Bridging the gap between non-canonical and canonical Wnt signaling through Vangl2

Nkd1 functions downstream of Axin2 to attenuate Wnt signaling

Wnt signaling is a crucial developmental pathway involved in early development as well as stem-cell maintenance in adults and its misregulation leads to numerous diseases. Thus, understanding the regulation of this pathway becomes vitally important. Axin2 and Nkd1 are widely utilized negative feedback regulators in Wnt signaling where Axin2 functions to destabilize cytoplasmic β-catenin, and Nkd1 functions to inhibit the nuclear localization of β-catenin. Here, we set out to further understand how Axin2 and Nkd1 regulate Wnt signaling by creating axin2gh1/gh1, nkd1gh2/gh2 single mutants and axin2gh1/gh1;nkd1gh2/gh2 double mutant zebrafish using sgRNA/Cas9. All three Wnt regulator mutants were viable and had impaired heart looping, neuromast migration defects, and behavior abnormalities in common, but there were no signs of synergy in the axin2gh1/gh1;nkd1gh2/gh2 double mutants. Further, Wnt target gene expression by qRT-PCR and RNA-seq, and protein expression by mass spectrometry demonstrated that the double axin2gh1/gh1;nkd1gh2/gh2 mutant resembled the nkd1gh2/gh2 phenotype demonstrating that Nkd1 functions downstream of Axin2. In support of this, the data further demonstrates that Axin2 uniquely alters the properties of β-catenin-dependent transcription having novel readouts of Wnt activity compared with nkd1gh2/gh2 or the axin2gh1/gh1;nkd1gh2/gh2 double mutant. We also investigated the sensitivity of the Wnt regulator mutants to exacerbated Wnt signaling, where the single mutants displayed characteristic heightened Wnt sensitivity, resulting in an eyeless phenotype. Surprisingly, this phenotype was rescued in the double mutant, where we speculate that cross-talk between Wnt/β-catenin and Wnt/Planar Cell Polarity pathways could lead to altered Wnt signaling in some scenarios. Collectively, the data emphasizes both the commonality and the complexity in the feedback regulation of Wnt signaling.

The signaling pathways involved in non-coding RNA regulation during osteogenic differentiation of periodontal tissue-derived cells in the field of periodontitis

Periodontitis is a prevalent oral disease caused by chronic inflammation of the periodontal tissues surrounding the teeth, which can lead to bone loss, tooth loosening, and even tooth loss. This inflammation has a negative impact on the osteogenic differentiation capacity of periodontal tissue-derived cells. Non-coding RNAs (ncRNAs) are a class of RNA molecules that do not encode proteins but can regulate various physiological processes. In this review, we summarized the critical signaling pathways that ncRNAs modulate in osteogenic differentiation of periodontal tissue-derived cells, such as the Wnt, BMP/Smad, NF-κB, and PI3-K/Akt/mTOR pathways. This comprehensive exploration of ncRNA-mediated modulation offers fresh and promising insights for prospective approaches in the management of periodontitis and the advancement of periodontal regeneration therapies.

Wnt5a/Ca2+ signaling regulates silica-induced ferroptosis in mouse macrophages by altering ER stress-mediated redox balance

Silicosis is a chronic pulmonary disease characterized by diffuse fibrosis of lung caused by the deposition of silica dust (SiO₂). The inhaled silica-induced oxidative stress, ROS production and macrophage ferroptosis are key drivers of the pathological process of silicosis. However, mechanisms that involved in the silica-induced macrophage ferroptosis and its contributions to pathogenesis of silicosis remain elusive. In the present study, we showed that silica induced murine macrophage ferroptosis, accompanied by elevation of inflammatory responses, Wnt5a/Ca²⁺ signaling activation, and concurrent increase of endoplasmic reticulum (ER) stress and mitochondrial redox imbalance in vitro and vivo. Mechanistic study further demonstrated that Wnt5a/Ca²⁺ signaling played a key role in silica-induced macrophage ferroptosis by modulating ER stress and mitochondrial redox balance. The presence of Wnt5a/Ca²⁺ signaling ligand Wnt5a protein increased the silica-induced macrophage ferroptosis by activating ER-mediated immunoglobulin heavy chain binding protein (Bip)-C/EBP homology protein (Chop) signaling cascade, reducing the expression of negative regulators of ferroptosis, glutathione peroxidase 4 (Gpx4) and solute carrier family 7 member 11 (Slc7a11), subsequentially increasing lipid peroxidation. The pharmacologic inhibition of Wnt5a signaling or block of calcium flow exhibited an opposite effect to Wnt5a, resulted in the reduction of ferroptosis and the expression of Bip-Chop signaling molecules. These findings were further corroborated by the addition of ferroptosis activator Erastin or inhibitor ferrostatin-1. These results provide a mechanism by which silica activates Wnt5a/Ca²⁺ signaling and ER stress, sequentially leads to redox imbalance and ferroptosis in mouse macrophage cells.

Wnt4 and ephrinB2 instruct apical constriction via Dishevelled and non-canonical signaling

Apical constriction is a cell shape change critical to vertebrate neural tube closure, and the contractile force required for this process is generated by actin-myosin networks. The signaling cue that instructs this process has remained elusive. Here, we identify Wnt4 and the transmembrane ephrinB2 protein as playing an instructive role in neural tube closure as members of a signaling complex we termed WERDS (Wnt4, EphrinB2, Ror2, Dishevelled (Dsh2), and Shroom3). Disruption of function or interaction among members of the WERDS complex results in defects of apical constriction and neural tube closure. The mechanism of action involves an interaction of ephrinB2 with the Dsh2 scaffold protein that enhances the formation of the WERDS complex, which in turn, activates Rho-associated kinase to induce apical constriction. Moreover, the ephrinB2/Dsh2 interaction promotes non-canonical Wnt signaling and shows how cross-talk between two major signal transduction pathways, Eph/ephrin and Wnt, coordinate morphogenesis of the neural tube.

Drugs and Endogenous Factors as Protagonists in Neurogenic Stimulation

Neurogenesis is a biological process characterized by new neurons formation from stem cells. For decades, it was believed that neurons only multiplied during development and in the postnatal period but the discovery of neural stem cells (NSCs) in mature brain promoted a revolution in neuroscience field. In mammals, neurogenesis consists of migration, differentiation, maturation, as well as functional integration of newborn cells into the pre-existing neuronal circuit. Actually, NSC density drops significantly after the first stages of development, however in specific places in the brain, called neurogenic niches, some of these cells retain their ability to generate new neurons and glial cells in adulthood. The subgranular (SGZ), and the subventricular zones (SVZ) are examples of regions where the neurogenesis process occurs in the mature brain. There, the potential of NSCs to produce new neurons has been explored by new advanced methodologies and in neuroscience for the treatment of brain damage and/or degeneration. Based on that, this review highlights endogenous factors and drugs capable of stimulating neurogenesis, as well as the perspectives for the use of NSCs for neurological and neurodegenerative diseases.

Analysis of Gene-Environment Interactions Related to Developmental Disorders

Various genetic and environmental factors are associated with developmental disorders (DDs). It has been suggested that interaction between genetic and environmental factors (G × E) is involved in the etiology of DDs. There are two major approaches to analyze the interaction: genome-wide and candidate gene-based approaches. In this mini-review, we demonstrate how these approaches can be applied to reveal the G × E related to DDs focusing on zebrafish and mouse models. We also discuss novel approaches to analyze the G × E associated with DDs.

Roles of lncRNAs Mediating Wnt/β-Catenin Signaling in HCC

Hepatocellular carcinoma (HCC) is considered the second most deadly cancer worldwide. Due to the absence of early diagnostic markers and effective therapeutic approaches, distant metastasis and increasing recurrence rates are major difficulties in the clinical treatment of HCC. Further understanding of its pathogenesis has become an urgent goal in HCC research. Recently, abnormal expression of long noncoding RNAs (lncRNAs) was identified as a vital regulator involved in the initiation and development of HCC. Activation of the Wnt/β-catenin pathway has been reported to obviously impact cell proliferation, invasion, and migration of HCC. This article reviews specific interactions, significant mechanisms and molecules related to HCC initiation and progression to provide promising strategies for treatment.

Phosphorylation-Dependent Regulation of WNT/Beta-Catenin Signaling

WNT/β-catenin signaling is a highly complex pathway that plays diverse roles in various cellular processes. While WNT ligands usually signal through their dedicated Frizzled receptors, the decision to signal in a β-catenin-dependent or -independent manner rests upon the type of co-receptors used. Canonical WNT signaling is β-catenin-dependent, whereas non-canonical WNT signaling is β-catenin-independent according to the classical definition. This still holds true, albeit with some added complexity, as both the pathways seem to cross-talk with intertwined networks that involve the use of different ligands, receptors, and co-receptors. β-catenin can be directly phosphorylated by various kinases governing its participation in either canonical or non-canonical pathways. Moreover, the co-activators that associate with β-catenin determine the output of the pathway in terms of induction of genes promoting proliferation or differentiation. In this review, we provide an overview of how protein phosphorylation controls WNT/β-catenin signaling, particularly in human cancer.