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Abstract
PURPOSE OF REVIEW In the USA, 8-10 million people are morbidly obese, which is associated with a high frequency of comorbidities. The most effective treatment is surgery. Of around 180,000 bariatric operations performed in 2005, 80% were Roux-en-Y gastric bypass, consisting of a small gastric pouch to minimize food intake and a Roux-en-Y of distal small bowel bypassing the upper gastrointestinal tract. The precise mechanisms whereby Roux-en-Y gastric bypass achieves sustained weight loss remain unknown. To gain insight into the catabolic events of sustained weight loss we developed a diet-induced obese Roux-en-Y gastric bypass rat model. We review our rat model data from the novel viewpoint of the catabolic state, comparing it with the limited human data available and the catabolic events occurring in cancer anorexia/cachexia syndrome. RECENT FINDINGS Current data suggest the involvement of mechanisms other than restrictive and malabsorptive factors of the Roux-en-Y gastric bypass, classically thought of as the mechanisms responsible for weight loss. Based on available data, gastrointestinal hormones and cytokines play a key role in reducing food intake and regulating energy homeostasis. Because of the cross talk between peripheral modulators and the hypothalamus, a critical role for their interaction in the outcome of Roux-en-Y gastric bypass is emerging. SUMMARY In our Roux-en-Y gastric bypass rat model many of the changes in gastrointestinal hormones, adipokines and cytokines as well as in hypothalamic neuropeptides and neurotransmitters resemble the changes observed in the anorexia/cachexia rat model, suggesting that Roux-en-Y gastric bypass triggers a catabolic state responsible for loss of appetite and prolonged body weight reduction.
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Affiliation(s)
- Ana Guijarro
- Surgical Metabolism and Nutrition Laboratory, Department of Surgery, SUNY Upstate Medical University, Syracuse, New York 13021, USA
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52
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Abstract
Adipose tissue is responsive to both central and peripheral metabolic signals and is itself capable of secreting a number of proteins. These adipocyte-specific or enriched proteins, termed adipokines, have been shown to have a variety of local, peripheral, and central effects. These secreted proteins, which include tumor necrosis factor (TNF)-alpha, resistin, IL-6, IL-8, acylation-stimulating protein (ASP), angiotensinogen, plasminogen activator inhibitor-1 (PAI-1) ("bad" adipokines) and leptin, adiponectin ("good" adipokines) seem to play important regulatory roles in a variety of complex processes, including fat metabolism, feeding behavior, hemostasis, vascular tone, energy balance, and insulin sensitivity, but none is without controversy regarding its respective mechanism and scope of action. The present review is focused on the effects of free fatty acids and a restricted number of adipokines, which have been implicated in vascular (angiotensinogen, PAI-1) and energy and glucose homeostasis (ASP, TNFalpha, IL-6, resistin, leptin, adiponectin).
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Affiliation(s)
- Cristina M Rondinone
- Department Metabolic Diseases, Hoffmann-La Roche, Nutley, New Jersey 07110, USA.
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53
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Abstract
Obesity and obstructive sleep apnea (OSA) often coexist. OSA has been linked to cardiovascular disease. Thus, OSA may contribute to the cardiovascular consequences of obesity. In this review, we explore clinical and pathophysiological interactions between obesity, cardiovascular disease and OSA. We discuss the mechanisms whereby OSA may contribute to hypertension, atherosclerosis, insulin resistance and atrial fibrillation associated with obesity, and emphasize the potential implications for understanding why only a subgroup of obese patients develop cardiovascular disease. Identification of the OSA-dependent and OSA-independent pathways in the cardiovascular pathophysiology of obesity may hold clinical and therapeutic promise.
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Affiliation(s)
- R Wolk
- Department of Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55902, USA
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54
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Raff H, Bruder ED. Adiponectin and resistin in the neonatal rat: effects of dexamethasone and hypoxia. Endocrine 2006; 29:341-4. [PMID: 16785610 PMCID: PMC1481650 DOI: 10.1385/endo:29:2:341] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Revised: 12/16/2005] [Accepted: 12/27/2005] [Indexed: 11/11/2022]
Abstract
Hypoxia is a common neonatal stress that induces insulin resistance and a decrease in body weight gain. Dexamethasone is often used to treat neonatal cardiopulmonary disease, and also leads to insulin resistance and a decrease in body weight gain. The current study addressed the hypothesis that serum concentrations of the adipokines adiponectin and/or resistin are altered during hypoxia and/or dexamethasone therapy in neonatal rats. Rat pups with their lactating dams were exposed to hypoxia (11% O2) from birth and treated with a tapering regimen of dexamethasone from postnatal day (PD) 3-6. Serum adiponectin and resistin were measured on PD7. Hypoxia and dexamethasone independently decreased body weight gain and increased adiponectin levels. The combination of hypoxia and dexamethasone did not further increase adiponectin. Dexamethasone caused a small increase in resistin in normoxic pups, which may facilitate the hyperinsulemic- normoglycemic state we previously described. We also conclude that adiponectin is increased during hypoxia in response to a decrease in the sensitivity to insulin.
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Affiliation(s)
- Hershel Raff
- Endocrine Research Laboratory, St. Luke's Medical Center, Milwaukee, WI 53215, USA.
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55
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Kim SG, Ryu OH, Kim HY, Lee KW, Seo JA, Kim NH, Choi KM, Lee J, Baik SH, Choi DS. Effect of rosiglitazone on plasma adiponectin levels and arterial stiffness in subjects with prediabetes or non-diabetic metabolic syndrome. Eur J Endocrinol 2006; 154:433-40. [PMID: 16498057 DOI: 10.1530/eje.1.02100] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Thiazolidinediones have favorable influences on surrogate markers of atherosclerosis such as adiponectin, and arterial stiffness in diabetic patients. However, it is not well known whether these beneficial effects occur in subjects without diabetes, such as prediabetes or the non-diabetic metabolic syndrome (MetS). The present study was therefore designed to evaluate the effectiveness of the insulin-sensitizing agent rosiglitazone on circulating adipocytokine levels and brachial-ankle pulse wave velocity (baPWV) in non-diabetics. DESIGN AND METHODS Ninety-nine subjects with prediabetes or non-diabetic MetS were randomly assigned to either rosiglitazone or an untreated control group (50 and 49 subjects respectively). The rosiglitazone group was treated daily for 12 weeks with 4 mg rosiglitazone. All subjects received a 75 g oral glucose test (OGTT) before and after treatment. In addition, baPWV, together with the levels of adiponectin, resistin, and high sensitivity C-reactive protein (hsCRP) were determined. RESULTS Rosiglitazone treatment significantly increased circulating adiponectin levels (P < 0.001) relative to the control group (P = 0.21). Plasma resistin levels were unchanged in both the rosiglitazone-treated and -untreated groups, but baPWV and hsCRP were significantly decreased (P < 0.001 and P = 0.003 respectively) in the rosiglitazone group only. Multiple linear regression analysis showed that changes in plasma adiponectin and baPWV were significantly affected by rosiglitazone treatment. CONCLUSIONS These data suggest that rosiglitazone may have an anti-atherogenic effect in subjects with prediabetes or non-diabetic MetS.
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Affiliation(s)
- Sin Gon Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Anam Hospital, Korea University Medical Center, Seoul
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56
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Rondinone CM. Adipocyte-derived hormones, cytokines, and mediators. Endocrine 2006; 29:81-90. [PMID: 16622295 DOI: 10.1385/endo:29:1:81] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 11/30/1999] [Accepted: 10/25/2005] [Indexed: 02/08/2023]
Abstract
Adipose tissue is responsive to both central and peripheral metabolic signals and is itself capable of secreting a number of proteins. These adipocyte-specific or enriched proteins, termed adipokines, have been shown to have a variety of local, peripheral, and central effects. These secreted proteins, which include tumor necrosis factor (TNF)-alpha, resistin, IL-6, IL-8, acylation-stimulating protein (ASP), angiotensinogen, plasminogen activator inhibitor-1 (PAI-1) ("bad" adipokines) and leptin, adiponectin ("good" adipokines) seem to play important regulatory roles in a variety of complex processes, including fat metabolism, feeding behavior, hemostasis, vascular tone, energy balance, and insulin sensitivity, but none is without controversy regarding its respective mechanism and scope of action. The present review is focused on the effects of free fatty acids and a restricted number of adipokines, which have been implicated in vascular (angiotensinogen, PAI-1) and energy and glucose homeostasis (ASP, TNFalpha, IL-6, resistin, leptin, adiponectin).
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Affiliation(s)
- Cristina M Rondinone
- Department Metabolic Diseases, Hoffmann-La Roche, Nutley, New Jersey 07110, USA.
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57
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Liu HS, Chen YH, Hung PF, Kao YH. Inhibitory effect of green tea (-)-epigallocatechin gallate on resistin gene expression in 3T3-L1 adipocytes depends on the ERK pathway. Am J Physiol Endocrinol Metab 2006; 290:E273-81. [PMID: 16159906 DOI: 10.1152/ajpendo.00325.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resistin (Rstn) is known as an adipocyte-specific secretory hormone that can cause insulin resistance and decrease adipocyte differentiation. By contrast, green tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been reported as body weight and diabetes chemopreventatives. Whether EGCG regulates production of Rstn is unknown. Using 3T3-L1 adipocytes, we found that EGCG at 20 and 100 microM suppressed Rstn mRNA levels by approximately 35 and 50%, respectively, after 3 h. The basal half-life of Rstn mRNA induced by actinomycin D was >12 h but shifted to 3 h in the presence of EGCG. This suggests that EGCG regulates the stability of Rstn mRNA. Treatment with cycloheximide did not prevent EGCG-suppressed Rstn mRNA levels, which suggests that the effect of EGCG does not require new protein synthesis. Intracellular Rstn protein significantly decreased in the presence of 100 microM EGCG 3 h after treatment, whereas the release of the Rstn protein did not significantly change. This suggests that EGCG may modulate the distribution of Rstn protein between the intracellular and extracellular compartments. EGCG did not affect the amounts of extracellular signal-related kinase-1/2 (ERK1/2), phospho-JNK, phospho-p38, and phospho-Akt proteins but reduced the amounts of phospho-ERK1/2 proteins. Overexpression with MEK1 blocked EGCG-inhibited Rstn mRNA expression. These data suggest that EGCG downregulates Rstn expression via a pathway that is dependent on the ERK pathway.
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Affiliation(s)
- Hang-Seng Liu
- Department of General Medical Laboratory, Armed Forces Tao-Yuan General Hospital, Chung-Li City, Tao-Yuan, Taiwan
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58
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59
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Regitz-Zagrosek V, Lehmkuhl E, Weickert MO. Gender differences in the metabolic syndrome and their role for cardiovascular disease. Clin Res Cardiol 2006; 95:136-47. [PMID: 16598526 DOI: 10.1007/s00392-006-0351-5] [Citation(s) in RCA: 311] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Accepted: 10/28/2005] [Indexed: 01/12/2023]
Abstract
Women live longer than men and develop cardiovascular disease (CVD) at an older age. The metabolic syndrome represents a major risk factor for the development of CVD, and gender differences in this syndrome may contribute to gender differences in CVD. In recent years, the metabolic syndrome has been more prevalent in men than in women. Prevalence is increasing and this increase has been steeper in women, particularly in young women, during the last decade. The contributions of the different components of the metabolic syndrome differ between genders and in different countries. In a recent survey in Germany, 40% of the adult population had been diagnosed with disturbed glucose tolerance or type 2 diabetes. Undiagnosed diabetes was more frequent in men than in women, and risk factors for undiagnosed diabetes differed between the sexes. Worldwide, in individuals with impaired glucose tolerance, impaired fasting glucose was observed more frequently in men, whereas impaired glucose tolerance occurred relatively more often in women. Lipid accumulation patterns differ between women and men. Premenopausal women more frequently develop peripheral obesity with subcutaneous fat accumulation, whereas men and postmenopausal women are more prone to central or android obesity. In particular, android obesity is associated with increased cardiovascular mortality and the development of type 2 diabetes. Visceral adipocytes differ from peripheral adipocytes in their lipolytic activity and their response to insulin, adrenergic and angiotensin stimulation and sex hormones. Visceral fat is a major source of circulating free fatty acids and cytokines, which are directly delivered via the portal vein to the liver inducing insulin resistance and an atherogenic lipid profile. Inflammation increases cardiovascular risk particularly in women. A relatively greater increase in cardiovascular risk by the appearance of diabetes in women has been reported in many studies.Thus, the presently available data suggest that the pathophysiology of the metabolic syndrome and its contribution to the relative risk of cardiovascular events and heart failure show gender differences, which might be of potential relevance for prevention, diagnostics, and therapy of the syndrome.
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Affiliation(s)
- V Regitz-Zagrosek
- Center for Gender in Medicine and Cardiovascular Disease in Women, Charité and Deutsches Herzzentrum Berlin, Germany.
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60
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Shen YH, Zhang L, Gan Y, Wang X, Wang J, LeMaire SA, Coselli JS, Wang XL. Up-regulation of PTEN (phosphatase and tensin homolog deleted on chromosome ten) mediates p38 MAPK stress signal-induced inhibition of insulin signaling. A cross-talk between stress signaling and insulin signaling in resistin-treated human endothelial cells. J Biol Chem 2006; 281:7727-36. [PMID: 16418168 DOI: 10.1074/jbc.m511105200] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The key feature of metabolic syndrome, a cluster of metabolic and cardiovascular disorders, is systemic insulin resistance, which is associated with dysregulated endothelial nitric-oxide synthase (eNOS). Stress signaling induced by inflammation can inhibit insulin signaling. However, molecular mechanisms for the cross-talk between stress signaling and insulin resistance are only partially understood. Resistin, an adipokine/cytokine, is involved in inflammatory processes that could lead to insulin resistance status and vascular diseases. In the current study, we observed that resistin inhibited insulin signaling and eNOS activation in endothelial cells. Up-regulation of PTEN (phosphatase and tensin homolog deleted on chromosome ten) expression by resistin may mediate the inhibitory effects. Activated stress signaling p38 MAPK, but not JNK, is involved in PTEN up-regulation. We further found that p38 target transcriptional factor activating transcription factor-2 (ATF-2) bound to ATF sites in the PTEN promoter. The phosphorylation/activation of ATF-2 and its binding to PTEN promoter were increased by resistin treatment. In summary, up-regulation of PTEN is involved in the inhibitory effects of resistin on insulin signaling and eNOS activation in endothelial cells. Resistin induces PTEN expression by activating stress signaling p38 pathway, which may activate target transcription factor ATF-2, which in turn induces PTEN expression. Our findings suggest that resistin-mediated inhibition of insulin signaling and eNOS activation may contribute to cardiovascular diseases.
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Affiliation(s)
- Ying H Shen
- Section of Adult Cardiac Surgery, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas 77030, USA.
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61
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Schäffler A, Neumeier M, Herfarth H, Fürst A, Schölmerich J, Büchler C. Genomic structure of human omentin, a new adipocytokine expressed in omental adipose tissue. ACTA ACUST UNITED AC 2005; 1732:96-102. [PMID: 16386808 DOI: 10.1016/j.bbaexp.2005.11.005] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 11/07/2005] [Accepted: 11/12/2005] [Indexed: 11/21/2022]
Abstract
Genomic structure, promoter region, amino acid sequence and exon-specific primer combinations of the human omentin gene are presented. Omentin mRNA expression differs between omental adipose tissue probes from patients with chronic inflammatory bowel diseases such as Crohn's disease. Sequence comparisons revealed a 100% identity of omentin with human intelectin. Based on this, omentin might be a new adipocytokine playing a role in the defense against intestinal bacterial translocation in the context of Crohn's disease.
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Affiliation(s)
- A Schäffler
- Department of Internal Medicine I, University of Regensburg, D-93042 Regensburg, Germany.
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62
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Abstract
Adipose tissue is a highly active organ. In addition to storing calories as triglycerides, it also secretes a large variety of proteins, including cytokines, chemokines and hormone-like factors, such as leptin, adiponectin and resistin. Intriguingly, many, if not most, of these adipose-derived proteins have dual actions; cytokines have both immunomodulatory functions and act as systemic or auto-/paracrine regulators of metabolism, while proteins such as leptin and adiponectin are regulators of both metabolism and inflammation. The production of pro-atherogenic chemokines by adipose tissue is of particular interest since their local secretion, e.g. by perivascular adipose depots, may provide a novel mechanistic link between obesity and the associated vascular complications.
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Affiliation(s)
- Cristiana E Juge-Aubry
- Endocrine Unit, Department of Internal Medicine, University Hospital of Geneva, Switzerland
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63
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Assifi MM, Suchankova G, Constant S, Prentki M, Saha AK, Ruderman NB. AMP-activated protein kinase and coordination of hepatic fatty acid metabolism of starved/carbohydrate-refed rats. Am J Physiol Endocrinol Metab 2005; 289:E794-800. [PMID: 15956049 DOI: 10.1152/ajpendo.00144.2005] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acute increases in the concentration of malonyl-CoA play a pivotal role in mediating the decrease in fatty acid oxidation that occurs in many tissues during refeeding after a fast. In this study, we assess whether such increases in malonyl-CoA in liver could be mediated by malonyl-CoA decarboxylase (MCD), as well as acetyl-CoA carboxylase (ACC). In addition, we examine how changes in the activity of ACC, MCD, and other enzymes that govern fatty acid and glycerolipid synthesis relate temporally to alterations in the activities of the fuel-sensing enzyme AMP-activated protein kinase (AMPK). Rats starved for 48 h and refed a carbohydrate chow diet for 1, 3, 12, and 24 h were studied. Refeeding caused a 40% decrease in the activity of the alpha1-isoform of AMPK within 1 h, with additional decreases in AMPKalpha1 activity and a decrease in AMPKalpha2 occurring between 1 and 24 h. At 1 h, the decrease in AMPK activity was associated with an eightfold increase in the activity of the alpha1-isoform of ACC and a 30% decrease in the activity of MCD, two enzymes thought to be regulated by AMPK. Also, the concentration of malonyl-CoA was increased by 50%. Between 1 and 3 h of refeeding, additional increases in the activity of ACC and decreases in MCD were observed, as was a further twofold increase in malonyl-CoA. Increases in the activity (60%) and abundance (12-fold) of fatty acid synthase occurred predominantly between 3 and 24 h and increases in the activity of mitochondrial sn-glycerol-3-phosphate acyltransferase (GPAT) and acyl-CoA:diaclyglycerol acyltransferase (DGAT) at 12 and 24 h. The results strongly suggest that early changes in the activity of MCD, as well as ACC, contribute to the increase in hepatic malonyl-CoA in the starved-refed rat. They also suggest that the changes in these enzymes, and later occurring increases in enzymes regulating fatty acid and glycerolipid synthesis, could be coordinated by AMPK.
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Affiliation(s)
- Murwarid M Assifi
- Diabetes and Metabolism Unit, Boston Univ. Medical Center, Boston, MA 02118, USA
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64
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Abstract
For many years adipose tissue was viewed as the site where excess energy was stored, in the form of triglycerides (TGs), and where that energy, when needed elsewhere in the body, was released in the form of fatty acids (FAs). Recently, it has become clear that when the regulation of the storage and release of energy by adipose tissue is impaired, plasma FA levels become elevated and excessive metabolism of FA, including storage of TGs, occurs in nonadipose tissues. Most recently, work by several laboratories has made it clear that in addition to FA, adipose tissue communicates with the rest of the body by synthesizing and releasing a host of secreted molecules, collectively designated as adipokines. Several recent reviews have described how these molecules, along with FA, significantly effect total body glucose metabolism and insulin sensitivity. Relatively little attention has been paid to the effects of adipokines on lipid metabolism. In this review, we will describe, in detail, the effects of molecules secreted by adipose tissue, including FA, leptin, adiponectin, resistin, TNF-alpha, IL-6, and apolipoproteins, on lipid homeostasis in several nonadipose tissues, including liver, skeletal muscle, and pancreatic beta cells.
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Affiliation(s)
- Yi-Hao Yu
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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65
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Kougias P, Chai H, Lin PH, Yao Q, Lumsden AB, Chen C. Effects of adipocyte-derived cytokines on endothelial functions: implication of vascular disease. J Surg Res 2005; 126:121-9. [PMID: 15916985 DOI: 10.1016/j.jss.2004.12.023] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Revised: 12/21/2004] [Accepted: 12/26/2004] [Indexed: 11/15/2022]
Abstract
Adipose tissue has recently emerged as an active endocrine organ that secretes a variety of metabolically important substances, collectively called adipocytokines or adipokines. In this review we summarize the effects of the adipokines leptin, adiponectin, and resistin on the vasculature and their potential role for pathogenesis of vascular disease. Leptin is associated with arterial wall thickness, decreased vessel distensibility, and elevated C reactive protein (CRP) levels. Leptin possesses procoagulant and antifibrinolytic properties, and it promotes thrombus and atheroma formation, probably through the leptin receptors by promoting vascular inflammation, proliferation, and calcification, and by increasing oxidative stress. Research for development of pharmacologic antagonism for the leptin receptor is currently under way. Adiponectin inhibits the expression of the adhesion molecules ICAM-1, VCAM-1, and P selectin. Therefore, it interferes with monocyte adherence to endothelial cells and their subsequent migration to the subendothelial space, one of the initial events in the development of atherosclerosis. Adiponectin also inhibits the transformation of macrophages to foam cells in vitro and decreases their phagocytic activity. Resistin, discovered in 2001, represents the newest of the adipokines and was named for its ability to promote insulin resistance. Resistin increases the expression of the adhesion molecules VCAM-1 and ICAM-1, up-regulates the monocyte chemoattractant chemokine-1, and promotes endothelial cell activation via ET-1 release. Although many aspects of its function need further clarification, it appears that resistin will add significantly to our knowledge of the pathophysiology of vascular disease and the metabolic syndrome.
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Affiliation(s)
- Panagiotis Kougias
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030, USA
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66
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67
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Hammarstedt A, Andersson CX, Rotter Sopasakis V, Smith U. The effect of PPARgamma ligands on the adipose tissue in insulin resistance. Prostaglandins Leukot Essent Fatty Acids 2005; 73:65-75. [PMID: 15936183 DOI: 10.1016/j.plefa.2005.04.008] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Insulin resistance is frequently accompanied by obesity and both obesity and type 2 diabetes are associated with a mild chronic inflammation. Elevated levels of various cytokines, such as TNF-alpha and IL-6, are typically found in the adipose tissue in these conditions. It has been suggested that many cytokines produced in the adipose tissue are derived from infiltrated inflammatory cells. However, the adipose tissue itself has proven to be an important endocrine organ, secreting several hormones and cytokines, usually referred to as adipokines. Peroxisome proliferator-activated receptor (PPAR)gamma is essential for adipocyte proliferation and differentiation. In recent years, PPARgamma and its ligands, the thiazolidinediones (TZD), have achieved great attention due to their insulin sensitizing and anti-inflammatory properties. Treatment with TZDs result in improved insulin signaling and adipocyte differentiation, increased adipose tissue influx of free fatty acids and inhibition of cytokine expression and action. As a result, PPARgamma plays a central role in maintaining a functional and differentiated adipose tissue.
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Affiliation(s)
- A Hammarstedt
- The Lundberg Laboratory for Diabetes Research, Department of Internal Medicine, Sahlgrenska University Hospital, SE-413 45, Göteborg, Sweden
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68
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Graveleau C, Zaha VG, Mohajer A, Banerjee RR, Dudley-Rucker N, Steppan CM, Rajala MW, Scherer PE, Ahima RS, Lazar MA, Abel ED. Mouse and human resistins impair glucose transport in primary mouse cardiomyocytes, and oligomerization is required for this biological action. J Biol Chem 2005; 280:31679-85. [PMID: 15983036 DOI: 10.1074/jbc.m504008200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The adipocytokine resistin impairs glucose tolerance and insulin sensitivity in rodents. Here, we examined the effect of resistin on glucose uptake in isolated adult mouse cardiomyocytes. Murine resistin reduced insulin-stimulated glucose uptake, establishing the heart as a resistin target tissue. Notably, human resistin also impaired insulin action in mouse cardiomyocytes, providing the first evidence that human and mouse resistin homologs have similar functions. Resistin is a cysteine-rich molecule that circulates as a multimer of a dimeric form dependent upon a single intermolecular disulfide bond, which, in the mouse, involves Cys26; mutation of this residue to alanine (C26A) produces a monomeric molecule that appears to be bioactive in the liver. Remarkably, unlike native resistin, monomeric C26A resistin had no effect on basal or insulin-stimulated glucose uptake in mouse cardiomyocytes. Resistin impairs glucose uptake in cardiomyocytes by mechanisms that involve altered vesicle trafficking. Thus, in cardiomyocytes, both mouse and human resistins directly impair glucose transport; and in contrast to effects on the liver, these actions of resistin require oligomerization.
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Affiliation(s)
- Christophe Graveleau
- Division of Endocrinology, Metabolism, and Diabetes, University of Utah, Salt Lake City, Utah 84112, USA
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69
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Bokarewa M, Nagaev I, Dahlberg L, Smith U, Tarkowski A. Resistin, an adipokine with potent proinflammatory properties. THE JOURNAL OF IMMUNOLOGY 2005; 174:5789-95. [PMID: 15843582 DOI: 10.4049/jimmunol.174.9.5789] [Citation(s) in RCA: 699] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The adipokine resistin is suggested to be an important link between obesity and insulin resistance. In the present study, we assessed the impact of resistin as inflammatogenic cytokine in the setting of arthritis. In vitro experiments on human PBMC were performed to assess cytokine response and transcription pathways of resistin-induced inflammation. Proinflammatory properties of resistin were evaluated in animal model by intra-articular injection of resistin followed by histological evaluation of the joint. Levels of resistin were assessed by ELISA in 74 paired blood and synovial fluid samples of patients with rheumatoid arthritis. Results were compared with the control group comprised blood samples from 34 healthy individuals and 21 synovial fluids from patients with noninflammatory joint diseases. We now show that resistin displays potent proinflammatory properties by 1) strongly up-regulating IL-6 and TNF-alpha, 2) responding to TNF-alpha challenge, 3) enhancing its own activity by a positive feedback, and finally 4) inducing arthritis when injected into healthy mouse joints. Proinflammatory properties of resistin were abrogated by NF-kappaB inhibitor indicating the importance of NF-kappaB signaling pathway for resistin-induced inflammation. Resistin is also shown to specifically accumulate in the inflamed joints of patients with rheumatoid arthritis and its levels correlate with other markers of inflammation. Our results indicate that resistin is a new and important member of the cytokine family with potent regulatory functions. Importantly, the identified properties of resistin make it a novel and interesting therapeutic target in chronic inflammatory diseases such as rheumatoid arthritis.
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MESH Headings
- Adipocytes/immunology
- Adipocytes/metabolism
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Animals
- Arthritis, Experimental/immunology
- Arthritis, Experimental/metabolism
- Arthritis, Experimental/pathology
- Arthritis, Rheumatoid/immunology
- Arthritis, Rheumatoid/metabolism
- Arthritis, Rheumatoid/pathology
- Cells, Cultured
- Female
- Hormones, Ectopic/administration & dosage
- Hormones, Ectopic/physiology
- Humans
- Inflammation Mediators/administration & dosage
- Inflammation Mediators/physiology
- Injections, Intra-Articular
- Interleukin-1/biosynthesis
- Interleukin-1/genetics
- Interleukin-6/biosynthesis
- Interleukin-6/genetics
- Intracellular Fluid/immunology
- Intracellular Fluid/metabolism
- Male
- Mice
- Middle Aged
- NF-kappa B/metabolism
- NF-kappa B/physiology
- Recombinant Proteins/administration & dosage
- Recombinant Proteins/pharmacology
- Resistin
- Signal Transduction/immunology
- Synovial Membrane/immunology
- Synovial Membrane/metabolism
- Synovial Membrane/pathology
- Tumor Necrosis Factor-alpha/biosynthesis
- Tumor Necrosis Factor-alpha/genetics
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Affiliation(s)
- Maria Bokarewa
- Department of Rheumatology and Inflammation Research, The Sahlgrenska Academy at Göteborg University, Sweden.
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70
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Abstract
Resistin (Rstn) is known as an adipocyte-specific secretory factor that can cause insulin resistance and decrease adipocyte differentiation. Conversely, based on various studies, insulin-like growth factors (IGFs) can improve insulin resistance and stimulate adipocyte adipogenesis. Whether IGFs exert their effects through the control of Rstn's production or modulation of Rstn's action is unknown. This study was designed to examine the influence and the signaling of IGF-I on Rstn gene expression and protein secretion by 3T3-L1 adipocytes. We found that IGF-I suppressed Rstn mRNA expression and protein release in dose- and time-dependent manners. The IC50 of IGF-I was approximately 1 nM for a range of 6-10 h of treatment. Treatment with cycloheximide, but not with actinomycin D, prevented IGF-I-suppressed Rstn mRNA expression, suggesting that IGF-I destabilizes Rstn mRNA and that IGF-I's effect requires new protein, but not mRNA, synthesis. Pretreatment with IGF-I receptor (IGF-IR) antibody blocked IGF-I-altered IGF-IR activity and Rstn mRNA levels. Neither PD-98059, SB-203580, nor LY-294002 changed the IGF-I-decreased levels of Rstn mRNA, but they inhibited IGF-I-stimulated activities of MEK1, p38 MAPK, and phosphoinositide 3-kinase, respectively. However, SB-203580 antagonized the IGF-I-decreased Rstn protein release. These data demonstrate that IGF-I downregulates Rstn gene expression via IGF-IR-dependent and MEK1-, p38 MAPK-, and phosphoinositide 3-kinase-independent pathways and likely modifies the distribution of Rstn protein between the intracellular and extracellular compartments via a p38 MAPK-dependent pathway. Decreases in Rstn production and secretion induced by IGF-I may be related to the mechanism by which IGF-I modulates body weight and diabetes in animals.
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Affiliation(s)
- Yen-Hang Chen
- Department of Life Science, College of Science, National Central University, Chung-Li City, Taoyuan, Taiwan
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71
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Kougias P, Chai H, Lin PH, Lumsden AB, Yao Q, Chen C. Adipocyte-derived cytokine resistin causes endothelial dysfunction of porcine coronary arteries. J Vasc Surg 2005; 41:691-8. [PMID: 15874935 DOI: 10.1016/j.jvs.2004.12.046] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Resistin, a novel adipocyte-derived cytokine, is involved in the development of insulin resistance and diabetes mellitus. In this study, we determined whether resistin could affect vasomotor function, oxidative stress, and endothelial nitric oxide synthase (eNOS) expression in porcine coronary arteries. METHODS Porcine coronary arteries were treated with resistin or antioxidant seleno-L-methionine (SeMet). Vasomotor function was studied by using a myograph system. Levels of superoxide anion (O 2 - ) were detected by the lucigenin-enhanced chemiluminescence method. The eNOS mRNA and protein levels were determined by real-time polymerase chain reaction and immunohistochemistry, respectively. Culture of isolated porcine coronary artery endothelial cells (PCAECs) was also included. RESULTS Endothelium-dependent relaxation in response to bradykinin was reduced by 15% and 30% for the rings treated with 10 and 40 ng/mL of resistin, respectively, as compared with controls ( P < .05). Endothelium-independent relaxation in response to sodium nitroprusside (SNP) was also reduced by 11% after treatment with 40 ng/mL of resistin ( P < .05). The O 2 - level was increased in the 40 ng/mL resistin-treated vessels by 88% as compared with controls ( P < .05). SeMet reversed these effects. The eNOS mRNA levels in PCAEC cultures treated with resistin (10 and 40 ng/mL) were decreased by 27% and 55%, respectively ( P < .05) and by 39% in the endothelial cells purified from porcine coronary artery rings after treatment with 40 ng/mL of resistin ( P < .05). Immunoreactivity of eNOS in the resistin-treated vessel rings was also substantially reduced. CONCLUSIONS Resistin reduces the endothelium-dependent and endothelium-independent vasorelaxation. This effect is associated with increased superoxide radical production, decreased eNOS expression, and is effectively reversed by the antioxidant SeMet. CLINICAL RELEVANCE Obesity has been considered to be an independent risk factor for coronary artery disease and other vascular lesions. Resistin is a newly discovered adipocyte-derived cytokine, and its plasma levels are increased in obese individuals. However, it is not clear whether resistin could directly contribute to vascular disease formation. This study showed that resistin can cause endothelial dysfunction in porcine coronary arteries through oxidative stress and down-regulation of eNOS. Thus, this study may suggest a new mechanism of obesity-associated vascular disease and that antioxidants may effectively prevent vascular disease in obese individuals.
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Affiliation(s)
- Panagiotis Kougias
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, USA
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72
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Abstract
BACKGROUND There is evidence that malnutrition in early life induces a growth retardation leading, in adult life, to manifest components of the metabolic syndrome. However, the impact on obesity seems less clearly established. OBJECTIVE To review the effects of foetal and postnatal malnutrition on the programming of obesity in the context of the metabolic syndrome, as well as the link between central obesity and cardiovascular diseases. METHODS Included in the review were recent papers exploring the mechanisms linking maternal nutrition with impaired foetal growth and later obesity, cardiovascular disease, hypertension and diabetes in humans and animals. RESULTS The programming of obesity during foetal and early postnatal life depends of the timing of maternal malnutrition as well as the postnatal environment. Obesity arises principally in offspring submitted to malnutrition during early stages of gestation and which presented early catch-up growth. The programming may involve the dysregulation of appetite control or the hormonal environment leading to a context favourable to obesity development (hypersecretion of corticosteroids, hyperinsulinaemia and hyperleptinaemia and anomalies in the IGF axis). Adipose tissue secretes actively several factors implicated in inflammation, blood pressure, coagulation and fibrinolysis. The programmed development of intra-abdominal obesity after early growth restriction may thus favour higher prevalence of hypertension and cardiovascular diseases. CONCLUSIONS Abdominal obesity appears in malnourished offspring and is aggravated by early catch-up growth. Higher rates of intra-abdominal obesity observed after growth restriction may participate to hypertension and create atherothrombotic conditions leading to the development of cardiovascular diseases.
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Affiliation(s)
- C Remacle
- Laboratory of Cell Biology, Institute of Life Science, Université Catholique de Louvain, Louvain-la-Neuve B 1348, Belgium.
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73
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Otieno CJ, Bastiaansen J, Ramos AM, Rothschild MF. Mapping and association studies of diabetes related genes in the pig. Anim Genet 2005; 36:36-42. [PMID: 15670129 DOI: 10.1111/j.1365-2052.2004.01217.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mitogen-activated protein kinase 8 (MAPK8), resistin (RETN), 11 beta hydroxysteroid dehydrogenase isoform 1 (HSD11B1) and protein kinase B Akt2 (AKT2) genes are all genes known to affect insulin signalling and have been implicated in the progression of obesity and type 2 diabetes in humans. In this study, polymorphisms in the porcine diabetes related MAPK8, RETN, HSD11B1 and AKT2 genes were identified, mapped and their associations with phenotypic measurements in swine were analysed. Polymorphisms detected in the MAPK8, RETN and HSD11B1 loci were used to genotype a Berkshire-Yorkshire pig breed reference family. Using linkage analysis, RETN, HSD11B1 and MAPK8 genes were mapped to pig chromosomes 2, 9 and 14, respectively, while the AKT2 gene was physically mapped to pig chromosome 6q21. Results presented here suggest associations between the polymorphisms in the MAPK8, RETN and HSD11B1 genes with several phenotypic measurements, including fat deposition traits in the pig. Because these genes have been implicated in obesity and diabetes in humans, and this study suggests associations with fat related traits, further research on these genes in swine may provide useful information on genetic factors underlying lean pork production.
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Affiliation(s)
- C J Otieno
- Department of Animal Science, Iowa State University, 2255 Kildee Hall, Ames, IA 50011, USA
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74
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Brown R, Wiesner G, Ur E, Wilkinson M. Pituitary resistin gene expression is upregulated in vitro and in vivo by dexamethasone but is unaffected by rosiglitazone. Neuroendocrinology 2005; 81:41-8. [PMID: 15809511 DOI: 10.1159/000084873] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Accepted: 01/13/2005] [Indexed: 12/30/2022]
Abstract
A physiological role for the adipose-derived hormone, resistin, remains unsolved and its putative involvement in insulin resistance is largely controversial. Like leptin and other adipokines, we detected resistin in the rodent hypothalamic-pituitary system. In addition, the pituitary corticotrope cell line, AtT20, is also a source of resistin. These data suggested that resistin could be involved in diverse physiological processes in non-adipose tissue. Initial studies indicated that pituitary resistin gene expression was regulated in a nutritional (fed>fasted), age- (young>old) and gender-specific manner (male>female). In the present work we hypothesized that pituitary resistin expression should be regulated through signalling pathways similar to those reported for adipose tissue. For example, dexamethasone (DEX) potently stimulates production of resistin in murine adipose tissue, whereas thiazolidinediones such as rosiglitazone (ROSI), acting via peroxisome proliferator-activated receptor (PPAR)gamma, reportedly inhibit or stimulate resistin expression. Using quantitative real-time RT-PCR we determined that injection of DEX (10 and 50 microg) yielded 7- and 9-fold increases in pituitary resistin gene expression in prepubertal, but not adult mice. In addition, adrenalectomy attenuated pituitary resistin gene expression, which was restored by DEX (10 microg). In AtT20 cells, exposure to corticosterone (10(-7) and 10(-6)M; 24 h) and DEX (10(-9)-10(-6)M) stimulated resistin mRNA more than 65% (p<0.05) and 115% (p<0.0001), respectively. In contrast, ROSI, injected (5 and 20 mg/kg s.c. for 14 days) or given orally (3 mg/kg/day to 10 mg/kg/day for up to 7 weeks), failed to alter pituitary resistin gene expression in healthy male CD1 mice. Treatment of AtT20 cells with ROSI (10(-5)-10(-10)M; 24 h or 96 h) or the PPARgamma agonist GW 1929 (10(-9) and 10(-5)M; 24 h) had no effect on resistin mRNA. The PPARgamma antagonist GW 9662 (10(-6) and 10(-5)M) was also ineffective. In conclusion, pituitary resistin mRNA levels are robustly stimulated by corticosteroids, particularly at the time of puberty. This is consistent with our previous suggestion that resistin may be involved in maturation of the hypothalamic-pituitary axis. In contrast, pituitary resistin gene expression appears to be PPARgamma-independent and therefore different from the situation in adipose tissue.
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Affiliation(s)
- Russell Brown
- Department of Obstetrics and Gynaecology, Faculty of Medicine, Dalhousie University, Halifax, Canada
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75
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Abstract
Macrophages carry out key functions by defending a host from microbial invaders and by clearing endogenous cellular debris. Molecules that are essential for the recognition, phagocytosis and clearance of pathogens also mediate the uptake and degradation of pathogenic lipoproteins. During atherogenesis, for example, scavenging trapped lipoproteins leads to the formation of foam cells and subsequently the activation of these lipid-laden macrophages. Although they are initially clinically silent, these fatty streaks evolve into complex inflammatory plaques that cause significant morbidity and mortality. Thus, interventions that decrease foam cell formation and reduce the inflammatory response of macrophages could become effective therapies for coronary artery disease. Thiazolidinediones (TZDs) might be developed as anti-atherogenic agents on the basis of their actions as ligands for peroxisome proliferator-activated receptor-gamma (PPARgamma).
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Affiliation(s)
- Lina Zhang
- Department of Medicine/Division of Endocrinology, Stanford University School of Medicine, S025, MC 5103, Stanford, CA 94305-5103, USA
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76
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77
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Conneely KN, Silander K, Scott LJ, Mohlke KL, Lazaridis KN, Valle TT, Tuomilehto J, Bergman RN, Watanabe RM, Buchanan TA, Collins FS, Boehnke M. Variation in the resistin gene is associated with obesity and insulin-related phenotypes in Finnish subjects. Diabetologia 2004; 47:1782-8. [PMID: 15517149 PMCID: PMC1249496 DOI: 10.1007/s00125-004-1537-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Accepted: 07/22/2004] [Indexed: 10/26/2022]
Abstract
AIMS/HYPOTHESIS Resistin is a peptide hormone produced by adipocytes that is present at high levels in sera of obese mice and may be involved in glucose homeostasis through regulation of insulin sensitivity. Several studies in humans have found associations between polymorphisms in the resistin gene and obesity, insulin sensitivity and blood pressure. An association between variation in the resistin gene and type 2 diabetes has been reported in some, but not all studies. The aim of this study was to analyse variants of the resistin gene for association with type 2 diabetes and related traits in a Finnish sample. METHODS In 781 cases with type 2 diabetes, 187 spouse controls and 222 elderly controls of Finnish origin, we genotyped four previously identified non-coding single-nucleotide polymorphisms (SNPs): -420C>G from the promoter region, +156C>T and +298G>A from intron 2, and +1084G>A from the 3' untranslated region. We then tested whether these SNPs were associated with type 2 diabetes and related traits. RESULTS The SNPs were not significantly associated with type 2 diabetes. However, SNPs -420C>G, +156C>T and +298G>A and the common haplotype for these three markers were associated with increased values of weight-related traits and diastolic blood pressure in cases, lower weight in elderly control subjects, and lower insulin sensitivity and greater acute insulin response in spouses. Furthermore, the +1084G allele was associated with lower HDL cholesterol in both cases and controls, higher systolic blood pressure and waist circumference in cases, and greater acute insulin response in spouse controls. CONCLUSIONS/INTERPRETATION Our results add to growing evidence that resistin is associated with variation in weight, fat distribution and insulin resistance.
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Affiliation(s)
- K. N. Conneely
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, USA
| | - K. Silander
- Genome Technology Branch, National Human Genome Research Institute, Bethesda, Maryland, USA
- Department of Molecular Medicine, National Public Health Institute, Helsinki, Finland
| | - L. J. Scott
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, USA
| | - K. L. Mohlke
- Genome Technology Branch, National Human Genome Research Institute, Bethesda, Maryland, USA
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA
| | - K. N. Lazaridis
- Genome Technology Branch, National Human Genome Research Institute, Bethesda, Maryland, USA
| | - T. T. Valle
- Diabetes and Genetic Epidemiology Unit, Department of Epidemiology and Health Promotion, National Public Health Institute, Helsinki, Finland
| | - J. Tuomilehto
- Diabetes and Genetic Epidemiology Unit, Department of Epidemiology and Health Promotion, National Public Health Institute, Helsinki, Finland
- Department of Public Health, University of Helsinki, Helsinki, Finland
| | - R. N. Bergman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - R. M. Watanabe
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - T. A. Buchanan
- Department of Medicine, Division of Endocrinology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - F. S. Collins
- Genome Technology Branch, National Human Genome Research Institute, Bethesda, Maryland, USA
| | - M. Boehnke
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, USA
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78
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Rajala MW, Qi Y, Patel HR, Takahashi N, Banerjee R, Pajvani UB, Sinha MK, Gingerich RL, Scherer PE, Ahima RS. Regulation of resistin expression and circulating levels in obesity, diabetes, and fasting. Diabetes 2004; 53:1671-9. [PMID: 15220189 DOI: 10.2337/diabetes.53.7.1671] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Resistin was originally reported as an adipose tissue-specific hormone that provided a link between obesity and diabetes. Resistin protein level was elevated in obese mice and decreased by insulin-sensitizing thiazolidinediones. Immunoneutralization of resistin improved insulin sensitivity in diet-induced obese mice, while the administration of exogenous resistin induced insulin resistance. More recently, we have shown that ablation of the resistin gene in mice decreased fasting glucose through impairment of gluconeogenesis, while resistin treatment in these knockout mice increased hepatic glucose production. However, the link between resistin and glucose homeostasis has been questioned by studies demonstrating reduced, rather than increased, resistin mRNA expression in obese and diabetic mice. To better understand the regulation of resistin, we developed a sensitive and specific RIA resistin that could accurately measure serum resistin levels in several mouse models. We show that while resistin mRNA is indeed suppressed in obese mice, the circulating resistin level is significantly elevated and positively correlated with insulin, glucose, and lipids. Both resistin mRNA expression and protein levels in Lep(ob/ob) mice are suppressed by leptin treatment in parallel with reductions in glucose and insulin. In wild-type mice, serum resistin increases after nocturnal feeding, concordant with rising levels of insulin. Resistin mRNA and protein levels decline in parallel with glucose and insulin during fasting and are restored after refeeding. We performed clamp studies to determine whether resistin is causally related to insulin and glucose. Adipose resistin expression and serum resistin increased in response to hyperinsulinemia and further in response to hyperglycemia. Taken together, these findings suggest that the nutritional regulation of resistin and changes in resistin gene expression and circulating levels in obesity are mediated, at least in part, through insulin and glucose.
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Affiliation(s)
- Michael W Rajala
- Department of Cell Biology and Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
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79
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Schinke T, Haberland M, Jamshidi A, Nollau P, Rueger JM, Amling M. Cloning and functional characterization of resistin-like molecule gamma. Biochem Biophys Res Commun 2004; 314:356-62. [PMID: 14733912 DOI: 10.1016/j.bbrc.2003.12.100] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Resistin, a recently discovered hormone that may play a crucial role in obesity-associated diabetes, is the founding member of a novel family of cysteine-rich proteins that are secreted by specific cell types. Three other members of this family have been described to date and were termed resistin-like molecules (RELMs). Here we describe the cloning and functional characterization of RELMgamma. The mouse RELMgamma-cDNA encodes a protein of 117 amino acids that contains a signal peptide leading to secretion of the protein. By Northern blotting the RELMgamma-mRNA is detectable in bone marrow, spleen, and lung as well as in peripheral blood granulocytes. Promyelocytic HL60 cells transfected with a RELMgamma expression plasmid have an increased proliferation rate compared to mock-transfected cells and display an altered response to retinoic acid-induced granulocytic differentiation. Taken together, these data provide the first experimental evidence that RELMgamma is a secreted molecule with a restricted expression pattern that may play a role in promyelocytic differentiation.
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Affiliation(s)
- Thorsten Schinke
- Department of Trauma and Reconstructive Surgery, Hamburg University, 20246 Hamburg, Germany
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80
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81
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Yang RZ, Huang Q, Xu A, McLenithan JC, Eisen JA, Shuldiner AR, Alkan S, Gong DW, Eison JA. Comparative studies of resistin expression and phylogenomics in human and mouse. Biochem Biophys Res Commun 2003; 310:927-35. [PMID: 14550293 DOI: 10.1016/j.bbrc.2003.09.093] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Resistin is a newly identified adipocytokine that has been proposed to be a link between obesity and type 2 diabetes based on animal studies. However, the role of resistin in the pathogenesis of insulin resistance associated with obesity in humans remains unclear. We comparatively and quantitatively studied the tissue distributions of resistin mRNA between human and mouse. The expression level of resistin mRNA in human adipose tissue is extremely low but detectable by real-time PCR and is about 1/250 of that in the mouse. Remarkably, resistin mRNA is abundant in human primary acute leukemia cells and myeloid cell lines U937 and HL60, but not in the Raw264 mouse myeloid cell line. Resistin expression in U937 cells was not affected by lipopolysaccharide (LPS) or by ciglitazone, a PPARgamma ligand. Phylogenomics revealed that the human resistin gene is the ortholog of its murine counterpart and is located in a region of chromosome 19p13.3, which is syntenic to mouse chromosome 8A1. In addition to the resistin-like molecule (RELM) sequences already reported, bioinformatics analysis disclosed another RELM sequence in the vicinity of RELMbeta on human chromosome 3q13.1, but this sequence is unlikely to encode an expressed gene. Therefore, only two RELMs, resistin and RELMbeta, exist in humans, instead of the three RELMs, resistin, RELMalpha, and RELMbeta, that exist in mice. This finding provides a possible answer to the question of why only two RELMs have been cloned in humans and suggests that the RELM family is not well conserved in evolution and may function differently between species. Therefore, caution should be exercised in interpreting resistin as a link between obesity and insulin resistance in humans. The high expression of resistin in human leukemia cells suggests a hitherto unidentified biological function of resistin in leukocytes.
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Affiliation(s)
- Rong-Ze Yang
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
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82
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Liu YM, Lacorte JM, Viguerie N, Poitou C, Pelloux V, Guy-Grand B, Coussieu C, Langin D, Basdevant A, Clément K. Adiponectin gene expression in subcutaneous adipose tissue of obese women in response to short-term very low calorie diet and refeeding. J Clin Endocrinol Metab 2003; 88:5881-6. [PMID: 14671185 DOI: 10.1210/jc.2003-030886] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adiponectin is an adipocyte-derived protein suggested to be involved in energy homeostasis and in lipid and glucose metabolism. Little is known regarding the consequence of acute changes in energy balance on adiponectin mRNA expression in human adipose tissue. Using a real-time RT-PCR assay, we investigated the effects of 2-d very low calorie diet (VLCD) and subsequent refeeding on adiponectin mRNA expression in sc adipose tissue of morbidly obese women. Basal adiponectin mRNA abundance of the obese women showed a wide distribution (2.6-14.3 mRNA/18S rRNA; coefficient of variation, 51.2%) and was significantly lower than that of lean controls (P < 0.001). In the obese group, the VLCD caused a 33% rise (P < 0.01) in the average level of mRNA, whereas refeeding caused a 32.8% fall (P < 0.05). In contrast, the change in leptin mRNA expression with either VLCD or refeeding was not statistically significant. The obese subjects who showed an acute adiponectin mRNA response to the changes in energy intake had a higher basal level of adiponectin mRNA (P = 0.02) and a borderline-significantly lower body mass index compared with the subjects who showed no or weak adiponectin mRNA response. Insulin sensitivity of the responder subgroup significantly increased by 89% (P = 0.008) after the VLCD, whereas insulin sensitivity of the nonresponder subgroup only increased by 24% (P = 1.56). This study indicates that adiponectin mRNA in sc adipose tissue can acutely respond to short-term energy changes in some obese subjects. Both the levels of adiposity and insulin sensitivity may contribute to the variation in adiponectin gene expression in response to acute energy changes.
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Affiliation(s)
- Yong-Ming Liu
- EA 3502 and Institut National de la Santé et de la Recherche Médicale (INSERM) Avenir and Paris VI University, Department of Nutrition, Hôtel-Dieu, 75004 Paris, France
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83
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Affiliation(s)
- K Motojima
- Department of Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan.
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84
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Minn AH, Patterson NB, Pack S, Hoffmann SC, Gavrilova O, Vinson C, Harlan DM, Shalev A. Resistin is expressed in pancreatic islets. Biochem Biophys Res Commun 2003; 310:641-5. [PMID: 14521959 DOI: 10.1016/j.bbrc.2003.09.061] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Resistin, a recently described adipocyte factor, is regulated by peroxisome proliferator-activated receptor gamma (PPARgamma) agonists. While resistin has been proposed to mediate insulin resistance in rodents, little is known about human resistin and its expression in pancreatic islets has not been tested. The goal of the present study was therefore to analyze whether resistin, like PPARgamma, is expressed in islets. Human islets from seven donors were analyzed by quantitative RT-PCR revealing resistin expression in all samples. Immunohistochemistry using a resistin-specific antibody on human pancreatic sections localized resistin protein to the islets. Mouse resistin was also detected in the Min6 beta cell line. Interestingly, we found a 4-fold increase in islet resistin expression in insulin resistant A-ZIP transgenic compared to wild-type mice. Our results demonstrate that resistin is expressed in islets and up-regulated in insulin resistance and thereby shed new light on the role of resistin in mice and humans.
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Affiliation(s)
- Alexandra H Minn
- Endocrinology Section, Department of Medicine, University of Wisconsin, Madison, WI 53792, USA
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85
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Pravenec M, Kazdová L, Landa V, Zidek V, Mlejnek P, Jansa P, Wang J, Qi N, Kurtz TW. Transgenic and recombinant resistin impair skeletal muscle glucose metabolism in the spontaneously hypertensive rat. J Biol Chem 2003; 278:45209-15. [PMID: 12944409 DOI: 10.1074/jbc.m304869200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Increased serum levels of resistin, a molecule secreted by fat cells, have been proposed as a possible mechanistic link between obesity and insulin resistance. To further investigate the effects of resistin on glucose metabolism, we derived a novel transgenic strain of spontaneously hypertensive rats expressing the mouse resistin gene under the control of the fat-specific aP2 promoter and also performed in vitro studies of the effects of recombinant resistin on glucose metabolism in isolated skeletal muscle. Expression of the resistin transgene was detected by Northern blot analysis in adipose tissue and by real-time PCR in skeletal muscle and was associated with increased serum fatty acids and muscle triglycerides, impaired skeletal muscle glucose metabolism, and glucose intolerance in the absence of any changes in serum resistin concentrations. In skeletal muscle isolated from non-transgenic spontaneously hypertensive rats, in vitro incubation with recombinant resistin significantly inhibited insulin-stimulated glycogenesis and reduced glucose oxidation. These findings raise the possibility that autocrine effects of resistin in adipocytes, leading to release of other prodiabetic effector molecules from fat and/or paracrine actions of resistin secreted by adipocytes embedded within skeletal muscle, may contribute to the pathogenesis of disordered skeletal muscle glucose metabolism and impaired glucose tolerance.
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MESH Headings
- Adipocytes/metabolism
- Animals
- Animals, Genetically Modified
- Blotting, Northern
- Blotting, Western
- Body Weight
- Glucose/metabolism
- Glucose Tolerance Test
- Glycogen/metabolism
- Hormones, Ectopic/blood
- Hormones, Ectopic/genetics
- Hormones, Ectopic/metabolism
- Intercellular Signaling Peptides and Proteins
- Lipid Metabolism
- Mice
- Mice, Inbred BALB C
- Models, Biological
- Muscle, Skeletal/metabolism
- Nerve Growth Factor
- Oxygen/metabolism
- Phenotype
- Promoter Regions, Genetic
- Proteins
- Rats
- Rats, Inbred SHR
- Recombinant Proteins/metabolism
- Resistin
- Reverse Transcriptase Polymerase Chain Reaction
- Time Factors
- Transgenes
- Triglycerides/metabolism
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Affiliation(s)
- Michal Pravenec
- Institute of Physiology, Czech Academy of Sciences and the Center for Integrated Genomics, Prague 14220, Czech Republic.
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Aruna B, Ghosh S, Singh AK, Mande SC, Srinivas V, Chauhan R, Ehtesham NZ. Human recombinant resistin protein displays a tendency to aggregate by forming intermolecular disulfide linkages. Biochemistry 2003; 42:10554-9. [PMID: 12962478 DOI: 10.1021/bi034782v] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Resistin, a small cysteine rich protein secreted by adipocytes, has been proposed to be a link between obesity and type II diabetes by modulating the insulin signaling pathway and thus inducing insulin resistance. Resistin protein, with 11 cysteine residues, was not significantly homologous at the amino acid level to any other known cysteine rich proteins. Resistin cDNA derived from human subcutaneous adipose tissue was expressed in Escherichia coli as an N-terminal six-His-tag fusion protein. The overexpressed recombinant resistin was purified to homogeneity from inclusion bodies, after solubilization in 8 M urea, using a metal affinity column. While MALDI-TOF mass spectrometric analysis of the purified protein generated a single peak corresponding to the estimated size of 11.3 kDa, the protein exhibited a concentration-dependent oligomerization which is evident from size exclusion chromatography. The oligomeric structure was SDS-insensitive but beta-mercaptoethanol-sensitive, pointing to the importance of disulfide linkages in resistin oligomerization. Estimation of free cysteine residues using the NBD-Cl assay revealed a concentration- and time-dependent increase in the extent of formation of disulfide linkages. The presence of intermolecular disulfide bond(s), crucial in maintaining the global conformation of resistin, was further evident from fluorescence emission spectra. Circular dichroism spectra revealed that recombinant resistin has a tendency to reversibly convert from alpha-helical to beta-sheet structure as a direct function of protein concentration. Our novel observations on the biophysical and biochemical features of human resistin, particularly those shared with prion proteins, may have a bearing on its likely physiological function.
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Affiliation(s)
- Battu Aruna
- Molecular Biology Unit, National Institute of Nutrition, Indian Council of Medical Research, Jamai-Osmania PO, Hyderabad 500007, India
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Rudolph MC, McManaman JL, Hunter L, Phang T, Neville MC. Functional development of the mammary gland: use of expression profiling and trajectory clustering to reveal changes in gene expression during pregnancy, lactation, and involution. J Mammary Gland Biol Neoplasia 2003; 8:287-307. [PMID: 14973374 DOI: 10.1023/b:jomg.0000010030.73983.57] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To characterize the molecular mechanisms by which progesterone withdrawal initiates milk secretion, we examined global gene expression during pregnancy and lactation in mice, focusing on the period around parturition. Trajectory clustering was used to profile the expression of 1358 genes that changed significantly between pregnancy day 12 and lactation day 9. Predominantly downward trajectories included stromal and proteasomal genes and genes for the enzymes of fatty acid degradation. Milk protein gene expression increased throughout pregnancy, whereas the expression of genes for lipid synthesis increased sharply at the onset of lactation. Examination of regulatory genes with profiles similar or complementary to those of lipid synthesis genes led to a model in which progesterone stimulates synthesis of TGF-beta, Wnt 5b, and IGFBP-5 during pregnancy. These factors are suggested to repress secretion by interfering with PRL and IGF-1 signaling. With progesterone withdrawal, PRL and IGF-1 signaling are activated, in turn activating Akt/PKB and the SREBPs, leading to increased lipid synthesis.
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Affiliation(s)
- Michael C Rudolph
- Department of Physiology and Biophysics, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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