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Dalen KT, Li Y. Regulation of lipid droplets and cholesterol metabolism in adrenal cortical cells. VITAMINS AND HORMONES 2023; 124:79-136. [PMID: 38408810 DOI: 10.1016/bs.vh.2023.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The adrenal gland is composed of two distinctly different endocrine moieties. The interior medulla consists of neuroendocrine chromaffin cells that secrete catecholamines like adrenaline and noradrenaline, while the exterior cortex consists of steroidogenic cortical cells that produce steroid hormones, such as mineralocorticoids (aldosterone), glucocorticoids (cortisone and cortisol) and androgens. Synthesis of steroid hormones in cortical cells requires substantial amounts of cholesterol, which is the common precursor for steroidogenesis. Cortical cells may acquire cholesterol from de novo synthesis and uptake from circulating low- and high-density lipoprotein particles (LDL and HDL). As cholesterol is part of the plasma membrane in all mammalian cells and an important regulator of membrane fluidity, cellular levels of free cholesterol are tightly regulated. To ensure a robust supply of cholesterol for steroidogenesis and to avoid cholesterol toxicity, cortical cells store large amounts of cholesterol as cholesteryl esters in intracellular lipid droplets. Cortical steroidogenesis relies on both mobilization of cholesterol from lipid droplets and constant uptake of circulating cholesterol to replenish lipid droplet stores. This chapter will describe mechanisms involved in cholesterol uptake, cholesteryl ester synthesis, lipid droplet formation, hydrolysis of stored cholesteryl esters, as well as their impact on steroidogenesis. Additionally, animal models and human diseases characterized by altered cortical cholesteryl ester storage, with or without abnormal steroidogenesis, will be discussed.
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Affiliation(s)
- Knut Tomas Dalen
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway; The Norwegian Transgenic Center, Institute of Basic Medical Sciences, University of Oslo, Norway.
| | - Yuchuan Li
- Department of Hepato-Pancreato-Biliary Surgery, Institute of Clinical Medicine, University of Oslo, Norway
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2
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Kennelly JP, Tontonoz P. Cholesterol Transport to the Endoplasmic Reticulum. Cold Spring Harb Perspect Biol 2023; 15:cshperspect.a041263. [PMID: 35940908 PMCID: PMC9899650 DOI: 10.1101/cshperspect.a041263] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Most cholesterol in mammalian cells is stored in the plasma membrane (PM). Cholesterol transport from the PM to low-sterol regulatory regions of the endoplasmic reticulum (ER) controls cholesterol synthesis and uptake, and thereby influences the rates of cholesterol flux between tissues of complex organisms. Cholesterol transfer to the ER is also required for steroidogenesis, oxysterol and bile acid synthesis, and cholesterol esterification. The ER-resident Aster proteins (Aster-A, -B, and -C) form contacts with the PM to move cholesterol to the ER in mammals. Mice lacking Aster-B have low adrenal cholesteryl ester stores and impaired steroidogenesis because of a defect in cholesterol transport from high-density lipoprotein (HDL) to the ER. This work reviews the molecular characteristics of Asters, their role in HDL- and low-density lipoprotein (LDL)-cholesterol movement, and how cholesterol transferred to the ER is utilized by cells. The roles of other lipid transporters and of membrane lipid organization in maintaining aspects of cholesterol homeostasis are also highlighted.
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Affiliation(s)
- John P Kennelly
- Department of Pathology and Laboratory Medicine, Department of Biological Chemistry, Molecular Biology Institute, University of California, Los Angeles, California 90095, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, Department of Biological Chemistry, Molecular Biology Institute, University of California, Los Angeles, California 90095, USA
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Warde KM, Lim YJ, Ribes Martinez E, Beuschlein F, O'Shea P, Hantel C, Dennedy MC. Mitotane Targets Lipid Droplets to Induce Lipolysis in Adrenocortical Carcinoma. Endocrinology 2022; 163:6633639. [PMID: 35797592 PMCID: PMC9342684 DOI: 10.1210/endocr/bqac102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Indexed: 01/14/2023]
Abstract
INTRODUCTION Adrenocortical carcinoma (ACC) is a rare aggressive cancer with low overall survival. Adjuvant mitotane improves survival but is limited by poor response rates and resistance. Mitotane's efficacy is attributed to the accumulation of toxic free cholesterol, predominantly through cholesterol storage inhibition. However, targeting this pathway has proven unsuccessful. We hypothesize that mitotane-induced free-cholesterol accumulation is also mediated through enhanced breakdown of lipid droplets. METHODOLOGY ATCC-H295R (mitotane-sensitive) and MUC-1 (mitotane-resistant) ACC cells were evaluated for lipid content using specific BODIPY dyes. Protein expression was evaluated by immunoblotting and flow cytometry. Cell viability was measured by quantifying propidium iodide-positive cells following mitotane treatment and pharmacological inhibitors of lipolysis. RESULTS H295R and MUC-1 cells demonstrated similar neutral lipid droplet numbers at baseline. However, evaluation of lipid machinery demonstrated distinct profiles in each model. Analysis of intracellular lipid droplet content showed H295R cells preferentially store cholesteryl esters, whereas MUC-1 cells store triacylglycerol. Decreased lipid droplets were associated with increased lipolysis in H295R and in MUC-1 at toxic mitotane concentrations. Pharmacological inhibition of lipolysis attenuated mitotane-induced toxicity in both models. CONCLUSION We highlight that lipid droplet breakdown and activation of lipolysis represent a putative additional mechanism for mitotane-induced cytotoxicity in ACC. Further understanding of cholesterol and lipids in ACC offers potential novel therapeutic exploitation, especially in mitotane-resistant disease.
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Affiliation(s)
- Kate M Warde
- Discipline of Pharmacology and Therapeutics, National University of Ireland, Galway, H91 TK33, Ireland
| | - Yi Jan Lim
- Discipline of Pharmacology and Therapeutics, National University of Ireland, Galway, H91 TK33, Ireland
| | - Eduardo Ribes Martinez
- Discipline of Pharmacology and Therapeutics, National University of Ireland, Galway, H91 TK33, Ireland
| | - Felix Beuschlein
- Department of Medicine IV, University Hospital, Ludwig Maximilian University of Munich, Munich, 81377, Germany
- Department of Endocrinology, Diabetes, and Clinical Nutrition, University Hospital Zurich, Zurich 8091, Switzerland
| | - Paula O'Shea
- Department of Clinical Biochemistry, Galway University Hospitals, Saolta Hospitals Group, Newcastle Road, Galway, H91 RW28, Ireland
| | - Constanze Hantel
- Department of Medicine IV, University Hospital, Ludwig Maximilian University of Munich, Munich, 81377, Germany
- Medizinische Klinik und Poliklinik III, University Hospital Carl Gustav Carus Dresden, 01307, Germany
| | - Michael Conall Dennedy
- Discipline of Pharmacology and Therapeutics, National University of Ireland, Galway, H91 TK33, Ireland
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Hoekstra M, Liu Q, Zhang Y, van der Wel EJ, Le Dévédec SE, Van Eck M. Hypocholesterolemic phospholipid transfer protein knockout mice exhibit a normal glucocorticoid response to food deprivation. Am J Transl Res 2022; 14:1884-1891. [PMID: 35422905 PMCID: PMC8991128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
OBJECTIVES Glucocorticoids, adrenal-derived steroid hormones, facilitate the physiological response to stress. High-density lipoproteins (HDL) are considered the primary source of cholesterol used for glucocorticoid synthesis in mice. Phospholipid transfer protein (PLTP) is a key player in HDL formation. In the current study we tested the hypothesis that HDL deficiency associated with genetic lack of PLTP negatively impacts the adrenal steroid function. METHODS We determined the glucocorticoid response to overnight food deprivation stress and the adrenal lipid and genetic phenotype of wild-type and PLTP knockout mice. RESULTS Basal plasma corticosterone levels, adrenal weights, and adrenocortical neutral lipid stores were not different between wild-type and PLTP knockout mice. Strikingly, plasma corticosterone levels were also equally high in the two groups of mice under fasting conditions (two-way ANOVA genotype effect: P>0.05). However, compensatory mechanisms were active to overcome adrenal lipid depletion, since gene expression levels of cholesterol synthesis, acquisition and mobilization proteins were ~2-fold higher in PLTP knockout adrenals versus wild-type adrenals. In support of an overall similar glucocorticoid stress response, hepatic relative mRNA expression levels of the glucocorticoid receptor target/glucocorticoid-sensitive genes PEPCK, ANGPTL4, FGF21, TDO2 and HMGCS2 were also not different. CONCLUSIONS We have shown that hypocholesterolemic PLTP knockout mice exhibit a normal glucocorticoid response to food deprivation. These novel data (1) highlight that the effect of HDL deficiency on adrenal glucocorticoid output in mice is model dependent and (2) imply that other (lipoprotein) cholesterol sources than HDL can also generate the pool utilized by adrenocortical cells to synthesize glucocorticoids.
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Affiliation(s)
- Menno Hoekstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden UniversityLeiden, Netherlands
| | - Qiuyu Liu
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden UniversityLeiden, Netherlands
| | - Yiheng Zhang
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden UniversityLeiden, Netherlands
| | - Ezra J van der Wel
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden UniversityLeiden, Netherlands
| | - Sylvia E Le Dévédec
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden UniversityLeiden, Netherlands
| | - Miranda Van Eck
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden UniversityLeiden, Netherlands
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5
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Ouweneel AB, Reiche ME, Snip OSC, Wever R, van der Wel EJ, Schaftenaar FH, Kauerova S, Lutgens E, Van Eck M, Hoekstra M. Apolipoprotein A1 deficiency in mice primes bone marrow stem cells for T cell lymphopoiesis. J Cell Sci 2022; 135:272619. [PMID: 34698355 PMCID: PMC8645231 DOI: 10.1242/jcs.258901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 10/14/2021] [Indexed: 11/20/2022] Open
Abstract
The bone marrow has emerged as a potentially important target in cardiovascular disease as it generates all leukocytes involved in atherogenesis. In the current study, we evaluated whether a change in bone marrow functionality underlies the increased atherosclerosis susceptibility associated with high-density lipoprotein (HDL) deficiency. We found that HDL deficiency in mice due to the genetic lack of hepatocyte-derived apolipoprotein A1 (APOA1) was associated with an increase in the Lin−Sca-1+Kit+ (LSK) bone marrow stem cell population and lymphoid-primed multipotent progenitor numbers, which translated into a higher production and systemic flux of T cell subsets. In accordance with APOA1 deficiency-associated priming of stem cells to increase T lymphocyte production, atherogenic diet-fed low-density lipoprotein receptor knockout mice transplanted with bone marrow from APOA1-knockout mice displayed marked lymphocytosis as compared to wild-type bone marrow recipients. However, atherosclerotic lesion sizes and collagen contents were similar in the two groups of bone marrow recipients. In conclusion, systemic lack of APOA1 primes bone marrow stem cells for T cell lymphopoiesis. Our data provide novel evidence for a regulatory role of HDL in bone marrow functioning in normolipidemic mice. Summary: Changes in cholesterol metabolism, that is, in high-density lipoprotein levels, can significantly impact leukocyte numbers via modulating bone marrow functionality.
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Affiliation(s)
- Amber B Ouweneel
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
| | - Myrthe E Reiche
- Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, University of Amsterdam, 1105AZ Amsterdam, The Netherlands
| | - Olga S C Snip
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
| | - Robbert Wever
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
| | - Ezra J van der Wel
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
| | - Frank H Schaftenaar
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
| | - Soňa Kauerova
- Laboratory for Atherosclerosis Research, Institute for Clinical and Experimental Medicine, 12111 Prague, Czech Republic
| | - Esther Lutgens
- Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, University of Amsterdam, 1105AZ Amsterdam, The Netherlands
| | - Miranda Van Eck
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
| | - Menno Hoekstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, 2333CC Leiden, The Netherlands
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Zhou X, Mo Z, Li Y, Huang L, Yu S, Ge L, Hu Y, Shi S, Zhang L, Wang L, Gao L, Yang G, Chu G. Oleic acid reduces steroidogenesis by changing the lipid type stored in lipid droplets of ovarian granulosa cells. J Anim Sci Biotechnol 2022; 13:27. [PMID: 35130983 PMCID: PMC8822748 DOI: 10.1186/s40104-021-00660-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/29/2021] [Indexed: 12/27/2022] Open
Abstract
Background Oleic acid is an abundant free fatty acid present in livestock that are in a negative energy-balance state, and it may have detrimental effects on female reproduction and fertility. Oleic acid induces lipid accumulation in bovine granulosa cells, which leads to a foam cell-like morphology and reduced steroidogenesis. However, why oleic acid increases lipid accumulation but decreases steroidogenesis remains unclear. This study focused on oleic acid’s effects on lipid type and steroidogenesis. Results Oleic acid increased the lipid accumulation in a concentration-dependent manner and mainly increased the triglyceride level and decreased the cholesterol ester level. Oleic acid also led to a decline in estradiol and progesterone production in porcine granulosa cells in vitro. In addition, oleic acid up-regulated the expression of CD36 and diacylglycerol acyltransferase 2, but down-regulated the expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, scavenger receptor class B member 1 and acetyl-Coenzyme A acetyltransferase 2, as well as steroidogenesis-related genes, including cytochrome P450 family 11 subfamily A member 1, cytochrome P450 family 19 subfamily A member 1 and 3 as well as steroidogenic acute regulatory protein at the mRNA and protein levels. An oleic acid-rich diet also enhanced the triglyceride levels and reduced the cholesterol levels in ovarian tissues of female mice, which resulted in lower estradiol levels than in control-fed mice. Compared with the control, decreases in estrus days and the numbers of antral follicles and corpora lutea, as well as an increase in the numbers of the atretic follicles, were found in the oleic acid-fed female mice. Conclusions Oleic acid changed the lipid type stored in lipid droplets of ovarian granulosa cells, and led to a decrease in steroidogenesis. These results improve our understanding of fertility decline in livestock that are in a negative energy-balance state.
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Affiliation(s)
- Xiaoge Zhou
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Zhaoyi Mo
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Yankun Li
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Liang Huang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Sihai Yu
- College of veterinary medicine, Northwest A&F University, Yangling, 712100, China
| | - Lan Ge
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Yamei Hu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Shengjie Shi
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Lutong Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Liguang Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Lei Gao
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China.,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Gongshe Yang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China. .,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China.
| | - Guiyan Chu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Yangling, 712100, China. .,Laboratory of Animal Fat Deposition & Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China.
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Chang X, Zhao Y, Qin S, Wang H, Wang B, Zhai L, Liu B, Gu HM, Zhang DW. Loss of Hepatic Surf4 Depletes Lipid Droplets in the Adrenal Cortex but Does Not Impair Adrenal Hormone Production. Front Cardiovasc Med 2021; 8:764024. [PMID: 34859075 PMCID: PMC8631933 DOI: 10.3389/fcvm.2021.764024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/20/2021] [Indexed: 11/13/2022] Open
Abstract
The adrenal gland produces steroid hormones to play essential roles in regulating various physiological processes. Our previous studies showed that knockout of hepatic Surf4 (Surf4LKO) markedly reduced fasting plasma total cholesterol levels in adult mice, including low-density lipoprotein and high-density lipoprotein cholesterol. Here, we found that plasma cholesterol levels were also dramatically reduced in 4-week-old young mice and non-fasted adult mice. Circulating lipoprotein cholesterol is an important source of the substrate for the production of adrenal steroid hormones. Therefore, we investigated whether adrenal steroid hormone production was affected in Surf4LKO mice. We observed that lacking hepatic Surf4 essentially eliminated lipid droplets and significantly reduced cholesterol levels in the adrenal gland; however, plasma levels of aldosterone and corticosterone were comparable in Surf4LKO and the control mice under basal and stress conditions. Further analysis revealed that mRNA levels of genes encoding enzymes important for hormone synthesis were not altered, whereas the expression of scavenger receptor class B type I (SR-BI), low-density lipoprotein receptor (LDLR) and 3-hydroxy-3-methyl-glutaryl-CoA reductase was significantly increased in the adrenal gland of Surf4LKO mice, indicating increased de novo cholesterol biosynthesis and enhanced LDLR and SR-BI-mediated lipoprotein cholesterol uptake. We also observed that the nuclear form of SREBP2 was increased in the adrenal gland of Surf4 LKO mice. Taken together, these findings indicate that the very low levels of circulating lipoprotein cholesterol in Surf4LKO mice cause a significant reduction in adrenal cholesterol levels but do not significantly affect adrenal steroid hormone production. Reduced adrenal cholesterol levels activate SREBP2 and thus increase the expression of genes involved in cholesterol biosynthesis, which increases de novo cholesterol synthesis to compensate for the loss of circulating lipoprotein-derived cholesterol in the adrenal gland of Surf4LKO mice.
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Affiliation(s)
- Xiaole Chang
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Yongfang Zhao
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Shucun Qin
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Hao Wang
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Bingxiang Wang
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Lei Zhai
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Boyan Liu
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Hong-Mei Gu
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Da-Wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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Axmann M, Plochberger B, Mikula M, Weber F, Strobl WM, Stangl H. Plasma Membrane Lipids: An Important Binding Site for All Lipoprotein Classes. MEMBRANES 2021; 11:membranes11110882. [PMID: 34832111 PMCID: PMC8622984 DOI: 10.3390/membranes11110882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 12/23/2022]
Abstract
Cholesterol is one of the main constituents of plasma membranes; thus, its supply is of utmost importance. This review covers the known mechanisms of cholesterol transfer from circulating lipoprotein particles to the plasma membrane, and vice versa. To achieve homeostasis, the human body utilizes cellular de novo synthesis and extracellular transport particles for supply of cholesterol and other lipids via the blood stream. These lipoprotein particles can be classified according to their density: chylomicrons, very low, low, and high-density lipoprotein (VLDL, LDL, and HDL, respectively). They deliver and receive their lipid loads, most importantly cholesterol, to and from cells by several redundant routes. Defects in one of these pathways (e.g., due to mutations in receptors) usually are not immediately fatal. Several redundant pathways, at least temporarily, compensate for the loss of one or more of them, but the defects trigger systemic diseases, such as atherosclerosis later on. Recently, intracellular membrane–membrane contact sites were shown to be involved in intracellular cholesterol transfer and the plasma membrane itself has been proposed to act as a binding site for lipoprotein-mediated cargo unloading.
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Affiliation(s)
- Markus Axmann
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstrasse 21, 4020 Linz, Austria; (M.A.); (B.P.); (F.W.)
| | - Birgit Plochberger
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstrasse 21, 4020 Linz, Austria; (M.A.); (B.P.); (F.W.)
| | - Mario Mikula
- Center for Pathobiochemistry and Genetics, Institute for Medical Genetics, Medical University of Vienna, Währingerstrasse 10, 1090 Vienna, Austria;
| | - Florian Weber
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstrasse 21, 4020 Linz, Austria; (M.A.); (B.P.); (F.W.)
| | - Witta Monika Strobl
- Center for Pathobiochemistry and Genetics, Institute for Medical Chemistry, Medical University of Vienna, Währingerstrasse 10, 1090 Vienna, Austria;
| | - Herbert Stangl
- Center for Pathobiochemistry and Genetics, Institute for Medical Chemistry, Medical University of Vienna, Währingerstrasse 10, 1090 Vienna, Austria;
- Correspondence:
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9
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Circadian regulation of apolipoprotein gene expression affects testosterone production in mouse testis. Theriogenology 2021; 174:9-19. [PMID: 34416563 DOI: 10.1016/j.theriogenology.2021.06.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 06/07/2021] [Accepted: 06/17/2021] [Indexed: 01/02/2023]
Abstract
The circadian clock system plays an important role in regulating testosterone synthesis in mammals. Male Bmal1-/- mice are infertile with low serum testosterone levels and decreased expression of testicular steroidogenic genes, suggesting that circadian clock genes regulate testosterone biosynthesis by activating steroidogenic gene transcription. However, whether the circadian clock regulates testosterone production via other genes remains unknown. Using Bmal1-/- mice and their wild-type (WT) siblings, we aimed to identify additional genes by which the circadian clock regulates testosterone synthesis. WT and Bmal1-/- mouse testes sections had similar normal morphologies, although there was a decrease in testicular spermatozoa in the Bmal1-/- mice. Low serum testosterone levels were detected in the Bmal1-/- mice. RNA sequencing identified 37 and 48 genes that were differentially expressed between WT and Bmal1-/- mouse testes at circadian time (CT2 and CT14), respectively. The cholesterol metabolism pathway was significantly enriched in the KEGG pathway analysis, and there was lower expression of three apolipoprotein genes (Apoa1, Apoa2, and Apoc3) at CT2 in the testes of Bmal1-/- mice than in those of WT mice. These decreases in Apoa1, Apoa2, and Apoc3 expression were verified by quantitative polymerase chain reaction analysis, which also revealed downregulation of the expression of the circadian clock (Per2, Dbp, and Nr1d1) and steroidogenic (StAR, Cyp11a1, and Hsd17b3) genes. The expression of circadian clock genes was relatively stable in WT mice over a 20-h period, whereas there was clear circadian rhythmic expression of Apoa1, Apoa2, Apoc3, StAR, Cyp11a1, Hsd3b2, and Hsd17b3. Bmal1-/- mice showed severely reduced expression of testicular circadian clock genes at three time points (CT4, CT12, and CT20), and a reduction in mRNA expression levels of Apo (Apoa1, Apoa2, and Apoc3) and steroidogenic (StAR, Cyp11a1, Hsd3b2, and Hsd17b3) genes. Oil Red O staining showed decreased lipid aggregation in the Leydig cells of Bmal1-/- mouse testes. Considering the vital role of Apo genes in high-density lipoprotein formation and cholesterol transport, the present data suggest that the circadian clock system regulates testosterone production by orchestrating the rhythmic expression of Apo genes. These data extend our understanding of the role of the circadian clock in regulating testosterone production in mammals.
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10
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Hoekstra M. Identification of scavenger receptor BI as a potential screening candidate for congenital primary adrenal insufficiency in humans. Am J Physiol Endocrinol Metab 2020; 319:E102-E104. [PMID: 32369415 DOI: 10.1152/ajpendo.00069.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucocorticoids belong to the superfamily of steroid hormones that are synthesized from the common precursor cholesterol. Adrenal gland-derived glucocorticoids, e.g., cortisol in humans and corticosterone in rodents, contribute to various processes essential for normal daily life. Glucocorticoid deficiency, also referred to as primary adrenal insufficiency, therefore, often becomes evident early in life and can be present with hypoglycemia, a failure to thrive, recurrent development of infections, and neurological problems, such as seizures and coma. The majority of congenital primary adrenal insufficiency cases are caused by deleterious mutations in genes involved in the intracellular mobilization of cholesterol and the subsequent conversion of cholesterol into glucocorticoids. A significant number of glucocorticoid deficiency cases, however, cannot be explained by known genetic variations. This perspective highlights existing literature regarding the importance of lipoprotein-derived cholesterol acquisition through scavenger receptor class B, type I (SR-BI/SCARB1) for the maintenance of an optimal adrenal glucocorticoid function in mice and humans. On the basis of the reviewed findings, it is suggested that the SCARB1 gene should be included in the standard glucocorticoid deficiency genetic screening panel to 1) facilitate knowledge development on the relative contribution of SR-BI-mediated cholesterol acquisition to steroid hormone synthesis in humans and 2) open up the possibility to reclassify glucocorticoid deficiency patients without a currently known genetic cause for concomitant treatment optimization.
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Affiliation(s)
- Menno Hoekstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratories, Leiden, The Netherlands
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11
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Traughber CA, Opoku E, Brubaker G, Major J, Lu H, Lorkowski SW, Neumann C, Hardaway A, Chung YM, Gulshan K, Sharifi N, Brown JM, Smith JD. Uptake of high-density lipoprotein by scavenger receptor class B type 1 is associated with prostate cancer proliferation and tumor progression in mice. J Biol Chem 2020; 295:8252-8261. [PMID: 32358065 PMCID: PMC7294086 DOI: 10.1074/jbc.ra120.013694] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/28/2020] [Indexed: 12/30/2022] Open
Abstract
High-density lipoprotein (HDL) metabolism is facilitated in part by scavenger receptor class B, type 1 (SR-B1) that mediates HDL uptake into cells. Higher levels of HDL have been associated with protection in other diseases, however, its role in prostate cancer is not definitive. SR-B1 is up-regulated in prostate cancer tissue, suggesting a possible role of this receptor in tumor progression. Here, we report that knockout (KO) of SR-B1 in both human and mouse prostate cancer cell lines through CRISPR/Cas9-mediated genome editing reduces HDL uptake into the prostate cancer cells and reduces their proliferation in response to HDL. In vivo studies using syngeneic SR-B1 WT (SR-B1+/+) and SR-B1 KO (SR-B1-/-) prostate cancer cells in WT and apolipoprotein-AI KO (apoA1-KO) C57BL/6J mice revealed that WT hosts, containing higher levels of total and HDL-cholesterol, grew larger tumors than apoA1-KO hosts with lower levels of total and HDL-cholesterol. Furthermore, SR-B1-/- prostate cancer cells formed smaller tumors in WT hosts than SR-B1+/+ cells in the same host model. Increased tumor volume was overall associated with reduced survival. We conclude that knocking out SR-B1 in prostate cancer tumors reduces HDL-associated increases in prostate cancer cell proliferation and disease progression.
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Affiliation(s)
- C Alicia Traughber
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Emmanuel Opoku
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Gregory Brubaker
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Jennifer Major
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Hanxu Lu
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Shuhui Wang Lorkowski
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Chase Neumann
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Aimalie Hardaway
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Yoon-Mi Chung
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Kailash Gulshan
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Nima Sharifi
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - J Mark Brown
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
- Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA
- Center for Microbiome and Human Health, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Jonathan D Smith
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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12
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Winge SB, Soraggi S, Schierup MH, Rajpert-De Meyts E, Almstrup K. Integration and reanalysis of transcriptomics and methylomics data derived from blood and testis tissue of men with 47,XXY Klinefelter syndrome indicates the primary involvement of Sertoli cells in the testicular pathogenesis. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:239-255. [PMID: 32449318 DOI: 10.1002/ajmg.c.31793] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/03/2020] [Accepted: 04/22/2020] [Indexed: 12/17/2022]
Abstract
Klinefelter syndrome (KS; 47,XXY) is the most common sex chromosomal anomaly and causes a multitude of symptoms. Often the most noticeable symptom is infertility caused by azoospermia with testicular histology showing hyalinization of tubules, germ cells loss, and Leydig cell hyperplasia. The germ cell loss begins early in life leading to partial hyalinization of the testis at puberty, but the mechanistic drivers behind this remain poorly understood. In this systematic review, we summarize the current knowledge on developmental changes in the cellularity of KS gonads supplemented by a comparative analysis of the fetal and adult gonadal transcriptome, and blood transcriptome and methylome of men with KS. We identified a high fraction of upregulated genes that escape X-chromosome inactivation, thus supporting previous hypotheses that these are the main drivers of the testicular phenotype in KS. Enrichment analysis showed overrepresentation of genes from the X- and Y-chromosome and testicular transcription factors. Furthermore, by re-evaluation of recent single cell RNA-sequencing data originating from adult KS testis, we found novel evidence that the Sertoli cell is the most affected cell type. Our results are consistent with disturbed cross-talk between somatic and germ cells in the KS testis, and with X-escapee genes acting as mediators.
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Affiliation(s)
- Sofia B Winge
- Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark
| | - Samuele Soraggi
- Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark
| | | | - Ewa Rajpert-De Meyts
- Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Almstrup
- Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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13
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van der Sluis RJ, Hoekstra M. Glucocorticoids are active players and therapeutic targets in atherosclerotic cardiovascular disease. Mol Cell Endocrinol 2020; 504:110728. [PMID: 31968221 DOI: 10.1016/j.mce.2020.110728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/19/2019] [Accepted: 01/17/2020] [Indexed: 02/07/2023]
Abstract
Adrenal-derived glucocorticoids mediate the physiological response to stress. Chronic disturbances in glucocorticoid homeostasis, i.e. in Addison's and Cushing's disease patients, predispose to the development of atherosclerotic cardiovascular disease. Here we review preclinical and clinical findings regarding the relation between changes in plasma glucocorticoid levels and the atherosclerosis extent. It appears that, although the altered glucocorticoid function can in most cases be restored in the different patient groups, current therapies do not necessarily reverse the associated risk for atherosclerotic cardiovascular disease. In our opinion much attention should therefore be given to the development of a Cushing's disease mouse model that can (1) effectively replicate the effect of hypercortisolemia on atherosclerosis outcome observed in humans and (2) be used to investigate, in a preclinical setting, the relative impact on atherosclerosis susceptibility of already available (e.g. metyrapone) and potentially novel (i.e. SR-BI activity modulators) therapeutic agents that target the adrenal glucocorticoid output.
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Affiliation(s)
- Ronald J van der Sluis
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratories, Einsteinweg 55, 2333CC, Leiden, the Netherlands
| | - Menno Hoekstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratories, Einsteinweg 55, 2333CC, Leiden, the Netherlands.
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14
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Kumar S, Balhara AK, Buragohain L, Kumar R, Sharma RK, Phulia SK, Mohanty AK, Singh I. Identification of novel proteomics markers involved in ovarian endocrinology of riverine buffalo ( Bubalus bubalis). BIOL RHYTHM RES 2019. [DOI: 10.1080/09291016.2019.1658061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Sunil Kumar
- Division of Animal Reproduction, ICAR-IVRI, Izatnagar, India
| | | | - Lukumoni Buragohain
- Department of Animal Biotechnology, College of Veterinary Science, AAU, Guwahati, India
| | - Rajesh Kumar
- Department of Veterinary Physiology, Kerala Veterinary and Animal Sciences University, Pookot, India
| | | | | | | | - Inderjeet Singh
- Division of Animal Physiology and Reproduction, ICAR-CIRB, Hisar, India
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15
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Shi JF, Li YK, Ren K, Xie YJ, Yin WD, Mo ZC. Characterization of cholesterol metabolism in Sertoli cells and spermatogenesis (Review). Mol Med Rep 2018; 17:705-713. [PMID: 29115523 PMCID: PMC5780145 DOI: 10.3892/mmr.2017.8000] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 08/31/2017] [Indexed: 01/21/2023] Open
Abstract
The Sertoli cell, which is the supporting cell of spermatogenesis, has an important role in the endocrine and paracrine control of spermatogenesis. Functionally, it provides the cells of the seminiferous epithelium with nutrition, conveys mature spermatids to the lumen of seminiferous tubules, secretes androgen‑binding protein and interacts with endocrine Leydig cells. In addition, the levels of cholesterol, as well as its intermediates, vary greatly between nongonadal tissues and the male reproductive system. Throughout spermatogenesis, a dynamic and constant alteration in the membrane lipid composition of Sertoli cells occurs. In several mammalian species, testis meiosis‑activating sterol and desmosterol, as well as other cholesterol precursors, accumulate in the testes and spermatozoa. In addition, certain cholesterogenic genes exhibit stage‑specific expression patterns during spermatogenesis, including the cytochrome P450 enzyme lanosterol 14α‑demethylase. Inconsistency in the patterns of gene expression during spermatogenesis indicates a cell‑type specific and complex temporary modulation of lipids and cholesterol, which also implicates the dynamic interactions between Sertoli cells and germ cells. Furthermore, in the female reproductive tract and during epididymal transit, which is a prerequisite for valid fertilization, the modulation of cholesterol occurring in spermatozoal membranes further indicates the functional importance of sterol compounds in spermatogenesis. However, the exact role of cholesterol metabolism in Sertoli cells in sperm production is unknown. The present review article describes the progress made in the research regarding the characteristics of the Sertoli cell, particularly the regulation of its cholesterol metabolism during spermatogenesis.
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Affiliation(s)
- Jin-Feng Shi
- Institute of Cardiovascular Disease, Medical School, University of South China, Hengyang, Hunan 421001, P.R. China
- Key Laboratory for Arteriosclerology of Hunan Province, Hengyang, Hunan 421001, P.R. China
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, Hunan 421001, P.R. China
| | - Yu-Kun Li
- Department of Histology and Embryology, Medical School, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Kun Ren
- Institute of Cardiovascular Disease, Medical School, University of South China, Hengyang, Hunan 421001, P.R. China
- Key Laboratory for Arteriosclerology of Hunan Province, Hengyang, Hunan 421001, P.R. China
| | - Yuan-Jie Xie
- Department of Histology and Embryology, Medical School, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Wei-Dong Yin
- Institute of Cardiovascular Disease, Medical School, University of South China, Hengyang, Hunan 421001, P.R. China
- Key Laboratory for Arteriosclerology of Hunan Province, Hengyang, Hunan 421001, P.R. China
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, Hunan 421001, P.R. China
| | - Zhong-Cheng Mo
- Department of Histology and Embryology, Medical School, University of South China, Hengyang, Hunan 421001, P.R. China
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16
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Abnormalities of Lipoprotein Levels in Liver Cirrhosis: Clinical Relevance. Dig Dis Sci 2018; 63:16-26. [PMID: 29177578 DOI: 10.1007/s10620-017-4862-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 11/19/2017] [Indexed: 12/17/2022]
Abstract
Progressive lipoprotein impairment occurs in liver cirrhosis and is associated with increased morbidity and mortality. The present review aims to summarize the current evidence regarding the prognostic value of lipoprotein abnormalities in liver cirrhosis and to address the need of a better prognostic stratification of patients, including lipoprotein profile assessment. Low levels of lipoproteins are usual in cirrhosis. Much evidence supports the prognostic role of hypolipidemia in cirrhotic patients. In particular, hypocholesterolemia represents an independent predictor of survival in cirrhosis. In cirrhotic patients, lipoprotein impairment is associated with several complications: infections, malnutrition, adrenal function, and spur cell anemia. Alterations of liver function are associated with modifications of circulating lipids. Decreased levels of lipoproteins significantly impact the survival of cirrhotic patients and play an important role in the pathogenesis of some cirrhosis-related complications.
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17
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Wei XB, Chen XJ, Li YL, Huang JL, Chen XL, Yu DQ, Tan N, Liu YH, Chen JY, He PC. Apolipoprotein A-I: A favorable prognostic marker in infective endocarditis. J Clin Lipidol 2017; 12:498-505. [PMID: 29339066 DOI: 10.1016/j.jacl.2017.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/10/2017] [Accepted: 12/12/2017] [Indexed: 01/29/2023]
Abstract
BACKGROUND Decreased apolipoprotein A-I (apoA-I) and high-density lipoprotein cholesterol (HDL-C) are common in inflammation and sepsis. No study with a large sample size has been performed to investigate the prognostic value of apoA-I or HDL-C in infective endocarditis (IE). OBJECTIVE The present study aimed to explore the prognostic value of apoA-I and HDL-C for adverse outcomes in IE patients. METHODS Patients with a definite diagnosis of IE between January 2009 and July 2015 were enrolled and divided into 3 groups according to their apoA-I tertiles at admission. Univariate and multivariate analyses were performed to evaluate the relationship of apoA-I and HDL-C with clinical outcomes. RESULTS Of the 593 included patients, 40 (6.7%) died in hospital. Patients with lower apoA-I experienced markedly higher rates of in-hospital mortality (10.7%, 7.0%, and 2.5% in tertiles 1-3, respectively; P = .006) and major adverse clinical events (32.5%, 24.1%, and 8.6% in tertiles 1-3, respectively; P < .001). ApoA-I (area under the curve, 0.671; P < .001) and HDL-C (area under the curve, 0.672; P < .001) had predictive values for in-hospital death. Multivariate logistic regression showed that apoA-I <0.90 g/L and HDL-C <0.78 mmol/L were independent risk predictors for in-hospital death. A multivariate Cox proportional hazard analysis revealed that apoA-I (increments of 1 g/L; hazard ratio, 0.36; 95% confidence interval, 0.15-0.87; P = .023) and HDL-C (increments of 1 mmol/L; hazard ratio, 0.38; 95% confidence interval, 0.18-0.83; P = .015) were independently associated with long-term mortality. CONCLUSIONS ApoA-I and HDL-C were inversely associated with adverse IE prognosis.
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Affiliation(s)
- Xue-Biao Wei
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China
| | - Xiao-Jin Chen
- Department of Internal Medicine, Longnan Medicine Hospital, Ganzhou, China
| | - Yuan-Ling Li
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China
| | - Jie-Leng Huang
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China
| | - Xiao-Lan Chen
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China
| | - Dan-Qing Yu
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China
| | - Ning Tan
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China
| | - Yuan-Hui Liu
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China.
| | - Ji-Yan Chen
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China.
| | - Peng-Cheng He
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong General Hospital, Guangdong Academic of Medical Sciences, Guangzhou, China; Department of Cardiology, The Second People's Hospital of Nanhai District, Guangdong General Hospital's Nanhai Hospital, Foshan, China.
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18
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Ouweneel AB, van der Sluis RJ, Nahon JE, Van Eck M, Hoekstra M. Simvastatin treatment aggravates the glucocorticoid insufficiency associated with hypocholesterolemia in mice. Atherosclerosis 2017; 261:99-104. [DOI: 10.1016/j.atherosclerosis.2017.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/30/2017] [Accepted: 02/17/2017] [Indexed: 11/26/2022]
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Hoekstra M, Van Eck M. HDL is redundant for adrenal steroidogenesis in LDLR knockout mice with a human-like lipoprotein profile. J Lipid Res 2016; 57:631-7. [PMID: 26891738 DOI: 10.1194/jlr.m066019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 11/20/2022] Open
Abstract
The contribution of HDL to adrenal steroidogenesis appears to be different between mice and humans. In the current study, we tested the hypothesis that a difference in lipoprotein profile may be the underlying cause. Hereto, we determined the impact of HDL deficiency on the adrenal glucocorticoid output in genetically modified mice with a human-like lipoprotein profile. Genetic deletion of APOA1 in LDL receptor (LDLR) knockout mice was associated with HDL deficiency and a parallel increase in the level of cholesterol associated with nonHDL fractions. Despite a compensatory increase in the adrenal relative mRNA expression levels of the cholesterol synthesis gene, HMG-CoA reductase, adrenals from APOA1/LDLR double knockout mice were severely depleted of neutral lipids, as compared with those of control LDLR knockout mice. However, basal corticosterone levels and the adrenal glucocorticoid response to stress were not different between the two types of mice. In conclusion, we have shown that HDL is not critical for proper adrenal glucocorticoid function when mice are provided with a human-like lipoprotein profile. Our findings provide the first experimental evidence that APOB-containing lipoproteins may facilitate adrenal steroidogenesis, in an LDLR-independent manner, in vivo in mice.
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Affiliation(s)
- Menno Hoekstra
- Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Gorlaeus Laboratories, 2333CC Leiden, The Netherlands
| | - Miranda Van Eck
- Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Gorlaeus Laboratories, 2333CC Leiden, The Netherlands
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20
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Wu DM, He Z, Chen T, Liu Y, Ma LP, Ping J. DNA hypermethylation of acetoacetyl-CoA synthetase contributes to inhibited cholesterol supply and steroidogenesis in fetal rat adrenals under prenatal nicotine exposure. Toxicology 2016; 340:43-52. [PMID: 26776438 DOI: 10.1016/j.tox.2016.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 12/28/2015] [Accepted: 01/10/2016] [Indexed: 11/16/2022]
Abstract
Prenatal nicotine exposure is a risk factor for intrauterine growth retardation (IUGR). Steroid hormones synthesized from cholesterol in the fetal adrenal play an important role in the fetal development. The aim of this study is to investigate the effects of prenatal nicotine exposure on steroidogenesis in fetal rat adrenals from the perspective of cholesterol supply and explore the underlying epigenetic mechanisms. Pregnant Wistar rats were administered 1.0mg/kg nicotine subcutaneously twice a day from gestational day (GD) 7 to GD17. The results showed that prenatal nicotine exposure increased IUGR rates. Histological changes, decreased steroid hormone concentrations and decreased cholesterol supply were observed in nicotine-treated fetal adrenals. In the gene expression array, the expression of genes regulating ketone metabolic process decreased in nicotine-treated fetal adrenals. The following conjoint analysis of DNA methylation array with these differentially expressed genes suggested that acetoacetyl-CoA synthetase (AACS), the enzyme utilizing ketones for cholesterol supply, may play an important role in nicotine-induced cholesterol supply deficiency. Moreover, the decreased expression of AACS and increased DNA methylation in the proximal promoter of AACS in the fetal adrenal was verified by real-time reverse-transcription PCR (RT-PCR) and bisulfite sequencing PCR (BSP), respectively. In conclusion, prenatal nicotine exposure can cause DNA hypermethylation of the AACS promoter in the rat fetal adrenal. These changes may result in decreased AACS expression and cholesterol supply, which inhibits steroidogenesis in the fetal adrenal.
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Affiliation(s)
- Dong-Mei Wu
- Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China
| | - Zheng He
- Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China
| | - Ting Chen
- Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China
| | - Yang Liu
- Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China
| | - Liang-Peng Ma
- Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China
| | - Jie Ping
- Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China; Hubei Provincial Key Laboratory of Developmentally Originated Diseases, Wuhan 430071, China.
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Bell CL, Murray SA. Adrenocortical Gap Junctions and Their Functions. Front Endocrinol (Lausanne) 2016; 7:82. [PMID: 27445985 PMCID: PMC4925680 DOI: 10.3389/fendo.2016.00082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/20/2016] [Indexed: 12/21/2022] Open
Abstract
Adrenal cortical steroidogenesis and proliferation are thought to be modulated by gap junction-mediated direct cell-cell communication of regulatory molecules between cells. Such communication is regulated by the number of gap junction channels between contacting cells, the rate at which information flows between these channels, and the rate of channel turnover. Knowledge of the factors regulating gap junction-mediated communication and the turnover process are critical to an understanding of adrenal cortical cell functions, including development, hormonal response to adrenocorticotropin, and neoplastic dedifferentiation. Here, we review what is known about gap junctions in the adrenal gland, with particular attention to their role in adrenocortical cell steroidogenesis and proliferation. Information and insight gained from electrophysiological, molecular biological, and imaging (immunocytochemical, freeze fracture, transmission electron microscopic, and live cell) techniques will be provided.
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Affiliation(s)
- Cheryl L. Bell
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sandra A. Murray
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- *Correspondence: Sandra A. Murray,
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Abstract
The adrenal gland is one of the prominent sites for steroid hormone synthesis. Lipoprotein-derived cholesterol esters (CEs) delivered via SR-B1 constitute the dominant source of cholesterol for steroidogenesis, particularly in rodents. Adrenocorticotropic hormone (ACTH) stimulates steroidogenesis through downstream actions on multiple components involved in steroidogenesis. Both acute and chronic ACTH treatments can modulate SR-B1 function, including its transcription, posttranscriptional stability, phosphorylation and dimerization status, as well as the interaction with other protein partners, all of which result in changes in the ability of SR-B1 to mediate HDL-CE uptake and the supply of cholesterol for conversion to steroids. Here, we provide a review of the recent findings on the regulation of adrenal SR-B1 function by ACTH.
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Affiliation(s)
- Wen-Jun Shen
- The Division of Endocrinology, Stanford University, Stanford, CA, USA
- Geriatric Research, Education and Clinical Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Salman Azhar
- The Division of Endocrinology, Stanford University, Stanford, CA, USA
- Geriatric Research, Education and Clinical Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Fredric B. Kraemer
- The Division of Endocrinology, Stanford University, Stanford, CA, USA
- Geriatric Research, Education and Clinical Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
- *Correspondence: Fredric B. Kraemer,
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Shen WJ, Azhar S, Kraemer FB. Lipid droplets and steroidogenic cells. Exp Cell Res 2015; 340:209-14. [PMID: 26639173 DOI: 10.1016/j.yexcr.2015.11.024] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 11/23/2015] [Accepted: 11/25/2015] [Indexed: 02/05/2023]
Abstract
Lipid droplets (LDs) in steroidogenic tissues have a cholesteryl ester (CE) core surrounded by a phospholipid monolayer that is coated with associated proteins. Compared with other tissues, they tend to be smaller in size and more numerous in numbers. These LDs are enriched with PLIN1c, PLIN2 and PLIN3. Both CIDE A and B are found in mouse ovary. Free cholesterol (FC) released upon hormone stimulation from LDs is the preferred source of cholesterol substrate for steroidogenesis, and HSL is the major neutral cholesterol esterase mediating the conversion of CEs to FC. Through the interaction of HSL with vimentin and StAR, FC is translocated to mitochondria for steroid hormone production. Proteomic analyses of LDs isolated from loaded primary ovarian granulosa cells, mouse MLTC-1 Leydig tumor cells and mouse testes revealed LD associated proteins that are actively involved in modulating lipid homeostasis along with a number of steroidogenic enzymes. Microscopy analysis confirmed the localization of many of these proteins to LDs. These studies broaden the role of LDs to include being a platform for functional steroidogenic enzyme activity or as a port for transferring steroidogenic enzymes and/or steroid intermediates, in addition to being a storage depot for CEs.
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Affiliation(s)
- Wen-Jun Shen
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford, CA 94305, United States; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, United States
| | - Salman Azhar
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford, CA 94305, United States; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, United States
| | - Fredric B Kraemer
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford, CA 94305, United States; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, United States.
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24
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Proteomic identification of plasma proteins as markers of growth promoter abuse in cattle. Anal Bioanal Chem 2015; 407:4495-507. [DOI: 10.1007/s00216-015-8651-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 03/13/2015] [Accepted: 03/18/2015] [Indexed: 12/31/2022]
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Spadaro L, Noto D, Privitera G, Tomaselli T, Fede G, Scicali R, Piro S, Fayer F, Altieri I, Averna M, Purrello F. Apolipoprotein AI and HDL are reduced in stable cirrhotic patients with adrenal insufficiency: a possible role in glucocorticoid deficiency. Scand J Gastroenterol 2015; 50:347-54. [PMID: 25592451 DOI: 10.3109/00365521.2014.985707] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUNDS AND AIMS Adrenal insufficiency (AI) has been reported in patients with stable cirrhosis. A lack of substrates has been suggested as a possible contributing pathogenic mechanism leading to glucocorticoid deficiency in these subjects. To better explore this hypothesis, we studied lipoproteins in cirrhotics with and without AI. METHODS A total of 81 cirrhotic patients and 30 normal volunteers were enrolled. The severity of liver disease was graded by Child-Pugh score. Total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride (TG), and apolipoprotein AI (Apo-AI) levels were evaluated. HDL subfractions were measured by gradient gel electrophoresis. Adrenal function was assessed by the Low-Dose Short Synacthen Test. RESULTS Cirrhotic patients showed a significant reduction of TC, HDL, LDL, TG, and Apo-AI levels compared with controls. HDL3 was significantly lower, while HDL2 was higher, in cirrhotics compared with the controls. AI was observed in 26 patients. TC, TG, HDL, and Apo-AI were significantly reduced in cirrhotics with AI compared with those with normal adrenal function. HDL2 and HDL3 did not differ between these two groups. Delta cortisol was related to TC (r = 0.30, p < 0.01), TG (r = 0.22, p = 0.05), and Apo-AI (r = 0.37, p < 0.001). Multivariate analysis revealed that Apo-AI and HDL were independently associated with AI. CONCLUSION Our study shows that TC, TG, HDL, and Apo-AI are reduced in cirrhotics with AI. In particular, because both HDL and Apo-AI play a primary role in providing substrates for steroidogenesis to adrenal cells, this deficiency may contribute to the pathogenesis of AI in these patients.
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Affiliation(s)
- Luisa Spadaro
- Department of Clinical and Molecular Biomedicine, Garibaldi Hospital, University of Catania , Catania , Italy
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Abstract
The purpose of this article is to review fundamentals in adrenal gland histophysiology. Key findings regarding the important signaling pathways involved in the regulation of steroidogenesis and adrenal growth are summarized. We illustrate how adrenal gland morphology and function are deeply interconnected in which novel signaling pathways (Wnt, Sonic hedgehog, Notch, β-catenin) or ionic channels are required for their integrity. Emphasis is given to exploring the mechanisms and challenges underlying the regulation of proliferation, growth, and functionality. Also addressed is the fact that while it is now well-accepted that steroidogenesis results from an enzymatic shuttle between mitochondria and endoplasmic reticulum, key questions still remain on the various aspects related to cellular uptake and delivery of free cholesterol. The significant progress achieved over the past decade regarding the precise molecular mechanisms by which the two main regulators of adrenal cortex, adrenocorticotropin hormone (ACTH) and angiotensin II act on their receptors is reviewed, including structure-activity relationships and their potential applications. Particular attention has been given to crucial second messengers and how various kinases, phosphatases, and cytoskeleton-associated proteins interact to ensure homeostasis and/or meet physiological demands. References to animal studies are also made in an attempt to unravel associated clinical conditions. Many of the aspects addressed in this article still represent a challenge for future studies, their outcome aimed at providing evidence that the adrenal gland, through its steroid hormones, occupies a central position in many situations where homeostasis is disrupted, thus highlighting the relevance of exploring and understanding how this key organ is regulated. © 2014 American Physiological Society. Compr Physiol 4:889-964, 2014.
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Affiliation(s)
- Nicole Gallo-Payet
- Division of Endocrinology, Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, and Centre de Recherche Clinique Étienne-Le Bel of the Centre Hospitalier Universitaire de Sherbrooke (CHUS), Sherbrooke, Quebec, Canada
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27
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Abstract
High-density lipoprotein (HDL) is considered to be an anti-atherogenic lipoprotein moiety. Generation of genetically modified (total body and tissue-specific knockout) mouse models has significantly contributed to our understanding of HDL function. Here we will review data from knockout mouse studies on the importance of HDL's major alipoprotein apoA-I, the ABC transporters A1 and G1, lecithin:cholesterol acyltransferase, phospholipid transfer protein, and scavenger receptor BI for HDL's metabolism and its protection against atherosclerosis in mice. The initial generation and maturation of HDL particles as well as the selective delivery of its cholesterol to the liver are essential parameters in the life cycle of HDL. Detrimental atherosclerosis effects observed in response to HDL deficiency in mice cannot be solely attributed to the low HDL levels per se, as the low HDL levels are in most models paralleled by changes in non-HDL-cholesterol levels. However, the cholesterol efflux function of HDL is of critical importance to overcome foam cell formation and the development of atherosclerotic lesions in mice. Although HDL is predominantly studied for its atheroprotective action, the mouse data also suggest an essential role for HDL as cholesterol donor for steroidogenic tissues, including the adrenals and ovaries. Furthermore, it appears that a relevant interaction exists between HDL-mediated cellular cholesterol efflux and the susceptibility to inflammation, which (1) provides strong support for the novel concept that inflammation and metabolism are intertwining biological processes and (2) identifies the efflux function of HDL as putative therapeutic target also in other inflammatory diseases than atherosclerosis.
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Affiliation(s)
- Menno Hoekstra
- Division of Biopharmaceutics, Gorlaeus Laboratories, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands,
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Duan Y, Fu W, Wang S, Ni Y, Zhao R. Cholesterol deregulation induced by chronic corticosterone (CORT) stress in pectoralis major of broiler chickens. Comp Biochem Physiol A Mol Integr Physiol 2014; 176:59-64. [DOI: 10.1016/j.cbpa.2014.07.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/18/2014] [Accepted: 07/09/2014] [Indexed: 12/31/2022]
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Wolff C, Krinner K, Schroeder JA, Straub RH. Inadequate corticosterone levels relative to arthritic inflammation are accompanied by altered mitochondria/cholesterol breakdown in adrenal cortex: a steroid-inhibiting role of IL-1β in rats. Ann Rheum Dis 2014; 74:1890-7. [DOI: 10.1136/annrheumdis-2013-203885] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 04/16/2014] [Indexed: 01/13/2023]
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30
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Guo L, Zheng Z, Ai J, Howatt DA, Mittelstadt PR, Thacker S, Daugherty A, Ashwell JD, Remaley AT, Li XA. Scavenger receptor BI and high-density lipoprotein regulate thymocyte apoptosis in sepsis. Arterioscler Thromb Vasc Biol 2014; 34:966-75. [PMID: 24603680 DOI: 10.1161/atvbaha.113.302484] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Thymocyte apoptosis is a major event in sepsis; however, how this process is regulated remains poorly understood. APPROACH AND RESULTS Septic stress induces glucocorticoids production which triggers thymocyte apoptosis. Here, we used scavenger receptor BI (SR-BI)-null mice, which are completely deficient in inducible glucocorticoids in sepsis, to investigate the regulation of thymocyte apoptosis in sepsis. Cecal ligation and puncture induced profound thymocyte apoptosis in SR-BI(+/+) mice, but no thymocyte apoptosis in SR-BI(-/-) mice because of lack of inducible glucocorticoids. Unexpectedly, supplementation of glucocorticoids only partly restored thymocyte apoptosis in SR-BI(-/-) mice. We demonstrated that high-density lipoprotein (HDL) is a critical modulator for thymocyte apoptosis. SR-BI(+/+) HDL significantly enhanced glucocorticoid-induced thymocyte apoptosis, but SR-BI(-/-) HDL had no such activity. Further study revealed that SR-BI(+/+) HDL modulates glucocorticoid-induced thymocyte apoptosis via promoting glucocorticoid receptor translocation, but SR-BI(-/-) HDL loses such regulatory activity. To understand why SR-BI(-/-) HDL loses its regulatory activity, we analyzed HDL cholesterol contents. There was 3-fold enrichment of unesterified cholesterol in SR-BI(-/-) HDL compared with SR-BI(+/+) HDL. Normalization of unesterified cholesterol in SR-BI(-/-) HDL by probucol administration or lecithin cholesteryl acyltransferase expression restored glucocorticoid-induced thymocyte apoptosis, and incorporating unesterified cholesterol into SR-BI(+/+) HDL rendered SR-BI(+/+) HDL dysfunctional. Using lckCre-GR(fl/fl) mice in which thymocytes lack cecal ligation and puncture-induced thymocyte apoptosis, we showed that lckCre-GR(fl/fl) mice were significantly more susceptible to cecal ligation and puncture-induced septic death than GR(fl/fl) control mice, suggesting that glucocorticoid-induced thymocyte apoptosis is required for protection against sepsis. CONCLUSIONS The findings in this study reveal a novel regulatory mechanism of thymocyte apoptosis in sepsis by SR-BI and HDL.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Cecum/microbiology
- Cecum/surgery
- Cells, Cultured
- Cholesterol, HDL/blood
- Corticosterone/metabolism
- Disease Models, Animal
- Female
- Humans
- Ligation
- Male
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Phosphatidylcholine-Sterol O-Acyltransferase/genetics
- Phosphatidylcholine-Sterol O-Acyltransferase/metabolism
- Probucol/pharmacology
- Protein Transport
- Punctures
- Receptors, Glucocorticoid/metabolism
- Scavenger Receptors, Class B/deficiency
- Scavenger Receptors, Class B/genetics
- Scavenger Receptors, Class B/metabolism
- Sepsis/blood
- Sepsis/metabolism
- Sepsis/microbiology
- Sepsis/pathology
- Signal Transduction
- Thymocytes/drug effects
- Thymocytes/metabolism
- Thymocytes/pathology
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Affiliation(s)
- Ling Guo
- From the Department of Pediatrics (L.G., Z.Z., J.A., X.-A.L.), Graduate Center for Nutritional Sciences (Z.Z., J.A., X.-A.L.), and Saha Cardiovascular Research Center (D.A.H., A.D., X.-A.L.), University of Kentucky College of Medicine, Lexington; and Laboratory of Immune Cell Biology, National Cancer Institute (P.R.M., J.D.A.) and Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute (S.T., A.T.R.), National Institutes of Health, Bethesda, MD
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Zhang T, Dai P, Cheng D, Zhang L, Chen Z, Meng X, Zhang F, Han X, Liu J, Pan J, Yang G, Zhang C. Obesity occurring in apolipoprotein E-knockout mice has mild effects on fertility. Reproduction 2014; 147:141-51. [DOI: 10.1530/rep-13-0470] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Apolipoprotein (Apo) family is implicated in lipid metabolism. There are five types of Apo: Apoa, Apob, Apoc, Apod, and Apoe. Apoe has been demonstrated to play a central role in lipoprotein metabolism and to be essential for efficient receptor-mediated plasma clearance of chylomicron remnants and VLDL remnant particles by the liver. Apoe-deficient (Apoe−/−) mice develop atherosclerotic plaques spontaneously, followed by obesity. In this study, we investigated whether lipid deposition caused by Apoe knockout affects reproduction in female mice. The results demonstrated that Apoe−/− mice were severely hypercholesterolemic, with their cholesterol metabolism disordered, and lipid accumulating in the ovaries causing the ovaries to be heavier compared with the WT counterparts. In addition, estrogen and progesterone decreased significantly at D 100. Quantitative PCR analysis demonstrated that at D 100 the expression of cytochromeP450 aromatase (Cyp19a1), 3β-hydroxysteroid dehydrogenase (Hsd3b), mechanistic target of rapamycin (Mtor), and nuclear factor-κB (Nfkb) decreased significantly, while that of BCL2-associated agonist of cell death (Bad) and tuberous sclerosis complex 2 (Tsc2) increased significantly in the Apoe−/− mice. However, there was no difference in the fertility rates of the Apoe−/− and WT mice; that is, obesity induced by Apoe knockout has no significant effect on reproduction. However, the deletion of Apoe increased the number of ovarian follicles and the ratio of ovarian follicle atresia and apoptosis. We believe that this work will augment our understanding of the role of Apoe in reproduction.
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Guo L, Ai J, Zheng Z, Howatt DA, Daugherty A, Huang B, Li XA. High density lipoprotein protects against polymicrobe-induced sepsis in mice. J Biol Chem 2013; 288:17947-53. [PMID: 23658016 DOI: 10.1074/jbc.m112.442699] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
HDL has been considered to be a protective factor in sepsis; however, most contributing studies were conducted using the endotoxic animal model, and evidence from clinically relevant septic animal models remains limited and controversial. Furthermore, little is known about the roles of HDL in sepsis other than LPS neutralization. In this study, we employed cecal ligation and puncture (CLP), a clinically relevant septic animal model, and utilized apoA-I knock-out (KO) and transgenic mice to elucidate the roles of HDL in sepsis. ApoA-I-KO mice were more susceptible to CLP-induced septic death as shown by the 47.1% survival of apoA-I-KO mice versus the 76.7% survival of C57BL/6J (B6) mice (p = 0.038). ApoA-I-KO mice had exacerbated inflammatory cytokine production during sepsis compared with B6 mice. Further study indicated that serum from apoA-I-KO mice displayed less capacity for LPS neutralization compared with serum from B6 mice. In addition, apoA-I-KO mice had less LPS clearance, reduced corticosterone generation, and impaired leukocyte recruitment in sepsis. In contrast to apoA-I-KO mice, apoA-I transgenic mice were moderately resistant to CLP-induced septic death compared with B6 mice. In conclusion, our findings reveal multiple protective roles of HDL in CLP-induced sepsis. In addition to its well established role in neutralization of LPS, HDL exerts its protection against sepsis through promoting LPS clearance and modulating corticosterone production and leukocyte recruitment. Our study supports efforts to raise HDL levels as a therapeutic approach for sepsis.
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Affiliation(s)
- Ling Guo
- Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
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Chadwick AC, Sahoo D. Functional genomics of the human high-density lipoprotein receptor scavenger receptor BI: an old dog with new tricks. Curr Opin Endocrinol Diabetes Obes 2013; 20:124-31. [PMID: 23403740 PMCID: PMC3967407 DOI: 10.1097/med.0b013e32835ed575] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE OF REVIEW The athero-protective role of scavenger receptor BI (SR-BI) is primarily attributed to its ability to selectively transfer cholesteryl esters from high-density lipoproteins (HDLs) to the liver during reverse cholesterol transport (RCT). In this review, we highlight recent findings that reveal the impact of SR-BI on lipid levels and cardiovascular disease in humans. Moreover, additional responsibilities of SR-BI in modulating adrenal and platelet function, as well as female fertility in humans, are discussed. RECENT FINDINGS Heterozygote carriers of P297S, S112F and T175A-mutant SR-BI receptors were identified in patients with high HDL-cholesterol levels. HDL from P297S-SR-BI carriers was unable to mediate macrophage cholesterol efflux, whereas hepatocytes expressing P297S-SR-BI were unable to mediate the selective uptake of HDL-cholesteryl esters. S112F and T175A-mutant receptors exhibited similar impaired cholesterol transport functions in vitro. Reduced SR-BI function in P297S carriers was also associated with decreased steroidogenesis and altered platelet function. Further, human population studies identified SCARB1 variants associated with female infertility. SUMMARY Identification of SR-BI variants confirms the key role of this receptor in influencing lipid levels and RCT in humans. A deeper understanding of the contributions of SR-BI to steroidogenesis, platelet function and fertility is required in light of exploration of HDL-raising therapies aimed at reducing cardiovascular risk.
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Affiliation(s)
- Alexandra C. Chadwick
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
| | - Daisy Sahoo
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
- Department of Medicine, Division of Endocrinology, Metabolism & Clinical Nutrition, Milwaukee, WI, 53226, USA
- To whom correspondence should be addressed: H4930 Health Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, Phone: 1-414-955-7414; Fax: 1-414-456-6570,
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Hoekstra M, Korporaal SJA, van der Sluis RJ, Hirsch-Reinshagen V, Bochem AE, Wellington CL, Van Berkel TJC, Kuivenhoven JA, Van Eck M. LCAT deficiency in mice is associated with a diminished adrenal glucocorticoid function. J Lipid Res 2012. [PMID: 23178225 DOI: 10.1194/jlr.m030080] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In vitro studies have suggested that HDL and apoB-containing lipoproteins can provide cholesterol for synthesis of glucocorticoids. Here we assessed adrenal glucocorticoid function in LCAT knockout (KO) mice to determine the specific contribution of HDL-cholesteryl esters to adrenal glucocorticoid output in vivo. LCAT KO mice exhibit an 8-fold higher plasma free cholesterol-to-cholesteryl ester ratio (P < 0.001) and complete HDL-cholesteryl ester deficiency. ApoB-containing lipoprotein and associated triglyceride levels are increased in LCAT KO mice as compared with C57BL/6 control mice (44%; P < 0.05). Glucocorticoid-producing adrenocortical cells within the zona fasciculata in LCAT KO mice are devoid of neutral lipids. However, adrenal weights and basal corticosterone levels are not significantly changed in LCAT KO mice. In contrast, adrenals of LCAT KO mice show compensatory up-regulation of genes involved in cholesterol synthesis (HMG-CoA reductase; 516%; P < 0.001) and acquisition (LDL receptor; 385%; P < 0.001) and a marked 40-50% lower glucocorticoid response to adrenocorticotropic hormone exposure, endotoxemia, or fasting (P < 0.001 for all). In conclusion, our studies show that HDL-cholesteryl ester deficiency in LCAT KO mice is associated with a 40-50% lower adrenal glucocorticoid output. These findings further highlight the important novel role for HDL as cholesterol donor for the synthesis of glucocorticoids by the adrenals.
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Affiliation(s)
- Menno Hoekstra
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden, The Netherlands.
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Silvennoinen R, Escola-Gil JC, Julve J, Rotllan N, Llaverias G, Metso J, Valledor AF, He J, Yu L, Jauhiainen M, Blanco-Vaca F, Kovanen PT, Lee-Rueckert M. Acute Psychological Stress Accelerates Reverse Cholesterol Transport via Corticosterone-Dependent Inhibition of Intestinal Cholesterol Absorption. Circ Res 2012; 111:1459-69. [DOI: 10.1161/circresaha.112.277962] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Rationale:
Psychological stress is associated with an increased risk of cardiovascular diseases. However, the connecting mechanisms of the stress-inducing activation of the hypothalamic-pituitary-adrenal axis with atherosclerosis are not well-understood.
Objective:
To study the effect of acute psychological stress on reverse cholesterol transport (RCT), which transfers peripheral cholesterol to the liver for its ultimate fecal excretion.
Methods and Results:
C57Bl/6J mice were exposed to restraint stress for 3 hours to induce acute psychological stress. RCT in vivo was quantified by measuring the transfer of [
3
H]cholesterol from intraperitoneally injected mouse macrophages to the lumen of the small intestine within the stress period. Surprisingly, stress markedly increased the contents of macrophage-derived [
3
H]cholesterol in the intestinal lumen. In the stressed mice, intestinal absorption of [
14
C]cholesterol was significantly impaired, the intestinal mRNA expression level of peroxisome proliferator–activated receptor-α increased, and that of the sterol influx transporter Niemann-Pick C1–like 1 decreased. The stress-dependent effects on RCT rate and peroxisome proliferator–activated receptor-α gene expression were fully mimicked by administration of the stress hormone corticosterone (CORT) to nonstressed mice, and they were blocked by the inhibition of CORT synthesis in stressed mice. Moreover, the intestinal expression of Niemann-Pick C1–like 1 protein decreased when circulating levels of CORT increased. Of note, when either peroxisome proliferator-activated receptor α or liver X receptor α knockout mice were exposed to stress, the RCT rate remained unchanged, although plasma CORT increased. This indicates that activities of both transcription factors were required for the RCT-accelerating effect of stress.
Conclusions:
Acute psychological stress accelerated RCT by compromising intestinal cholesterol absorption. The present results uncover a novel functional connection between the hypothalamic-pituitary-adrenal axis and RCT that can be triggered by a stress-induced increase in circulating CORT.
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Affiliation(s)
- Reija Silvennoinen
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Joan Carles Escola-Gil
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Josep Julve
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Noemi Rotllan
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Gemma Llaverias
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Jari Metso
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Annabel F. Valledor
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Jianming He
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Liqing Yu
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Matti Jauhiainen
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Francisco Blanco-Vaca
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Petri T. Kovanen
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
| | - Miriam Lee-Rueckert
- From the Wihuri Research Institute, Helsinki, Finland (R.S., P.T.K., M.L.-R.); Departament de Bioquimica, IIB Sant Pau-CIBER de Diabetes y Enfermedades Metabolicas Asociadas-Universitat Autonoma de Barcelona, Barcelona, Spain (J.C.E.-G., J.J., N.R., G.L., F.B.-V.); Department of Chronic Disease Prevention, National Institute for Health and Welfare, Public Health Genomics Research Unit Biomedicum, Helsinki, Finland (J.M., M.J.); Department of Physiology and Immunology, School of Biology, University
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Twiddy AL, Cox ME, Wasan KM. Knockdown of scavenger receptor class B type I reduces prostate specific antigen secretion and viability of prostate cancer cells. Prostate 2012; 72:955-65. [PMID: 22025344 DOI: 10.1002/pros.21499] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 09/19/2011] [Indexed: 01/22/2023]
Abstract
BACKGROUND Scavenger Receptor Class B Type I (SR-BI) facilitates influx of cholesterol to the cell from lipoproteins in the circulation. This influx of cholesterol may be important for many cellular functions, including synthesis of androgens. Castration-resistant prostate cancer tumors are able to synthesize androgens de novo in order to supplement the loss of exogenous sources often induced by androgen deprivation therapy. Silencing of SR-BI may impact the ability of prostate cancer cells, particularly those of castration-resistant state, to maintain the intracellular supply of androgens by removing a supply of cholesterol. METHODS SR-BI expression was knocked down using small interfering RNA in LNCaP and C4-2 cells. The effect of down-regulation of SR-BI on PSA production, cell toxicity, and cell viability was measured in both cell types. In addition, compensatory cholesterol synthesis activity was measured using the radiolabeled precursor, (14) C-acetate. RESULTS SR-BI protein expression is higher basally in C4-2 cells than LNCaP cells. Silencing of SR-BI expression to greater than 85% reduced PSA production in LNCaP and C4-2 SRBI-KD cells by 55% and 58% compared to negative control cells, respectively. SR-BI-KD C4-2 cells demonstrated significantly reduced cell viability (>25%) compared the NC cells. CONCLUSIONS The down-regulation of SR-BI significantly impacts PSA production of prostate cancer cells, as well as the viability of C4-2 cells in the presence and absence of HDL. This may indicate a deficiency in cholesterol availability to the androgen synthesis pathway or may implicate a role for SR-BI in prostate cancer signal transduction pathways.
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Affiliation(s)
- Alexis L Twiddy
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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Mattei J, Demissie S, Tucker KL, Ordovas JM. The APOA1/C3/A4/A5 cluster and markers of allostatic load in the Boston Puerto Rican Health Study. Nutr Metab Cardiovasc Dis 2011; 21:862-870. [PMID: 20674306 PMCID: PMC3004022 DOI: 10.1016/j.numecd.2010.02.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 02/08/2010] [Accepted: 02/15/2010] [Indexed: 11/25/2022]
Abstract
BACKGROUND AND AIMS The APOA1/C3/A4/A5 cluster encodes key regulators of plasma lipids. Interactions between dietary factors and single nucleotide polymorphisms (SNPs) in the cluster have been reported. Allostatic load, or physiological dysregulation in response to stress, has been implicated in shaping health disparities in ethnic groups. We aimed to determine the association between polymorphisms in the APOA1/C3/A4/A5 cluster with allostatic load parameters, alone, and in interaction with dietary fat intake in Puerto Ricans adults. METHODS AND RESULTS Data on demographic and anthropometric measures, lifestyle behaviors, and medication use, as well as blood and urine samples for biomarker analysis, were obtained from participants of the Boston Puerto Rican Health Study (n=821, age 45-75 y). The 12 polymorphisms analyzed were not associated with allostatic load parameters. Significant interactions were observed between dietary fat intake and APOA1-75 in association with waist circumference (WC), (P=0.005), APOC3-640 with diastolic blood pressure (DBP), (P=0.003), and APOA4 N147S and APOA5 S19W with systolic blood pressure (SBP), (P=0.001 and P=0.002, respectively). Puerto Ricans homozygous for the common allele of APOA1-75, APOA4 N147S and APOA5 S19W had lower WC and SBP when consuming <31% of total fat from energy, than participants with the minor allele. Participants heterozygous for APOC3-640 had lower DBP at total fat intake ≥31% from energy. CONCLUSION SNPs in APOA1/C3/A4/A5, as modulated by dietary fat intake, appear to influence allostatic load parameters in Puerto Ricans.
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Affiliation(s)
- J Mattei
- Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA, 02111 USA
- Friedman School of Nutrition Science and Policy at Tufts University, Boston, MA, 02111 USA
| | - S Demissie
- Department of Biostatistics, School of Public Health, Boston University, Boston, MA, 02108 USA
| | - KL Tucker
- Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA, 02111 USA
- Friedman School of Nutrition Science and Policy at Tufts University, Boston, MA, 02111 USA
| | - JM Ordovas
- Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA, 02111 USA
- Friedman School of Nutrition Science and Policy at Tufts University, Boston, MA, 02111 USA
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Gómez-Requeni P, de Vareilles M, Kousoulaki K, Jordal AEO, Conceição LEC, Rønnestad I. Whole body proteome response to a dietary lysine imbalance in zebrafish Danio rerio. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2011; 6:178-86. [PMID: 21440519 DOI: 10.1016/j.cbd.2011.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Revised: 02/28/2011] [Accepted: 02/28/2011] [Indexed: 12/18/2022]
Abstract
Lysine (Lys) is an indispensable amino acid (AA) and is generally the first limiting AA in most vegetable proteins used in fish feeds. Lys availability may thus limit protein synthesis and accretion, and growth of fish. Metabolic effects of dietary Lys imbalance were examined by 2D-proteomics using zebrafish as model. The Control diet (Lys: 2.47 g kg(-1)) was based on zebrafish carcass AA profiles previously obtained. Two other experimental diets were deficient in Lys [Lys(-); 1.34 g kg(-1)] and Lys added in excess [Lys(+); 4.63 g kg(-1)]. Fish growth was monitored from 33 to 49 days post-fertilization and the whole body proteome screened by means of two-dimension gel electrophoresis and mass spectrometry. Growth rate was negatively affected in group Lys(-). Comparative proteomic analysis showed 45 spots differentially expressed among groups. Twenty-nine of these proteins were identified revealing proteins involved in muscle growth, energy and lipid metabolism, eye lens differentiation, chaperone activity and apoptosis. Lys deficiency is accompanied by a down-regulation of muscle proteins and up-regulation of proteins affected by fasting, energy deficit, growth arrest and apoptosis. Excess Lys was accompanied by an up-regulation of proteins related to glycolysis, steroidogenesis and sexual maturation.
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Affiliation(s)
- Pedro Gómez-Requeni
- Department of Biology, University of Bergen, High Technology Center, Norway.
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Hoekstra M, Korporaal SJA, Li Z, Zhao Y, Van Eck M, Van Berkel TJC. Plasma lipoproteins are required for both basal and stress-induced adrenal glucocorticoid synthesis and protection against endotoxemia in mice. Am J Physiol Endocrinol Metab 2010; 299:E1038-43. [PMID: 20858753 DOI: 10.1152/ajpendo.00431.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lipoprotein-associated cholesterol has been suggested to make a significant contribution to adrenal steroidogenesis in vivo. To determine whether lipoproteins indeed contribute to optimal adrenal steroidogenesis in mice, in the current study we have determined the effect of relative lipoprotein deficiency on adrenal steroidogenesis in C57BL/6 wild-type mice. Feeding C57BL/6 mice the lipid-lowering drug probucol (0.25% wt/wt) for 2 wk induced a 90% decrease in plasma high-density lipoprotein (HDL) cholesterol levels and a 77% reduction in low-density lipoprotein (LDL) cholesterol levels. Neutral lipid stores were depleted upon probucol treatment specifically in the glucocorticoid-producing zona fasciculata of the adrenal, leading to a 44% decreased plasma corticosterone level under basal conditions. Exposure to lipopolysaccharide (LPS) induced a 37% increase in the adrenal uptake of HDL cholesteryl esters. Probucol-treated mice could induce only a relatively minor corticosterone response upon a LPS challenge compared with controls, which coincided with an approximately twofold increased hepatic expression level of interleukin-6 and tumor necrosis factor (TNF)α and an 89% higher TNFα response in plasma. Furthermore, a compensatory two- to fivefold upregulation of LDL receptor (cholesterol uptake) and HMG-CoA reductase (cholesterol synthesis) expression was noticed in the adrenals of probucol-treated mice. In conclusion, we have shown that lipoprotein deficiency in mice as a result of probucol feeding is associated with decreased adrenal cortex cholesterol levels, a lower basal and stress-induced plasma glucocorticoid level, and an increased susceptibility to LPS-induced inflammation. Therefore, it is suggested that plasma lipoproteins are required for optimal adrenal steroidogenesis and protection against endotoxemia in mice.
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Affiliation(s)
- Menno Hoekstra
- Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden, The Netherlands.
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Twiddy AL, Leon CG, Wasan KM. Cholesterol as a Potential Target for Castration-Resistant Prostate Cancer. Pharm Res 2010; 28:423-37. [DOI: 10.1007/s11095-010-0210-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 06/28/2010] [Indexed: 01/15/2023]
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Mavridou S, Venihaki M, Rassouli O, Tsatsanis C, Kardassis D. Feedback inhibition of human scavenger receptor class B type I gene expression by glucocorticoid in adrenal and ovarian cells. Endocrinology 2010; 151:3214-24. [PMID: 20463057 DOI: 10.1210/en.2009-1302] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Scavenger receptor class B type I (SR-BI) facilitates the reverse transport of excess cholesterol from peripheral tissues to the liver via high-density lipoproteins. In steroidogenic tissues, SR-BI supplies cholesterol for steroid hormone production. We show here that the transcription of the human SR-BI gene is subject to feedback inhibition by glucocorticoid in adrenal and ovarian cells. SR-BI mRNA levels were increased in adrenals from corticosterone-insufficient Crh(-/-) mice, whereas corticosterone replacement by oral administration inhibited SR-BI gene expression in these mice. SR-BI mRNA levels were increased in adrenals from wild-type mice treated with metyrapone, a drug that blocks corticosterone synthesis. Experiments in adrenocortical H295R and ovarian SKOV-3 cells using cycloheximide and siRNA-mediated gene silencing revealed that glucocorticoid-mediated inhibition of SR-BI gene transcription requires de novo protein synthesis and the glucocorticoid receptor (GR). No direct binding of GR to the SR-BI promoter could be demonstrated in vitro and in vivo, suggesting an indirect mechanism of repression of SR-BI gene transcription by GR in adrenal cells. Deletion analysis established that the region of the human SR-BI promoter between nucleotides -201 and -62 is sufficient to mediate repression by glucocorticoid. This region contains putative binding sites for transcriptional repressors that could play a role in SR-BI gene regulation in response to glucocorticoid. In summary, this is the first report showing that glucocorticoid suppress SR-BI expression suggesting that steroidogenic tissues maintain steroid hormone homeostasis by prohibiting SR-BI-mediated high-density lipoprotein cholesterol uptake when the endogenous levels of glucocorticoid are elevated.
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Affiliation(s)
- Sofia Mavridou
- Department of Basic Sciences, Foundation of Research and Technology-Hellas, Heraklion 71003, Greece
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Gamliel-Lazarovich A, Gantman A, Shiner M, Coleman R, Aviram M, Keidar S. Paraoxonase 1 deficiency in mice is associated with reduced steroid biosynthesis: Effects on HDL binding, cholesteryl ester accumulation and scavenger receptor type BI expression. Atherosclerosis 2010; 211:130-5. [DOI: 10.1016/j.atherosclerosis.2010.01.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 01/14/2010] [Accepted: 01/28/2010] [Indexed: 10/19/2022]
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Vaessen SFC, Veldman RJ, Comijn EM, Snapper J, Sierts JA, van den Oever K, Beattie SG, Twisk J, Kuivenhoven JA. AAV gene therapy as a means to increase apolipoprotein (Apo) A-I and high-density lipoprotein-cholesterol levels: correction of murine ApoA-I deficiency. J Gene Med 2009; 11:697-707. [PMID: 19431216 DOI: 10.1002/jgm.1344] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Inherited apolipoprotein (Apo) A-I deficiency is an orphan disorder characterized by high-density lipoprotein (HDL)-cholesterol deficiency and premature atherosclerosis. Constitutive over-expression of ApoA-I might provide a means to treat this disease. The present study provides a comprehensive evaluation of adeno-associated virus (AAV)-mediated ApoA-I gene delivery to express human (h)ApoA-I and correct the low HDL-cholesterol phenotype associated with ApoA-I deficiency. METHODS In an effort to maximize AAV-mediated gene expression, we performed head-to-head comparisons of recombinant AAVs with pseudotype capsids 1, 2, 6 and 8 administered by different routes with the use of five different liver-specific promoters in addition to cytomegalovirus as single-stranded or as self-complementary (sc) AAV vectors. RESULTS Intravenous administration of 1 x 10(13) gc/kg scAAV8, in combination with the liver-specific promoter LP1, in female ApoA-I(-/-) mice resulted in hApoA-I expression levels of 634 +/- 69 mg/l, which persisted for the duration of the study (15 weeks). This treatment resulted in full recovery of HDL-cholesterol levels with correction of HDL particle size and apolipoprotein composition. In addition, we observed increased adrenal cholesterol content and a significant increase in bodyweight in treated mice. CONCLUSIONS The present study demonstrates that systemic delivery of a scAAV8 vector provides a means for efficient liver expression of hApoA-I, thereby correcting the lipid abnormalities associated with murine ApoA-I deficiency. Importantly, the study demonstrates that AAV-based gene therapy can be used to express therapeutic proteins at a high level for a prolonged period of time and, as such, provides a basis for further development of this strategy to treat hApoA-I deficiency.
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Affiliation(s)
- Stefan F C Vaessen
- Department of Experimental Vascular Medicine, Academic Medical Centre, Amsterdam, the Netherlands
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Xu J, Lecanu L, Tan M, Greeson J, Papadopoulos V. Identification of a benzamide derivative that inhibits stress-induced adrenal corticosteroid synthesis. Molecules 2009; 14:3392-410. [PMID: 19783933 PMCID: PMC6254727 DOI: 10.3390/molecules14093392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 08/14/2009] [Accepted: 09/01/2009] [Indexed: 11/30/2022] Open
Abstract
Elevated serum glucocorticoid levels contribute to the progression of many diseases, including depression, Alzheimer’s disease, hypertension, and acquired immunodeficiency syndrome. Here we show that the benzamide derivative N-[2-(4-cyclopropanecarbonyl-3-methyl-piperazin-1-yl)-1-(tert-butyl-1H-indol-3-yl-methyl)-2-oxo-ethyl]-4-nitrobenzamide (SP-10) inhibits dibutyryl cyclic AMP (dbcAMP)-induced corticosteroid synthesis in a dose-dependent manner in Y-1 adrenal cortical mouse tumor cells, without affecting basal steroid synthesis and reduced stress-induced corticosterone increases in rats without affecting the physiological levels of the steroid in blood. SP-10 did not affect cholesterol transport and metabolism by the mitochondria but was unexpectedly found to increase 3-hydroxy-3-methylglutaryl-coenzyme A, low density lipoprotein receptor, and scavenger receptor class B type I (SR-BI) expression. However, it also markedly reduced dbcAMP-induced NBD-cholesterol uptake, suggesting that this is a compensatory mechanism aimed at maintaining cholesterol levels. SP-10 also induced a redistribution of filamentous (F-) and monomeric (G-) actin, leading to decreased actin levels in the submembrane cytoskeleton suggesting that SP-10-induced changes in actin distribution might prevent the formation of microvilli– cellular structures required for SR-BI-mediated cholesterol uptake in adrenal cells.
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Affiliation(s)
- Jing Xu
- Department of Biochemistry & Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA; E-mails: (J.X.); (M.T.)
| | - Laurent Lecanu
- Department of Biochemistry & Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA; E-mails: (J.X.); (M.T.)
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, H3G 1A4, Canada; E-mail: (L.L.)
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
| | - Matthew Tan
- Department of Biochemistry & Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA; E-mails: (J.X.); (M.T.)
| | - Janet Greeson
- Samaritan Pharmaceuticals, Las Vegas, NV 89109, USA; E-mail: (J.G.)
| | - Vassilios Papadopoulos
- Department of Biochemistry & Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA; E-mails: (J.X.); (M.T.)
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, H3G 1A4, Canada; E-mail: (L.L.)
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Author to whom correspondence should be addressed; E-mail: ; Tel.: +514 934 1934 ext. 44580; Fax: +514 934 8439
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Rone MB, Fan J, Papadopoulos V. Cholesterol transport in steroid biosynthesis: role of protein-protein interactions and implications in disease states. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:646-58. [PMID: 19286473 DOI: 10.1016/j.bbalip.2009.03.001] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Revised: 02/28/2009] [Accepted: 03/03/2009] [Indexed: 12/20/2022]
Abstract
The transfer of cholesterol from the outer to the inner mitochondrial membrane is the rate-limiting step in hormone-induced steroid formation. To ensure that this step is achieved efficiently, free cholesterol must accumulate in excess at the outer mitochondrial membrane and then be transferred to the inner membrane. This is accomplished through a series of steps that involve various intracellular organelles, including lysosomes and lipid droplets, and proteins such as the translocator protein (18 kDa, TSPO) and steroidogenic acute regulatory (StAR) proteins. TSPO, previously known as the peripheral-type benzodiazepine receptor, is a high-affinity drug- and cholesterol-binding mitochondrial protein. StAR is a hormone-induced mitochondria-targeted protein that has been shown to initiate cholesterol transfer into mitochondria. Through the assistance of proteins such as the cAMP-dependent protein kinase regulatory subunit Ialpha (PKA-RIalpha) and the PKA-RIalpha- and TSPO-associated acyl-coenzyme A binding domain containing 3 (ACBD3) protein, PAP7, cholesterol is transferred to and docked at the outer mitochondrial membrane. The TSPO-dependent import of StAR into mitochondria, and the association of TSPO with the outer/inner mitochondrial membrane contact sites, drives the intramitochondrial cholesterol transfer and subsequent steroid formation. The focus of this review is on (i) the intracellular pathways and protein-protein interactions involved in cholesterol transport and steroid biosynthesis and (ii) the roles and interactions of these proteins in endocrine pathologies and neurological diseases where steroid synthesis plays a critical role.
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Affiliation(s)
- Malena B Rone
- The Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, 1650 Cedar Avenue, Montreal, Quebec, Canada H3G 1A4
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Connelly MA. SR-BI-mediated HDL cholesteryl ester delivery in the adrenal gland. Mol Cell Endocrinol 2009; 300:83-8. [PMID: 18840501 DOI: 10.1016/j.mce.2008.09.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 09/04/2008] [Indexed: 10/21/2022]
Abstract
In adrenocortical cells, scavenger receptor class B, type I (SR-BI) is localized in specialized plasma membrane compartments, called microvillar channels, that retain high density lipoprotein particles (HDL) and are sites for the selective uptake of cholesteryl esters (CE). Formation of microvillar channels is regulated by adrenocorticotropic hormone (ACTH) and requires SR-BI expression. Subsequent to SR-BI-mediated delivery to the plasma membrane, HDL-CE is metabolized to free cholesterol by hormone sensitive lipase and transported to the mitochondria for steroid synthesis via START domain proteins. The relevance of SR-BI to adrenal steroidogenesis is evident by the impairment of glucocorticoid-mediated stress response in the absence of SR-BI-mediated HDL-CE uptake in mice. On the molecular level, SR-BI mediates HDL-CE selective uptake by forming a hydrophobic channel. In addition, SR-BI facilitates bi-directional flux of cholesterol by modifying the phospholipid content of the plasma membrane. SR-BI most likely accomplishes these functions by forming homo-oligomers in the plasma membrane. Examination of SR-BI oligomerization using fluorescence resonance energy transfer spectroscopy revealed that SR-BI multimerizes via its C-terminal region. Overall, SR-BI is the cell surface receptor responsible for selective uptake of lipoprotein cholesterol and its ultimate delivery to sites of hormone synthesis in steroidogenic tissues.
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Affiliation(s)
- Margery A Connelly
- Metabolic Diseases, Johnson & Johnson Pharmaceutical Research and Development, LLC, Welsh & McKean Roads, Spring House, PA 19477-0776, United States.
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Murao K, Imachi H, Yu X, Cao WM, Muraoka T, Dobashi H, Hosomi N, Haba R, Iwama H, Ishida T. The transcriptional factor prolactin regulatory element-binding protein mediates the gene transcription of adrenal scavenger receptor class B type I via 3',5'-cyclic adenosine 5'-monophosphate. Endocrinology 2008; 149:6103-12. [PMID: 18755803 DOI: 10.1210/en.2008-0380] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Prolactin regulatory element-binding (PREB) protein is a transcription factor that regulates prolactin promoter activity in the rat anterior pituitary. The PREB protein is not only expressed in the anterior pituitary but also in the adrenal gland. However, the role of PREB in the adrenal gland is not clearly understood. Scavenger receptor class B type I (SR-BI) is a receptor for high-density lipoprotein that mediates the cellular uptake of high-density lipoprotein-cholesteryl ester and is a major route for cholesterol delivery to the steroidogenic pathway in the adrenal gland. In the present study, we have examined the role of PREB in regulating SR-BI. SR-BI expression was found to be regulated by cAMP, which stimulated the expression of PREB in a dose-dependent manner. Conversely, overexpression of PREB using a PREB-expressing adenovirus increased the expression of the SR-BI protein in the adrenocortical cell line Y-1. In addition, PREB induced the expression of the luciferase reporter protein that was under the control of the SR-BI promoter. EMSA showed that PREB mediates its transcriptional effect by binding to the PREB-responsive cis-element of the SR-BI promoter. Finally, we used small interfering RNA to inhibit PREB expression in the Y-1 cells and demonstrated that the knockdown of PREB expression attenuated the effects of cAMP on SR-BI expression. In summary, our data showed that in the adrenal gland, PREB regulates the transcription of the SR-BI gene via cAMP.
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Affiliation(s)
- Koji Murao
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe Miki-CHO, Kita-gun, Kagawa 761-0793, Japan.
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Karpac J, Czyzewska K, Kern A, Brush RS, Anderson RE, Hochgeschwender U. Failure of adrenal corticosterone production in POMC-deficient mice results from lack of integrated effects of POMC peptides on multiple factors. Am J Physiol Endocrinol Metab 2008; 295:E446-55. [PMID: 18559987 DOI: 10.1152/ajpendo.00762.2007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Production of corticosteroids from the adrenal gland is a multistep process in which corticosterone is enzymatically processed from its precursor cholesterol. The main hormone regulating the production of corticosterone is the proopiomelanocortin (POMC)-derived adrenocorticotropic hormone (ACTH). Adrenals of POMC-deficient (POMC(-/-)) mice do not produce corticosterone either at basal levels or in response to acute stimulation with ACTH. However, pharmacological amounts of ACTH delivered continuously elicit corticosterone production over time. To define the relative effects of ACTH on individual factors involved in corticosterone production, parameters of adrenal cholesterol metabolism and steroidogenesis were examined in POMC(-/-) mice compared with wild-type and ACTH-treated mutant mice. POMC(-/-) adrenals lack cholesterol esters (CE); adrenal CE is restored with ACTH treatment. However, discontinuation of ACTH treatment stops corticosterone production despite the presence of adrenal CE. Failure of corticosterone production by POMC(-/-) adrenals occurs despite the constitutive presence of transcripts of genes required for cholesterol metabolism and steroidogenesis. Levels of key proteins involved in selective cholesterol uptake and steroidogenesis were attenuated; ACTH treatment increased these protein levels, most significantly those of the receptor responsible for selective uptake of CE, scavenger receptor class B, type I (SR-BI). Our studies reveal that failure of corticosterone production of POMC(-/-) adrenal glands and its pharmacological reconstitution by ACTH are not mediated by any one individual protein, but rather as an integrated effect on multiple factors from import of the substrate cholesterol to its conversion to corticosterone.
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Affiliation(s)
- Jason Karpac
- Department of Neurobiology, Duke University Medical Center, 421 Research Drive, Durham, NC 27710, USA
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