Wnt/β-Catenin Inhibitor Dickkopf 1

Transient suppression of Wnt signaling in poor-quality buffalo oocytes improves their developmental competence

Introduction

One of the most evolutionary conserved communication systems, the Wnt signaling pathway is a major gene regulatory pathway that affects the developmental competence of oocytes and regulates most embryonic developmental processes. The present study was undertaken to modulate the canonical Wnt (Wingless/integration) signaling pathway in the poor-quality (colorless cytoplasm after Brilliant Cresyl Blue staining, BCB-) buffalo cumulus-oocyte complexes (COCs) to improve their in vitro maturation (IVM) and embryo production (IVEP) rates.

Methods

The expression of key Wnt pathway genes was initially assessed in the good (blue cytoplasm after Brilliant Cresyl Blue staining, BCB+) and poor quality (BCB-) buffalo COCs to establish a differential activity of the Wnt pathway. The BCB- COCs were supplemented with the Wnt pathway inhibitor, Dickkopf-related protein 1 (DKK1) and later subjected to IVM and IVEP along with the BCB+ and BCB- controls. The cumulus expansion index (CEI), rate of nuclear maturation (mean percentage of oocytes in the MII stage) and embryo production, and the expression of developmentally important genes were evaluated to assess the effect of Wnt pathway inhibition on the development competence of these poor-quality oocytes.

Results

The Wnt pathway genes exhibited a significantly higher expression (p < 0.05) in the poor-quality BCB- oocytes compared to the good-quality BCB+ oocytes during the early maturation stages. The supplementation of BCB- COCs with 100 ng/mL DKK1 effectively inhibited the expression of the key mediators of the Wnt pathway (β-catenin and dishevelled homolog 1, DVL1). DKK1 supplemented BCB- COCs exhibited significantly improved cytoplasmic and nuclear maturation indices, development rates and significantly elevated expression (p < 0.05) of genes implicated in germinal vesicle breakdown (GVBD) and embryonic genome activation (EGA) vis-à-vis BCB- control COCs.

Conclusion

These data indicate that inhibition of the Wnt pathway during the initial course of oocyte maturation can improve the development competence of poor-quality buffalo oocytes.

High mobility group box 1 and Dickkopf-related protein 1 as biomarkers of glucose toxicity, atherogenicity, and lower β cell function in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is associated with increased atherogenicity and inflammatory responses, which may be related to high mobility group box 1 (HMGB1) and Dickkopf-related protein 1 (DKK1). The role of HMGB1 and DKK1 in T2DM is examined in association with lipid and insulin profiles. Serum HMGB1 and DKK1 were measured in T2DM with and without hypertension and compared with controls. The results showed that HMGB1 and DKK1 are higher in T2DM irrespective of hypertension. A large part of the variance in the β-cell index and glucose toxicity was explained by the combined effects of HMGB1 and DKK1. In conclusion, both HMGB1 and DKK1 may contribute to increased atherogenicity in T2DM. Moreover, both biomarkers may cause more deficits in β-cell function and increase glucose toxicity leading to the development of more inflammation and diabetic complications. HMGB1 and the Wnt pathways are other drug targets in treating T2DM.

DKK1 Positively Correlates with Lung Function in COPD Patients and Reduces Airway Inflammation

Purpose

WNT/β-catenin signal pathway is a potential hope for lung tissue repair. We investigated the levels of Dickkopf‐1 (DKK1), an endogenous inhibitor of WNT/β-catenin signal pathway, in chronic obstructive pulmonary disease (COPD) patients and airway inflammation.

Patients and Methods

Collected the demographic and clinical characteristics of 36 healthy controls, 25 stable COPD patients and 10 acute exacerbation of COPD (AECOPD) patients, then performed pulmonary function and detected serum DKK1 levels. After over-expression of DKK1, detect the levels of DDK1, lipoprotein-related protein 6 (LRP6) and inflammatory factors in bronchial epithelial cells stimulated with cigarette smoke extract (CSE).

Results

Serum DKK1 were reduced in stable COPD patients compared to healthy controls (3866.72 ± 775.33 pg/mL vs 5317.61 ± 1317.20 pg/mL, p<0.0001), but there was no significant difference between stable and acutely exacerbated patients (3866.72 ± 775.33 pg/mL vs 3482.10 ± 841.25 pg/mL, p>0.05). DKK1 was positively correlated with FEV1 (r = 0.570, p<0.0001), FEV1/FVC (rho = 0.590, p<0.0001), FEV1/Pre (r = 0.517, p<0.0001). Multiple linear regression analysis also suggested that FEV1 levels were higher with increasing DKK1. In vitro, elevated IL-6, IL-8, TNF-α and decreased DKK1, LRP6 were found in Beas-2B cells after CSE treatments, and increased LRP6 and decreased inflammatory factors were found after overexpression of DKK1. Andrographolide restored the CSE-induced decrease in DKK1 and increase in IL-6 and IL-8.

Conclusion

DKK1 levels were decreased in COPD patients and positively correlated with lung function, overexpression of DKK1 and andrographolide attenuated airway cell inflammation, both suggesting a potential role in pathophysiology and providing a disease-specific biomarker pattern.

Wnt/β-catenin pathway proteins in end-stage renal disease

Aim: To delineate the association of end-stage renal disease (ESRD) and Wnt-proteins including the agonist R-spondin-1, the transducer β-catenin and the antagonists DKK1 and sclerostin. Materials & methods: Serum Wnt-pathway proteins levels were measured by ELISA in 60 ESRD patients and 30 normal controls. Results: DKK1 and sclerostin were significantly higher in ESRD than in controls, and β-catenin and the catenin + R-spondin-1/DKK1 + sclerostin ratio, reflecting the ratio of agonist and transducer on antagonists (AT/ANTA), were significantly lower in ESRD. Estimated glomerular filtration rate was significantly associated with DKK1 and sclerostin (inversely), β-catenin (positively) and the AT/ANTA ratio (r = 0.468, p < 0.001). Conclusion: Wnt/β-catenin pathway proteins show significant alterations in ESRD, indicating significantly increased levels of antagonists.

The novel target of esophageal squamous cell carcinoma: lncRNA GASL1 regulates cell migration, invasion and cell cycle stagnation by inactivating the Wnt3a/β-catenin signaling

Long non-coding RNA (lncRNA) Growth-Arrest Associated LncRNA 1 (GASL1) is a lncRNA with a suppressive role in glioma, prostate carcinoma and gastric carcinoma, whereas its involvement in esophageal cancer is unknown. In the present study, we used RT-qPCR to detect the expression of GASL1 in esophageal cancer cell carcinoma (ESCC) cell lines, and constructed the overexpression and interference plasmids of GASL1 and the interference plasmid of DKK1. CCK8 was used to detect the cell proliferation level, clone formation experiment was used to detect the cell clonal formation ability, flow cytometry was used to detect the cell cycle level, and wound healing and Transwell experiments were respectively used to detect the cell invasion and migration. The interference and overexpression plasmids of GASL1 were injected into mice subcutaneously for tumor-bearing experiment. The body weight, tumor growth curve, and tumor weight of mice were recorded, and western blot was used to detect the expression of proliferation-, invasion-, and migration-related proteins and the expression of Wnt3a/β-catenin signal-related proteins in tumor tissues. LncRNA GASL1 was down-regulated in ESCC cell lines, and GASL1 inhibited ESCC cell progression and regulated cell cycle arrest in ESCC cells. In vivo, GASL1 inhibited tumor growth. GASL1 decreased the protein levels of DDK1, Wnt3a, β-catenin, and c-MYC in ESCC cell lines. Interfering DKK1 activates Wnt3a/β--catenin signal to reverse the inhibitory effects of GASL1 on proliferation, cell cycle acceleration, invasion, and migration. In conclusion, lncRNA GASL1 regulates cell migration, invasion and cell cycle stagnation by inactivating the wnt/β-catenin signaling.

The Interplay of WNT and PPARγ Signaling in Vascular Calcification

Vascular calcification (VC), the ectopic deposition of calcium phosphate crystals in the vessel wall, is one of the primary contributors to cardiovascular death. The pathology of VC is determined by vascular topography, pre-existing diseases, and our genetic heritage. VC evolves from inflammation, mediated by macrophages, and from the osteochondrogenic transition of vascular smooth muscle cells (VSMC) in the atherosclerotic plaque. This pathologic transition partly resembles endochondral ossification, involving the chronologically ordered activation of the β-catenin-independent and -dependent Wingless and Int-1 (WNT) pathways and the termination of peroxisome proliferator-activated receptor γ (PPARγ) signal transduction. Several atherosclerotic plaque studies confirmed the differential activity of PPARγ and the WNT signaling pathways in VC. Notably, the actively regulated β-catenin-dependent and -independent WNT signals increase the osteochondrogenic transformation of VSMC through the up-regulation of the osteochondrogenic transcription factors SRY-box transcription factor 9 (SOX9) and runt-related transcription factor 2 (RUNX2). In addition, we have reported studies showing that WNT signaling pathways may be antagonized by PPARγ activation via the expression of different families of WNT inhibitors and through its direct interaction with β-catenin. In this review, we summarize the existing knowledge on WNT and PPARγ signaling and their interplay during the osteochondrogenic differentiation of VSMC in VC. Finally, we discuss knowledge gaps on this interplay and its possible clinical impact.

Dkk (Dickkopf) Proteins

Clinical and preclinical studies over the past 3 decades have uncovered a multitude of signaling pathways involved in the initiation and progression of atherosclerosis. From these studies, signaling by proteins of the Wnt family has recently emerged as an important player in the development of atherosclerosis. Wnt signaling is characterized by a large number of ligands, receptors, and coreceptors and can be regulated at many different levels. Among Wnt modulators, the evolutionary conserved Dkk (Dickkopf) proteins, and especially Dkk-1, the founding member of the family, are the best characterized. The role of Dkks in the pathophysiology of the arterial wall is only partially understood, but their involvement in atherosclerosis is becoming increasingly evident. This review introduces recent key findings on Dkk proteins and their functions in atherosclerosis and discusses the potential importance of modulating Dkk signaling as part of a novel, improved strategy for preventing and treating atherosclerosis-related diseases.

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