• Title, Summary, Keyword: Leptin

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Cloning and Expression of the Duck Leptin Gene and the Effect of Leptin on Food Intake and Fatty Deposition in Mice

  • Dai, Han Chuan;Long, Liang Qi;Zhang, Xiao Wei;Zhang, Wei Min;Wu, Xiao Xiong
    • Asian-Australasian Journal of Animal Sciences
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    • v.20 no.6
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    • pp.850-855
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    • 2007
  • Leptin is the adipocyte-specific product of the obese gene and plays a major role in food intake and energy metabolism. Leptin research was mainly focused on mammalian species, but understanding of leptin and its function in poultry is very poor. In this study, the duck leptin gene was amplified using the reverse transcription-polymerase chain reaction (RT-PCR) from duck liver RNA. The cDNA fragment was inserted into the pET-28a expression vector, and the resulting plasmid was expressed in Escherichia coli BL21 (DE3). Experimental mice were given an intraperitoneal injection of 10 mg/kg leptin dissolved in phosphate buffered saline (PBS), while the control mice were injected with PBS. The effect of leptin on food intake, body weight and fatty deposition in mice was detected. Sequence analysis revealed that duck leptin had a length of 438 nucleotides which encoded a peptide with 146 amino acid residues. The sequence shares highly homology to other animals. The coding sequence of duck leptin was 84 and 86% identical to human and pig leptin nucleotides sequence. Highest identity was with the rat coding sequence (95%). The identity of the amino acid sequence was 84, 82 and 96% respectively compared to that of the human, pig and rat. Results of SDS-PAGE analysis indicated that a fusion protein was specifically expressed in E. coli BL21 (DE3). The purified product was found to be biologically active during tests. Continuous administration of recombinant duck leptin inhibited food intake. Despite the decrease of food intake, leptin significantly induced body weight and fatty deposition. These changes were accompanied by a significant down-secretion of plasma glucose, cholesterol, triglyceride and insulin levels in mice. The observations provide evidence for an inhibitory effect of leptin in the regulation of food intake and for a potential role of duck leptin in the regulation of lipogenesis.

Production of Leptin in E. coli and Its Effect on Glucose and Acetate Transport and Expression of Uncoupling Protein-2 Gene in Adipose Tissues of Korean Cattle (Hanwoo)

  • Kim, K.S.;Baik, M.G.
    • Asian-Australasian Journal of Animal Sciences
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    • v.17 no.8
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    • pp.1062-1068
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    • 2004
  • Leptin has a major role in the regulation of food intake and energy homeostasis. In addition, leptin participates in many physiological functions including regulation of lipid metabolism. Bovine recombinant leptin protein was produced in E. coli cells in order to understand function of leptin in the regulation of lipid metabolism. The leptin expression vector was constructed in pGEX-4T-3 vector and transformed into E. coli BL21 cells. Expression of the GST-leptin fusion protein was induced with IPTG. The fusion protein was purified using glutathione sepharose 4B batch method, and the recombinant leptin was eluted after thrombin protease digestion. The effect of leptin on glucose transport was examined in the differentiated adipocytes of 3T3-L1 cells. Leptin had no effect on basal and insulin-stimulated glucose transport in 3T3-L1 cells (p>0.05). Effect of recombinant leptin on glucose and acetate transport was examined in adipose tissues of Korean cattle (Hanwoo). Insulin stimulated glucose transport in both intramuscular and subcutaneous adipose tissues (p<0.05), but leptin did not affect glucose transport in both adipose tissues (p>0.05). Insulin stimulated acetate transport in bovine adipose tissues (p<0.05), but leptin did not affect acetate transport (p>0.05). Northern and RT-PCR analyses showed that mRNA levels of uncoupling protein-2 were increased by leptin treatment in 3T3-L1 cells without statistical difference (p>0.05). In conclusion, bovine recombinant leptin did not affect glucose and acetate transport in both 3T3-L1 adipocytes and bovine adipose tissues, while it stimulates UCP-2 mRNA expression in 3T3-L1 cells.

Inhibition of Leptin and Leptin Receptor Gene Expression by Silibinin-Curcumin Combination

  • Nejati-Koshki, Kazem;Akbarzadeh, Abolfazl;Pourhasan-Moghaddam, Mohammad;Abhari, Alireza;Dariushnejad, Hassan
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.11
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    • pp.6595-6599
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    • 2013
  • Leptin and its receptor are involved in breast carcinogenesis as mitogenic factors. Therefore, they could be considered as targets for breast cancer therapy. Expression of the leptin receptor gene could be modulated by leptin secretion. Silibinin and curcumin are herbal compounds with anti-cancer activity against breast cancer. The aim of this study was to assess their potential to inhibit of expression of the leptin gene and its receptor and leptin secretion. Cytotoxic effects of the two agents on combination on T47D breast cancer cells was investigated by MTT assay test after 24h treatment. With different concentrations the levels of leptin, leptin receptor genes expression were measured by reverse-transcription real-time PCR. Amount of secreted leptin in the culture medium was determined by ELISA. Data were statistically analyzed by one-way ANOVA test. The silibinin and curcumin combination inhibited growth of T47D cells in a dose dependent manner. There were also significant difference between control and treated cells in leptin expression and the quantity of secreted leptin with a relative decrease in leptin receptor expression. In conclusion, these herbal compounds inhibit the expression and secretion of leptin and it could probably be used as drug candidates for breast cancer therapy through leptin targeting in the future.

Metformin Enhances Leptin Sensitivity in Aged Rats

  • Kim, Sae-Rom;Park, So-Young;Kim, Jong-Yeon;Kim, Yong-Woon
    • The Korean Journal of Physiology and Pharmacology
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    • v.10 no.1
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    • pp.1-6
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    • 2006
  • To evaluate whether metformin restores leptin sensitivity in aged rats with leptin resistance, we measured leptin sensitivity in aged (2 year old) and adult (5 month old) rats after 4 weeks of treatment with metformin (300 mg/kg/D, mixing in drinking water), by measuring food intake, body weight and visceral fat losing effects. Leptin ($15{\mu}g/D$) was administered by intracerobroventricular (i.c.v.) infusion through osmotic minipump for 1 week. Metformin treatment decreased body weight and daily food intake in both adult and aged rats compared with their control rats, however, these effects were more prominent in aged rats than in adult rats. Anorexic and fat losing responses following i.c.v. leptin were attenuated in aged rats compared to adult rats. However, these responses of aged rats to leptin were restored by metformin treatment. Moreover, serum concentration of leptin in aged rats was significantly decreased by combined treatment with metformin and leptin. These results suggest that metformin enhances leptin sensitivity in aged rat model, and that combination therapy with metformin and leptin would be helpful for treatment of aging-associated obesity.

p53 signaling is involved in leptin-induced growth of hepatic and breast cancer cells

  • Shrestha, Mohan;Park, Pil-Hoon
    • The Korean Journal of Physiology and Pharmacology
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    • v.20 no.5
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    • pp.487-498
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    • 2016
  • Leptin, an adipokine predominantly produced from adipose tissue, is well known to induce tumor growth. However, underlying molecular mechanisms are not established yet. While p53 has long been well recognized as a potent tumor suppressor gene, accumulating evidence has also indicated its potential role in growth and survival of cancer cells depending on experimental environments. In the present study, we examined if p53 signaling is implicated in leptin-induced growth of cancer cells. Herein, we demonstrated that leptin treatment significantly increased p53 protein expression in both hepatic (HepG2) and breast (MCF-7) cancer cells without significant effect on mRNA expression. Enhanced p53 expression by leptin was mediated via modulation of ubiquitination, in particular ubiquitin specific protease 2 (USP2)-dependent manner. Furthermore, gene silencing of p53 by small interfering RNA (siRNA) suppressed leptin-induced growth of hepatic and breast cancer cells, indicating the role of p53 signaling in tumor growth by leptin. In addition, we also showed that knockdown of p53 restored suppression of caspase-3 activity by leptin through modulating Bax expression and prevented leptin-induced cell cycle progression, implying the involvement of p53 signaling in the regulation of both apoptosis and cell cycle progression in cancer cells treated with leptin. Taken together, the results in the present study demonstrated the potential role of p53 signaling in leptin-induced tumor growth.

Expression of OB-R, Regulation of Mitogen Activated Protein Kinase Activity and Maturation by Leptin in Mouse Oocytes (생쥐 난자 및 초기배아에서 Leptin 수용체 발현 및 Leptin에 의한 Mitogen Activated protein Kinase 활성의 조절 및 난자의 성숙 조절)

  • Kang, Byung-Moon;Han, Hyun-Joo;Seo, Hye-Young;Hong, Suk-Ho;Gye, Myung-Chan
    • Clinical and Experimental Reproductive Medicine
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    • v.28 no.2
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    • pp.111-120
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    • 2001
  • Objective: To verify the expression of leptin receptor (OB-R) in oocytes and preimplantation embryos, the involvement of mitogen activated protein kinase (MAPK or Erk1/2) in the leptin signaling, and effect of leptin on the oocyte maturation in mice. Method: RT-PCR analysis of OB-R was conducted in germinal vesicle (GV)-intact and MII stage oocytes, and 1, 2, 8-cell embryos and blastocysts. Germinal vesicle breakdown (GVB), polar body extrusion, monitored in the presence or absence of leptin ($1{\mu}M$). Following the leptin treatment, temporal changes in MAPK activity were verified by immunoprecipitation and in vitro kinase assay in MII oocytes. Results: The expression of OB-R mRNA was found in GV and MII oocyte but not in the embryos. MAPK activity of the MII oocytes was significantly increased by brief incubation in the HTF supplemented with leptin ($1{\mu}M$). Priming of PD098059, a MEK inhibitor to leptin treatment attenuated the activation of MAPK by leptin in MII oocytes. Following 24 hrs of culture of the GV oocytes, leptin significant increased the GVB and 1 st polar body extrusion. Conclusion: This result suggested that functional interaction between leptin and OB-R resulted in potentiation of MAPK (Erk1/2) activity in MII oocytes through MEK activation and that leptin might be a local regulator of meiotic maturation of the mouse oocytes.

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Effect of Leptin on the Expression of Lipopolysaccharide-Induced Chemokine KC mRNA in the Mouse Peritoneal Macrophages

  • Lee, Dong-Eun;Kim, Hyo-Young;Song, In-Hwan;Kim, Sung-Kwang;Seul, Jung-Hyun;Kim, Hee-Sun
    • Journal of Microbiology and Biotechnology
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    • v.14 no.4
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    • pp.722-729
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    • 2004
  • Leptin is an adipocyte-secreted hormone and its plasma levels correlate with total body fat mass, however, it also plays a regulatory role in immunity, inflammation, and hematopoiesis. Chemokine is known as a chemoattractant cytokine in inflammatory reaction, but its role in leptin reaction has not been well studied. In this study, the direct effect of leptin on the expression of chemokine mRNAs and lipopolysaccharide (LPS)-induced chemokine KC mRNA in mouse peritoneal macrophages was investigated. Leptin did not induce the expression of lymphotactin, RANTES, eotaxin, MIP-1$\beta$, MIP-1$\alpha$, MIP-2, MCP-1, IP-10, TCA-3, and KC mRNA in mouse peritoneal macrophages, and had no direct effect on the expression of these LPS-induced chemokine mRNAs except KC mRNA. The synergistic effect of leptin on the expression of LPS-induced KC mRNA occurred late in the time course of response to LPS. The increased expressions of Ob-Rb mRNA and leptin receptor protein were detected during the LPS treatment. Leptin produced a substantial increase in the stability of the LPS-induced KC mRNA, and the synergistic effect of leptin on LPS-induced KC mRNA expression was further augmented by cycloheximide (CHX). Pyrrolidine dithiocarbamate (PDTC) did not block the synergistic effect of leptin on LPS-induced KC mRNA expression in mouse peritoneal macrophages. These data suggest that although leptin has no direct effect on the expression of lymphotactin, RANTES, eotaxin, MIP-1$\beta$, MIP-1$\alpha$, MIP-2, MCP-1, IP-10, TCA-3, and KC mRNA in mouse peritoneal macrophages, the synergistic effect of leptin on the expression of LPS-induced KC mRNA has the possibility that LPS might induce the expression of the Ob-Rb receptor or an unknown gene(s) that sensitizes macrophages to the synergistic function of leptin. Therefore, further studies are necessary to examine leptin as a regulatory factor of chemokine production.

A Study on Serum Leptin Values by Elisa Method in Children (ELISA법으로 측정한 소아 혈중 LEPTIN 치에 관한 연구)

  • Song, Soo-Ho;Chung, Young-Hun
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.3 no.2
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    • pp.175-180
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    • 2000
  • Purpose: Leptin is an adipocyte-derived blood-borne satiety factor that acts on its cognate leptin receptor in the hypothalamus, thereby regulating food intake and energy expenditure. We measured the leptin concentrations in serum of normal and obese children with human leptin ELISA kit, unlike previous study with leptin RIA kit and investigated the relationship between leptin concentrations and body mass index, gender, and age. Methods: We measured serum concentrations of leptin in 67 children who were visited to the Department of Pediatrics, Chungnam National University Hospital during the period of 5 months from February, 1999 to June, 1999. Height, weight, obesity index, and body mass index were measured in 67 subjects. Leptin values in serum were measured by sandwich ELISA method. Data analysis was done according to the obesity, body mass index, gender and age. Results: The mean concentration of leptin was $7.69{\pm}8.83\;ng/ml$ in normal children group and $36.34{\pm}18.57\;ng/ml$ in obese group. Serum leptin concentrations were significant correlation with the body mass index (p<0.01). Serum leptin concentration was significant higher in the group of over 10 years of age (p<0.01). Leptin levels showed no significant difference by gender. Conclusion: Serum leptin levels were significantly higher in obesity group than in control one, and they were correlated with body mass index and age. Measurements of leptin value by sandwich ELISA method are very useful and easily applicable to determine obesity.

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Correlations of Leptin, Adiponectin and Leptin/Adiponectin Ratio with Metabolic Disorders in the Childhood Obesity (소아 비만에서 Leptin, Adiponectin 및 Leptin/Adiponectin Ratio와 대사 장애의 연관성에 관한 연구)

  • Cho, Sung Jong;Kim, Eun Young;Moon, Kyung Rye
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.9 no.1
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    • pp.48-57
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    • 2006
  • Purpose: To investigate the correlation of the serum leptin, adiponectin, and leptin/adiponectin ratio with metabolic disorders in the childhood obesity. Methods: Fifty children (25 obese and 25 non-obese) were recruited in the pediatric outpatient clinic of Chosun University Hospital from January 1st to June 30th 2005. Adiponectin, leptin, anthropometric parameters, glucose, LDL-cholesterol, HDL-cholesterol, total cholesterol, triglyceride, and insulin levels were measured. The correlations of leptin and adiponectin levels with anthropometric parameters, glucose, insulin and lipids were analyzed by Pearson's correlation coefficients. Results: Insulin and leptin levels of the obese group were significantly higher than those of the non-obese group (p<0.05, p<0.001 respectively). HDL-cholesterol and adiponectin levels of the obese group were significantly lower than those of the non-obese group (p<0.005, p<0.05 respectively). In the obese group, leptin level was positively correlated with BMI and the percentage of body fat, but negatively correlated with adiponectin level. Moreover, adiponectin level of the obese group was negatively correlated with BMI and the percentage of body fat, but positively correlated with leptin level. In the non-obese group, only insulin level was positively correlated with adiponectin. In the obese group, leptin/adiponectin ratio was positively correlated with the percentage of body fat and leptin level. Also, leptin/adiponectin ratio was positively correlated with BMI and the percentage of body fat in the non-obese group. Conclusion: Leptin, adiponectin, and leptin/adiponectin ratio did not appear to have a major role linking various metabolic disorders in the childhood obesity, even though they were strongly associated with obesity indices. Also, leptin/adiponectin ratio was associated with obesity indices even in non-obese children.

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Twenty-four-hour Variation of Plasma Leptin Concentration and Pulsatile Leptin Secretion in Cattle

  • Kawakita, Y.;Abe, H.;Hodate, K.
    • Asian-Australasian Journal of Animal Sciences
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    • v.14 no.9
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    • pp.1209-1215
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    • 2001
  • We conducted this study to investigate 24 h leptin profiles and to ascertain whether leptin secretion occurs in a pulsatile manner in cattle. Plasma leptin concentrations were measured every 10 min for 24 h in five Holstein steers aged 10 months. Simultaneously, feeding behavior was recorded every 5 min during this experiment. In two of the five cattle, leptin showed diurnal rhythmicity, which could be described by a cosine, with peaks between 15:00 and 16:00 and nadirs at around midnight. Pulsatile leptin release was quantified by model-free Cluster analysis. Plasma leptin showed a pulsatile pattern in all cattle, with an average number of pulses at 15 peaks/24 h. The daily number of pulses was not related to total time spent eating, ruminating or chewing. However, when divided into six 4 h time intervals, time spent ruminating was positively related with pulse number (p=0.05) in cattle showing no diurnal plasma leptin variation. These results suggest that cattle may have unique diurnal variation and pulsatile patterns of plasma leptin, differing from those of monogastric animals.