Resistin mRNA Levels Research Articles

Resistin Expression Is Associated With Interstitial Lung Disease in Dermatomyositis.

ObjectiveIn the current study, we aimed to assess resistin mRNA levels in the peripheral blood mononuclear cells (PBMCs) of dermatomyositis patients with interstitial lung disease (DM-ILD) and their correlation with disease activity.MethodsWe detected resistin mRNA levels in the PBMCs of 37 DM-ILD, 8 DM patients without ILD, and 19 healthy control (HC) subjects by performing quantitative reverse transcription real-time polymerase chain reaction analysis. Associations between resistin expression levels and major clinical manifestations, laboratory examinations, and disease activity were also analyzed. In addition, resistin expression in lung specimens from patients with DM-ILD was examined via immunohistochemistry and immunofluorescence.ResultsResistin mRNA levels in PBMCs were significantly higher in DM-ILD than that in DM patients without ILD and HCs (p = 0.043, 0.014, respectively). Among these DM-ILD patients, the resistin levels were significantly elevated in those with rapidly progressive ILD than in those with chronic ILD (p = 0.012). The resistin mRNA levels in DM-ILD positively correlated with serum alanine aminotransferase (r = 0.476, p = 0.003), aspartate aminotransferase (r = 0.488, p = 0.002), lactate dehydrogenase (r = 0.397, p = 0.014), C-reactive protein (r = 0.423, p = 0.008), ferritin (r = 0.468, p = 0.003), carcinoembryonic antigen (r = 0.416, p = 0.011), carbohydrate antigen 125 (r = 0.332, p = 0.047), interleukin-18 (r = 0.600, p < 0.001), and lung visual analog scale values (r = 0.326, p = 0.048), but negatively correlated with the diffusing capacity of carbon monoxide (DLco)% (r = −0.447, p = 0.041). Immunohistochemical analysis of resistin showed its elevated expression in the macrophages, alveolar epithelial cells, and weak fibrotic lesions from patients with DM-ILD. Immunofluorescence staining confirmed CD68+ macrophages co-express resistin.ConclusionsResistin levels were increased in patients with DM-ILD and associated with disease activity and ILD severity. Therefore, resistin may participate in the pathogenesis of DM-ILD and may act as a useful biomarker.

Increased gene expression of resistin and CD36 in peripheral blood mononuclear cells is associated with hypercholesterolemia in patients with obstructive sleep apnea

Background and Aims: Obstructive sleep apnea (OSA) is associated with increased risk of cardiovascular disease. Resistin is recognized as a potent proinflammatory cytokine that is able to influence atherosclerotic plaque progression through several mechanisms. Resistin facilitates formation of foam cells through upregulation of CD36 scavenger receptor and increased uptake of oxidized low density lipoprotein. Its proinflammatory effects are mainly exerted via adenylate cyclase-associated protein 1 (CAP1). The aim of this study was to investigate if resistin, CAP1 and CD36 mRNA levels in peripheral blood mononuclear cells (PBMCs) are associated with hypercholesterolemia in patients with obstructive sleep apnea.

MiR-625 Inhibits Tumor Cell Invasion, Migration and EMT by Negatively Regulating the Expression of Resistin in Non-Small Cell Lung.

PurposeTo investigate the role of miR-625 on the invasion, migration, and epithelial–mesenchymal transition (EMT) of non-small cell lung carcinoma (NSCLC) cells, and the related mechanisms.Materials and MethodsThe expression levels of miR-625 and Resistin mRNA in 80 pairs of NSCLC and para-cancerous lung tissues were analyzed by RT-PCR. The relationship between miR-625 and Resistin was predicted by bioinformatics and verified by a dual-luciferase gene reporter assay. NSCLC cells were transfected with Resistin plasmids, si-Resistin plasmids, miR-625 mimics, or miR-625 inhibitors, and proliferation, invasion, and migration were determined by CCK-8, Transwell, and wound scratch assays, respectively. EMT-related proteins were determined by Western blot assay. A xenograft model of NSCLC was established in nude mice to validate the in vitro findings.ResultsMiR-625 was significantly downregulated in NSCLC tissue compared to paired para-cancerous lung tissues, while Resistin was markedly increased in tumor tissue. The expression levels of miR-625 and Resistin were negatively correlated in NSCLC tissues, and high levels of Resistin correlated with greater tumor differentiation, more advanced clinical staging, and lymph node metastasis. Furthermore, Resistin was a target gene of miR-625, and the latter downregulated Resistin to inhibit the EMT, proliferation, invasion, and migration of NSCLC cells in vitro, likely via the PI3K/AKT/Snail signaling pathway. Finally, miR-625 also inhibited the tumorigenic effect of NSCLC cells in vivo by downregulating Resistin.ConclusionMiR-625 acts as a tumor suppressor in NSCLC and inhibits tumor cell invasion and metastasis by blocking the Resistin/PI3K/AKT/Snail pathway and by decreasing EMT.

Relationships between placental adiponectin, leptin, visfatin and resistin and birthweight in cattle.

Adipokines can affect intrauterine development while calf birthweight (CBW) is a breeding standard of calves, which reflects the status of fetal intrauterine development. To explore the correlation between placental adipokines and CBW, 54 healthy Chinese Holstein cows were used in the present study. The cows were grouped according to the CBW of their calves. Placentas were collected immediately after delivery and enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction were used to detect the placental expression levels of adiponectin, leptin, visfatin and resistin. Our results show that the mRNA transcription and blood placental content of adiponectin, leptin, visfatin and resistin increased with increasing CBW. The analysis showed that the mRNA transcription levels of placental adiponectin, leptin and resistin were positively correlated with CBW. The mRNA and protein expression levels of adiponectin, leptin and visfatin between the three groups were significantly correlated. Placental resistin mRNA levels correlated positively with adiponectin mRNA, but not leptin or visfatin. The protein expression levels of resistin were significantly positively correlated with those of adiponectin, leptin and visfatin. These results suggest that placental adipokines play important roles in regulating calf intrauterine growth.

Association among resistin, adenylate cyclase-associated protein 1 and high-density lipoprotein cholesterol in patients with colorectal cancer: a multi-marker approach, as a hallmark of innovative predictive, preventive, and personalized medicine

Elevated concentrations of resistin have been reported in colorectal cancer (CRC), but its interactions with adenylate cyclase-associated protein 1 (CAP-1) are largely unexplored. We investigated resistin plasma concentration, peripheral blood mononuclear cells (PBMCs) resistin messenger ribonucleic acid (mRNA), and CAP-1 mRNA levels in CRC patients, as well as the impact of resistin gene polymorphism rs1862513 on the examined markers. We also explored associations of resistin with high-density lipoprotein cholesterol (HDL-C) and predictive potential of our parameters for CRC. Eighty-six patients with CRC and 75 healthy adults were included. Commercial ELISA kit was used for obtaining resistin's concentrations, while polymerase chain reaction (PCR) method was applied for evaluation of resistin and CAP-1 mRNA levels and rs1862513 polymorphism. Plasma resistin and CAP-1 mRNA levels were higher in CRC patients (p < 0.001 and p < 0.05, respectively), while resistin mRNA levels were lower (p < 0.001). Negative association existed among plasma resistin and HDL-C concentrations (ρ = - 0.280; p < 0.05). A model including age, body-mass index, HDL-C, low-density lipoprotein cholesterol (LDL-C), and plasma resistin concentrations as independent predictors of CRC showed very good diagnostic accuracy (AUC = 0.898). We found no associations of rs1862513 with the examined markers. Our study demonstrated increased plasma resistin and CAP-1 mRNA levels, implying their possible interaction in CRC. The association among plasma resistin and HDL-C might indicate that HDL-C is involved in alterations of resistin's secretion process. As a hallmark of personalized medicine, multi-marker approach in determination of resistin-related parameters might be useful for prediction and prevention of CRC development.

SAT-334 Proinflammatory Cytokines Modulate Resistin Expression in Breast Cancer Cells

Resistin is a proiflammatory adipokine produced by the white adipose tissue macrophages and adipocytes. Resistin expression is upregulated in breast cancer tissue and positively correlates with tumor stage, tumor size and lymph node metastasis. Previous studies found that resistin increases breast cancer invasiveness, stimulates epithelial to mesenchymal transition (EMT) and induces acquisition of cancer stem cell properties in breast cancer cells. Breast cancer cells express a variety of cytokines and their receptors, and resistin mRNA expression was previously detected in HCT-116 colorectal cancer cells. By using qRT-PCR analysis, we amplified resistin mRNA and compared its relative expression levels in a panel of breast cancer and breast non-carcinogenic cell lines, including MCF-7, T47D, BT474, HCC1806, MDA-MB-468, MDA-MB-231, and MCF-10A cells. We found that MCF-7, T47D, and HCC1806 cells express detectable levels of resistin mRNA. Using MCF-7 cells, we further investigated whether this expression can be modulated by treatment with different cytokines (resistin, TNFα, or TGFβ). Our results indicated that resistin (in concentration of 12.5 ng/ml), TNFα and TGFβ (in concentrations of 10 ng/ml) upregulated the expression of resistin mRNA in a time-dependent manner. In conclusion, we report that breast cancer cells express resistin mRNA, and that this expression is upregulated after treatment with resistin, TNFα, and TGFβ. To our best knowledge, this is the first study describing resistin mRNA expression in breast cancer cells and its alteration by proinflammatory factors. Further experiments are in progress.

The effects of quercetin supplementation on metabolic and hormonal parameters as well as plasma concentration and gene expression of resistin in overweight or obese women with polycystic ovary syndrome.

The aim of this study was to investigate the effect of quercetin on metabolic and hormonal parameters as well as plasma concentration and gene expression of resistin in overweight or obese women with polycystic ovary syndrome (PCOS). In this randomized, double-blind, placebo-controlled trial, 78 overweight or obese women (25≤BMI≤40kg/m2 , 20-40years) with PCOS were recruited. Patients were randomized to receive 1,000mg/day quercetin or placebo for 12weeks. Resistin plasma concentration and gene expression in peripheral blood mononuclear cells, parameters of glucose homeostasis, circulatory testosterone, luteinizing hormone (LH), and sex hormone-binding globulin, and anthropometries were assessed at baseline and at the end of the study. Following supplementation, quercetin significantly decreased resistin concentration (2.07±0.23 vs. 2.88±0.40ng/ml, p<0.001) and mRNA level (0.64±0.58 vs. 1±0.56 fold change, p=0.008), compared with placebo group. Moreover, testosterone (0.72±0.15 vs. 0.76±0.12ng/ml, p=0.001) and LH (8.05±2.88 vs. 8.77±1.99 mIU/ml, p=0.035) concentrations were significantly lower in quercetin compared with placebo group. Fasting blood glucose (p<0.001), insulin (p=0.02), and homeostatic model assessment of insulin resistance (p=0.009) decreased within the quercetin group; however, no significant differences were observed compared with the placebo group (p=0.074, p=0.226, p=0.22, respectively). Quercetin supplementation decreased resistin plasma levels and gene expression, and testosterone and LH concentration in overweight or obese women with PCOS.

Effects of SCFA on the DNA methylation pattern of adiponectin and resistin in high-fat-diet-induced obese male mice.

Specific adipokines, such as adiponectin and resistin, are secreted from adipose tissue and are associated with the development of obesity. Supplementation of dietary SCFA can prevent and reverse high-fat-diet (HFD)-induced obesity. However, it is not clear whether SCFA ameliorate abnormal expression of adiponectin and resistin in the obese state. The aim of this study was to investigate the effects of SCFA on adiponectin and resistin's expressions in diet-induced obese mice, as well as the potential mechanisms associated with DNA methylation. C57BL/6J male mice were fed for 16 weeks with five types of HFD (34·9 % fat by wt., 60 % kJ) - a control HFD and four HFD with acetate (HFD-A), propionate (HFD-P), butyrate (HFD-B) and their admixture (HFD-SCFA). Meanwhile, a low-fat diet (4·3 % fat by wt., 10 % kJ) was used as the control group. The reduced mRNA levels of adiponectin and resistin in the adipose tissue of the HFD-fed mice were significantly reversed by dietary supplementation of acetate, propionate, butyrate or their admixture to the HFD. Moreover, the expressional changes of adiponectin and resistin induced by SCFA were associated with alterations in DNA methylation at their promoters, which was mediated by reducing the expressions of enzyme-catalysed DNA methyltransferase (DNMT1, 3a, 3b) and the methyl-CpG-binding domain protein 2 (MBD2) and suppressing the binding of these enzymes to the promoters of adiponectin and resistin. Our results indicate that SCFA may correct aberrant expressions of adiponectin and resistin in obesity by epigenetic regulation.

Increased expression of resistin in ectopic endometrial tissue of women with endometriosis.

Inflammation is a key process in the establishment and progression of endometriosis. Resistin, an adipocytokine, has biological properties linked to immunologic functions, but its role in endometriosis is unclear. Resistin gene expression was examined in eutopic and ectopic endometrial tissues from women with (n=25) or without (n=25) endometriosis. Resistin mRNA and protein levels were determined in endometrial tissue using quantitative real-time reverse transcription PCR and Western blotting, following adipokine profiling arrays. Resistin protein was detected in human endometrial tissues using an adipokine array test. Resistin mRNA and protein levels were significantly higher in ectopic endometrial tissue of patients with endometriosis than in normal eutopic endometrial tissue. Our results indicate that resistin is differentially expressed in endometrial tissues from women with endometriosis and imply a role for resistin in endometriosis-associated pelvic inflammation.

Higher circulating resistin protein and PBMCs resistin mRNA levels are associated with increased prevalence of small dense LDL particles in coronary artery disease patients

Recent in vitro experiments have indicated that human resistin increases the number of lipoprotein particles secreted by the human hepatocytes and also influences their quality, in terms of generating more proatherogenic lipid particles. The aim of this study is to investigate associations of plasma resistin and peripheral blood mononuclear cells (PBMCs) resistin messenger RNA (mRNA) levels with different prevalence of small, dense low-density lipoprotein particles (sdLDL) in patients with indications for coronary angiography. This study included 65 patients requiring coronary angiography. There were 41 patients without significant stenosis and 24 patients with significant stenosis in at least one major coronary artery. Circulating resistin was measured by enzyme-linked immunosorbent assay; PBMC resistin mRNA was determined by real-time polymerase chain reaction. The LDL and high density lipoprotein subclasses were determined by gradient gel electrophoresis. Plasma resistin (P = 0.031) and PBMCs resistin mRNA (P = 0.004) were significantly higher in patients with proportion of sdLDL particles ≥ 50%, compared to the group with relative proportion of sdLDL particles < 50%. Plasma resistin correlated positively with creatinine (r = 0.456, P < 0.001) and resistin mRNA (r = 0.298, P = 0.014) but negatively with body mass index (r = -0.254, P = 0.034) and total cholesterol (r = -0.286, P = 0.021). Multiple linear regression analysis revealed LDL particle diameter as the only independent predictor of resistin mRNA (R(2) = 0.258; adjR(2) = 0.190). A significant association between resistin, both PBMCs mRNA and plasma protein, and the relative proportion of sdLDL particles in the circulation of coronary artery disease patients has been established, which implies that increased gene expression of resistin in PBMCs and higher resistin concentration in plasma are related to pro-atherogenic LDL particle phenotype.

Long-Lasting Consequences of Testosterone Exposure.

Evidence of reciprocal regulation of androgen signaling and obesity has been well documented (1, 2); it is clear that late gestational and early postnatal periods are most vulnerable to perturbation of these signaling pathways (3). Exposure to high caloric nutrition early in life causes significant changes in reproductive physiology which cannot be reversed by resumption of the normal diet. A maternal highfat diet produces prostatic hyperplasia in adult male and ovarian failure in adult female offspring (4, 5). Importantly, the embryo exposure to high caloric diet does not immediately activate androgen signaling and postnatal androgen surge in females does not immediately affect the weight; the effects of these stimuli are delayed until the organism is mature. Similarly, extensive experimental data indicate that the perturbations of hormonal balance during this developmental period have long-lasting effects not only on reproductive characteristics, including ovarian and neuroendocrine changes (6), but also changes in metabolic functions (7). The phenotype resembling human polycystic ovarian syndrome often associated with impaired insulin sensitivity and increased weight is observed in rodent females subjected to transient neonatal or prepubertal androgen treatment (8). The study published in this issue of Endocrinology by Jang et al (9) narrows down the critical period of sensitivity to exogenous androgen treatment in mice (9). Three temporal windows were used: within 24 hours after birth and at 3 or 6 weeks of age. A single injection of testosterone enanthate (TE) was used at every time point. Reproductive abnormalities were detected in adult females treated with androgens 24 hours after birth. No abnormalities were detected in females treated with TE at 3 or 6 weeks, suggesting that the developmental program at that stage was fully determined. An increase in blood testosterone concentration in newborn female pups partially mimicked the surge of testosterone in late neonatal/early postnatal period in male rodents (10). In males, the increase of testosterone at the end of pregnancy is required for completion of the full masculinization program (11), including scrotum development, testicular descent, and the substitution of fetal with adult Leydig cells (12). In females, the oocyte nest breakdown occurs, and the primordial follicle pool is established the early postnatal period (13). In this report, neonatal TE treatment caused reproductive abnormalities in adult females such as irregular cycling, anovulatory phenotype and increased ovarian weight. Surprisingly, despite clearly abnormal cystic ovaries and theabsenceof corpora lutea in treated females, no changes in estradiol, LH, or FSH levels and expression of estrogen receptors and and androgen receptor genes were detected. This distinguishes the results of these experiments from previous reports on androgen treatment in the prenatal or neonatal rodent females (14). It is possible that the much lower dose and significantly more stable derivative of testosterone used in the Jang et al study was responsible for these differences and that the signaling pathways in the target cells downstream from steroid receptors were affected. Additionally, metabolic parameters were changed in TE-treated females when compared with the vehicle-treated controls such as a greater body weight, including lean body and fat mass. When insulin resistance was compared in 30-week-old females injected with oil or TE 24 hours after birth, TE-treated females displayed significantly lower blood glucose levels in response to insulin injections as compared with controls. Increases in lipoprotein lipase and resistin mRNA levels, the key genes in lipogenic and lipolytic pathways in adipose tissues, were

Molecular cloning of feline resistin and the expression of resistin, leptin and adiponectin in the adipose tissue of normal and obese cats.

Resistin, one of the adipokines that has a cycteine-rich C-terminus, is considered to relate to the development of insulin resistance in rats. However, in cats, there is little knowledge regarding resistin. In this study, we cloned the feline resistin cDNA from adipose tissue by RT-PCR. The feline resistin clone contained an entire open reading frame encoding 107 amino acids that had 72.8%, 75.4%, 50.9% and 51.8% homology with bovine, human, mouse and rat homologues, respectively. In both subcutaneous and visceral adipose tissues, the transcription levels of feline resistin mRNA were significantly higher in obese cats than normal cats, and those of feline adiponectin mRNA were significantly lower in obese cats than normal cats. However, there was no difference in the expression of feline leptin between normal and obese cats. On the other hand, in both normal and obese cats, there were no significant differences in resistin, leptin and adiponectin mRNA levels between subcutaneous and visceral adipose tissues. In cats, the altered expression of resistin and adiponectin mRNA with obesity may contribute to the pathogenesis of insulin resistance and subsequent diabetes mellitus. In addition to feline adiponectin, the feline resistin cDNA clone obtained in this study will be useful for further investigation of the pathogenesis of obesity in cats.

Hyperglycemia-induced changes in resistin gene expression in white adipose tissue in piglets

Abstract Previous data strongly indicated that resistin, an adipocyte-derived signalling peptide, plays an important role in metabolism and glucose homeostasis. Thus, the aim of the present study was to examine changes in synthesis and concentration of resistin in white adipose tissue in response to hyperglycemia in piglets. In order to develop hyperglycemia, piglets (10-week-old, Polish Landrace fatteners, female) received intraperitoneal (ip) injection of 150 mg streptozotocin (HI, n=6) or 60 mg synthetic glucocorticoid (HII, n=6). An injection of NaCl physiological saline was used as a control (n=6). Plasma resistin level was significantly higher in HII group compared with the control, while no difference was observed in HI. In epicardial adipose tissue (EAT ) the resistin mRNA level significantly increased whereas the opposite effect was observed for omental fat tissue (OAT ) in both experimental groups. Additionally, the resistin concentration did not change in EAT ; however, it was decreased in omental adipose tissue in response to hyperglycemia. The results obtained indicate that activity of resistin strongly depends on glycemic status as well as adipose tissue localization.

The effects of ovariectomy and LPS-induced endotoxemia on resistin levels in female rats

Resistin is involved in the inflammatory response, as well as in insulin resistance. In rodents, resistin levels are partially regulated by ovarian hormones. Thus, ovariectomy-induced changes in resistin levels and their response to lipopolysaccharide (LPS)-induced septic stress were evaluated. Ovariectomized (OVX) rats exhibited higher serum resistin concentrations and visceral and subcutaneous white adipose tissue (WAT) resistin mRNA levels than sham-operated (sham) rats under the saline-injected (basal) conditions. The serum resistin levels of the gonadal intact male rats were higher than those of the sham rats, whereas the serum resistin levels of the male and OVX rats did not differ. In both the sham and OVX rats, the serum resistin concentration and the resistin mRNA levels of WAT were increased by LPS injection. At 24h after the LPS injection, no difference was detected in the serum resistin concentrations or WAT mRNA resistin levels between the sham and OVX rats. These results suggest that ovarian hormones partially regulate the basal resistin levels of female rats.

Association of resistin mrna and plasma levels with small dense ldl particles in coronary artery disease

Association of resistin mrna and plasma levels with small dense ldl particles in coronary artery disease

Effects of adipocyte-secreted factors on decidualized endometrial cells: modulation of endometrial receptivity in vitro.

Obesity is defined as an excessive accumulation of adipose tissue that may lead to health complications. Mounting evidence indicates that obesity has a negative impact on fertility. Yet, the link between adipose tissue biology and infertility remains unclear. We aimed to investigate the communication between the adipose tissue and the reproductive system and the importance of this cross talk for the development of a receptive endometrium. To that end, we generated an in vitro model with endometrial and adipocyte cell lines. Sexual hormones, progesterone and estradiol, were used to decidualize endometrial cells and sensitize adipocytes. Decidualization produced a simultaneous increase of adipokine receptors in endometrial cells paralleling changes in their receptivity status. Furthermore, sensitization of 3T3-L1 adipocytes increased mRNA levels of leptin and resistin and decreased the expression of adiponectin and chemerin levels. This was accompanied by increased isoproterenol-induced lipolysis and reduced insulin-stimulated glucose uptake. Lastly, conditioned culture medium of those sensitized adipocytes was used to feed endometrial cells. This treatment resulted in (i) upregulation of genes previously identified as positive regulators of endometrial receptivity, such as leukemia inhibitory factor and glutathione peroxidase 3, and (ii) downregulation of interleukin-15 and mucin1, both genes negatively related with endometrial receptivity. Our results indicate that the endocrine communication between adipose tissue and the reproductive system is bidirectional and stress the importance of the adipose tissue to modulate the reproductive fitness.

Increased protein and mRNA expression of resistin after dexamethasone administration.

Synthetic glucocorticoids such as dexamethasone are widely used to treat a variety of inflammatory and autoimmune conditions, but they may induce adverse events including hyperglycemia. To shed light on the effect and action mechanism of dexamethasone, we examined the alterations of gene expression levels caused by dexamethasone.Microarray analysis was performed on whole blood collected from 24 physically healthy subjects at baseline and after dexamethasone administration. The expression levels of resistin mRNA were found to be significantly increased after the dexamethasone administration. In a separate sample of 12 subjects, we examined plasma resistin protein levels and found that they were increased after dexamethasone administration. Furthermore, the plasma mRNA and protein levels of resistin were significantly higher in individuals who carried the A allele of RETN single nucleotide polymorphism rs3219175 than in those who did not carry the allele. There was no significant interaction between the genotype and dexamethasone administration. No significant correlation was found between plasma levels of cortisol and resistin. Consistent with previous studies, the genotype of RETN rs3219175 was a strong determinant of resistin levels. The present study showed that oral administration of dexamethasone increases the protein and mRNA levels of resistin irrespective of the rs3219175 genotype.

Reactive oxygen species up-regulates SOCS-3 in 3T3-L1 adipocytes

We investigated the effect of increased intracellular reactive oxygen species(ROS) on SOCS-3 expression in 3T3-L1 adipocytes. Increased intracellular ROS levels in 3T3-L1 adipocytes were achieved by two methods of exposure to H2O2 and the occurrence of oxidative stress in cells was assessed by flow cytometry . Expression of SOCS-3 mRNA and that of some adipokines were measured by real time PCR. The level of SOCS-3 protein was determined by western blot. The effect of the antioxidant alpha-lipoic acid was also investigated. Both the relatively mild increased intracellular ROS and the acute but transient increased ROS elevated the levels of SOCS-3 mRNA and protein in 3T3-L1 adipocytes, acompanied with elevated levels of TNF-α mRNA and resistin mRNA and the decreased levels of adiponectin mRNA and secretory adiponectin in culture medium. α-lipoic acid could attenuate the effects of ROS on 3T3-L1 adipocytes. We hypothesized that in mature 3T3-L1 adipocytes, SOCS-3 could be upregulated directly by the induction of increased intracellular ROS and to some extent which was up-regulated by adipokine modulation.

Endothelin‐1 stimulates resistin gene expression (LB756)

Resistin and endothelin (ET)‐1 have been reported to inhibit adipogenesis and regulate adipocyte insulin resistance, respectively. Although both hormones interact with each other, the exact signaling pathway of ET‐1 to act on resistin gene expression is still unknown. Using 3T3‐L1 adipocytes, we investigated the signaling pathways involved in ET‐1‐stimulated resistin gene expression. The upregulation of resistin mRNA expression by ET‐1 depends on concentration and timing. The concentration of ET‐1 that increased resistin mRNA levels by 100‐250% was approximately 100 nM for a range of 0.25~12 h of treatment. Treatment with actinomycin D blocked ET‐1‐increased resistin mRNA levels, suggesting that the effect of ET‐1 requires new mRNA synthesis. Treatment with an inhibitor of the ET type‐A receptor (ETAR), such as BQ610, but not with the ET type‐B receptor (ETBR) antagonist BQ788, blocked ET‐1‐increased the levels of resistin mRNA and phosphorylated levels of downstream signaling molecules such as ERK1/2, JNKs, AKT, and STAT3. Moreover, pretreatment of specific inhibitors of either ERK1/2 (U0126 and PD98059), JNKs (SP600125), PI3K/AKT (LY294002 and Wortmannin), or JAK2/STAT3 (AG490) prevented ET‐1‐increased levels of resistin mRNA and reduced the ET‐1‐stimulated phosphorylation of ERK1/2, JNKs, AKT, and STAT3, respectively. However, the p38 kinase antagonist SB203580 did not alter the effect of ET‐1. These results imply that ETAR, ERK1/2, JNKs, AKT, and JAK2, but not ETBR or p38, are necessary for the ET‐1 stimulation of resistin gene expression. In vivo observations that ET‐1 increased resistin mRNA and protein levels in subcutaneous and epididymal adipose tissues support the in vitro findings.

Resistin in Dairy Cows: Plasma Concentrations during Early Lactation, Expression and Potential Role in Adipose Tissue

Resistin is an adipokine that has been implicated in energy metabolism regulation in rodents but has been little studied in dairy cows. We determined plasma resistin concentrations in early lactation in dairy cows and investigated the levels of resistin mRNA and protein in adipose tissue and the phosphorylation of several components of insulin signaling pathways one week post partum (1 WPP) and at five months of gestation (5 MG). We detected resistin in mature bovine adipocytes and investigated the effect of recombinant bovine resistin on lipolysis in bovine adipose tissue explants. ELISA showed that plasma resistin concentration was low before calving, subsequently increasing and reaching a peak at 1 WPP, decreasing steadily thereafter to reach pre-calving levels at 6 WPP. Plasma resistin concentration was significantly positively correlated with plasma non esterified fatty acid (NEFA) levels and negatively with milk yield, dry matter intake and energy balance between WPP1 to WPP22. We showed, by quantitative RT-PCR and western blotting, that resistin mRNA and protein levels in adipose tissue were higher at WPP1 than at 5 MG. The level of phosphorylation of several early and downstream insulin signaling components (IRβ, IRS-1, IRS-2, Akt, MAPK ERK1/2, P70S6K and S6) in adipose tissue was also lower at 1 WPP than at 5 MG. Finally, we showed that recombinant bovine resistin increased the release of glycerol and mRNA levels for ATGL (adipose triglyceride lipase) and HSL (hormone-sensitive lipase) in adipose tissue explants. Overall, resistin levels were high in the plasma and adipose tissue and were positively correlated with NEFA levels after calving. Resistin is expressed in bovine mature adipocytes and promotes lipid mobilization in adipose explants in vitro.