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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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Makanai H, Nishihara T, Nishikawa M, Tanabe K. Hoechst-Modification on Oligodeoxynucleotides for Efficient Transport to the Cell Nucleus and Gene Regulation. Chembiochem 2024; 25:e202300645. [PMID: 37984902 DOI: 10.1002/cbic.202300645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 11/22/2023]
Abstract
Various artificial oligodeoxynucleotides (ODNs) that contribute to gene regulation have been developed and their diversity and multifunctionality have been demonstrated. However, few artificial ODNs are actively transported to the cell nucleus, despite the fact that gene regulation also takes place in both the cell nucleus and the cytoplasm. In this study, to prepare ODNs with the ability to accumulate in the cell nucleus, we introduced Hoechst molecules into ODNs that act as carriers of functional molecules to the cell nucleus (Hoe-ODNs). We synthesized Hoe-ODNs and confirmed that they bound strongly to DNA duplexes. When single-stranded Hoe-ODNs or double-stranded ODNs consisting of Hoe-ODNs and its complementary strand were administered into living cells, both ODNs were efficiently accumulated in the cell nucleus. In addition, antisense ODNs, which were tethered with Hoechst unit, were delivered into the cell nucleus and efficiently suppressed the expression of their target RNA. Thus, we constructed a delivery system that enables the transport of ODNs into cell nucleus.
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Affiliation(s)
- Hiroki Makanai
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Tatsuya Nishihara
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Makiya Nishikawa
- Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Kazuhito Tanabe
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
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Wei W, Chen Q, Liu M, Sheng Y, OuYang Q, Feng W, Yang X, Ding L, Su S, Zhang J, Fang L, Vidal-Puig A, Wang HY, Chen S. TRIM24 is an insulin-responsive regulator of P-bodies. Nat Commun 2022; 13:3972. [PMID: 35803934 PMCID: PMC9270398 DOI: 10.1038/s41467-022-31735-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 06/29/2022] [Indexed: 11/09/2022] Open
Abstract
Insulin is a potent inducer of mRNA transcription and translation, contributing to metabolic regulation. Insulin has also been suggested to regulate mRNA stability through the processing body (P-body) molecular machinery. However, whether and how insulin regulates mRNA stability via P-bodies is not clear. Here we show that the E3-ligase TRIM24 is a critical factor linking insulin signalling to P-bodies. Upon insulin stimulation, protein kinase B (PKB, also known as Akt) phosphorylates TRIM24 and stimulates its shuttling from the nucleus into the cytoplasm. TRIM24 interacts with several critical components of P-bodies in the cytoplasm, promoting their polyubiquitylation, which consequently stabilises Pparγ mRNA. Inactivation of TRIM24 E3-ligase activity or prevention of its phosphorylation via knockin mutations in mice promotes hepatic Pparγ degradation via P-bodies. Consequently, both knockin mutations alleviate hepatosteatosis in mice fed on a high-fat diet. Our results demonstrate the critical role of TRIM24 in linking insulin signalling to P-bodies and have therapeutic implications for the treatment of hepatosteatosis.
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Affiliation(s)
- Wen Wei
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
- Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Qiaoli Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
- Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Minjun Liu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
- Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Yang Sheng
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
- Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Qian OuYang
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Weikuan Feng
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Xinyu Yang
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Longfei Ding
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Shu Su
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Jingzi Zhang
- School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Lei Fang
- School of Medicine, Nanjing University, Nanjing, 210061, China
| | - Antonio Vidal-Puig
- TVP Lab, WT/MRC Institute of Metabolic Science, MRC Metabolic Diseases Unit - Metabolic Research Laboratories, University of Cambridge, Cambridge, UK
- Cambridge University Nanjing Centre of Technology and Innovation, Jiangbei Area, Nanjing, China
| | - Hong-Yu Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China.
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China.
- Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China.
| | - Shuai Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Endocrinology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, 210061, China.
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China.
- Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing, 210061, China.
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Stahel P, Xiao C, Nahmias A, Tian L, Lewis GF. Multi-organ Coordination of Lipoprotein Secretion by Hormones, Nutrients and Neural Networks. Endocr Rev 2021; 42:815-838. [PMID: 33743013 PMCID: PMC8599201 DOI: 10.1210/endrev/bnab008] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Indexed: 12/15/2022]
Abstract
Plasma triglyceride-rich lipoproteins (TRL), particularly atherogenic remnant lipoproteins, contribute to atherosclerotic cardiovascular disease. Hypertriglyceridemia may arise in part from hypersecretion of TRLs by the liver and intestine. Here we focus on the complex network of hormonal, nutritional, and neuronal interorgan communication that regulates secretion of TRLs and provide our perspective on the relative importance of these factors. Hormones and peptides originating from the pancreas (insulin, glucagon), gut [glucagon-like peptide 1 (GLP-1) and 2 (GLP-2), ghrelin, cholecystokinin (CCK), peptide YY], adipose tissue (leptin, adiponectin) and brain (GLP-1) modulate TRL secretion by receptor-mediated responses and indirectly via neural networks. In addition, the gut microbiome and bile acids influence lipoprotein secretion in humans and animal models. Several nutritional factors modulate hepatic lipoprotein secretion through effects on the central nervous system. Vagal afferent signaling from the gut to the brain and efferent signals from the brain to the liver and gut are modulated by hormonal and nutritional factors to influence TRL secretion. Some of these factors have been extensively studied and shown to have robust regulatory effects whereas others are "emerging" regulators, whose significance remains to be determined. The quantitative importance of these factors relative to one another and relative to the key regulatory role of lipid availability remains largely unknown. Our understanding of the complex interorgan regulation of TRL secretion is rapidly evolving to appreciate the extensive hormonal, nutritional, and neural signals emanating not only from gut and liver but also from the brain, pancreas, and adipose tissue.
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Affiliation(s)
- Priska Stahel
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Avital Nahmias
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lili Tian
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary Franklin Lewis
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Heeren J, Scheja L. Metabolic-associated fatty liver disease and lipoprotein metabolism. Mol Metab 2021; 50:101238. [PMID: 33892169 PMCID: PMC8324684 DOI: 10.1016/j.molmet.2021.101238] [Citation(s) in RCA: 210] [Impact Index Per Article: 70.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/01/2021] [Accepted: 04/15/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease, or as recently proposed 'metabolic-associated fatty liver disease' (MAFLD), is characterized by pathological accumulation of triglycerides and other lipids in hepatocytes. This common disease can progress from simple steatosis to steatohepatitis, and eventually end-stage liver diseases. MAFLD is closely related to disturbances in systemic energy metabolism, including insulin resistance and atherogenic dyslipidemia. SCOPE OF REVIEW The liver is the central organ in lipid metabolism by secreting very low density lipoproteins (VLDL) and, on the other hand, by internalizing fatty acids and lipoproteins. This review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of MAFLD. MAJOR CONCLUSIONS Liver steatosis in MAFLD is triggered by excessive hepatic triglyceride synthesis utilizing fatty acids derived from white adipose tissue (WAT), de novo lipogenesis (DNL) and endocytosed remnants of triglyceride-rich lipoproteins. In consequence of high hepatic lipid content, VLDL secretion is enhanced, which is the primary cause of complex dyslipidemia typical for subjects with MAFLD. Interventions reducing VLDL secretory capacity attenuate dyslipidemia while they exacerbate MAFLD, indicating that the balance of lipid storage versus secretion in hepatocytes is a critical parameter determining disease outcome. Proof of concept studies have shown that promoting lipid storage and energy combustion in adipose tissues reduces hepatic lipid load and thus ameliorates MAFLD. Moreover, hepatocellular triglyceride synthesis from DNL and WAT-derived fatty acids can be targeted to treat MAFLD. However, more research is needed to understand how individual transporters, enzymes, and their isoforms affect steatosis and dyslipidemia in vivo, and whether these two aspects of MAFLD can be selectively treated. Processing of cholesterol-enriched lipoproteins appears less important for steatosis. It may, however, modulate inflammation and consequently MAFLD progression.
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Affiliation(s)
- Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Ludger Scheja
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Hypertriglyceridemia and Other Plasma Lipid Profile Abnormalities among People Living with Diabetes Mellitus in Ethiopia: A Systematic Review and Meta-Analysis. BIOMED RESEARCH INTERNATIONAL 2021; 2021:7389076. [PMID: 34056001 PMCID: PMC8131138 DOI: 10.1155/2021/7389076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 03/11/2021] [Accepted: 04/30/2021] [Indexed: 11/17/2022]
Abstract
Background Dyslipidemia is one of the leading causes of cardiovascular complications in diabetes mellitus (DM) patients. Though it is a major public health problem in Ethiopia, there is no a nation-wide study to determine dyslipidemia among DM patients yet. Therefore, this systematic review and meta-analysis intended to estimate the prevalence of hypertriglyceridemia and other plasma lipid abnormalities among people living with DM in Ethiopia. Methods We systematically searched PubMed, Google Scholar, African Journals Online, Hinari, and direct Google. Studies conducted until May 9, 2020, that reports the prevalence of dyslipidemia among people living with DM were included. The DerSimonian and Laird random-effects model was used to determine the pooled prevalence of lipid profile abnormalities. Heterogeneity was checked using the I 2 statistic, whereas publication bias was tested by funnel plot and Egger's test. Besides, subgroup and sensitivity analyses were performed. Results We used 18 primary studies, including 4961 participants living with DM, which met the eligibility criteria for the meta-analysis of hypertriglyceridemia. The estimate of hypertriglyceridemia (≥150 mg/dl) was 48.15% (95% CI: 38.15-58.15, I 2 = 98.4%) after performing the main meta-analysis using the random-effects model. The subgroup analysis showed a higher pooled estimate of hypertriglyceridemia among T2DM (57.80% (95% CI: 50.50-65.10), I 2 = 92.5%), studies that used probability sampling technique (59.09% (95% CI: 43.58-74.59), I 2 = 98.6%, p < 0.001), and studies from primary data sources (51.43% (95% CI: 40.72-62.13), I 2 = 98.0%, p < 0.001). Moreover, the estimated pooled prevalence of the total plasma cholesterol (TC ≥ 200 mg/dl) was 34.08% (95% CI: 28.41-39.75, I 2 = 92.4%), LDL - C ≥ 100 mg/dl was 41.13% (95% CI: 27.15-55.11, I2 = 98.8%), and HDL ≤ 40 mg/dl for men and ≤ 50 mg/dl for women was 44.36% (95% CI: 31.82-56.90, I 2 = 98.8%). Conclusions The pooled prevalence of hypertriglyceridemia and other lipid abnormalities among DM patients was relatively high in Ethiopia. It strongly suggests the need to give maximal attention to the adherence of DM management to reduce the circulatory lipid profile abnormalities and subsequent complications. Prospero Registration. CRD42020182291.
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Abbasi Oshaghi E, Goodarzi MT, Higgins V, Adeli K. Role of resveratrol in the management of insulin resistance and related conditions: Mechanism of action. Crit Rev Clin Lab Sci 2017; 54:267-293. [DOI: 10.1080/10408363.2017.1343274] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Ebrahim Abbasi Oshaghi
- Department of Clinical Biochemistry, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Taghi Goodarzi
- Department of Clinical Biochemistry, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Victoria Higgins
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Khosrow Adeli
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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Joseph JT, Ganjifrockwala F, George G. Serum oxidized LDL and the factors associated with LDL oxidation in black South African type 2 diabetes mellitus patients. Int J Diabetes Dev Ctries 2017. [DOI: 10.1007/s13410-017-0559-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Abstract
Among the multiple modes of regulation of gene expression, translational control is arguably the least investigated and understood, and its role in vascular biology and pathobiology is not an exception. Here, we review recent studies that have revealed exciting translational regulatory phenomena and mechanisms involving novel RNA binding proteins and microRNA machinery in vascular biology. From these studies, the importance of translational regulation in angiogenesis, atherosclerosis, and blood pressure maintenance is beginning to emerge. We believe that the recent development of powerful techniques such as ribosome profiling and translating ribosome affinity purification (TRAP) will motivate and facilitate additional research in these areas.
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Urbanek MO, Galka-Marciniak P, Olejniczak M, Krzyzosiak WJ. RNA imaging in living cells - methods and applications. RNA Biol 2015; 11:1083-95. [PMID: 25483044 PMCID: PMC4615301 DOI: 10.4161/rna.35506] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Numerous types of transcripts perform multiple functions in cells, and these functions are mainly facilitated by the interactions of the RNA with various proteins and other RNAs. Insight into the dynamics of RNA biosynthesis, processing and cellular activities is highly desirable because this knowledge will deepen our understanding of cell physiology and help explain the mechanisms of RNA-mediated pathologies. In this review, we discuss the live RNA imaging systems that have been developed to date. We highlight information on the design of these systems, briefly discuss their advantages and limitations and provide examples of their numerous applications in various organisms and cell types. We present a detailed examination of one application of RNA imaging systems: this application aims to explain the role of mutant transcripts in human disease pathogenesis caused by triplet repeat expansions. Thus, this review introduces live RNA imaging systems and provides a glimpse into their various applications.
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Affiliation(s)
- Martyna O Urbanek
- a Department of Molecular Biomedicine; Institute of Bioorganic Chemistry; Polish Academy of Sciences ; Poznan , Poland
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Abstract
Cardiovascular disease is a major cause of morbidity and mortality in patients with type 2 diabetes mellitus, with a two- to fourfold increase in cardiovascular disease risk compared with non-diabetic individuals. Abnormalities in lipid metabolism that are observed in the context of type 2 diabetes are among the major factors contributing to an increased cardiovascular risk. Diabetic dyslipidaemia includes not only quantitative lipoprotein abnormalities, but also qualitative and kinetic abnormalities that, together, result in a shift towards a more atherogenic lipid profile. The primary quantitative lipoprotein abnormalities are increased triacylglycerol (triglyceride) levels and decreased HDL-cholesterol levels. Qualitative lipoprotein abnormalities include an increase in large, very low-density lipoprotein subfraction 1 (VLDL1) and small, dense LDLs, as well as increased triacylglycerol content of LDL and HDL, glycation of apolipoproteins and increased susceptibility of LDL to oxidation. The main kinetic abnormalities are increased VLDL1 production, decreased VLDL catabolism and increased HDL catabolism. In addition, even though LDL-cholesterol levels are typically normal in patients with type 2 diabetes, LDL particles show reduced turnover, which is potentially atherogenic. Although the pathophysiology of diabetic dyslipidaemia is not fully understood, the insulin resistance and relative insulin deficiency observed in patients with type 2 diabetes are likely to contribute to these lipid changes, as insulin plays an important role in regulating lipid metabolism. In addition, some adipocytokines, such as adiponectin or retinol-binding protein 4, may also contribute to the development of dyslipidaemia in patients with type 2 diabetes.
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Affiliation(s)
- Bruno Vergès
- Service Endocrinologie, Diabétologie et Maladies Métaboliques, Hôpital du Bocage, 2 bd Maréchal de Lattre de Tassigny, 21000, Dijon, France,
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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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Thedieck K, Holzwarth B, Prentzell MT, Boehlke C, Kläsener K, Ruf S, Sonntag AG, Maerz L, Grellscheid SN, Kremmer E, Nitschke R, Kuehn EW, Jonker JW, Groen AK, Reth M, Hall MN, Baumeister R. Inhibition of mTORC1 by astrin and stress granules prevents apoptosis in cancer cells. Cell 2013; 154:859-74. [PMID: 23953116 DOI: 10.1016/j.cell.2013.07.031] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 04/03/2013] [Accepted: 07/23/2013] [Indexed: 12/21/2022]
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) controls growth and survival in response to metabolic cues. Oxidative stress affects mTORC1 via inhibitory and stimulatory inputs. Whereas downregulation of TSC1-TSC2 activates mTORC1 upon oxidative stress, the molecular mechanism of mTORC1 inhibition remains unknown. Here, we identify astrin as an essential negative mTORC1 regulator in the cellular stress response. Upon stress, astrin inhibits mTORC1 association and recruits the mTORC1 component raptor to stress granules (SGs), thereby preventing mTORC1-hyperactivation-induced apoptosis. In turn, balanced mTORC1 activity enables expression of stress factors. By identifying astrin as a direct molecular link between mTORC1, SG assembly, and the stress response, we establish a unifying model of mTORC1 inhibition and activation upon stress. Importantly, we show that in cancer cells, apoptosis suppression during stress depends on astrin. Being frequently upregulated in tumors, astrin is a potential clinically relevant target to sensitize tumors to apoptosis.
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Affiliation(s)
- Kathrin Thedieck
- Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany.
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Haas ME, Attie AD, Biddinger SB. The regulation of ApoB metabolism by insulin. Trends Endocrinol Metab 2013; 24:391-7. [PMID: 23721961 PMCID: PMC3810413 DOI: 10.1016/j.tem.2013.04.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/10/2013] [Accepted: 04/12/2013] [Indexed: 01/07/2023]
Abstract
The leading cause of death in diabetic patients is cardiovascular disease. Apolipoprotein B (ApoB)-containing lipoprotein particles, which are secreted and cleared by the liver, are essential for the development of atherosclerosis. Insulin plays a key role in the regulation of ApoB. Insulin decreases ApoB secretion by promoting ApoB degradation in the hepatocyte. In parallel, insulin promotes clearance of circulating ApoB particles by the liver via the low-density lipoprotein receptor (LDLR), LDLR-related protein 1 (LRP1), and heparan sulfate proteoglycans (HSPGs). Consequently, the insulin-resistant state of type 2 diabetes (T2D) is associated with increased secretion and decreased clearance of ApoB. Here, we review the mechanisms by which insulin controls the secretion and uptake of ApoB in normal and diabetic livers.
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Affiliation(s)
- Mary E Haas
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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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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Adeli K. Translational control mechanisms in metabolic regulation: critical role of RNA binding proteins, microRNAs, and cytoplasmic RNA granules. Am J Physiol Endocrinol Metab 2011; 301:E1051-64. [PMID: 21971522 DOI: 10.1152/ajpendo.00399.2011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Regulated cell metabolism involves acute and chronic regulation of gene expression by various nutritional and endocrine stimuli. To respond effectively to endogenous and exogenous signals, cells require rapid response mechanisms to modulate transcript expression and protein synthesis and cannot, in most cases, rely on control of transcriptional initiation that requires hours to take effect. Thus, co- and posttranslational mechanisms have been increasingly recognized as key modulators of metabolic function. This review highlights the critical role of mRNA translational control in modulation of global protein synthesis as well as specific protein factors that regulate metabolic function. First, the complex lifecycle of eukaryotic mRNAs will be reviewed, including our current understanding of translational control mechanisms, regulation by RNA binding proteins and microRNAs, and the role of RNA granules, including processing bodies and stress granules. Second, the current evidence linking regulation of mRNA translation with normal physiological and metabolic pathways and the associated disease states are reviewed. A growing body of evidence supports a key role of translational control in metabolic regulation and implicates translational mechanisms in the pathogenesis of metabolic disorders such as type 2 diabetes. The review also highlights translational control of apolipoprotein B (apoB) mRNA by insulin as a clear example of endocrine modulation of mRNA translation to bring about changes in specific metabolic pathways. Recent findings made on the role of 5'-untranslated regions (5'-UTR), 3'-UTR, RNA binding proteins, and RNA granules in mediating insulin regulation of apoB mRNA translation, apoB protein synthesis, and hepatic lipoprotein production are discussed.
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Affiliation(s)
- Khosrow Adeli
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Atrium 3653, 555 University Ave., Toronto, ON, M5G 1X8 Canada.
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