YAP-dependent Wnt5a induction in hypertrophic adipocytes restrains adiposity

DKK3 promotes adipogenic differentiation of stem cells by inhibiting Wnt/β-catenin signaling pathway related gene expression and mitochondrial autophagy function

Mesenchymal stem cells can differentiate into adipocyte precursor cells, and the balance of stem cell differentiation determines the quantity of adipocytes. Early-stage adipose tissue expression profiling revealed abnormal expression of DKK3 in the high-fat group. Moreover, DKK3 is enriched in the Wnt/β-catenin signaling pathway, and studies have shown that DKK3 can serve as a gene involved in early regulation of adipogenesis. Therefore, this study focuses on exploring how DKK3 regulates the molecular mechanism of adipocyte differentiation through the Wnt/β-catenin signaling pathway. In this experiment, the role of DKK3 in the differentiation of bone marrow mesenchymal stem cells into adipocyte precursors was validated using in vitro cultured chicken bone marrow mesenchymal stem cells. The results showed that overexpression of DKK3 led to a significant downregulation of Wnt/β-catenin signaling pathway-related marker gene expression (P < 0.05), a significant upregulation of adipogenic differentiation-related genes (P < 0.05), an increase in lipid droplet content, a significant increase in OD value (P < 0.05), a significant upregulation of mitochondrial oxidative respiratory-related marker gene expression (P < 0.05), and a significant downregulation of mitochondrial autophagy-related marker genes (P < 0.05). Conversely, the results were opposite after interfering with DKK3 gene expression. In this study, 4 SNP sites, including g.8419139, g.8419556, g.8419560, and g.8419598, were detected in the 7th exon of DKK3, among which the g.8419598 (C > T) site was significantly correlated with abdominal fat weight and abdominal fat rate in 100-day-old Ma Huang chickens (P < 0.001).

Atorvastatin exerts a preventive effect against steroid-induced necrosis of the femoral head by modulating Wnt5a release

Steroid-induced osteonecrosis of the femoral head (SONFH) is a prevalent form of osteonecrosis in young individuals. More efficacious clinical strategies must be used to prevent and treat this condition. One of the mechanisms through which SONFH operates is the disruption of normal differentiation in bone marrow adipocytes and osteoblasts due to prolonged and extensive use of glucocorticoids (GCs). In vitro, it was observed that atorvastatin (ATO) effectively suppressed the impact of dexamethasone (DEX) on bone marrow mesenchymal stem cells (BMSCs), specifically by augmenting their lipogenic differentiation while impeding their osteogenic differentiation. To investigate the underlying mechanisms further, we conducted transcriptome sequencing of BMSCs subjected to different treatments, leading to the identification of Wnt5a as a crucial gene regulated by ATO. The analyses showed that ATO exhibited the ability to enhance the expression of Wnt5a and modulate the MAPK pathway while regulating the Wnt canonical signaling pathway via the WNT5A/LRP5 pathway. Our experimental findings provide further evidence that the combined treatment of ATO and DEX effectively mitigates the effects of DEX, resulting in the upregulation of osteogenic genes (Runx2, Alpl, Tnfrsf11b, Ctnnb1, Col1a) and the downregulation of adipogenic genes (Pparg, Cebpb, Lpl), meanwhile leading to the upregulation of Wnt5a expression. So, this study offers valuable insights into the potential mechanism by which ATO can be utilized in the prevention of SONFH, thereby holding significant implications for the prevention and treatment of SONFH in clinical settings.

Hepatocyte-Specific Yap1 Knockout Maintained the Liver Homeostasis of Lipid Metabolism in Mice

Introduction

Yes-associated protein 1 (YAP1) is a crucial molecule in the Hippo pathway. The impact of hepatocyte-specific Yap1 knockout (Yap1 LKO) on hepatic lipid droplets (LD) and pePLIN2 in metabolic fatty liver has not been reported. This study aims to explore whether Yap1 LKO could offer a protective effect in a liver injury model.

Methods

Three-week-old Yap1 LKO and Yap1 Flox mice were given aristolochic acid I (AAI) combined carbon tetrachloride (CCL4) establish liver injury model. Eight-week-old Yap1 LKO and Yap1 Flox mice were fed with a high-fat diet for 18 weeks to establish obesity-related liver injury model. Further biochemical, histomorphological, immunohistochemical, and lipidomic analyses were performed on serum and liver tissues of these mice to elucidate the effects of hepatocyte-specific Yap1 knockout on hepatic lipid metabolism.

Results

Yap1 LKO reduced triglyceride (TG) content and PLIN2 expression level in the liver during the intervention of AAI combined CCl4. Moreover, Yap1 LKO improved lipid metabolism homeostasis in the liver by increasing the beneficial lipid molecules and reducing the harmful lipid molecules through lipidomics. Finally, Yap1 LKO reduced TG content in the serum and liver, hepatic vacuolar degeneration, and hepatic PLIN2 expression level in mice fed with a high-fat diet (HFD).

Conclusion

Yap1 LKO is protective in regulating liver and blood TG when induced with toxic substances AAI combined CCl4 and a high-fat diet.

Tailored Physicochemical Cues Direct Human Mesenchymal Stem Cell Differentiation through Epigenetic Regulation Using Colloidal Self-Assembled Patterns

The extracellular matrix (ECM) shapes the stem cell fate during differentiation by exerting relevant biophysical cues. However, the mechanism of stem cell fate decisions in response to ECM-backed complex biophysical cues has not been fully understood due to the lack of versatile ECMs. Here, we designed two versatile ECMs using colloidal self-assembly technology to probe the mechanisms of their effects on mechanotransduction and stem cell fate regulation. Binary colloidal crystals (BCC) with a hexagonally close-packed structure, composed of silica (5 μm) and polystyrene (0.4 μm) particles as well as a polydimethylsiloxane-embedded BCC (BCCP), were fabricated. They have defined surface chemistry, roughness, stiffness, ion release, and protein adsorption properties, which can modulate the cell adhesion, proliferation, and differentiation of human adipose-derived stem cells (hASCs). On the BCC, hASCs preferred osteogenesis at an early stage but showed a higher tendency toward adipogenesis at later stages. In contrast, the results of BCCP diverged from those of BCC, suggesting a unique regulation of ECM-dependent mechanotransduction. The BCC-mediated cell adhesion reduced the size of the focal adhesion complex, accompanying an ordered spatial organization and cytoskeletal rearrangement. This morphological restriction led to the modulation of mechanosensitive transcription factors, such as c-FOS, the enrichment of transcripts in specific signaling pathways such as PI3K/AKT, and the activation of the Hippo signaling pathway. Epigenetic analyses showed changes in histone modifications across different substrates, suggesting that chromatin remodeling participated in BCC-mediated mechanotransduction. This study demonstrates that BCCs are versatile artificial ECMs that can regulate human stem cells' fate through unique biological signaling, which is beneficial in biomaterial design and stem cell engineering.

Identifying G protein-coupled receptors involved in adipose tissue function using the innovative RNA-seq database FATTLAS

G protein-coupled receptors (GPCRs) modulate the function of adipose tissue (AT) in general and of adipocytes, specifically. Although it is well-established that GPCRs are widely expressed in AT, their repertoire as well as their regulation and function in (patho)physiological conditions (e.g., obesity) is not fully resolved. Here, we established FATTLAS, an interactive public database, for improved access and analysis of RNA-seq data of mouse and human AT. After extracting the GPCRome of non-obese and obese individuals, highly expressed and differentially regulated GPCRs were identified. Exemplarily, we describe four receptors (GPR146, MRGPRF, FZD5, PTGER2) and analyzed their functions in a (pre)adipocyte cell model. Besides all receptors being involved in adipogenesis, MRGPRF is essential for adipocyte viability and regulates cAMP levels, while GPR146 modulates adipocyte lipolysis via constitutive activation of Gi proteins. Taken together, by implementing and using FATTLAS we describe four hitherto unrecognized GPCRs associated with AT function and adipogenesis.

YAP/WNT5A/FZD4 axis regulates osteogenic differentiation of human periodontal ligament cells under cyclic stretch

OBJECTIVE

To verify the role of YAP/WNT5A/FZD4 axis in stretch-induced osteogenic differentiation of hPDLCs.

BACKGROUND

During orthodontic tooth movement, differentiation of human periodontal ligament cells (hPDLCs) at the tension side of the periodontal ligament mediates new bone formation. WNT5A promotes osteogenesis and its regulator Yes-associated protein (YAP) is responsive to mechanical stimulation in hPDLCs. However, the mechanisms of YAP and WNT5A in alveolar bone remodeling remain unclear.

METHODS

Cyclic stretch was applied to hPDLCs to mimic the orthodontic stretching force. Osteogenic differentiation was determined by alkaline phosphatase (ALP) activity, Alizarin Red staining, qRT-PCR and western blotting. To detect activation of YAP and expression of WNT5A and its receptor Frizzled-4 (FZD4), western blotting, immunofluorescence, qRT-PCR and ELISA were performed. Verteporfin, Lats-IN-1, small interfering RNAs and recombinant protein were used to explore the relationship of YAP, WNT5A and FZD4, and the effect of their relationship on stretch-induced osteogenesis of hPDLCs.

RESULTS

WNT5A, FZD4 and nuclear localization of YAP were upregulated by cyclic stretch. YAP positively regulated WNT5A and FZD4 expression and osteogenic differentiation of hPDLCs under cyclic stretch by YAP inhibition or activation assay. Knockdown of WNT5A and FZD4 attenuated YAP-induced and stretch-induced osteogenic differentiation. Recombinant WNT5A rescued the suppressed osteogenic differentiation by YAP inhibitor in hPDLCs, whereas knockdown of FZD4 weakened the effect of WNT5A and amplified the suppression.

CONCLUSIONS

WNT5A/FZD4 could be positively regulated by YAP and the YAP/WNT5A/FZD4 axis mediated osteogenic differentiation of hPDLCs under cyclic stretch. This study provided further insight into the biological mechanism of orthodontic tooth movement.

A Wrong Fate Decision in Adipose Stem Cells upon Obesity

Progress has been made in identifying stem cell aging as a pathological manifestation of a variety of diseases, including obesity. Adipose stem cells (ASCs) play a core role in adipocyte turnover, which maintains tissue homeostasis. Given aberrant lineage determination as a feature of stem cell aging, failure in adipogenesis is a culprit of adipose hypertrophy, resulting in adiposopathy and related complications. In this review, we elucidate how ASC fails in entering adipogenic lineage, with a specific focus on extracellular signaling pathways, epigenetic drift, metabolic reprogramming, and mechanical stretch. Nonetheless, such detrimental alternations can be reversed by guiding ASCs towards adipogenesis. Considering the pathological role of ASC aging in obesity, targeting adipogenesis as an anti-obesity treatment will be a key area of future research, and a strategy to rejuvenate tissue stem cell will be capable of alleviating metabolic syndrome.

Adipose Tissue Wasting as a Determinant of Pancreatic Cancer-Related Cachexia

Simple Summary

Pancreatic cancer (PC) is one of the deadliest cancers in the US. The poor prognosis of PC is related to diagnostic delay and the presence of unintended weight loss (cachexia) that commonly presents in PC patients even before diagnosis. However, the current understanding of how PC mediates cachexia is limited, and there are few treatments clinically available for cachexia. Based on the current literature, we demonstrate that PC-related cachexia primarily results from the wasting of adipose tissue, once thought to be merely a storage depot but now appreciated as an instrumental metabolic organ in the body. In addition, poor survival in PC patients was found to be associated with adipose tissue loss at diagnosis and during treatment. Therefore, identifying potential mediators and molecular mechanisms underlying adipose tissue loss would promise to pave the way for the development of effective interventions for PC-related cachexia

Abstract

Pancreatic cancer (PC) is the third leading cause of cancer-related death in the US, and its 5-year survival rate is approximately 10%. The low survival rates largely stem from diagnostic delay and the presence of significant adipose tissue and muscle wasting, commonly referred to as cachexia. Cachexia is present in nearly 80% of PC patients and is a key cause of poor response to treatment and about 20% of death in PC patients. However, there are few clinical interventions proven to be effective against PC-related cachexia. Different cancer types feature distinct secretome profiles and functional characteristics which would lead to cachexia development differently. Therefore, here we discuss affected tissues and potential mechanisms leading to cachexia in PC. We postulate that the most affected tissue during the development of PC-related cachexia is adipose tissue, historically and still thought to be just an inert repository for excess energy in relation to cancer-related cachexia. Adipose tissue loss is considerably greater than muscle loss in quantity and shows a correlation with poor survival in PC patients. Moreover, we suggest that PC mediates adipose atrophy by accelerating adipocyte lipid turnover and fibroblast infiltration.