CTRP6 alleviates endometrial fibrosis by regulating Smad3 pathway in intrauterine adhesion†.

Intrauterine adhesion (IUA) is manifestations of endometrial fibrosis and excessive extracellular matrix deposition. C1q/tumor necrosis factor-related protein-6 (CTRP6) is a newly identified adiponectin paralog which has been reported to modulate the fibrosis process of several diseases; however, the endometrial fibrosis function of CTRP6 remains unknown. Our study aimed to assess the role of CTRP6 in endometrial fibrosis and further explore the underlying mechanism. Here, we found that the expression of CTRP6 was downregulated in the endometrial tissues of IUA. In vitro experiments demonstrated the reduced level of CTRP6 in facilitated transforming growth factor-ß1 (TGF-ß1)-induced human endometrial stromal cells (HESCs). In addition, CTRP6 inhibited the expression of α-smooth muscle actin (α-SMA) and collagen I in TGF-ß1-treated HESCs. Mechanistically, CTRP6 activated the AMP-activated protein kinase (AMPK) and protein kinase B (AKT) pathway in HESCs, and AMPK inhibitor (AraA) or PI3K inhibitor (LY294002) pretreatment abolished the protective effect of CTRP6 on TGF-ß1-induced fibrosis. CTRP6 markedly decreased TGF-ß1-induced Smad3 phosphorylation and nuclear translocation, and AMPK or AKT inhibition reversed these effects. Notably, CTRP6-overexpressing treatment alleviated the fibrosis of endometrium in vivo. Therefore, CTRP6 ameliorates endometrial fibrosis, among which AMPK and AKT are essential for the anti-fibrotic effect of CTRP6 via the Smad3 pathway. Taken together, CTRP6 may be a potential therapeutic target for the treatment of intrauterine adhesion.

Circulating levels of C1q/TNF-α-related protein 6 (CTRP6) in coronary artery disease and its correlation with inflammatory markers.

Introduction: Circulating levels of C1q/TNF-α-related protein 6 (CTRP6) is an adipokine that is involved in regulation of glucose and lipid metabolism, inflammation, and insulin sensitivity. However, the exact role of CTRP6 in metabolic processes remains unclear due to conflicting findings. To address current gap, we aimed to investigate the serum levels of CTRP6 in patients with coronary artery disease (CAD) and its association with inflammatory cytokines. Method: In this case-control study, the serum levels of CTRP6, interlukin-6 (IL-6), tumor necrosis factor- α (TNF-α), adiponectin, and fasting insulin were measured using enzyme-linked immunosorbent assay (ELISA) kits in a total of 176 participants, consisting of 88 CAD patients and 88 control subjects. Additionally, various anthropometric and biochemical measurements were measured and compared between cases and controls. Results: The present study found that serum levels of CTRP6 were significantly higher in the CAD group (561.3 ± 15.14) compared to the control group (429.3 ± 12.85, p < 0.001). After adjusting for age, sex, and body mass index (BMI), CTRP6 levels were found to be positively associated with the risk of CAD (p < 0.001). Correlation analysis in CAD subjects revealed a positive correlation between CTRP6 levels and BMI, systolic blood pressure (SBP), malondialdehyde (MDA), TNF-α, and IL-6, as well as a negative correlation with creatinine and total anti-oxidant capacity. Conclusion: The findings of this study provide novel evidence that elevated serum levels of CTRP6 are significantly associated with an increased risk of developing CAD. Moreover, our results indicate a correlation between CTRP6 and various risk factors for atherosclerosis. Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-024-01415-5.

Down regulation of C1q tumor necrosis factor-related protein 6 is associated with increased risk of breast cancer.

C1q tumor necrosis factor-related protein 6 (CTRP6), a member of the C1q tumor necrosis factor-related protein (CTRP) family, is reported to be associated with the progression of different malignancies, however, its expression levels and role in breast cancer (BC) are yet unknown. In this study, we investigated the levels of circulating CTRP6 in BC patients and evaluated its role as a potential diagnostic biomarker in BC patients. Then we investigated the effect of recombinant CTRP6 on cellular viability in MCF-7 cells along with its effects on the expression of inflammatory cytokines, interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α) in addition to the expression of vascular endothelial growth factor (VEGF) as a marker of angiogenesis. Our results showed decreased expression of circulating CTRP6 in BC patients with an inverse correlation between CTRP6 and IL-6, TNF-α and VEGF levels. Besides, Receiver operating characteristic (ROC) curve showed that the assessment of CTRP6 levels could be used to predict BC. Moreover, treatment of MCF-7 cells with recombinant CTRP6 protein reduced cellular viability and decreased IL-6, TNF-α and VEGF expression. In conclusion, these results provide new insights into the role of CTRP6 in BC pathogenesis and suggest its potential use as a novel diagnostic biomarker of BC.

Role of C1q/TNF-Related Protein 6 for the Evaluation of Coronary Heart Disease Associated with Type 2 Diabetes.

Objective: Coronary artery disease (CAD) and type 2 diabetes (T2DM) are closely associated with increased rate of death. C1q/TNF-related protein 6 (CTRP6) is a novel adipocytokine which plays an important role in glucose and lipid metabolism. Little is known about the function of CTRP6 in CAD and T2DM patients. Herein, we aimed to study the association of CTRP6 level with CAD and T2DM. Methods: This study included 51 CAD, 44 CAD+T2DM and 65 non-CAD+T2DM patients from Affiliated Aoyang Hospital of Jiangsu University. Serum CTRP6 concentrations were detected by ELISA. Multiple logistic regression was used to analyze the association of serum CTRP6 with CAD and T2DM. Results: Serum CTRP6 concentrations were significantly lower in CAD patients than controls. However, there is no significant statistical difference between CAD+T2DM patients and non-CAD+T2DM patients. Serum CTRP6 was negatively correlated with low-density lipoprotein cholesterol (LDL-C) (ρ=-0.2769, p=0.028) in controls. Serum CTRP6 was positively correlated with age (ρ=0.4121, p=0.0027), systolic blood pressure (SBP) (ρ=0.4012, p=0.0035), Creatinine (ρ=0.3295, p=0.0194), uric acid (UA) (ρ=0.3386, p=0.0162), and left ventricular end diastolic diameter (LVD) (ρ=0.4277, p=0.0042) and negatively correlated with ejection fraction (EF) (ρ=-0.3237, p=0.0342) in CAD patients. Serum CTRP6 was negatively correlated with high-density lipoprotein cholesterol (HDL-C) (ρ=-0.3164, p=0.0387) in CAD+T2DM patients. Multiple logistic regression showed that the decrease of CTRP6 was significantly related to the increased prevalence of CAD. What is more, CTRP6 increased prevalence of T2DM in CAD patients. Conclusion: Lower serum CTRP6 could be a risk factor of CAD. However, higher circulating CTRP6 associated with the increased prevalence of T2DM in CAD patients.

Characterizing the Dynamic Expression of C1q/TNF-α-Related Protein 6 (CTRP6) during Pregnancy in Humans and Mice with Gestational Diabetes Mellitus.

AIM: C1q/TNF-related protein 6 (CTRP6) is a novel adipokine involved in insulin resistance. Thus, we aim to investigate the expression profile of CTRP6 in the plasma, adipose tissue and placenta of GDM patients and mice. METHODS: Chinese Han pregnant women (GDM n = 9, control n = 10) with a scheduled caesarean section delivery were recruited. A number of high-fat diet (HFD) induced-pregnancy C57BL/6 mice were chosen as an animal model of GDM. Circulating levels of CTRP6 and adiponectin were examined by ELISA. CTRP6 expression in adipose tissue and placenta were detected by real-time qPCR and WB. RESULT: Plasma CTRP6 levels were decreased during the first and second trimesters in mice, as well as the second and third trimesters in patients, while they were increased at delivery in GDM patients and mice. Plasma CTRP6 levels were significantly correlated with WBC, systolic pressure, diastolic pressure and fasting blood glucose. Moreover, CTRP6 mRNA expression in the subcutaneous (sWAT) and omental white adipose tissue (oWAT), as well as in the placenta, was significantly higher in GDM human patients at cesarean delivery. Furthermore, the mRNA expression of Ctrp6 was increased in the sWAT and visceral WAT (vWAT), whilst decreased in the interscapular brown adipose tissue (iBAT), of GDM mice at cesarean delivery. CONCLUSION: Dynamically expressed CTRP6 may be served as a candidate target for treatment of GDM.

CTRP6 protects against ferroptosis to drive lung cancer progression and metastasis by destabilizing SOCS2 and augmenting the xCT/GPX4 pathway.

Lung cancer is a highly heterogeneous malignancy, and despite the rapid development of chemotherapy and radiotherapy, acquired drug resistance and tumor progression still occur. Thus, it is urgent to identify novel therapeutic targets. Our research aims to screen novel biomarkers associated with the prognosis of lung carcinoma patients and explore the potential regulatory mechanisms. We obtained RNA sequencing (RNA-seq) data of lung cancer patients from public databases. Clinical signature analysis, weighted gene coexpression network analysis (WGCNA) and the random forest algorithm showed that C1q/tumor necrosis factor-related protein-6 (CTRP6) is a core gene related to lung cancer prognosis, and it was determined to promote tumor proliferation and metastasis both in vivo and in vitro. Mechanistically, silencing CTRP6 was determined to promote xCT/GPX4-involved ferroptosis through functional assays related to lipid peroxidation, Fe2+ concentration and mitochondrial ultrastructure. By performing interactive proteomics analyses in lung tumor cells, we identified the interaction between CTRP6 and suppressor of cytokine signaling 2 (SOCS2) leading to SOCS2 ubiquitination degradation, subsequently enhancing the downstream xCT/GPX4 signaling pathway. Moreover, significant correlations between CTRP6-mediated SOCS2 and ferroptosis were revealed in mouse models and clinical specimens of lung cancer. As inducing ferroptosis has been gradually regarded as an alternative strategy to treat tumors, targeting CTRP6-mediated ferroptosis could be a potential strategy for lung cancer therapy.

Correlation of serum subfatin, cthrc1, ctrp3, ctrp6 levels with disease indices in patients with axial spondyloarthritis.

BACKGROUND: The study aimed to investigate novel biomarkers from the C1q TNF superfamily and evaluate their role in autoimmune inflammatory rheumatic diseases with the goal of identifying an effective biomarker to measure clinical disease activity and assess treatment efficacy. METHODS: Sixty-one Axial spondyloarthritis (AxSpa) patients and 30 healthy controls were enrolled in the study. The serum biomarkers subfatin, CTHRC1, CTRP3, CTRP6, IL-6, IL-17, and TNF-α and the disease indices BASDAI, BASFI, MASES, and ASDAS-ESR/CRP were evaluated and compared. The patients were then classified, and their serum biomarkers were assessed according to their ASDAS scores and their treatment regimens. RESULTS: Among the studied biomarkers, none showed a significant difference between the patients and the healthy controls. Although the difference was not statistically significant, the median values of serum subfatin, CTHRC1, CTRP3, CTRP6, IL-6, IL-17, and TNF-α were all found to be lower in the AxSpa patients than in the healthy controls. Furthermore, once the patients were classified regarding their disease activity, no correlation between the study biomarkers and levels of clinical disease indices was observed. Finally, biological treatments were found to affect the serum concentration of these biomarkers regardless of the level of disease activity. CONCLUSION: Novel adipokines and known modulators of inflammation, circulating subfatin, CTHRC1, CTRP3, CTRP6, IL-6, IL-17, and TNF-α levels may play a role in assessing treatment efficacy, especially in those treated with TNF-inhibitors. However, we failed to demonstrate a correlation between clinical disease activity and serum biomarker levels.

CTRP6 regulates M1 macrophage polarization via the PPAR-γ/NF-κB pathway and reprogramming glycolysis in recurrent spontaneous abortion.

Aberrant polarization and functions of decidual macrophages are closely related to recurrent spontaneous abortion (RSA). C1q/tumor necrosis factor-related protein 6 (CTRP6) is a member of the adiponectin paralog family, and plays indispensable roles in inflammation, glucose uptake and tumor metastasis. However, the regulatory effect of CTRP6 on macrophage polarization and glycolysis in RSA and the underlying mechanisms have not been fully elucidated. In the present study, we first found that CTRP6 expression was positively correlated with the M1 macrophage marker (CD86) in decidual tissues by dual immunofluorescence analysis. In vitro experiments indicated that CTRP6 could facilitate M1 macrophage activation through the PPAR-γ/NF-κB pathway and manipulate the glycolysis of macrophages. Notably, in addition to silencing CTRP6, treatment with a PPAR-γ agonist (GW1929) inhibited M1 macrophage polarization and rescued embryo absorption in vivo. Taken together, these results identify previously unrevealed functions of CTRP6 in macrophage transformation during RSA.

C1q/TNF-Related Proteins 1, 6 and 8 Are Involved in Corneal Epithelial Wound Closure by Targeting Relaxin Receptor RXFP1 In Vitro.

Inadequate wound healing of ocular surface injuries can lead to permanent visual impairment. The relaxin ligand-receptor system has been demonstrated to promote corneal wound healing through increased cell migration and modulation of extracellular matrix formation. Recently, C1q/tumor necrosis factor-related protein (CTRP) 8 was identified as a novel interaction partner of relaxin receptor RXFP1. Additional data also suggest a role for CTRP1 and CTRP6 in RXFP1-mediated cAMP signaling. However, the role of CTRP1, CTRP6 and CTRP8 at the ocular surface remains unclear. In this study, we investigated the effects of CTRP1, CTRP6, and CTRP8 on epithelial ocular surface wound closure and their dependence on the RXFP1 receptor pathway. CTRP1, CTRP6, and CTRP8 expression was analyzed by RT-PCR and immunohistochemistry in human tissues and cell lines derived from the ocular surface and lacrimal apparatus. In vitro ocular surface wound modeling was performed using scratch assays. We analyzed the effects of recombinant CTRP1, CTRP6, and CTRP8 on cell proliferation and migration in human corneal and conjunctival epithelial cell lines. Dependence on RXFP1 signaling was established by inhibiting ligand binding to RXFP1 using a specific anti-RXFP1 antibody. We detected the expression of CTRP1, CTRP6, and CTRP8 in human tissue samples of the cornea, conjunctiva, meibomian gland, efferent tear ducts, and lacrimal gland, as well as in human corneal, conjunctival, and meibomian gland epithelial cell lines. Scratch assays revealed a dose-dependent increase in the closure rate of surface defects in human corneal epithelial cells after treatment with CTRP1, CTRP6, and CTRP8, but not in conjunctival epithelial cells. Inhibition of RXFP1 fully attenuated the effect of CTRP8 on the closure rate of surface defects in human corneal epithelial cells, whereas the CTRP1 and CTRP6 effects were not completely suppressed. Conclusions: Our findings demonstrate a novel role for CTRP1, CTRP6, and CTRP8 in corneal epithelial wound closure and suggest an involvement of the relaxin receptor RXFP1 signaling pathway. This could be a first step toward new approaches for pharmacological and therapeutic intervention.

C1q/tumor necrosis factor-related protein-6 exerts protective effects on myocardial ischemia-reperfusion injury through the modulation of the Akt-GSK-3ß-Nrf2 signaling cascade.

C1q/tumor necrosis factor-related protein-6 (CTRP6) is a multifunctional protein that plays a pivotal role in diverse physiological and pathological processes. To date, whether CTRP6 has a role in myocardial ischemia-reperfusion (I/R) injury remains unexplored. This work aimed to investigate the potential role and mechanism of CTRP6 in myocardial I/R injury through in vitro and in vivo experiments. CTRP6 expression was downregulated in hypoxia/reoxygenation (H/R)-treated cardiomyocytes. The apoptosis, oxidative stress, and inflammation in the H/R-treated cardiomyocytes were markedly alleviated by CTRP6 overexpression or exacerbated by CTRP6 silencing. Notably, the overexpression of CTRP6 remarkably ameliorated the myocardial injury, infarction area, cardiac apoptosis, oxidative stress, and inflammation in mice with myocardial I/R injury in vivo. Further investigation revealed that CTRP6 overexpression enhanced the activation of Nrf2 in the H/R-treated cardiomyocytes and the myocardium tissue of mice with myocardial I/R injury. CTRP6 overexpression increased the phosphorylated level of Akt and GSK-3ß, and the inhibition of Akt abolished CTRP6-overexpression-elicited Nrf2 activation in the H/R-treated cardiomyocytes. Additionally, the inhibition of Akt or Nrf2 abolished the protective effects of CTRP6 overexpression on the H/R-treated cardiomyocytes. Altogether, CTRP6 had protective effects on myocardial I/R injury via the effects on the Akt-GSK-3ß-Nrf2 signaling cascade. Our work recommends CTRP6 as a novel cardioprotective target for the treatment of myocardial I/R injury.

CTRP6 suppresses neutrophil extracellular traps formation to ameliorate sepsis-induced lung injury through inactivation of ERK pathway.

BACKGROUND: Septic lung injury is associated with excessive neutrophil activation, while neutrophil extracellular traps formation contributes to inflammatory lung injury in sepsis. C1q/tumor necrosis factor-related protein-6 (CTRP6) is a paralog of adiponectin and exerts anti- inflammatory and antioxidant properties. The role of CTRP6 in sepsis-associated inflammatory lung injury was investigated in this study. METHODS: Mice were injected with lipopolysaccharides (LPS) intraperitoneally to establish the mouse sepsis model. They were first tail-vein injected with adenovirus-mediated overexpression CTRP6 (Ad-CTRP6) and then subjected to the LPS injection. Pathological changes in lungs were detected by hematoxylin and eosin staining. Inflammation cytokine levels in bronchoalveolar lavage fluid were assessed by qRT-PCR and ELISA. Flow cytometry was used to detect the number of neutrophils in bronchoalveolar lavage fluid, and immunofluorescence was performed to assess neutrophil extracellular traps. RESULTS: Lipopolysaccharides induced pulmonary congestion, interstitial edema, and alveolar wall thickening in the lungs, as well as upregulated lung histology score and wet/dry weight ratio. CTRP6 was reduced in lung tissues of septic mice. Injection with Ad-CTRP6 ameliorated extensive histopathological changes in LPS-induced mice and decreased lung histology score and wet/dry weight ratio. Overexpression of CTRP6 reduced the levels of TNF-α, IL-6, and IL-1ß in septic mice. Injection with Ad-CTRP6 also decreased the number of neutrophils and downregulated Cit-H3 and myeloperoxidase polymers in septic mice. Protein expression of p-ERK in septic mice was reduced by overexpression of CTRP6. CONCLUSION: CTRP6 attenuated septic lung injury, exerted anti-inflammatory effect, and suppressed neutrophil extracellular traps formation against sepsis through inactivation of extracellular signal-regulated kinase signaling.

CTRP6 suppresses neutrophil extracellular traps formation to ameliorate sepsis-induced lung injury through inactivation of ERK pathway

extracellular traps formation contributes to inflammatory lung injury in sepsis. C1q/tumor necrosis factor–related protein-6 (CTRP6) is a paralog of adiponectin and exerts anti- inflammatory and antioxidant properties. The role of CTRP6 in sepsis-associated inflammatory lung injury was investigated in this study. Methods: Mice were injected with lipopolysaccharides (LPS) intraperitoneally to establish the mouse sepsis model. They were first tail-vein injected with adenovirus-mediated overexpression CTRP6 (Ad-CTRP6) and then subjected to the LPS injection. Pathological changes in lungs were detected by hematoxylin and eosin staining. Inflammation cytokine levels in bronchoalveolar lavage fluid were assessed by qRT-PCR and ELISA. Flow cytometry was used to detect the number of neutrophils in bronchoalveolar lavage fluid, and immunofluorescence was performed to assess neutrophil extracellular traps. Results: Lipopolysaccharides induced pulmonary congestion, interstitial edema, and alveolar wall thickening in the lungs, as well as upregulated lung histology score and wet/dry weight ratio. CTRP6 was reduced in lung tissues of septic mice. Injection with Ad-CTRP6 ameliorated extensive histopathological changes in LPS-induced mice and decreased lung histology score and wet/dry weight ratio. Overexpression of CTRP6 reduced the levels of TNF-α, IL-6, and IL-1β in septic mice. Injection with Ad-CTRP6 also decreased the number of neutrophils and downregulated Cit-H3 and myeloperoxidase polymers in septic mice. Protein expression of p-ERK in septic mice was reduced by overexpression of CTRP6. Conclusion: CTRP6 attenuated septic lung injury, exerted anti-inflammatory effect, and suppressed neutrophil extracellular traps formation against sepsis through inactivation of extracellular signal-regulated kinase signaling (AU)

Potential participation of CTRP6, a complement regulator, in the pathology of age related macular degeneration.

PURPOSE: To investigate the localized expression of C1q/tumor necrosis factor related protein (CTRP) 6 in human age-related macular degeneration (AMD) retinal tissues. EXPERIMENTAL STUDY DESIGN: 4 AMD and 3 non-AMD whole eyes of Caucasian donors were used. Eyecups were excised at Eye Bank CorneaGen, Inc. METHODS: To elucidate the effects of CTRP6, C3b was measured by an enzyme-linked immunosorbent-like assay. CFB versus CTRP6 competitive binding assay was applied to clarify the inhibition by CTRP6 of C3bBb complex formation. The cornea, iris, lens, and vitreous were removed and the eyes were cut into a posterior eye-cup including the retina, choroid, and sclera. Six-µm-thick serial sections of frozen samples underwent hematoxylin-eosin (HE) staining and indirect immunohistochemical staining using primary antibodies, anti-CTRP6, -CTRP5, -CTRP10, -Complement factor H (CFH) and -Clusterin (CLU). Results The two in vitro studies confirmed that CTRP6 has an inhibitory effect on alternative pathways of complement (APC) function and that the molecular target of CTRP6 is the inhibition of the formation of C3bBb. Localized expression for CTRP6 and CFH was found in the drusen of the AMD eyes, both associated with APC inhibition, CLU associated with membrane-attack complex (MAC) inhibition, and CTRP5 associated with retinal degeneration. CONCLUSION: The localized expression of CTRP6 in the drusen of AMD eyes may open a new insight into the possible involvement of APC regulatory factors in the pathogenesis of AMD, together with the known CFH so far analyzed solely as an APC inhibitor.

C1q/tumor necrosis factor related protein 6 (CTRP6) regulates the phenotypes of high glucose-induced gestational trophoblast cells via peroxisome proliferator-activated receptor gamma (PPARγ) signaling.

Multiple studies have confirmed that adipokines are compactly relevant to insulin resistance and participate in the pathogenesis of gestational diabetes mellitus (GDM). This paper aimed to study the effects of C1q/tumor necrosis factor related protein (CTRP)6 on the phenotypes of trophoblast cells, covering cell proliferation, invasion and migration, and initially explore the mechanism. High glucose was used to induce trophoblast cells to establish an in vitro model. The expression levels of CTRP6 were firstly determined, and then the effects of CTRP6 knockdown on cell viability, apoptosis, migration and invasion were assessed using CCK8, TUNEL, wound healing, Transwell assays. Moreover, the role of peroxisome proliferator-activated receptor gamma (PPARγ), probable target of CTRP6, was evaluated through co-transfection with PPARγ overexpression vector. The results of the present study revealed that CTRP6 and PPARγ were both upregulated in high glucose-induced cells. And CTRP6 knockdown could significantly elevate the abilities of cell viability, migration and invasion, and avoid cell apoptosis. In addition, PPARγ overexpression was found to restrain the protective effects of CTRP6 knockdown on the above aspects, indicating CTRP6 played a role in trophoblast cells via inhibiting PPARγ expression. In conclusion, CTRP6 regulated the viability, migration and invasion of high glucose-induced gestational trophoblast cells through PPARγ signaling.

Adipocyte factor CTRP6 inhibits homocysteine-induced proliferation, migration, and dedifferentiation of vascular smooth muscle cells through PPARγ/NLRP3.

NLRP3 and PPARγ play important roles in the development of atherosclerosis (AS). Studies have shown that PPARγ regulates the expression of NLRP3 in vascular diseases. In addition, the adipocyte factor CTRP6 can improve the activation of PPARγ in vascular diseases. However, the regulatory relationship between CTRP6, PPARγ, and NLRP3 in AS and its underlying mechanism have not been reported. Since proliferation, migration, and dedifferentiation of vascular smooth muscle cells (VSMCs) are key events in AS, in this study, we induced proliferation, migration, and dedifferentiation of VSCMs through homocysteine (HCY) to detect the specific effects of CTRP6, PPARγ, and NLRP3. Subsequently, CTRP6 was overexpressed and the PPARγ inhibitor GW9662 and agonist rosiglitazone were administered to HCY-induced VSCMs to investigate the mechanisms. The results show that the expression of CTRP6 decreased in HCY-induced VSMCs. In addition, CTRP6 overexpression inhibited the proliferation and migration of HCY-induced VSMCs, as well as cell cycle acceleration and dedifferentiation. Overexpression of CTRP6 increased HCY-induced PPARγ expression and inhibited NLRP3 expression. The addition of GW9662 and rosiglitazone further demonstrated that overexpression of CTRP6 inhibited HCY-induced VSMC proliferation, migration, and dedifferentiation through PPARγ/NLRP3 signaling. In conclusion, CTRP6 inhibited HCY-induced proliferation, migration, and dedifferentiation of VSMCs through PPARγ/NLRP3.

CTRP6(C1q/Tumor Necrosis Factor (TNF)-related protein-6) alleviated the sevoflurane induced injury of mice central nervous system by promoting the expression of p-Akt (phosphorylated Akt).

Postoperative cognitive impairment and nervous system damage caused by anesthetics seriously affect patient's postoperative recovery. Recent study has revealed that CTRP6 could alleviate apoptosis, inflammation and oxidative stress of nerve cells, thereby relieving nervous system damage induced by cerebral ischemia reperfusion. However, whether CTRP6 could relieve sevoflurane induced central nervous system injury is unclear. We stimulated C57BL/6 mice with sevoflurane and injected CTRP6 overexpression adenovirus vector. Next, H&E staining and TUNEL assays were performed to examine the effect of CTRP6 on sevoflurane induced injury of central nervous system. Finally, we isolated primary nerve cells of hippocampus. Flow cytometry and commercial kits were used for the detection of apoptosis and ROS levels of these cells. Western blotting was used for the detection of the expression level of p-Akt in central nervous tissues and primary cells. Results showed that sevoflurane induced injury and apoptosis of central nervous tissues. Overexpression of CTRP6 relieved apoptosis and injury of these tissues. CTRP6 inhibited the expression of cleaved caspase-3 and cleaved PARP in these tissues. Sevoflurane promoted apoptosis of primary cells and enhanced the expression of ROS and MDA in these cells. Overexpression of CTRP6 alleviated apoptosis and suppressed production of ROS and MDA in these cells. In addition, CTRP6 also enhanced the expression of p-Akt in primary cells. Taken together, our results suggested that CTRP6 relieved sevoflurane induced injury of central nervous tissues by promoting the expression of p-Akt. Therefore, the targeted drug of CTRP6 should be explored for the remission of these symptoms.

MicroRNA-29b/29c targeting CTRP6 influences porcine adipogenesis via the AKT/PKA/MAPK Signalling pathway.

Porcine fat deposition is an important economic trait of pig breeds, and understanding the gene regulatory network in adipocytes is essential for modern pig breeding. In a previous study, we demonstrated that miR-29a negatively regulates the differentiation of porcine adipocytes. In this study, we investigated the roles of miR-29b/c in porcine adipocytes and the underlying mechanisms. Using EdU staining and the CCK-8 assay, we observed that transfection with the miR-29b/c agomir promoted the proliferation of porcine intramuscular (IM) and subcutaneous (SC) adipocytes by altering the expression of cell-cycle-related genes. According to the results of oil red O staining and western blot analysis, transfection with the miR-29b/c agomir suppressed the differentiation of porcine SC and IM adipocytes via the AKT/PKA/MAPK signalling pathway. Furthermore, we proved that miR-29b/c regulates porcine adipocytes by directly targeting the 3'-untranslated region (3'UTR) of CTRP6 using a dual-luciferase reporter assay. Finally, co-transfection with miR-29b/c and CTRP6 partially restored the changes of phenotype and gene expression induced by miR-29b/c overexpression in 3T3-L1 adipocytes. Taken together, our data demonstrate that both miR-29b and miR-29 c negatively regulate porcine adipogenesis by targeting CTRP6, which furthers our understanding of the gene network that regulates fat deposition in pigs.

Anti-fibrotic properties of an adiponectin paralog protein, C1q/TNF-related protein 6 (CTRP6), in diffuse gastric adenocarcinoma.

Patients with advanced gastric cancer, especially diffuse-type gastric cancer, which is often accompanied by stromal fibrosis, commonly exhibit a poor prognosis. This study was designed to unravel the potential roles of C1q/TNF-related protein 6 (CTRP6) in the fibrotic cancer microenvironment of diffuse-type gastric adenocarcinoma. A total of 49 diffuse-type gastric cancer samples were evaluated in this study, and 23 of these samples exhibited focal CTRP6 immunoreactivity. CTRP6 immunoreactivity was found to be correlated with favorable survival outcomes, in terms of both overall and relapse-free survival rates, but this trend did not reach significance (P = 0.15). By contrast, CTRP6 immunoreactivity was significantly correlated with relapse-free survival rates in patients with diffuse-type gastric cancer at a distal site (P = 0.028). Notably, most gastric cancer cells at the cancer invasive front were CTRP6 negative, especially in areas of robust fibrosis. Double immunohistochemical staining demonstrated an inverse expression profile for CTRP6 and the activated fibroblast marker alpha smooth muscle actin (α-sma) in stromal and gastric cancer cells at the cancer invasion front. The addition of recombinant CTRP6 protein attenuated the TGF-ß-induced α-sma expression in cultured human fibroblasts but did not alter the proliferation rate or Matrigel-invasion activity of the cultured gastric cancer cells. In addition, CTRP6 did not affect the viability of normal human gastric epithelial cells. This study suggests that CTRP6 may have potential application in combating stromal fibrosis in diffuse-type gastric cancers.

Role of the CTRP6/AMPK pathway in kidney fibrosis through the promotion of fatty acid oxidation.

CTRP6, a newly identified adiponectin analogue, has been shown to be involved in inflammation, diabetes and cardiovascular diseases. Recently, increasing evidence has shown that CTRP6 plays a critical role in fibrotic diseases, such as myocardial fibrosis and skin fibrosis. FAO, an important energy source for kidney proximal tubular cells, also participates in the process of fibrosis. Therefore, our study aimed to investigate the effect of CTRP6 on mediating FAO in kidney fibrosis and the underlying associated mechanism. Firstly, the activity of CTRP6 and the key enzymes of FAO (CPT1A, ACOX1) were tested in vivo and vitro. Next, the regulatory effect of CTRP6/AMPK on FAO was accessed in animal models and in cell lines. Additionally, we explored the effect of exogenous recombinant CTRP6 on renal tubular epithelial cell differentiation. Decreased CTRP6 and p-AMPK were detected in UUO-induced kidney fibrosis and in TGF-ß1-treated HK-2 cells. We also observed that defective FAO occurred during kidney fibrosis. Moreover, the human CTRP6 peptide could inhibit the ECM deposition and promote the phosphorylation of AMPK by promoting FAO. However, the inhibitory effects of CTRP6 on TGF-ß1-induced ECM deposition and the protective effects of CTRP6 on FAO could be abolished by compound C, a selective inhibitor of AMPK. Compound C also reversed the CTRP6-mediated upregulation of p-AMPK. The mediation of FAO by CTRP6 plays a key role in kidney fibrosis by regulating TGF-ß1-induced renal tubular epithelial cell differentiation by promoting FAO, which is mediated via AMPK activation.

[Effect of high-fat diet and exercise on asprosin and CTRP6 expression in subcutaneous and retroperitoneal adipose tissues in rats during mid-gestation].

OBJECTIVE: To study the effects of high-fat (HF) diet and exercise on the expressions of asprosin and CTRP6 in adipose tissues in different regions of rats during mid-gestation. METHODS: Pregnant SD rats were fed on a standard chow diet or a high-fat (60% fat content) diet for 14 days starting on gestation day (GD) 1. Starting from GD3, the rats fed either on normal or high-fat diet in the exercise groups (CH-RW and HF-RW groups) were allowed access to the running wheels for voluntary running, and those in sedentary groups (CH-SD and HF-SD groups) remained sedentary. At the end of the 14 days, adipose tissues were sampled from different regions of the rats for detecting the mRNA and protein expressions of asprosin and CTRP6 using RT-qPCR and Western blotting. RESULTS: The mRNA expression of asprosin in retroperitoneal adipose tissues was significantly higher in HF-RW group than in the other 3 groups (P < 0.0001). Asprosin mRNA expression in subcutaneous adipose tissues was significantly higher in HF-SD group than in CH-SD group (P=0.0234) and comparable between HF-RW and CH-SD groups (P=0.0494). CTRP6 mRNA expression in retroperitoneal adipose tissues was also significantly higher in HF-RW group than in the other groups (P < 0.0001), and CTRP6 protein expression was signficiantly higher in HF-RW group than in CH-RW and HF-SD groups (P < 0.05). In subcutaneous adipose tissues, CTRP6 mRNA expression was significantly higher in CH-RW group than in HF-SD and HF-RW groups (P < 0.05). The protein expression level of CTRP6 in subcutaneous adipose tissues showed a significant negative correlation with blood glucose (r=-0.6038, P=0.0172), while its expression in retroperitoneal adipose tissues was positively correlated with blood glucose (r=0.5305, P= 0.0285); the mRNA expression levels of asprosin and CTRP6 were significantly lower in subcutaneous than in retroperitoneal adipose tissues (P < 0.0001). CONCLUSIONS: High-fat diet and exercise during mid-gedtation can affect the expression levels of asprosin and CTRP6 in adipose tissues of rats in a site-specific manner.