1
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Nava M, Rowe SJ, Taylor RJ, Kahne D, Nocera DG. Determination of Initial Rates of Lipopolysaccharide Transport. Biochemistry 2024; 63:2440-2448. [PMID: 39264328 PMCID: PMC11447908 DOI: 10.1021/acs.biochem.4c00379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 08/28/2024] [Accepted: 08/30/2024] [Indexed: 09/13/2024]
Abstract
Nonvesicular lipid trafficking pathways are an important process in every domain of life. The mechanisms of these processes are poorly understood in part due to the difficulty in kinetic characterization. One important class of glycolipids, lipopolysaccharides (LPS), are the primary lipidic component of the outer membrane of Gram-negative bacteria. LPS are synthesized in the inner membrane and then trafficked to the cell surface by the lipopolysaccharide transport proteins, LptB2FGCADE. By characterizing the interaction of a fluorescent probe and LPS, we establish a quantitative assay to monitor the flux of LPS between proteoliposomes on the time scale of seconds. We then incorporate photocaged ATP into this system, which allows for light-based control of the initiation of LPS transport. This control allows us to measure the initial rate of LPS transport (3.0 min-1 per LptDE). We also find that the rate of LPS transport by the Lpt complex is independent of the structure of LPS. In contrast, we find the rate of LPS transport is dependent on the proper function of the LptDE complex. Mutants of the outer membrane Lpt components, LptDE, that cause defective LPS assembly in live cells display attenuated transport rates and slower ATP hydrolysis compared to wild type proteins. Analysis of these mutants reveals that the rates of ATP hydrolysis and LPS transport are correlated such that 1.2 ± 0.2 ATP are hydrolyzed for each LPS transported. This correlation suggests a model where the outer membrane components ensure the coupling of ATP hydrolysis and LPS transport by stabilizing a transport-active state of the Lpt bridge.
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Affiliation(s)
| | | | - Rebecca J. Taylor
- Department of Chemistry and Chemical
Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Daniel Kahne
- Department of Chemistry and Chemical
Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Daniel G. Nocera
- Department of Chemistry and Chemical
Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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2
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Gomez-Sanchez CE, Gomez-Sanchez EP. Cholesterol Availability and Adrenal Steroidogenesis. Endocrinology 2024; 165:bqae032. [PMID: 38500355 PMCID: PMC10977269 DOI: 10.1210/endocr/bqae032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 03/15/2024] [Indexed: 03/20/2024]
Affiliation(s)
- Celso E Gomez-Sanchez
- Research and Medical Service, G. V. (Sonny) Montgomery VA Medical Center, Jackson, MS 39216, USA
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Elise P Gomez-Sanchez
- Research and Medical Service, G. V. (Sonny) Montgomery VA Medical Center, Jackson, MS 39216, USA
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216, USA
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3
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Liimatta J, Curschellas E, Altinkilic EM, Naamneh Elzenaty R, Augsburger P, du Toit T, Voegel CD, Breault DT, Flück CE, Pignatti E. Adrenal Abcg1 Controls Cholesterol Flux and Steroidogenesis. Endocrinology 2024; 165:bqae014. [PMID: 38301271 PMCID: PMC10863561 DOI: 10.1210/endocr/bqae014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/14/2024] [Accepted: 01/30/2024] [Indexed: 02/03/2024]
Abstract
Cholesterol is the precursor of all steroids, but how cholesterol flux is controlled in steroidogenic tissues is poorly understood. The cholesterol exporter ABCG1 is an essential component of the reverse cholesterol pathway and its global inactivation results in neutral lipid redistribution to tissue macrophages. The function of ABCG1 in steroidogenic tissues, however, has not been explored. To model this, we inactivated Abcg1 in the mouse adrenal cortex, which led to an adrenal-specific increase in transcripts involved in cholesterol uptake and de novo synthesis. Abcg1 inactivation did not affect adrenal cholesterol content, zonation, or serum lipid profile. Instead, we observed a moderate increase in corticosterone production that was not recapitulated by the inactivation of the functionally similar cholesterol exporter Abca1. Altogether, our data imply that Abcg1 controls cholesterol uptake and biosynthesis and regulates glucocorticoid production in the adrenal cortex, introducing the possibility that ABCG1 variants may account for physiological or subclinical variation in stress response.
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Affiliation(s)
- Jani Liimatta
- Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, Bern 3010, Switzerland
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
- Kuopio Pediatric Research Unit (KuPRU), University of Eastern Finland and Kuopio University Hospital, Kuopio 70200, Finland
| | - Evelyn Curschellas
- Department of Chemistry, Biochemistry and Pharmacy, Medical Faculty, University of Bern, Bern 3010, Switzerland
| | - Emre Murat Altinkilic
- Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, Bern 3010, Switzerland
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
| | - Rawda Naamneh Elzenaty
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
| | - Philipp Augsburger
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
| | - Therina du Toit
- Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, Bern 3010, Switzerland
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland
| | - Clarissa D Voegel
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland
| | - David T Breault
- Department of Pediatrics, Harvard Medical School, Boston Children's Hospital, Boston, MA 02115, USA
- Harvard Stem Cell Institute, Cambridge, MA 02138, USA
| | - Christa E Flück
- Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, Bern 3010, Switzerland
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
| | - Emanuele Pignatti
- Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, Bern University Hospital, Bern 3010, Switzerland
- Department for BioMedical Research, University Hospital Inselspital, University of Bern, Bern 3010, Switzerland
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4
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Azhar S, Shen WJ, Hu Z, Kraemer FB. MicroRNA regulation of adrenal glucocorticoid and androgen biosynthesis. VITAMINS AND HORMONES 2023; 124:1-37. [PMID: 38408797 DOI: 10.1016/bs.vh.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Steroid hormones are derived from a common precursor molecule, cholesterol, and regulate a wide range of physiologic function including reproduction, salt balance, maintenance of secondary sexual characteristics, response to stress, neuronal function, and various metabolic processes. Among the steroids synthesized by the adrenal and gonadal tissues, adrenal mineralocorticoids, and glucocorticoids are essential for life. The process of steroidogenesis is regulated at multiple levels largely by transcriptional, posttranscriptional, translational, and posttranslational regulation of the steroidogenic enzymes (i.e., cytochrome P450s and hydroxysteroid dehydrogenases), cellular compartmentalization of the steroidogenic enzymes, and cholesterol processing and transport proteins. In recent years, small noncoding RNAs, termed microRNAs (miRNAs) have been recognized as major post-transcriptional regulators of gene expression with essential roles in numerous biological processes and disease pathologies. Although their role in the regulation of steroidogenesis is still emerging, several recent studies have contributed significantly to our understanding of the role miRNAs play in the regulation of the steroidogenic process. This chapter focuses on the recent developments in miRNA regulation of adrenal glucocorticoid and androgen production in humans and rodents.
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Affiliation(s)
- Salman Azhar
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA, United States; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, United States; Stanford Diabetes Research Center, Stanford, CA, United States.
| | - Wen-Jun Shen
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA, United States; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, United States
| | - Zhigang Hu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology and College of Life Sciences, Nanjing Normal University, Nanjing, P.R. China
| | - Fredric B Kraemer
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA, United States; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, United States; Stanford Diabetes Research Center, Stanford, CA, United States
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5
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Sidhu SK, Mishra S. A cholesterol-centric outlook on steroidogenesis. VITAMINS AND HORMONES 2023; 124:405-428. [PMID: 38408806 DOI: 10.1016/bs.vh.2023.05.006] [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
Cholesterol, an essential and versatile lipid, is the precursor substrate for the biosynthesis of steroid hormones, and a key structural and functional component of organelle membranes in eukaryotic cells. Consequently, the framework of steroidogenesis across main steroidogenic cell types is built around cholesterol, including its cellular uptake, mobilization from intracellular storage, and finally, its transport to the mitochondria where steroidogenesis begins. This setup, which is controlled by different trophic hormones in their respective target tissues, allows steroidogenic cells to meet their steroidogenic need of cholesterol effectively without impinging on the basic need for organelle membranes and their functions. However, our understanding of the basal steroidogenesis (i.e., independent of trophic hormone stimulation), which is a cell-intrinsic trait, remains poor. Particularly, the role that cholesterol itself plays in the regulation of steroidogenic factors and events in steroid hormone-producing cells remains largely unexplored. This is likely because of challenges in selectively targeting the steroidogenic intracellular cholesterol pool in studies. New evidence suggests that cholesterol plays a role in steroidogenesis. These new findings have created new opportunities to advance our understanding in this field. In this book chapter, we will provide a cholesterol-centric view on steroidogenesis and emphasize the importance of the interplay between cholesterol and the mitochondria in steroidogenic cells. Moreover, we will discuss a novel mitochondrial player, prohibitin-1, in this context. The overall goal is to provide a stimulating perspective on cholesterol as an important regulator of steroidogenesis (i.e., more than just a substrate for steroid hormones) and present the mitochondria as a potential cell-intrinsic factor in regulating steroidogenic cholesterol homeostasis.
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Affiliation(s)
- Simarjit Kaur Sidhu
- Department of Physiology & Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Suresh Mishra
- Department of Physiology & Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada; Department of Internal Medicine, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
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6
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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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7
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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: 5] [Impact Index Per Article: 1.7] [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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8
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Aboubakr M, Abdelkader A, Habotta OA, Adel N, Emam MA, Abdelhiee EY, Shanab O, Shoghy K, Elnoury H, Soliman MM, Ibrahim SF, Abdeen A. Cefepime and diclofenac sodium combined treatment-potentiated multiple organ injury: Role of oxidative damage and disrupted lipid metabolism. J Biochem Mol Toxicol 2021; 35:e22929. [PMID: 34676623 DOI: 10.1002/jbt.22929] [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: 02/02/2021] [Revised: 07/16/2021] [Accepted: 10/06/2021] [Indexed: 11/09/2022]
Abstract
Concurrent exposure to antimicrobial and nonsteroidal anti-inflammatory drugs (NSAIDs) is usually inevitable in most infections and postsurgery. Consequently, the present study was designed to assess the intertwining impact of coadministration of cefepime (CP, a wide spectrum antibiotic) and diclofenac sodium (DF, an NSAID) on rat's liver, kidney, and testes. Rats received saline, CP (180 mg/kg/day, IM), DF (10 mg/kg/day, IM), or a combination of CP and DF. After 14 days, CP or DF induced tissue damage expressed by marked biochemical alterations in hepatic and renal function tests. Besides this, disrupted lipid metabolism and testosterone levels along with significant histological changes in hepatic, renal, and testicular tissues were noticed. A significant increase in malondialdehyde and decreases in superoxide dismutase and catalase activities alongside significant upregulated caspase 3 expression in tissues following CP or DF treatment suggested a bearable influence of oxidative stress, lipid peroxidation, and cell death. Accordingly, the simultaneous therapy of CP and DF evoked more obvious tissue damage than their individual treatment. Overall, data concluded that concurrent use of CP and DF in medical practice is a worrisome matter, so it should be done cautiously to avoid synergistic deleterious outcomes.
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Affiliation(s)
- Mohamed Aboubakr
- Department of Pharmacology, Faculty of Veterinary Medicine, Benha University, Toukh, Egypt
| | - Afaf Abdelkader
- Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Benha University, Benha, Egypt.,Center of Excellence for Screening of Environmental Contaminants (CESEC), Faculty of Veterinary Medicine, Benha University, Toukh, Egypt
| | - Ola A Habotta
- Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Nisreen Adel
- Department of Pharmacology, Faculty of Veterinary Medicine, Benha University, Toukh, Egypt
| | - Mahmoud A Emam
- Histology Department, Faculty of Veterinary Medicine, Benha University, Toukh, Egypt
| | - Ehab Y Abdelhiee
- Forensic Medicine and Toxicology Department, Faculty of Veterinary Medicine, Matrouh University, Matrouh, Egypt
| | - Obeid Shanab
- Biochemistry Department, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt
| | - Khaled Shoghy
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt
| | - Heba Elnoury
- Department of Pharmacology, Faculty of Medicine, Benha University, Benha, Egypt
| | - Mohamed M Soliman
- Clinical Laboratory Sciences Department, Turabah University College, Taif University, Taif, Saudi Arabia
| | - Samah F Ibrahim
- Clinical Sciences Department, College of Medicine, Princess Nourah bint Abdul Rahman University, Riyadh, Saudi Arabia.,Forensic Medicine and Clinical Toxicology Department, College of Medicine, Cairo University, Cairo, Egypt
| | - Ahmed Abdeen
- Center of Excellence for Screening of Environmental Contaminants (CESEC), Faculty of Veterinary Medicine, Benha University, Toukh, Egypt.,Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Benha University, Toukh, Egypt
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9
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Juhl AD, Heegaard CW, Werner S, Schneider G, Krishnan K, Covey DF, Wüstner D. Quantitative imaging of membrane contact sites for sterol transfer between endo-lysosomes and mitochondria in living cells. Sci Rep 2021; 11:8927. [PMID: 33903617 PMCID: PMC8076251 DOI: 10.1038/s41598-021-87876-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/31/2021] [Indexed: 01/25/2023] Open
Abstract
Mitochondria receive cholesterol from late endosomes and lysosomes (LE/LYSs) or from the plasma membrane for production of oxysterols and steroid hormones. This process depends on the endo-lysosomal sterol transfer protein Niemann Pick C2 (NPC2). Using the intrinsically fluorescent cholesterol analog, cholestatrienol, we directly observe sterol transport to mitochondria in fibroblasts upon treating NPC2 deficient human fibroblasts with NPC2 protein. Soft X-ray tomography reveals the ultrastructure of mitochondria and discloses close contact to endosome-like organelles. Using fluorescence microscopy, we localize endo-lysosomes containing NPC2 relative to mitochondria based on the Euclidian distance transform and use statistical inference to show that about 30% of such LE/LYSs are in contact to mitochondria in human fibroblasts. Using Markov Chain Monte Carlo image simulations, we show that interaction between both organelle types, a defining feature of membrane contact sites (MCSs) can give rise to the observed spatial organelle distribution. We devise a protocol to determine the surface fraction of endo-lysosomes in contact with mitochondria and show that this fraction does not depend on functional NPC1 or NPC2 proteins. Finally, we localize MCSs between LE/LYSs containing NPC2 and mitochondria in time-lapse image sequences and show that they either form transiently or remain stable for tens of seconds. Lasting MCSs between endo-lysosomes containing NPC2 and mitochondria move by slow anomalous sub-diffusion, providing location and time for sterol transport between both organelles. Our quantitative imaging strategy will be of high value for characterizing the dynamics and function of MCSs between various organelles in living cells.
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Affiliation(s)
- Alice Dupont Juhl
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Christian W Heegaard
- Department of Molecular Biology and Genetics, University of Aarhus, 8000, Aarhus C, Denmark
| | - Stephan Werner
- Department of X-Ray Microscopy, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany
| | - Gerd Schneider
- Department of X-Ray Microscopy, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University, St. Louis, MO, 63110, USA
| | - Douglas F Covey
- Department of Developmental Biology, Washington University, St. Louis, MO, 63110, USA
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
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10
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Dynamic Remodeling of Membranes and Their Lipids during Acute Hormone-Induced Steroidogenesis in MA-10 Mouse Leydig Tumor Cells. Int J Mol Sci 2021; 22:ijms22052554. [PMID: 33806352 PMCID: PMC7961408 DOI: 10.3390/ijms22052554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 02/24/2021] [Accepted: 02/27/2021] [Indexed: 12/14/2022] Open
Abstract
Lipids play essential roles in numerous cellular processes, including membrane remodeling, signal transduction, the modulation of hormone activity, and steroidogenesis. We chose steroidogenic MA-10 mouse tumor Leydig cells to investigate subcellular lipid localization during steroidogenesis. Electron microscopy showed that cAMP stimulation increased associations between the plasma membrane (PM) and the endoplasmic reticulum (ER) and between the ER and mitochondria. cAMP stimulation also increased the movement of cholesterol from the PM compared to untreated cells, which was partially inhibited when ATPase family AAA-domain containing protein 3 A (ATAD3A), which functions in ER and mitochondria interactions, was knocked down. Mitochondria, ER, cytoplasm, PM, PM-associated membranes (PAMs), and mitochondria-associated membranes (MAMs) were isolated from control and hormone-stimulated cells. Lipidomic analyses revealed that each isolated compartment had a unique lipid composition, and the induction of steroidogenesis caused the significant remodeling of its lipidome. cAMP-induced changes in lipid composition included an increase in phosphatidylserine and cardiolipin levels in PAM and PM compartments, respectively; an increase in phosphatidylinositol in the ER, mitochondria, and MAMs; and a reorganization of phosphatidic acid, cholesterol ester, ceramide, and phosphatidylethanolamine. Abundant lipids, such as phosphatidylcholine, were not affected by hormone treatment. Our data suggested that PM–ER–mitochondria tethering may be involved in lipid trafficking between organelles and indicated that hormone-induced acute steroid production involves extensive organelle remodeling.
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11
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Azhar S, Dong D, Shen WJ, Hu Z, Kraemer FB. The role of miRNAs in regulating adrenal and gonadal steroidogenesis. J Mol Endocrinol 2020; 64:R21-R43. [PMID: 31671401 PMCID: PMC7202133 DOI: 10.1530/jme-19-0105] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 10/29/2019] [Indexed: 12/13/2022]
Abstract
miRNAs are endogenous noncoding single-stranded small RNAs of ~22 nucleotides in length that post-transcriptionally repress the expression of their various target genes. They contribute to the regulation of a variety of physiologic processes including embryonic development, differentiation and proliferation, apoptosis, metabolism, hemostasis and inflammation. In addition, aberrant miRNA expression is implicated in the pathogenesis of numerous diseases including cancer, hepatitis, cardiovascular diseases and metabolic diseases. Steroid hormones regulate virtually every aspect of metabolism, and acute and chronic steroid hormone biosynthesis is primarily regulated by tissue-specific trophic hormones involving transcriptional and translational events. In addition, it is becoming increasingly clear that steroidogenic pathways are also subject to post-transcriptional and post-translational regulations including processes such as phosphorylation/dephosphorylation, protein‒protein interactions and regulation by specific miRNAs, although the latter is in its infancy state. Here, we summarize the recent advances in miRNA-mediated regulation of steroidogenesis with emphasis on adrenal and gonadal steroidogenesis.
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Affiliation(s)
- Salman Azhar
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, California, USA
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford University, Stanford, California, USA
- Stanford Diabetes Research Center, Stanford, California, USA
| | - Dachuan Dong
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, California, USA
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford University, Stanford, California, USA
| | - Wen-Jun Shen
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, California, USA
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford University, Stanford, California, USA
| | - Zhigang Hu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology and College of Life Science, Nanjing Normal University, Nanjing, China
| | - Fredric B Kraemer
- Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, California, USA
- Division of Endocrinology, Gerontology and Metabolism, Stanford University, Stanford University, Stanford, California, USA
- Stanford Diabetes Research Center, Stanford, California, USA
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Chung JY, Chen H, Papadopoulos V, Zirkin B. Cholesterol accumulation, lipid droplet formation, and steroid production in Leydig cells: Role of translocator protein (18-kDa). Andrology 2019; 8:719-730. [PMID: 31738001 DOI: 10.1111/andr.12733] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 11/06/2019] [Accepted: 11/14/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Cholesterol import into the mitochondria of steroid-producing cells is the rate-determining step in steroidogenesis. Numerous studies have provided evidence that the cholesterol-binding translocator protein (18 kDa TSPO) plays an important role in cholesterol translocation into mitochondria and that it also might act on cholesterol homeostasis. Several TSPO-specific ligands have been shown to increase steroid production in vitro and in vivo. OBJECTIVES The present study assessed the effects of the TSPO drug ligand FGIN-1-27 on cholesterol accumulation and lipid droplet formation in relationship to steroid formation. MATERIALS AND METHODS Using MA-10 and primary Leydig cells, immunocytochemical and molecular methods were used to examine cholesterol accumulation, the formation of lipid droplets, and steroid formation in response to LH and FGIN-1-27. Additionally, we determined the effects of Tspo knockout by CRISPR/Cas9, and of siRNA knockdowns of Tspo and Plin2 (Perilipin 2; also known as adipose differentiation-related protein, ADFP) on LH- and FGIN-1-27-induced steroidogenesis. RESULTS In response to LH and FGIN-1-27, cultured MA-10 cells and primary Leydig cells increased steroid formation, cholesterol accumulation, and lipid droplet formation. Cholesterol accumulation in the lipid droplets also was increased in Tspo knockout cells. Knockout of Tspo or its knockdown in MA-10 cells resulted in reduced progesterone formation in response to both LH and FGIN-1-27, as did knockdown of Plin2. Steroid production also was inhibited by the cholesteryl ester hydrolase inhibitor diethylumbelliferyl phosphate. DISCUSSION AND CONCLUSION These results support the conclusion that FGIN-1-27 stimulates steroid formation by increasing TSPO-mediated cholesterol translocation into the inner mitochondria for steroidogenesis, as well as into the cytosol for lipid droplet formation. FGIN-1-27 also increased steroid formation at least in part by inducing the conversion of cholesteryl ester located in lipid droplets to cholesterol, thus making available more substrate for steroid formation.
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Affiliation(s)
- Jin-Yong Chung
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Haolin Chen
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.,Department of Anesthesiology, the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Vassilios Papadopoulos
- Department of Pharmacology and Pharmaceutical Science, School of Pharmacy, University of Southern California, Los Angeles, CA, USA
| | - Barry Zirkin
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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