151
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Su L, Wang SH, Han RL, Sun GR, Bai YC, Lv SJ, Kang XT. Polymorphisms of the PNPLA3 gene and their associations with chicken growth and carcass traits. Br Poult Sci 2012; 53:453-9. [PMID: 23130579 DOI: 10.1080/00071668.2012.713465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
1. An F(2) resource population of Gushi chickens crossed with Anka broilers was used to investigate the genetic effects of the chicken PNPLA3 gene on growth and adipose accumulation. 2. Associations between three SNPs (g.40006G > T, g.42344T > C and g.42404A > T) and broiler traits were determined using linkage disequilibrium, haplotype construction and association analysis. 3. The g.40006G > T mutation was associated with body weights at 4, 6, 8, 10 and 12 weeks of age, carcass weight, evisceration weight and semi-evisceration weight (P < 0.05). 4. Haplotypes of the g.42344T > C and g.42404A > T mutations were associated with body weight at 12 weeks, carcass weight, evisceration weight, and semi-evisceration weight (P < 0·05) and were associated with significant dominance effects. 5. The results suggest that the PNPLA3 gene may be in linkage with the causative mutation or a QTL controlling growth traits in chickens. In contrast to human studies, the polymorphisms were not associated with fat related traits.
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Affiliation(s)
- L Su
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, 450002 Zhengzhou, P R China
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152
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Xin YN, Zhao Y, Lin ZH, Jiang X, Xuan SY, Huang J. Molecular dynamics simulation of PNPLA3 I148M polymorphism reveals reduced substrate access to the catalytic cavity. Proteins 2012; 81:406-14. [PMID: 23042597 DOI: 10.1002/prot.24199] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 09/20/2012] [Accepted: 09/20/2012] [Indexed: 12/13/2022]
Abstract
A missense mutation I148M in PNPLA3 (patatin-like phospholipase domain-containing 3 protein) is significantly correlated with nonalcoholic fatty liver disease (NAFLD). To glean insights into mutation's effect on enzymatic activity, we performed molecular dynamics simulation and flexible docking studies. Our data show that the size of the substrate-access entry site is significantly reduced in mutants, which limits the access of palmitic acid to the catalytic dyad. Besides, the binding free energy calculations suggest low affinity for substrate to mutant enzyme. The substrate-bound system simulations reveal that the spatial arrangement of palmitic acid is distinct in wild-type from that in mutant. The substrate recognition specificity is lost due to the loop where the I148M mutation was located. Our results provide strong evidence for the mechanism by which I148M affects the enzyme activity and suggest that mediating the dynamics may offer a potential avenue for NAFLD.
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Affiliation(s)
- Yong-Ning Xin
- College of Medicine and Pharmaceutics, Ocean University of China, Qingdao 266003, Shandong Province, China
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153
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Yilmaz Y. Review article: is non-alcoholic fatty liver disease a spectrum, or are steatosis and non-alcoholic steatohepatitis distinct conditions? Aliment Pharmacol Ther 2012; 36:815-23. [PMID: 22966992 DOI: 10.1111/apt.12046] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 08/17/2012] [Accepted: 08/22/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is currently conceptualised as a clinical spectrum that results from a ‘multiple-hit’ process which begins with simple steatosis and subsequently renders the hepatocytes susceptible to a variety of insults. Ultimately, more serious liver injuries like non-alcoholic steatohepatitis (NASH) and cirrhosis may develop. Although the metabolic syndrome is considered the crucial player in the pathogenesis of NAFLD, recent studies have highlighted novel pathophysiological mechanisms in this clinical entity. AIM To discuss the pathophysiology of NAFLD based on the hypothesis that simple steatosis and NASH are discrete entities rather than two points on a spectrum. METHODS A literature search was conducted in August 2012 on PubMed, Ovid Embase, Ovid Medline and Scopus using the following search terms: steatosis, non-alcoholic steatohepatitis, pathophysiology, fatty liver, natural history and genetics. RESULTS Simple steatosis and NASH appear as two distinct pathophysiological entities and progression from pure fatty liver to NASH appears to be so rare as to warrant publication. The possible pathogenetic pathways specifically related to NASH are highlighted. CONCLUSIONS Although simple steatosis and non-alcoholic steatohepatitis are currently viewed as two histological subtypes of the unique spectrum of non-alcoholic fatty liver disease, the two conditions are likely distinct not only from a histological but also from a pathophysiological standpoint. Efforts to distinguish simple steatosis from non-alcoholic steatohepatitis using non-invasive modalities should be informed by the current pathophysiology of these two clinical entities.
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Affiliation(s)
- Y Yilmaz
- Institute of Gastroenterology, Marmara University, Maltepe, Istanbul, Turkey.
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154
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Sevastianova K, Santos A, Kotronen A, Hakkarainen A, Makkonen J, Silander K, Peltonen M, Romeo S, Lundbom J, Lundbom N, Olkkonen VM, Gylling H, Fielding BA, Rissanen A, Yki-Järvinen H. Effect of short-term carbohydrate overfeeding and long-term weight loss on liver fat in overweight humans. Am J Clin Nutr 2012; 96:727-34. [PMID: 22952180 DOI: 10.3945/ajcn.112.038695] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Cross-sectional studies have identified a high intake of simple sugars as an important dietary factor predicting nonalcoholic fatty liver disease (NAFLD). OBJECTIVE We examined whether overfeeding overweight subjects with simple sugars increases liver fat and de novo lipogenesis (DNL) and whether this is reversible by weight loss. DESIGN Sixteen subjects [BMI (kg/m²): 30.6 ± 1.2] were placed on a hypercaloric diet (>1000 kcal simple carbohydrates/d) for 3 wk and, thereafter, on a hypocaloric diet for 6 mo. The subjects were genotyped for rs739409 in the PNPLA3 gene. Before and after overfeeding and after hypocaloric diet, metabolic variables and liver fat (measured by proton magnetic resonance spectroscopy) were measured. The ratio of palmitate (16:0) to linoleate (18:2n-6) in serum and VLDL triglycerides was used as an index of DNL. RESULTS Carbohydrate overfeeding increased weight (±SEM) by 2% (1.8 ± 0.3 kg; P < 0.0001) and liver fat by 27% from 9.2 ± 1.9% to 11.7 ± 1.9% (P = 0.005). DNL increased in proportion to the increase in liver fat and serum triglycerides in subjects with PNPLA3-148IIbut not PNPLA3-148MM. During the hypocaloric diet, the subjects lost 4% of their weight (3.2 ± 0.6 kg; P < 0.0001) and 25% of their liver fat content (from 11.7 ± 1.9% to 8.8 ± 1.8%; P < 0.05). CONCLUSIONS Carbohydrate overfeeding for 3 wk induced a >10-fold greater relative change in liver fat (27%) than in body weight (2%). The increase in liver fat was proportional to that in DNL. Weight loss restores liver fat to normal. These data indicate that the human fatty liver avidly accumulates fat during carbohydrate overfeeding and support a role for DNL in the pathogenesis of NAFLD. This trial was registered at www.hus.fi as 235780.
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155
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Rembeck K, Maglio C, Lagging M, Christensen PB, Färkkilä M, Langeland N, Buhl MR, Pedersen C, Mørch K, Norkrans G, Hellstrand K, Lindh M, Pirazzi C, Burza MA, Romeo S, Westin J. PNPLA 3 I148M genetic variant associates with insulin resistance and baseline viral load in HCV genotype 2 but not in genotype 3 infection. BMC MEDICAL GENETICS 2012; 13:82. [PMID: 22978414 PMCID: PMC3495049 DOI: 10.1186/1471-2350-13-82] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 06/20/2012] [Indexed: 12/16/2022]
Abstract
Background Hepatic steatosis in HCV patients has been postulated as a risk factor associated with a higher frequency of fibrosis and cirrhosis. A single genetic variant, PNPLA3 I148M, has been widely associated with increased hepatic steatosis. Previous studies of the PNPLA3 I148M sequence variant in HCV infected individuals have reported an association between this variant and prevalence of steatosis, fibrosis, and cirrhosis. To evaluate the impact of PNPLA3 I148M variant on metabolic traits and treatment response in HCV genotype 2 and 3 infected patients. Methods Three hundred and eighty-two treatment naïve HCV genotype 2 or 3 infected patients were included in a phase III, open label, randomized, multicenter, investigator-initiated trial (the NORDynamIC study), in which pretreatment liver biopsies were mandatory. PNPLA3I148M genotyping was performed in a total of 359 Caucasian patients. Results In HCV genotype 2 infected patients carrying the PNPLA3 148M allele, there was significantly increased insulin resistance (P = 0.023) and lower viral load (P = 0.005) at baseline as well as the first seven days of antiviral treatment. These results were not observed in HCV genotype 3 infected patients. Conclusions Our results suggest a possible association between the PNPLA3 148M allele and insulin resistance as well as baseline viral load in HCV genotype 2, but not in genotype 3.
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Affiliation(s)
- Karolina Rembeck
- Department of Infectious Diseases/Virology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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156
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Valenti L, Rametta R, Ruscica M, Dongiovanni P, Steffani L, Motta BM, Canavesi E, Fracanzani AL, Mozzi E, Roviaro G, Magni P, Fargion S. The I148M PNPLA3 polymorphism influences serum adiponectin in patients with fatty liver and healthy controls. BMC Gastroenterol 2012; 12:111. [PMID: 22898488 PMCID: PMC3444917 DOI: 10.1186/1471-230x-12-111] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 08/07/2012] [Indexed: 12/13/2022] Open
Abstract
Background Reduced adiponectin is implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH), and the I148M Patatin-like phospholipase domain-containing 3 (PNPLA3) polymorphism predisposes to NAFLD and liver damage progression in NASH and chronic hepatitis C (CHC) by still undefined mechanisms, possibly involving regulation of adipose tissue function. Aim of this study was to evaluate whether the I148M PNPLA3 polymorphism influences serum adiponectin in liver diseases and healthy controls. Methods To this end, we considered 144 consecutive Italian patients with NAFLD, 261 with CHC, 35 severely obese subjects, and 257 healthy controls with very low probability of steatosis, all with complete clinical and genetic characterization, including adiponectin (ADIPOQ) genotype. PNPLA3 rs738409 (I148M) and ADIPOQ genotypes were evaluated by Taqman assays, serum adiponectin by ELISA. Adiponectin mRNA levels were evaluated by quantitative real-time PCR in the visceral adipose tissue (VAT) of 35 obese subjects undergoing bariatric surgery. Results Adiponectin levels were independently associated with the risk of NAFLD and with the histological severity of the disease. Adiponectin levels decreased with the number of 148 M PNPLA3 alleles at risk of NASH both in patients with NAFLD (p = 0.03), and in healthy subjects (p = 0.04). At multivariate analysis, PNPLA3 148 M alleles were associated with low adiponectin levels (<6 mg/ml, median value) independently of NAFLD diagnosis, age, gender, BMI, and ADIPOQ genotype (OR 1.67, 95% c.i. 1.07-2.1 for each 148 M allele). The p.148 M PNPLA3 variant was associated with decreased adiponectin mRNA levels in the VAT of obese patients (p < 0.05) even in the absence of NASH. In contrast, in CHC, characterized by adiponectin resistance, low adiponectin was associated with male gender and steatosis, but not with PNPLA3 and ADIPOQ genotypes and viral features. Conclusions The I148M PNPLA3 variant is associated with adiponectin levels in patients with NAFLD and in healthy subjects, but in the presence of adiponectin resistance not in CHC patients. The I148M PNPLA3 genotype may represent a genetic determinant of serum adiponectin levels. Modulation of serum adiponectin might be involved in mediating the susceptibility to steatosis, NASH, and hepatocellular carcinoma in carriers of the 148 M PNPLA3 variant without CHC, with potential therapeutic implications.
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Affiliation(s)
- Luca Valenti
- Department of Internal Medicine, Università degli Studi Milano, UO Medicina Interna 1B, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
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157
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Roy N, Mukhopadhyay I, Das K, Pandit P, Majumder PP, Santra A, Datta S, Banerjee S, Chowdhury A. Genetic variants of TNFα, IL10, IL1β, CTLA4 and TGFβ1 modulate the indices of alcohol-induced liver injury in East Indian population. Gene 2012; 509:178-88. [PMID: 22902304 DOI: 10.1016/j.gene.2012.07.077] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/31/2012] [Indexed: 02/06/2023]
Abstract
Alcohol induced liver disease or alcoholic liver disease (ALD), a complex trait, encompasses a gamut of pathophysiological alterations in the liver due to continuous exposure to a toxic amount of alcohol (more than 80 g per day). Of all chronic heavy drinkers, only 15-20% develops hepatitis or cirrhosis concomitantly or in succession. Several studies revealed that inter-individual as well as inter-ethnic genetic variation is one of the major factors that predispose to ALD. The role of genetic factors in ALD has long been sought for in ethnically distinct population groups. ALD is fast emerging as an important cause of chronic liver disease in India; even in populations such as "Bengalis" who were "culturally immune" earlier. While the genetic involvement in the pathogenesis of ALD is being sought for in different races, the complex pathophysiology of ALD as well as the knowledge of population level diversity of the relevant alcohol metabolizing and inflammatory pathways mandates the need for well designed studies of genetic factors in ethnically distinct population groups. An array of cytokines plays a critical role as mediators of injury, inflammation, fibrosis and cirrhosis in ALD. We, therefore, studied the association of polymorphisms in five relevant cytokine genes with "clinically significant" ALD in an ethnic "Bengali" population in Eastern India. Compared with "alcoholic" controls without liver disease (n=110), TNFα -238AA genotype, IL1β -511CC genotype, TGFβ1 -509CC genotype and IL10 -592AA genotype were significantly overrepresented in ALD patients (n=181; OR=2.4 and 95% CI 1.2-5.5, P(genotype)=0.042, P(allelic)=0.008; OR=2.7 and 95% CI 1.2-5.9, P(genotype)=0.018, P(allelic)=0.023; OR=4.7 and 95% CI 1.7-13.1, P(genotype)=0.003, P(allelic)=0.014; and OR=2.2 and 95% CI 1.1-4.8, P(genotype)=0.04, P(allelic)=0.039 respectively). Moreover a cumulative genetic risk analysis revealed a significant trend for developing ALD with an increase in the number of risk alleles on IL10 and TGFβ1 loci among alcoholics. The risk genotype of IL1β and TGFβ1 also influences the total bilirubin, albumin and alanine aminotransferase levels among alcoholic "Bengalis". The present study is the first case-control study from Eastern India that comprehensively identified polymorphic markers in TNFα, IL10, IL1β and TGFβ1 genes to be associated with ALD in the Bengali population, accentuating the significance of genetic factors in clinical expressions of ALD.
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Affiliation(s)
- Neelanjana Roy
- Centre for Liver Research, Institute of Post Graduate Medical Education & Research, Kolkata, India.
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158
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Li Q, Qu HQ, Rentfro AR, Grove ML, Mirza S, Lu Y, Hanis CL, Fallon MB, Boerwinkle E, Fisher-Hoch SP, McCormick JB. PNPLA3 polymorphisms and liver aminotransferase levels in a Mexican American population. ACTA ACUST UNITED AC 2012; 35:E237-45. [PMID: 22863562 DOI: 10.25011/cim.v35i4.17153] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Indexed: 12/13/2022]
Abstract
PURPOSE This study examined genetic associations of patatin-like phospholipase domain containing 3 gene (PNPLA3) polymorphisms and liver aminotransferases in an extensively documented, randomly recruited Mexican American population at high risk of liver disease. METHODS Two single nucleotide polymorphisms (SNP) in the PNPLA3 gene (i.e., rs738409 and rs2281135) were genotyped in 1532 individuals. Population stratification was corrected by the genotyping of 103 ancestry informative markers (AIMs) for Mexican Americans. RESULTS Both PNPLA3 SNPs showed highly significant association with alanine aminotransferase (ALT) levels, but was also, in males, associated with aspartate aminotransferase (AST) levels. Haplotypic association test of the two SNPs suggested stronger genetic association with rs738409 than rs2281135. Obvious sex effects were observed: rs738409-sex interaction in ALT levels P = 8.37 x 10(-4); rs738409-sex interaction in AST levels P = 5.03 x 10(-3). CONCLUSIONS This population study highlights a sex-specific association of PNPLA3 polymorphisms and elevated liver enzymes in a population-based study, independent of common pathological factors of the metabolic syndrome. The strong genetic association found in women ≤ 50 years old, but not in women > 50 years old, suggests that sex hormones may mediate the sex effect.
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Affiliation(s)
- Quan Li
- The University of Texas School of Public Health, Brownsville, TX 78520, USA
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159
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Athinarayanan S, Liu W. Non-Alcoholic Fatty Liver Disease: Current Perspectives and Future Direction in Disease pathogenesis, Treatment and Diagnosis. Med Chem 2012; 2:e104. [PMID: 24660114 PMCID: PMC3959643 DOI: 10.4172/2161-0444.1000e104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in the world. An important implication of this disease is the progression of the disease to a more complicated condition called non-alcoholic steatohepatitis (NASH) and the wide variety of clinical presentations. Over the past 5 years, remarkable progresses have been made in understanding the genetic basis for the disease. Recent clinical trials in pharmacotherapy for the disease have been encouraging as well. It is anticipated that the integration of the wide spectrum information retrieved from genomics, transcriptomics and proteomics studies conducted in NAFLD and NASH will mediate a better understanding of the disease pathogenesis and facilitate the postulation of disease pathobiology pathways. Genetic and biological markers identified from the omics studies may hold promise for diagnosis, personalized treatment, early prevention and new drug development.
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Affiliation(s)
- Shaminie Athinarayanan
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University. West Lafayette, IN 47907, USA
| | - Wanqing Liu
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University. West Lafayette, IN 47907, USA
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160
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Hsu E, Murray K. Is nonalcoholic fatty liver disease in children the same disease as in adults? Clin Liver Dis 2012; 16:587-98. [PMID: 22824482 DOI: 10.1016/j.cld.2012.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children, and can present in toddlerhood. There is a differential distribution of NAFLD in children based on race and gender. The gold standard for diagnosis and classification of pediatric NAFLD is liver biopsy although ongoing studies aim to identify and define noninvasive investigations for pediatric NAFLD. Treatments that have been shown to be successful in adult NAFLD, such as insulin sensitizers and Vitamin E, have not been proven to be as definitively successful in children with NAFLD.
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Affiliation(s)
- Evelyn Hsu
- Division of Pediatric Gastroenterology and Hepatology, Seattle Children's Hospital, WA 98115, USA.
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161
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Krarup NT, Grarup N, Banasik K, Friedrichsen M, Færch K, Sandholt CH, Jørgensen T, Poulsen P, Witte DR, Vaag A, Sørensen T, Pedersen O, Hansen T. The PNPLA3 rs738409 G-allele associates with reduced fasting serum triglyceride and serum cholesterol in Danes with impaired glucose regulation. PLoS One 2012; 7:e40376. [PMID: 22792295 PMCID: PMC3390392 DOI: 10.1371/journal.pone.0040376] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 06/04/2012] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND AIM Non-alcoholic fatty liver disease (NAFLD) is a common condition, associated with hepatic insulin resistance and the metabolic syndrome including hyperglycaemia and dyslipidemia. We aimed at studying the potential impact of the NAFLD-associated PNPLA3 rs738409 G-allele on NAFLD-related metabolic traits in hyperglycaemic individuals. METHODS The rs738409 variant was genotyped in the population-based Inter99 cohort examined by an oral glucose-tolerance test, and a combined study-sample consisting of 192 twins (96 twin pairs) and a sub-set of the Inter99 population (n = 63) examined by a hyperinsulinemic euglycemic clamp (n(total) = 255). In Inter99, we analyzed associations of rs738409 with components of the WHO-defined metabolic syndrome (n = 5,847) and traits related to metabolic disease (n = 5,663). In the combined study sample we elucidated whether the rs738409 G-allele altered hepatic or peripheral insulin sensitivity. Study populations were divided into individuals with normal glucose-tolerance (NGT) and with impaired glucose regulation (IGR). RESULTS The case-control study showed no associations with components of the metabolic syndrome or the metabolic syndrome. Among 1,357 IGR individuals, the rs738409 G-allele associated with decreased fasting serum triglyceride levels (per allele effect(β) = -9.9% [-14.4%;-4.0% (95% CI)], p = 5.1×10(-5)) and fasting total cholesterol (β = -0.2 mmol/l [-0.3;-0.01 mmol/l(95% CI)], p = 1.5×10(-4)). Meta-analyses showed no impact on hepatic or peripheral insulin resistance in carriers of the rs738409 G-allele. CONCLUSION Our findings suggest that the G-allele of PNPLA3 rs738409 associates with reduced fasting levels of cholesterol and triglyceride in individuals with IGR.
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Affiliation(s)
- Nikolaj Thure Krarup
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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162
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Johansson LE, Danielsson APH, Parikh H, Klintenberg M, Norström F, Groop L, Ridderstråle M. Differential gene expression in adipose tissue from obese human subjects during weight loss and weight maintenance. Am J Clin Nutr 2012; 96:196-207. [PMID: 22648723 DOI: 10.3945/ajcn.111.020578] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Differential gene expression in adipose tissue during diet-induced weight loss followed by a weight stability period is poorly characterized. Markers of these processes may provide a deeper understanding of underlying mechanisms. OBJECTIVE We aimed to identify differentially expressed genes in human adipose tissue during weight loss and weight maintenance after weight loss. DESIGN RNA from subcutaneous abdominal adipose tissue from 9 obese subjects was analyzed by using a complementary DNA microarray at baseline after weight loss on a low-calorie diet and after weight maintenance. RESULTS Subjects lost 18.8 ± 1.8% of weight and maintained this loss during weight maintenance (1.1 ± 2.1%; range: -9.3 to 10.6%). Most differentially expressed genes exhibited a reciprocal regulation and returned to baseline after weight loss (2163 genes) and weight maintenance (3175 genes). CETP and ABCG1, both of which participate in the HDL-mediated reverse cholesterol transport (RCT), were among the most upregulated of the 750 genes that were differentially expressed after both processes. Several genes involved in inflammation were downregulated. The use of real-time polymerase chain reaction confirmed or partially confirmed the previously implicated genes TNMD and MMP9 (both downregulated), PNPLA3 (upregulated), and CIDEA and SCD (both reciprocally regulated). CONCLUSIONS The beneficial effects of weight loss should be investigated after long-term weight maintenance. The processes of weight loss and weight maintenance should be viewed as biologically distinct. CETP and ABCG1 may be important mediators of these effects through HDL-mediated RCT.
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Affiliation(s)
- Lovisa E Johansson
- Department of Clinical Sciences Malmö, Clinical Obesity, Lund University Diabetes Centre, Lund University, Malmö, Sweden
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163
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Palmer CNA, Maglio C, Pirazzi C, Burza MA, Adiels M, Burch L, Donnelly LA, Colhoun H, Doney AS, Dillon JF, Pearson ER, McCarthy M, Hattersley AT, Frayling T, Morris AD, Peltonen M, Svensson PA, Jacobson P, Borén J, Sjöström L, Carlsson LMS, Romeo S. Paradoxical lower serum triglyceride levels and higher type 2 diabetes mellitus susceptibility in obese individuals with the PNPLA3 148M variant. PLoS One 2012; 7:e39362. [PMID: 22724004 PMCID: PMC3377675 DOI: 10.1371/journal.pone.0039362] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 05/18/2012] [Indexed: 01/23/2023] Open
Abstract
Background Obesity is highly associated with elevated serum triglycerides, hepatic steatosis and type 2 diabetes (T2D). The I148M (rs738409) genetic variant of patatin-like phospholipase domain-containing 3 gene (PNPLA3) is known to modulate hepatic triglyceride accumulation, leading to steatosis. No association between PNPLA3 I148M genotype and T2D in Europeans has been reported. Aim of this study is to examine the relationship between PNPLA3 I148M genotypes and serum triglycerides, insulin resistance and T2D susceptibility by testing a gene-environment interaction model with severe obesity. Methods and Findings PNPLA3 I148M was genotyped in a large obese cohort, the SOS study (n = 3,473) and in the Go-DARTS (n = 15,448), a T2D case-control study. Metabolic parameters were examined across the PNPLA3 I148M genotypes in participants of the SOS study at baseline and at 2- and 10-year follow up after bariatric surgery or conventional therapy. The associations with metabolic parameters were validated in the Go-DARTS study. Serum triglycerides were found to be lower in the PNPLA3 148M carriers from the SOS study at baseline and from the Go-DARTS T2D cohort. An increased risk for T2D conferred by the 148M allele was found in the SOS study (O.R. 1.09, 95% C.I. 1.01-1.39, P = 0.040) and in severely obese individuals in the Go-DARTS study (O.R. 1.37, 95% C.I. 1.13-1.66, P = 0.001). The 148M allele was no longer associated with insulin resistance or T2D after bariatric surgery in the SOS study and no association with the 148M allele was observed in the less obese (BMI<35) individuals in the Go-DARTS study (P for interaction = 0.002). This provides evidence for the obesity interaction with I48M allele and T2D risk in a large-scale cross-sectional and a prospective interventional study. Conclusions Severely obese individuals carrying the PNPLA3 148M allele have lower serum triglyceride levels, are more insulin resistant and more susceptible to T2D. This study supports the hypothesis that obesity-driven hepatic lipid accumulation may contribute to T2D susceptibility.
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Affiliation(s)
- Colin N. A. Palmer
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Cristina Maglio
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carlo Pirazzi
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Maria Antonella Burza
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Martin Adiels
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lindsay Burch
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Louise A. Donnelly
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Helen Colhoun
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Alexander S. Doney
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - John F. Dillon
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Ewan R. Pearson
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Mark McCarthy
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Andrew T. Hattersley
- Peninsula NIHR Clinical Research Facility, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom
| | - Tim Frayling
- Peninsula NIHR Clinical Research Facility, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, United Kingdom
| | - Andrew D. Morris
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom
| | - Markku Peltonen
- Chronic Disease Epidemiology and Prevention Unit, Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
| | - Per-Arne Svensson
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Jacobson
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Jan Borén
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lars Sjöström
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lena M. S. Carlsson
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Stefano Romeo
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical and Experimental Medicine, University of Catanzaro, Catanzaro, Italy
- * E-mail:
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164
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Perttilä J, Huaman-Samanez C, Caron S, Tanhuanpää K, Staels B, Yki-Järvinen H, Olkkonen VM. PNPLA3 is regulated by glucose in human hepatocytes, and its I148M mutant slows down triglyceride hydrolysis. Am J Physiol Endocrinol Metab 2012; 302:E1063-9. [PMID: 22338072 DOI: 10.1152/ajpendo.00125.2011] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Liver fat is increased in carriers of the minor G allele in rs738409 (I148M amino acid substitution) in patatin-like phospholipase domain-containing 3 (PNPLA3)/adiponutrin. We studied transcriptional regulation of PNPLA3 in immortalized human hepatocytes (IHH) and human hepatoma cells (HuH7) and the impact of PNPLA3 I148M mutant on hepatocyte triglyceride metabolism. Studies in IHH showed that silencing of the carbohydrate response element-binding protein (ChREBP) abolished induction of PNPLA3 mRNA by glucose. Glucose-dependent binding of ChREBP to a newly identified carbohydrate response element in the PNPLA3 promoter was demonstrated by chromatin immunoprecipitation. Adenoviral overexpression of mouse ChREBP in IHH failed to induce PNPLA3 mRNA. [(3)H]acetate or [(3)H]oleate incorporation with 1-h pulse labeling or 18-h [(3)H]oleate labeling in HuH7 cells showed no effect of PNPLA3 I148M on triglyceride (TG) synthesis in the absence of free fatty acid (FFA) loading. Increased [(3)H]oleate accumulation into triglycerides in I148M-expressing cells was observed after 18 h of labeling in the presence of 200 μM FFA-albumin complexes. This was accompanied by increased PNPLA3 protein levels. The rate of hydrolysis of [(3)H]TG during lipid depletion was decreased significantly by PNPLA3 I148M. Our results suggest that PNPLA3 is regulated in human hepatocytes by glucose via ChREBP. PNPLA3 I148M enhances cellular accumulation of [(3)H]TG in the presence of excess FFA, which is known to stabilize PNPLA3 protein. These data do not exclude an effect of PNPLA3 I148M on hepatocyte lipogenesis but show that the mutant increases the stability of triglycerides.
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Affiliation(s)
- Julia Perttilä
- Minerva Foundation Institute for Medical Research, Helsinki, Finland.
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165
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Kumari M, Schoiswohl G, Chitraju C, Paar M, Cornaciu I, Rangrez AY, Wongsiriroj N, Nagy HM, Ivanova PT, Scott SA, Knittelfelder O, Rechberger GN, Birner-Gruenberger R, Eder S, Brown HA, Haemmerle G, Oberer M, Lass A, Kershaw EE, Zimmermann R, Zechner R. Adiponutrin functions as a nutritionally regulated lysophosphatidic acid acyltransferase. Cell Metab 2012; 15:691-702. [PMID: 22560221 PMCID: PMC3361708 DOI: 10.1016/j.cmet.2012.04.008] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 02/17/2012] [Accepted: 04/10/2012] [Indexed: 12/12/2022]
Abstract
Numerous studies in humans link a nonsynonymous genetic polymorphism (I148M) in adiponutrin (ADPN) to various forms of fatty liver disease and liver cirrhosis. Despite its high clinical relevance, the molecular function of ADPN and the mechanism by which I148M variant affects hepatic metabolism are unclear. Here we show that ADPN promotes cellular lipid synthesis by converting lysophosphatidic acid (LPA) into phosphatidic acid. The ADPN-catalyzed LPA acyltransferase (LPAAT) reaction is specific for LPA and long-chain acyl-CoAs. Wild-type mice receiving a high-sucrose diet exhibit substantial upregulation of Adpn in the liver and a concomitant increase in LPAAT activity. In Adpn-deficient mice, this diet-induced increase in hepatic LPAAT activity is reduced. Notably, the I148M variant of human ADPN exhibits increased LPAAT activity leading to increased cellular lipid accumulation. This gain of function provides a plausible biochemical mechanism for the development of liver steatosis in subjects carrying the I148M variant.
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Affiliation(s)
- Manju Kumari
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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166
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Hyysalo J, Stojkovic I, Kotronen A, Hakkarainen A, Sevastianova K, Makkonen J, Lundbom N, Rissanen A, Krauss RM, Melander O, Orho-Melander M, Yki-Järvinen H. Genetic variation in PNPLA3 but not APOC3 influences liver fat in non-alcoholic fatty liver disease. J Gastroenterol Hepatol 2012; 27:951-6. [PMID: 22141340 DOI: 10.1111/j.1440-1746.2011.07045.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIM A recent study in Indian subjects suggested common variants in apolipoprotein C3 (APOC3) (T-455C at rs2854116 and C-482T at rs2854117) to contribute to non-alcoholic fatty liver disease (NAFLD), plasma apoC3 and triglyceride concentrations. Our aim was to determine the contribution of genetic variation in APOC3 on liver fat content and plasma triglyceride and apoC3 concentrations in a larger European cohort. METHODS A total of 417 Finnish individuals were genotyped for rs2854116 and rs2854117 in APOC3 and the known rs738409 in patatin-like phospholipase domain-containing protein 3 (PNPLA3) influencing liver fat. Plasma apoC3 concentration was measured enzymatically, and liver fat by proton magnetic resonance spectroscopy. RESULTS APOC3 wild-type homozygotes and variant allele (T-455C or C-482T or both) carriers did not differ with regard to liver fat, apoC3 concentrations, triglyceride-, high density lipoprotein-, fasting plasma glucose, insulin-, alanine aminotransferase- and aspartate aminotransferase-concentrations, nor was there a difference in prevalence of NAFLD. In contrast, carriers of the PNPLA3 GG genotype at rs738409 had a 2.7-fold (median 11.3%) higher liver fat than those with the CC (median 4.2%) genotype. The PNPLA3 rs738409 was also an independent predictor of liver fat, together with age, gender, and body mass index. CONCLUSION Genetic variants in PNPLA3 but not APOC3 contribute to the variance in liver fat content due to NAFLD.
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Affiliation(s)
- Jenni Hyysalo
- Department of Medicine, Division of Diabetes, Helsinki University Central Hospital, Finland
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167
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Samuel VT, Shulman GI. Mechanisms for insulin resistance: common threads and missing links. Cell 2012; 148:852-71. [PMID: 22385956 DOI: 10.1016/j.cell.2012.02.017] [Citation(s) in RCA: 1495] [Impact Index Per Article: 124.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 02/07/2023]
Abstract
Insulin resistance is a complex metabolic disorder that defies explanation by a single etiological pathway. Accumulation of ectopic lipid metabolites, activation of the unfolded protein response (UPR) pathway, and innate immune pathways have all been implicated in the pathogenesis of insulin resistance. However, these pathways are also closely linked to changes in fatty acid uptake, lipogenesis, and energy expenditure that can impact ectopic lipid deposition. Ultimately, these cellular changes may converge to promote the accumulation of specific lipid metabolites (diacylglycerols and/or ceramides) in liver and skeletal muscle, a common final pathway leading to impaired insulin signaling and insulin resistance.
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Affiliation(s)
- Varman T Samuel
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510, USA.
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168
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Genetic variation in the peroxisome proliferator activated receptor-gamma gene is associated with histologically advanced NAFLD. Dig Dis Sci 2012; 57:952-7. [PMID: 22160635 DOI: 10.1007/s10620-011-1994-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/22/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND The peroxisome proliferator activated receptor-gamma (PPARG) is a nuclear receptor that regulates adipocyte differentiation, insulin sensitivity and lipid metabolism, thus, it represents a good candidate gene for non-alcoholic fatty liver disease (NAFLD). PURPOSE AND METHOD We investigated the association of two PPARG variants (Pro12Ala and C1431T) with NAFLD and its histological features. DNA was extracted from 274 archived, formalin-fixed liver biopsy specimens from 212 patients with NAFLD and 62 controls with normal liver histology. RESULTS Individual SNPs did not show significant association with NAFLD or its histological features. A haplotype comprised of both minor alleles (GT) was less enriched whereas a haplotype comprised of the two major alleles (CC) was more enriched in subjects with NAFLD compared to controls [9.3% vs. 28.1% for GT (P = 0.001, OR 0.26 (range 0.14-0.48) and 80.4% vs. 64.8% for CC (P = 0.037, OR 2.23 (range 1.30-3.81)]. Both haplotypes were significantly associated with steatosis and fibrosis. The GT haplotype was also associated with lobular inflammation. CONCLUSIONS Genetic variation in PPARG is associated with NAFLD, and the GT haplotype is associated with inflammatory and fibrotic changes that denote histologically advanced NAFLD.
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169
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Cusi K. Role of obesity and lipotoxicity in the development of nonalcoholic steatohepatitis: pathophysiology and clinical implications. Gastroenterology 2012; 142:711-725.e6. [PMID: 22326434 DOI: 10.1053/j.gastro.2012.02.003] [Citation(s) in RCA: 620] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 01/04/2012] [Accepted: 02/02/2012] [Indexed: 02/07/2023]
Abstract
As obesity reaches epidemic proportions, nonalcoholic fatty liver disease (NAFLD) is becoming a frequent cause of patient referral to gastroenterologists. There is a close link between dysfunctional adipose tissue in NAFLD and common conditions such as metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. This review focuses on the pathophysiology of interactions between adipose tissue and target organs in obesity and the resulting clinical implications for the management of nonalcoholic steatohepatitis. The release of fatty acids from dysfunctional and insulin-resistant adipocytes results in lipotoxicity, caused by the accumulation of triglyceride-derived toxic metabolites in ectopic tissues (liver, muscle, pancreatic beta cells) and subsequent activation of inflammatory pathways, cellular dysfunction, and lipoapoptosis. The cross talk between dysfunctional adipocytes and the liver involves multiple cell populations, including macrophages and other immune cells, that in concert promote the development of lipotoxic liver disease, a term that more accurately describes the pathophysiology of nonalcoholic steatohepatitis. At the clinical level, adipose tissue insulin resistance contributes to type 2 diabetes mellitus and cardiovascular disease. Treatments that rescue the liver from lipotoxicity by restoring adipose tissue insulin sensitivity (eg, significant weight loss, exercise, thiazolidinediones) or preventing activation of inflammatory pathways and oxidative stress (ie, vitamin E, thiazolidinediones) hold promise in the treatment of NAFLD, although their long-term safety and efficacy remain to be established. Better understanding of pathways that link dysregulated adipose tissue, metabolic dysfunction, and liver lipotoxicity will result in improvements in the clinical management of these challenging patients.
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Affiliation(s)
- Kenneth Cusi
- Division of Endocrinology, Diabetes and Metabolism, University of Florida, Gainesville, Florida 32610-0226, USA.
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170
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Farrell GC, van Rooyen D, Gan L, Chitturi S. NASH is an Inflammatory Disorder: Pathogenic, Prognostic and Therapeutic Implications. Gut Liver 2012; 6:149-71. [PMID: 22570745 PMCID: PMC3343154 DOI: 10.5009/gnl.2012.6.2.149] [Citation(s) in RCA: 283] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 01/18/2012] [Indexed: 12/12/2022] Open
Abstract
While non-alcoholic fatty liver disease (NAFLD) is highly prevalent (15% to 45%) in modern societies, only 10% to 25% of cases develop hepatic fibrosis leading to cirrhosis, end-stage liver disease or hepatocellular carcinoma. Apart from pre-existing fibrosis, the strongest predictor of fibrotic progression in NAFLD is steatohepatitis or non-alcoholic steatohepatitis (NASH). The critical features other than steatosis are hepatocellular degeneration (ballooning, Mallory hyaline) and mixed inflammatory cell infiltration. While much is understood about the relationship of steatosis to metabolic factors (over-nutrition, insulin resistance, hyperglycemia, metabolic syndrome, hypoadiponectinemia), less is known about inflammatory recruitment, despite its importance for the perpetuation of liver injury and fibrogenesis. In this review, we present evidence that liver inflammation has prognostic significance in NAFLD. We then consider the origins and components of liver inflammation in NASH. Hepatocytes injured by toxic lipid molecules (lipotoxicity) play a central role in the recruitment of innate immunity involving Toll-like receptors (TLRs), Kupffer cells (KCs), lymphocytes and neutrophils and possibly inflammasome. The key pro-inflammatory signaling pathways in NASH are nuclear factor-kappa B (NF-κB) and c-Jun N-terminal kinase (JNK). The downstream effectors include adhesion molecules, chemokines, cytokines and the activation of cell death pathways leading to apoptosis. The upstream activators of NF-κB and JNK are more contentious and may depend on the experimental model used. TLRs are strong contenders. It remains possible that inflammation in NASH originates outside the liver and in the gut microbiota that prime KC/TLR responses, inflamed adipose tissue and circulating inflammatory cells. We briefly review these mechanistic considerations and project their implications for the effective treatment of NASH.
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Affiliation(s)
- Geoffrey C. Farrell
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
| | - Derrick van Rooyen
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
| | - Lay Gan
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
| | - Shivrakumar Chitturi
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
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171
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A case-control study on the effects of the apolipoprotein E genotypes in nonalcoholic fatty liver disease. Mol Biol Rep 2012; 39:7381-8. [PMID: 22350157 DOI: 10.1007/s11033-012-1570-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 01/25/2012] [Indexed: 12/15/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions being the most common cause of chronic liver disease in Western countries. The Apolipoprotein E (ApoE) gene has three major isoforms encoded by the ε2, ε3, and ε4 alleles, with the ε4 allele associated with hypercholesterolemia and the ε2 allele with the opposite effect. The role of apoE genotypes on NAFLD has been previously investigated with conflicting results. Our hospital-based case-control study conducted in Italy aims to explore the effect of the apoE genotypes on NAFLD risk and their effect on the clinical features of NAFLD patients. 310 NAFLD cases and 422 controls were genotyped for apoE. Adjusted odds ratios (ORs) and 95% confidence intervals (CI) from logistic regression were used to explore the relationship between NAFLD and apoE genotypes, as well as their interaction with selected demographic and lifestyle factors. ApoE ε4 allele carriers showed a statistically significant two-fold reduction of NAFLD risk (OR = 0.51, 95% CI: 0.28-0.93) compared with ε3 homozygotes. A statistically significant lower HDL cholesterol level was observed for ApoE ε4 carriers if compared with ε3/ε3 genotype or ApoE ε2 carriers with a nearly linear decreasing trend from ApoE ε2 to ApoE ε4 carriers. Our study reports for the first time a protective effect of the ε4 allele towards NAFLD that might be attributable to its role in the regulation of hepatic triglycerides rich very low-density lipoproteins secretion.
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172
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Rosendahl J, Tönjes A, Schleinitz D, Kovacs P, Wiegand J, Ruffert C, Jesinghaus M, Schober R, Herms M, Grützmann R, Schulz HU, Stickel F, Werner J, Bugert P, Blüher M, Stumvoll M, Böhm S, Berg T, Wittenburg H, Mössner J, te Morsche R, Derikx M, Keim V, Witt H, Drenth JPH. A common variant of PNPLA3 (p.I148M) is not associated with alcoholic chronic pancreatitis. PLoS One 2012; 7:e29433. [PMID: 22276112 PMCID: PMC3262779 DOI: 10.1371/journal.pone.0029433] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 11/28/2011] [Indexed: 12/19/2022] Open
Abstract
Background Chronic pancreatitis (CP) is an inflammatory disease that in some patients leads to exocrine and endocrine dysfunction. In industrialized countries the most common aetiology is chronic alcohol abuse. Descriptions of associated genetic alterations in alcoholic CP are rare. However, a common PNPLA3 variant (p.I148M) is associated with the development of alcoholic liver cirrhosis (ALC). Since, alcoholic CP and ALC share the same aetiology PNPLA3 variant (p.I148M) possibly influences the development of alcoholic CP. Methods Using melting curve analysis we genotyped the variant in 1510 patients with pancreatitis or liver disease (961 German and Dutch alcoholic CP patients, 414 German patients with idiopathic or hereditary CP, and 135 patients with ALC). In addition, we included in total 2781 healthy controls in the study. Results The previously published overrepresentation of GG-genotype was replicated in our cohort of ALC (p-value <0.0001, OR 2.3, 95% CI 1.6–3.3). Distributions of genotype and allele frequencies of the p.I148M variant were comparable in patients with alcoholic CP, idiopathic and hereditary CP and in healthy controls. Conclusions The absence of an association of PNPLA3 p.I148M with alcoholic CP seems not to point to a common pathway in the development of alcoholic CP and alcoholic liver cirrhosis.
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Affiliation(s)
- Jonas Rosendahl
- Division of Gastroenterology and Rheumatology, Department for Internal Medicine, Neurology and Dermatology, University of Leipzig, Leipzig, Germany.
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173
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Zain SM, Mohamed R, Mahadeva S, Cheah PL, Rampal S, Basu RC, Mohamed Z. A multi-ethnic study of a PNPLA3 gene variant and its association with disease severity in non-alcoholic fatty liver disease. Hum Genet 2012; 131:1145-52. [PMID: 22258181 PMCID: PMC3374090 DOI: 10.1007/s00439-012-1141-y] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 01/09/2012] [Indexed: 12/13/2022]
Abstract
The adiponutrin (PNPLA3) rs738409 polymorphism has been found to be associated with susceptibility to non-alcoholic fatty liver disease (NAFLD) in various cohorts. We further investigated the association of this polymorphism with non-alcoholic steatohepatitis (NASH) severity and with histological features of NAFLD. A total of 144 biopsy-proven NAFLD patients and 198 controls were genotyped for PNPLA3 gene polymorphism (rs738409 C>G). The biopsy specimens were histologically graded by a qualified pathologist. We observed an association of G allele with susceptibility to NAFLD in the pooled subjects (OR 2.34, 95% CI 1.69–3.24, p < 0.0001), and following stratification, in each of the three ethnic subgroups, namely Chinese, Indian and Malay (OR 1.94, 95% CI 1.12–3.37, p = 0.018; OR 3.51, 95% CI 1.69–7.26, p = 0.001 and OR 2.05, 95% CI 1.25–3.35, p = 0.005, respectively). The G allele is associated with susceptibility to NASH (OR 2.64, 95% CI 1.85–3.75, p < 0.0001), with NASH severity (OR 1.85, 95% CI 1.05–3.26, p = 0.035) and with presence of fibrosis (OR 1.95, 95% CI 1.17–3.26, p = 0.013) but not with simple steatosis nor with other histological parameters. Although the serum triglyceride level is significantly higher in NAFLD patients compared to controls, the G allele is associated with decreased level of triglycerides (p = 0.029) in the NAFLD patients. Overall, the rs738409 G allele is associated with severity of NASH and occurence of fibrosis in patients with NAFLD.
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Affiliation(s)
- Shamsul Mohd Zain
- The Pharmacogenomics Laboratory, Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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174
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Coleman RA, Mashek DG. Mammalian triacylglycerol metabolism: synthesis, lipolysis, and signaling. Chem Rev 2011; 111:6359-86. [PMID: 21627334 PMCID: PMC3181269 DOI: 10.1021/cr100404w] [Citation(s) in RCA: 206] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Rosalind A Coleman
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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175
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Gustavsson C, Soga T, Wahlström E, Vesterlund M, Azimi A, Norstedt G, Tollet-Egnell P. Sex-dependent hepatic transcripts and metabolites in the development of glucose intolerance and insulin resistance in Zucker diabetic fatty rats. J Mol Endocrinol 2011; 47:129-43. [PMID: 21673048 DOI: 10.1530/jme-11-0007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Male Zucker diabetic fatty (mZDF) rats spontaneously develop type 2 diabetes, whereas females only become diabetic when fed a diabetogenic high-fat diet (high-fat-fed female ZDF rat, HF-fZDF). The aim of this study was to investigate if differences in liver functions could provide clues to this sex difference. Non-diabetic obese fZDF rats were compared with either mZDF or HF-fZDF regarding hepatic molecular profiles, to single out those components that might be protective in the females. High-fat feeding in fZDF led to enhanced weight gain, increased blood glucose and insulin levels, reduced insulin sensitivity and a trend towards reduced glucose tolerance, indicative of a prediabetic state. mZDF rats were diabetic, with low levels of insulin, high levels of glucose, reduced insulin sensitivity and impaired glucose tolerance. Transcript profiling and capillary electrophoresis time-of-flight mass spectrometry were used to indentify hepatic transcripts and metabolites that might be related to this. Many diet-induced alterations in transcript and metabolite levels in female rats were towards a 'male-like' phenotype, including reduced lipogenesis, increased fatty acid (FA) oxidation and increased oxidative stress responses. Alterations detected at the level of hepatic metabolites, indicated lower capacity for glutathione (GSH) production in male rats, and higher GSH turnover in females. Taken together, this could be interpreted as if anabolic pathways involving lipogenesis and lipid output might limit the degree of FA oxidation and oxidative stress in female rats. Together with a greater capacity to produce GSH, these hepatic sex differences might contribute to the sex-different development of diabetes in ZDF rats.
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Affiliation(s)
- Carolina Gustavsson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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176
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Chang CY. Understanding the relationship between PNPLA3, NAFLD and insulin resistance: do ethnic differences bring more questions or more answers? Liver Int 2011; 31:1246-9. [PMID: 22093451 DOI: 10.1111/j.1478-3231.2011.02612.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 07/04/2011] [Indexed: 02/13/2023]
Affiliation(s)
- Charissa Y. Chang
- The Division of Liver Diseases; Department of Medicine; The Mount Sinai School of Medicine; New York; NY; USA
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177
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Trépo E, Gustot T, Degré D, Lemmers A, Verset L, Demetter P, Ouziel R, Quertinmont E, Vercruysse V, Amininejad L, Deltenre P, Le Moine O, Devière J, Franchimont D, Moreno C. Common polymorphism in the PNPLA3/adiponutrin gene confers higher risk of cirrhosis and liver damage in alcoholic liver disease. J Hepatol 2011; 55:906-12. [PMID: 21334404 DOI: 10.1016/j.jhep.2011.01.028] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 12/20/2010] [Accepted: 01/06/2011] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS A recent genome-wide association study identified genetic polymorphism (rs738409 C>G) in the PNPLA3/adiponutrin gene associated with liver steatosis. This variant has also been linked to increased risk of alcoholic liver disease (ALD) and cirrhosis in Mestizo Mexicans with excessive alcohol intake. Our aim was to study the influence of this polymorphism on European Caucasian patients with histologically suggestive ALD. METHODS Three-hundred-and-twenty-eight healthy controls and 330 ALD patients, among whom 265 had cirrhosis, were genotyped for the rs738409 polymorphism. We studied the impact of rs738409 on clinical and biological parameters, together with histological staging of steatosis and fibrosis. PNPLA3 messenger RNA (mRNA) levels were measured by quantitative real-time PCR according to the patient's phenotype. RESULTS The G-allele was significantly more frequent in ALD patients than in controls (odds ratio [OR] = 1.54, 95% confidence interval [CI] = 1.12-2.11 p = 0.008) and was, among ALD patients, significantly associated with steatosis (p = 0.048), fibrosis (p = 0.001), and greater risk of cirrhosis (p = 0.001). In multivariate analysis, rs738409 remained the strongest independent factor associated with risk of cirrhosis (OR = 2.08; 95% CI = 1.15-3.77; p = 0.02). Furthermore, the PNPLA3 mRNA liver expression level was significantly lower in patients with more advanced fibrosis (p = 0.03) and negatively correlated with the hepatic venous pressure gradient (r = -0.41, p = 0.006). CONCLUSIONS In European Caucasians, the rs738409 variant is associated with increased risk of ALD, liver damage, and cirrhosis. Further prospective studies are required to confirm these results and to evaluate the potential of PNPLA3 as both a predictor and a therapeutic target in ALD.
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Affiliation(s)
- Eric Trépo
- Department of Gastroenterology, Hepatopancreatology and Digestive Oncology, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
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Wang CW, Lin HY, Shin SJ, Yu ML, Lin ZY, Dai CY, Huang JF, Chen SC, Li SSL, Chuang WL. The PNPLA3 I148M polymorphism is associated with insulin resistance and nonalcoholic fatty liver disease in a normoglycaemic population. Liver Int 2011; 31:1326-31. [PMID: 21745282 DOI: 10.1111/j.1478-3231.2011.02526.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIMS The adiponutrin/patatin-like phospholipase-3 (PNPLA3) I148M polymorphism has recently been found to contribute to differences in hepatic lipid content. Nonalcoholic fatty liver disease (NAFLD) has recently been considered a hepatic component of insulin resistance and a risk factor in the emergence of type 2 diabetes. However, whether there is an association between PNPLA3 I148M and insulin resistance and NAFLD in a normoglycaemic population is still unknown. METHODS This study enrolled 156 normoglycaemic individuals with NAFLD and 723 controls. All participants received complete biochemical and clinical workups including liver ultrasonography. They were then genotyped for the PNPLA3 I148M polymorphism. RESULTS We found significant differences in the genotype and the dominant model of the PNPLA3 I148M polymorphism between the NAFLD groups and the controls (P=0.018 and P=0.01 respectively). Furthermore, there was a dose effect of the PNPLA3 I148M genotype, in that CG heterozygotes had a risk of NAFLD between CC and GG homozygotes [adjusted odds ratio (OR)=2.03, 95% confidence interval (CI)=1.23-3.375 for the GG genotype and adjusted OR=1.55, 95% CI=1.02-2.35 for the CG genotype]. The dominant model of the PNPLA3 I148M polymorphism showed higher waist circumference, fasting insulin, Homeostasis Model Assessment (HOMA-IR), alanine aminotransferase concentrations and ferritin level. Multivariate analysis showed the PNPLA3 I148M polymorphism to be independently and significantly associated with NAFLD in our normoglycaemic participants. CONCLUSION This study reports an association between the PNPLA3-I148M polymorphism and insulin resistance and NAFLD in a normoglycaemic population.
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Affiliation(s)
- Chih-Wen Wang
- Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan
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179
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Petit JM, Guiu B, Masson D, Duvillard L, Jooste V, Buffier P, Bouillet B, Brindisi MC, Robin I, Gambert P, Verges B, Cercueil JP, Hillon P. PNPLA3 polymorphism influences liver fibrosis in unselected patients with type 2 diabetes. Liver Int 2011; 31:1332-6. [PMID: 21745307 DOI: 10.1111/j.1478-3231.2011.02566.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
CONTEXT Recently, it has been shown that an allele in the adiponutrin (PNPLA3) gene was strongly associated with increased liver fat content (LFC) and liver fibrosis independent of visceral adiposity and insulin resistance. OBJECTIVE In this study, we set out to determine whether the PNPLA3 rs738409 polymorphism was associated with liver fibrosis in unselected patients with type 2 diabetes. DESIGN, SETTING AND PARTICIPANTS Two hundred and thirty-four patients with type 2 diabetes were included in this study. MAIN OUTCOME MEASURES LFC was evaluated using (1) H-MR spectroscopy; fibrosis was measured using the non-invasive FibroTest(®). RESULTS Advanced liver fibrosis (stage F2 or above) was observed in 10.2% of the patients while 149 (63.6%) patients had steatosis. The prevalence of steatosis and fibrosis was higher in minor G allele carriers than that in C allele homozygote carriers (70.3 vs 57.1%; P=0.04 and 14.7 vs 7.5%; P=0.07 respectively). In multivariate analysis, the predictive variables for advanced liver fibrosis were age (≥60) (P=0.005), sex (female) (P=0.004) and rs 738409 PNPLA3 polymorphism (P=0.01); body mass index (BMI) and LFC were not associated with liver fibrosis. CONCLUSIONS This study confirms that in patients with type 2 diabetes who were not selected for liver abnormalities, liver fibrosis was related to the rs738409 polymorphism independent of BMI or LFC.
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Affiliation(s)
- Jean M Petit
- Centre de Recherche, INSERM Unité 866, Université de Bourgogne, CHU du Bocage, Dijon, France.
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180
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Quiroga AD, Lehner R. Liver triacylglycerol lipases. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:762-9. [PMID: 21963564 DOI: 10.1016/j.bbalip.2011.09.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 09/14/2011] [Accepted: 09/15/2011] [Indexed: 12/20/2022]
Abstract
The hallmark of obesity and one of the key contributing factors to insulin resistance, type 2 diabetes and cardiovascular disease is excess triacylglycerol (TG) storage. In hepatocytes, excessive accumulation of TG is the common denominator of a wide range of clinicopathological entities known as nonalcoholic fatty liver disease, which can eventually progress to cirrhosis and associated complications including hepatic failure, hepatocellular carcinoma and death. A tight regulation between TG synthesis, hydrolysis, secretion and fatty acid oxidation is required to prevent lipid accumulation as well as lipid depletion from hepatocytes. Therefore, understanding the pathways that regulate hepatic TG metabolism is crucial for development of therapies to ameliorate pathophysiological conditions associated with excessive hepatic TG accumulation, including dyslipidemias, viral infection and atherosclerosis. This review highlights the physiological roles of liver lipases that degrade TG in cytosolic lipid droplets, endoplasmic reticulum, late endosomes/lysosomes and along the secretory route. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
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Affiliation(s)
- Ariel D Quiroga
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
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181
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Cold exposure down-regulates adiponutrin/PNPLA3 mRNA expression and affects its nutritional regulation in adipose tissues of lean and obese Zucker rats. Br J Nutr 2011; 107:1283-95. [PMID: 21914237 DOI: 10.1017/s000711451100434x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Adiponutrin/PNPLA3 is a protein highly produced in adipose tissue whose expression is under tight nutritional regulation. It possesses lipogenic/lipolytic capacity and, although adiponutrin polymorphisms are related to obesity, its physiological role is not clear. To help clarify its role, we studied the effect of acute cold exposure on adiponutrin mRNA expression in different adipose tissues of lean/obese Zucker rats subjected to feeding/fasting/refeeding. The effect of cold on the expression of key lipogenic enzymes and on uncoupling protein-1 (UCP1) was evaluated in selected adipose depots. Adiponutrin mRNA levels were also determined in the adipose tissue of isoprenaline-treated rats and in cultured adipocytes treated with noradrenaline, isoprenaline and a selective β3-adrenoceptor (AR) agonist. Adiponutrin expression was strongly down-regulated by cold in the different adipose depots in lean animals, while this down-regulation was impaired in obese rats. Adiponutrin pattern of expression in response to cold correlated positively with that of the lipogenic enzymes and negatively with UCP1 expression. Acute intraperitoneal administration of isoprenaline also produced a decrease in adiponutrin expression in adipose tissue. In vitro data suggest that adiponutrin's inhibitory effect could be mediated, at least in part, by the sympathetic system via β1/β2-AR. In addition, improvement in metabolic parameters related to obesity in cold-exposed animals was related to an improvement in adiponutrin nutritional regulation. Thus, cold inhibition of adiponutrin expression in adipose tissue (which correlates with the response of lipogenic enzymes) supports a physiological role for this protein in lipogenesis. Moreover, alterations in adiponutrin expression and regulation in adipose tissue are related to obesity.
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182
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Lomonaco R, Ortiz-Lopez C, Orsak B, Finch J, Webb A, Bril F, Louden C, Tio F, Cusi K. Role of ethnicity in overweight and obese patients with nonalcoholic steatohepatitis. Hepatology 2011; 54:837-45. [PMID: 21674556 DOI: 10.1002/hep.24483] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 05/28/2011] [Indexed: 12/13/2022]
Abstract
UNLABELLED The role of ethnicity in determining disease severity in nonalcoholic steatohepatitis (NASH) remains unclear. We recruited 152 patients with biopsy-proven NASH, 63% of whom were Hispanic and 37% of whom were Caucasian. Both groups were well matched for age, sex, and total body fat. We measured: (1) liver fat by magnetic resonance imaging and spectroscopy; (2) fasting plasma glucose, fasting plasma insulin (FPI), and free fatty acid (FFA) levels; (3) total body fat by dual energy x-ray absorptiometry (DXA); (4) liver and muscle insulin sensitivity (insulin clamp with 3-[(3)H] glucose); (5) insulin resistance at the level of the liver (fasting endogenous glucose production derived from 3-[(3)H] glucose infusion × FPI) and adipose tissue (fasting FFA × FPI). Liver fat was slightly, but not significantly, higher in Hispanic vs. Caucasian patients (27 ± 2% vs. 24 ± 2%, p = 0.16). However, this trend did not translate into worse liver steatosis, necroinflammation or fibrosis. Patients with NASH had severe hepatic, adipose tissue and muscle insulin resistance versus healthy subjects without NASH nonalcoholic fatty liver disease, but there were no differences between both ethnic groups on these parameters. However, Hispanics versus Caucasians with type 2 diabetes mellitus (T2DM) had a trend for worse hepatic/adipose tissue insulin resistance and fibrosis. CONCLUSION When Hispanic and Caucasian patients with NASH are well matched for clinical parameters, particularly for adiposity, slightly higher liver fat content is not associated with worse hepatic insulin resistance or more severe NASH on histology. Hispanic ethnicity does not appear to be a major determinant of disease severity in NASH, although those with diabetes may be at greater risk of fibrosis. Given the higher risk of T2DM in Hispanics, long-term studies are needed to define their risk of disease progression.
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Affiliation(s)
- Romina Lomonaco
- Division of Diabetes, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
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183
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Lau-Corona D, Kershenobich D, Gutierrez-Reyes G. The impact of genetic variability on liver disease in the Hispanic/Latin-American population. Autoimmunity 2011; 44:549-54. [PMID: 21864063 DOI: 10.3109/08916934.2011.592883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Liver cirrhosis is within the top 10 causes of death in Latin-American countries and recent evidence suggests that Hispanics in the USA have a more aggressive course of many types of liver disease and show lower response to treatment of hepatitis C compared with other ethnic groups. Although environmental factors are very important, they do not appear to fully account for the observed ethnic differences in the incidence of cirrhosis and progression rates. Genome-wide association studies have been a powerful tool to identify genetic variants that directly confer susceptibility to liver disease. Here, we review the current knowledge on genetic variants associated with the most common types of liver disease that may contribute to ancestry-related differences in disease progression and mortality.
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Affiliation(s)
- Dana Lau-Corona
- Department of Experimental Medicine, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Hospital General de México , Dr Balmis 148, Mexico City 02726 , Mexico.
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184
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Peter A, Kantartzis K, Machicao F, Machann J, Wagner S, Templin S, Königsrainer I, Königsrainer A, Schick F, Fritsche A, Häring HU, Stefan N. Visceral obesity modulates the impact of apolipoprotein C3 gene variants on liver fat content. Int J Obes (Lond) 2011; 36:774-82. [PMID: 21829161 DOI: 10.1038/ijo.2011.154] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE It has not been solved whether subjects carrying the minor alleles of the -455T>C or -482C>T single nucleotide polymorphisms (SNPs) in the apolipoprotein-C3-gene (APOC3) have an increased risk for developing fatty liver and insulin resistance. We investigated the relationships of the SNPs with hepatic APOC3 expression and hypothesized that visceral obesity may modulate the effects of these SNPs on liver fat and insulin sensitivity (IS). METHODS APOC3 mRNA expression and triglyceride content were determined in liver biopsies from 50 subjects. In a separate group (N=330) liver fat was measured by (1)H-magnetic resonance spectroscopy. IS was estimated during an oral glucose tolerance test (OGTT) and the euglycemic, hyperinsulinemic clamp (N=222). RESULTS APOC3 mRNA correlated positively with triglyceride content in liver biopsies (r=0.29, P=0.036). Carriers of the minor alleles (-455C and -482T) tended to have higher hepatic APOC3 mRNA expression (1.80 (0.45-3.56) vs 0.77 (0.40-1.64), P=0.09), but not higher triglyceride content (P=0.76). In 330 subjects the genotype did not correlate with liver fat (P=0.97) or IS (OGTT: P=0.41; clamp: P=0.99). However, a significant interaction of the genotype with waist circumference in determining liver fat was detected (P=0.02) in which minor allele carriers had higher liver fat only in the lowest tertile of waist circumference (P=0.01). In agreement, during a 9-month lifestyle intervention the minor allele carriers of the SNP -482C>T in the lowest tertile also had less decrease in liver fat (P=0.04). CONCLUSIONS APOC3 mRNA expression is increased in fatty liver and is regulated by SNPs in APOC3. The impact of the APOC3 SNPs on fatty liver is small and depends on visceral obesity.
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Affiliation(s)
- A Peter
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University of Tübingen, Otfried-Müller-Street 10, Tübingen, Germany
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185
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Anstee QM, Daly AK, Day CP. Genetic modifiers of non-alcoholic fatty liver disease progression. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1557-66. [PMID: 21840395 DOI: 10.1016/j.bbadis.2011.07.017] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/28/2011] [Accepted: 07/29/2011] [Indexed: 12/11/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is now recognised as the most common cause of liver dysfunction worldwide. However, whilst the majority of individuals who exhibit features of the metabolic syndrome including obesity and insulin resistance will develop steatosis, only a minority progress to steatohepatitis, fibrosis and cirrhosis. Subtle inter-patient genetic variations and environment interact to determine disease phenotype and influence progression. A decade after the sequencing of the human genome, the comprehensive study of genomic variation offers new insights into the modifier genes, pathogenic mechanisms and is beginning to suggest novel therapeutic targets. We review the current status of the field with particular focus on advances from recent genome-wide association studies.
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Affiliation(s)
- Quentin M Anstee
- Liver Research Group, Instiutte of Cellular Medicine, Teh Medical School, Newcastle University, Framlington Place, Newcaltle-upon-Type, NE2 4HHK, UK
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186
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Krawczyk M, Grünhage F, Zimmer V, Lammert F. Variant adiponutrin (PNPLA3) represents a common fibrosis risk gene: non-invasive elastography-based study in chronic liver disease. J Hepatol 2011; 55:299-306. [PMID: 21168459 DOI: 10.1016/j.jhep.2010.10.042] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 10/17/2010] [Accepted: 10/25/2010] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Recent genome-wide association studies have identified the variant p.I148M of the adiponutrin gene PNPLA3 as a risk factor for developing severe forms of non-alcoholic and alcoholic liver diseases. The risk allele confers an increased risk for fatty liver disease and elevated serum aminotransferase activities reflecting liver injury. In the current elastography-based study, we investigate variant adiponutrin as genetic determinant of liver fibrosis, the hallmark of all chronic liver diseases. METHODS In this observational cross-sectional study, we staged 899 patients with different chronic liver diseases non-invasively by transient elastography (Fibroscan) and genotyped them for variant adiponutrin (rs738409) by PCR-based assays. A subgroup of 229 patients consented to percutaneous liver biopsy, validating the accuracy of elastography in staging fibrosis (ρ=0.743, p<0.01). RESULTS Carriers of distinct p.I148M adiponutrin genotypes display significant (p=0.017) differences in liver stiffness determined by elastography. In particular, individuals carrying the allele [G] are at higher risk of developing liver cirrhosis defined by stiffness values ≥13.0kPa (OR=1.56, p=0.005). Of note, the PNPLA3 risk variant advances fibrosis in the total cohort as well as in the subgroups of patients with viral hepatitis and non-viral liver diseases and contributes 16% of the total cirrhosis risk. CONCLUSIONS The adiponutrin risk variant is a common genetic determinant of progressive liver fibrosis. Our results underpin non-invasive follow-up for individuals with chronic liver disease at-risk for developing advanced fibrosis and cirrhosis.
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Affiliation(s)
- Marcin Krawczyk
- Department of Medicine II, Saarland University Hospital, Homburg, Germany
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187
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Vernon G, Baranova A, Younossi ZM. Systematic review: the epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults. Aliment Pharmacol Ther 2011; 34:274-85. [PMID: 21623852 DOI: 10.1111/j.1365-2036.2011.04724.x] [Citation(s) in RCA: 2199] [Impact Index Per Article: 169.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease, and its worldwide prevalence continues to increase with the growing obesity epidemic. This study assesses the epidemiology of NAFLD in adults based on clinical literature published over the past 30 years. AIM To review epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults based on clinical literature published over the past 30 years. METHODS An in-depth search of PubMed (1980-2010) was based on five search terms: 'non-alcoholic fatty liver disease' OR 'non-alcoholic steatohepatitis' OR 'fatty liver' OR 'steatosis' AND 'incidence' [MeSH Terms] OR 'prevalence' [MeSH Terms] OR 'natural history'. Studies of paediatric cohorts were excluded. Articles were categorised by topic and summarised, noting generalisations concerning their content. RESULTS Four study categories included NAFLD incidence, prevalence, risk factors and natural history. Studies related to NAFLD prevalence and incidence indicate that the diagnosis is heterogeneous and relies on a variety of assessment tools, including liver biopsy, radiological tests such as ultrasonography, and blood testing such as liver enzymes. The prevalence of NAFLD is highest in populations with pre-existing metabolic conditions such as obesity and type II diabetes. Many studies investigating the natural history of NAFLD verify the progression from NASH to advanced fibrosis and hepatocellular carcinoma. CONCLUSIONS Non-alcoholic fatty liver disease is the most common cause of elevated liver enzymes. Within the NAFLD spectrum, only NASH progresses to cirrhosis and hepatocellular carcinoma. With the growing epidemic of obesity, the prevalence and impact of NAFLD continues to increase, making NASH potentially the most common cause of advanced liver disease in coming decades.
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Affiliation(s)
- G Vernon
- Department of Medicine, Center for Liver Diseases, Inova Fairfax Hospital, Falls Church, VA 22042, USA
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188
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Qiao A, Liang J, Ke Y, Li C, Cui Y, Shen L, Zhang H, Cui A, Liu X, Liu C, Chen Y, Zhu Y, Guan Y, Fang F, Chang Y. Mouse patatin-like phospholipase domain-containing 3 influences systemic lipid and glucose homeostasis. Hepatology 2011; 54:509-21. [PMID: 21547936 DOI: 10.1002/hep.24402] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 04/20/2011] [Indexed: 12/11/2022]
Abstract
UNLABELLED Human patatin-like phospholipase domain-containing 3 (PNPLA3) is associated with increased liver fat content and liver injury. Here, we show that nutritional status regulates PNPLA3 gene expression in the mouse liver. Sterol response element binding protein-1 (SREBP-1) activated PNPLA3 gene transcription via sterol regulatory elements (SREs) mapped to the promoter region. Chromatin immunoprecipitation and electrophoretic mobility shift assays confirmed that SREBP-1 proteins bound to the identified SREs. Furthermore, SREBP-1c mediated the insulin and liver X receptor agonist TO901317-dependent induction of PNPLA3 gene expression in hepatocytes. Adenovirus-mediated overexpression of mouse PNPLA3 increased intracellular triglyceride content in primary hepatocytes, and knockdown of PNPLA3 suppressed the ability of SREBP-1c to stimulate lipid accumulation in hepatocytes. Finally, the overexpression of PNPLA3 in mouse liver increased the serum triglyceride level and impaired glucose tolerance; in contrast, the knockdown of PNPLA3 in db/db mouse liver improved glucose tolerance. CONCLUSION Our data suggest that mouse PNPLA3, which is a lipogenic gene directly targeted by SREBP-1, promotes lipogenesis in primary hepatocytes and influences systemic lipid and glucose metabolism.
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Affiliation(s)
- Aijun Qiao
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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189
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Sevastianova K, Kotronen A, Gastaldelli A, Perttilä J, Hakkarainen A, Lundbom J, Suojanen L, Orho-Melander M, Lundbom N, Ferrannini E, Rissanen A, Olkkonen VM, Yki-Järvinen H. Genetic variation in PNPLA3 (adiponutrin) confers sensitivity to weight loss-induced decrease in liver fat in humans. Am J Clin Nutr 2011; 94:104-11. [PMID: 21525193 DOI: 10.3945/ajcn.111.012369] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The rs738409 C→G single nucleotide polymorphism in the patatin-like phospholipase domain-containing 3 (PNPLA3; adiponutrin) leads to a missense mutation (I148M), which is associated with increased liver fat but not insulin resistance. The I148M mutation impedes triglyceride hydrolysis in vitro, and its carriers have an increased risk of developing severe liver disease. OBJECTIVE We explored whether the rs738409 PNPLA3 G allele influences the ability of weight loss to decrease liver fat or change insulin sensitivity. DESIGN We recruited 8 subjects who were homozygous for the rs738409 PNPLA3 G allele (PNPLA3-148MM) and 10 who were homozygous for the rs738409 PNPLA3 C allele (PNPLA3-148II). To allow comparison of changes in liver fat, the groups were matched with respect to baseline age, sex, body mass index, and liver fat. The subjects were placed on a hypocaloric low-carbohydrate diet for 6 d. Liver fat content (proton magnetic resonance spectroscopy), whole-body insulin sensitivity of glucose metabolism (euglycemic clamp technique), and lipolysis ([(2)H(5)]glycerol infusion) were measured before and after the diet. RESULTS At baseline, fasting serum insulin and C-peptide concentrations were significantly lower in the PNPLA3-148MM group than in the PNPLA3-148II group, as predicted by study design. Weight loss was not significantly different between groups (PNPLA3-148MM: -3.1 ± 0.5 kg; PNPLA3-148II: -3.1 ± 0.4 kg). Liver fat decreased by 45% in the PNPLA3-148MM group (P < 0.001) and by 18% in the PNPLA3-148II group (P < 0.01). CONCLUSION Weight loss is effective in decreasing liver fat in subjects who are homozygous for the rs738409 PNPLA3 G or C allele. This trial was registered at www.hus.fi as 233775.
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190
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Long JZ, Cravatt BF. The metabolic serine hydrolases and their functions in mammalian physiology and disease. Chem Rev 2011; 111:6022-63. [PMID: 21696217 DOI: 10.1021/cr200075y] [Citation(s) in RCA: 299] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jonathan Z Long
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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191
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Li DY, Lin LJ, Zheng CQ. Advances in understanding the role of PNPLA3 in the pathogenesis of non-alcoholic fatty liver disease. Shijie Huaren Xiaohua Zazhi 2011; 19:1796-1801. [DOI: 10.11569/wcjd.v19.i17.1796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The incidence of non-alcoholic fatty liver disease (NAFLD) is rising worldwide. Investigation of genes involved in the pathogenesis of NAFLD is significant for replenishing treatment scheme and improving prognosis. Multiple studies have established a correlation between patatin-like phospholipase domain-containing 3 (PNPLA3) gene mutation and the pathogenesis of NAFLD, suggesting that PNPLA3 may affect lipid metabolism. However, the precise mechanism remains to be elucidated. Some researchers believed that PNPLA3 as a patatin-like protein might have triglyceride hydrolysis activity and therefore affect fat metabolism in the liver, while some others thought that PNPLA3 mutation might interfere with the lipid transfer process. In this paper, we give an overview of the PNPLA3 gene and its expression, and explore the correlation between PNPLA3 gene mutation and the pathogenesis of NAFLD.
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192
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Cox AJ, Wing MR, Carr JJ, Hightower RC, Smith SC, Xu J, Wagenknecht LE, Bowden DW, Freedman BI. Association of PNPLA3 SNP rs738409 with liver density in African Americans with type 2 diabetes mellitus. DIABETES & METABOLISM 2011; 37:452-5. [PMID: 21665509 DOI: 10.1016/j.diabet.2011.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 05/05/2011] [Accepted: 05/07/2011] [Indexed: 12/25/2022]
Abstract
AIM Non-alcoholic fatty liver disease (NAFLD) is commonly diagnosed in patients with obesity and type 2 diabetes mellitus (T2DM), and has been associated with the single nucleotide polymorphism (SNP) rs738409 in the PNPLA3 gene. This association remains to be investigated in African Americans with T2DM, a group at lower risk for hepatic steatosis relative to European Americans with T2DM. METHODS We examined 422 African Americans with T2DM (40.3% male; age: 56.4±9.6 years; Body Mass Index: 35.2±8.2 kg/m(2)), all with measures of liver density reflecting hepatic fat content on abdominal computed tomography, and blood glucose and lipid profiles. Associations between rs738409 and phenotypes of interest were determined using SOLAR, assuming an additive model of inheritance with covariates age, sex, BMI and use of lipid-lowering medications. RESULTS Mean±SD liver density was 55.4±10.2 Hounsfield Units. SNP rs738409 in PNPLA3 was significantly associated with liver density (P=0.0075) and hepatic steatosis (P=0.0350), but not with blood glucose, HbA(1c), total cholesterol, triglycerides, high-density or low-density lipoprotein levels or liver function tests (P=0.15-0.96). CONCLUSION These findings provide evidence that the PNPLA3 SNP rs738409 contributes to risk for increased liver fat content in African Americans with T2DM, an effect that appears to be independent from serum lipids. Although African Americans are less susceptible to fatty liver than European Americans, PNPLA3 appears to be a risk locus for hepatic steatosis in diabetic African Americans.
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Affiliation(s)
- A J Cox
- Center for Human Genomics, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Sookoian S, Pirola CJ. Meta-analysis of the influence of I148M variant of patatin-like phospholipase domain containing 3 gene (PNPLA3) on the susceptibility and histological severity of nonalcoholic fatty liver disease. Hepatology 2011; 53:1883-94. [PMID: 21381068 DOI: 10.1002/hep.24283] [Citation(s) in RCA: 698] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 02/21/2011] [Indexed: 12/12/2022]
Abstract
UNLABELLED Our objective was to estimate the strength of the effect of the I148M (rs738409 C/G) patatin-like phospholipase domain containing 3 (PNPLA3) variant on nonalcoholic fatty liver (NAFLD) and disease severity across different populations. We performed a systematic review by a meta-analysis; literature searches identified 16 studies. Our results showed that rs738409 exerted a strong influence not only on liver fat accumulation (GG homozygous showed 73% higher lipid fat content when compared with CC ones, data from 2,937 subjects; P < 1 × 10(-9) ), but also on the susceptibility of a more aggressive disease (GG homozygous had 3.24-fold greater risk of higher necroinflammatory scores and 3.2-fold greater risk of developing fibrosis when compared with CC homozygous; P < 1 × 10(-9) ; data from 1,739 and 2,251 individuals, respectively). Nonalcoholic steatohepatitis (NASH) was more frequently observed in GG than CC homozygous (odds ratio [OR] 3.488, 95% confidence interval [CI] 1.859-6.545, random model; P < 2 × 10(-4) ; data from 2,124 patients). Evaluation of the risk associated with heterozygosity for the variant suggests that the additive genetic model best explains the effect of rs738409 on the susceptibility to develop NAFLD. Nevertheless, carrying two G alleles does not seem to increase the risk of severe histological features. Meta-regression showed a negative correlation between male sex and the effect of rs738409 on liver fat content (slope: -2.45 ± 1.04; P < 0.02). The rs738409 GG genotype versus the CC genotype was associated with a 28% increase in serum alanine aminotransferase levels. CONCLUSION By summarizing the amount of evidence, this study provided unequivocal evidence of rs738409 as a strong modifier of the natural history of NAFLD in different populations around the world.
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Affiliation(s)
- Silvia Sookoian
- Department of Clinical and Molecular Hepatology, Institute of Medical Research A Lanari-IDIM, University of Buenos Aires-National-Council of Scientific and Technological Research (CONICET), Ciudad Autónoma de Buenos Aires, Argentina.
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194
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Lin YC, Chang PF, Hu FC, Yang WS, Chang MH, Ni YH. A common variant in the PNPLA3 gene is a risk factor for non-alcoholic fatty liver disease in obese Taiwanese children. J Pediatr 2011; 158:740-4. [PMID: 21168155 DOI: 10.1016/j.jpeds.2010.11.016] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 09/07/2010] [Accepted: 11/02/2010] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To test the hypothesis that the presence of the PNPLA3 rs738409 G allele would increase the susceptibility of non-alcoholic fatty liver disease (NAFLD) in obese Taiwanese children. STUDY DESIGN A total of 520 obese children aged 6-18 years were recruited. Their PNPLA3 rs738409 genotypes-CC, CG, or GG-were detected by the 5'-nuclease assay. The effects of the PNPLA3 rs738409 G allele on pediatric NAFLD were evaluated based on liver ultrasonography findings and mean serum alanine aminotransferase levels in these children. RESULTS NAFLD was present in 19.6% of the obese children. In comparison to the subjects with CC alleles, the risk of NAFLD was increased by 2.96-fold (95% CI, 1.57 to 5.59, P = .0008) in the subjects with CG alleles and by 5.84-fold (95% CI, 2.59 to 13.16; P < .0001) in those with GG alleles. Variant PNPLA3 rs738409 genotypes were associated with increases in mean serum alanine aminotransferase level of 4.77 IU/L (P = .0435) in subjects with CG alleles and of 10.86 IU/L (P < .0001) in those with GG alleles compared with subjects with CC alleles. CONCLUSIONS The variant PNPLA3 rs738409 genotypes increased the risk of NAFLD in our population of obese Taiwanese children. The effect of the G allele on pediatric NAFLD followed a dominant genetic model.
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Affiliation(s)
- Yu-Cheng Lin
- Department of Pediatrics, Far Eastern Memorial Hospital, Banqiao City, Taipei County, Taiwan
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195
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Harmon RC, Tiniakos DG, Argo CK. Inflammation in nonalcoholic steatohepatitis. Expert Rev Gastroenterol Hepatol 2011; 5:189-200. [PMID: 21476914 DOI: 10.1586/egh.11.21] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) describes a range of disorders characterized by excess accumulation of triglyceride within the liver. While simple steatosis may be clinically stable, nonalcoholic steatohepatitis (NASH) can be progressive. Inflammation is believed to be the driving force behind NASH and the progression to fibrosis and subsequent cirrhosis. This article will review and interpret the current literature in an attempt to expand our understanding of the environmental and genetic causes of inflammation and its effects in NAFLD.
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Affiliation(s)
- R Christopher Harmon
- Division of Gastroenterology and Hepatology, University of Virginia Health System, Box 800708, Charlottesville, VA 22908, USA.
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196
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Genome-wide association analysis identifies variants associated with nonalcoholic fatty liver disease that have distinct effects on metabolic traits. PLoS Genet 2011; 7:e1001324. [PMID: 21423719 PMCID: PMC3053321 DOI: 10.1371/journal.pgen.1001324] [Citation(s) in RCA: 722] [Impact Index Per Article: 55.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 02/02/2011] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) clusters in families, but the only known common genetic variants influencing risk are near PNPLA3. We sought to identify additional genetic variants influencing NAFLD using genome-wide association (GWA) analysis of computed tomography (CT) measured hepatic steatosis, a non-invasive measure of NAFLD, in large population based samples. Using variance components methods, we show that CT hepatic steatosis is heritable (∼26%–27%) in family-based Amish, Family Heart, and Framingham Heart Studies (n = 880 to 3,070). By carrying out a fixed-effects meta-analysis of genome-wide association (GWA) results between CT hepatic steatosis and ∼2.4 million imputed or genotyped SNPs in 7,176 individuals from the Old Order Amish, Age, Gene/Environment Susceptibility-Reykjavik study (AGES), Family Heart, and Framingham Heart Studies, we identify variants associated at genome-wide significant levels (p<5×10−8) in or near PNPLA3, NCAN, and PPP1R3B. We genotype these and 42 other top CT hepatic steatosis-associated SNPs in 592 subjects with biopsy-proven NAFLD from the NASH Clinical Research Network (NASH CRN). In comparisons with 1,405 healthy controls from the Myocardial Genetics Consortium (MIGen), we observe significant associations with histologic NAFLD at variants in or near NCAN, GCKR, LYPLAL1, and PNPLA3, but not PPP1R3B. Variants at these five loci exhibit distinct patterns of association with serum lipids, as well as glycemic and anthropometric traits. We identify common genetic variants influencing CT–assessed steatosis and risk of NAFLD. Hepatic steatosis associated variants are not uniformly associated with NASH/fibrosis or result in abnormalities in serum lipids or glycemic and anthropometric traits, suggesting genetic heterogeneity in the pathways influencing these traits. NAFLD is a spectrum of disease that ranges from steatosis to steatohepatitis (nonalcoholic steatohepatitis or NASH: inflammation around the fat) to fibrosis/cirrhosis. Hepatic steatosis can be measured non-invasively using computed tomography (CT) whereas NASH/fibrosis is assessed histologically. The genetic underpinnings of NAFLD remain to be determined. Here we estimate that 26%–27% of the variation in CT measured hepatic steatosis is heritable or genetic. We identify three variants near PNPLAL3, NCAN, and PPP1R3B that associate with CT hepatic steatosis and show that variants in or near NCAN, GCKR, LYPLAL1, and PNPLA3, but not PPP1R3B, associate with histologic lobular inflammation/fibrosis. Variants in or near NCAN, GCKR, and PPP1R3B associate with altered serum lipid levels, whereas those in or near LYPLAL1 and PNPLA3 do not. Variants near GCKR and PPP1R3B also affect glycemic traits. Thus, we show that NAFLD is genetically influenced and expand the number of common genetic variants that associate with this trait. Our findings suggest that development of hepatic steatosis, NASH/fibrosis, or abnormalities in metabolic traits are probably influenced by different metabolic pathways that may represent distinct therapeutic targets.
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197
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Wagenknecht LE, Palmer ND, Bowden DW, Rotter JI, Norris JM, Ziegler J, Chen YDI, Haffner S, Scherzinger A, Langefeld CD. Association of PNPLA3 with non-alcoholic fatty liver disease in a minority cohort: the Insulin Resistance Atherosclerosis Family Study. Liver Int 2011; 31:412-6. [PMID: 21281435 PMCID: PMC3703938 DOI: 10.1111/j.1478-3231.2010.02444.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent condition, particularly among Hispanic Americans. A genetic variant in PNPLA3 (rs738409) has been identified as a strong predictor of hepatic fat content. AIMS To confirm the association of this variant with NAFLD in two minority cohorts, Hispanic Americans and African Americans, in whom liver density was quantified by computed tomography (CT). METHODS This analysis was conducted in the Insulin Resistance Atherosclerosis (IRAS) Family Study. Participants were recruited from the general community and included 843 Hispanic American and 371 African American adults aged 18-81 years. A single variant in PNPLA3 (rs738409) was genotyped. Liver density was calculated in Hounsfield Units from abdominal CT scans. RESULTS Single nucleotide polymorphism (SNP) rs738409 was strongly associated with reduced liver density (i.e. NAFLD) in Hispanic Americans (1.18 × 10⁻⁹) and in African Americans (P=4.99 × 10⁻⁶). The association followed an additive genetic model with the G allele conferring risk. The allele was two times more common in Hispanic Americans than in African Americans (40 vs 19%), consistent with the greater prevalence of NAFLD in Hispanic Americans (24 vs 9%). The SNP explained 4.4 and 5.6% of the variance of the adjusted liver density outcome in Hispanic Americans and African Americans, respectively. CONCLUSIONS We confirmed the association of a PNPLA3 variant with NAFLD in Hispanic Americans and African Americans, suggesting that PNPLA3 contributes to the variation in NAFLD across multiple ethnicities. This study adds to the growing evidence that some of the ethnic variation in NAFLD is genetic.
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Affiliation(s)
- Lynne E. Wagenknecht
- Division of Public Health Sciences, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA
| | - Nicholette D. Palmer
- Department of Biochemistry, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA
| | - Donald W. Bowden
- Department of Biochemistry, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA
| | - Jerome I. Rotter
- Cedars-Sinai Medical Center, Medical Genetics Institute, Los Angeles, CA, USA
| | - Jill M. Norris
- Department of Epidemiology, Colorado School of Public Health, Aurora, CO, USA
| | - Julie Ziegler
- Division of Public Health Sciences, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA
| | - Yii-Der I. Chen
- Cedars-Sinai Medical Center, Medical Genetics Institute, Los Angeles, CA, USA
| | - Steven Haffner
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Ann Scherzinger
- Bio-Imaging Research Laboratory, Department of Radiology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Carl D. Langefeld
- Division of Public Health Sciences, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA
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198
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Valenti L, Rumi M, Galmozzi E, Aghemo A, Del Menico B, De Nicola S, Dongiovanni P, Maggioni M, Fracanzani AL, Rametta R, Colombo M, Fargion S. Patatin-like phospholipase domain-containing 3 I148M polymorphism, steatosis, and liver damage in chronic hepatitis C. Hepatology 2011; 53:791-9. [PMID: 21319195 DOI: 10.1002/hep.24123] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Accepted: 11/18/2010] [Indexed: 12/12/2022]
Abstract
UNLABELLED Steatosis has been reported to negatively influence the natural history of chronic hepatitis C (CHC), but controversy remains over its causal role due to the confounding effect of adiposity, insulin resistance, and diabetes. The rs738409 C>G patatin-like phospholipase domain-containing 3 (PNPLA3) single nucleotide polymorphism (SNP), encoding for the I148M protein variant, influences liver fat without affecting insulin resistance and body composition. The aim of this study was to evaluate the effect of the rs738409 CG genotype on liver fat and fibrosis in CHC patients. We also explored the possible effect of PNPLA3 genotype on other steatosis-related complications, namely, treatment failure and hepatocellular carcinoma (HCC) development. To this end we considered two independent series of 325 and 494 CHC patients with available DNA and liver biopsy followed at tertiary referral centers in northern Italy. The rs738409 genotype was determined by a Taqman assay. The rs738409 GG genotype, observed in 10% of patients, was associated with steatosis independently of age, sex, body mass index (BMI), diabetes, alcohol intake, and viral genotype (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.4-2.7; P < 0.001). The association with rs738409 genotype was confirmed for severe steatosis, was independent of alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT) values, and was observed in all viral genotypes but the 3. The rs738409 GG genotype was associated with fibrosis stage and cirrhosis (OR 1.47, 95% CI 1.2-1.9; P = 0.002), treatment response (n = 470; OR 0.63, 95% CI 0.4-0.8; P = 0.006), and HCC occurrence (n = 325; OR 2.16, 95% CI 1.3-3.6; P = 0.002), independently of confounders. CONCLUSION The rs738409 PNPLA3 genotype influences steatosis development in CHC and is independently associated with cirrhosis and other steatosis-related clinical outcomes, such as lack of response to antiviral treatment and possibly HCC.
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Affiliation(s)
- Luca Valenti
- Department of Internal Medicine, Università degli Studi, Fondazione IRCCS Ospedale Maggiore Policlinico "Ca' Granda" IRCCS, Milan, Italy.
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199
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Kozlitina J, Boerwinkle E, Cohen JC, Hobbs HH. Dissociation between APOC3 variants, hepatic triglyceride content and insulin resistance. Hepatology 2011; 53:467-74. [PMID: 21274868 PMCID: PMC3057507 DOI: 10.1002/hep.24072] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 11/03/2010] [Indexed: 12/22/2022]
Abstract
UNLABELLED Nonalcoholic fatty liver disease (NAFLD) is an escalating health problem that is frequently associated with obesity and insulin resistance. The mechanistic relationship between NAFLD, obesity, and insulin resistance is not well understood. A nonsynonymous variant in patatin-like phospholipase domain containing 3 (rs738409, I148M) has been reproducibly associated with increased hepatic triglyceride content (HTGC) but has not been associated with either the body mass index (BMI) or indices of insulin resistance. Conversely, two sequence variants in apolipoprotein C3 (APOC3) that have been linked to hypertriglyceridemia (rs2854117 C > T and rs2854116 T > C) have recently been reported to be associated with both hepatic fat content and insulin resistance. Here we genotyped two APOC3 variants in 1228 African Americans, 843 European Americans and 426 Hispanics from a multiethnic population based study, the Dallas Heart Study and test for association with HTGC and homeostatic model of insulin resistance (HOMA-IR). We also examined the relationship between these two variants and HOMA-IR in the Atherosclerosis Risk in Communities (ARIC) study. No significant difference in hepatic fat content was found between carriers and noncarriers in the Dallas Heart Study. Neither APOC3 variant was associated with HOMA-IR in the Dallas Heart Study; this lack of association was confirmed in the ARIC study, even after the analysis was restricted to lean (BMI < 25 kg/m(2) ) individuals (n = 4399). CONCLUSION Our data do not support a causal relationship between these two variants in APOC3 and either HTGC or insulin resistance in middle-aged men and women.
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Affiliation(s)
- Julia Kozlitina
- McDermott Center for Human Growth and Development, University of Texas Southwestern Medical CenterDallas, TX
| | - Eric Boerwinkle
- Human Genetics Center and Institute for Molecular Medicine, University of Texas Health Science CenterHouston, TX
| | - Jonathan C Cohen
- McDermott Center for Human Growth and Development, University of Texas Southwestern Medical CenterDallas, TX
| | - Helen H Hobbs
- McDermott Center for Human Growth and Development, University of Texas Southwestern Medical CenterDallas, TX,Howard Hughes Medical Institute, University of Texas Southwestern Medical CenterDallas, TX
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200
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Basantani MK, Sitnick MT, Cai L, Brenner DS, Gardner NP, Li JZ, Schoiswohl G, Yang K, Kumari M, Gross RW, Zechner R, Kershaw EE. Pnpla3/Adiponutrin deficiency in mice does not contribute to fatty liver disease or metabolic syndrome. J Lipid Res 2011; 52:318-29. [PMID: 21068004 PMCID: PMC3023552 DOI: 10.1194/jlr.m011205] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 11/02/2010] [Indexed: 12/11/2022] Open
Abstract
PNPLA3 (adiponutrin, calcium-independent phospholipase A(2) epsilon [iPLA(2)ε]) is an adipose-enriched, nutritionally regulated protein that belongs to the patatin-like phospholipase domain containing (PNPLA) family of lipid metabolizing proteins. Genetic variations in the human PNPLA3 gene (i.e., the rs738409 I148M allele) has been strongly and repeatedly associated with fatty liver disease. Although human PNPLA3 has triacylglycerol (TAG) hydrolase and transacylase activities in vitro, its in vivo function and physiological relevance remain controversial. The objective of this study was to determine the metabolic consequences of global targeted deletion of the Pnpla3 gene in mice. We found that Pnpla3 mRNA expression is altered in adipose tissue and liver in response to acute and chronic nutritional challenges. However, global targeted deletion of the Pnpla3 gene in mice did not affect TAG hydrolysis, nor did it influence energy/glucose/lipid homoeostasis or hepatic steatosis/injury. Experimental interventions designed to increase Pnpla3 expression (refeeding, high-sucrose diet, diet-induced obesity, and liver X receptor agonism) likewise failed to reveal differences in the above-mentioned metabolic phenotypes. Expression of the Pnpla3 paralog, Pnpla5, was increased in adipose tissue but not in liver of Pnpla3-deficient mice, but compensatory regulation of genes involved in TAG metabolism was not identified. Together these data argue against a role for Pnpla3 loss-of-function in fatty liver disease or metabolic syndrome in mice.
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Affiliation(s)
- Mahesh K. Basantani
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Mitch T. Sitnick
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Lingzhi Cai
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Daniel S. Brenner
- Division of Endocrinology and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA
| | - Noah P. Gardner
- Division of Endocrinology and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA
| | - John Zhong Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX
| | | | - Kui Yang
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Manju Kumari
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Richard W. Gross
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Erin E. Kershaw
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
- Division of Endocrinology and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA
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