Expression Of Wnt Signaling Components Research Articles

A Spatial Atlas of Wnt Receptors in Adult Mouse Liver

Hepatic zonation is critical for most metabolic functions in liver. Wnt signaling plays an important role in establishing and maintaining liver zonation. Yet, the anatomic expression of Wnt signaling components, especially all 10 Frizzled (Fzd) receptors, has not been characterized in adult liver. To address this, the spatial expression of Fzd receptors was quantitatively mapped in adult mouse liver via multiplex fluorescent in situ hybridization. Although all 10 Fzd receptors were expressed within a metabolic unit, Fzd receptors 1, 4, and 6 were the highest expressed. Although most Wnt signaling occurs in zone 3, expression of most Fzd receptors was not zonated. In contrast, Fzd receptor 6 was preferentially expressed in zone 1. Wnt2 and Wnt9b expression was highly zonated and primarily found in zone 3. Therefore, the current results suggest that zonated Wnt/β-catenin signaling at baseline occurs primarily due to Wnt2 and Wnt9b rather than zonation of Fzd mRNA expression. Finally, the study showed that Fzd receptors and Wnts are not uniformly expressed by all hepatic cell types. Instead, there is broad distribution among both hepatocytes and nonparenchymal cells, including endothelial cells. Overall, this establishment of a definitive mRNA expression atlas, especially of Fzd receptors, opens the door to future functional characterization in healthy and diseased liver states.

Functional and molecular characterization of PD1+ tumor-infiltrating lymphocytes from lung cancer patients

ABSTRACT Antibody-mediated cancer immunotherapy targets inhibitory surface molecules, such as PD1, PD-L1, and CTLA-4, aiming to re-invigorate dysfunctional T cells. We purified and characterized tumor-infiltrating lymphocytes (TILs) and their patient-matched non-tumor counterparts from treatment-naïve NSCLC patient biopsies to evaluate the effect of PD1 expression on the functional and molecular profiles of tumor-resident T cells. We show that PD1+ CD8+ TILs have elevated expression of the transcriptional regulator ID3 and that the cytotoxic potential of CD8 T cells can be improved by knocking down ID3, defining it as a potential regulator of T cell effector function. PD1+ CD4+ memory TILs display transcriptional patterns consistent with both helper and regulator function, but can robustly facilitate B cell activation and expansion. Furthermore, we show that expanding ex vivo-prepared TILs in vitro broadly preserves their functionality with respect to tumor cell killing, B cell help, and TCR repertoire. Although purified PD1+ CD8+ TILs generally maintain an exhausted phenotype upon expansion in vitro, transcriptional analysis reveals a downregulation of markers of T-cell dysfunction, including the co-inhibitory molecules PD1 and CTLA-4 and transcription factors ID3, TOX and TOX2, while genes involved in cell cycle and DNA repair are upregulated. We find reduced expression of WNT signaling components to be a hallmark of PD1+ CD8+ exhausted T cells in vivo and in vitro and demonstrate that restoring WNT signaling, by pharmacological blockade of GSK3β, can improve effector function. These data unveil novel targets for tumor immunotherapy and have promising implications for the development of a personalized TIL-based cell therapy for lung cancer.

Wnt/β-Catenin-Dependent Transcription in Autism Spectrum Disorders.

Autism spectrum disorders (ASD) is a heterogeneous group of neurodevelopmental disorders characterized by synaptic dysfunction and defects in dendritic spine morphology. In the past decade, an extensive list of genes associated with ASD has been identified by genome-wide sequencing initiatives. Several of these genes functionally converge in the regulation of the Wnt/β-catenin signaling pathway, a conserved cascade essential for stem cell pluripotency and cell fate decisions during development. Here, we review current information regarding the transcriptional program of Wnt/β-catenin signaling in ASD. First, we discuss that Wnt/β-catenin gain and loss of function studies recapitulate brain developmental abnormalities associated with ASD. Second, transcriptomic approaches using patient-derived induced pluripotent stem cells (iPSC) cells, featuring mutations in high confidence ASD genes, reveal a significant dysregulation in the expression of Wnt signaling components. Finally, we focus on the activity of chromatin-remodeling proteins and transcription factors considered high confidence ASD genes, including CHD8, ARID1B, ADNP, and TBR1, that regulate Wnt/β-catenin-dependent transcriptional activity in multiple cell types, including pyramidal neurons, interneurons and oligodendrocytes, cells which are becoming increasingly relevant in the study of ASD. We conclude that the level of Wnt/β-catenin signaling activation could explain the high phenotypical heterogeneity of ASD and be instrumental in the development of new diagnostics tools and therapies.

WNT signaling in atrial fibrillation.

The Wnt signaling pathway regulates physiological processes such as cell proliferation and differentiation, cell fate decisions, and stem cell maintenance and, thus, plays essential roles in embryonic development, but also in adult tissue homeostasis and repair. The Wnt signaling pathway has been associated with heart development and repair and has been shown to be crucially involved in proliferation and differentiation of progenitor cells into cardiomyocytes. The investigation of the role of the Wnt signaling pathway and the regulation of its expression/activity in atrial fibrillation has only just begun. The present minireview (I) provides original data regarding the expression of Wnt signaling components in atrial tissue of patients with atrial fibrillation or sinus rhythm and (II) summarizes the current state of knowledge of the regulation of Wnt signaling components' expression/activity and the contribution of the various levels of the Wnt signal transduction pathway to the processes of the development, maintenance, and progression of atrial fibrillation.

CBMS-12 Pro renin receptor antibody regulates glioblastoma stemness

Objective: Glioblastoma multiforme (GBM) is characterized by a strong self-renewal potential and poor differentiated state. We previously reported that (pro)renin receptor (PRR) was a potential target for glioma therapy by silencing the gene of PRR. Here, we have developed the monoclonal antibody of PRR and examined their effects on GBM. Materials and methods: We performed immunohistochemical analysis to detect the protein expression of PRR and SOX-2 in human sample of 56 gliomas. We used human glioma cell lines (U251MG and U87MG) and glioma stem cell line (MGG23) in vitro study. PRR antibody was designed to target the extracellular domain of the PRR with the rat lymph node method. Expression of the Wnt signaling components and stem marker (SOX-2, Oct3/4) in human glioma cell lines and glioma stem cell line treated with PRR antibody were measured using Western blotting. The effects of PRR antibody on cell proliferation, sphere formation, apoptosis, invasion were also examined. Subcutaneous xenografts with U87MG were induced in nude mice. Results: PRR expression showed a positive correlation with SOX-2 expression in glioma samples. Treatment with PRR antibody significantly reduced expression of Wnt signaling components and stem marker. We observed that PRR antibody significantly reduced cell proliferation and decreased sphere formation. Furthermore, PRR antibody suppressed invasion and induced apoptosis. In a subcutaneous U87MG xenograft model, systemic administration of the PRR antibody significantly reduced the size of the tumor volume. Conclusion: PRR has important role for the maintenance of stem cells and contribute to stem cell proliferation. PRR antibody inhibits cell proliferation and cell invasion and induces apoptosis. Treatment with PRR antibody could be an attractive therapeutic strategy for GBM.

S858 SUZ12 INACTIVATION COOPERATES WITH JAK3 MUTANT SIGNALING TO DRIVE T‐ALL DEVELOPMENT

Background:The PRC2 complex, with core components EZH2, SUZ12 and EED, is responsible for writing the H3K27me3 histone mark that is associated with gene repression. Sequence data analysis of 419 T‐cell acute lymphoblastic leukemia (T‐ALL) cases demonstrated that 14.3% of the cases harbored mutations in EZH2 (7.2%), SUZ12 (6.2%) and/or EED (3.8%). A significant positive association was found between SUZ12 loss‐of function mutations and JAK3 activating mutations.Aims:The goals of our study were to assess whether SUZ12 inactivation cooperates with JAK3 mutations in driving T‐ALL development, and to unravel the mechanism of oncogenic cooperation.Methods:We applied CRISPR gene editing technology to mutate endogenous Suz12 in mouse cells. For cell culture experiments, we used primary pro‐T‐cells derived from Cas9 transgenic mice that were retrovirally transduced with an activating JAK3(M511I) mutant, a Suz12 guide RNA (Suz12gRNA) or the combination of both. To generate mouse models, we performed bone marrow transplantations with hematopoietic stem/progenitor cells from Cas9 transgenic mice that were transduced with JAK3(M511I), Suz12gRNA or both. These cells were injected in wild type recipient mice and leukemia development was followed. RNA‐seq, ATAC‐seq and ChIP‐seq was performed on leukemia cells. We performed a drug screen with 189 inhibitors targeting a variety of epigenetic factors and signaling molecules on the mouse leukemia cells ex vivo.Results:The combined expression of JAK3(M511I) with Suz12gRNA conferred IL7‐independent growth to ex vivo cultured pro‐T cells, whereas JAK3(M511I) or Suz12gRNA alone did not, indicating direct cooperation between mutant JAK3 signaling and Suz12 inactivation. Moreover, in mouse bone marrow transplant leukemia models, combined expression of JAK3(M511I) and Suz12gRNA resulted in accelerated leukemia development with a mean latency of 74 days, compared to JAK3(M511I) or Suz12gRNA alone which generated leukemias with longer latency (112 to 150 days, p < 0.001). JAK3(M511I)+Suz12gRNA leukemias were CD8+ or CD4+CD8+ T‐cell leukemias and were transplantable. Effective Suz12 gene editing was confirmed by sequence analysis, Western blotting and intracellular flow cytometry documenting very low Suz12 and H3K27me3 levels. Both in vitro and in vivo data thus showed that inactivation of Suz12 cooperates with JAK3(M511I). Integration of gene expression data with ChIP‐seq data for Suz12 and H3K27me3, revealed increased expression of Wnt signaling components and Wnt target genes, as well as activation of the PI3K‐AKT‐mTOR signaling pathway in the JAK3(M511I)+Suz12gRNA leukemia cells compared to JAK3(M511I) leukemia cells. In addition, a drug screen on JAK3(M511I)+Suz12gRNA leukemia cells revealed increased sensitivity for PI3K, mTOR and Wnt signaling inhibitors, which is in line with upregulation of Pik3cb, Akt3 and Wnt signaling genes detected by RNA‐seq and ChIP‐seq. Surprisingly, this pharmacological approach also uncovered an increased sensitivity of the JAK3(M511I)+Suz12gRNA leukemia cells to HDAC6 inhibitors compared to JAK3(M511I) leukemia cells.Summary/Conclusion:We have shown that Suz12 inactivation cooperates with JAK3 mutant signaling to drive T‐ALL through upregulation of Wnt and PI3K/mTOR pathways. Furthermore, we were also able to identify specific vulnerabilities of the JAK3/Suz12 mutant leukemia cells, as they showed increased sensitivity to Wnt, PI3K/mTOR and HDAC6 inhibitors.

Wnt Signaling Alterations in the Human Spinal Cord of Amyotrophic Lateral Sclerosis Cases: Spotlight on Fz2 and Wnt5a.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with no cure, and elucidation of the mechanisms mediating neuronal death in this neuropathology is crucial to develop effective treatments. It has recently been demonstrated in animal models that the Wnt family of proteins is involved in this neuropathology, although its potential involvement in case of humans is almost unknown. We analyzed the expression of Wnt signaling components in healthy and ALS human spinal cords by quantitative RT-PCR, and we found that most Wnt ligands, modulators, receptors, and co-receptors were expressed in healthy controls. Moreover, we observed clear alterations in the mRNA expression of different components of this family of proteins in human spinal cord tissue from ALS cases. Specifically, we detected a significant increase in the mRNA levels of Wnt3, Wnt4, Fz2, and Fz8, together with several non-significant increases in the mRNA expression of other genes such as Wnt2b, Wnt5a, Fz3, Lrp5, and sFRP3. Based on these observations and on previous reports of studies performed in animal models, we evaluated with immunohistochemistry the protein expression patterns of Fz2 and Fz5 receptors and their main ligand Wnt5a in control samples and ALS cases. No substantial changes were observed in Fz5 protein expression pattern in ALS samples. However, we detected an increase in the amount of Fz2+ astrocytes in the borderline between gray and white matter at the ventral horn in ALS samples. Finally, Wnt5a expression was observed in neurons and astrocytes in both control and ALS samples, although Wnt5a immunolabeling in astroglial cells was significantly increased in ALS spinal cords in the same region where changes in Fz2 were observed. Altogether, these observations strongly suggest that the Wnt family of proteins, and more specifically Fz2 and Wnt5a, might be involved in human ALS pathology.

Dynamics of WNT signaling components in the human ovary from development to adulthood.

WNT signaling has been shown to play a pivotal role in mammalian gonad development and sex differentiation; however, its role in the developing human ovary has not been investigated. We analyzed a quantitative mass spectrometry dataset to determine the expression of WNT signaling components between 47 and 137 days of development and in adult ovarian cortex tissue. WNT signaling was identified within the top ten canonical pathways of proteins detected at every developmental stage examined. We further examined the specific localization of WNT signaling components glycogen synthase kinase 3 (GSK3B), frizzled 2 (FZD2), and β-catenin (CTNNB1) within ovarian tissue. GSK3B was nearly ubiquitously expressed during fetal development, while FZD2 was specific to germ cell nests during early development. β-catenin exhibited translocation from primarily membrane bound during early ovarian development to cytoplasmic and nuclear staining specifically in early primordial follicles in the fetal ovary. This cytoplasmic and nuclear β-catenin persisted in primordial follicles in adult ovarian tissue, but returned to membrane-bound localization in secondary follicles. We conclude that WNT signaling components are expressed in the human ovary from early to mid-gestation and remain in the adult ovary, and observed evidence for canonical WNT signaling only in the oocytes of primordial follicles. Together, these data are indicative of a role for canonical WNT signaling via β-catenin nuclear translocation during human follicle formation and follicle maintenance.

Hepatology Basic Science

Hepatology Basic Science

NOX4 Deletion in Male Mice Exacerbates the Effect of Ethanol on Trabecular Bone and Osteoblastogenesis.

Chronic alcohol consumption increases bone resorption and decreases bone formation. A major component of ethanol (EtOH) pathology in bone is the generation of excess reactive oxygen species (ROS). The ROS-generating NADPH oxidase-4 (NOX4) is proposed to drive much of the EtOH-induced suppression of bone formation. Here, 13-week-old male wild-type (WT) and NOX4-/- mice were pair fed (PF) a high-fat (35%), Lieber-DeCarli liquid diet with or without EtOH at 30% of their total calories for 12 weeks. Micro-computed tomography analysis demonstrated significant decreases in trabecular bone volume/total volume (BV/TV) percentage and cortical thickness in WT, EtOH-fed mice compared with PF controls. EtOH-fed NOX4-/- mice also displayed decreased trabecular BV/TV and trabecular number compared with PF (P < 0.05). However, NOX4-/- mice were protected against EtOH-induced decreases in cortical thickness (P < 0.05) and decreases in collagen1 and osteocalcin mRNA expression in cortical bone (P < 0.05). In WT and NOX4-/- vertebral bone, EtOH suppressed expression of Wnt signaling components that promote osteoblast maturation. A role for NOX4 in EtOH inhibition of osteoblast differentiation was further demonstrated by protection against EtOH inhibition of osteoblastogenesis in ex vivo bone marrow cultures from NOX4-/-, but not p47phox-/- mice lacking active NADPH oxidase-2. However, bone marrow cultures from NOX4-/- mice formed fewer osteoblastic colonies compared with WT cultures (P < 0.05), suggesting a role for NOX4 in the maintenance of mesenchymal progenitor cell populations. These data suggest that NOX4 deletion is partially protective against EtOH effects on osteoblast differentiation, but may predispose bone to osteogenic impairments.

A Wnt/Calcium Signaling Cascade Regulates Neuronal Excitability and Trafficking of NMDARs

Wnt signaling controls multiple biological process, particularly the embryonic development of metazoans. Sustained expression of Wnt signaling components in the mature mammalian CNS and their apparent deregulation in certain neuropathologies suggest that it also plays a part beyond embryonic development to regulate normal brain function. Wedescribe a noncanonical Wnt/Ca2+ signaling cascade that regulates the electrophysiological intrinsic properties of rat neurons, resulting in sustained membrane depolarization and the mobilization of Ca2+ from internal stores. These effects require tyrosine kinase-like orphan receptor 2 (RoR2), activation of PLC, and voltage-gated Ca2+ channels. Activation of this signaling cascade then promotes surface expression of N-methyl-D-aspartate receptors (NMDARs) through a SNARE-dependent mechanism. This neuronal Wnt/Ca2+ signaling pathway represents a mechanism for Wnt ligands to regulate normal brain processes in the mature animal and provides a framework for understanding how alterations in this pathway may contribute to the etiology of psychiatric disorders where NMDARs are compromised.

Wnt Signaling Alteration in the Spinal Cord of Amyotrophic Lateral Sclerosis Transgenic Mice: Special Focus on Frizzled-5 Cellular Expression Pattern.

BackgroundAmyotrophic lateral sclerosis is a chronic neurodegenerative disease characterized by progressive paralysis due to degeneration of motor neurons by unknown causes. Recent evidence shows that Wnt signaling is involved in neurodegenerative processes, including Amyotrophic Lateral Sclerosis. However, to date, little is known regarding the expression of Wnt signaling components in this fatal condition. In the present study we used transgenic SOD1G93A mice to evaluate the expression of several Wnt signaling components, with special focus on Frizzled-5 cellular expression alteration along disease progression.FindingsBased on previous studies demonstrating the expression of Wnts and their transcriptional regulation during Amyotrophic lateral sclerosis development, we have analyzed the mRNA expression of several Wnt signaling components in the spinal cord of SOD1G93A transgenic mice at different stages of the disease by using real time quantitative PCR analysis. Strikingly, one of the molecules that seemed not to be altered at mRNA level, Frizzled-5, showed a clear up-regulation at late stages in neurons, as evidenced by immunofluorescence assays. Moreover, increased Frizzled-5 appears to correlate with a decrease in NeuN signal in these cells, suggesting a correlation between neuronal affectation and the increased expression of this receptor.ConclusionsOur data suggest the involvement of Wnt signaling pathways in the pathophysiology of Amyotrophic Lateral Sclerosis and, more specifically, the implication of Frizzled-5 receptor in the response of neuronal cells against neurodegeneration. Nevertheless, further experimental studies are needed to shed light on the specific role of Frizzled-5 and the emerging but increasing Wnt family of proteins research field as a potential target for this neuropathology.

Wnt signaling regulates the stemness of lung cancer stem cells and its inhibitors exert anticancer effect on lung cancer SPC-A1 cells.

Wnt signaling plays an important role in regulating the activity of cancer stem cells (CSCs) in a variety of cancers. In this study, we explored the role of Wnt signaling in the lung cancer stem cells (LCSCs). LCSCs were obtained by sphere culture, for which human lung adenocarcinoma cell line SPC-A1 was treated with IGF, EGF and FGF-10. The stemness of LCSCs was confirmed by immunofluorescence, and pathway analysis was performed by functional genome screening and RT-PCR. The relationship between the identified signaling pathway and the expression of the stemness genes was explored by agonist/antagonist assay. Moreover, the effects of different signaling molecule inhibitors on sphere formation, cell viability and colony formation were also analyzed. The results showed that LCSCs were successfully generated as they expressed pluripotent stem cell markers Nanog and Oct 4, and lung distal epithelial markers CCSP and SP-C, by which the phenotype characterization of stem cells can be confirmed. The involvement of Wnt pathway in LCSCs was identified by functional genome screening and verified by RT-PCR. The expression of Wnt signaling components was closely related to the expression of the Nanog and Oct 4. Furthermore, targeting Wnt signaling pathway by using different signaling molecule inhibitors can exert anticancer effects. In conclusion, Wnt signaling pathway is involved in the stemness regulation of LCSCs and might be considered as a potential therapeutic target in lung adenocarcinoma.

High-resolution molecular validation of self-renewal and spontaneous differentiation in clinical-grade adipose-tissue derived human mesenchymal stem cells.

Improving the effectiveness of adipose-tissue derived human mesenchymal stromal/stem cells (AMSCs) for skeletal therapies requires a detailed characterization of mechanisms supporting cell proliferation and multi-potency. We investigated the molecular phenotype of AMSCs that were either actively proliferating in platelet lysate or in a basal non-proliferative state. Flow cytometry combined with high-throughput RNA sequencing (RNASeq) and RT-qPCR analyses validate that AMSCs express classic mesenchymal cell surface markers (e.g., CD44, CD73/NT5E, CD90/THY1, and CD105/ENG). Expression of CD90 is selectively elevated at confluence. Self-renewing AMSCs express a standard cell cycle program that successively mediates DNA replication, chromatin packaging, cyto-architectural enlargement, and mitotic division. Confluent AMSCs preferentially express genes involved in extracellular matrix (ECM) formation and cellular communication. For example, cell cycle-related biomarkers (e.g., cyclins E2 and B2, transcription factor E2F1) and histone-related genes (e.g., H4, HINFP, NPAT) are elevated in proliferating AMSCs, while ECM genes are strongly upregulated (>10-fold) in quiescent AMSCs. AMSCs also express pluripotency genes (e.g., POU5F1, NANOG, KLF4) and early mesenchymal markers (e.g., NES, ACTA2) consistent with their multipotent phenotype. Strikingly, AMSCs modulate expression of WNT signaling components and switch production of WNT ligands (from WNT5A/WNT5B/WNT7B to WNT2/WNT2B), while upregulating WNT-related genes (WISP2, SFRP2, and SFRP4). Furthermore, post-proliferative AMSCs spontaneously express fibroblastic, osteogenic, chondrogenic, and adipogenic biomarkers when maintained in confluent cultures. Our findings validate the biological properties of self-renewing and multi-potent AMSCs by providing high-resolution quality control data that support their clinical versatility.

Involvement of CDX2 in the cross talk between TNF-α and Wnt signaling pathway in the colon cancer cell line Caco-2

Tumor necrosis factor-α (TNF-α) is highly upregulated in inflammation and reduces the expression of the intestinal transcription factor, Caudal-related homeobox transcription factor 2 (CDX2). Wnt/β-catenin signaling is critical for intestinal cell proliferation, but a decreased CDX2 expression has influence on the Wnt signaling-related genes and progression of colorectal cancer. Although several inflammatory signaling pathways, including TNF-α, have been reported to promote Wnt/β-catenin activity and development of cancer, the underlying molecular mechanisms remain unclear. The aim was to investigate the signaling pathways involved in the TNF-α-mediated downregulation of CDX2, and its influence on Wnt/β-catenin signaling components in colon cancer cells. The expression of TNF-α and CDX2 at the invasive front were evaluated by immunohistochemical staining and showed reduced CDX2-positive cells in tumor buddings in areas with TNF-α expression in the surrounding inflammatory cells. In vitro studies revealed that TNF-α treatment showed a dose-dependent decrease of CDX2 messenger RNA (mRNA) and protein expression in Caco-2 cells. Inhibition of nuclear factor-kappaB or p38 pathways showed that these are involved in the TNF-α-dependent downregulation of CDX2. Furthermore, TNF-α-mediated downregulation of CDX2 was found to significantly decrease the mRNA levels of adenomatous polyposis coli (APC), axis inhibition protein 2 (AXIN2) and glycogen synthase kinase-3 beta (GSK3β), whereas the mRNA levels of Wnt targets were significantly elevated in TNF-α-treated Caco-2 cells. These findings were associated with reduced binding of CDX2 to promoter or enhancer regions of APC, AXIN2 and GSK3β. In conclusion, it was found that TNF-α induces the expression of Wnt signaling components through a downregulation of the CDX2 expression that might have a tumor-promoting effect on colon cancer cells.

Gut Commensal Bacteria and Regional Wnt Gene Expression in the Proximal Versus Distal Colon

Regional expression of Wingless/Int (Wnt) genes plays a central role in regulating intestinal development and homeostasis. However, our knowledge of such regional Wnt proteins in the colon remains limited. To understand further the effect of Wnt signaling components in controlling intestinal epithelial homeostasis, we investigated whether the physiological heterogeneity of the proximal and distal colon can be explained by differential Wnt signaling. With the use of a Wnt signaling-specific PCR array, expression of 84 Wnt-mediated signal transduction genes was analyzed, and a differential signature of Wnt-related genes in the proximal versus distal murine colon was identified. Several Wnt agonists (Wnt5a, Wnt8b, and Wnt11), the Wnt receptor frizzled family receptor 3, and the Wnt inhibitory factor 1 were differentially expressed along the colon length.These Wnt signatures were associated with differential epithelial cell proliferation and migration in the proximal versus distal colon. Furthermore, reduced Wnt/β-catenin activity and decreased Wnt5a and Wnt11 expression were observed in mice lacking commensal bacteria, an effect that was reversed by conventionalization of germ-free mice. Interestingly, myeloid differentiation primary response gene 88 knockout mice showed decreased Wnt5a levels, indicating a role for Toll-like receptor signaling in regulating Wnt5a expression. Our results suggest that the morphological and physiological heterogeneity within the colon is in part facilitated by the differential expression of Wnt signaling components and influenced by colonization with bacteria.

Wnt Signaling is Altered by Spinal Cord Neuronal Dysfunction in Amyotrophic Lateral Sclerosis Transgenic Mice

Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease characterized by progressive degeneration of the motor neurons in the cortex, brainstem, and spinal cord. The etiology and mechanisms of selective motor neuron loss in ALS remain unknown. Wnt signaling is involved in neurodegenerative processes but little is known about the kinetic changes in Wnt signaling during ALS progression. In this study we used transcriptional microarray analysis to examine the expression of Wnt signaling components in the spinal cords of ALS transgenic SOD1(G93A) mice at different stages. We found that ALS onset led to the upregulation of Wnt signaling components and target genes involved in growth regulation and proliferation. We also determined the expression of Wnt inhibitory factor-1 (Wif1) and Wnt4 in the spinal cord of ALS transgenic mice at different stages by Western blot and immunofluorescence analysis. The protein levels of Wif1 and Wnt4 in the spinal cords of ALS transgenic mice were upregulated compared to those in wild-type mice. Moreover, the expression of Wif1 and Wnt4 in mature GFAP+ astrocytes was increased at the end stage of ALS. Our findings demonstrate that Wnt signaling is altered by spinal cord neuronal dysfunction in adult ALS transgenic mice, which provides new insight into ALS pathogenesis.

Regional Wnt signatures in the colon and the influence of commensal bacteria

Wnt signaling is a key regulator of intestinal epithelial homeostasis. Since the large intestine exhibits considerable morphological and functional heterogeneity along its length, we investigated whether this can be explained by local differences in Wnt signaling. Furthermore, we examined whether divergent Wnt signaling may be shaped by commensal bacteria. Using a Wnt PCR array, expression of 84 genes related to Wnt‐mediated signal transduction was analyzed. A differential signature of Wnt related genes in the proximal vs. distal murine colon was identified. Specifically, we observed that Wnt agonists Wnt5a, Wnt8b, and Wnt11, Wnt receptors Fzd3 and Lrp6, and a Wnt inhibitory factor Wif1 were differentially expressed along the colon length. These Wnt signatures were associated with differential epithelial cell proliferation and migration in the proximal vs. distal colon. Given the importance of luminal bacteria in controlling epithelial homeostasis, Wnt gene expression in colonic segments of mice raised in germ‐free conditions were analyzed. Altered expression of Wnt genes was identified in mice raised in germ‐free vs. specific pathogen free conditions. These results suggest that the morphological and physiological heterogeneity within the colon is in part facilitated by differential expression of Wnt signaling components and influenced by colonization with bacteria.

GSK3Beta and LEF1 in regenerating young skeletal muscle following downhill running

The role of Wnt signaling during skeletal muscle repair has been studied using artificial models of muscle injury. Downhill running (DHR) is a physiological muscle injury model that involves a systems approach and is ideal when investigating sources of muscle repair.PurposeThe objective of this study was to determine if DHR affects Wnt signaling.MethodsC57BL/J6 male mice (3 mo) were exposed to either DHR or normal cage activity. The gastrocnemius was excised at 1, 2, 3, 4, 5, or 6 days post‐DHR. Gene (qRT‐PCR) and protein (western blot) expression of Wnt signaling components and GSK3□ (total and active) were measured.ResultsMuscle injury increased from baseline 0.4% to 1.4% at 3D, and 5D, and to 2.2% at 6D post‐DHR. M‐Cadherin protein increased from baseline (20.1%) to 54.7% at 3D through 5D (67.2%) post‐DHR. Total GSK3β protein decreased from baseline to 2D (3 fold), 3D (6 fold), 4D (3 fold) and 6D (3 fold) post‐DHR. GSK3βpY216 protein decreased from baseline to 2D (2.2 fold), 3D (3.7 fold), 4D (1.8 fold) and 6D (2.2 fold) post‐DHR. LEF1 protein increased from baseline to 5D and 6D (5 fold) post‐DHR.ConclusionsIn this study, DHR induced Wnt signaling activation. This physiological model provides insight into the complex role of Wnt signaling in skeletal muscle regeneration, which could be clinically important in treating skeletal muscle dysfunctions.

Expression of Wnt Signaling Components during Xenopus Pronephros Development

BackgroundThe formation of the vertebrate kidney is tightly regulated and relies on multiple evolutionarily conserved inductive events. These are present in the complex metanephric kidney of higher vertebrates, but also in the more primitive pronephric kidney functional in the larval stages of amphibians and fish. Wnts have long been viewed as central in this process. Canonical β-Catenin-dependent Wnt signaling establishes kidney progenitors and non-canonical β-Catenin-independent Wnt signaling participate in the morphogenetic processes that form the highly sophisticated nephron structure. While some individual Wnt signaling components have been studied extensively in the kidney, the overall pathway has not yet been analyzed in depth.Methodology/Principal FindingsHere we report a detailed expression analysis of all Wnt ligands, receptors and several downstream Wnt effectors during pronephros development in Xenopus laevis using in situ hybridization. Out of 19 Wnt ligands, only three, Wnt4, Wnt9a and Wnt11, are specifically expressed in the pronephros. Others such as Wnt8a are present, but in a broader domain comprising adjacent tissues in addition to the kidney. The same paradigm is observed for the Wnt receptors and its downstream signaling components. Fzd1, Fzd4, Fzd6, Fzd7, Fzd8 as well as Celsr1 and Prickle1 show distinct expression domains in the pronephric kidney, whereas the non-traditional Wnt receptors, Ror2 and Ryk, as well as the majority of the effector molecules are rather ubiquitous. In addition to this spatial regulation, the timing of expression is also tightly regulated. In particular, non-canonical Wnt signaling seems to be restricted to later stages of pronephros development.Conclusion/SignificanceTogether these data suggest a complex cross talk between canonical and non-canonical Wnt signaling is required to establish a functional pronephric kidney.