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Reinholdt P, Joensen LE, Petersen D, Szomek M, Mularski A, Simonsen AC, Kongsted J, Wüstner D. Photophysical and Structural Characterization of Intrinsically Fluorescent Sterol Aggregates. J Phys Chem B 2021; 125:5838-5852. [PMID: 34061522 DOI: 10.1021/acs.jpcb.1c00628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Self-association of cholesterol into aggregates and crystals is a hallmark of developing atherosclerosis. Intrinsically fluorescent sterols, such as dehydroergosterol (DHE), can be used to study sterol aggregation by fluorescence spectroscopy and microscopy, but a thorough understanding of DHE's photophysical and structural properties in the aggregated state is missing. Here, we show that DHE forms submicron fluorescent aggregates when evaporated from an ethanol solution. Using atomic force microscopy, we find that DHE, like cholesterol, forms compact oblate-shape aggregates of <100 nm in diameter. DHE's fluorescence is lowered in the aggregate compared to the monomeric form, and characteristic spectral changes accompany the aggregation process. Electronic structure calculations of DHE dimers in water indicate that Frenkel-type exciton coupling contributes to the lowered DHE fluorescence in the aggregates. Using molecular dynamics (MD) simulations, we show that DHE forms compact aggregates on the nanosecond scale and with strong intermolecular attraction, in which a broad range of orientations, and therefore electronic couplings, will take place. Tight packing of DHE in aggregates also lowers the apparent absorption cross section, further reducing the molecular brightness of the aggregates. Our results pave the way for systematic solubility studies of intrinsically fluorescent analogues of biologically relevant sterols.
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Affiliation(s)
- Peter Reinholdt
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Lütje E Joensen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Daniel Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Maria Szomek
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Anna Mularski
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Adam Cohen Simonsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Jacob Kongsted
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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Kuroi K, Imaizumi M, Miura T, Nakabayashi T. Examination of the association states of dehydroergosterol towards understanding the association structures of sterols in a membrane. Biochem Biophys Res Commun 2019; 515:228-233. [PMID: 31146916 DOI: 10.1016/j.bbrc.2019.05.109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 05/16/2019] [Indexed: 10/26/2022]
Abstract
Cholesterol plays a number of roles in cell membranes, and dehydroergosterol (DHE) is a fluorescent derivative of cholesterol, which is used to investigate the association structure of cholesterol. Although the fluorescent property of DHE depends on its association state, it is insufficient to distinguish the association state of DHE only by its fluorescence. Circular dichroism (CD) spectroscopy is an effective way to investigate the molecular geometry of DHE. In the present study, therefore we investigated the association structure of DHE by CD and fluorescence spectroscopy in solution and in a lipid membrane. DHE was shown to exist as three states (monomeric, microcrystalline, and micelle states) in methanol-water mixtures depending on solvent hydrophobicity. The CD spectrum of DHE in a liposome was similar to that of the micelle state, indicating that the association state of DHE in a liposome exhibits a parallel arrangement similar to that in the micelle state. This result is difficult to be obtained only from the measurement of the fluorescence spectra. The combination of CD and fluorescence spectroscopic techniques is necessary to investigate the association of DHE.
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Affiliation(s)
- Kunisato Kuroi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Masatomo Imaizumi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Takashi Miura
- Department of Pharmaceutical Sciences, International University of Health and Welfare, 2600-1 Kitakanemaru, Ohtawara, Tochigi, 324-8501, Japan.
| | - Takakazu Nakabayashi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan.
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Martínez-Montemayor MM, Ling T, Suárez-Arroyo IJ, Ortiz-Soto G, Santiago-Negrón CL, Lacourt-Ventura MY, Valentín-Acevedo A, Lang WH, Rivas F. Identification of Biologically Active Ganoderma lucidum Compounds and Synthesis of Improved Derivatives That Confer Anti-cancer Activities in vitro. Front Pharmacol 2019; 10:115. [PMID: 30837881 PMCID: PMC6389703 DOI: 10.3389/fphar.2019.00115] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/30/2019] [Indexed: 01/01/2023] Open
Abstract
We previously reported that Ganoderma lucidum extract (GLE) demonstrate significant anti-cancer activity against triple negative inflammatory breast cancer models. Herein, we aimed to elucidate the bioactive compounds of GLE responsible for this anti-cancer activity. We performed NMR, X-ray crystallography and analog derivatization as well as anti-cancer activity studies to elucidate and test the compounds. We report the structures of the seven most abundant GLE compounds and their selective efficacy against triple negative (TNBC) and inflammatory breast cancers (IBC) and other human cancer cell types (solid and blood malignancies) to illustrate their potential as anti-cancer agents. Three of the seven compounds (ergosterol, 5,6-dehydroergosterol and ergosterol peroxide) exhibited significant in vitro anti-cancer activities, while we report for the first time the structure elucidation of 5,6-dehydroergosterol from Ganoderma lucidum. We also show for the first time in TNBC/IBC cells that ergosterol peroxide (EP) displays anti-proliferative effects through G1 phase cell cycle arrest, apoptosis induction via caspase 3/7 activation, and PARP cleavage. EP decreased migratory and invasive effects of cancer cells while inhibiting the expression of total AKT1, AKT2, BCL-XL, Cyclin D1 and c-Myc in the tested IBC cells. Our investigation also indicates that these compounds induce reactive oxygen species, compromising cell fate. Furthermore, we generated a superior derivative, ergosterol peroxide sulfonamide, with improved potency in IBC cells and ample therapeutic index (TI > 10) compared to normal cells. The combined studies indicate that EP from Ganoderma lucidum extract is a promising molecular scaffold for further exploration as an anti-cancer agent.
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Affiliation(s)
| | - Taotao Ling
- Department of Chemical Biology & Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Ivette J. Suárez-Arroyo
- Cancer Research Unit, Department of Biochemistry, School of Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico
| | - Gabriela Ortiz-Soto
- Cancer Research Unit, Department of Biochemistry, School of Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico
| | | | - Mercedes Y. Lacourt-Ventura
- Cancer Research Unit, Department of Biochemistry, School of Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico
| | - Anibal Valentín-Acevedo
- Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico
| | - Walter H. Lang
- Department of Chemical Biology & Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Fatima Rivas
- Department of Chemical Biology & Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN, United States
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Schroeder F, Huang H, McIntosh AL, Atshaves BP, Martin GG, Kier AB. Caveolin, sterol carrier protein-2, membrane cholesterol-rich microdomains and intracellular cholesterol trafficking. Subcell Biochem 2010; 51:279-318. [PMID: 20213548 DOI: 10.1007/978-90-481-8622-8_10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
While the existence of membrane lateral microdomains has been known for over 30 years, interest in these structures accelerated in the past decade due to the discovery that cholesterol-rich microdomains serve important biological functions. It is increasingly appreciated that cholesterol-rich microdomains in the plasma membranes of eukaryotic cells represent an organizing nexus for multiple cellular proteins involved in transmembrane nutrient uptake (cholesterol, fatty acid, glucose, etc.), cell-signaling, immune recognition, pathogen entry, and many other roles. Despite these advances, however, relatively little is known regarding the organization of cholesterol itself in these plasma membrane microdomains. Although a variety of non-sterol markers indicate the presence of microdomains in the plasma membranes of living cells, none of these studies have demonstrated that cholesterol is enriched in these microdomains in living cells. Further, the role of cholesterol-rich membrane microdomains as targets for intracellular cholesterol trafficking proteins such as sterol carrier protein-2 (SCP-2) that facilitate cholesterol uptake and transcellular transport for targeting storage (cholesterol esters) or efflux is only beginning to be understood. Herein, we summarize the background as well as recent progress in this field that has advanced our understanding of these issues.
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Affiliation(s)
- Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC College Station, TX, 77843-4466, USA.
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