αMSH promotes preadipocyte proliferation by alleviating ER stress-induced leptin resistance and by activating Notch1 signal in mice

LncRNA ENSGALG00000021686 regulates fat metabolism in chicken hepatocytes via miR-146b/AGPAT2 pathway

The liver contributes to lipid metabolism as the hub of fat synthesis. Long non-coding RNAs (lncRNAs) are considered the regulators of cellular processes. Since LncRNA ENSGALG00000021686 (lncRNA 21 686) has been described as a regulator of lipid metabolism, the present study aimed to clarify the role of lncRNA 21 686 in chicken hepatocytes' lipid metabolism. Thirty-two chickens were divided into four groups and were treated with diets containing different amounts of fat, and the hepatic expression of lncRNA 21 686 and miR-146b along with the levels of proteins involved in the regulation of fat metabolism, lipid indices and oxidative stress were measured. Moreover, primary chicken hepatocytes were transfected with lncRNA 21 686 small interfering RNA or microRNA (miRNA, miR)-146b mimics to measure the consequences of suppressing lncRNA or inducing miRNA expression on the levels of proteins involved in fat metabolism and stress markers. The results showed that the high-fat diet modulated the expression of lncRNA 21 686 and miR-146b (p-value < 0.001). Moreover, there was a significant increase in 1-acyl-sn-glycerol-3-phosphate acyltransferase 2 (AGPAT2) gene expression and protein levels and modulated fat-related markers. Furthermore, the results showed that lncRNA 21 686 suppression reduced the expression of AGPAT2 and its downstream proteins (p-value < 0.05). Overexpression of miR-146b regulated fat metabolism indicator expression. Transfection experiments revealed that lncRNA 21 686 suppression increased miR-146b expression. The findings suggested a novel mechanism containing lncRNA 21 686/miR-146b/AGPAT2 in the regulation of fat metabolism in chicken hepatocytes.

EGCG Suppresses Adipogenesis and Promotes Browning of 3T3-L1 Cells by Inhibiting Notch1 Expression

BACKGROUND

With the changes in lifestyle and diet structure, the incidence of obesity has increased year by year, and obesity is one of the inducements of many chronic metabolic diseases. Epigallocatechin gallate (EGCG), which is the most abundant component of tea polyphenols, has been used for many years to improve obesity and its complications. Though it has been reported that EGCG can improve obesity through many molecular mechanisms, EGCG may have many mechanisms yet to be explored. In this study, we explored other possible mechanisms through molecular docking and in vitro experiments.

METHODS

AutoDock Vina was selected for conducting the molecular docking analysis to elucidate the interaction between EGCG and Notch1, while molecular dynamics simulations were employed to validate this interaction. Then, the new regulation mechanism of EGCG on obesity was verified with in vitro experiments, including a Western blot experiment, immunofluorescence experiment, oil red O staining, and other experiments in 3T3-L1 adipocytes.

RESULTS

The molecular docking results showed that EGCG could bind to Notch1 protein through hydrogen bonding. In vitro cell experiments demonstrated that EGCG can significantly reduce the sizes of lipid droplets of 3T3-L1 adipocytes and promote UCP-1 expression by inhibiting the expression of Notch1 in 3T3-L1 adipocytes, thus promoting mitochondrial biogenesis.

CONCLUSIONS

In this study, molecular docking and in vitro cell experiments were used to explore the possible mechanism of EGCG to improve obesity by inhibiting Notch1.

Screening and functional validation of lipid metabolism-related lncRNA-46546 based on the transcriptome analysis of early embryonic muscle tissue in chicken

OBJECTIVE

The study was conducted to screen differentially expressed long noncoding RNA (lncRNA) in chickens by high-throughput sequencing and explore its mechanism of action on intramuscular fat deposition.

METHODS

Herein, Rose crown and Cbb broiler chicken embryo breast and leg muscle lncRNA and mRNA expression profiles were constructed by RNA sequencing. A total of 96 and 42 differentially expressed lncRNAs were obtained in Rose crown vs Cobb broiler chicken breast and leg muscle, respectively. lncRNA-ENSGALT00000046546, with high interspecific variability and a potential regulatory role in lipid metabolism, and its predicted downstream target gene 1-acylglycerol-3-phosphate-O-acyltransferase 2 (AGPAT2), were selected for further study on the preadipocytes.

RESULTS

lncRNA-46546 overexpression in chicken preadipocyte 2 cells significantly increased (p<0.01) the expression levels of AGPAT2 and its downstream genes diacylglycerol acyltransferase 1 and diacylglycerol acyltransferase 2 and those of the fat metabolism-related genes peroxisome proliferator-activated receptor γ, CCAAT/enhancer binding protein α, fatty acid synthase, sterol regulatory element-binding transcription factor 1, and fatty acid binding protein 4. The lipid droplet concentration was higher in the overexpression group than in the control cells, and the triglyceride content in cells and medium was also significantly increased (p<0.01).

CONCLUSION

This study preliminarily concludes that lncRNA-46546 may promote intramuscular fat deposition in chickens, laying a foundation for the study of lncRNAs in chicken early embryonic development and fat deposition.

Homocysteine causes neuronal leptin resistance and endoplasmic reticulum stress

Abnormally high serum homocysteine levels have been associated with several disorders, including obesity, cardiovascular diseases or neurological diseases. Leptin is an anti-obesity protein and its action is mainly mediated by the activation of its Ob-R receptor in neuronal cells. The inability of leptin to induce activation of its specific signaling pathways, especially under endoplasmic reticulum stress, leads to the leptin resistance observed in obesity. The present study examined the effect of homocysteine on leptin signaling in SH-SY5Y neuroblastoma cells expressing the leptin receptor Ob-Rb. Phosphorylation of the signal transducer and activator of transcription (STAT3) and leptin-induced STAT3 transcriptional activity were significantly inhibited by homocysteine treatment. These effects may be specific to homocysteine and to the leptin pathway, as other homocysteine-related compounds, namely methionine and cysteine, have weak effect on leptin-induced inhibition of STAT3 phosphorylation, and homocysteine has no impact on IL-6-induced activation of STAT3. The direct effect of homocysteine on leptin-induced Ob-R activation, analyzed by Ob-R BRET biosensor to monitor Ob-R oligomerization and conformational change, suggested that homocysteine treatment does not affect early events of leptin-induced Ob-R activation. Instead, we found that, unlike methionine or cysteine, homocysteine increases the expression of the endoplasmic reticulum (ER) stress response gene, a homocysteine-sensitive ER resident protein. These results suggest that homocysteine may induce neuronal resistance to leptin by suppressing STAT3 phosphorylation downstream of the leptin receptor via ER stress.

α-MSH is partially involved in the immunomodulation of Nile tilapia (Oreochromis niloticus) antibacterial immunity

α-Melanocyte-stimulating hormone (α-MSH) is a well-studied neuropeptide controlling skin and hair color. Besides, numerous immunomodulation roles of α-MSH were recorded in humans and mice. However, the regulatory effects of α-MSH in teleost immunity haven't been well elucidated. In this study, several precursor molecules of α-MSH (POMCs) and its receptors (MCRs) in Nile tilapia (Oreochromis niloticus) were characterized, and their expression characteristics and specific functions on antibacterial immunity were determined. Overall, POMCs and MCRs were principally detected in the brain, skin, and liver, and were remarkably promoted post Streptococcus agalactiae infection. However, tiny POMCs and MCRs were observed in tilapia immune organs (head kidney and spleen) or lymphocytes, and no evident immunomodulation effect was detected in vitro. Moreover, the in vivo challenge experiments revealed that α-MSH protects tilapia from bacterial infection by regulating responses in the brain and intestine. This study lays theoretical data for a deeper comprehension of the immunomodulation mechanisms of teleost α-MSH and the evolutional process of the vertebrate melanocortin system.

HOXA5 inhibits adipocytes proliferation through transcriptional regulation of Ccne1 and blocking JAK2/STAT3 signaling pathway in mice

The highly regulated proliferation of adipocytes plays a momentous role in fat development and obesity. Hoxa5 is an important member of Hox family, its encoded protein is an important transcription factor related to development. And its differential expression in different adipose tissues seems to indicate that Hoxa5 may be involved in the regulation of adipocyte proliferation. In order to evaluate the regulation mechanism of Hoxa5 on adipocyte proliferation, we constructed a variety of Hoxa5 expression vectors in vivo and in vitro to explore its mechanism on adipocyte proliferation and its potential impact on obesity. We have observed that the overexpression of Hoxa5 strongly reduces cell counts, and Hoxa5 can inhibit cell proliferation and block cell cycle progression by regulating the expression of genes such as Cyclin E, Cycling D1 and p53. Most importantly, we demonstrated that Hoxa5 exerts its effect by regulating the signaling pathway of Janus kinase 2 (JAK2) signal transduction and transcription 3 (STAT3) activator, as well as binding to the promoter region of Ccne1 and inhibiting the transcription of Ccne1.This study provides an in-depth understanding of the potential molecular mechanism of Hoxa5 inhibiting adipocyte proliferation. Our results suggest the importance of Hoxa5 in the treatment of obesity.

Lnc-hipk1 inhibits mouse adipocyte apoptosis as a sponge of miR-497

Noncoding RNAs (ncRNAs) such as microRNAs (miRNAs), long noncoding RNAs (lncRNA), and circular RNAs are closely related to the biological processes related to obesity. As a miRNA that widely present in different cell types, miR497 is proved to be involved in cell development. However, research on the role of miR-497 as a key factor in regulating the development of adipocytes is still in gap. The role of miR-497 in the apoptosis and proliferation of mouse-derived adipocytes was detected by RNA-seq analysis, RT-qPCR, Western blot, immunofluorescence, and dual-luciferase reporter assay. Using miR-497 mimics to treat 3T3-L1 cells, we found that miR-497 targeted Bcl-2 to promote adipocyte apoptosis through the mitochondrial pathway, and this effect was consistent in the apoptosis model composed of palmitic acid (PA) and hydrogen peroxide (H₂ O₂ ). LncRNA homeodomain-interacting protein kinase 1 (lnc-hipk1) sponged miR-148b to weaken its silencing of Bcl-2, forming the competitive endogenous RNAs (CeRNAs) regulatory network. Furthermore, overexpression of lnc-hipk1 inhibited the apoptosis of adipocytes by targeting miR-497/Bcl-2. Co-treatment of miR-497 and lnc-hipk1 showed that lnc-hipk1 reversed the apoptosis of adipocytes caused by miR-497 overexpression. And in vivo experiments further confirmed that this effect was also achieved by the CeRNA system of lnc-hipk1/miR-497/Bcl-2. In summary, lnc-hipk1 targets miR-497/Bcl-2 to regulate adipocyte apoptosis through the mitochondrial pathway. This research enriches the research content of ncRNAs and CeRNA in adipocyte development, and provides new targets for the treatment of obesity and other metabolic syndromes.

Hoxa5 alleviates obesity-induced chronic inflammation by reducing ER stress and promoting M2 macrophage polarization in mouse adipose tissue

Obesity‐induced chronic inflammation is associated with endoplasmic reticulum stress (ERS) in adipocytes and changes in both the number and phenotype of adipose tissue macrophages (ATMs). In addition, ERS enhances macrophage activation. So far, the function of Hoxa5 in obesity‐induced chronic inflammation has been poorly understood. Herein, we demonstrate the importance of the transcription factor, Hoxa5, in determining adipose tissue macrophage (ATM) polarity and ERS. Hoxa5 decreased bodyweight, reduced inflammatory cytokine secretion and corresponded with an increased number of M2 macrophages in the adipose tissue of high‐fat diet (HFD) mice. Transcriptome sequencing data showed that overexpression of Hoxa5 in adipocytes changed expression of endoplasmic reticulum (ER) protein processing‐related genes. Based on transcriptome sequencing data and bioinformatics prediction, we have been suggested that Hoxa5 alleviated inflammatory responses by inhibiting ERS and by activating PPARγ pathway in mouse adipose tissue. Hoxa5 alleviated ERS and inflammatory responses by inhibiting the eIF2α/PERK signalling pathway in adipocytes. Hoxa5 also inhibited chronic inflammation of adipocytes by promoting M2 macrophage polarization. In addition, Hoxa5 transcriptionally activated the PPARγ pathway to promote polarization of M2 macrophages, which in turn alleviated chronic inflammation of adipocytes. Taken together, these results shed light on the mechanisms underlying Hoxa5‐dependent inhibition of obesity‐induced chronic inflammation by reducing ERS and promoting polarization of M2 macrophages. These results suggest that Hoxa5 may be a potential therapeutic target for obesity and other metabolic syndromes.

circARF3 Alleviates Mitophagy-Mediated Inflammation by Targeting miR-103/TRAF3 in Mouse Adipose Tissue

Adipose inflammation is an important cause for obesity-associated metabolic disorders, including insulin resistance and hypertension. Here we investigated that a circular RNA (circRNA), which we termed circARF3 (ADP-ribosylation factor 3), acts as an endogenous miR-103 sponge to alleviate adipose inflammation by promoting mitophagy. On the other hand, miR-103 aggravated inflammation by inhibiting mitophagy, revealing that miR-103 acts as a positive regulator of adipose inflammation. Furthermore, we found that tumor necrosis factor receptor-associated factor 3 (TRAF3), as a miR-103 downstream target, mediates the functions of miR-103 in adipose inflammation. Overexpressing TRAF3 attenuated miR-103-induced inflammation by accelerating mitophagy. Moreover, we identified that circARF3 blocked miR-103 effects, which resulted in an increase in TRAF3 expression. TRAF3 restrained the nuclear factor κB (NF-κB)-signaling pathway, heightened mitophagy, and suppressed NLRP3 inflammasome activation ultimately. Our data showed that circARF3 acts as an endogenous miR-103 sponge to inhibit mitophagy-mediated adipose inflammation both in vitro and in vivo. These findings disclose a new regulatory pathway for adipose inflammation, which consists of circARF3, miR-103, and TRAF3. This study can be a useful addition to our knowledge, as it provides a new strategy for the prevention of adipose inflammation in obesity disorder.

αMSH prevents ROS-induced apoptosis by inhibiting Foxo1/mTORC2 in mice adipose tissue

Alpha-melanocyte stimulating hormone (αMSH) is an important adenohypophysis polypeptide hormone that regulates body metabolic status. To date, it is well known that the disorder of hypothalamic αMSH secretion is related to many metabolic diseases, such as obesity and type II diabetes. However, the underlying mechanisms are poorly understood. In our study, we focused on the reactive oxygen species (ROS)-induced adipocyte apoptosis and tried to unveil the role of αMSH in this process and the signal pathway which αMSH acts through. Kunming white mice were used and induced to oxidative stress status by hydrogen peroxide (H2O2) injection and a significant reduction of αMSH were found in mice serum, while elevated ROS level and mRNA level of pro-apoptotic genes were observed in mice adipose tissue. What is more, when detect the function of αMSH in ROS-induced apoptosis, similar inhibitory trend was found with the oxidative stress inhibitor N-acetyl-L-cysteine (NAC) in ROS-induced adipocyte apoptosis and this trend is αMSH receptor melanocortin 5 receptor (MC5R) depended, while an opposite trend was found between αMSH and Foxo1, which is a known positive regulator of adipocyte apoptosis. Further, we found that the repress effect of αMSH in adipocytes apoptosis is acting through Foxo1/mTORC2 pathway. These findings indicate that, αMSH has a strong inhibitory effect on ROS-induced adipocyte apoptosis and underlying mechanism is interacting with key factors in mTOR signal pathway. Our study demonstrated a great role of αMSH in adipocyte apoptosis and brings a new therapeutic mean to the treatment of obesity and diabetes.

αMSH inhibits adipose inflammation via reducing FoxOs transcription and blocking Akt/JNK pathway in mice

Alpha melanocyte stimulating hormone (αMSH) abates inflammation in multiple tissues, while Forkhead box proteins O (FoxOs) stimulate inflammatory cascade. However, the relationship between αMSH and FoxOs in adipose inflammation remains unclear. In this study, we used LPS-induced inflammation model, attempted to interpret the function of αMSH in inflammation and the interactions with FoxOs. Results indicated that upon inflammatory situation, the secretion of αMSH and the expression of its receptor MC5R were greatly decreased, but FoxOs expressions were elevated. After the treatment with αMSH, LPS-induced adipose inflammation together with FoxOs expressions was significantly reduced. Conversely, when Foxo1, Foxo3a or Foxo4 overexpressed in αMSH treated inflammatory mouse model, all the anti-inflammatory impacts of αMSH were found disappeared. We further studied the mechanisms by which αMSH exerts its anti-inflammatory impacts and how FoxOs reverse αMSH's function. Foxo4 was found as a negative regulator for MC5R transcription in αMSH inhibited inflammation. Moreover, a negative role was found of αMSH in regulating both Akt and JNK signal pathways by observing the enhanced the anti-inflammatory impacts of pathway-specific inhibitors with αMSH treatment. Our findings demonstrate αMSH plays a key role in the prevention of adipose inflammation and inflammatory diseases by down-regulating Akt/JNK signal pathway and negatively interacting with FoxOs, which brings up αMSH as a novel candidate factor in the adipose anti-inflammation process in obesity.

Homeobox a5 Promotes White Adipose Tissue Browning Through Inhibition of the Tenascin C/Toll-Like Receptor 4/Nuclear Factor Kappa B Inflammatory Signaling in Mice

Lipopolysaccharide (LPS) induces rapid increase in systemic inflammatory factors. As adipose tissue is a key contributor to the inflammatory response to numerous metabolic stimuli, it is important to understand the mechanism behind the LPS-induced inflammation in white adipose tissue (WAT). Homeobox a5 (Hoxa5) is an important transcription factor, which is highly expressed in adipose tissue, and its mRNA expression is increased at cold exposure in mice. So far, the function of Hoxa5 in adipose tissue browning has been poorly understood. So, the objective of this study was conducted to determine the role of Hoxa5 in adipose inflammatory response and white adipose browning in mice. LPS-induced inflammatory and cold-induced browning model were conducted. We compared the coordinated role of Hoxa5 in inflammation and thermogenesis of mice adipose. Transcriptional and methylation regulation was determined by luciferase assay, electrophoretic mobility shift assay, and bisulfite conversion experiment. Hoxa5 and tenascin C (TNC) were involved in WAT inflammation and browning in mice with LPS injection. Furthermore, Hoxa5 inhibited the TNC-involved activation of Toll-like receptor (TLR) 4/nuclear factor kappa B (NF-κB) signal pathway and promoted WAT browning. Moreover, we found that a BMP4/Smad1 signal, closely related to browning, was activated by Hoxa5. Hoxa5 relieved adipocyte inflammation by decreasing TNC-mediated TLR4 transducer and activator of the NF-κB pathway. Interestingly, descended methylation level increased Hoxa5 expression in cold exposure. Our findings demonstrated that Hoxa5 alleviated inflammation and enhanced browning of adipose tissue via negative control of TNC/TLR4/NF-κB inflammatory signaling and activating BMP4/Smad1 pathway. These findings indicated a novel potential means for the regulation of inflammation in adipocytes to prevent obesity and other inflammatory diseases.

Isolation, culture, characterization, and osteogenic differentiation of canine endometrial mesenchymal stem cell

Aim

In this study, the canine endometrium tissue is characterized for its stem cell properties such as adherence to tissue culture plate (plasticity), short population doubling time, serial clonal passaging, long-term culturing properties, stem cell marker expression, and multilineage differentiation potential.

Materials and Methods

The present work describes a novel isolation protocol for obtaining mesenchymal stem cells from the uterine endometrium and is compared with cells derived from umbilical cord matrix as a positive control. These cells are clonogenic, can undergo several population doublings in vitro, and can be differentiated to the osteocytes in mature mesenchymal tissues when grown in osteogenic differentiation media as detected by Alizarin Red-S staining.

Results

It is reported for the first time that the cells derived from the canine endometrium (e-multipotent stem cells [MSCs]) were able to differentiate into a heterologous cell type: Osteocytes, thus demonstrating the presence of MSCs. Thus, the endometrium may be told as a potential source of MSCs which can be used for various therapeutic purposes.

Conclusion

The endometrium can be used as a potential source of MSCs, which can be used for various therapeutic purposes.

Hoxa5 increases mitochondrial apoptosis by inhibiting Akt/mTORC1/S6K1 pathway in mice white adipocytes

Homeobox A5(Hoxa5), a member of the Hox family, plays a important role in the regulation of proliferation and apoptosis in cancer cells. The dysregulation of the adipocyte apoptosis in vivo leads to obesity and metabolic disorders. However, the effects of Hoxa5 on adipocyte apoptosis are still unknown. In this study, palmitic acid (PA) significantly increased the mRNA level of Hoxa5 and triggered white adipocyte apoptosis in vivo and in vitro. Further analysis revealed that Hoxa5 enhanced the early and late apoptotic cells and fragmentation of genomic DNA in adipocytes from inguinal white adipose tissue (iWAT) of mice. Moreover, Hoxa5 aggravated white adipocyte apoptosis through mitochondrial pathway rather than endoplasmic reticulum stress (ERS)-induced or death receptor (DR)-mediated pathway. Our data also confirmed that Hoxa5 promoted mitochondrial apoptosis pathway by elevating the transcription activity of Bax and inhibiting the protein kinase B (Akt)/mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. In summary, these findings revealed a novel mechanism that linked Hoxa5 to white adipocyte apoptosis, which provided some potential possibilities to prevent and treat obesity and some metabolic diseases.

Melatonin alleviates inflammasome-induced pyroptosis through inhibiting NF-κB/GSDMD signal in mice adipose tissue

Pyroptosis is a proinflammatory form of cell death that is associated with pathogenesis of many chronic inflammatory diseases. Melatonin is substantially reported to possess anti-inflammatory properties by inhibiting inflammasome activation. However, the effects of melatonin on inflammasome-induced pyroptosis in adipocytes remain elusive. Here, we demonstrated that melatonin alleviated lipopolysaccharides (LPS)-induced inflammation and NLRP3 inflammasome formation in mice adipose tissue. The NLRP3 inflammasome-mediated pyroptosis was also inhibited by melatonin in adipocytes. Further analysis revealed that gasdermin D (GSDMD), the key executioner of pyroptosis, was the target for melatonin inhibition of adipocyte pyroptosis. Importantly, we determined that nuclear factor κB (NF-κB) signal was required for the GSDMD-mediated pyroptosis in adipocytes. We also confirmed that melatonin alleviated adipocyte pyroptosis by transcriptional suppression of GSDMD. Moreover, GSDMD physically interacted with interferon regulatory factor 7 (IRF7) and subsequently formed a complex to promote adipocyte pyroptosis. Melatonin also attenuated NLRP3 inflammasome activation and pyroptosis, which was induced by LPS or obesity. In summary, our results demonstrate that melatonin alleviates inflammasome-induced pyroptosis by blocking NF-κB/GSDMD signal in mice adipose tissue. Our data reveal a novel function of melatonin on adipocyte pyroptosis, suggesting a new potential therapy for melatonin to prevent and treat obesity caused systemic inflammatory response.