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Bo T, Gao L, Yao Z, Shao S, Wang X, Proud CG, Zhao J. Hepatic selective insulin resistance at the intersection of insulin signaling and metabolic dysfunction-associated steatotic liver disease. Cell Metab 2024; 36:947-968. [PMID: 38718757 DOI: 10.1016/j.cmet.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 01/22/2024] [Accepted: 04/09/2024] [Indexed: 06/26/2024]
Abstract
Insulin resistance (IR) is a major pathogenic factor in the progression of MASLD. In the liver, insulin suppresses gluconeogenesis and enhances de novo lipogenesis (DNL). During IR, there is a defect in insulin-mediated suppression of gluconeogenesis, but an unrestrained increase in hepatic lipogenesis persists. The mechanism of increased hepatic steatosis in IR is unclear and remains controversial. The key discrepancy is whether insulin retains its ability to directly regulate hepatic lipogenesis. Blocking insulin/IRS/AKT signaling reduces liver lipid deposition in IR, suggesting insulin can still regulate lipid metabolism; hepatic glucose metabolism that bypasses insulin's action may contribute to lipogenesis; and due to peripheral IR, other tissues are likely to impact liver lipid deposition. We here review the current understanding of insulin's action in governing different aspects of hepatic lipid metabolism under normal and IR states, with the purpose of highlighting the essential issues that remain unsettled.
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Affiliation(s)
- Tao Bo
- Key Laboratory of Endocrine Glucose & Lipids Metabolism and Brain Aging, Ministry of Education, Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Ling Gao
- Key Laboratory of Endocrine Glucose & Lipids Metabolism and Brain Aging, Ministry of Education, Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong, China
| | - Zhenyu Yao
- Key Laboratory of Endocrine Glucose & Lipids Metabolism and Brain Aging, Ministry of Education, Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong, China
| | - Shanshan Shao
- Key Laboratory of Endocrine Glucose & Lipids Metabolism and Brain Aging, Ministry of Education, Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong, China
| | - Xuemin Wang
- Lifelong Health, South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA, Australia
| | - Christopher G Proud
- Lifelong Health, South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA, Australia.
| | - Jiajun Zhao
- Key Laboratory of Endocrine Glucose & Lipids Metabolism and Brain Aging, Ministry of Education, Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China; Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong, China.
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2
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Wang S, Zhou Y, Yu R, Ling J, Li B, Yang C, Cheng Z, Qian R, Lin Z, Yu C, Zheng J, Zheng X, Jia Q, Wu W, Wu Q, Chen M, Yuan S, Dong W, Shi Y, Jansen R, Yang C, Hao Y, Yao M, Qin W, Jin H. Loss of hepatic FTCD promotes lipid accumulation and hepatocarcinogenesis by upregulating PPARγ and SREBP2. JHEP Rep 2023; 5:100843. [PMID: 37675273 PMCID: PMC10477690 DOI: 10.1016/j.jhepr.2023.100843] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 06/02/2023] [Accepted: 06/26/2023] [Indexed: 09/08/2023] Open
Abstract
Background & Aims Exploiting key regulators responsible for hepatocarcinogenesis is of great importance for the prevention and treatment of hepatocellular carcinoma (HCC). However, the key players contributing to hepatocarcinogenesis remain poorly understood. We explored the molecular mechanisms underlying the carcinogenesis and progression of HCC for the development of potential new therapeutic targets. Methods The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) and Genotype-Tissue Expression (GTEx) databases were used to identify genes with enhanced expression in the liver associated with HCC progression. A murine liver-specific Ftcd knockout (Ftcd-LKO) model was generated to investigate the role of formimidoyltransferase cyclodeaminase (FTCD) in HCC. Multi-omics analysis of transcriptomics, metabolomics, and proteomics data were applied to further analyse the molecular effects of FTCD expression on hepatocarcinogenesis. Functional and biochemical studies were performed to determine the significance of loss of FTCD expression and the therapeutic potential of Akt inhibitors in FTCD-deficient cancer cells. Results FTCD is highly expressed in the liver but significantly downregulated in HCC. Patients with HCC and low levels of FTCD exhibited worse prognosis, and patients with liver cirrhosis and low FTCD levels exhibited a notable higher probability of developing HCC. Hepatocyte-specific knockout of FTCD promoted both chronic diethylnitrosamine-induced and spontaneous hepatocarcinogenesis in mice. Multi-omics analysis showed that loss of FTCD affected fatty acid and cholesterol metabolism in hepatocarcinogenesis. Mechanistically, loss of FTCD upregulated peroxisome proliferator-activated receptor (PPAR)γ and sterol regulatory element-binding protein 2 (SREBP2) by regulating the PTEN/Akt/mTOR signalling axis, leading to lipid accumulation and hepatocarcinogenesis. Conclusions Taken together, we identified a FTCD-regulated lipid metabolic mechanism involving PPARγ and SREBP2 signaling in hepatocarcinogenesis and provide a rationale for therapeutically targeting of HCC driven by downregulation of FTCD. Impact and implications Exploiting key molecules responsible for hepatocarcinogenesis is significant for the prevention and treatment of HCC. Herein, we identified formimidoyltransferase cyclodeaminase (FTCD) as the top enhanced gene, which could serve as a predictive and prognostic marker for patients with HCC. We generated and characterised the first Ftcd liver-specific knockout murine model. We found loss of FTCD expression upregulated peroxisome proliferator-activated receptor (PPAR)γ and sterol regulatory element-binding protein 2 (SREBP2) by regulating the PTEN/Akt/mTOR signalling axis, leading to lipid accumulation and hepatocarcinogenesis, and provided a rationale for therapeutic targeting of HCC driven by downregulation of FTCD.
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Affiliation(s)
- Siying Wang
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yangyang Zhou
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ruobing Yu
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing Ling
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Botai Li
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Yang
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhuoan Cheng
- Department of Liver Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ruolan Qian
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhang Lin
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chengtao Yu
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jiaojiao Zheng
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xingling Zheng
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qi Jia
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wei Wu
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiangxin Wu
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mengnuo Chen
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shengxian Yuan
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Wei Dong
- Department of Pathology, Eastern Hepatobiliary Surgery Hospital, The Second Military Medical University, Shanghai, China
| | - Yaoping Shi
- Department of Interventional Oncology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Robin Jansen
- Division of Molecular Carcinogenesis, Oncode Institute, Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Chen Yang
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- State Key Laboratory of Translational Medicine and Innovative Drug Development, Jiangsu Simcere Pharmaceutical Co. Ltd., Nanjing, China
| | - Yujun Hao
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ming Yao
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenxin Qin
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Haojie Jin
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Koo SY, Park EJ, Noh HJ, Jo SM, Ko BK, Shin HJ, Lee CW. Ubiquitination Links DNA Damage and Repair Signaling to Cancer Metabolism. Int J Mol Sci 2023; 24:ijms24098441. [PMID: 37176148 PMCID: PMC10179089 DOI: 10.3390/ijms24098441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 05/15/2023] Open
Abstract
Changes in the DNA damage response (DDR) and cellular metabolism are two important factors that allow cancer cells to proliferate. DDR is a set of events in which DNA damage is recognized, DNA repair factors are recruited to the site of damage, the lesion is repaired, and cellular responses associated with the damage are processed. In cancer, DDR is commonly dysregulated, and the enzymes associated with DDR are prone to changes in ubiquitination. Additionally, cellular metabolism, especially glycolysis, is upregulated in cancer cells, and enzymes in this metabolic pathway are modulated by ubiquitination. The ubiquitin-proteasome system (UPS), particularly E3 ligases, act as a bridge between cellular metabolism and DDR since they regulate the enzymes associated with the two processes. Hence, the E3 ligases with high substrate specificity are considered potential therapeutic targets for treating cancer. A number of small molecule inhibitors designed to target different components of the UPS have been developed, and several have been tested in clinical trials for human use. In this review, we discuss the role of ubiquitination on overall cellular metabolism and DDR and confirm the link between them through the E3 ligases NEDD4, APC/CCDH1, FBXW7, and Pellino1. In addition, we present an overview of the clinically important small molecule inhibitors and implications for their practical use.
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Affiliation(s)
- Seo-Young Koo
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Eun-Ji Park
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Hyun-Ji Noh
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Su-Mi Jo
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Bo-Kyoung Ko
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Hyun-Jin Shin
- Team of Radiation Convergence Research, Korea Institute of Radiological & Medical Sciences, Seoul 01812, Republic of Korea
| | - Chang-Woo Lee
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
- SKKU Institute for Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
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4
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Liu Y, Zhang P, Li J, Li H, Zhou C, Zhang Y, Ming Y. Association between serum lipid profile and liver fibrosis in patients infected with Schistosoma japonicum. Parasit Vectors 2022; 15:268. [PMID: 35906693 PMCID: PMC9336000 DOI: 10.1186/s13071-022-05359-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 06/10/2022] [Indexed: 12/15/2022] Open
Abstract
Background Liver fibrosis is thought to have a close relationship with lipid profile. The possible association between lipids and liver fibrosis of different etiologies has been widely explored. However, the association between lipids and liver fibrosis in patients infected with Schistosoma japonicum remains unclear. In the present study we undertook a preliminary exploration of the association between lipid profile and liver fibrosis, and developed a new predictive index for liver fibrosis in S. japonicum-infected patients. Methods A total of 1503 patients diagnosed with S. japonicum at Xiangyue Hospital, China were enrolled in this retrospective study. The patients were divided into two groups, i.e., those with and those without liver fibrosis, by two experienced schistosomiasis specialists, according to the results of liver ultrasound examination. Demographic, clinical, and laboratory data were collected. Multivariable logistic models were used to estimate the independent associations between lipid profile and liver fibrosis. Receiver operating characteristic (ROC) curves were used to assess the discriminative ability of the new index in predicting liver fibrosis in patients with schistosomiasis. Results Logistic regression analysis showed that high-density lipoprotein (HDL) [adjusted odds ratio (aOR), 95% confidence interval (CI) 7.334, 5.051–10.649; P < 0.001], low-density lipoprotein (LDL) (aOR, 95% CI 0.434, 0.370–0.509; P < 0.001), hemoglobin (HB) (aOR, 95% CI 0.979, 0.971–0.987; P < 0.001) and platelets (PLT) (aOR, 95% CI 0.996, 0.994–0.999; P < 0.001) were independently associated with liver fibrosis in patients with schistosomiasis. ROC analysis indicated that the combination of HDL, LDL and HB levels [(HDL × 100)/(LDL × HB)] had a higher area under the ROC curve (AUC = 0.773), and thus may better predict liver fibrosis than the aspartate transaminase-to-platelet ratio index (AUC = 0.608) and fibrosis index based on four factors (AUC = 0.624). Conclusions To the best of our knowledge, this is the first study to report that HDL, LDL, HB and PLT levels are independently associated with liver fibrosis in patients with schistosomiasis. (HDL × 100)/(LDL × HB) outperformed the aspartate transaminase-to-platelet ratio index and fibrosis index based on four factors in terms of ROC, and thus could be a new predictive index for liver fibrosis. These findings may help clinicians to more easily and effectively diagnose liver fibrosis in patients with schistosomiasis. Graphical abstract ![]()
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Affiliation(s)
- Yang Liu
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China
| | - PengPeng Zhang
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China.,Engineering and Technology Research Center for Transplantation Medicine, National Health Commission, Changsha, 410013, China
| | - JunHui Li
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China.,Engineering and Technology Research Center for Transplantation Medicine, National Health Commission, Changsha, 410013, China
| | - Hao Li
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China
| | - Chen Zhou
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China
| | - Yu Zhang
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China
| | - YingZi Ming
- Transplantation Center, Third Xiangya Hospital, Central South University, Changsha, China. .,Engineering and Technology Research Center for Transplantation Medicine, National Health Commission, Changsha, 410013, China.
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5
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Kaymakcalan H, Kaya İ, Cevher Binici N, Nikerel E, Özbaran B, Görkem Aksoy M, Erbilgin S, Özyurt G, Jahan N, Çelik D, Yararbaş K, Yalçınkaya L, Köse S, Durak S, Ercan-Sencicek AG. Prevalence and clinical/molecular characteristics of PTEN mutations in Turkish children with autism spectrum disorders and macrocephaly. Mol Genet Genomic Med 2021; 9:e1739. [PMID: 34268892 PMCID: PMC8404225 DOI: 10.1002/mgg3.1739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/15/2021] [Indexed: 12/25/2022] Open
Abstract
Background Phosphatase and tensin homolog (PTEN) germline mutations are associated with cancer syndromes (PTEN hamartoma tumor syndrome; PHTS) and in pediatric patients with autism spectrum disorder (ASD) and macrocephaly. The exact prevalence of PTEN mutations in patients with ASD and macrocephaly is uncertain; with prevalence rates ranging from 1% to 17%. Most studies are retrospective and contain more adult than pediatric patients, there is a need for more prospective pediatric studies. Methods We recruited 131 patients (108 males, 23 females) with ASD and macrocephaly between the ages of 3 and 18 from five child and adolescent psychiatry clinics in Turkey from July 2018 to December 2019. We defined macrocephaly as occipito‐frontal HC size at or greater than 2 standard deviations (SD) above the mean for age and sex on standard growth charts. PTEN gene sequence analysis was performed using a MiSeq next generation sequencing (NGS) platform, (Illumina). Conclusion PTEN gene sequence analyses identified three pathogenic/likely pathogenic mutations [NM_000314.6; p.(Pro204Leu), (p.Arg233*) and novel (p.Tyr176Cys*8)] and two variants of uncertain significance (VUS) [NM_000314.6; p.(Ala79Thr) and c.*10del]. We also report that patient with (p.Tyr176Cys*8) mutation has Grade 1 hepatosteatosis, a phenotype not previously described. This is the first PTEN prevalence study of patients with ASD and macrocephaly in Turkey and South Eastern Europe region with a largest homogenous cohort. The prevalence of PTEN mutations was found 3.8% (VUS included) or 2.29% (VUS omitted). We recommend testing for PTEN mutations in all patients with ASD and macrocephaly.
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Affiliation(s)
- Hande Kaymakcalan
- Pediatric Genetics Unit, Department of Pediatrics, Demiroglu Bilim University, Istanbul, Turkey
| | - İlyas Kaya
- Department of Child and Adolescent Psychiatry, Istanbul University Istanbul Faculty of Medicine, Istanbul, Turkey
| | - Nagihan Cevher Binici
- Department of Child and Adolescent Psychiatry, Dr Behcet Uz Child Disease and Surgery Training and Research Hospital, Istanbul, Turkey
| | - Emrah Nikerel
- Department of Bioinformatics, Yeditepe University, Istanbul, Turkey
| | - Burcu Özbaran
- Department of Child and Adolescent Psychiatry, Ege University Faculty of Medicine, Izmir, Turkey
| | - Mehmet Görkem Aksoy
- Department of Child and Adolescent Psychiatry, Ege University Faculty of Medicine, Izmir, Turkey
| | - Seda Erbilgin
- Department of Child and Adolescent Psychiatry, Prof. Dr. Cemil Tascioglu City Hospital, Istanbul, Turkey
| | - Gonca Özyurt
- Department of Child and Adolescent Psychiatry, Izmir Katip Celebi University Faculty of Medicine, Izmir, Turkey
| | - Noor Jahan
- Department of Child and Adolescent Psychiatry, Ege University Faculty of Medicine, Izmir, Turkey
| | - Didem Çelik
- Department of Child and Adolescent Psychiatry, Ege University Faculty of Medicine, Izmir, Turkey
| | - Kanay Yararbaş
- Department of Medical Genetics, Demiroglu Bilim University, Istanbul, Turkey
| | - Leyla Yalçınkaya
- Department of Molecular Biology and Genetics, Bilkent University Faculty of Science, Ankara, Turkey
| | - Sezen Köse
- Department of Child and Adolescent Psychiatry, Ege University Faculty of Medicine, Izmir, Turkey
| | - Sibel Durak
- Department of Child and Adolescent Psychiatry, Dr Behcet Uz Child Disease and Surgery Training and Research Hospital, Istanbul, Turkey
| | - Adife Gulhan Ercan-Sencicek
- Masonic Medical Research Institute, Utica, New York, USA.,Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Neurosurgery, Program on Neurogenetics, New Haven, Connecticut, USA
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6
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Yao DW, Ma J, Yang CL, Chen LL, He QY, Coleman DN, Wang TZ, Jiang XL, Luo J, Ma Y, Loor JJ. Phosphatase and tensin homolog (PTEN) suppresses triacylglycerol accumulation and monounsaturated fatty acid synthesis in goat mammary epithelial cells. J Dairy Sci 2021; 104:7283-7294. [PMID: 33741170 DOI: 10.3168/jds.2020-18784] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 02/04/2021] [Indexed: 12/30/2022]
Abstract
Phosphatase and tensin homolog (PTEN) is a well-known tumor suppressor in nonruminants and regulates various cellular processes including growth through dephosphorylation of phosphoinositide substrates. Although studies with bovine mammary tissue suggested a role for PTEN during lactation, its potential role in lipid metabolism remains unknown. Objectives of the present study were to determine PTEN abundance in goat mammary tissue at 2 stages of lactation (n = 6 Xinong Saanen dairy goats per stage), and to use gene-silencing and adenoviral transfections in vitro with isolated goat mammary epithelial cells (GMEC) to evaluate the role of PTEN abundance of lipid metabolism-related genes. Abundance of PTEN decreased by 51.5% at peak lactation compared with the dry period. The PTEN was overexpressed in isolated GMEC through adenoviral transfection using an adenovirus system with Ad-GFP (recombinant adenovirus of green fluorescent protein) as control, and silenced via targeted small interfering RNA (siRNA) transfection with a scrambled small interfering RNA as a negative control. Cell culture was performed for 48 h before RNA extraction, triacylglycerol (TAG) analysis, and fatty acid analysis. Overexpression of PTEN downregulated abundance of acetyl-coenzyme A carboxylase α (ACACA), fatty acid synthase (FASN), sterol regulatory element binding transcription factor1 (SREBF1), stearoyl-coenzyme A desaturase 1 (SCD1), diacylglycerol acytransferase 1 (DGAT1), 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT6) coupled with an increase in patatin-like-phospholipase domain containing 2 (PNPLA2), hormone-sensitive lipase (LIPE), and carnitine palmitoyltransferase 1 β (CPT1B). Furthermore, overexpressing PTEN in vitro resulted in a significant decrease in TAG concentration and concentration of C16:1. In contrast, interference of PTEN led to an opposite effect on lipid metabolism in GMEC. These changes suggested a shift from lipogenesis and esterification to lipolysis and fatty acid oxidation. Collectively, PTEN seems to play a role in monounsaturated fatty acids synthesis and lipid accumulation in GMEC.
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Affiliation(s)
- D W Yao
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381
| | - J Ma
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381
| | - C L Yang
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381
| | - L L Chen
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381
| | - Q Y He
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - D N Coleman
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801
| | - T Z Wang
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381
| | - X L Jiang
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381
| | - J Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - Y Ma
- Tianjin Institute of Animal Husbandry and Veterinary Medicine, Tianjin Academy of Agricultural Sciences, Tianjin, P. R. China 300381.
| | - J J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
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7
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Yang X, Ding W, Qian X, Jiang P, Chen Q, Zhang X, Lu Y, Wu J, Sun F, Pan Z, Li X, Pan W. Schistosoma japonicum Infection Leads to the Reprogramming of Glucose and Lipid Metabolism in the Colon of Mice. Front Vet Sci 2021; 8:645807. [PMID: 33791356 PMCID: PMC8006365 DOI: 10.3389/fvets.2021.645807] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 02/17/2021] [Indexed: 01/21/2023] Open
Abstract
The deposition of Schistosoma japonicum (S. japonicum) eggs commonly induces inflammation, fibrosis, hyperplasia, ulceration, and polyposis in the colon, which poses a serious threat to human health. However, the underlying mechanism is largely neglected. Recently, the disorder of glucose and lipid metabolism was reported to participate in the liver fibrosis induced by the parasite, which provides a novel clue for studying the underlying mechanism of the intestinal pathology of the disease. This study focused on the metabolic reprogramming profiles of glucose and lipid in the colon of mice infected by S. japonicum. We found that S. japonicum infection shortened the colonic length, impaired intestinal integrity, induced egg-granuloma formation, and increased colonic inflammation. The expression of key enzymes involved in the pathways regulating glucose and lipid metabolism was upregulated in the colon of infected mice. Conversely, phosphatase and tensin homolog deleted on chromosome ten (PTEN) and its downstream signaling targets were significantly inhibited after infection. In line with these results, in vitro stimulation with soluble egg antigens (SEA) downregulated the expression of PTEN in CT-26 cells and induced metabolic alterations similar to that observed under in vivo results. Moreover, PTEN over-expression prevented the reprogramming of glucose and lipid metabolism induced by SEA in CT-26 cells. Overall, the present study showed that S. japonicum infection induces the reprogramming of glucose and lipid metabolism in the colon of mice, and PTEN may play a vital role in mediating this metabolic reprogramming. These findings provide a novel insight into the pathogenicity of S. japonicum in hosts.
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Affiliation(s)
- Xiaoying Yang
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China
| | - Weimin Ding
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China.,School of Life Sciences, Xuzhou Medical University, Xuzhou, China
| | - Xinyu Qian
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China.,The First Clinical Medical College, Xuzhou Medical University, Xuzhou, China
| | - Pengfei Jiang
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China
| | - Qingqing Chen
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China.,The First Clinical Medical College, Xuzhou Medical University, Xuzhou, China
| | - Xin Zhang
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China.,The First Clinical Medical College, Xuzhou Medical University, Xuzhou, China
| | - Yang Lu
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China.,The First Clinical Medical College, Xuzhou Medical University, Xuzhou, China
| | - Jiacheng Wu
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China.,The Second Clinical Medical College, Xuzhou Medical University, Xuzhou, China
| | - Fenfen Sun
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China
| | - Zhihua Pan
- National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China
| | - Xiangyang Li
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China
| | - Wei Pan
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,National Experimental Teaching Demonstration Center of Basic Medicine, Xuzhou Medical University, Xuzhou, China
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8
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Tian M, Wang J, Liu S, Li X, Li J, Yang J, Zhang C, Zhang W. Hepatic HuR protects against the pathogenesis of non-alcoholic fatty liver disease by targeting PTEN. Cell Death Dis 2021; 12:236. [PMID: 33664225 PMCID: PMC7933173 DOI: 10.1038/s41419-021-03514-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 02/01/2021] [Accepted: 02/05/2021] [Indexed: 12/22/2022]
Abstract
The liver plays an important role in lipid and glucose metabolism. Here, we show the role of human antigen R (HuR), an RNA regulator protein, in hepatocyte steatosis and glucose metabolism. We investigated the level of HuR in the liver of mice fed a normal chow diet (NCD) and a high-fat diet (HFD). HuR was downregulated in the livers of HFD-fed mice. Liver-specific HuR knockout (HuRLKO) mice showed exacerbated HFD-induced hepatic steatosis along with enhanced glucose tolerance as compared with control mice. Mechanistically, HuR could bind to the adenylate uridylate-rich elements of phosphatase and tensin homolog deleted on the chromosome 10 (PTEN) mRNA 3' untranslated region, resulting in the increased stability of Pten mRNA; genetic knockdown of HuR decreased the expression of PTEN. Finally, lentiviral overexpression of PTEN alleviated the development of hepatic steatosis in HuRLKO mice in vivo. Overall, HuR regulates lipid and glucose metabolism by targeting PTEN.
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Affiliation(s)
- Mi Tian
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Cardiovascular Disease Research Center of Shandong First Medical University, Central Hospital Affiliated to Shandong First Medical University, Shandong, China
| | - Jingjing Wang
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Shandong University, Shandong, China
| | - Shangming Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Shandong University, Shandong, China
| | - Xinyun Li
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Jingyuan Li
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Jianmin Yang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Cheng Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Wencheng Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
- Cardiovascular Disease Research Center of Shandong First Medical University, Central Hospital Affiliated to Shandong First Medical University, Shandong, China.
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9
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Zhao B, Luo C, Zhang M, Xing F, Luo S, Fu S, Sun X. Knockdown of phosphatase and tensin homolog (PTEN) inhibits fatty acid oxidation and reduces very low density lipoprotein assembly and secretion in calf hepatocytes. J Dairy Sci 2020; 103:10728-10741. [PMID: 32952018 DOI: 10.3168/jds.2019-17920] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 07/08/2020] [Indexed: 12/30/2022]
Abstract
Dairy cows with fatty liver exhibit hepatic lipid accumulation and disturbances in fatty acid oxidation and lipid transport. Phosphatase and tensin homolog (PTEN), a lipid phosphatase, regulates intrahepatic fatty acid oxidation and lipid transport in mice. Whether PTEN play a role in fatty acid oxidation and very low density lipoprotein (VLDL) assembly in calf hepatocytes are unknown. Hepatocytes isolated from 3 healthy female Holstein calves (1 d old, 30-40 kg) were infected with empty adenovirus with green fluorescent protein for 48 h (Ad-GFP group) or infected with PTEN knockdown adenovirus for 48 h (Ad-shPTEN group), or cultured in RPMI-1640 without Ad-shPTEN or Ad-GFP (control group). Compared with the Ad-GFP group, PTEN knockdown decreased mRNA and protein abundance and the activity of fatty acid oxidation-related molecules, including acyl-coA synthetase long-chain 1, carnitine palmitoyltransferase 1, carnitine palmitoyltransferase 2, and 3-hydroxy acyl-coA dehydrogenase. Furthermore, PTEN knockdown decreased mRNA and protein abundance of VLDL assembly-related molecules, including apolipoprotein B100, apolipoprotein E, microsomal triglyceride transfer protein, and low density lipoprotein receptor. Importantly, PTEN knockdown promoted triglyceride accumulation in hepatocytes and reduced the VLDL content in culture medium. A subsequent study was conducted on the following 4 groups: cells infected with Ad-GFP for 48 h and then treated with 2% BSA for another 24 h (Ad-GFP + BSA); cells infected with Ad-GFP for 48 h and then treated with 1.2 mM free fatty acids (FFA) and 2% BSA for another 24 h (Ad-GFP + 1.2 mM FFA); cells infected with Ad-shPTEN for 48 h and then treated with 2% BSA for another 24 h (Ad-shPTEN + BSA); cells infected with Ad-shPTEN for 48 h and then treated with 1.2 mM FFA and 2% BSA for another 24 h (Ad-shPTEN + 1.2 mM FFA). Compared with Ad-GFP + BSA, the abundances of PTEN and of fatty acid oxidation- and VLDL assembly-related proteins were lower in the Ad-GFP + 1.2 mM FFA group. Importantly, PTEN knockdown heightened the increase in triglyceride accumulation of hepatocytes and the decrease in VLDL content in culture medium induced by FFA. Overall, these in vitro data indicate that FFA inhibits PTEN expression, leading to triglyceride accumulation and the inhibition of VLDL assembly in calf hepatocytes. These findings suggest that PTEN may be a potential therapeutic target for FFA-induced hepatic steatosis in dairy cows.
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Affiliation(s)
- Bichen Zhao
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China
| | - Chunhai Luo
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China
| | - Menglong Zhang
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China
| | - Feifei Xing
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China
| | - Shengbin Luo
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China
| | - Shixin Fu
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China.
| | - Xudong Sun
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, Heilongjiang Province 163319, China.
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10
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Ikeda Y, Murakami M, Nakagawa Y, Tsuji A, Kitagishi Y, Matsuda S. Diet induces hepatocyte protection in fatty liver disease via modulation of PTEN signaling. Biomed Rep 2020; 12:295-302. [PMID: 32382414 PMCID: PMC7201141 DOI: 10.3892/br.2020.1299] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 07/11/2019] [Indexed: 02/07/2023] Open
Abstract
Fatty liver disease (FLD) is characterized by accumulation of excess fat in the liver. The underlying molecular mechanism associated with the progression of the disease has been in elusive. Hepatocellular demise due to increased oxidative stress resulting in an inflammatory response may be a key feature in FLD. Recent advances in molecular biology have led to an improved understanding of the molecular pathogenesis, suggesting a critical association between the PI3K/AKT/PTEN signaling pathway and FLD. In particular, PTEN has been associated with regulating the pathogenesis of hepatocyte degeneration. Given the function of mitochondria in reactive oxygen species (ROS) generation and the initiation of oxidative stress, the mitochondrial antioxidant network is of interest. It is vital to balance the activity of intracellular key molecules to maintain a healthy liver. Consequently, onset of FLD may be delayed using dietary protective agents that alter PTEN signaling and reduce ROS levels. The advancement of research on dietary regulation with a focus on modulatory roles in ROS generation and PTEN associated signaling is summarized in the current study, supporting further preventive and therapeutic exploration.
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Affiliation(s)
- Yuka Ikeda
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Mutsumi Murakami
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Yukie Nakagawa
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Ai Tsuji
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Yasuko Kitagishi
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Satoru Matsuda
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
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11
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Zhang J, Jazii FR, Haghighi MM, Alvares D, Liu L, Khosraviani N, Adeli K. miR-130b is a potent stimulator of hepatic very-low-density lipoprotein assembly and secretion via marked induction of microsomal triglyceride transfer protein. Am J Physiol Endocrinol Metab 2020; 318:E262-E275. [PMID: 31821038 DOI: 10.1152/ajpendo.00276.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
miR-130b is a microRNA whose expression is particularly elevated within adipose tissue and in the circulation in diabetic states. Hepatic miR-130b expression has been linked to hepatocellular carcinoma and changes in lipid metabolism. Here, we investigated the role of miR-130b in hepatic lipid homeostasis and lipoprotein export. We observed that overexpression of miR-130b-3p or -5p in HepG2 cells markedly enhanced the secretion of very-low-density lipoprotein (VLDL) particles, enhanced the secretion of [3H]glycerol metabolically labeled triglyceride (TG), and significantly increased the number or the average size of lipid droplets (LDs), respectively. Overexpression of miR-130b also altered the expression of key genes involved in lipid metabolism and in particular markedly increased both mRNA and protein expression levels of microsomal triglyceride transfer protein (MTP). Conversely, the miR-130b inhibitor decreased mRNA levels of MTP and fatty acid synthase (FAS) in HepG2 cells. However, dual-luciferase reporter assays indicated that MTP is not a direct target of miR-130b-3p. miR-130b overexpression did not alter de novo synthesized TG or the stability and secretion of apolipoprotein B 100. Interestingly, knockdown of phosphatase and tensin homolog (PTEN) blocked the upregulation of MTP mRNA induced by miR-130b. Finally, miR-130b-induced stimulation of VLDL secretion was also observed in a second hepatocyte cell culture model, immortalized human hepatocytes, confirming the effects observed in HepG2 cells. Overall, these data suggest a potential role for miR-130b in promoting hepatic VLDL assembly and secretion mediated by marked stimulation of MTP expression and TG mobilization. Thus miR-130b overexpression corrects the defect in VLDL production in HepG2 cells.
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Affiliation(s)
- Jing Zhang
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Ferdous Rastgar Jazii
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Mahdi Montazer Haghighi
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Danielle Alvares
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Lipei Liu
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Negar Khosraviani
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Khosrow Adeli
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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12
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Qian XY, Ding WM, Chen QQ, Zhang X, Jiang WQ, Sun FF, Li XY, Yang XY, Pan W. The Metabolic Reprogramming Profiles in the Liver Fibrosis of Mice Infected with Schistosoma japonicum. Inflammation 2020; 43:731-743. [DOI: 10.1007/s10753-019-01160-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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13
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Iqbal J, Jahangir Z, Al-Qarni AA. Microsomal Triglyceride Transfer Protein: From Lipid Metabolism to Metabolic Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1276:37-52. [DOI: 10.1007/978-981-15-6082-8_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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14
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Zhu M, Lu T, Jia Y, Luo X, Gopal P, Li L, Odewole M, Renteria V, Singal AG, Jang Y, Ge K, Wang SC, Sorouri M, Parekh JR, MacConmara MP, Yopp AC, Wang T, Zhu H. Somatic Mutations Increase Hepatic Clonal Fitness and Regeneration in Chronic Liver Disease. Cell 2019; 177:608-621.e12. [PMID: 30955891 PMCID: PMC6519461 DOI: 10.1016/j.cell.2019.03.026] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/20/2019] [Accepted: 03/11/2019] [Indexed: 12/19/2022]
Abstract
Normal tissues accumulate genetic changes with age, but it is unknown if somatic mutations promote clonal expansion of non-malignant cells in the setting of chronic degenerative diseases. Exome sequencing of diseased liver samples from 82 patients revealed a complex mutational landscape in cirrhosis. Additional ultra-deep sequencing identified recurrent mutations in PKD1, PPARGC1B, KMT2D, and ARID1A. The number and size of mutant clones increased as a function of fibrosis stage and tissue damage. To interrogate the functional impact of mutated genes, a pooled in vivo CRISPR screening approach was established. In agreement with sequencing results, examination of 147 genes again revealed that loss of Pkd1, Kmt2d, and Arid1a promoted clonal expansion. Conditional heterozygous deletion of these genes in mice was also hepatoprotective in injury assays. Pre-malignant somatic alterations are often viewed through the lens of cancer, but we show that mutations can promote regeneration, likely independent of carcinogenesis.
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Affiliation(s)
- Min Zhu
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tianshi Lu
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Quantitative Biomedical Research Center, Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA, 75390
| | - Yuemeng Jia
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xin Luo
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Purva Gopal
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lin Li
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mobolaji Odewole
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Veronica Renteria
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Amit G Singal
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Kai Ge
- NIDDK, NIH, Bethesda, MD 20892, USA
| | - Sam C Wang
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mahsa Sorouri
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Justin R Parekh
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Malcolm P MacConmara
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Adam C Yopp
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tao Wang
- Quantitative Biomedical Research Center, Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA, 75390; Kidney Cancer Program, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA, 75390.
| | - Hao Zhu
- Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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15
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Lee G, Jeong YS, Kim DW, Kwak MJ, Koh J, Joo EW, Lee JS, Kah S, Sim YE, Yim SY. Clinical significance of APOB inactivation in hepatocellular carcinoma. Exp Mol Med 2018; 50:1-12. [PMID: 30429453 PMCID: PMC6235894 DOI: 10.1038/s12276-018-0174-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 07/03/2018] [Accepted: 07/18/2018] [Indexed: 12/19/2022] Open
Abstract
Recent findings from The Cancer Genome Atlas project have provided a comprehensive map of genomic alterations that occur in hepatocellular carcinoma (HCC), including unexpected mutations in apolipoprotein B (APOB). We aimed to determine the clinical significance of this non-oncogenetic mutation in HCC. An Apob gene signature was derived from genes that differed between control mice and mice treated with siRNA specific for Apob (1.5-fold difference; P < 0.005). Human gene expression data were collected from four independent HCC cohorts (n = 941). A prediction model was constructed using Bayesian compound covariate prediction, and the robustness of the APOB gene signature was validated in HCC cohorts. The correlation of the APOB signature with previously validated gene signatures was performed, and network analysis was conducted using ingenuity pathway analysis. APOB inactivation was associated with poor prognosis when the APOB gene signature was applied in all human HCC cohorts. Poor prognosis with APOB inactivation was consistently observed through cross-validation with previously reported gene signatures (NCIP A, HS, high-recurrence SNUR, and high RS subtypes). Knowledge-based gene network analysis using genes that differed between low-APOB and high-APOB groups in all four cohorts revealed that low-APOB activity was associated with upregulation of oncogenic and metastatic regulators, such as HGF, MTIF, ERBB2, FOXM1, and CD44, and inhibition of tumor suppressors, such as TP53 and PTEN. In conclusion, APOB inactivation is associated with poor outcome in patients with HCC, and APOB may play a role in regulating multiple genes involved in HCC development.
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Affiliation(s)
- Gena Lee
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Yun Seong Jeong
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Do Won Kim
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Min Jun Kwak
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jiwon Koh
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
| | - Eun Wook Joo
- Department of Gynecology, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Ju-Seog Lee
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Susie Kah
- Department of Internal Medicine, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Yeong-Eun Sim
- Department of Internal Medicine, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Sun Young Yim
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. .,Department of Internal Medicine, Korea University, College of Medicine, Seoul, Korea.
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16
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Wang H, Feng Z, Xie J, Wen F, Jv M, Liang T, Li J, Wang Y, Zuo Y, Li S, Li R, Li Z, Zhang B, Liang X, Liu S, Shi W, Wang W. Podocyte-specific knockin of PTEN protects kidney from hyperglycemia. Am J Physiol Renal Physiol 2018; 314:F1096-F1107. [PMID: 29361670 DOI: 10.1152/ajprenal.00575.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has proven to be downregulated in podocytes challenged with high glucose (HG), and knockout of PTEN in podocytes aggravated the progression of diabetic kidney disease (DKD). However, whether podocyte-specific knockin of PTEN protects the kidney against hyperglycemia in vivo remains unknown. The inducible podocyte-specific PTEN knockin (PPKI) mice were generated by crossing newly created transgenic loxP-stop- loxP-PTEN mice with podocin-iCreERT2 mice. Diabetes mellitus was induced in mice by intraperitoneal injection of streptozotocin at a dose of 150 mg/kg. In vitro, small interfering RNA and adenovirus interference were used to observe the role of PTEN in HG-treated podocytes. Our data demonstrated that PTEN was markedly reduced in the podocytes of patients with DKD and focal segmental glomerulosclerosis, as well as in those of db/db mice. Interestingly, podocyte-specific knockin of PTEN significantly alleviated albuminuria, mesangial matrix expansion, effacement of podocyte foot processes, and incrassation of glomerular basement membrane in diabetic PPKI mice compared with wild-type diabetic mice, whereas no alteration was observed in the level of blood glucose. The potential renal protection of overexpressed PTEN in podocytes was partly attributed with an improvement in autophagy and motility and the inhibition of apoptosis. Our results showed that podocyte-specific knockin of PTEN protected the kidney against hyperglycemia in vivo , suggesting that targeting PTEN might be a novel and promising therapeutic strategy against DKD.
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Affiliation(s)
- Huizhen Wang
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Ziwei Feng
- Division of Urology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Jianteng Xie
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Feng Wen
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Menglei Jv
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Tiantian Liang
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Jing Li
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Yanhui Wang
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Yangyang Zuo
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Sheng Li
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Ruizhao Li
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Zhilian Li
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Bin Zhang
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Xinling Liang
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Shuangxin Liu
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Wei Shi
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
| | - Wenjian Wang
- Division of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences , Guangzhou , China
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17
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Li Z, Xiong C, Mo S, Tian H, Yu M, Mao T, Chen Q, Luo H, Li Q, Lu J, Zhao Y, Li W. Comprehensive Transcriptome Analyses of the Fructose-Fed Syrian Golden Hamster Liver Provides Novel Insights into Lipid Metabolism. PLoS One 2016; 11:e0162402. [PMID: 27589064 PMCID: PMC5010245 DOI: 10.1371/journal.pone.0162402] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 07/21/2016] [Indexed: 01/08/2023] Open
Abstract
Dyslipidemia has been widely proven to contribute to cardiovascular diseases and other metabolic disorders, especially in insulin resistance and type 2 diabetes. The overproduction of VLDL is a significant characteristic of dyslipidemia, indicating the dysfunction of hepatic lipid metabolism, from triglyceride synthesis to transport. The fructose-fed Syrian golden hamster is an established animal model for the study of VLDL assembly with insulin resistance, however, it remains unknown how VLDL production is regulated at the transcriptional level due to the absence of a complete hamster genome. Here, we performed deep sequencing and constructed an mRNA-miRNA-lncRNA interaction network of Syrian golden hamster liver in order to reveal the global transcription profile and find potential RNA molecular regulation of VLDL production. We identified 4,450 novel multi-exon hamster lncRNAs and 755 miRNAs expressed in liver. Additionally, 146 differentially expressed coding genes, 27 differentially expressed lncRNA genes, as well as 16 differentially expressed miRNAs were identified. We then constructed an mRNA-miRNA-lncRNA interaction network that may potentially regulate VLDL production, and interestingly found several microRNA-centered regulatory networks. In order to verify our interpretation, miR-486 was selected for further experiments. Overexpression or down-regulation of miR-486 in fructose-fed hamsters resulted in altered hepatic expression of proteins involved in VLDL production, and in modulated levels of circulating VLDL. Our findings implicated that miR-486 is a potential regulator of circulating VLDL levels. These results provide new insights and a valuable resource for further study of the molecular mechanisms of VLDL secretion.
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Affiliation(s)
- Ziyang Li
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Chaoliang Xiong
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Suo Mo
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Haiying Tian
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Mengqian Yu
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Tingting Mao
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Qian Chen
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Haitao Luo
- Key Laboratory of Intelligent Information Processing, Advanced Computer Research Center, State Key Laboratory of Computer Architecture, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Quanzhen Li
- Department of Immunology & Microarray Core Facility, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390, United States of America
| | - Jianxin Lu
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
- Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Yi Zhao
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
- Key Laboratory of Intelligent Information Processing, Advanced Computer Research Center, State Key Laboratory of Computer Architecture, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Wei Li
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
- Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, 325035, PR China
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18
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Update on the molecular biology of dyslipidemias. Clin Chim Acta 2016; 454:143-85. [DOI: 10.1016/j.cca.2015.10.033] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/24/2015] [Accepted: 10/30/2015] [Indexed: 12/20/2022]
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19
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Murata S, Ogawa K, Matsuzaka T, Chiba M, Nakayama K, Iwasaki K, Kurokawa T, Sano N, Tanoi T, Ohkohchi N. 1,8-Cineole Ameliorates Steatosis of Pten Liver Specific KO Mice via Akt Inactivation. Int J Mol Sci 2015; 16:12051-63. [PMID: 26023714 PMCID: PMC4490428 DOI: 10.3390/ijms160612051] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/15/2015] [Indexed: 01/21/2023] Open
Abstract
Hepatocyte-specific Phosphatase and tensin homolog (Pten)-knockout (KO) mice exhibit hepatic lesions analogous to non-alcoholic steatohepatitis (NASH). 1,8-cineole is a monoterpene oxide and it has several biological effects including hepatoprotective effects. In this study we revealed that 1,8-cineole ameliorates NASH of Pten KO mice. Pten KO mice were assigned to a control group without any medication or to a 1,8-cineole group injected with 50 mg/kg i.p. twice per week for eight weeks. At eight weeks, livers from each group were processed to measure triglyceride (TG) content, gene expression analysis, western blot analysis, and histological examination including Oil red O staining. 1,8-cineole ameliorated hepatic steatosis in Pten KO mice, revealed by TG content and Oil red O staining. Moreover, 1,8-cineole downregulated collagen 1a1 expression and improved liver fibrosis. Thus, 1,8-cineole has potential as a candidate to treat NASH by inactivating the Akt/PI3-kinase pathway.
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Affiliation(s)
- Soichiro Murata
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Koichi Ogawa
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Takashi Matsuzaka
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Mitsuru Chiba
- Department of Biomedical Sciences, Division of Medical Life Sciences, Graduate School of Health Sciences, Hirosaki University, Hirosaki, Aomori 036-8564, Japan.
| | - Ken Nakayama
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Kenichi Iwasaki
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Tomohiro Kurokawa
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Naoki Sano
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Tomohito Tanoi
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Nobuhiro Ohkohchi
- Department of Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
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20
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Armah CN, Derdemezis C, Traka MH, Dainty JR, Doleman JF, Saha S, Leung W, Potter JF, Lovegrove JA, Mithen RF. Diet rich in high glucoraphanin broccoli reduces plasma LDL cholesterol: Evidence from randomised controlled trials. Mol Nutr Food Res 2015; 59:918-26. [PMID: 25851421 PMCID: PMC4692095 DOI: 10.1002/mnfr.201400863] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/15/2015] [Accepted: 02/06/2015] [Indexed: 01/05/2023]
Abstract
SCOPE Cruciferous-rich diets have been associated with reduction in plasma LDL-cholesterol (LDL-C), which may be due to the action of isothiocyanates derived from glucosinolates that accumulate in these vegetables. This study tests the hypothesis that a diet rich in high glucoraphanin (HG) broccoli will reduce plasma LDL-C. METHODS AND RESULTS One hundred and thirty volunteers were recruited to two independent double-blind, randomly allocated parallel dietary intervention studies, and were assigned to consume either 400 g standard broccoli or 400 g HG broccoli per week for 12 weeks. Plasma lipids were quantified before and after the intervention. In study 1 (37 volunteers), the HG broccoli diet reduced plasma LDL-C by 7.1% (95% CI: -1.8%, -12.3%, p = 0.011), whereas standard broccoli reduced LDL-C by 1.8% (95% CI +3.9%, -7.5%, ns). In study 2 (93 volunteers), the HG broccoli diet resulted in a reduction of 5.1% (95% CI: -2.1%, -8.1%, p = 0.001), whereas standard broccoli reduced LDL-C by 2.5% (95% CI: +0.8%, -5.7%, ns). When data from the two studies were combined the reduction in LDL-C by the HG broccoli was significantly greater than standard broccoli (p = 0.031). CONCLUSION Evidence from two independent human studies indicates that consumption of high glucoraphanin broccoli significantly reduces plasma LDL-C.
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21
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Sendor AB, Hacker KE, Chen S, Corona AL, Sen O, Chiang DY, Snavely A, Rogers AB, Montgomery SA, Rathmell WK, McRee AJ. Von Hippel-Lindau status influences phenotype of liver cancers arising from PTEN loss. ACTA ACUST UNITED AC 2015; 5:61-71. [PMID: 25844041 PMCID: PMC4383253 DOI: 10.2147/gictt.s72274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND PTEN loss contributes to the development of liver diseases including hepatic steatosis and both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). The factors that influence the penetrance of these conditions are unclear. We explored the influence of sustained hypoxia signaling through co-deletion of Pten and Vhl in a murine model. METHODS We used a CreER-linked Keratin 18 mouse model to conditionally delete Pten, Vhl or both in somatic cells of adult mice, evaluating the resultant tumors by histology and gene expression microarray. Existing sets of gene expression data for human HCC and CC were examined for pathways related to those observed in the murine tumors, and a cohort of human CC samples was evaluated for relationships between HIF-1α expression and clinical outcomes. RESULTS Both Pten deletion genotypes developed liver tumors, but with differing phenotypes. Pten deletion alone led to large hepatic tumors with widespread hepatosteatosis. Co-deletion of Pten and Vhl with the Keratin 18 promoter resulted in reduced steatosis and a reduced tumor burden that was characterized by a trabecular architecture similar to CC. Genes associated with hepatic steatosis were coordinately expressed in the human HCC dataset, while genes involved in hypoxia response were upregulated in tumors from the human CC dataset. HIF-1α expression and overall survival were examined in an independent cohort of human CC tumors with no statistical differences uncovered. CONCLUSION Pten deletion in Keratin 18 expressing cells leads to aggressive tumor formation and widespread steatosis in mouse livers. Co-deletion of Vhl and Pten results in lower tumor burden with gene expression profiling suggesting a switch from a profile of lipid deposition to an expression profile more consistent with upregulation of the hypoxia response pathway. A relationship between tumor hypoxia signaling and altered hepatic steatotic response suggests that competing influences may alter tumor phenotypes.
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Affiliation(s)
- Adam B Sendor
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Kathryn E Hacker
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Shufen Chen
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Armando L Corona
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Oishee Sen
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Derek Y Chiang
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Anna Snavely
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Arlin B Rogers
- Section of Pathology, Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, Boston, MA, USA
| | - Stephanie A Montgomery
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - W Kimryn Rathmell
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Autumn J McRee
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
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22
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Peyrou M, Bourgoin L, Poher AL, Altirriba J, Maeder C, Caillon A, Fournier M, Montet X, Rohner-Jeanrenaud F, Foti M. Hepatic PTEN deficiency improves muscle insulin sensitivity and decreases adiposity in mice. J Hepatol 2015; 62:421-9. [PMID: 25234947 DOI: 10.1016/j.jhep.2014.09.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 09/03/2014] [Accepted: 09/09/2014] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS PTEN is a dual lipid/protein phosphatase, downregulated in steatotic livers with obesity or HCV infection. Liver-specific PTEN knockout (LPTEN KO) mice develop steatosis, inflammation/fibrosis and hepatocellular carcinoma with aging, but surprisingly also enhanced glucose tolerance. This study aimed at understanding the mechanisms by which hepatic PTEN deficiency improves glucose tolerance, while promoting fatty liver diseases. METHODS Control and LPTEN KO mice underwent glucose/pyruvate tolerance tests and euglycemic-hyperinsulinemic clamps. Body fat distribution was assessed by EchoMRI, CT-scan and dissection analyses. Primary/cultured hepatocytes and insulin-sensitive tissues were analysed ex vivo. RESULTS PTEN deficiency in hepatocytes led to steatosis through increased fatty acid (FA) uptake and de novo lipogenesis. Although LPTEN KO mice exhibited hepatic steatosis, they displayed increased skeletal muscle insulin sensitivity and glucose uptake, as assessed by euglycemic-hyperinsulinemic clamps. Surprisingly, white adipose tissue (WAT) depots were also drastically reduced. Analyses of key enzymes involved in lipid metabolism further indicated that FA synthesis/esterification was decreased in WAT. In addition, Ucp1 expression and multilocular lipid droplet structures were observed in this tissue, indicating the presence of beige adipocytes. Consistent with a liver to muscle/adipocyte crosstalk, the expression of liver-derived circulating factors, known to impact on muscle insulin sensitivity and WAT homeostasis (e.g. FGF21), was modulated in LPTEN KO mice. CONCLUSIONS Although steatosis develops in LPTEN KO mice, PTEN deficiency in hepatocytes promotes a crosstalk between liver and muscle, as well as adipose tissue, resulting in enhanced insulin sensitivity, improved glucose tolerance and decreased adiposity.
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Affiliation(s)
- Marion Peyrou
- Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, Switzerland
| | - Lucie Bourgoin
- Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, Switzerland
| | - Anne-Laure Poher
- Department of Internal Medicine Specialties, Division of Endocrinology, Diabetology, Hypertension and Nutrition, Faculty of Medicine, University of Geneva, Switzerland
| | - Jordi Altirriba
- Department of Internal Medicine Specialties, Division of Endocrinology, Diabetology, Hypertension and Nutrition, Faculty of Medicine, University of Geneva, Switzerland
| | - Christine Maeder
- Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, Switzerland
| | - Aurélie Caillon
- Department of Internal Medicine Specialties, Division of Endocrinology, Diabetology, Hypertension and Nutrition, Faculty of Medicine, University of Geneva, Switzerland
| | - Margot Fournier
- Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, Switzerland
| | - Xavier Montet
- Department of Radiology, Faculty of Medicine, University of Geneva, Switzerland
| | - Françoise Rohner-Jeanrenaud
- Department of Internal Medicine Specialties, Division of Endocrinology, Diabetology, Hypertension and Nutrition, Faculty of Medicine, University of Geneva, Switzerland
| | - Michelangelo Foti
- Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, Switzerland.
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23
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Lucas E, Cruces-Sande M, Briones AM, Salaices M, Mayor F, Murga C, Vila-Bedmar R. Molecular physiopathology of obesity-related diseases: multi-organ integration by GRK2. Arch Physiol Biochem 2015; 121:163-77. [PMID: 26643283 DOI: 10.3109/13813455.2015.1107589] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Obesity is a worldwide problem that has reached epidemic proportions both in developed and developing countries. The excessive accumulation of fat poses a risk to health since it favours the development of metabolic alterations including insulin resistance and tissue inflammation, which further contribute to the progress of the complex pathological scenario observed in the obese. In this review we put together the different outcomes of fat accumulation and insulin resistance in the main insulin-responsive tissues, and discuss the role of some of the key molecular routes that control disease progression both in an organ-specific and also in a more systemic manner. In particular, we focus on the importance of studying the integrated regulation of different organs and pathways that contribute to the global pathophysiology of this condition with a specific emphasis on the role of emerging key molecular nodes such as the G protein-coupled receptor kinase 2 (GRK2) signalling hub.
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Affiliation(s)
- Elisa Lucas
- a Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC) , Universidad Autónoma de Madrid , Madrid , Spain
- b Instituto de Investigación Sanitaria La Princesa , Madrid , Spain
| | - Marta Cruces-Sande
- a Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC) , Universidad Autónoma de Madrid , Madrid , Spain
- b Instituto de Investigación Sanitaria La Princesa , Madrid , Spain
| | - Ana M Briones
- c Departamento de Farmacología , Universidad Autónoma de Madrid (UAM) Madrid , Spain , and
- d Instituto de Investigación Hospital Universitario La Paz (IdiPAZ) Madrid , Spain
| | - Mercedes Salaices
- c Departamento de Farmacología , Universidad Autónoma de Madrid (UAM) Madrid , Spain , and
- d Instituto de Investigación Hospital Universitario La Paz (IdiPAZ) Madrid , Spain
| | - Federico Mayor
- a Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC) , Universidad Autónoma de Madrid , Madrid , Spain
- b Instituto de Investigación Sanitaria La Princesa , Madrid , Spain
| | - Cristina Murga
- a Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC) , Universidad Autónoma de Madrid , Madrid , Spain
- b Instituto de Investigación Sanitaria La Princesa , Madrid , Spain
| | - Rocio Vila-Bedmar
- a Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC) , Universidad Autónoma de Madrid , Madrid , Spain
- b Instituto de Investigación Sanitaria La Princesa , Madrid , Spain
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24
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Carter S, Li Z, Lemieux I, Alméras N, Tremblay A, Bergeron J, Poirier P, Deshaies Y, Després JP, Picard F. Circulating IGFBP-2 levels are incrementally linked to correlates of the metabolic syndrome and independently associated with VLDL triglycerides. Atherosclerosis 2014; 237:645-51. [PMID: 25463100 DOI: 10.1016/j.atherosclerosis.2014.09.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/08/2014] [Accepted: 09/02/2014] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To assess whether plasma IGFBP-2 is independently associated with components of the lipoprotein-lipid profile and to suggest a cutoff value that could identify subjects with the features of the metabolic syndrome. METHODS In this cross-sectional study, 379 Caucasian men from the general population and covering a wide range of BMI were recruited through the media. Subjects with type 2 diabetes, BMI values > 40 kg/m(2), or taking medication targeting glucose or lipid metabolism or blood pressure were excluded. Anthropometric data were collected and plasma IGFBP-2 concentrations, glucose tolerance and an extensive plasma lipid profile were determined after an overnight fast. RESULTS Subjects with low IGFBP-2 levels were characterized by increased fat mass (p < 0.0001), impaired insulin sensitivity (p < 0.0001) and higher plasma triglyceride (TG) levels (p < 0.0001). When divided into 6 quantiles, only subjects with the highest IGFBP-2 levels (>221.5 ng/mL) did not meet the NCEP ATP III criteria for the clinical diagnosis of the metabolic syndrome. In addition, circulating IGFBP-2 levels were significantly associated with VLDL-TG (r = -0.51, p < 0.0001) and HDL-C (r = -0.27, p < 0.0001) levels. After adjustments, plasma IGFBP-2 was found to be independently associated with VLDL-TG levels but not with HDL-C concentrations. CONCLUSIONS In our cohort, IGFBP-2 levels <221.5 ng/mL are incrementally associated with a detrimental plasma lipoprotein-lipid profile. After adjustment for covariates, IGFBP-2 remained independently associated with VLDL-TG but not HDL-C levels. This study supports further investigations in other populations and validation of IGFBP-2 as a biomarker of early dyslipidemia.
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Affiliation(s)
- Sophie Carter
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Faculty of Pharmacy, Université Laval, Québec, QC, Canada
| | - Zhuo Li
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada
| | - Isabelle Lemieux
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada
| | - Natalie Alméras
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Angelo Tremblay
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Jean Bergeron
- Lipid Research Center, CHU de Québec Research Center, Québec, QC, Canada
| | - Paul Poirier
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Faculty of Pharmacy, Université Laval, Québec, QC, Canada
| | - Yves Deshaies
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Department of Medicine, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Jean-Pierre Després
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Frédéric Picard
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada; Faculty of Pharmacy, Université Laval, Québec, QC, Canada.
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25
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Medina MW, Bauzon F, Naidoo D, Theusch E, Stevens K, Schilde J, Schubert C, Mangravite LM, Rudel LL, Temel RE, Runz H, Krauss RM. Transmembrane protein 55B is a novel regulator of cellular cholesterol metabolism. Arterioscler Thromb Vasc Biol 2014; 34:1917-23. [PMID: 25035345 DOI: 10.1161/atvbaha.113.302806] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Interindividual variation in pathways affecting cellular cholesterol metabolism can influence levels of plasma cholesterol, a well-established risk factor for cardiovascular disease. Inherent variation among immortalized lymphoblastoid cell lines from different donors can be leveraged to discover novel genes that modulate cellular cholesterol metabolism. The objective of this study was to identify novel genes that regulate cholesterol metabolism by testing for evidence of correlated gene expression with cellular levels of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) mRNA, a marker for cellular cholesterol homeostasis, in a large panel of lymphoblastoid cell lines. APPROACH AND RESULTS Expression array profiling was performed on 480 lymphoblastoid cell lines established from participants of the Cholesterol and Pharmacogenetics (CAP) statin clinical trial, and transcripts were tested for evidence of correlated expression with HMGCR as a marker of intracellular cholesterol homeostasis. Of these, transmembrane protein 55b (TMEM55B) showed the strongest correlation (r=0.29; P=4.0E-08) of all genes not previously implicated in cholesterol metabolism and was found to be sterol regulated. TMEM55B knockdown in human hepatoma cell lines promoted the decay rate of the low-density lipoprotein receptor, reduced cell surface low-density lipoprotein receptor protein, impaired low-density lipoprotein uptake, and reduced intracellular cholesterol. CONCLUSIONS Here, we report identification of TMEM55B as a novel regulator of cellular cholesterol metabolism through the combination of gene expression profiling and functional studies. The findings highlight the value of an integrated genomic approach for identifying genes that influence cholesterol homeostasis.
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Affiliation(s)
- Marisa W Medina
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.).
| | - Frederick Bauzon
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Devesh Naidoo
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Elizabeth Theusch
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Kristen Stevens
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Jessica Schilde
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Christian Schubert
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Lara M Mangravite
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Lawrence L Rudel
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Ryan E Temel
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Heiko Runz
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Ronald M Krauss
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
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Fisher E, Lake E, McLeod RS. Apolipoprotein B100 quality control and the regulation of hepatic very low density lipoprotein secretion. J Biomed Res 2014; 28:178-93. [PMID: 25013401 PMCID: PMC4085555 DOI: 10.7555/jbr.28.20140019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/15/2014] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein B (apoB) is the main protein component of very low density lipoprotein (VLDL) and is necessary for the assembly and secretion of these triglyceride (TG)-rich particles. Following release from the liver, VLDL is converted to low density lipoprotein (LDL) in the plasma and increased production of VLDL can therefore play a detrimental role in cardiovascular disease. Increasing evidence has helped to establish VLDL assembly as a target for the treatment of dyslipidemias. Multiple factors are involved in the folding of the apoB protein and the formation of a secretion-competent VLDL particle. Failed VLDL assembly can initiate quality control mechanisms in the hepatocyte that target apoB for degradation. ApoB is a substrate for endoplasmic reticulum associated degradation (ERAD) by the ubiquitin proteasome system and for autophagy. Efficient targeting and disposal of apoB is a regulated process that modulates VLDL secretion and partitioning of TG. Emerging evidence suggests that significant overlap exists between these degradative pathways. For example, the insulin-mediated targeting of apoB to autophagy and postprandial activation of the unfolded protein response (UPR) may employ the same cellular machinery and regulatory cues. Changes in the quality control mechanisms for apoB impact hepatic physiology and pathology states, including insulin resistance and fatty liver. Insulin signaling, lipid metabolism and the hepatic UPR may impact VLDL production, particularly during the postprandial state. In this review we summarize our current understanding of VLDL assembly, apoB degradation, quality control mechanisms and the role of these processes in liver physiology and in pathologic states.
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Affiliation(s)
- Eric Fisher
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Elizabeth Lake
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Roger S McLeod
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
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27
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Borén J, Taskinen MR, Olofsson SO, Levin M. Ectopic lipid storage and insulin resistance: a harmful relationship. J Intern Med 2013; 274:25-40. [PMID: 23551521 DOI: 10.1111/joim.12071] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity increases the risk of metabolic diseases, including insulin resistance and type 2 diabetes, as well as cardiovascular disease. In addition to lipid accumulation in adipose tissue, obesity is associated with increased lipid storage in ectopic tissues, such as skeletal muscle and liver. Furthermore, lipid accumulation in the heart may result in cardiac dysfunction and heart failure. It has recently been demonstrated that intracellular lipid accumulation in ectopic tissues leads to pathological responses and impaired insulin signalling. Here, we will review the current understanding of how lipid storage and lipid droplet physiology affect the risk of developing metabolic diseases.
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Affiliation(s)
- J Borén
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden.
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Sparks JD, Sparks CE, Adeli K. Selective hepatic insulin resistance, VLDL overproduction, and hypertriglyceridemia. Arterioscler Thromb Vasc Biol 2012; 32:2104-12. [PMID: 22796579 DOI: 10.1161/atvbaha.111.241463] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Insulin plays a central role in regulating energy metabolism, including hepatic transport of very low-density lipoprotein (VLDL)-associated triglyceride. Hepatic hypersecretion of VLDL and consequent hypertriglyceridemia leads to lower circulating high-density lipoprotein levels and generation of small dense low-density lipoproteins characteristic of the dyslipidemia commonly observed in metabolic syndrome and type 2 diabetes mellitus. Physiological fluctuations of insulin modulate VLDL secretion, and insulin inhibition of VLDL secretion upon feeding may be the first pathway to become resistant in obesity that leads to VLDL hypersecretion. This review summarizes the role of insulin-related signaling pathways that determine hepatic VLDL production. Disruption in signaling pathways that reduce generation of the second messenger phosphatidylinositide (3,4,5) triphosphate downstream of activated phosphatidylinositide 3-kinase underlies the development of VLDL hypersecretion. As insulin resistance progresses, a number of pathways are altered that further augment VLDL hypersecretion, including hepatic inflammatory pathways. Insulin plays a complex role in regulating glucose metabolism, and it is not surprising that the role of insulin in VLDL and lipid metabolism will prove equally complex.
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Affiliation(s)
- Janet D Sparks
- University of Rochester Medical Center, Department of Pathology and Laboratory Medicine, Rochester, NY, USA
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30
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Liu M, Chung S, Shelness GS, Parks JS. Hepatic ABCA1 and VLDL triglyceride production. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1821:770-7. [PMID: 22001232 PMCID: PMC3272310 DOI: 10.1016/j.bbalip.2011.09.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 09/23/2011] [Accepted: 09/26/2011] [Indexed: 02/04/2023]
Abstract
Elevated plasma triglyceride (TG) and reduced high density lipoprotein (HDL) concentrations are prominent features of metabolic syndrome (MS) and type 2 diabetes (T2D). Individuals with Tangier disease also have elevated plasma TG concentrations and a near absence of HDL, resulting from mutations in ATP binding cassette transporter A1 (ABCA1), which facilitates the efflux of cellular phospholipid and free cholesterol to assemble with apolipoprotein A-I (apoA-I), forming nascent HDL particles. In this review, we summarize studies focused on the regulation of hepatic very low density lipoprotein (VLDL) TG production, with particular attention on recent evidence connecting hepatic ABCA1 expression to VLDL, LDL, and HDL metabolism. Silencing ABCA1 in McArdle rat hepatoma cells results in diminished assembly of large (>10nm) nascent HDL particles, diminished PI3 kinase activation, and increased secretion of large, TG-enriched VLDL1 particles. Hepatocyte-specific ABCA1 knockout (HSKO) mice have a similar plasma lipid phenotype as Tangier disease subjects, with a two-fold elevation of plasma VLDL TG, 50% lower LDL, and 80% reduction in HDL concentrations. This lipid phenotype arises from increased hepatic secretion of VLDL1 particles, increased hepatic uptake of plasma LDL by the LDL receptor, elimination of nascent HDL particle assembly by the liver, and hypercatabolism of apoA-I by the kidney. These studies highlight a novel role for hepatic ABCA1 in the metabolism of all three major classes of plasma lipoproteins and provide a metabolic link between elevated TG and reduced HDL levels that are a common feature of Tangier disease, MS, and T2D. This article is part of a Special Issue entitled: Triglyceride Metabolism and Disease.
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Affiliation(s)
- Mingxia Liu
- Department of Pathology/Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA
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31
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Qin B, Anderson RA, Kuzuya T, Kitaura Y, Shimomura Y. Multiple factors and pathways involved in hepatic very low density lipoprotein-apoB100 overproduction in Otsuka Long-Evans Tokushima Fatty rats. Atherosclerosis 2012; 222:409-16. [PMID: 22546076 DOI: 10.1016/j.atherosclerosis.2012.03.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 03/02/2012] [Accepted: 03/29/2012] [Indexed: 01/04/2023]
Abstract
AIMS Overproduction of hepatic very low-density lipoprotein (VLDL) particles is a major abnormality of lipoprotein dysregulation in type 2 diabetes (T2D). We sought to examine the relationship between systemic/hepatic inflammation associated with insulin resistance and apolipoprotein (apo)B100-containing VLDL production. METHODS AND RESULTS At the age of 19 wks, Otsuka Long-Evans Tokushima Fatty (OLETF) rats showed systemic inflammation (plasma TNF-α and interleukin (IL)-6 levels increased), insulin resistance (plasma retinol binding protein 4 and soluble CD36 levels were higher), dyslipidemia and fatty liver (plasma and liver triglyceride and cholesterol levels were higher as well as total VLDL-, VLDL(1)-, VLDL(2)-apoB100 and VLDL-triglycerides were overproduced), compared with the control rats. In livers of OLETF rats, mRNA levels of tnf, il1b and il6 were increased, but an anti-inflammatory protein, zinc finger protein 36, and its mRNA expression were decreased. We also found that the liver mRNA, protein levels, and tyrosine phosphorylation (pY) of insulin receptor (InsR) substrate (IRS) 2, but not IRS1, were decreased in OLETF rats; pY of InsR and Akt protein and phospho-Akt (ser437) were also reduced; but protein tyrosine phosphatase-1B protein was overexpressed. The gene expressions of glucose transporters 1 and 2, and glycogen synthase were decreased, but phosphatase and tensin homolog deleted on chromosome ten and glycogen synthase kinase 3β mRNAs were overexpressed, compared with the controls. Sterol regulatory element binding protein-1c mRNA, ATP-binding cassette transporter A1 mRNA, microsomal triglyceride transfer protein mRNA/protein, and CD36 mRNA/protein levels were increased and lipoprotein lipase and Niemann-Pick c1-like1 mRNA levels were decreased, which are all involved in lipogenesis. Decreased sirtuins1-3 mRNA levels were also observed in OLETF rats. CONCLUSIONS These abnormal genes, proteins expression and phosphorylation of multiple pathways related to inflammatory, insulin signaling and lipogenesis may be important underlying factors in VLDL-apoB100 particles overproduction observed in T2D. Our data contribute to the further understanding of an association of dyslipoproteinemia with systemic metabolic disorders, fatty liver and dysregulated hepatic metabolic pathways.
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Affiliation(s)
- Bolin Qin
- United States Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics and Immunology Laboratory, Beltsville, MD 20705, USA.
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Davies EM, Sheffield DA, Tibarewal P, Fedele CG, Mitchell CA, Leslie NR. The PTEN and Myotubularin phosphoinositide 3-phosphatases: linking lipid signalling to human disease. Subcell Biochem 2012; 58:281-336. [PMID: 22403079 DOI: 10.1007/978-94-007-3012-0_8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two classes of lipid phosphatases selectively dephosphorylate the 3 position of the inositol ring of phosphoinositide signaling molecules: the PTEN and the Myotubularin families. PTEN dephosphorylates PtdIns(3,4,5)P(3), acting in direct opposition to the Class I PI3K enzymes in the regulation of cell growth, proliferation and polarity and is an important tumor suppressor. Although there are several PTEN-related proteins encoded by the human genome, none of these appear to fulfill the same functions. In contrast, the Myotubularins dephosphorylate both PtdIns(3)P and PtdIns(3,5)P(2), making them antagonists of the Class II and Class III PI 3-kinases and regulators of membrane traffic. Both phosphatase groups were originally identified through their causal mutation in human disease. Mutations in specific myotubularins result in myotubular myopathy and Charcot-Marie-Tooth peripheral neuropathy; and loss of PTEN function through mutation and other mechanisms is evident in as many as a third of all human tumors. This chapter will discuss these two classes of phosphatases, covering what is known about their biochemistry, their functions at the cellular and whole body level and their influence on human health.
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Affiliation(s)
- Elizabeth M Davies
- Division of Cell Signalling and Immunology, Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dow Street, DD1 5EH, Dundee, Scotland, United Kingdom,
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Moon BC, Hernandez-Ono A, Stiles B, Wu H, Ginsberg HN. Apolipoprotein B secretion is regulated by hepatic triglyceride, and not insulin, in a model of increased hepatic insulin signaling. Arterioscler Thromb Vasc Biol 2011; 32:236-46. [PMID: 22155452 DOI: 10.1161/atvbaha.111.241356] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE States of insulin resistance, hyperinsulinemia, and hepatic steatosis are associated with increased secretion of triglycerides (TG) and apolipoprotein B (apoB), even though insulin targets apoB for degradation. We used hepatic-specific "phosphatase and tensin homologue deleted on chromosome 10" (Pten) knockout (hPten-ko) mice, with increased hepatic insulin signaling, to determine the relative roles of insulin signaling and hepatic TG in regulating apoB secretion. METHODS AND RESULTS TG and apoB secretion was elevated in hPten-ko mice. When hepatic TG was reduced by inhibition of diacylglycerol acyltransferase 1/diacylglycerol acyltransferase 2 or sterol regulatory element-binding protein-1c, both TG secretion and apoB secretion fell without changes in hepatic insulin signaling. Acute reconstitution of hPten reduced hepatic TG content, and both TG and apoB secretion fell within 4 days despite decreased hepatic insulin signaling. Acute depletion of hepatic Pten by adenoviral introduction of Cre into Pten floxed mice caused steatosis within 4 days, and secretion of both TG and apoB increased despite increased hepatic insulin signaling. Even when steatosis after acute Pten depletion was prevented by pretreatment with SREBP-1c antisense oligonucleotides, apoB secretion was not reduced after 4 days. Ex vivo results were in primary hepatocytes were similar. CONCLUSIONS Either hepatic TG is the dominant regulator of apoB secretion or any inhibitory effects of hepatic insulin signaling on apoB secretion is very short-lived.
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Affiliation(s)
- Byoung C Moon
- Irving Institute for Clinical and Translational Research, PH10-305, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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Zhao Y, Pennings M, Vrins CL, Calpe-Berdiel L, Hoekstra M, Kruijt JK, Ottenhoff R, Hildebrand RB, van der Sluis R, Jessup W, Le Goff W, Chapman MJ, Huby T, Groen AK, Van Berkel TJ, Van Eck M. Hypocholesterolemia, foam cell accumulation, but no atherosclerosis in mice lacking ABC-transporter A1 and scavenger receptor BI. Atherosclerosis 2011; 218:314-22. [DOI: 10.1016/j.atherosclerosis.2011.07.096] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 06/23/2011] [Accepted: 07/14/2011] [Indexed: 10/17/2022]
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Gambino R, Musso G, Cassader M. Redox balance in the pathogenesis of nonalcoholic fatty liver disease: mechanisms and therapeutic opportunities. Antioxid Redox Signal 2011; 15:1325-65. [PMID: 20969475 DOI: 10.1089/ars.2009.3058] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is currently the most common liver disease in the world. It encompasses a histological spectrum, ranging from simple, nonprogressive steatosis to nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis and hepatocellular carcinoma. While liver-related complications are confined to NASH, emerging evidence suggests both simple steatosis and NASH predispose to type 2 diabetes and cardiovascular disease. The pathogenesis of NAFLD is currently unknown, but accumulating data suggest that oxidative stress and altered redox balance play a crucial role in the pathogenesis of steatosis, steatohepatitis, and fibrosis. We will examine intracellular mechanisms, including mitochondrial dysfunction and impaired oxidative free fatty acid metabolism, leading to reactive oxygen species generation; additionally, the potential pathogenetic role of extracellular sources of reactive oxygen species in NAFLD, including increased myeloperoxidase activity and oxidized low density lipoprotein accumulation, will be reviewed. We will discuss how these mechanisms converge to determine the whole pathophysiological spectrum of NAFLD, including hepatocyte triglyceride accumulation, hepatocyte apoptosis, hepatic inflammation, hepatic stellate cell activation, and fibrogenesis. Finally, available animal and human data on treatment opportunities with older and newer antioxidant will be presented.
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Affiliation(s)
- Roberto Gambino
- Department of Internal Medicine, University of Turin, Turin, Italy
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36
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Hussain MM, Nijstad N, Franceschini L. Regulation of microsomal triglyceride transfer protein. ACTA ACUST UNITED AC 2011; 6:293-303. [PMID: 21808658 DOI: 10.2217/clp.11.21] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Microsomal triglyceride transfer protein (MTP) facilitates the transport of dietary and endogenous fat by the intestine and liver by assisting in the assembly and secretion of triglyceride-rich apolipoprotein B-containing lipoproteins. Higher concentrations of apolipoprotein B lipoproteins predispose individuals to various cardiovascular and metabolic diseases such as atherosclerosis, diabetes, obesity and the metabolic syndrome. These can potentially be avoided by reducing MTP activity. In this article, we discuss regulation of MTP during development, cellular differentiation and diurnal variation. Furthermore, we focus on the regulation of MTP that occurs at transcriptional, post-transcriptional and post-translational levels. Transcriptional regulation of MTP depends on a few highly conserved cis-elements in the promoter. Several transcription factors that bind to these elements and either increase or decrease MTP expression have been identified. Additionally, MTP is regulated by macronutrients, hormones and other factors. This article will address the many ways in which MTP is regulated and advance the idea that reducing MTP levels, rather than its inhibition, might be an option to lower plasma lipids.
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Affiliation(s)
- M Mahmood Hussain
- Departments of Cell Biology and Pediatrics, The State University of New York, Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
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Qiu W, Zhang J, Dekker MJ, Wang H, Huang J, Brumell JH, Adeli K. Hepatic autophagy mediates endoplasmic reticulum stress-induced degradation of misfolded apolipoprotein B. Hepatology 2011; 53:1515-25. [PMID: 21360721 DOI: 10.1002/hep.24269] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
UNLABELLED Induction of endoplasmic reticulum (ER) stress was previously shown to impair hepatic apolipoprotein B100 (apoB) production by enhancing cotranslational and posttranslational degradation of newly synthesized apoB. Here, we report the involvement of autophagy in ER stress-induced degradation of apoB and provide evidence for a significant role of autophagy in regulating apoB biogenesis in primary hepatocyte systems. Induction of ER stress following short-term glucosamine treatment of McA-RH7777 cells resulted in significantly increased colocalization of apoB with green fluorescent protein-microtubule-associated protein 1 light chain 3 (GFP-LC3), referred to as apoB-GFP-LC3 puncta, in a dose-dependent manner. Colocalization with this autophagic marker correlated positively with the reduction in newly synthesized apoB100. Treatment of McA-RH7777 cells with 4-phenyl butyric acid, a chemical ER stress inhibitor, prevented glucosamine- and tunicamycin-induced increases in GRP78 and phosphorylated eIF2α, rescued newly synthesized [(35) S]-labeled apoB100, and substantially blocked the colocalization of apoB with GFP-LC3. Autophagic apoB degradation was also observed in primary rat and hamster hepatocytes at basal conditions as well as upon the induction of ER stress. In contrast, this pathway was inactive in HepG2 cells under ER stress conditions, unless proteasomal degradation was blocked with N-acetyl-leucinyl-leucinyl-norleucinal and the medium was supplemented with oleate. Transient transfection of McA-RH7777 cells with a wild-type protein kinase R-like ER kinase (PERK) complementary DNA resulted in dramatic induction of apoB autophagy. In contrast, transfection with a kinase inactive mutant PERK gave rise to reduced apoB autophagy, suggesting that apoB autophagy may occur via a PERK signaling-dependent mechanism. CONCLUSION Taken together, these data suggest that induction of ER stress leads to markedly enhanced apoB autophagy in a PERK-dependent pathway, which can be blocked with the chemical chaperone 4-phenyl butyric acid. ApoB autophagy rather than proteasomal degradation may be a more pertinent physiological mechanism regulating hepatic lipoprotein production in primary hepatocytes.
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Affiliation(s)
- Wei Qiu
- The Hospital for Sick Children, University of Toronto, Ontario,Canada
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Abstract
It is well established that the development of NAFLD and NASH are closely linked to an excess flow of free fatty acids (FFA) arising from dysfunctional/insulin resistant adipose tissue causing ectopic fat deposition in many organs. In the liver, when chronic lipid supply surpasses the metabolic ability to adapt it will induce hepatocellular damage as FFA are redirected into harmful pathways of non-oxidative metabolism with intracellular accumulation of toxic lipid-derived metabolites. Multiple mechanisms have been implicated including mitochondrial dysfunction, endoplasmic reticulum stress, and activation of multiple inflammatory pathways. Understanding the role of insulin resistance and lipotoxicity in NASH as part of a broader metabolic disorder is likely to assist practitioners in the successful management of these challenging patients.
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Affiliation(s)
- Kenneth Cusi
- Diabetes Division, The University of Texas Health Science Center at San Antonio, Room 3.380S, 7703 Floyd Curl Drive, San Antonio, TX 78284-3900, USA.
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Abstract
PURPOSE OF REVIEW To increase awareness about the close interrelationship between nonalcoholic fatty liver disease and type 2 diabetes mellitus, and of recent diagnostic and treatment advances in the field. RECENT FINDINGS The perception of nonalcoholic fatty liver disease as an uncommon and benign condition is rapidly changing. Approximately 70% of persons with type 2 diabetes mellitus have a fatty liver and the disease follows a more aggressive course with necroinflammation and fibrosis (i.e. nonalcoholic steatohepatitis) in diabetes. New evidence suggests that it is not steatosis per se but the development of lipotoxicity-induced mitochondrial dysfunction and activation of inflammatory pathways that leads to progressive liver damage. Nonalcoholic steatohepatitis is a leading cause of end-stage liver disease and contributes to cardiovascular disease in patients with type 2 diabetes mellitus. Because nonalcoholic steatohepatitis may develop even in the presence of normal liver transaminases, a liver biopsy is still necessary for a definitive diagnosis. However, new imaging methods and plasma biomarkers are emerging as alternative diagnostic tools. Lifestyle intervention is the gold standard for the management of nonalcoholic steatohepatitis. Recent randomized controlled trials suggest thiazolidiendiones are promising therapeutic agents. SUMMARY Nonalcoholic steatohepatitis is a frequently overlooked and potentially severe complication of type 2 diabetes mellitus. Patients may benefit from its early diagnosis and treatment.
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Affiliation(s)
- Kenneth Cusi
- Diabetes Division, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78284-3900, USA.
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