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Bisgaard LS, Christoffersen C. The apoM/S1P Complex-A Mediator in Kidney Biology and Disease? Front Med (Lausanne) 2021; 8:754490. [PMID: 34722589 PMCID: PMC8553247 DOI: 10.3389/fmed.2021.754490] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/16/2021] [Indexed: 12/18/2022] Open
Abstract
Kidney disease affects more than 10% of the population, can be both acute and chronic, and is linked to other diseases such as cardiovascular disease, diabetes, and sepsis. Despite the detrimental consequences for patients, no good treatment options directly targeting the kidney are available. Thus, a better understanding of the pathology and new treatment modalities are required. Accumulating evidence suggests that the apolipoprotein M/sphingosine-1-phosphate (apoM/S1P) axis is a likely drug target, but significant gaps in our knowledge remain. In this review, we present what has so far been elucidated about the role of apoM in normal kidney biology and describe how changes in the apoM/S1P axis are thought to affect the development of kidney disease. ApoM is primarily produced in the liver and kidneys. From the liver, apoM is secreted into circulation, where it is attached to lipoproteins (primarily HDL). Importantly, apoM is a carrier of the bioactive lipid S1P. S1P acts by binding to five different receptors. Together, apoM/S1P plays a role in several biological mechanisms, such as inflammation, endothelial cell permeability, and lipid turnover. In the kidney, apoM is primarily expressed in the proximal tubular cells. S1P can be produced locally in the kidney, and several of the five S1P receptors are present in the kidney. The functional role of kidney-derived apoM as well as plasma-derived apoM is far from elucidated and will be discussed based on both experimental and clinical studies. In summary, the current studies provide evidence that support a role for the apoM/S1P axis in kidney disease; however, additional pre-clinical and clinical studies are needed to reveal the mechanisms and target potential in the treatment of patients.
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Affiliation(s)
- Line S Bisgaard
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christina Christoffersen
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Apolipoprotein M: Research Progress and Clinical Perspective. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1276:85-103. [PMID: 32705596 DOI: 10.1007/978-981-15-6082-8_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Apolipoprotein M (apoM) was first identified and characterized to the apolipoprotein family in 1999. Human apoM gene is located in a highly conserved segment in the major histocompatibility complex (MHC) class III locus on chromosome 6 and codes for an about 23 kDa protein that structurally belongs to the lipocalin superfamily. ApoM is selectively expressed in hepatocytes and in the tubular epithelium of kidney. In human plasma, apoM is mainly confined to the high-density lipoprotein (HDL) particles, but it may also occur in other lipoprotein classes, such as in the triglyceride-rich particles after fat intake. It has been demonstrated that apoM is critical for the formation of HDL, notably pre-beta HDL1. The antiatherogenic function of HDL is well established, and its ability to promote cholesterol efflux from foam cells in the atherosclerotic lesions is generally regarded as one of the key mechanisms behind this protective function. However, HDL could also display a variety of properties that may affect the complex atherosclerotic processes by other mechanisms, thus being involved in processes related to antioxidant defense, immune system, and systemic effects in septicemia, which may be partly contributed via its apolipoproteins and/or phospholipids. Moreover, it has been demonstrated that apoM functions as a natural carrier of sphingosin-1-phosphate (S1P) in vivo which may be related to its antiatherosclerotic and protective effects on endothelial cell barrier and anti-inflammatory properties. These may also provide a link between the diverse effects of HDL.
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Pingitore P, Sasidharan K, Ekstrand M, Prill S, Lindén D, Romeo S. Human Multilineage 3D Spheroids as a Model of Liver Steatosis and Fibrosis. Int J Mol Sci 2019; 20:ijms20071629. [PMID: 30986904 PMCID: PMC6480107 DOI: 10.3390/ijms20071629] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 03/29/2019] [Accepted: 03/30/2019] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in western countries. Despite the high prevalence of NAFLD, the underlying biology of the disease progression is not clear, and there are no approved drugs to treat non-alcoholic steatohepatitis (NASH), the most advanced form of the disease. Thus, there is an urgent need for developing advanced in vitro human cellular systems to study disease mechanisms and drug responses. We attempted to create an organoid system genetically predisposed to NAFLD and to induce steatosis and fibrosis in it by adding free fatty acids. We used multilineage 3D spheroids composed by hepatocytes (HepG2) and hepatic stellate cells (LX-2) with a physiological ratio (24:1). HepG2 and LX-2 cells are homozygotes for the PNPLA3 I148M sequence variant, the strongest genetic determinant of NAFLD. We demonstrate that hepatic stellate cells facilitate the compactness of 3D spheroids. Then, we show that the spheroids develop accumulations of fat and collagen upon exposure to free fatty acids. Finally, this accumulation was rescued by incubating spheroids with liraglutide or elafibranor, drugs that are in clinical trials for the treatment of NASH. In conclusion, we have established a simple, easy to handle, in vitro model of genetically induced NAFLD consisting of multilineage 3D spheroids. This tool may be used to understand molecular mechanisms involved in the early stages of fibrogenesis induced by lipid accumulation. Moreover, it may be used to identify new compounds to treat NASH using high-throughput drug screening.
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Affiliation(s)
- Piero Pingitore
- Department of Molecular and Clinical Medicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden.
| | - Kavitha Sasidharan
- Department of Molecular and Clinical Medicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden.
| | - Matias Ekstrand
- Department of Molecular and Clinical Medicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden.
| | - Sebastian Prill
- Cardiovascular, Renal and Metabolism, IMED Biotech Unit, AstraZeneca, SE-431 83 Gothenburg, Sweden.
| | - Daniel Lindén
- Cardiovascular, Renal and Metabolism, IMED Biotech Unit, AstraZeneca, SE-431 83 Gothenburg, Sweden.
- Division of Endocrinology, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, SE-405 30 Gothenburg, Sweden.
| | - Stefano Romeo
- Department of Molecular and Clinical Medicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden.
- Clinical Nutrition Unit, Department of Medical and Surgical Sciences, Magna Graecia University, 88100 Catanzaro, Italy.
- Cardiology Department, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden.
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Fernandez AGL, Crescenzi B, Pierini V, Di Battista V, Barba G, Pellanera F, Di Giacomo D, Roti G, Piazza R, Adelman ER, Figueroa ME, Mecucci C. A distinct epigenetic program underlies the 1;7 translocation in myelodysplastic syndromes. Leukemia 2019; 33:2481-2494. [PMID: 30923319 DOI: 10.1038/s41375-019-0433-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/23/2018] [Accepted: 02/08/2019] [Indexed: 02/06/2023]
Abstract
The unbalanced translocation dic(1;7)(q10;p10) in myelodysplastic syndromes (MDS) is originated by centromeric juxtaposition resulting into 1q trisomy and 7q monosomy. More than half of cases arise after chemo/radio-therapy. To date, given the absence of genes within the centromeric regions, no specific molecular events have been identified in this cytogenetic subgroup. We performed the first comprehensive genetic and epigenetic analysis of MDS with dic(1;7)(q10;p10) compared to normal controls and therapy-related myeloid neoplasms (t-MNs). RNA-seq showed a unique downregulated signature in dic(1;7) cases, affecting more than 80% of differentially expressed genes. As revealed by pathway and gene ontology analyses, downregulation of ATP-binding cassette (ABC) transporters and lipid-related genes and upregulation of p53 signaling were the most relevant biological features of dic(1;7). Epigenetic supervised analysis revealed hypermethylation at intronic enhancers in the dicentric subgroup, in which low expression levels of enhancer putative target genes accounted for around 35% of the downregulated signature. Enrichment of Krüppel-like transcription factor binding sites emerged at enhancers. Furthermore, a specific hypermethylated pattern on 1q was found to underlie the hypo-expression of more than 50% of 1q-deregulated genes, despite trisomy. In summary, dic(1;7) in MDS establishes a specific transcriptional program driven by a unique epigenomic signature.
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Affiliation(s)
| | - Barbara Crescenzi
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy
| | - Valentina Pierini
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy
| | - Valeria Di Battista
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy
| | - Gianluca Barba
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy
| | - Fabrizia Pellanera
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy
| | - Danika Di Giacomo
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy
| | | | - Rocco Piazza
- Hematology, School of Medicine and Surgery, University of Milano Bicocca, Milano, Italy
| | - Emmalee R Adelman
- Sylvester Comprehensive Cancer Center and Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Maria E Figueroa
- Sylvester Comprehensive Cancer Center and Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Cristina Mecucci
- Department of Medicine, Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, Italy.
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Wei J, Yu Y, Luo GH, Feng YH, Shi YP, Zhang J, Mu QF, Yu MM, Pan LL, Berggren-Söderlund M, Nilsson-Ehle P, Zhang XY, Xu N. 17β-estradiol regulates the expression of apolipoprotein M through estrogen receptor α-specific binding motif in its promoter. Lipids Health Dis 2017; 16:66. [PMID: 28359281 PMCID: PMC5374570 DOI: 10.1186/s12944-017-0458-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 03/20/2017] [Indexed: 11/17/2022] Open
Abstract
Background We have previously demonstrated that estrogen could significantly enhance expression of apolipoprotein M (apoM), whereas the molecular basis of its mechanism is not fully elucidated yet. To further investigate the mechanism behind the estrogen induced up-regulation of apoM expression. Results Our results demonstrated either free 17β-estradiol (E2) or membrane-impermeable bovine serum albumin-conjugated E2 (E2-BSA) could modulate human apoM gene expression via the estrogen receptor alpha (ER-α) pathway in the HepG2 cells. Moreover, experiments with the luciferase activity analysis of truncated apoM promoters could demonstrate that a regulatory region (from-1580 to −1575 bp (−GGTCA-)) upstream of the transcriptional start site of apoM gene was essential for the basal transcriptional activity that regulated by the ER-α. With the applications of an electrophoresis mobility shift assay and a chromatin immunoprecipitation assay, we could successfully identify a specific ER-α binding element in the apoM promoter region. Conculsion In summary, the present study indicates that 17β-estradiol induced up-regulation of apoM in HepG2 cells is through an ER-α-dependent pathway involving ER-α binding element in the promoter of the apoM gene.
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Affiliation(s)
- Jiang Wei
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Yang Yu
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Guang-Hua Luo
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Yue-Hua Feng
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Yuan-Ping Shi
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Jun Zhang
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Qin-Feng Mu
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Miao-Mei Yu
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Li-Li Pan
- Department of Comprehensive Laboratory, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Maria Berggren-Söderlund
- Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lunds University, S-221 85, Lund, Sweden
| | - Peter Nilsson-Ehle
- Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lunds University, S-221 85, Lund, Sweden
| | - Xiao-Ying Zhang
- Cardiothoracic Surgery, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, China
| | - Ning Xu
- Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lunds University, S-221 85, Lund, Sweden.
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Zhang Y, Huang LZ, Yang QL, Liu Y, Zhou X. Correlation analysis between ApoM gene-promoter polymorphisms and coronary heart disease. Cardiovasc J Afr 2017; 27:228-237. [PMID: 27841911 PMCID: PMC5340899 DOI: 10.5830/cvja-2016-001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 01/08/2016] [Indexed: 11/17/2022] Open
Abstract
Objectives: Apolipoprotein M (ApoM), a 25-kDa plasma protein belonging to the lipocalin protein family, is predominantly associated with high-density lipoprotein cholesterol (HDL-C). Studies have suggested ApoM to be important for the formation of pre-β-HDL and to increase cholesterol efflux from macrophage foam cells. The aim of this study was to explore the association of single-nucleotide polymorphisms(SNPs) in the ApoM promoter with coronary atherosclerotic disease (CAD), and the contribution of latent factors. Methods: ApoM was measured in samples from two separate case–control studies, of whom 88 patients developed CAD and 88 were controls. Whole-blood samples from subjects were genotyped by PCR-restriction fragment length polymorphism (PCR-RFLP). Luciferase activities were measured for HepG2 cells with two SNPs, rs805296 (T-778C) and rs940494 (T-855C), and after interfering with or overexpressing the predicted transcription factors. The ability of the SNPs to combine with nucleoproteins was analysed by electophoretic mobility shift assay (EMSA). Results: Mean plasma ApoM concentrations in the CAD and non-CAD groups were 9.58 ± 4.30 and 12.22 ± 6.59 μg/ ml, respectively. Correlation studies of ApoM concentrations with several analytes showed a marked positive correlation with HDL-C, fasting plasma glucose and triglyceride levels. The CC genotype showed lower luciferase activities compared to the TC and TT genotypes. The ApoM-855 mutant-typecould bind to the AP-2α. Interference and overexpression of AP-2 increased and decreased luciferase activities of the wild and mutant types to different degrees. Conclusion:: ApoM may be a biomarker of CAD. ApoM- 855 T→C substitution provides binding sites for AP-2α and reduces ApoM transcription activity.
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Affiliation(s)
- Yao Zhang
- Department of Biochemistry and Molecular Biology, Wan Nan Medical College, Anhui 241000, China.
| | - Li-Zhu Huang
- Clinical Testing and Diagnosis, Experimental Centre of Bengbu Medical College, Anhui 233000, China
| | - Qing-Ling Yang
- Department of Biochemistry and Molecular Biology, Beng Bu Medical College, Anhui 233000, China
| | - Yan Liu
- Clinical Testing and Diagnosis, Experimental Centre of Bengbu Medical College, Anhui 233000, China
| | - Xin Zhou
- Centre for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Peoples' Republic of China
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Ren K, Mo ZC, Liu X, Tang ZL, Jiang Y, Peng XS, Zhang QH, Shi JF, Yi GH. TGF-β Down-regulates Apolipoprotein M Expression through the TAK-1-JNK-c-Jun Pathway in HepG2 Cells. Lipids 2016; 52:109-117. [PMID: 28039587 DOI: 10.1007/s11745-016-4227-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 12/14/2016] [Indexed: 12/22/2022]
Abstract
Apolipoprotein M (apoM) is a relatively novel apolipoprotein that plays pivotal roles in many dyslipidemia-associated diseases; however, its regulatory mechanisms are poorly understood. Many cytokines have been identified that down-regulate apoM expression in HepG2 cells, among which transforming growth factor-β (TGF-β) exerts the most potent effects. In addition, c-Jun, a member of the activated protein 1 (AP-1) family whose activity is modulated by c-Jun N-terminal kinase (JNK), decreases apoM expression at the transcriptional level by binding to the regulatory element in the proximal apoM promoter. In this study, we investigated the molecular mechanisms through which TGF-β decreases the apoM level in HepG2 cells. The results revealed that TGF-β inhibited apoM expression at both the mRNA and protein levels in a dose- and time-dependent manner and that it suppressed apoM secretion. These effects were attenuated by treatment of cells with either SP600125 (JNK inhibitor) or c-Jun siRNA. 5Z-7-oxozeaenol [(a TGF-β-activated kinase 1 (TAK-1) inhibitor)] also attenuated the TGF-β-mediated inhibition of apoM expression and suppressed the activation of JNK and c-Jun. These results have demonstrated that TGF-β suppresses apoM expression through the TAK-1-JNK-c-Jun pathway in HepG2 cells.
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Affiliation(s)
- Kun Ren
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, 28 W Changsheng Road, Hengyang, 421001, Hunan, China
| | - Zhong-Cheng Mo
- Department of Histology and Embryology, University of South China, Hengyang, 421001, Hunan, China
| | - Xing Liu
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
| | - Zhen-Li Tang
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, 28 W Changsheng Road, Hengyang, 421001, Hunan, China
| | - Yue Jiang
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, 28 W Changsheng Road, Hengyang, 421001, Hunan, China
| | - Xiao-Shan Peng
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, 28 W Changsheng Road, Hengyang, 421001, Hunan, China
| | - Qing-Hai Zhang
- Clinical Research Institution, The First Affiliated Hospital, University of South China, Hengyang, 421001, Hunan, China
| | - Jin-Feng Shi
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, 28 W Changsheng Road, Hengyang, 421001, Hunan, China.,Department of Histology and Embryology, University of South China, Hengyang, 421001, Hunan, China
| | - Guang-Hui Yi
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, 28 W Changsheng Road, Hengyang, 421001, Hunan, China.
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8
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Frej C, Linder A, Happonen KE, Taylor FB, Lupu F, Dahlbäck B. Sphingosine 1-phosphate and its carrier apolipoprotein M in human sepsis and in Escherichia coli sepsis in baboons. J Cell Mol Med 2016; 20:1170-81. [PMID: 26990127 PMCID: PMC4882985 DOI: 10.1111/jcmm.12831] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 02/07/2016] [Indexed: 01/01/2023] Open
Abstract
Sphingosine 1‐phosphate (S1P) is an important regulator of vascular integrity and immune cell migration, carried in plasma by high‐density lipoprotein (HDL)‐associated apolipoprotein M (apoM) and by albumin. In sepsis, the protein and lipid composition of HDL changes dramatically. The aim of this study was to evaluate changes in S1P and its carrier protein apoM during sepsis. For this purpose, plasma samples from both human sepsis patients and from an experimental Escherichia coli sepsis model in baboons were used. In the human sepsis cohort, previously studied for apoM, plasma demonstrated disease‐severity correlated decreased S1P levels, the profile mimicking that of plasma apoM. In the baboons, a similar disease‐severity dependent decrease in plasma levels of S1P and apoM was observed. In the lethal E. coli baboon sepsis, S1P decreased already within 6–8 hrs, whereas the apoM decrease was seen later at 12–24 hrs. Gel filtration chromatography of plasma from severe human or baboon sepsis on Superose 6 demonstrated an almost complete loss of S1P and apoM in the HDL fractions. S1P plasma concentrations correlated with the platelet count but not with erythrocytes or white blood cells. The liver mRNA levels of apoM and apoA1 decreased strongly upon sepsis induction and after 12 hr both were almost completely lost. In conclusion, during septic challenge, the plasma levels of S1P drop to very low levels. Moreover, the liver synthesis of apoM decreases severely and the plasma levels of apoM are reduced. Possibly, the decrease in S1P contributes to the decreased endothelial barrier function observed in sepsis.
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Affiliation(s)
- Cecilia Frej
- Department of Translational Medicine, Division of Clinical Chemistry, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Adam Linder
- Department of Clinical Sciences, Division of Infection Medicine, Lund University, Skåne University Hospital, Lund, Sweden
| | - Kaisa E Happonen
- Department of Translational Medicine, Division of Clinical Chemistry, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Fletcher B Taylor
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Florea Lupu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Björn Dahlbäck
- Department of Translational Medicine, Division of Clinical Chemistry, Skåne University Hospital, Lund University, Malmö, Sweden
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Wang Y, Bahng JH, Che Q, Han J, Kotov NA. Anomalously Fast Diffusion of Targeted Carbon Nanotubes in Cellular Spheroids. ACS NANO 2015; 9:8231-8. [PMID: 26181892 PMCID: PMC11135955 DOI: 10.1021/acsnano.5b02595] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Understanding transport of carbon nanotubes (CNTs) and other nanocarriers within tissues is essential for biomedical imaging and drug delivery using these carriers. Compared to traditional cell cultures in animal studies, three-dimensional tissue replicas approach the complexity of the actual organs and enable high temporal and spatial resolution of the carrier permeation. We investigated diffusional transport of CNTs in highly uniform spheroids of hepatocellular carcinoma and found that apparent diffusion coefficients of CNTs in these tissue replicas are anomalously high and comparable to diffusion rates of similarly charged molecules with molecular weights 10000× lower. Moreover, diffusivity of CNTs in tissues is enhanced after functionalization with transforming growth factor β1. This unexpected trend contradicts predictions of the Stokes-Einstein equation and previously obtained empirical dependences of diffusivity on molecular mass for permeants in gas, liquid, solid or gel. It is attributed to the planar diffusion (gliding) of CNTs along cellular membranes reducing effective dimensionality of diffusional space. These findings indicate that nanotubes and potentially similar nanostructures are capable of fast and deep permeation into the tissue, which is often difficult to realize with anticancer agents.
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Affiliation(s)
- Yichun Wang
- Department of Biomedical Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, Michigan 48109, United States
| | - Joong Hwan Bahng
- Department of Biomedical Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, Michigan 48109, United States
| | - Quantong Che
- Department of Chemical Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
| | - Jishu Han
- Department of Chemical Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
| | - Nicholas A. Kotov
- Department of Biomedical Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
- Department of Chemical Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
- Department of Material Science & Engineering, University of Michigan, 3074 H.H. Dow Building, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, Michigan 48109, United States
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10
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HUANG LIZHU, GAO JIALIN, PU CHUN, ZHANG PUHONG, WANG LIZHUO, FENG GANG, ZHANG YAO. Apolipoprotein M: Research progress, regulation and metabolic functions (Review). Mol Med Rep 2015; 12:1617-24. [DOI: 10.3892/mmr.2015.3658] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 03/16/2015] [Indexed: 11/06/2022] Open
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11
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Yu Y, Luo GH, Zhang J, Jiang H, Wei J, Shi YP, Zhang XY, Xu N. Increased mRNA levels of apolipoprotein M and apolipoprotein AI in the placental tissues with fetal macrosomia. Arch Gynecol Obstet 2014; 291:299-303. [PMID: 25194312 DOI: 10.1007/s00404-014-3441-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/26/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE The present study examined mRNA levels of apolipoprotein M (apoM) and apolipoprotein AI (apoAI) in the term placental tissues obtained from 37 women with normal birth weight neonates and from 37 women with macrosomic neonates (birth body weight ≥4,000 g), and further discussed possible clinical significance of these observations. METHODS The mRNA levels of apoM and apoAI in the placental tissues were determined by the real time RT-PCR, which demonstrated that both apoM and apoAI mRNA levels were significantly higher in the placentas from macrosomia than those from normal birth. Moreover, we analyzed the overexpressions of apoM and apoAI with the clinical data. Meanwhile we examined several known risk factors of macrosomia including the mRNA levels of insulin-like growth factor I (IGF-I), IGF-II, insulin-like growth factor I receptor (IGF-IR) and IGF-IIR. RESULTS It demonstrated that apoM expression was significantly positively correlated to the placental weight, fetal birth weight, pregestational body mass index (BMI), weight gain during pregnancy, maternal weight, maternal BMI and the mRNA levels of IGF-IR as well as IGF-IIR. The apoAI mRNA level was statistically significantly correlated to the placental weight, fetal birth weight, IGF-I and IGF-IR mRNA levels. CONCLUSIONS Binary logistic regression analysis suggested that both apoM and apoAI mRNA may considered as independent risk factors for macrosomia. The clinical significance needs further investigation.
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Affiliation(s)
- Yang Yu
- Comprehensive Laboratory, Third Affiliated Hospital, Soochow University, Jiangsu, 213003, Changzhou, People's Republic of China,
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12
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Xie P, Liu B, Chen R, Yang B, Dong J, Rong L. Comparative analysis of serum proteomes: Identification of proteins associated with sciatica due to lumbar intervertebral disc herniation. Biomed Rep 2014; 2:693-698. [PMID: 25054013 DOI: 10.3892/br.2014.295] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 05/19/2014] [Indexed: 11/05/2022] Open
Abstract
Lumbar intervertebral disc herniation (LDH) is one of the most common orthopedic conditions that can cause lower back pain and sciatica. However, the pathogenesis of LDH is poorly understood. The aim of the present study was to use proteomic analysis of blood samples to establish whether there are serum proteins associated with LDH, which may be useful in elucidating LDH pathogenesis. The ultimate aim was to develop a simple technique for the diagnosis of LDH based on the blood samples of patients with sciatica. The study used comparative analysis of serum proteomes associated with sciatica due to LDH. A total of 30 LDH patients with sciatica, receiving treatment between August and December 2007, were selected as the experimental group (or LDH group). A total of 2 ml of blood was obtained from each of the 30 patients in the LDH group and from 30 healthy volunteers, who constituted the control group. Two-dimensional electrophoresis of the blood samples was conducted, distinct protein spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and proteins associated with LDH were detected. An enzyme-linked immunosorbent assay (ELISA) was developed to screen for the LDH proteins and was tested on the sera of a second test and control group that included 10 patients with LDH and 10 healthy subjects, respectively. Based on signal intensity, the expression levels of 6 proteins on the dielectrophoretogram were found to be significantly associated with LDH. The identities of the LDH proteins were upregulated apolipoprotein-L1 (APO-L1) and two types of serum albumin precursors, and downregulated apolipoprotein M (APO-M), tetranectin (TN) and immunoglobulin light chain (IGL). Further ELISA experiments confirmed that there were increased serum levels of 4 out of the 6 proteins in patients with sciatica due to LDH, which was statistically different compared to the healthy subjects. In conclusion, these results suggest that serum APO-L1, TN, APO-M and IGL may serve as LDH biomarkers.
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Affiliation(s)
- Peigen Xie
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Bin Liu
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Ruiqiang Chen
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Bu Yang
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Jianwen Dong
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Limin Rong
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
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Urinary apolipoprotein M could be used as a biomarker of acute renal injury: an ischemia-reperfusion injury model of kidney in rat. Transplant Proc 2014; 45:2476-9. [PMID: 23953565 DOI: 10.1016/j.transproceed.2013.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 02/20/2013] [Accepted: 04/23/2013] [Indexed: 01/22/2023]
Abstract
BACKGROUND It has been well documented that apolipoprotein M (apoM) is principally expressed in hepatocytes as well as renal tubular epithelial cells. The importance of apoM in the kidney is unknown. In the present study we examined urinary any apoM after short-term ischemia-reperfusion injury (IRI) of kidney in a rat model. METHODS The kidneys of 11 male Sprague-Dawley rats were rendered ischemic for 45 minutes followed by different intervals of reperfusion. Serum and urine apoM concentrations were determined using a dot-blot analysis with specific rabbit anti-human apoM antibodies that cross-react with rat apoM. Serum concentrations of blood urea nitrogen (BUN) and creatinine (Cr) were determined using standard clinical automated analyses. RESULTS BUN was significantly elevated after 45 minutes of ischemia followed by 24 hours of reperfusion; serum Cr concentrations were also significantly increased at 6 and 24 hours of reperfusion. Interestingly, similar to BUN and Cr, serum apoM concentrations were significantly increased after ischemia for 45 minutes alone and after 2 hours of reperfusion. Urinary apoM concentrations were obviously increased after 2 h as well as 6 hours of reperfusion. CONCLUSION apoM showed characteristics of an acute-phase reactive protein; its occurrence in urine may be considered to be a biomarker of acute renal injury.
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Huang Y, Liu Y, Jiang L, Sun R, Zhang H, Liu R, Xu N. Apolipoprotein m (APOM) levels and APOM rs805297 G/T polymorphism are associated with increased risk of rheumatoid arthritis. Joint Bone Spine 2014; 81:32-6. [DOI: 10.1016/j.jbspin.2013.03.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 03/20/2013] [Indexed: 01/22/2023]
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Dihydrotestosterone regulating apolipoprotein M expression mediates via protein kinase C in HepG2 cells. Lipids Health Dis 2012; 11:168. [PMID: 23216709 PMCID: PMC3543304 DOI: 10.1186/1476-511x-11-168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 11/20/2012] [Indexed: 11/14/2022] Open
Abstract
Background Administration of androgens decreases plasma concentrations of high-density lipid cholesterol (HDL-C). However, the mechanisms by which androgens mediate lipid metabolism remain unknown. This present study used HepG2 cell cultures and ovariectomized C57BL/6 J mice to determine whether apolipoprotein M (ApoM), a constituent of HDL, was affected by dihydrotestosterone (DHT). Methods HepG2 cells were cultured in the presence of either DHT, agonist of protein kinase C (PKC), phorbol-12-myristate-13-acetate (PMA), blocker of androgen receptor flutamide together with different concentrations of DHT, or DHT together with staurosporine at different concentrations for 24 hrs. Ovariectomized C57BL/6 J mice were treated with DHT or vehicle for 7d or 14d and the levels of plasma ApoM and livers ApoM mRNA were measured. The mRNA levels of ApoM, ApoAI were determined by real-time RT-PCR. ApoM and ApoAI were determined by western blotting analysis. Results Addition of DHT to cell culture medium selectively down-regulated ApoM mRNA expression and ApoM secretion in a dose-dependent manner. At 10 nM DHT, the ApoM mRNA levels were about 20% lower than in untreated cells and about 40% lower at 1000 nM DHT than in the control cells. The secretion of ApoM into the medium was reduced to a similar extent. The inhibitory effect of DHT on ApoM secretion was not blocked by the classical androgen receptor blocker flutamide but by an antagonist of PKC, Staurosporine. Agonist of PKC, PMA, also reduced ApoM. At 0.5 μM PMA, the ApoM mRNA levels and the secretion of ApoM into the medium were about 30% lower than in the control cells. The mRNA expression levels and secretion of another HDL-associated apolipoprotein AI (ApoAI) were not affected by DHT. The levels of plasma ApoM and liver ApoM mRNA of DHT-treated C57BL/6 J mice were lower than those of vehicle-treated mice. Conclusions DHT directly and selectively down-regulated the level of ApoM mRNA and the secretion of ApoM by protein kinase C but independently of the classical androgen receptor.
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Estrogen upregulates hepatic apolipoprotein M expression via the estrogen receptor. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:1146-51. [PMID: 21816233 DOI: 10.1016/j.bbalip.2011.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 07/05/2011] [Accepted: 07/07/2011] [Indexed: 11/23/2022]
Abstract
Apolipoprotein M (apoM) is present predominantly in high-density lipoprotein (HDL) in human plasma, thus possibly involved in the regulation of HDL metabolism and the process of atherosclerosis. Although estrogen replacement therapy increases serum levels of apoAI and HDL, it does not seem to reduce the cardiovascular risk in postmenopausal women. Therefore, we investigated the effects of estrogen on apoM expression in vitro and in vivo. HepG2 cells were incubated with different concentrations of estrogen with or without the estrogen receptor antagonist, fulvestrant, and apoM expression in the cells was determined. Hepatic apoM expression and serum levels of apoM were also determined in normal and in ovariectomized rats treated with either placebo or estradiol benzoate, using sham operated rats as controls. Estrogen significantly increased mRNA levels of apoM and apoAI in HepG2 cell cultures in a dose- and time-dependent manner; the upregulation of both apolipoproteins was fully abolished by addition of estrogen receptor antagonist. In normal rats, estrogen treatment led to an increase in plasma lipid levels including HDL cholesterol, a marked upregulation of apoM mRNA and a significant increase in serum levels of apoM. The same pattern of regulation was found in ovariectomized rats treated with estrogen. Thus, estrogen upregulates apoM expression both in vivo and in vitro by mechanism(s) involving the estrogen receptor.
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Zhang X, Mao S, Luo G, Wei J, Berggren-Söderlund M, Nilsson-Ehle P, Xu N. Effects of simvastatin on apolipoprotein M in vivo and in vitro. Lipids Health Dis 2011; 10:112. [PMID: 21729290 PMCID: PMC3141548 DOI: 10.1186/1476-511x-10-112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/05/2011] [Indexed: 12/12/2022] Open
Abstract
Objective To investigate effects of lipid lowering drug, simvastatin, on apolipoprotein M expression in the hyperlipidemic mice and in hepatic cell line, HepG2 cells. Methods Swiss male mice were randomly divided into the high fat group and control group, and were intragastrically fed with 0.9% saline (control group) or lipid emulsion (high fat group) at the daily dosage of 15 ml/kg body weight, respectively. After 8 weeks feeding, the hyperlipidemic model was successfully induced and these hyperlipidemic mice were then randomly divided into three experimental groups: vehicle control group, high-dose simvastatin-treated group (100 mg/kg body weight), and low-dose simvastatin-treated group (10 mg/kg body weight). Mice were dosed daily for 6 weeks of simvastatin before mice were sacrificed for determining serum lipid profile and apoM protein levels that was determined by using dot blotting analysis. Effects of simvastatin on apoM mRNA expression in the HepG2 cells were determined by real-time RT-PCR. Results Comparing to high fat model mice without simvastatin treatment, 100 mg/kg simvastatin could significantly increase serum total cholesterol (P < 0.05). Serum apoM levels, in all mice, were significantly lower in the mice at the age of 26 weeks than the mice at 12 weeks old (P < 0.05), which indicated that serum apoM levels were significantly correlated to the mice age. It demonstrated also that treatment of simvastatin did not influence serum apoM levels in these mouse model, although serum apoM levels were increased by about 13% in the 10 mg/kg simvastatin group than in the vehicle control group without simvastatin. In HepG2 cell cultures, simvastatin could significantly decrease apoM mRNA levels with dose- and time-dependent manners. At 10 μM simvastatin treatment, apoM mRNA decreased by 52% compared to the controls. Conclusion The present study suggested that simvastatin, in vivo, had no effect on apoM levels in the hyperlipidemic mouse model. ApoM serum levels in mice were significantly correlated to the animal's age, whereas in cell cultures simvastatin does inhibit apoM expression in the HepG2 cells. The mechanism behind it is not known yet.
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Affiliation(s)
- Xiaoying Zhang
- Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lund University, S-221 85 Lund, Sweden
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Association of apolipoprotein M gene polymorphisms with ischemic stroke in a Han Chinese population. J Mol Neurosci 2010; 43:370-5. [PMID: 20872094 DOI: 10.1007/s12031-010-9453-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 09/15/2010] [Indexed: 02/03/2023]
Abstract
The apolipoprotein M (ApoM) gene is critical in the formation of pre-β-high-density lipoprotein (HDL) and cholesterol efflux to HDL. In this case and control study, 314 ischemic stroke patients and 389 healthy controls were analyzed for three ApoM gene single-nucleotide polymorphisms (SNPs), i.e., C-1065A, T-855C, and T-778C, using a SNaPshot Multiplex sequencing assay. The genotype and allele frequencies of the T-855C were similar in both ischemic stroke patients and the controls. But the frequency of the TC genotype, the C allele of T-778C, and the A allele of the C-1065A SNPs in ischemic stroke patients was significantly higher than that of the healthy controls. After adjusting for confounding risk factors (such as hypertension, diabetes, tobacco smoking, and alcohol consumption), the ApoM gene TC genotype, C allele of T-778C, and A allele of C-1065A were associated with a risk of ischemic stroke. Moreover, plasma levels of total cholesterol were significantly higher in patients with CC or CT genotypes of T-778C than those with TT genotype in the controls. The current data demonstrated that ApoM T-778 C and C-1065A SNPs were associated with increased risk of ischemic stroke in this Han Chinese population.
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Luo G, Zhang X, Mu Q, Chen L, Zheng L, Wei J, Berggren-Söderlund M, Nilsson-Ehle P, Xu N. Expression and localization of apolipoprotein M in human colorectal tissues. Lipids Health Dis 2010; 9:102. [PMID: 20846402 PMCID: PMC2945960 DOI: 10.1186/1476-511x-9-102] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 09/16/2010] [Indexed: 01/29/2023] Open
Abstract
Background It has been well documented that apolipoprotein M (apoM) is principally expressed in the liver and kidney. However we found that there was weak apoM expression in other tissues or organs too, which could not be ignored. In the present study, we therefore examined apoM expression in human colorectal tissues including cancer tissues, cancer adjacent normal tissues, polyp tissues and normal mucosa as well as inflammatory mucosa. Methods Tissue samples were collected from patients who underwent surgical resection or endoscopic examination. ApoM mRNA levels were determined by the real-time RT-PCR and apoM protein mass were examined by the immunohistochemistry. Results ApoM protein can be detected in all colorectal tissues. However, apoM protein mass were significantly lower in the cancer tissues than its matched adjacent normal tissues, polyp tissues, normal mucosa and inflammatory mucosa. In parallel, apoM mRNA levels in the colorectal cancer tissues (0.0536 ± 0.0131) were also significantly lower than those in their adjacent normal tissues (0.1907 ± 0.0563) (P = 0.033). Interestingly, apoM mRNA levels in colorectal cancer tissues were statistic significant higher in the patients with lymph node metastasis than the patients without lymph node metastasis (P = 0.008). Patients under Dukes' C and D stages had much higher apoM mRNA levels than patients under Dukes' A and B stages (P = 0.034). Conclusion It is concluded that apoM could also be expressed in human colorectal tissues besides liver and kidney. ApoM mRNA levels in the colorectal cancer tissues were significantly increased in the patients with lymph node metastasis. Whether increased apoM expression in the patients with lymph node metastasis being related to patients' prognosis and the physiopathological importance of apoM expression in colorectal tissues need further investigation.
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Affiliation(s)
- Guanghua Luo
- Comprehensive Laboratory, Third Affiliated Hospital, Suzhou University, Changzhou, China
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20
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Pan G, Fu Y, Zuo B, Ren Z, Xu D, Lei M, Zheng R, Xiong YZ. Molecular characterization, expression profile and association analysis with fat deposition traits of the porcine APOM gene. Mol Biol Rep 2009; 37:1363-71. [PMID: 19326253 DOI: 10.1007/s11033-009-9518-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 03/17/2009] [Indexed: 10/21/2022]
Abstract
Apolipoprotein M (APOM), a novel apolipoprotein presented mostly in high-density lipoprotein (HDL) in plasma, is involved in lipid and lipoprotein metabolism. Through comparative mapping, we have mapped this gene to SSC7 p1.1 in which many QTLs affecting fat deposition traits have been reported. As a candidate gene for fat deposition traits, in this study, we obtained the 742-bp mRNA sequence of porcine APOM including the full coding region and encoding a protein of 188 amino acids. The sequence was deposited into the GenBank under the accession no. DQ329240. Semi-quantitative RT-PCR results showed that the porcine APOM gene is expressed predominantly in liver and kidney tissue. The genomic sequence of this gene which contains six exons and five introns, is 3,621 bp in length (DQ272488). Bioinformatic analysis of the 5' regulatory region has revealed that classical TATA-box element and species conserved Hepatocyte nuclear factor-1a (HNF-1alpha) biding site were represented in this region. A G2289C single nucleotide polymorphism (SNP) in the intron 2 of porcine APOM gene detected as an Eco130I PCR-restriction fragment length polymorphism (PCR-RFLP) showed allele frequency differences among three purebreds. Association of the genotypes with fat deposition traits showed that different genotypes of porcine APOM gene were significantly associated with leaf fat weight (P < 0.05), backfat thickness at shoulder (P < 0.05), backfat thickness at thorax-waist (P < 0.05), backfat thickness at buttock (P < 0.01) and average backfat thickness over shoulder, thorax-waist and buttock (P < 0.01).
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Affiliation(s)
- Gang Pan
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China
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Wu X, Niu N, Brismar K, Zhu X, Wang X, Efendic S, Du T, Liu Y, Gu HF, Liu Y. Apolipoprotein M promoter polymorphisms alter promoter activity and confer the susceptibility to the development of type 1 diabetes. Clin Biochem 2008; 42:17-21. [PMID: 19007767 DOI: 10.1016/j.clinbiochem.2008.10.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 10/10/2008] [Accepted: 10/11/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Apolipoprotein M plays an important role in the formation of prebeta-HDL and cholesterol efflux to HDL. In the present study, we investigate the potential association between the ApoM promoter polymorphisms and type 1 diabetes. DESIGN AND METHODS The study was conducted in Peking Union Medical College, Beijing, China and Karolinska Institutet, Stockholm, Sweden. Two populations, including 493 Han Chinese subjects (177 T1D patients/316 controls) and 225 Swedish (124/101), are enrolled in the present study. Three single nucleotide polymorphisms (SNP) C-1065A, T-855C and T-778C in the promoter region of the ApoM gene are genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) protocol. Promoter activity was measured by reporter gene assay. RESULTS SNP T-778C was strongly associated with T1D in both Han Chinese (p=0.002, OR=2.188, CI 95%=1.338-3.581) and Swedish (p=0.021, OR=2.865, CI 95%=1.128-7.278) populations. The luciferase activity of -778C promoter was 1.41 times as high as that of -778T promoter (9.90+/-1.92 vs. 7.04+/-0.76, p=0.001). CONCLUSIONS Allele C of SNP T-778C may increase promoter activity and confer the risk susceptibility to the development of T1D.
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Affiliation(s)
- Xiaopan Wu
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, 5 Dongdan 3 Tiao, Beijing 100005, PR China.
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Liver X receptor agonist downregulates hepatic apoM expression in vivo and in vitro. Biochem Biophys Res Commun 2008; 371:114-7. [PMID: 18413148 DOI: 10.1016/j.bbrc.2008.04.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 04/02/2008] [Indexed: 01/10/2023]
Abstract
It has been demonstrated that apolipoprotein M (apoM), a recently discovered HDL apolipoprotein, has antiatherosclerotic properties, which may be mediated by the enhancement of reversed cholesterol transportation and/or hepatic cholesterol catabolism. The detailed mechanisms are unknown yet. Liver X receptor (LXR) belongs to the nuclear receptor superfamily and is a ligand-activated transcription factor involved in the regulation of lipid metabolism and inflammation. Activation of LXR in the cell cultures results in an enhancement of cholesterol efflux to apoAI. In the present study, we investigated effects of the LXR agonist, T0901317 on hepatic apoM expression in vivo and in vitro. Serum apoM levels in mice given T0901317 at 10 mg or 100 mg/kg for 7 days were reduced by 12-17% (P<0.05). In HepG2 cell cultures, apoM mRNA levels were significantly lower in presence of 25 microM T0901317 (37.1%) than in control cells (P<0.001). A similar reduction was found by the addition of 9-cis retinoic acid (RA). Twenty-five micromolar T0901317 together with 100 nM RA decreased apoM mRNA expression by 65% (P<0.001). Thus, the LXR agonist T0901317 significantly downregulates apoM mRNA expression in vivo and in vitro, which indicates that apoM is another novel target gene regulated by the LXR. The combination of RA and T0901317 showed additive effects, which suggests that apoM expression can be modulated by LXR/RXR pathway.
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Gazzana G, Borlak J. Mapping of the serum proteome of hepatocellular carcinoma induced by targeted overexpression of epidermal growth factor to liver cells of transgenic mice. J Proteome Res 2008; 7:928-37. [PMID: 18198842 DOI: 10.1021/pr070462c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Epidermal growth factor (EGF) is an important mitogen for hepatocytes. Its targeted overexpression induced hepatocellular carcinomas (HCC), as recently reported by us (Borlak et al. 2005). Early detection of disease is essential for successful therapy and overall survival. Here we describe our efforts in identifying serum biomarkers of liver cancer in a transgenic disease model that mimics effectively the consequence of exaggerated EGF signaling. We report a reference 2-DE map of mouse serum proteins. About 180 proteins were detected per gel and 130 proteins were identified by 2-DE-MALDI-MS analysis. We compared serum proteins of healthy nontransgenic and HCC tumor-bearing mice and identified 25 regulated proteins, of which n = 7 reached statistical significance ( p < 0.05). Furthermore, we identified several fragments of fibrinogens and of the alpha-2-macroglobulin to be disease-associated. We also found immunoglobulins to be repressed or absent in serum samples of tumor-bearing mice, and this included, among others, the Ig K and L class. In contrast, amyloid component P and apolipoprotein M were highly significantly increased by 10- and 8-fold, respectively, in serum samples of HCC mice. Overall, our findings provide a rationale for further clinical evaluation of the herein identified biomarker candidates.
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Affiliation(s)
- Giuseppe Gazzana
- Department of Drug Research and Medical Biotechnology, Fraunhofer Institute of Toxicology and Experimental Medicine, Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany
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Jiao GQ, Yuan ZX, Xue YS, Yang CJ, Lu CB, Lu ZQ, Xiao MD. A prospective evaluation of apolipoprotein M gene T-778C polymorphism in relation to coronary artery disease in Han Chinese. Clin Biochem 2007; 40:1108-12. [PMID: 17674965 DOI: 10.1016/j.clinbiochem.2007.04.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 04/10/2007] [Accepted: 04/30/2007] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Apolipoprotein M (apoM) is important for the formation of pre-beta-high-density lipoprotein (HDL) and cholesterol efflux in macrophages. It is demonstrated that single-nucleotide polymorphism (SNP) T-778C of apoM gene is related to type 2 diabetes in Han Chinese. In the present study, we investigated the possible association of apoM polymorphism in relation to coronary artery disease (CAD) in Han Chinese. DESIGN AND METHODS This case-controlled study consisted of 118 CAD patients who were diagnosed angiographically to have at least 30% stenosis, and 255 unrelated subjects who were used as control. ApoM gene polymorphism in the proximal promoter region was analyzed by PCR-RFLP and serum lipid levels were also measured. RESULTS It is indicated that CAD patients had increased frequency of C allele on apoM T-778C compared to the controls (14.8% vs. 6.9%, P=0.0008). Multivariable logistic regression analysis indicated that odds ratios (ORs) for all subjects with apoM CC+CT genotypes and C allele were 1.9 (95% CI=1.1-2.9, P<0.0001) and 1.9 (95% CI=1.3-3.2, P<0.0001), respectively. The plasma total cholesterol (TC) levels were significantly higher in individuals with CC or CT genotype than those with TT genotype in both CAD patients and controls. CONCLUSIONS The present findings suggest that the C allele at nucleotide -778 in the apoM gene is a risk factor for genetic susceptibility to CAD and is also associated with TC levels in Han Chinese.
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Affiliation(s)
- Guo-qing Jiao
- Department of Cardiovascular Surgery, Affiliated Shanghai 1st People's Hospital, Shanghai Jiaotong University, Hongkou 85 Wujin Road, Shanghai 200080, PR China
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Zhang X, Jiang B, Luo G, Nilsson-Ehle P, Xu N. Hyperglycemia down-regulates apolipoprotein M expression in vivo and in vitro. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:879-82. [PMID: 17556016 DOI: 10.1016/j.bbalip.2007.04.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 04/20/2007] [Accepted: 04/30/2007] [Indexed: 10/23/2022]
Abstract
Diabetes is associated with low concentrations of apoM in plasma. In db/db mice, ob/ob mice as well as in the alloxan-induced diabetic mouse, the low apoM levels are paralleled by decreased expression of the apoM gene. In the latter model, insulin substitution tended to reverse the low apoM expression. It is not known whether the impairment in apoM expression can be ascribed to hyperglycemia, insulin deficiency or insulin resistance. In the present study, we investigated apoM levels and expression in rats rendered hyperglycemic by short-term glucose infusion. As expected, serum insulin concentrations rose moderately during the infusions. Serum apoM concentrations and hepatic apoM mRNA levels were significantly reduced in the hyperglycemic rats, indicating that the low expression of apoM in these diabetic models can be ascribed to hyperglycemia rather than to insulin deficiency or insulin resistance. However, in HepG2 cells both glucose and insulin markedly inhibited apoM expression these effects were additive. Thus, the possible effects of insulin in vivo seem to be mediated indirectly.
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Affiliation(s)
- Xiaoying Zhang
- Comprehensive Laboratory, The Third Affiliated Hospital, Suzhou University, Changzhou 213003, China
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Huang XS, Zhao SP, Hu M, Luo YP. Apolipoprotein M likely extends its anti-atherogenesis via anti-inflammation. Med Hypotheses 2007; 69:136-40. [PMID: 17218068 DOI: 10.1016/j.mehy.2006.10.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 10/24/2006] [Indexed: 10/23/2022]
Abstract
Apolipoprotein M (apoM), a novel human apolipoprotein recently discovered, predominantly presents in high density lipoprotein (HDL) in plasma, exclusively expressed in liver and in kidney. The present data demonstrated apoM protects against atherosclerosis (AS) primarily via partaking in prebeta-HDL formation and promoting cholesterol efflux to HDL. However, this lipid-metabolism-associated pathway seems unlikely responsible for all atheroprotective effects of apoM. Notably, the human apoM gene is just located in the major histocompatibility complex class III region (MHC-III) on chromosome 6, many genes in this region are related to the immune and inflammatory response. Furthermore, apoM has been documented to link with some inflammatory factors including platelet activating factor (PAF) and leptin. These evidences indicate that apoM may be involved in inflammatory activities in vivo and the potential immuno- and inflam-reactive property of apoM may contribute to the anti-inflammatory function of HDL, as generally acknowledged as an important atheroprotective mechanism of HDL.
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Affiliation(s)
- Xian-sheng Huang
- Department of Cardiology, The Second Xiangya Hospital of Central South University, No. 139, Renmin Zhonglu, Changsha, Hunan 410011, PR China.
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Niu N, Zhu X, Liu Y, Du T, Wang X, Chen D, Sun B, Gu HF, Liu Y. Single nucleotide polymorphisms in the proximal promoter region of apolipoprotein M gene (apoM) confer the susceptibility to development of type 2 diabetes in Han Chinese. Diabetes Metab Res Rev 2007; 23:21-5. [PMID: 16572495 DOI: 10.1002/dmrr.641] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Dyslipidemia correlating to insulin resistance is one of the key features in type 2 diabetes (T2D). Recent studies have demonstrated that apolipoprotein M (apoM) is important for the formation of prebeta-high-density lipoprotein (HDL) and cholesterol (CHO) efflux in macrophages to HDL. In the present study, we investigated the potential association of apoM genetic variation with the development of T2D. METHODS Single nucleotide polymorphisms (SNPs) C-1065A, T-855C and T-778C in the proximal promoter region of apoM gene were validated to represent in Han Chinese. Further genotyping experiments in 170 T2D patients and 156 non-diabetic control subjects were performed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS Single marker analysis for SNP T-778C indicated that T2D patients had increased frequency of C allele in comparison with non-diabetic controls (10.6% versus 5.8%, P = 0.026, OR = 1.934). In non-diabetic controls, the carriers with CT and CC genotypes had higher plasma CHO (221.7 versus 204.2 mg/dL, P = 0.033) and fasting plasma glucose (FPG) (92.6 versus 89.7 mg/dL, P = 0.041) levels than the subjects with TT genotype. Further analysis with adjustment for age, BMI, SBP, DBP, CHO and TG demonstrated that this SNP was strongly associated with T2D (P = 0.013, OR = 2.287). Haplotype analysis for those three SNPs, however, indicated that the common haplotypes were less informative than studying the role of the T-778C variant independently of the haplotype context. CONCLUSION The present study provided the first evidence that SNP T-778C in the proximal promoter region of apoM gene was associated with the levels of plasma CHO and FPG and also conferred the risk in the development of T2D among Han Chinese.
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Affiliation(s)
- Nifang Niu
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, PR China
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Xu X, Ye Q, Xu N, He X, Luo G, Zhang X, Zhu J, Zhang Y, Nilsson-Ehle P. Effects of Ischemia-Reperfusion Injury on Apolipoprotein M Expression in the Liver. Transplant Proc 2006; 38:2769-73. [PMID: 17112825 DOI: 10.1016/j.transproceed.2006.08.133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Indexed: 10/23/2022]
Abstract
The present study investigated the expression pattern of apolipoprotein M (apoM) mRNA in a rat model of hepatic ischemia-reperfusion injury (IRI). Animals were ischemic for 1 hour followed by various reperfusion times. As expected, serum alanine aminotransferase levels were significantly increased under IRI, which indicated the severity of liver injury. Hepatic mRNA levels of HSP70, which is the most common characterized protein within the family of heat-shock proteins (HSP), were significantly increased after 0.5 to 3 hours of IRI. Plasma C-reactive protein, high-density lipoprotein-cholesterol, and lipoprotein (a) levels were significantly increased after 1-hour ischemia followed by 0.5 to 3 hours of reperfusion. Interestingly, similar to HSP70, apoM mRNA levels in the liver were gradually increased after 0.5 to 3 hours of IRI, whereas it returned to a lower level after 6 or 24 hours of IRI, which indicated that hepatic apoM expression was significantly influenced by the acute phase of IRI. However, plasma apoM levels were not increased in parallel, even slightly decreasing after 0.5 or 1 hour of IRI. We concluded that apoM mRNA expression pattern, like HSP70, in the liver showed rapid, significant changes during hepatic local IRI.
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Affiliation(s)
- X Xu
- Research Institute of Organ Transplantation, The Affiliated TongJi Hospital of Huazhong University of Science and Technology, Wuhan, China
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Abstract
PURPOSE OF REVIEW Apolipoprotein M is a recently described apolipoprotein predominantly associated with high-density lipoprotein, but also found in chylomicrons, very low-density lipoproteins, and low-density lipoprotein. The purpose is to review recent information on the unusual structural properties of apolipoprotein M and its possible role in formation of pre-beta high-density lipoprotein and reverse cholesterol metabolism. RECENT FINDINGS Apolipoprotein M is a lipocalin having a coffee filter-like structure with a hydrophobic ligand-binding pocket. Mature apolipoprotein M retains its signal peptide, which serves as a hydrophobic anchor. In mice, silencing of expression in the liver with siRNA led to disappearance of pre-beta high-density lipoprotein and appearance of unusually large high-density lipoproteins. This suggests that apolipoprotein M is important for the formation of pre-beta high-density lipoprotein and reverse cholesterol transport. In accordance with this idea, hepatic overexpression of apolipoprotein M with an adenovirus in low-density lipoprotein-receptor deficient mice led to an approximately 70% reduction of atherosclerosis. In addition to the liver, apolipoprotein M is also expressed in the kidney. Kidney-derived apolipoprotein M binds to megalin, a member of the low-density lipoprotein-receptor family, which interacts with many lipocalins in renal tubuli. Apolipoprotein M is excreted in the urine of mice with a kidney-specific megalin deficiency but not in the urine of normal mice, suggesting megalin-mediated uptake of apolipoprotein M in the tubular epithelium of normal mice. SUMMARY Apolipoprotein M is a novel apolipoprotein with unusual structural features that appears to play important roles in high-density lipoprotein metabolism and prevention of atherosclerosis.
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Affiliation(s)
- Björn Dahlbäck
- Department of Laboratory Medicine, Clinical Chemistry, Lund University, Wallenberg Laboratory, University Hospital, Malmo, Sweden.
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30
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Abstract
PURPOSE OF REVIEW The goal of this review is to provide an update on the most recent and relevant findings in the area of genotype-phenotype associations as well as the relationships between genetic factors and cardiovascular disease risk markers and events. In addition, emphasis will be placed on the methodological problems associated with studying the genetics of complex disorders, specifically cardiovascular diseases. RECENT FINDINGS Genes associated with cardiovascular disease predisposition have been examined, including traditional cardiovascular disease candidate genes, such as ACE, AGT, eNOS, PON and MTHFR, new loci that have recently been added to the growing list of cardiovascular disease candidate genes (i.e. MEF2A, ALOX5, LTA, APOM, PDE4D), and genes that have been shown to be at the intersection of several age-related disorders through interaction with one another or with environmental factors (i.e. APOA5, APOE, PPARgamma, LPL and LIPC). SUMMARY During the last year, tremendous effort has been made in elucidating new genes associated with cardiovascular disease predisposition. For the most part, however, major breakthroughs have not been made, primarily due to the poor replication of results among studies, as a consequence of poor experimental design. Nevertheless, we have increased our understanding of the complexity of cardiovascular disease and the relevance of gene-environment interactions as the ultimate drivers of the individual predisposition to the disease. It is essential, therefore, that present and future genetic studies in this area take into consideration the inclusion of high-quality environmental data in the analytical process to test the clinical usefulness of a genetic marker as a risk predictor.
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Xu N, Nilsson-Ehle P, Ahrén B. Suppression of apolipoprotein M expression and secretion in alloxan-diabetic mouse: Partial reversal by insulin. Biochem Biophys Res Commun 2006; 342:1174-7. [PMID: 16516154 DOI: 10.1016/j.bbrc.2006.02.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 02/06/2006] [Indexed: 11/18/2022]
Abstract
We previously reported that apolipoprotein M (apoM) expression is reduced in ob/ob mice. Whether such a reduction is specific for this model or is a more general phenomenon in diabetes models is not known. In the present study, we therefore investigated apoM expression and secretion in NMRI mice rendered diabetes through administration of alloxan (120 mg/kg). Plasma glucose levels were markedly increased and plasma insulin levels markedly reduced at 3 days after alloxan. At the same time, that plasma apoM concentrations were decreased by 70%, apoM mRNA levels in liver was decreased by 40%, and apoM mRNA in kidney was decreased by 20% in alloxan-treated mice compared to saline-injected controls. Furthermore we found also that daily sc administration of insulin (5 IU/kg per day) increased plasma apoM levels, and apoM mRNA levels in liver and kidney. We therefore conclude that apoM is reduced in this diabetes model and that exogenous insulin administrations partially reverses the abnormal apoM expression. Based on these results, we suggest that insulin regulates apoM synthesis in vivo and, therefore, that the reduction of apoM expression is a general phenomenon in diabetes models.
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Affiliation(s)
- Ning Xu
- Division of Clinical Chemistry and Pharmacology, Institute of Laboratory Medicine, Lund University, Lund, S-221 85 Lund, Sweden.
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Luo G, Hurtig M, Zhang X, Nilsson-Ehle P, Xu N. Leptin inhibits apolipoprotein M transcription and secretion in human hepatoma cell line, HepG2 cells. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1734:198-202. [PMID: 15904876 DOI: 10.1016/j.bbalip.2005.02.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 01/20/2005] [Accepted: 02/17/2005] [Indexed: 11/27/2022]
Abstract
Apolipoprotein M (apoM) is a novel apolipoprotein presented mostly in high-density lipoprotein (HDL) in human plasma. Previously we have reported that both leptin and leptin receptor are essential for apoM expression in vivo. The expression of apoM is lower in the leptin deficient (ob/ob) mouse and leptin receptor deficient (db/db) mouse than in the normal mouse. In the present study, however, we demonstrated that supra-physiological concentrations of recombinant leptin significantly inhibited apoM transcription and secretion in the human hepatoma cell line, HepG2 cells. Both Northern blotting and real-time RT-PCR were applied into the analyses of apoM mRNA levels, and compatible data were obtained. The inhibitory effect of leptin on apoM mRNA levels in HepG2 cells is dose dependent, i.e. 100 ng/mL of leptin decreased apoM mRNA levels by 30%, and 500 ng/mL of leptin decreased apoM mRNA levels about 50%. Even at a physiological concentration of leptin (10 ng/mL), apoM expression was decreased, and in parallel, the secretion of apoM into the medium was also decreased. Furthermore, we examined apoAI, apoB and apoE by Northern blotting analyses. The results demonstrated that leptin does not significantly influence the expressions of apoAI, apoB and apoE in HepC2 cells, suggesting that leptin has a specific regulatory effect on hepatic apoM transcription and secretion in vitro. The mechanism on the contradictory effects of leptin on apoM expression in vivo and in vitro needs further investigation.
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Affiliation(s)
- Guanghua Luo
- Laboratory of Molecular Medicine, The Third Affiliated Hospital, Suzhou University, Changzhou 213003, China
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Luo G, Zhang X, Nilsson-Ehle P, Xu N. Apolipoprotein M. Lipids Health Dis 2004; 3:21. [PMID: 15461812 PMCID: PMC523857 DOI: 10.1186/1476-511x-3-21] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Accepted: 10/04/2004] [Indexed: 11/24/2022] Open
Abstract
Apolipoprotein M (apoM) is a 26-kDa protein that is mainly associated with high-density lipoprotein (HDL) in human plasma, with a small proportion present in triglyceride-rich lipoproteins (TGRLP) and low-density lipoproteins (LDL). Human apoM gene is located in p21.31 on chromosome 6 (chromosome 17, in mouse). Human apoM cDNA (734 base pairs) encodes 188-amino acid residue-long protein. It belongs to lipocalin protein superfamily. Human tissue expression array study indicates that apoM is only expressed in liver and in kidney and small amounts are found in fetal liver and kidney. In situ apoM mRNA hybridization demonstrates that apoM is exclusively expressed in the hepatocytes and in the tubule epithelial cells in kidney. Expression of apoM could be regulated by platelet activating factor (PAF), transforming growth factors (TGF), insulin-like growth factor (IGF) and leptin in vivo and/or in vitro. It has been demonstrated that apoM expression is dramatically decreased in apoA-I deficient mouse. Hepatocyte nuclear factor-1α (HNF-1α) is an activator of apoM gene promoter. Deficiency of HNF-1α mouse shows lack of apoM expression. Mutations in HNF-1α (MODY3) have reduced serum apoM levels. Expression of apoM is significantly decreased in leptin deficient (ob/ob) mouse or leptin receptor deficient (db/db) mouse. ApoM concentration in plasma is positively correlated to leptin level in obese subjects. These may suggest that apoM is related to the initiation and progression of MODY3 and/or obesity.
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Affiliation(s)
- Guanghua Luo
- Department of Clinical Chemistry, Institute of Laboratory Medicine, University Hospital of Lund, S-221 85 Lund, Sweden
- Laboratory of Molecular Medicine, The Third Affiliated Hospital, Su Zhou University, Chang Zhou 213003, China
| | - Xiaoying Zhang
- Laboratory of Molecular Medicine, The Third Affiliated Hospital, Su Zhou University, Chang Zhou 213003, China
| | - Peter Nilsson-Ehle
- Department of Clinical Chemistry, Institute of Laboratory Medicine, University Hospital of Lund, S-221 85 Lund, Sweden
| | - Ning Xu
- Department of Clinical Chemistry, Institute of Laboratory Medicine, University Hospital of Lund, S-221 85 Lund, Sweden
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