The planar cell polarity Vangl2 protein: From genetics to cellular and molecular functions

PCP protein Prickle 1 regulates Sertoli cell and testis function via cytoskeletal organization through the recruitment of multiple regulatory proteins

Prickle 1, an ortholog found in Drosophila, was localized at the Sertoli cell-spermatid interface consistent with its role of supporting the Vangl2 planar cell polarity (PCP), which is an integral membrane protein that creates the PCP protein complex of Vangl2 (Van Gogh-like 2)/Prickle1. Together with the asymmetrically localized transmembrane protein Frizzled (Fzd) and its unique adaptor proteins Disheveled (Dvl) and Inversin (Inv), Vangl2/Prickle1 and Fzd/Dvl/Inv are the two heterodimeric interacting PCP proteins between Sertoli cells and condensed spermatids to confer spermatid PCP across the plane of the seminiferous epithelium. Our initial intention was to examine if the distribution and expression of Prickle1 using a primary Sertoli cell in vitro model and Sprague-Dawley rats in vivo would mimic much of the earlier reported findings of Vangl2. Unexpectedly, these findings indicated that Prickle1 supported the PCP protein Vangl2; however, Prickle1 is also a multifunctional protein. First, Prickle1 knockdown (KD) by RNAi impeded Sertoli cell TJ function by perturbing the distribution of the BTB-associated proteins at the cell-cell interface, through disruption of the microtubule (MT) and actin cytoskeletal organization including their respective polymerization (and/or bundling) capability. Second, these findings were reproduced using an in vivo model of RNAi by KD of Prickle 1 in the testis. Third, using coimmunoprecipitation (Co-IP), Prickle 1 was found to interact with a host of adaptor proteins crucial to support not only PCP, such as Dvl, but also regulatory cytoskeletal proteins of MT and actin networks, including RhoA, Arp3, Cdc42, ZO-1, and β-catenin by immunoprecipitation-mass spectrometry (IP-MS) using the String Protein Interaction Tool.NEW & NOTEWORTHY This article was written based on results from a series of experiments to understand the function of planar cell polarity (PCP) protein Prickle 1 in the testis to support spermatogenesis. It was unexpectedly shown that Prickle1 was found to recruit several important regulatory proteins at the site where the Sertoli cell and condensed spermatids interact to modulate cytoskeletal functions of both actin and microtubule. These findings are important to both cell and molecular biologists.

VANGL2 downregulates HINT1 to inhibit the ATM-p53 pathway and promote cisplatin resistance in small cell lung cancer

Cisplatin is a first-line drug for the treatment of small cell lung cancer (SCLC). Although the majority of patients with SCLC initially respond to cisplatin therapy, cisplatin resistance readily develops, leading to tumor progression. Therefore, this study aims to elucidate the mechanisms underlying cisplatin resistance in SCLC. We found that VANGL2 is a poor prognostic factor and promotes cisplatin resistance in SCLC. Mechanistically, in cisplatin-resistant cells, VANGL2 overexpression leads to the autophagic degradation of HINT1. This reduction in HINT1 expression further reduces the phosphorylation of ATM and p53 induced by cisplatin-mediated DNA damage. The decreased phosphorylation of p53 inhibits downstream apoptotic pathways, thereby reducing cisplatin-induced apoptosis. In conclusion, VANGL2 regulates the ATM-p53 pathway-mediated apoptotic response of SCLC to cisplatin by downregulating HINT1, thereby promoting cisplatin resistance. Thus, VANGL2 may serve as a potential therapeutic target for reversing cisplatin resistance in SCLC patients.

VANGL2 alleviates inflammatory bowel disease by recruiting the ubiquitin ligase MARCH8 to limit NLRP3 inflammasome activation through OPTN-mediated selective autophagy

Inflammatory bowel disease (IBD) is a chronic and potentially life-threatening inflammatory disease of gastroenteric tissue characterized by episodes of intestinal inflammation, but the underlying mechanisms remain elusive. Here, we explore the role and precise mechanism of Van-Gogh-like 2 (VANGL2) during the pathogenesis of IBD. VANGL2 decreases in IBD patients and dextran sulfate sodium (DSS)-induced colitis in mice. Myeloid VANGL2 deficiency exacerbates the progression of DSS-induced colitis in mice and specifically enhances the activation of NLRP3 inflammasome in macrophages. NLRP3-specific inhibitor MCC950 effectively alleviates DSS-induced colitis in VANGL2 deficient mice. Mechanistically, VANGL2 interacts with NLRP3 and promotes the autophagic degradation of NLRP3 through enhancing the K27-linked polyubiquitination at lysine 823 of NLRP3 by recruiting E3 ligase MARCH8, leading to optineurin (OPTN)-mediated selective autophagy. Notably, decreased VANGL2 in the peripheral blood mononuclear cells from IBD patients results in overt NLRP3 inflammasome activation and sustained inflammation. Taken together, this study demonstrates that VANGL2 acts as a repressor of IBD progression by inhibiting NLRP3 inflammasome activation and provides insights into the crosstalk between inflammation and autophagy in preventing IBD.

Vangl2 regulates intercellular junctions by remodeling actin-based cytoskeleton through the Rock signaling pathway during spermatogenesis in Eriocheir sinensis

As a key planar cell polarity protein, Van Gogh-like 2 (Vangl2) is essential for mammalian spermatogenesis. As a decapod crustacean, Eriocheir sinensis exhibits distinct spermatogenic processes due to its unique seminiferous tubule morphology and hemolymph-testis barrier (HTB). To determine whether Vangl2 performs analogous functions in E. sinensis, we identified the Es-Vangl2. Es-Vangl2 exhibited high expression and wide distribution in the testes, indicating its crucial involvement in spermatogenesis. Following targeted knockdown of Es-Vangl2in vivo, the structure of seminiferous tubules was disrupted, characterized by vacuolization of the germinal zone and obstruction of spermatozoon release. Concurrently, the integrity of the HTB was compromised, accompanied by reduced expression and aberrant localization of junction proteins. More importantly, the regulatory influence of Es-Vangl2 was manifested through modulating the organization of microfilaments, a process mediated by epidermal growth factor receptor pathway substrate 8 (Eps8). Further studies demonstrated that these phenotypes resulting from Es-Vangl2 knockdown were attributed to the inhibition of Rock signaling pathway activity, which was verified by the Es-Rock interference and Y27632 inhibition assays. In summary, the findings highlight the pivotal role of Es-Vangl2 in stabilizing HTB integrity by regulating Eps8-mediated actin remodeling through the Rock signaling pathway in the spermatogenesis of E. sinensis.

Vangl2 suppresses NF-κB signaling and ameliorates sepsis by targeting p65 for NDP52-mediated autophagic degradation

Van Gogh-like 2 (Vangl2), a core planar cell polarity component, plays an important role in polarized cellular and tissue morphology induction, growth development, and cancer. However, its role in regulating inflammatory responses remains elusive. Here, we report that Vangl2 is upregulated in patients with sepsis and identify Vangl2 as a negative regulator of The nuclear factor-kappaB (NF-κB) signaling by regulating the protein stability and activation of the core transcription component p65. Mice with myeloid-specific deletion of Vangl2 (Vangl2ΔM) are hypersusceptible to lipopolysaccharide (LPS)-induced septic shock. Vangl2-deficient myeloid cells exhibit enhanced phosphorylation and expression of p65, therefore, promoting the secretion of proinflammatory cytokines after LPS stimulation. Mechanistically, NF-κB signaling-induced-Vangl2 recruits E3 ubiquitin ligase PDLIM2 to catalyze K63-linked ubiquitination on p65, which serves as a recognition signal for cargo receptor NDP52-mediated selective autophagic degradation. Taken together, these findings demonstrate Vangl2 as a suppressor of NF-κB-mediated inflammation and provide insights into the crosstalk between autophagy and inflammatory diseases.

Stearoylation cycle regulates the cell surface distribution of the PCP protein Vangl2

Defects in planar cell polarity (PCP) have been implicated in diverse human pathologies. Vangl2 is one of the core PCP components crucial for PCP signaling. Dysregulation of Vangl2 has been associated with severe neural tube defects and cancers. However, how Vangl2 protein is regulated at the posttranslational level has not been well understood. Using chemical reporters of fatty acylation and biochemical validation, here we present that Vangl2 subcellular localization is regulated by a reversible S-stearoylation cycle. The dynamic process is mainly regulated by acyltransferase ZDHHC9 and deacylase acyl-protein thioesterase 1 (APT1). The stearoylation-deficient mutant of Vangl2 shows decreased plasma membrane localization, resulting in disruption of PCP establishment during cell migration. Genetically or pharmacologically inhibiting ZDHHC9 phenocopies the effects of the stearoylation loss of Vangl2. In addition, loss of Vangl2 stearoylation enhances the activation of oncogenic Yes-associated protein 1 (YAP), serine-threonine kinase AKT, and extracellular signal-regulated protein kinase (ERK) signaling and promotes breast cancer cell growth and HRas G12V mutant (HRasV12)-induced oncogenic transformation. Our results reveal a regulation mechanism of Vangl2, and provide mechanistic insight into how fatty acid metabolism and protein fatty acylation regulate PCP signaling and tumorigenesis by core PCP protein lipidation.

PDZome-wide and structural characterization of the PDZ-binding motif of VANGL2

VANGL2 is a core component of the non-canonical Wnt/Planar Cell Polarity signaling pathway that uses its highly conserved carboxy-terminal type 1 PDZ-binding motif (PBM) to bind a variety of PDZ proteins. In this study, we characterize and quantitatively assess the largest VANGL2 PDZome-binding profile documented so far, using orthogonal methods. The results of our holdup approach support VANGL2 interactions with a large panel of both long-recognized and unprecedented PDZ domains. Truncation and point mutation analyses of the VANGL2 PBM establish that, beyond the strict requirement of the P-0 / V521 and P-2 / T519 amino acids, upstream residues, including E518, Q516 and R514 at, respectively, P-3, P-5 and P-7 further contribute to the robustness of VANGL2 interactions with two distinct PDZ domains, SNX27 and SCRIBBLE-PDZ3. In agreement with these data, incremental amino-terminal deletions of the VANGL2 PBM causes its overall affinity to progressively decline. Moreover, the holdup data establish that the PDZome binding repertoire of VANGL2 starts to diverge significantly with the truncation of E518. A structural analysis of the SYNJ2BP-PDZ/VANGL2 interaction with truncated PBMs identifies a major conformational change in the binding direction of the PBM peptide after the P-2 position. Finally, we report that the PDZome binding profile of VANGL2 is dramatically rearranged upon phosphorylation of S517, T519 and S520. Our crystallographic approach illustrates how SYNJ2BP accommodates a S520-phosphorylated PBM peptide through the ideal positioning of two basic residues, K48 and R86. Altogether our data provides a comprehensive view of the VANGL2 PDZ network and how this network specifically responds to the post-translation modification of distinct PBM residues. These findings should prove useful in guiding future functional and molecular studies of the key PCP component VANGL2.

Core planar cell polarity genes VANGL1 and VANGL2 in predisposition to congenital vertebral malformations

Congenital scoliosis (CS), affecting approximately 0.5 to 1 in 1,000 live births, is commonly caused by congenital vertebral malformations (CVMs) arising from aberrant somitogenesis or somite differentiation. While Wnt/ß-catenin signaling has been implicated in somite development, the function of Wnt/planar cell polarity (Wnt/PCP) signaling in this process remains unclear. Here, we investigated the role of Vangl1 and Vangl2 in vertebral development and found that their deletion causes vertebral anomalies resembling human CVMs. Analysis of exome sequencing data from multiethnic CS patients revealed a number of rare and deleterious variants in VANGL1 and VANGL2, many of which exhibited loss-of-function and dominant-negative effects. Zebrafish models confirmed the pathogenicity of these variants. Furthermore, we found that Vangl1 knock-in (p.R258H) mice exhibited vertebral malformations in a Vangl gene dose- and environment-dependent manner. Our findings highlight critical roles for PCP signaling in vertebral development and predisposition to CVMs in CS patients, providing insights into the molecular mechanisms underlying this disorder.

Nuclear VANGL2 Inhibits Lactogenic Differentiation

Planar cell polarity (PCP) proteins coordinate tissue morphogenesis by governing cell patterning and polarity. Asymmetrically localized on the plasma membrane of cells, transmembrane PCP proteins are trafficked by endocytosis, suggesting they may have intracellular functions that are dependent or independent of their extracellular role, but whether these functions extend to transcriptional control remains unknown. Here, we show the nuclear localization of transmembrane, PCP protein, VANGL2, in the HCC1569 breast cancer cell line, and in undifferentiated, but not differentiated, HC11 cells that serve as a model for mammary lactogenic differentiation. The loss of Vangl2 function results in upregulation of pathways related to STAT5 signaling. We identify DNA binding sites and a nuclear localization signal in VANGL2, and use CUT&RUN to demonstrate recruitment of VANGL2 to specific DNA binding motifs, including one in the Stat5a promoter. Knockdown (KD) of Vangl2 in HC11 cells and primary mammary organoids results in upregulation of Stat5a, Ccnd1 and Csn2, larger acini and organoids, and precocious differentiation; phenotypes are rescued by overexpression of Vangl2, but not Vangl2ΔNLS. Together, these results advance a paradigm whereby PCP proteins coordinate tissue morphogenesis by keeping transcriptional programs governing differentiation in check.

Functional analysis of germline VANGL2 variants using rescue assays of vangl2 knockout zebrafish

Developmental studies have shown that the evolutionarily conserved Wnt Planar Cell Polarity (PCP) pathway is essential for the development of a diverse range of tissues and organs including the brain, spinal cord, heart and sensory organs, as well as establishment of the left-right body axis. Germline mutations in the highly conserved PCP gene VANGL2 in humans have only been associated with central nervous system malformations, and functional testing to understand variant impact has not been performed. Here we report three new families with missense variants in VANGL2 associated with heterotaxy and congenital heart disease p.(Arg169His), non-syndromic hearing loss p.(Glu465Ala) and congenital heart disease with brain defects p.(Arg135Trp). To test the in vivo impact of these and previously described variants, we have established clinically-relevant assays using mRNA rescue of the vangl2 mutant zebrafish. We show that all variants disrupt Vangl2 function, although to different extents and depending on the developmental process. We also begin to identify that different VANGL2 missense variants may be haploinsufficient and discuss evidence in support of pathogenicity. Together, this study demonstrates that zebrafish present a suitable pipeline to investigate variants of unknown significance and suggests new avenues for investigation of the different developmental contexts of VANGL2 function that are clinically meaningful.

Nuclear VANGL2 Inhibits Lactogenic Differentiation

Planar cell polarity (PCP) proteins coordinate tissue morphogenesis by governing cell patterning and polarity. Asymmetrically localized on the plasma membrane of cells, PCP proteins are also trafficked by endocytosis, suggesting they may have intracellular functions that are dependent or independent of their extracellular role, but whether these functions extend to transcriptional control remains unknown. Here, we show the nuclear localization of transmembrane, PCP protein, VANGL2, in undifferentiated, but not differentiated, HC11 cells, which serve as a model for mammary lactogenic differentiation. Loss of Vangl2 function results in upregulation of pathways related to STAT5 signaling. We identify DNA binding sites and a nuclear localization signal in VANGL2, and use CUT&RUN to demonstrate direct binding of VANGL2 to specific DNA binding motifs, including one in the Stat5a promoter. Knockdown (KD) of Vangl2 in HC11 cells and primary mammary organoids results in upregulation of Stat5a , Ccnd1 and Csn2 , larger acini and organoids, and precocious differentiation; phenotypes rescued by overexpression of Vangl2 , but not Vangl2 ΔNLS . Together, these results advance a paradigm whereby PCP proteins coordinate tissue morphogenesis by keeping transcriptional programs governing differentiation in check.

Transcriptome profiling analysis of uterus during chicken laying periods

The avian eggshell is formed in the uterus. Changes in uterine function may have a significant effect on eggshell quality. To identify the vital genes impacting uterine functional maintenance in the chicken, uteri in three different periods (22W, 31W, 51W) were selected for RNA sequencing and bioinformatics analysis. In our study, 520, 706 and 736 differentially expressed genes (DEGs) were respectively detected in the W31 vs W22 group, W51 vs W31 group and W51 vs W22 group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated DEGs were enriched in the extracellular matrix, extracellular region part, extracellular region, extracellular matrix structural constituent, ECM receptor interaction, collagen-containing extracellular matrix and collagen trimer in the uterus (P < 0.05). Protein-protein interaction analysis revealed that FN1, LOX, THBS2, COL1A1, COL1A2, COL5A1, COL5A2, POSTN, MMP13, VANGL2, RAD54B, SPP1, SDC1, BTC, ANGPTL3 might be key candidate genes for uterine functional maintenance in chicken. This study discovered dominant genes and pathways which enhanced our knowledge of chicken uterine functional maintenance.

An interaction between OTULIN and SCRIB uncovers roles for linear ubiquitination in planar cell polarity

Planar cell polarity (PCP) plays critical roles in developmental and homeostatic processes. Membrane presentation of PCP complexes containing Van Gogh-like (VANGL) transmembrane proteins is central to PCP and can be directed by the scaffold protein scribble (SCRIB). The role atypical linear ubiquitin (Met1-Ub) chains might play in PCP is unknown. Here, HEK293 cell-based interactomic analyses of the Met1-Ub deubiquitinase OTULIN revealed that OTULIN can interact with SCRIB. Moreover, Met1-Ub chains associated with VANGL2 and PRICKLE1, but not SCRIB, can direct VANGL2 surface presentation. Mouse embryos lacking Otulin showed variable neural tube malformations, including rare open neural tubes, a deficit associated with PCP disruption in mice. In Madin-Darby canine kidney cells, in which the enrichment of VANGL2-GFP proteins at cell-cell contacts represents activated PCP complexes, endogenous OTULIN was recruited to these sites. In the human MDA-MB-231 breast cancer cell model, OTULIN loss caused deficits in Wnt5a-induced filopodia extension and trafficking of transfected HA-VANGL2. Taken together, these findings support a role for linear (de)ubiquitination in PCP signaling. The association of Met1-Ub chains with PCP complex components offers new opportunities for integrating PCP signaling with OTULIN-dependent immune and inflammatory pathways.

The Helicobacter pylori CagA oncoprotein disrupts Wnt/PCP signaling and promotes hyperproliferation of pyloric gland base cells

Helicobacter pylori strains that deliver the oncoprotein CagA into gastric epithelial cells are the major etiologic agents of upper gastric diseases including gastric cancer. CagA promotes gastric carcinogenesis through interactions with multiple host proteins. Here, we show that CagA also disrupts Wnt-dependent planar cell polarity (Wnt/PCP), which orients cells within the plane of an epithelium and coordinates collective cell behaviors such as convergent extension to enable epithelial elongation during development. Ectopic expression of CagA in Xenopus laevis embryos impaired gastrulation, neural tube formation, and axis elongation, processes driven by convergent extension movements that depend on the Wnt/PCP pathway. Mice specifically expressing CagA in the stomach epithelium had longer pyloric glands and mislocalization of the tetraspanin proteins VANGL1 and VANGL2 (VANGL1/2), which are critical components of Wnt/PCP signaling. The increased pyloric gland length was due to hyperproliferation of cells at the gland base, where Lgr5⁺ stem and progenitor cells reside, and was associated with fewer differentiated enteroendocrine cells. In cultured human gastric epithelial cells, the N terminus of CagA interacted with the C-terminal cytoplasmic tails of VANGL1/2, which impaired Wnt/PCP signaling by inducing the mislocalization of VANGL1/2 from the plasma membrane to the cytoplasm. Thus, CagA may contribute to the development of gastric cancer by subverting a Wnt/PCP-dependent mechanism that restrains pyloric gland stem cell proliferation and promotes enteroendocrine differentiation.

VANGL2 inhibits antiviral IFN-I signaling by targeting TBK1 for autophagic degradation

Stringent control of type I interferon (IFN-I) signaling is critical to potent innate immune responses against viral infection, yet the underlying molecular mechanisms are still elusive. Here, we found that Van Gogh-like 2 (VANGL2) acts as an IFN-inducible negative feedback regulator to suppress IFN-I signaling during vesicular stomatitis virus (VSV) infection. Mechanistically, VANGL2 interacted with TBK1 and promoted the selective autophagic degradation of TBK1 via K48-linked polyubiquitination at Lys372 by the E3 ligase TRIP, which serves as a recognition signal for the cargo receptor OPTN. Furthermore, myeloid-specific deletion of VANGL2 in mice showed enhanced IFN-I production against VSV infection and improved survival. In general, these findings revealed a negative feedback loop of IFN-I signaling through the VANGL2-TRIP-TBK1-OPTN axis and highlighted the cross-talk between IFN-I and autophagy in preventing viral infection. VANGL2 could be a potential clinical therapeutic target for viral infectious diseases, including COVID-19.

Functional interaction between Vangl2 and N-cadherin regulates planar cell polarization of the developing neural tube and cochlear sensory epithelium

Although the core constituents of the Wnt/planar cell polarity (PCP) signaling have been extensively studied, their downstream molecules and protein-protein interactions have not yet been fully elucidated. Here, we show genetic and molecular evidence that the PCP factor, Vangl2, functionally interacts with the cell-cell adhesion molecule, N-cadherin (also known as Cdh2), for typical PCP-dependent neural development. Vangl2 and N-cadherin physically interact in the neural plates undergoing convergent extension. Unlike monogenic heterozygotes, digenic heterozygous mice with Vangl2 and Cdh2 mutants exhibited defects in neural tube closure and cochlear hair cell orientation. Despite this genetic interaction, neuroepithelial cells derived from the digenic heterozygotes did not show additive changes from the monogenic heterozygotes of Vangl2 in the RhoA-ROCK-Mypt1 and c-Jun N-terminal kinase (JNK)-Jun pathways of Wnt/PCP signaling. Thus, cooperation between Vangl2 and N-cadherin is at least partly via direct molecular interaction; it is essential for the planar polarized development of neural tissues but not significantly associated with RhoA or JNK pathways.

A stem cell roadmap of ribosome heterogeneity reveals a function for RPL10A in mesoderm production

Recent findings suggest that the ribosome itself modulates gene expression. However, whether ribosomes change composition across cell types or control cell fate remains unknown. Here, employing quantitative mass spectrometry during human embryonic stem cell differentiation, we identify dozens of ribosome composition changes underlying cell fate specification. We observe upregulation of RPL10A/uL1-containing ribosomes in the primitive streak followed by progressive decreases during mesoderm differentiation. An Rpl10a loss-of-function allele in mice causes striking early mesodermal phenotypes, including posterior trunk truncations, and inhibits paraxial mesoderm production in culture. Ribosome profiling in Rpl10a loss-of-function mice reveals decreased translation of mesoderm regulators, including Wnt pathway mRNAs, which are also enriched on RPL10A/uL1-containing ribosomes. We further show that RPL10A/uL1 regulates canonical and non-canonical Wnt signaling during stem cell differentiation and in the developing embryo. These findings reveal unexpected ribosome composition modularity that controls differentiation and development through the specialized translation of key signaling networks.

Wnt5a-Vangl1/2 signaling regulates the position and direction of lung branching through the cytoskeleton and focal adhesions

Lung branching morphogenesis requires reciprocal interactions between the epithelium and mesenchyme. How the lung branches are generated at a defined location and projected toward a specific direction remains a major unresolved issue. In this study, we investigated the function of Wnt signaling in lung branching in mice. We discovered that Wnt5a in both the epithelium and the mesenchyme plays an essential role in controlling the position and direction of lung branching. The Wnt5a signal is mediated by Vangl1/2 to trigger a cascade of noncanonical or planar cell polarity (PCP) signaling. In response to noncanonical Wnt signaling, lung cells undergo cytoskeletal reorganization and change focal adhesions. Perturbed focal adhesions in lung explants are associated with defective branching. Moreover, we observed changes in the shape and orientation of the epithelial sheet and the underlying mesenchymal layer in regions of defective branching in the mutant lungs. Thus, PCP signaling helps define the position and orientation of the lung branches. We propose that mechanical force induced by noncanonical Wnt signaling mediates a coordinated alteration in the shape and orientation of a group of epithelial and mesenchymal cells. These results provide a new framework for understanding the molecular mechanisms by which a stereotypic branching pattern is generated.

Dihydroartemisinin Attenuates Hypoxic Pulmonary Hypertension via the Downregulation of miR-335 Targeting Vangl2

Dihydroartemisinin (DHA) is a traditional antimalarial drug. DHA plays a crucial role in preventing pulmonary hypertension (PH); however, its regulatory function on microRNAs (miRNAs) in PH remains unclear. This study aimed to investigate whether DHA exerts its protective functions by regulating miR-335 in PH. Hypoxia-induced PH models were induced both in vitro and in vivo. Mice were treated with various concentrations of DHA, and pulmonary arterial smooth muscle cells (PASMCs) were treated with DHA, miR-335 inhibitor, miR-335 mimic, or Van Gogh-like 2 (Vangl2) plasmid. The expression of miR-335 and Vangl2, pulmonary arterial remodeling index; right ventricular hypertrophy index; and proliferation and migration indexes were measured. DHA improved pulmonary vascular remodeling and alleviated PH in vivo. miRNA sequencing and real-time PCR results further show that the increase in hypoxia-induced miR-335 was avoided by DHA administration, and miR-335 increased the hypoxia-induced PASMC proliferation and migration. MiRNA databases and dual-luciferase reporter assay show that miR-335 directly targets Vangl2, and Vangl2 decreased the hypoxia-induced PASMC proliferation and migration. The miR-335 inhibitor failed to inhibit hypoxia-induced proliferation and migration upregulation in Vangl2 knockdown PASMCs, and the effect of DHA can be blocked by miR-335 upregulation. In hypoxic PH, MiR-335 is increased, whereas Vangl2 is decreased. MiR-335 can significantly promote the hypoxia-induced proliferation and migration of PASMCs by targeting the Vangl2 gene. DHA effectively reverses the hypoxia-induced upregulation of miR-335 expression, avoiding the miR-335-mediated downregulation of Vangl2 and thereby promoting the expression of Vangl2 to prevent PH.

Role of Chaperone-Mediated Autophagy in Ageing Biology and Rejuvenation of Stem Cells

What lies at the basis of the mechanisms that regulate the maintenance and self-renewal of pluripotent stem cells is still an open question. The control of stemness derives from a fine regulation between transcriptional and metabolic factors. In the last years, an emerging topic has concerned the involvement of Chaperone-Mediated Autophagy (CMA) as a key mechanism in stem cell pluripotency control acting as a bridge between epigenetic, transcriptional and differentiation regulation. This review aims to clarify this new and not yet well-explored horizon discussing the recent studies regarding the CMA impact on embryonic, mesenchymal, and haematopoietic stem cells. The review will discuss how CMA influences embryonic stem cell activity promoting self-renewal or differentiation, its involvement in maintaining haematopoietic stem cell function by increasing their functionality during the normal ageing process and its effects on mesenchymal stem cells, in which modulation of CMA regulates immunosuppressive and differentiation properties. Finally, the importance of these new discoveries and their relevance for regenerative medicine applications, from transplantation to cell rejuvenation, will be addressed.

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.

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

Non-canonical Wnt signaling (encompassing Wnt/PCP and WntCa²⁺) has a dual identity in the literature. One stream of research investigates its role in antagonizing canonical Wnt/β-catenin signaling in cancer, typically through Ca²⁺, while the other stream investigates its effect on polarity in development, typically through Vangl2. Rarely do these topics intersect or overlap. What has become clear is that Wnt5a can mobilize intracellular calcium stores to inhibit Wnt/β-catenin in cancer cells but there is no evidence that Vangl2 is involved in this process. Conversely, Wnt5a can independently activate Vangl2 to affect polarity and migration but the role of calcium in this process is also limited. Further, Vangl2 has also been implicated in inhibiting Wnt/β-catenin signaling in development. The consensus is that a cell can differentiate between canonical and non-canonical Wnt signaling when presented with a choice, always choosing non-canonical at the expense of canonical Wnt signaling. However, these are rare events in vivo. Given the shared resources between non-canonical and canonical Wnt signaling it is perplexing that there is not more in vivo evidence for cross talk between these two pathways. In this review we discuss the intersection of non-canonical Wnt, with a focus on Wnt/PCP, and Wnt/β-catenin signaling in an attempt to shed some light on pathways that rarely meet at a crossroads in vivo.

Planar cell polarity protein Vangl2 and its interacting protein Ap2m1 regulate dendritic branching in cortical neurons

Van Gogh-like 2 (Vangl2) is a mammalian homolog of Drosophila core planar cell polarity (PCP) protein Vang/Strabismus, which organizes asymmetric cell axes for developmental proliferation, fate determination, and polarized movements in multiple tissues, including neurons. Although the PCP pathway has an essential role for dendrite and dendritic spine formation, the molecular mechanism remains to be clarified. To investigate the mechanism of Vangl2-related neuronal development, we screened for proteins that interact with the Vangl2 cytosolic N-terminus from postnatal day 9 mouse brains using a yeast two-hybrid system. From 61 genes, we identified adaptor-related protein complex 2, mu 1 subunit (Ap2m1) as the Vangl2 N-terminal binding protein. Intriguingly, however, the pull-down assay demonstrated that Vangl2 interacted with Ap2m1 not only at its N-terminus but also at the C-terminal Prickle binding domain. Furthermore, we verified that the downregulation of Ap2m1 in the developing cortical neurons reduced the dendritic branching similar to what occurs in a knockdown of Vangl2. From these results, we suggest that the membrane internalization regulated by the PCP pathway is required for the developmental morphological change in neurons.

New mouse models for high resolution and live imaging of planar cell polarity proteins in vivo

The collective polarization of cellular structures and behaviors across a tissue plane is a near universal feature of epithelia known as planar cell polarity (PCP). This property is controlled by the core PCP pathway, which consists of highly conserved membrane-associated protein complexes that localize asymmetrically at cell junctions. Here, we introduce three new mouse models for investigating the localization and dynamics of transmembrane PCP proteins: Celsr1, Fz6 and Vangl2. Using the skin epidermis as a model, we characterize and verify the expression, localization and function of endogenously tagged Celsr1-3xGFP, Fz6-3xGFP and tdTomato-Vangl2 fusion proteins. Live imaging of Fz6-3xGFP in basal epidermal progenitors reveals that the polarity of the tissue is not fixed through time. Rather, asymmetry dynamically shifts during cell rearrangements and divisions, while global, average polarity of the tissue is preserved. We show using super-resolution STED imaging that Fz6-3xGFP and tdTomato-Vangl2 can be resolved, enabling us to observe their complex localization along junctions. We further explore PCP fusion protein localization in the trachea and neural tube, and discover new patterns of PCP expression and localization throughout the mouse embryo.

Vangl2 limits chaperone-mediated autophagy to balance osteogenic differentiation in mesenchymal stem cells

Lysosomes are the recycling center and nutrient signaling hub of the cell. Here, we show that lysosomes also control mesenchymal stem cell (MSC) differentiation by proteomic reprogramming. The chaperone-mediated autophagy (CMA) lysosome subgroup promotes osteogenesis, while suppressing adipogenesis, by selectively removing osteogenesis-deterring factors, especially master transcriptional factors, such as adipogenic TLE3, ZNF423, and chondrogenic SOX9. The activity of the CMA-committed lysosomes in MSCs are controlled by Van-Gogh-like 2 (Vangl2) at lysosomes. Vangl2 directly binds to lysosome-associated membrane protein 2A (LAMP-2A) and targets it for degradation. MSC-specific Vangl2 ablation in mice increases LAMP-2A expression and CMA-lysosome numbers, promoting bone formation while reducing marrow fat. The Vangl2:LAMP-2A ratio in MSCs correlates inversely with the capacity of the cells for osteoblastic differentiation in humans and mice. These findings demonstrate a critical role for lysosomes in MSC lineage acquisition and establish Vangl2-LAMP-2A signaling as a critical control mechanism.

Planar cell polarity (PCP) proteins support spermatogenesis through cytoskeletal organization in the testis

Few reports are found in the literature regarding the role of planar cell polarity (PCP) in supporting spermatogenesis in the testis. Yet morphological studies reported decades earlier have illustrated the directional alignment of polarized developing spermatids, most notably step 17-19 spermatids in stage V-early VIII tubules in the testis, across the plane of the epithelium in seminiferous tubules of adult rats. Such morphological features have unequivocally demonstrated the presence of PCP in developing spermatids, analogous to the PCP noted in hair cells of the cochlea in mammals. Emerging evidence in recent years has shown that Sertoli and germ cells express numerous PCP proteins, mostly notably, the core PCP proteins, PCP effectors and PCP signaling proteins. In this review, we discuss recent findings in the field regarding the two core PCP protein complexes, namely the Van Gogh-like 2 (Vangl2)/Prickle (Pk) complex and the Frizzled (Fzd)/Dishevelled (Dvl) complex. These findings have illustrated that these PCP proteins exert their regulatory role to support spermatogenesis through changes in the organization of actin and microtubule (MT) cytoskeletons in Sertoli cells. For instance, these PCP proteins confer PCP to developing spermatids. As such, developing haploid spermatids can be aligned and orderly packed within the limited space of the seminiferous tubules in the testes for the production of sperm via spermatogenesis. Thus, each adult male in the mouse, rat or human can produce an upward of 30, 50 or 300 million spermatozoa on a daily basis, respectively, throughout the adulthood. We also highlight critical areas of research that deserve attention in future studies. We also provide a hypothetical model by which PCP proteins support spermatogenesis based on recent studies in the testis. It is conceivable that the hypothetical model shown here will be updated as more data become available in future years, but this information can serve as the framework by investigators to unravel the role of PCP in spermatogenesis.

Apical Restriction of the Planar Cell Polarity Component VANGL in Pancreatic Ducts Is Required to Maintain Epithelial Integrity

Cell polarity is essential for the architecture and function of numerous epithelial tissues. Here, we show that apical restriction of planar cell polarity (PCP) components is necessary for the maintenance of epithelial integrity. Using the mammalian pancreas as a model, we find that components of the core PCP pathway, such as the transmembrane protein Van Gogh-like (VANGL), become apically restricted over a period of several days. Expansion of VANGL localization to the basolateral membranes of progenitors leads to their death and disruption of the epithelial integrity. VANGL basolateral expansion does not affect apico-basal polarity but acts in the cells where Vangl is mislocalized by reducing Dishevelled and its downstream target ROCK. This reduction in ROCK activity culminates in progenitor cell egression, death, and eventually pancreatic hypoplasia. Thus, precise spatiotemporal modulation of VANGL-dependent PCP signaling is crucial for proper pancreatic morphogenesis.

Regulation of Wnt/PCP signaling through p97/VCP-KBTBD7-mediated Vangl ubiquitination and endoplasmic reticulum-associated degradation

The four-pass transmembrane proteins Vangl1 and Vangl2 are dedicated core components of Wnt/planar cell polarity (Wnt/PCP) signaling that critically regulate polarized cell behaviors in many morphological and physiological processes. Here, we found that the abundance of Vangl proteins is tightly controlled by the ubiquitin-proteasome system through endoplasmic reticulum-associated degradation (ERAD). The key ERAD component p97/VCP directly binds to Vangl at a highly conserved VCP-interacting motif and recruits the E3 ligase KBTBD7 via its UBA-UBX adaptors to promote Vangl ubiquitination and ERAD. We found that Wnt5a/CK1 prevents Vangl ubiquitination and ERAD by inducing Vangl phosphorylation, which facilitates Vangl export from the ER to the plasma membrane. We also provide in vivo evidence that KBTBD7 regulates convergent extension during zebrafish gastrulation and functions as a tumor suppressor in breast cancer by promoting Vangl degradation. Our findings reveal a previously unknown regulatory mechanism of Wnt/PCP signaling through the p97/VCP-KBTBD7-mediated ERAD pathway.

Structural basis of the human Scribble-Vangl2 association in health and disease

Scribble is a critical cell polarity regulator that has been shown to work as either an oncogene or tumor suppressor in a context dependent manner, and also impacts cell migration, tissue architecture and immunity. Mutations in Scribble lead to neural tube defects in mice and humans, which has been attributed to a loss of interaction with the planar cell polarity regulator Vangl2. We show that the Scribble PDZ domains 1, 2 and 3 are able to interact with the C-terminal PDZ binding motif of Vangl2 and have now determined crystal structures of these Scribble PDZ domains bound to the Vangl2 peptide. Mapping of mammalian neural tube defect mutations reveal that mutations located distal to the canonical PDZ domain ligand binding groove can not only ablate binding to Vangl2 but also disrupt binding to multiple other signaling regulators. Our findings suggest that PDZ-associated neural tube defect mutations in Scribble may not simply act in a Vangl2 dependent manner but as broad-spectrum loss of function mutants by disrupting the global Scribble-mediated interaction network.

The polarity protein Scrib limits atherosclerosis development in mice

AIMS

The protein Scrib (Scribble 1) is known to control apico-basal polarity in epithelial cells. The role of polarity proteins in the vascular system remains poorly characterized; however, we previously reported that Scrib maintains the endothelial phenotype and directed migration. On this basis, we hypothesized that Scrib has anti-atherosclerotic functions.

METHODS AND RESULTS

Tamoxifen-induced Scrib-knockout mice were crossed with ApoE-/- knockout mice and spontaneous atherosclerosis under high-fat diet (HFD), as well as accelerated atherosclerosis in response to partial carotid artery ligation and HFD, was induced. Deletion of Scrib resulted in increased atherosclerosis development in both models. Mechanistically, flow- as well as acetylcholine-induced endothelium-dependent relaxation and AKT phosphorylation was reduced by deletion of Scrib, whereas vascular permeability and leucocyte extravasation were increased after Scrib knockout. Scrib immune pull down in primary carotid endothelial cells and mass spectrometry identified Arhgef7 (Rho Guanine Nucleotide Exchange Factor 7, βPix) as interaction partner. Scrib or Arhgef7 down-regulation by siRNA reduced the endothelial barrier function in human umbilical vein endothelial cells. Gene expression analysis from murine samples and from human biobank material of carotid endarterectomies indicated that loss of Scrib resulted in endothelial dedifferentiation with a decreased expression of endothelial signature genes.

CONCLUSIONS

By maintaining a quiescent endothelial phenotype, the polarity protein Scrib elicits anti-atherosclerotic functions.

A mammalian Wnt5a-Ror2-Vangl2 axis controls the cytoskeleton and confers cellular properties required for alveologenesis

Alveolar formation increases the surface area for gas-exchange and is key to the physiological function of the lung. Alveolar epithelial cells, myofibroblasts and endothelial cells undergo coordinated morphogenesis to generate epithelial folds (secondary septa) to form alveoli. A mechanistic understanding of alveologenesis remains incomplete. We found that the planar cell polarity (PCP) pathway is required in alveolar epithelial cells and myofibroblasts for alveologenesis in mammals. Our studies uncovered a Wnt5a-Ror2-Vangl2 cascade that endows cellular properties and novel mechanisms of alveologenesis. This includes PDGF secretion from alveolar type I and type II cells, cell shape changes of type I cells and migration of myofibroblasts. All these cellular properties are conferred by changes in the cytoskeleton and represent a new facet of PCP function. These results extend our current model of PCP signaling from polarizing a field of epithelial cells to conferring new properties at subcellular levels to regulate collective cell behavior.

Consequences of mutations in the genes of the ER export machinery COPII in vertebrates

Coat protein complex II (COPII) plays an essential role in the export of cargo molecules such as secretory proteins, membrane proteins, and lipids from the endoplasmic reticulum (ER). In yeast, the COPII machinery is critical for cell viability as most COPII knockout mutants fail to survive. In mice and fish, homozygous knockout mutants of most COPII genes are embryonic lethal, reflecting the essentiality of the COPII machinery in the early stages of vertebrate development. In humans, COPII mutations, which are often hypomorphic, cause diseases having distinct clinical features. This is interesting as the fundamental cellular defect of these diseases, that is, failure of ER export, is similar. Analyses of humans and animals carrying COPII mutations have revealed clues to why a similar ER export defect can cause such different diseases. Previous reviews have focused mainly on the deficit of secretory or membrane proteins in the final destinations because of an ER export block. In this review, we also underscore the other consequence of the ER export block, namely ER stress triggered by the accumulation of cargo proteins in the ER.

Vangl2 acts at the interface between actin and N-cadherin to modulate mammalian neuronal outgrowth

Dynamic mechanical interactions between adhesion complexes and the cytoskeleton are essential for axon outgrowth and guidance. Whether planar cell polarity (PCP) proteins, which regulate cytoskeleton dynamics and appear necessary for some axon guidance, also mediate interactions with membrane adhesion is still unclear. Here we show that Vangl2 controls growth cone velocity by regulating the internal retrograde actin flow in an N-cadherin-dependent fashion. Single molecule tracking experiments show that the loss of Vangl2 decreased fast-diffusing N-cadherin membrane molecules and increased confined N-cadherin trajectories. Using optically manipulated N-cadherin-coated microspheres, we correlated this behavior to a stronger mechanical coupling of N-cadherin with the actin cytoskeleton. Lastly, we show that the spatial distribution of Vangl2 within the growth cone is selectively affected by an N-cadherin-coated substrate. Altogether, our data show that Vangl2 acts as a negative regulator of axonal outgrowth by regulating the strength of the molecular clutch between N-cadherin and the actin cytoskeleton.

The polarity protein VANG-1 antagonizes Wnt signaling by facilitating Frizzled endocytosis

Signaling that instructs the migration of neurons needs to be tightly regulated to ensure precise positioning of neurons and subsequent wiring of the neuronal circuits. Wnt-Frizzled signaling controls neuronal migration in metazoans, in addition to many other aspects of neural development. We show that Caenorhabditis elegans VANG-1, a membrane protein that acts in the planar cell polarity (PCP) pathway, antagonizes Wnt signaling by facilitating endocytosis of the Frizzled receptors. Mutations of vang-1 suppress migration defects of multiple classes of neurons in the Frizzled mutants, and overexpression of vang-1 causes neuronal migration defects similar to those of the Frizzled mutants. Our genetic experiments suggest that VANG-1 facilitates Frizzled endocytosis through β-arrestin2. Co-immunoprecipitation experiments indicate that Frizzled proteins and VANG-1 form a complex, and this physical interaction requires the Frizzled cysteine-rich domain. Our work reveals a novel mechanism mediated by the PCP protein VANG-1 that downregulates Wnt signaling through Frizzled endocytosis.

Regulation of spermatid polarity by the actin- and microtubule (MT)-based cytoskeletons

It is conceivable that spermatid apico-basal polarity and spermatid planar cell polarity (PCP) are utmost important to support spermatogenesis. The orderly arrangement of developing germ cells in particular spermatids during spermiogenesis are essential to obtain structural and nutrient supports from the fixed number of Sertoli cells across the limited space of seminiferous epithelium in the tubules following Sertoli cell differentiation by ∼17 day postpartum (dpp) in rodents and ∼12 years of age at puberty in humans. Yet few studies are found in the literature to investigate the role of these proteins to support spermatogenesis. Herein, we briefly summarize recent findings in the field, in particular emerging evidence that supports the concept that apico-basal polarity and PCP are conferred by the corresponding polarity proteins through their effects on the actin- and microtubule (MT)-based cytoskeletons. While much research is needed to bridge our gaps of understanding cell polarity, cytoskeletal function, and signaling proteins, a critical evaluation of some latest findings as summarized herein provides some important and also thought-provoking concepts to design better functional experiments to address this important, yet largely expored, research topic.