Cysteine-rich protein 61 regulates adipocyte differentiation from mesenchymal stem cells through mammalian target of rapamycin complex 1 and canonical Wnt signaling

Fibro-adipogenic progenitors in physiological adipogenesis and intermuscular adipose tissue remodeling

Excessive accumulation of intermuscular adipose tissue (IMAT) is a common pathological feature in various metabolic and health conditions and can cause muscle atrophy, reduced function, inflammation, insulin resistance, cardiovascular issues, and unhealthy aging. Although IMAT results from fat accumulation in muscle, the mechanisms underlying its onset, development, cellular components, and functions remain unclear. IMAT levels are influenced by several factors, such as changes in the tissue environment, muscle type and origin, extent and duration of trauma, and persistent activation of fibro-adipogenic progenitors (FAPs). FAPs are a diverse and transcriptionally heterogeneous population of stromal cells essential for tissue maintenance, neuromuscular stability, and tissue regeneration. However, in cases of chronic inflammation and pathological conditions, FAPs expand and differentiate into adipocytes, resulting in the development of abnormal and ectopic IMAT. This review discusses the role of FAPs in adipogenesis and how they remodel IMAT. It highlights evidence supporting FAPs and FAP-derived adipocytes as constituents of IMAT, emphasizing their significance in adipose tissue maintenance and development, as well as their involvement in metabolic disorders, chronic pathologies and diseases. We also investigated the intricate molecular pathways and cell interactions governing FAP behavior, adipogenesis, and IMAT accumulation in chronic diseases and muscle deconditioning. Finally, we hypothesize that impaired cellular metabolic flexibility in dysfunctional muscles impacts FAPs, leading to IMAT. A deeper understanding of the biology of IMAT accumulation and the mechanisms regulating FAP behavior and fate are essential for the development of new therapeutic strategies for several debilitating conditions.

miR‑30a‑5p induces the adipogenic differentiation of bone marrow mesenchymal stem cells by targeting FAM13A/Wnt/β‑catenin signaling in aplastic anemia

Aplastic anemia (AA) is a bone marrow failure syndrome with high morbidity and mortality. Bone marrow (BM)-mesenchymal stem cells (MSCs) are the main components of the BM microenvironment, and dysregulation of BM-MSC adipogenic differentiation is a pathologic hallmark of AA. MicroRNAs (miRNAs/miRs) are crucial regulators of multiple pathological processes such as AA. However, the role of miR-30a-5p in the modulation of BM-MSC adipogenic differentiation in AA remains unclear. The present study aimed to explore the effect of miR-30a-5p on AA BM-MSC adipogenic differentiation and the underlying mechanism. The levels of miR-30a-5p expression and family with sequence similarity 13, member A (FAM13A) mRNA expression in BM-MSCs were quantified using reverse transcription-quantitative (RT-q) PCR. The mRNA expression levels of adipogenesis-associated factors [fatty acid-binding protein 4 (FABP4), lipoprotein lipase (LPL), perilipin-1 (PLIN1), peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα)] were analyzed using RT-qPCR. Lipid droplet accumulation was evaluated using Oil Red O staining in BM-MSCs. The interaction between miR-30a-5p and the FAM13A 3′-untranslated region was identified by TargetScan, and a dual-luciferase reporter assay was used to confirm the interaction. The expression levels of FAM13A and Wnt/β-catenin pathway-related proteins were examined via western blotting. The results showed that miR-30a-5p expression levels were significantly elevated in BM-MSCs from patients with AA compared with those in control subjects (iron deficiency anemia). miR-30a-5p expression levels were also significantly increased in adipose-induced BM-MSCs in a time-dependent manner. miR-30a-5p significantly promoted AA BM-MSC adipogenic differentiation, and significantly enhanced the mRNA expression levels of FABP4, LPL, PLIN1, PPARγ and C/EBPα as well as lipid droplet accumulation. miR-30a-5p was also demonstrated to target FAM13A in AA BM-MSCs. FAM13A significantly reduced BM-MSC adipogenic differentiation by activating the Wnt/β-catenin signaling pathway. In conclusion, miR-30a-5p was demonstrated to serve a role in AA BM-MSC adipogenic differentiation by targeting the FAM13A/Wnt/β-catenin signaling pathway. These findings suggest that miR-30a-5p may be a therapeutic target for AA.

Cyr61 Alleviates Cholangitis by Inhibiting Cytotoxic Effects of CD8+ T Cells on Biliary Epithelial Cells

OBJECTIVE

Primary biliary cholangitis (PBC) is a chronic progressive cholestatic liver disease. In recent years, researchers have found that cysteine-rich angiogenic inducer 61 (Cyr61, also known as CCN1) has a potential role in reducing portal inflammation in patients with PBC. This study aimed to explore the relationship between Cyr61 and PBC to provide new ideas and an experimental basis for the clinical treatment of PBC.

METHODS

After induction of the overexpression of Cyr61 in a mouse model of PBC using recombinant adenovirus, hematoxylin and eosin staining and pathological scores were used to indicate intrahepatic inflammation and bile duct damage. Real-time PCR was used to detect changes in inflammation-related cytokines in the liver. To further study the mechanism, we assessed whether Cyr61 protects bile duct epithelial cells from cytotoxic effects.

RESULTS

Serum and hepatic Cyr61 levels were increased in the murine model of PBC. Overexpression of Cyr61 alleviated hepatic inflammation and bile duct injury in vivo. Cyr61 inhibited the cytotoxic effects of CD8⁺ T cells by acting on biliary epithelial cells (BECs) in vitro.

CONCLUSION

Our results provide novel insight into the pathogenesis of PBC and suggest that Cyr61 plays a dominant role in the cytotoxic effects on BECs in PBC. Consequently, therapeutic strategies targeting Cyr61 could be a potent therapy for PBC.

Diagnostic value of using exosome-derived cysteine-rich protein 61 as biomarkers for acute coronary syndrome

Acute coronary syndrome (ACS) is the main manifestation of cardiovascular disease and the primary cause of adult hospitalization in China. There is an urgent demand for novel biomarkers for the diagnosis of ACS. Although plasma cysteine-rich protein 61 (Cyr61) has been previously reported to be accurate for ACS diagnosis, the accuracy of exosomal Cyr61 in ACS diagnosis remains unknown. In the present study, the aim was to assess the potential of applying exosomal Cyr61 in ACS diagnosis and to explore the role of Cyr61 in vascular remodeling in vitro. The abundance of Cyr61 in plasma-derived exosomes from patients with unstable angina pectoris (UAP), acute myocardial infarction (AMI) patients in addition to those isolated from healthy individuals were detected using an ELISA kit. The association between exosomal Cyr61 levels and clinical characteristics of ACS patients was analyzed through χ² test, Fisher's exact test and Student's t-test. Receiver operating characteristic (ROC) curve analysis was used to determine the accuracy of using exosomal Cyr61 as a biomarker of ACS diagnosis. Furthermore, independent predictors of the existence of ACS were investigated through a multivariate analysis. Subsequently, the role of Cyr61 on vascular remodeling was evaluated in vascular smooth muscle cells (VSMCs) upon oxidized low-density lipoprotein (ox-LDL) treatment by performing Cyr61 knockdown, Cell Counting Kit-8, flow cytometry and Transwell assays. Exosomal Cyr61 expression was found to be significantly elevated in patients with ACS compared with that in healthy individuals. In addition, exosomal Cyr61 levels were associated with sex, family history of ACS and glucose levels. ROC curve analyzes revealed that exosomal Cyr61 expression could be used to differentiate patients with UAP, AMI and ACS from healthy individuals. Furthermore, exosomal Cyr61 levels were independently correlated with the existence of ACS. In vitro, Cyr61 expression was demonstrated to be significantly increased in VSMCs after ox-LDL exposure in a concentration- and time-dependent manner. Functionally, the elevated cell viability and migration of VSMCs induced by ox-LDL were partially but significantly inhibited by Cyr61 knockdown. By contrast, knocking down Cyr61 expression significantly elevated the apoptosis rate of VSMCs compared with that in the ox-LDL-treated group. In conclusion, data from the present study suggest that Cyr61 serve a regulatory role in vascular remodeling in vitro, where exosomal Cyr61 levels may represent a promising biomarker for ACS diagnosis.

Sparcl1 promotes nonalcoholic steatohepatitis progression in mice through upregulation of CCL2

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of chronic liver disease ranging from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH). However, the molecular mechanisms of NASH progression remain incompletely understood. White adipose tissue (WAT) has emerged as an important endocrine organ and contributes not only to the initial stage of NAFLD, but also to its severity. In the current study, through transcriptomic analysis we identified increased expression of Sparcl1, a secreted glycoprotein, in the WAT from NASH mice. Plasma Sparcl1 levels were similarly elevated and positively correlated with hepatic pathological features in NASH patients. Functional studies showed that both chronic injection of recombinant Sparcl1 protein and overexpression of Sparcl1 exaggerated hepatic inflammation and liver injury in mice. In contrast, genetic ablation of Sparcl1, knockdown of Sparcl1 in WAT, and treatment with a Sparcl1-neutralizing antibody dramatically alleviated diet-induced NASH pathogenesis. Mechanistically, Sparcl1 promoted the expression of C-C motif chemokine ligand 2 (CCL2) in hepatocytes through binding to Toll-like receptor 4 (TLR4) and activation of the NF-κB/p65 signaling pathway. Genetically or pharmacologically blocking the CCL2/CCR2 pathway attenuated the hepatic inflammatory response evoked by Sparcl1. Thus, our results demonstrated an important role for Sparcl1 in NASH progression, suggesting a potential target for therapeutic intervention.

Association between circulating follistatin-like-1 and metabolic syndrome in middle-aged and old population: A cross-sectional study

AIM

Follistatin-like-1 (FSTL-1) is considered to be a novel cytokine, and it is associated with metabolic diseases. However, it is necessary to investigate further the association of FSTL-1 with metabolic syndrome (MetS) and insulin resistance (IR). We performed a cross-sectional study to investigate the associated of circulating FSTL-1 with the MetS.

MATERIALS AND METHODS

A cross-sectional study was performed in 487 Chinese people, including 231 control subjects and 256 patients with MetS. Bioinformatics analysis was used to determine the protein and pathways associated with FSTL-1. The protein and protein interaction (PPI) network was constructed and analysed. Serum FSTL-1 concentrations were determined by an ELISA assay. The association of FSTL-1 with MetS components and IR was assessed.

RESULTS

Serum FSTL-1 levels were markedly higher in patients with newly diagnosed MetS than in controls (7.5 [5.6-9.2] vs 5.8 [5.0-7.7] μg/L, P < .01). According to bioinformatics analysis, the top high-degree genes were identified as the core genes, including SPARCL1, CYR61, LTBP1, IL-6, BMP2, BMP4, FBN1, FN1 CHRDL1 and FSTL-3. These genes are mainly enriched in pathways including TGF-ß, AGE-RAGE signalling pathway in diabetic complications, and Hippo signalling pathways; in basal cell carcinoma, cytokine-cytokine receptor interaction and in amoebic and Yersinia infections. Furthermore, serum FSTL-1 levels were positively associated with fasting plasma glucose (FPG), waist circumference (WC), blood pressure, triglyceride levels and visceral adiposity index (VAI). We found that serum FSTL-1 levels were markedly associated with MetS and IR by binary logistic regression analysis.

CONCLUSIONS

We conclude that FSTL-1 may be a novel cytokine related to MetS and IR.

Simvastatin Inhibits CYR61 Expression in Orbital Fibroblasts in Graves' Ophthalmopathy through the Regulation of FoxO3a Signaling

Graves' ophthalmopathy (GO), which is characterized by orbital tissue inflammation, expansion, and fibrosis, is the ocular manifestation in 25% to 50% of patients with Graves' disease. As the pathology of GO is driven by autoimmune inflammation, many proinflammatory cytokines/chemokines, including TNF-α, IL-1β, IL-6, and CCL20, are crucial in the pathogenesis of GO to activate the orbital fibroblasts. Cysteine-rich protein 61 (CYR61), which is known to regulate cell proliferation, adhesion, and migration, plays a proinflammatory role in the pathogenesis of many inflammatory diseases, such as rheumatoid arthritis. CYR61 was considered a potential biomarker of GO in recent studies. Statins, which are cholesterol-lowering drugs, were found to reduce the risk of GO, probably through their anti-inflammatory and immunomodulatory effects. In this study, we established a link between CYR61 and statins in the pathogenesis and potential treatment for GO. Firstly, our data showed the overexpression of CYR61 in the orbital tissue (n = 4) and serum specimens (n = 6) obtained from the patients with inactive GO. CYR61 could induce the production of IL-6 and CCL20 in cultured GO orbital fibroblasts. The expression of CYR61 in cultured GO orbital fibroblasts was upregulated via TNF-α stimulation. Secondly, we pretreated cultured GO orbital fibroblasts using simvastatin, a statin, followed by TNF-α stimulation. The data revealed that simvastatin could inhibit TNF-α-induced CYR61 expression by modulating the activity of transcription factor FoxO3a. Our results provided insights into some cellular mechanisms that may explain the possible protective effects of simvastatin against the development of GO.

Simvastatin downregulates adipogenesis in 3T3-L1 preadipocytes and orbital fibroblasts from Graves' ophthalmopathy patients

BACKGROUND

Smoking is a strong risk factor for the development of Graves' ophthalmopathy (GO). Immediate early genes (IEGs) are overexpressed in patients with active GO compared to healthy controls. The aim of this study was to study the effects of tobacco smoking and simvastatin on preadipocytes and orbital fibroblasts (OFs) in the adipogenic process.

METHODS

Cigarette smoke extract (CSE) was generated by a validated pump system. Mouse 3T3-L1 preadipocytes or OFs were exposed to 10% CSE with or without simvastatin. Gene expression was studied in preadipocytes and OFs exposed to CSE with or without simvastatin and compared to unexposed cells or cells treated with a differentiation cocktail.

RESULTS

In 3T3-L1 preadipocytes, Cyr61, Ptgs2, Egr1 and Zfp36 expression levels were two-fold higher in cells exposed to CSE than in unexposed cells. Simvastatin downregulated the expression of these genes (1.6-fold, 5.5-fold, 3.3-fold, 1.4-fold, respectively). CSE alone could not stimulate preadipocytes to differentiate. Scd1, Ppar-γ and adipogenesis were downregulated in simvastatin-treated preadipocytes compared to nontreated preadipocytes 18-, 35- and 1.7-fold, respectively. In OFs, similar effects of CSE were seen on the expression of CYR61 (1.4-fold) and PTGS2 (3-fold). Simvastatin downregulated adipogenesis, PPAR-γ (2-fold) and SCD (27-fold) expression in OFs.

CONCLUSION

CSE upregulated early adipogenic genes in both mouse 3T3-L1 preadipocytes and human OFs but did not by itself induce adipogenesis. Simvastatin inhibited the expression of both early and late adipogenic genes and adipogenesis in preadipocytes and human OFs. The effect of simvastatin should be investigated in a clinical trial of patients with GO.

Goodman C, E. Myers D, Hayes A, Duque G. Rapamycin Affects Palmitate-Induced Lipotoxicity in Osteoblasts by Modulating Apoptosis and Autophagy

Bone marrow fat infiltration is one of the hallmarks of aging and osteoporotic bones. Marrow adipocytes produce substantial amounts of palmitic acid (PA). PA is toxic to bone-forming osteoblasts in vitro, affecting their differentiation, function, and survival. Since rapamycin (RAP)-induced inhibition of target of rapamycin complex 1 (mTORC1) activates autophagy and prevents apoptosis, we hypothesized that RAP may preserve osteoblast viability and reduce PA-induced lipotoxicity. Normal human osteoblasts were incubated with RAP in the presence of a lipotoxic concentration of PA or vehicle for 24 and 48 hours. Expression of LC3 protein levels and the phosphorylation of the direct mTORC1 target p70S6K1-T389 were quantified by Western blot. Lysosomes and autophagosomes were studied using confocal fluorescence imaging, lysotracker, and live-cell imaging. RAP reduced PA-induced apoptosis. In addition, PA-induced autophagosome formation increased substantially over the time-course, an effect that was significantly regulated by the presence of RAP in the media. In addition, LC3I/II ratios were higher in PA-induced cells with RAP whereas p70S6K1-T389 were lower in PA and RAP together. In summary, this study highlights the role of the RAP-sensitive mTORC1 pathway in normal human osteoblasts under lipotoxic conditions. RAP-associated therapies could, potentially, be targeted for specific roles in osteoporosis and aging bone.