Genetic Screening of WNT4 and WNT5B in Two Populations with Deviating Bone Mineral Densities

Mutation analysis of WNT4 gene in SRY negative 46,XX DSD patients with Mullerian agenesis and/or gonadal dysgenesis- An Indian study

Developmental disruption of the Mullerian duct and gonads in females leads to Mullerian agenesis and gonadal dysgenesis, respectively. These two structural abnormalities are coming under the 46,XX DSD (Disorders of Sexual Development) classification, the majority of cases the aetiology remains elusive. Without the SRY gene, WNT4 plays a key role in female reproductive structure development. Since there are no studies that explored the involvement of the WNT4 gene in Indian 46,XX DSD patients, we analysed the role of WNT4 in Indian 46,XX DSD patients with Mullerian agenesis and/or Gonadal dysgenesis. In our study, we recruited 103 adolescent girls with primary amenorrhea. After the cytogenetic and SRY gene analysis, we included thirty-two 46,XX DSD patients with Mullerian agenesis and/or gonadal dysgenesis for WNT4 gene mutation analysis. PCR sequencing was performed for all the coding exons of the WNT4 gene. Bioinformatic tools like Mutation Taster, Human Splicing Finder, and miRDB were used. We observed single nucleotide variations in three patients. One patient showed a known synonymous polymorphism (c.861C > T; p.G287G, rs544988174). miRDB data revealed the absence of microRNA regulatory sites in this region. The other two cases carried a nucleotide substitution in intronic regions and did not affect the normal splicing mechanism. In conclusion, we could not find any indication about WNT4 involvement in the disease condition. In the future, WNT4 promoter analysis in these patients and molecular characterization of the WNT4 coding and promoter region in more patients are needed to link WNT4 variants with these structural abnormalities.

Mice Lacking Wnt9a or Wnt4 Are Prone to Develop Spontaneous Osteoarthritis With Age and Display Alteration in Either the Trabecular or Cortical Bone Compartment

Osteoarthritis (OA) is a common degenerative disease of the joint, with a complex multifactorial not yet fully understood etiology. Over the past years, the Wnt signaling pathway has been implicated in osteoarthritis. In a recent genomewide association study (GWAS), the chromosomal location on chromosome 1, linked to the Wnt3a-Wnt9a gene locus, was identified as the most significant locus associated with a thumb osteoarthritis endophenotype. Previously, it was shown that WNT9a is involved in maintaining synovial cell identity in the elbow joint during embryogenesis. Here, we report that the conditional loss of Wnt9a in the Prx1-Cre expressing limb mesenchyme or Prg4-CreER expressing cells predispositions the mice to develop spontaneous OA-like changes with age. In addition, the trabecular bone volume is altered in these mice. Similarly, mice with a conditional loss of Wnt4 in the limb mesenchyme are also more prone to develop spontaneously OA-like joint alterations with age. These mice display additional alterations in their cortical bone. The combined loss of Wnt9a and Wnt4 increased the likelihood of the mice developing osteoarthritis-like changes and enhanced disease severity in the affected mice. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Roles and action mechanisms of WNT4 in cell differentiation and human diseases: a review

WNT family member 4 (WNT4), which belongs to the conserved WNT protein family, plays an important role in the development and differentiation of many cell types during the embryonic development and adult homeostasis. Increasing evidence has shown that WNT4 is a special ligand that not only activates the β-catenin independent pathway but also acts on β-catenin signaling based on different cellular processes. This article is a summary of the current knowledge about the expression, regulation, and function of WNT4 ligands and their signal pathways in cell differentiation and human disease processes. WNT4 is a promoter in osteogenic differentiation in bone marrow stromal cells (BMSCs) by participating in bone homeostasis regulation in osteoporotic diseases. Non-canonical WNT4 signaling is necessary for metabolic maturation of pancreatic β-cell. WNT4 is also necessary for decidual cell differentiation and decidualization, which plays an important role in preeclampsia. WNT4 promotes neuronal differentiation of neural stem cell and dendritic cell (DC) into conventional type 1 DC (cDC1). Besides, WNT4 mediates myofibroblast differentiation in the skin, kidney, lung, and liver during scarring or fibrosis. On the negative side, WNT4 is highly expressed in cancer tissues, playing a pro-carcinogenic role in many cancer types. This review provides an overview of the progress in elucidating the role of WNT4 signaling pathway components in cell differentiation in adults, which may provide useful clues for the diagnosis, prevention, and therapy of human diseases.

Knockout of TLR4 promotes fracture healing by activating Wnt/β-catenin signaling pathway

OBJECTIVES

The aim of this study was to investigate the effect of Toll like receptor 4 (TLR4) on fracture healing.

METHODS

The open tibial fracture models in TLR4 knockout (TLR4^-/-) and wild type (WT) C57BL-6 J mice were established. The radiological examination, tartrate-resistant acid phosphatase (TRAP) staining, Micro-CT scan and biological torsion test were performed on 7, 14 and 21 days after operation. Enzyme Linked Immunosorbent Assay (ELISA) kit was used to detect the expression levels of tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β) and interleukin 6 (IL-6). Western blotting was used to detect the expression of β-catenin, Wingless-type MMTV integration site family, member 4 and 5B (Wnt4 and Wnt5B), proliferating cell nuclear antigen (PCNA) and bone morphogenetic protein-2 (BMP-2) of the callus tissue obtained from mice.

RESULTS

TLR4 knockout promoted fracture healing, reduced the number of osteoclasts, increased bone callus volume (BV) and callus mineralized volume fraction (BV/TV%) (P <  0.05), increased the maximum torque and torsional stiffness of callus (P <  0.05), reduced TNF-α, IL-1β and IL-6 expression (P <  0.01), and increased the expression levels of β-catenin, Wnt4, Wnt5B, PCNA and BMP-2 (P <  0.01).

CONCLUSION

TLR4 knockout reduced inflammatory and promoted fracture healing by activating Wnt/β-catenin signaling pathway.

A specific haplotype in potential miRNAs binding sites of secreted frizzled-related protein 1 (SFRP1) is associated with BMD variation in osteoporosis

PURPOSE

Osteoporosis is an important multifactorial disease which is largely influenced by Wnt signaling pathway. Considering regulatory single nucleotide polymorphisms in Wnt signaling pathway may pave the road of understanding the genetic basis of predisposition to osteoporosis. The aim of this study was to determine the possible association between variants of SFRP1 and WNT5b, and osteoporosis incidence risk.

METHODS

The study population comprised 186 osteoporotic patients and 118 normal subjects from Amirkola Health and Ageing Project. rs1127379 (c.1406A>G) and rs3242 (c.3132C>T) variants in 3'UTR of SFRP1 gene, and rs3803164 (c.236C>T) in 3'UTR and rs735890 (c.622-536A>G) in intron 4 of WNT5b gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Regression analyses were used to calculate the association of genotype frequencies with bone mineral density (BMD) and bone mineral content (BMC) values of participants. Bioinformatics algorithms were used to detect the effect of each SNP on the secondary structure of mRNA, and predict putative 3'UTR microRNA target sites and splicing sites changes by related SNPs.

RESULTS

WNT5b rs735890 was associated with lumbar spine BMD, BMC, and femoral neck BMC (P = 0.035, P = 0.007, and P = 0.038, respectively). WNT5b rs3803164, and SFRP1 rs3242 were significantly associated with lumbar spine BMD (P = 0.028 and P = 0.030, respectively). SFRP1 rs1127379 was associated with lumbar spine BMD in the male gender. Haplotype analysis showed a significant association of SFRP1 c.[1406A; 3132C] haplotype with lumbar spine BMD, and BMC (P = 0.019 and P = 0.030, respectively), and SFRP1 c.[1406G; 3132C] haplotype with lumbar spine BMC (P = 0.045). In silico analyses revealed that the G allele of SFRP1 rs1127379, and WNT5b rs3803164 appear as more possible target sites for many miRNAs.

CONCLUSIONS

This study is the first evidence of the association of WNT5b rs735890, and c.[1406A; 3132C] and c.[1406G; 3132C] haplotypes of SFRP1 with BMD variation in osteoporosis, probably by altering microRNA target sites, in elderly persons.