The forkhead transcription factor FOXO1 stimulates the expression of the adipocyte resistin gene

Resistin stimulates PC-3 prostate cancer cell growth through stimulation of SOCS3 and SOCS5 genes

Resistin and suppressors of cytokine signaling (SOCSs) have been reported to regulate prostate cancer (PCa) cell proliferation and survival, respectively. Whether any of the SOCS molecules mediate the mitogenic effect of resistin on PCa cells is unknown. Using PC-3 human PCa cells, we found that resistin upregulates the expression of SOCS3 and SOCS5 mRNA, but not SOCS7 mRNA, in a dose- and time-dependent manner. The resistin-induced increases in SOCS3 and SOCS5 expression and cell proliferation were prevented by pretreatment with specific inhibitors of the TLR4, ERK, p38 MAPK, JNK, PI3K, and JAK2 proteins. However, pretreatment with a TLR2 inhibitor had no effect on resistin-mediated SOCS3 and SOCS5 expression. In addition, the effects of resistin on SOCS3, SOCS5, and SOCS7 mRNA levels were cell type-specific. Overexpression of either SOCS3 or SOCS5 enhanced further resistin-stimulated growth of PC-3 cells, whereas silencing SOCS3 or SOCS5 antagonized resistin-increased cell growth. Further PCa tissue analysis demonstrated higher levels of RETN, TLR4, SOCS3, and SOCS5 mRNAs in cancer tissues than benign prostate hyperplasia and indicated positive correlations among RETN, TLR4, and SOCS5. These data suggest that SOCS5, TLR4, and, to a lesser extent, SOCS3 can mediate the mitogenic effect of resistin on PC-3 PCa cells.

Identification and verification of feature biomarkers associated with immune cells in neonatal sepsis

BACKGROUND

Neonatal sepsis (NS), a life-threatening condition, is characterized by organ dysfunction and is the most common cause of neonatal death. However, the pathogenesis of NS is unclear and the clinical inflammatory markers currently used are not ideal for diagnosis of NS. Thus, exploring the link between immune responses in NS pathogenesis, elucidating the molecular mechanisms involved, and identifying potential therapeutic targets is of great significance in clinical practice. Herein, our study aimed to explore immune-related genes in NS and identify potential diagnostic biomarkers. Datasets for patients with NS and healthy controls were downloaded from the GEO database; GSE69686 and GSE25504 were used as the analysis and validation datasets, respectively. Differentially expressed genes (DEGs) were identified and Gene Set Enrichment Analysis (GSEA) was performed to determine their biological functions. Composition of immune cells was determined and immune-related genes (IRGs) between the two clusters were identified and their metabolic pathways were determined. Key genes with correlation coefficient > 0.5 and p < 0.05 were selected as screening biomarkers. Logistic regression models were constructed based on the selected biomarkers, and the diagnostic models were validated.

RESULTS

Fifty-two DEGs were identified, and GSEA indicated involvement in acute inflammatory response, bacterial detection, and regulation of macrophage activation. Most infiltrating immune cells, including activated CD8 + T cells, were significantly different in patients with NS compared to the healthy controls. Fifty-four IRGs were identified, and GSEA indicated involvement in immune response and macrophage activation and regulation of T cell activation. Diagnostic models of DEGs containing five genes (PROS1, TDRD9, RETN, LOC728401, and METTL7B) and IRG with one gene (NSUN7) constructed using LASSO algorithm were validated using the GPL6947 and GPL13667 subset datasets, respectively. The IRG model outperformed the DEG model. Additionally, statistical analysis suggested that risk scores may be related to gestational age and birth weight, regardless of sex.

CONCLUSIONS

We identified six IRGs as potential diagnostic biomarkers for NS and developed diagnostic models for NS. Our findings provide a new perspective for future research on NS pathogenesis.

P38 MAPK pathway regulates the expression of resistin in porcine alveolar macrophages via Ets2 during Haemophilus parasuis stimulation

Haemophilus parasuis is a widespread bacterial pathogen causing acute systemic inflammation and leading to the sudden death of piglets. Resistin, a multifunctional peptide hormone previously demonstrated to influence the inflammation in porcine, was extremely increased in H. parasuis-infected tissues. However, the mechanism of resistin expression regulation in porcine, especially during pathogen infection, remains unclear. In the present study, we explored for the first time the transcription factor and signaling pathway mediating the expression of pig resistin during H. parasuis stimulation. We found that H. parasuis induced the expression of pig resistin in a time- and dose-dependent manner via the transcription factor Ets2 in porcine alveolar macrophages during H. parasuis stimulation. Moreover, the expression of Ets2 was mediated by the activation of the p38 MAPK pathway induced by H. parasuis, thus promoting resistin production. These results revealed a novel view of the molecular mechanism of pig resistin production during acute inflammation induced by pathogenic bacteria.

Bioinformatics Analysis for Identifying Pertinent Pathways and Genes in Sepsis

Purpose

Sepsis becomes the main death reason in hospitals with rising incidence, causing a growing economic and medical burden. However, the genes related to the pathogenesis and prognosis of sepsis are still unclear, which is a problem that needs to be solved urgently.

Materials and Methods

Gene expression profiles of GSE69528 were obtained from the National Center for Biotechnology Information. Limma software package got employed to search for differentially expressed genes (DEGs). Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) were used for enrichment analysis. Protein-protein interaction (PPI) network was built by the Search Tool for the Retrieval of Interacting Genes (STRING) database.

Results

We screened 101 DEGs, containing 81 upregulated DEGs and 20 downregulated DEGs. GO analysis demonstrated that the upregulated DEGs were chiefly concentrated in negative regulation of response to interferon-gamma and regulation of granulocyte differentiation. KEGG analysis revealed that the pathways of upregulated DEGs were concentrated in prion diseases, complement and coagulation cascades, and Staphylococcus aureus infection. The PPI network constructed by upregulated DEGs contained 67 nodes (proteins) and 110 edges (interactions). Analysis of bioinformatics results showed that CEACAM8, MPO, and RETN were hub genes of sepsis.

Conclusion

Our analysis reveals a series of signal pathways and key genes related to the mechanism of sepsis, which are promising biotargets and biomarkers of sepsis.

Endothelin-1 stimulates preadipocyte growth via the PKC, STAT3, AMPK, c-JUN, ERK, sphingosine kinase, and sphingomyelinase pathways

Endothelin (ET)-1 regulates adipogenesis and the endocrine activity of fat cells. However, relatively little is known about the ET-1 signaling pathway in preadipocyte growth. We used 3T3-L1 preadipocytes to investigate the signaling pathways involved in ET-1 modulation of preadipocyte proliferation. As indicated by an increased number of cells and greater incorporation of bromodeoxyuridine (BrdU), the stimulation of preadipocyte growth by ET-1 depends on concentration and timing. The concentration of ET-1 that increased preadipocyte number by 51-67% was ~100 nM for ~24-48 h of treatment. ET-1 signaling time dependently stimulated phosphorylation of ERK, c-JUN, STAT3, AMPK, and PKCα/βII proteins but not AKT, JNK, or p38 MAPK. Treatment with an ET_AR antagonist, such as BQ610, but not ET_BR antagonist BQ788, blocked the ET-1-induced increase in cell proliferation and phosphorylated levels of ERK, c-JUN, STAT3, AMPK, and PKCα/βII proteins. In addition, pretreatment with specific inhibitors of ERK1/2 (U0126), JNK (SP600125), JAK2/STAT3 (AG490), AMPK (compound C), or PKC (Ro318220) prevented the ET-1-induced increase in cell proliferation and reduced the ET-1-stimulated phosphorylation of ERK1/2, c-JUN, STAT3, AMPK, and PKCα/β. Moreover, the SphK antagonist suppressed ET-1-induced cell proliferation and ERK, c-JUN, STAT3, AMPK, and PKC phosphorylation, and the SMase2 antagonist suppressed ET-1-induced cell proliferation. However, neither the p38 MAPK antagonist nor the CerS inhibitor altered the effect of ET-1. The results indicate that ET_AR, JAK2/STAT3, ERK1/2, JNK/c-JUN, AMPK, PKC, SphK, and SMase2, but not ET_BR, p38 MAPK, or CerS, are necessary for the ET-1 stimulation of preadipocyte proliferation.

Ambient fine particulate matter exposure perturbed circadian rhythm and oscillations of lipid metabolism in adipose tissues

Emerging evidence indicated that disruption of circadian rhythm (CR) induced metabolic disorders, including dysregulation of energy homeostasis and lipid dysfunction, which was associated with ambient fine particulate matter (PM_2.5) as well. However, the role and mechanism of CR in PM_2.5-mediated metabolic disorder remain unknown. In the present study, we investigated circadian rhythmic characteristics and explored the effect of PM_2.5 on oscillating clock of lipid function and metabolism in white adipose tissue (WAT) and brown adipose tissue (BAT). C57BL/6 mice were exposed to PM_2.5 in a whole-body inhalational exposure system. After 10 weeks, the expression of clock-related genes exhibits more robust CR in BAT than WAT, with the acrophase of PER2 in both types of adipose tissue being significantly decreased at ZT12 and Bmal1 increased at ZT0/24 in WAT in response to PM_2.5 exposure. In addition, both CR pattern and expression levels of Sirt1 got significantly inhibited by PM_2.5 exposure in WAT, accompanied with adipose dysfunction evidenced by inhibited pattern and expression levels of adipokines at the same ZT time points. Finally, a similar phase right shift from ZT4 to ZT12 in both Sirt3 and Ucp1 in BAT was induced by PM_2.5 exposure. These findings indicate that disruption of the CR in adipose tissues could be an important way by which PM_2.5 exposure induces metabolic disorder and provide potential targets for further investigation.

Resveratrol improves glucose uptake in insulin-resistant adipocytes via Sirt1

Insulin resistance serves as "common soil" for promoting the development of metabolic diseases; however, the precise pathological factors leading to insulin resistance are not well clarified. Resveratrol (Res) is a natural polyphenolic compound with anti-inflammatory and antioxidative effects. However, effects and mechanisms of Res on glucose metabolism in adipocytes remain largely unknown. In this study, we show Res treatment significantly increases glucose uptake in insulin-resistant 3T3-L1 adipocytes in vitro. Mechanistically, Res up-regulates the protein level of Sirt1 that improves insulin signaling pathway and promotes cellular membrane Glut4 accumulation. Meanwhile, Sirt1 enhances phosphorylation level of AMPK which elevates p-AKT level. Consequently, the transcription factor FOXO1 translocalizes from nucleus to cytoplasm where protein degradation occurs. Therefore, the gene expression of resistin, a direct transcriptional target of FOXO1, is reduced and insulin sensitivity is improved. Importantly, we recapitulate the similar pattern of related protein changes in epididymal adipose tissues of insulin-resistant mice after Res intervention in vivo, reinforcing the hypothesis of Res being involved in regulation of glucose uptake via Sirt1-AMPK axis. Our findings clarify the beneficial effects of Res on glucose transportation in insulin-resistant adipocytes and involved pathway including Sirt1-AMPK, suggesting its potential therapeutic application in the treatment or prevention of insulin-resistance-related metabolic symptoms.

Silencing FoxO1 expression promotes expression of high molecular weight adiponectin in 3T3-L1 cells

AIM

To observe the effect of fork head box transcription factor O1 (FoxO1) gene silencing on the expression of disulfide-bond A oxidoreductase-like protein (DsbA-L) and high molecular weight (HMW) adiponectin.

METHODS

Lentiviral vector carrying short hairpin RNAs (shRNAs) targeting the FoxO1 gene was constructed, and the shRNA with the highest inhibition of FoxO1 expression (shRNA-FoxO1) in 3T3-L1 fat cells was selected by real-time quantitative PCR and Western blot and used for subsequent experiments. The expression of DsbA-L and HMW adiponectin in 3T3-L1 fat cells was determined by Western blot after infection with lentiviral vector carrying shRNA-FoxO1.

RESULTS

The lentiviral vector carrying the shRNA-FoxO1 had the most significant effect on the expression of FoxO1 in 3T3-L1 cells. The inhibition rate reached over 60%, and the relative expression levels of FoxO1 gene between the shRNA-FoxO1 and control groups were 0.37 ± 0.05 and 1.04 ± 0.04, respectively (P < 0.001). Western blot analysis showed that compared with the control group, the expression of FoxO1 was significantly inhibited (1.02 ± 0.08 vs 0.38 ± 0.08, P < 0.001), but the expression of DsbA-L and HMW adiponectin was significantly increased (0.28 ± 0.06 vs 0.53 ± 0.07, P = 0.009; 0.05 ± 0.02 vs 0.11 ± 0.03, P = 0.043) in the shRNA-FoxO1 group.

CONCLUSION

In 3T3-L1 cells, silencing FoxO1 gene promotes the expression of DsbA-L and HMW adiponectin.

Resistin's, obesity and insulin resistance: the continuing disconnect between rodents and humans

PURPOSE

This review aimed to discuss the conflicting findings from resistin research in rodents and humans as well as recent advances in our understanding of resistin's role in obesity and insulin resistance.

METHODS

A comprehensive review and synthesis of resistin's role in obesity and insulin resistance as well as conflicting findings from resistin research in rodents and humans.

RESULTS

In rodents, resistin is increased in high-fat/high-carbohydrate-fed, obese states characterized by impaired glucose uptake and insulin sensitivity. Resistin plays a causative role in the development of insulin resistance in rodents via 5' AMP-activated protein kinase (AMPK)-dependent and AMPK-independent suppressor of cytokine signaling-3 (SOCS-3) signaling. In contrast to rodents, human resistin is primarily secreted by peripheral-blood mononuclear cells (PBMCs) as opposed to white adipocytes. Circulating resistin levels have been positively associated with central/visceral obesity (but not BMI) as well as insulin resistance, while other studies show no such association. Human resistin has a role in pro-inflammatory processes that have been conclusively associated with obesity and insulin resistance. PBMCs, as well as vascular cells, have been identified as the primary targets of resistin's pro-inflammatory activity via nuclear factor-κB (NF-κB, p50/p65) and other signaling pathways.

CONCLUSION

Mounting evidence reveals a continuing disconnect between resistin's role in rodents and humans due to significant differences between these two species with respect to resistin's gene and protein structure, differential gene regulation, tissue-specific distribution, and insulin resistance induction as well as a paucity of evidence regarding the resistin receptor and downstream signaling mechanisms of action.

Green tea (-)-epigallocatechin gallate inhibits the growth of human villous trophoblasts via the ERK, p38, AMP-activated protein kinase, and protein kinase B pathways

Green tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been reported to circulate in the placenta of animals and blood of humans after consumption. Whether EGCG regulates activity of human villous trophoblasts (HVT) is unknown. This study investigated the pathways involved in EGCG modulation of trophoblast mitogenesis. EGCG inhibited trophoblast proliferation in a dose-dependent and time-dependent manner, as indicated by the number of cells and incorporation of bromodeoxyuridine (BrdU). EGCG was more effective than other green tea catechins in inhibiting cell growth. EGCG also increased the phosphorylation of the MAPK pathway proteins, ERK1/2, and p38, but not JNK. Furthermore, EGCG had no effects on the total amounts of ERK1/2, p38 MAPK, and JNK proteins. This suggests that EGCG selectively affects particular MAPK subfamilies. Pretreatment with specific inhibitors of ERK1/2, p38 MAPK, and AMP-activated protein kinase (AMPK) antagonized EGCG-induced decreases in both cell number and BrdU incorporation. These inhibitors also blocked EGCG-induced increases in the levels of phospho-ERK1/2, phospho-p38, and phospho-AMPK proteins, respectively. Moreover, EGCG was similar to the phosphatidylinositol 3-kinase inhibitors wortmannin and LY-294002 to decrease protein kinase B (AKT) phosphorylation, cell number, and BrdU incorporation. These data imply that EGCG inhibits the growth of HVT through the ERK, p38, AMPK, and AKT pathways.