In addition, Bmp molecules are expressed in the ventral side of a developing embryo, and the ventral mesoderm region undergoes minimal CE cell movement while the dorsal mesoderm undergoes dynamic cell movements. This suggests that Bmp signal gradient may affect CE cell movement. To investigate whether Bmp signaling negatively regulates CE cell movements, we performed microarray-based screening and found that the transcription of Xenopus Arhgef3.2 (Rho guanine nucleotide exchange factor) was negatively regulated by Bmp signaling. We also showed that overexpression or knockdown of Xarhgef3.2 caused gastrulation defects. Interestingly, Xarhgef3.2 controlled gastrulation cell movements through interacting with Disheveled (Dsh2) and Dsh2-associated activator of morphogenesis 1 (Daam1). Our results suggest that Bmp gradient affects gastrulation cell movement (CE) via negative regulation of Xarhgef3.2 expression. Full article

The differential activation of Wnt pathways (canonical: Wnt/β-catenin; non-canonical: planar cell polarity (PCP), Wnt/Ca²⁺) depends on the cell-specific availability and regulation of Wnt receptors, called Frizzled (FZD). FZDs selectively recruit co-receptors to activate various downstream effectors. We established a proximity ligation assay (PLA) for the detection of endogenous FZD–co-receptor interactions and analyzed time-dependent Wnt pathway activation in cultured cells. Prostate cancer cells (PC-3) stimulated by Wnt ligands (Wnt5A, Wnt10B) were analyzed by Cy3-PLA for the co-localization of FZD6 and co-receptors (canonical: LRP6, non-canonical: ROR1) at the single-cell level. Downstream effector activation was assayed by immunocytochemistry. PLA allowed the specific (siRNA-verified) detection of FZD6–LRP6 and FZD6–ROR1 complexes as highly fluorescent spots. Incubation with Wnt10B led to increased FZD6–LRP6 interactions after 2 to 4 min and resulted in nuclear accumulation of β-catenin within 5 min. Wnt5A stimulation resulted in a higher number of FZD6–ROR1 complexes after 2 min. Elevated levels of phosphorylated myosin phosphatase target 1 suggested subsequent Wnt/PCP activation in PC-3. This is the first study demonstrating time-dependent interactions of endogenous Wnt (co-)receptors followed by rapid Wnt/β-catenin and Wnt/PCP activation in PC-3. In conclusion, the PLA could uncover novel signatures of Wnt receptor activation in mammalian cells and may provide new insights into involved signaling routes. Full article

Emerging evidence has shown the oncogenic roles of leptin in modulating cancer progression in addition to its original roles. Analyses of transcriptomic data and patients’ clinical information have revealed leptin’s prognostic significance in renal cell carcinoma (RCC). However, its biological effects on RCC progression have not yet been explored. Clinical and transcriptomic data of a RCC cohort of 603 patients were retrieved from The Cancer Genome Atlas (TCGA) and analyzed to reveal the correlation of leptin with clinical outcomes and the hierarchical clustering of gene signatures based on leptin levels. In addition, cox univariate and multivariate regression analyses, cell migration upon leptin treatment, identification of putative leptin-regulated canonical pathways via ingenuity pathway analysis (IPA), and the investigation of induction of Wnt5a, ROR2, and Jun N-terminal Kinases (JNK) phosphorylation activation were performed. We first observed a correlation of high leptin levels and poor outcomes in RCC patients. Knowledge-based analysis by IPA indicated the induction of cancer cell migration by leptin, which was manifested via direct leptin treatment in the RCC cell lines. In RCC patients with high leptin levels, the planar cell polarity (PCP)/JNK signaling pathway was shown to be activated, and genes in the axis, including CTHRC1, FZD2, FZD10, ROR2, WNT2, WNT4, WNT10B, WNT5A, WNT5B, and WNT7B, were upregulated. All of these genes were associated with unfavorable clinical outcomes. WNT5A and ROR2 are pivotal upstream regulators of PCP/JNK signaling, and their correlations with leptin expression levels were displayed by a Pearson correlation analysis. The inhibition of signal transduction by SP600125 reversed leptin-mediated cell migration properties in RCC cell lines. The results indicate the prognostic impact of leptin on RCC patients and uncover its ability to promote cell migration via PCP/JNK signaling. Full article

MicroRNAs are frequently clustered in the genome and polycistronically transcribed, regulating targeted genes in diverse signaling pathways. The miR-17-92 cluster is a typical miRNA cluster, playing crucial roles in the organogenesis and homeostasis of physiological processes in vertebrates. Here, we identified three miRNAs (csa-miR-92a, csa-miR-92b, and csa-miR-92c) that belonged to the miR-92 family and formed a miRNA cluster in the genome of a urochordate marine ascidian Ciona savignyi. Except for miR-92a and miR-92b, other homologs of the vertebrate miR-17-92 cluster members could not be identified in the Ciona genome. We further found that the mature sequences of urochordate miR-92 family members were highly conserved compared with the vertebrate species. The expression pattern revealed that three miR-92 family members had consistent expression levels in adult tissues and were predominantly expressed in heart and muscle tissue. We further showed that, at the embryonic and larval stages, csa-miR-92c was expressed in the notochord of embryos during 18–31 h post fertilization (hpf) by in situ hybridization. Knockout of csa-miR-92c resulted in the disorganization of notochord cells and the block of lumen coalescence in the notochord. Fibroblast growth factor (FGF), mitogen-activated protein kinase (MAPK), and wingless/integrated (Wnt)/planar cell polarity (PCP) signaling pathways might be involved in the regulatory processes, since a large number of core genes of these pathways were the predicted target genes of the miR-92 family. Taken together, we identified a miR-92 cluster in urochordate Ciona and revealed the expression patterns and the regulatory roles of its members in organogenesis. Our results provide expression and phylogenetic data on the understanding of the miR-92 miRNA cluster’s function during evolution. Full article