Wnt Binding Affinity Prediction for Putative Frizzled-Type Cysteine-Rich Domains

A positive correlation of serum SFRP1 levels with the risk of developing type 2 diabetes mellitus: a case-control study

OBJECTIVE

Secreted frizzled-related protein 1 (SFRP1) is an adipokine whose production is significantly altered in metabolic disorders. Considering the relationship between dysfunction of Wnt/β-catenin signaling and metabolic disorders as well as the inhibitory effects of SFRP1 on this signaling pathway, the present work aimed to investigate the correlation between serum SFRP1 levels and type 2 diabetes mellitus (T2DM) and its developing risk factors for the first time.

METHODS

This case-control study measured serum levels of SFRP1, tumor necrosis factor (TNF)-α, interleukin (IL)-6, adiponectin, and fasting insulin using enzyme-linked immunosorbent assay kits in 80 T2DM patients and 80 healthy individuals. Biochemical parameters were determined using the AutoAnalyzer instrument.

RESULTS

The T2DM group had higher levels of SFRP1 compared with the controls (146.8100 ± 43.61416 vs 81.9531 ± 32.78545 pg/mL; P < .001). There was a positive correlation between SFRP1 and insulin (r = 0.327, P = .003), TNF-α (r = 0.420, P < .001) as well as homeostatic model assessment for insulin resistance (r = 0.328, P = .003) in the T2DM group. In addition, 10-unit changes in SFRP1 levels showed the risk of T2DM in both the unadjusted (odds ratio [OR] [95% CI] = 1.564 [1.359-1.800]) and adjusted models accounting for age, gender, and body mass index (OR [95% CI] = 1.564 [1.361-1.799]; P < .001). A cut-off value of SFRP1 (105.83 pg/mL) was identified to distinguish between the T2DM patients and the healthy subjects, with sensitivity of 75.0% and specificity of 80.0%.

CONCLUSION

According to our research, there was a significant and positive link between the amount of SFRP1 and the likelihood of developing T2DM as well as the related factors like insulin resistance index and TNF-α. These results indicated that SFRP1 might have a potential role in the development of T2DM.

Compound heterozygous WNT10A missense variations exacerbated the tooth agenesis caused by hypohidrotic ectodermal dysplasia

BACKGROUND

The aim of this study was to analyse the differences in the phenotypes of missing teeth between a pair of brothers with hypohidrotic ectodermal dysplasia (HED) and to investigate the underlying mechanism by comparing the mutated gene loci between the brothers with whole-exome sequencing.

METHODS

The clinical data of the patients and their mother were collected, and genomic DNA was extracted from peripheral blood samples. By Whole-exome sequencing filtered for a minor allele frequency (MAF) ≤0.05 non-synonymous single-nucleotide variations and insertions/deletions variations in genes previously associated with tooth agenesis, and variations considered as potentially pathogenic were assessed by SIFT, Polyphen-2, CADD and ACMG. Sanger sequencing was performed to detect gene variations. The secondary and tertiary structures of the mutated proteins were predicted by PsiPred 4.0 and AlphaFold 2.

RESULTS

Both brothers were clinically diagnosed with HED, but the younger brother had more teeth than the elder brother. An EDA variation (c.878 T > G) was identified in both brothers. Additionally, compound heterozygous variations of WNT10A (c.511C > T and c.637G > A) were identified in the elder brother. Digenic variations in EDA (c.878 T > G) and WNT10A (c.511C > T and c.637G > A) in the same patient have not been reported previously. The secondary structure of the variant WNT10A protein showed changes in the number and position of α-helices and β-folds compared to the wild-type protein. The tertiary structure of the WNT10A variant and molecular simulation docking showed that the site and direction where WNT10A binds to FZD5 was changed.

CONCLUSIONS

Compound heterozygous WNT10A missense variations may exacerbate the number of missing teeth in HED caused by EDA variation.

Secreted frizzled-related proteins: A promising therapeutic target for cancer therapy through Wnt signaling inhibition

The Wnt signaling system is a critical pathway that regulates embryonic development and adult homeostasis. Secreted frizzled-related proteins (SFRPs) are extracellular inhibitors of Wnt signaling that act by binding directly to Wnt ligands or Frizzled receptors. SFRPs can act as anti-Wnt agents and suppress cancer growth by blocking the action of Wnt ligands. However, SFRPs are often silenced by promoter methylation in cancer cells, resulting in hyperactivation of the Wnt pathway. Epigenetic modifiers can reverse this silencing and restore SFRPs expression. Despite the potential of SFRPs as a therapeutic target, the effects of SFRPs on tumor development remain unclear. Therefore, a review of the expression of various members of the SFRPs family in different cancers and their potential as therapeutic targets is warranted. This review aims to summarize the current knowledge of SFRPs in cancer, focusing on their expression patterns and their potential as novel therapeutic targets.

Role of smoothened and sfrp genes in Eupentacta fraudatrix regeneration

The secreted frizzled-related proteins (sfrp) and smoothened (smo) genes and their possible role in the regeneration of internal organs in the holothurian Eupentacta fraudatrix were studied. In this species, two sfrp genes were identified: sfrp1/2/5, sfrp3/4 and one smo gene. Their expression was analysed during regeneration of the aquapharyngeal bulb (AB) and intestine, and these genes were knock down by RNA interference. It has been shown that the expression of these genes is extremely important for the formation of AB. In all animals subjected to knockdown, at 7 days after evisceration, a full-sized AB rudiment was not formed. As a result of sfrp1/2/5 knockdown, the process of extracellular matrix remodelling in AB is interrupted, that leading to clusters of dense connective tissue formation, which slows down cell migration. When sfrp3/4 is knockdown, the connective tissue of AB anlage is completely disrupted and its symmetry is broken. The effect of smo knockdown was expressed in a significant impairment of AB regeneration, when connections between ambulacras were not formed after evisceration. However, despite severe disturbances in AB regeneration, a normal-sized gut anlage developed in all cases, which suggests that the regeneration of the digestive tube and AB occur independently of each other.

SFRP2 Overexpression Induces an Osteoblast-like Phenotype in Prostate Cancer Cells

Prostate cancer bone metastasis is still one of the most fatal cancer diagnoses for men. Survival of the circulating prostate tumor cells and their adaptation strategy to survive in the bone niche is the key point to determining metastasis in early cancer stages. The promoter of SFRP2 gene, encoding a WNT signaling modulator, is hypermethylated in many cancer types including prostate cancer. Moreover, SFRP2 can positively regulate osteogenic differentiation in vitro and in vivo. Here, we showed SFRP2 overexpression in the prostate cancer cell line PC3 induces an epithelial mesenchymal transition (EMT), increases the attachment, and modifies the transcriptome towards an osteoblast-like phenotype (osteomimicry) in a collagen 1-dependent manner. Our data reflect a novel molecular mechanism concerning how metastasizing prostate cancer cells might increase their chance to survive within bone tissue.

Functional role of the Frizzled linker domain in the Wnt signaling pathway

The Wnt signaling pathway plays a critical role in the developmental and physiological processes of metazoans. We previously reported that the Frizzled4 (FZD4) linker domain plays an important role in Norrin binding and signaling. However, the question remains whether the FZD linker contributes to Wnt signaling in general. Here, we show that the FZD linker is involved in Wnt binding and affects downstream Wnt signaling. A FZD4 chimera, in which the linker was swapped with that of the non-canonical receptor FZD6, impairs the binding with WNT3A and suppresses the recruitment of LRP6 and Disheveled, resulting in reduced canonical signaling. A similar effect was observed for non-canonical signaling. A FZD6 chimera containing the FZD1 linker showed reduced WNT5A binding and impaired signaling in ERK, JNK, and AKT mediated pathways. Altogether, our results suggest that the FZD linker plays an important role in specific Wnt binding and intracellular Wnt signaling.

Novel Biomolecules in the Pathogenesis of Gestational Diabetes Mellitus 2.0

Gestational diabetes mellitus (GDM) has become a major public health problem and one of the most discussed issues in modern obstetrics. GDM is associated with serious adverse perinatal outcomes and long-term health consequences for both the mother and child. Currently, the importance and purposefulness of finding a biopredictor that will enable the identification of women with an increased risk of developing GDM as early as the beginning of pregnancy are highly emphasized. Both “older” molecules, such as adiponectin and leptin, and “newer” adipokines, including fatty acid-binding protein 4 (FABP4), have proven to be of pathophysiological importance in GDM. Therefore, in our previous review, we presented 13 novel biomolecules, i.e., galectins, growth differentiation factor-15, chemerin, omentin-1, osteocalcin, resistin, visfatin, vaspin, irisin, apelin, FABP4, fibroblast growth factor 21, and lipocalin-2. The purpose of this review is to present the potential and importance of another nine lesser known molecules in the pathogenesis of GDM, i.e., 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), angiopoietin-like protein-8 (ANGPTL-8), nesfatin-1, afamin, adropin, fetuin-A, zonulin, secreted frizzled-related proteins (SFRPs), and amylin. It seems that two of them, fetuin-A and zonulin in high serum levels, may be applied as biopredictors of GDM.

Wnt Pathway Extracellular Components and Their Essential Roles in Bone Homeostasis

The Wnt pathway is involved in several processes essential for bone development and homeostasis. For proper functioning, the Wnt pathway is tightly regulated by numerous extracellular elements that act by both activating and inhibiting the pathway at different moments. This review aims to describe, summarize and update the findings regarding the extracellular modulators of the Wnt pathway, including co-receptors, ligands and inhibitors, in relation to bone homeostasis, with an emphasis on the animal models generated, the diseases associated with each gene and the bone processes in which each member is involved. The precise knowledge of all these elements will help us to identify possible targets that can be used as a therapeutic target for the treatment of bone diseases such as osteoporosis.

The structural biology of canonical Wnt signalling

The Wnt signalling pathways are of great importance in embryonic development and oncogenesis. Canonical and non-canonical Wnt signalling pathways are known, with the canonical (or β-catenin dependent) pathway being perhaps the best studied of these. While structural knowledge of proteins and interactions involved in canonical Wnt signalling has accumulated over the past 20 years, the pace of discovery has increased in recent years, with the structures of several key proteins and assemblies in the pathway being released. In this review, we provide a brief overview of canonical Wnt signalling, followed by a comprehensive overview of currently available X-ray, NMR and cryoEM data elaborating the structures of proteins and interactions involved in canonical Wnt signalling. While the volume of structures available is considerable, numerous gaps in knowledge remain, particularly a comprehensive understanding of the assembly of large multiprotein complexes mediating key aspects of pathway, as well as understanding the structure and activation of membrane receptors in the pathway. Nonetheless, the presently available data affords considerable opportunities for structure-based drug design efforts targeting canonical Wnt signalling.

Quantitative Profiling of WNT-3A Binding to All Human Frizzled Paralogues in HEK293 Cells by NanoBiT/BRET Assessments

The WNT signaling system governs critical processes during embryonic development and tissue homeostasis, and its dysfunction can lead to cancer. Details concerning selectivity and differences in relative binding affinities of 19 mammalian WNTs to the cysteine-rich domain (CRD) of their receptors—the ten mammalian Frizzleds (FZDs)—remain unclear. Here, we used eGFP-tagged mouse WNT-3A for a systematic analysis of WNT interaction with every human FZD paralogue in HEK293A cells. Employing HiBiT-tagged full-length FZDs, we studied eGFP-WNT-3A binding kinetics, saturation binding, and competition binding with commercially available WNTs in live HEK293A cells using a NanoBiT/BRET-based assay. Further, we generated receptor chimeras to dissect the contribution of the transmembrane core to WNT-CRD binding. Our data pinpoint distinct WNT-FZD selectivity and shed light on the complex WNT-FZD binding mechanism. The methodological development described herein reveals yet unappreciated details of the complexity of WNT signaling and WNT-FZD interactions, providing further details with respect to WNT-FZD selectivity.

Secreted Frizzled Related Proteins in Cardiovascular and Metabolic Diseases

Abnormal gene expression and secreted protein levels are accompanied by extensive pathological changes. Secreted frizzled related protein (SFRP) family members are antagonistic inhibitors of the Wnt signaling pathway, and they were recently found to be involved in the pathogenesis of a variety of metabolic diseases, which has led to extensive interest in SFRPs. Previous reports highlighted the importance of SFRPs in lipid metabolism, obesity, type 2 diabetes mellitus and cardiovascular diseases. In this review, we provide a detailed introduction of SFRPs, including their structural characteristics, receptors, inhibitors, signaling pathways and metabolic disease impacts. In addition to summarizing the pathologies and potential molecular mechanisms associated with SFRPs, this review further suggests the potential future use of SFRPs as disease biomarkers therapeutic targets.

Activation barriers in Class F G protein-coupled receptors revealed by umbrella sampling simulations

The Class F G protein-coupled receptors (GPCRs) include Smoothened and the ten Frizzled receptors, which are major cell membrane receptors in the Hedgehog and Wnt signalling pathways respectively and of enormous interest in embryonic development and as therapeutic targets in cancer. Recent crystal structures of Smoothened provide the opportunity to investigate the structural biology of Class F GPCRs in more detail, in turn, informing the development of therapeutics. A key question in this area is how one receptor may trigger distinct pathways - particularly relevant for Wnt signalling, in which signals may be transduced from a Frizzled via Dishevelled or G proteins, depending on the context. In this study, we employ adiabatic biased molecular dynamics and umbrella sampling to investigate the activation of Smoothened and Frizzled-7 in both the native state and bound to endogenous ligands, as well as how the clinically used Smoothened antagonist vismodegib alters this signalling. The results highlight key energetic barriers in the activation of these receptors, and the molecular features of the receptors mediating these barriers, demonstrating our approach as a robust means of investigating signalling through these receptors.

Functional Effects of WNT10A Rare Variants Associated with Tooth Agenesis

Mutations in WNT10A have frequently been reported as etiologic for tooth agenesis (TA). However, the effects of WNT10A variation on gene/protein function and contribution to TA phenotypes remain poorly understood. Here, we performed bioinformatic and functional characterization analysis of WNT10A variants. In silico prediction of variant function was performed with VIPUR for all WNT10A missense variants reported in the Exome Aggregation Consortium database. Functional characterization experiments were then performed for selected WNT10A variants previously associated with TA. Expression vectors for wild-type and mutant WNT10A were made and transfected into stem cells from human exfoliated deciduous teeth (SHED) for evaluation of gene/protein function, WNT signaling activity, and effects on expression of relevant genes. While 75% of WNT10A variants were predicted neutral, most of the TA-associated variants received deleterious scores by potentially destabilizing or preventing the disulfide bond formation required for proper protein function. WNT signaling was significantly decreased with 8 of 13 variants tested, whereas wild-type-like activity was retained with 4 of 13 variants. WNT10A-mutant cells (T357I, R360C, and R379C mutants) showed reduced or impaired binding affinity to FZD5, suggesting a potential mechanism for the decreased WNT signaling. Mutant cells also had decreased WNT10A protein expression in comparison to wild-type cells. mRNA expression of PAX9, MSX1, AXIN2, and RUNX2 (known tooth development genes) was perturbed in mutant cells and quite significantly for PAX9 and RUNX2. Transcriptome analysis of wild-type and T357I-mutant cells identified 36 differentially expressed genes (26 downregulated, 10 upregulated) involved in skeletal system development and morphogenesis and pattern specification. WNT10A variants deemed pathogenic for TA likely affect protein folding and/or stabilization, leading to decreased WNT signaling and concomitant dysregulated expression of relevant genes. These findings may allow for improved interpretation of TA phenotypes upon clinical diagnosis while providing important insights toward the development of future tooth replacement therapies.