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Kim J, Kim MY, Han Y, Lee GY, Kim DH, Heo YJ, Park M. Development of an electrochemical biosensor for non-invasive cholesterol monitoring via microneedle-based interstitial fluid extraction. Talanta 2024; 280:126771. [PMID: 39191110 DOI: 10.1016/j.talanta.2024.126771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 08/09/2024] [Accepted: 08/24/2024] [Indexed: 08/29/2024]
Abstract
In this study, we present the development of an innovative electrochemical biosensor integrated into a microneedle-based system for non-invasive and sensitive quantification of cholesterol levels in interstitial fluid (ISF). The biosensor employs a graphene-based electrode with a polyelectrolyte interlayer to immobilize cholesterol oxidase (ChOx), enabling selective cholesterol detection. Graphene oxide is electrochemically reduced to form a conductive layer, and PANI is chosen as the optimal polyelectrolyte for ChOx immobilization. The biosensor's performance is thoroughly evaluated, demonstrating excellent sensitivity, stability, and selectivity. Furthermore, the biosensor is successfully applied to skin-mimicking agarose gel and porcine skin, showcasing its potential for real-world interstitial fluid extraction and cholesterol monitoring. The integrated microneedle-based system offers a promising approach for non-invasive monitoring of cholesterol levels, with implications for personalized healthcare diagnostics.
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Affiliation(s)
- JeeYoung Kim
- Major in Materials Science and Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Integrative Materials Research Institute, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Interdisciplinary Program of Nano-Medical Device Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea
| | - Mi Yeon Kim
- Major in Materials Science and Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Integrative Materials Research Institute, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Interdisciplinary Program of Nano-Medical Device Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea
| | - Yuna Han
- Department of Mechanical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do, 17104, Republic of Korea; Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do, 17104, Republic of Korea
| | - Ga Yeong Lee
- Department of Mechanical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do, 17104, Republic of Korea; Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do, 17104, Republic of Korea
| | - Da Hyeon Kim
- Major in Materials Science and Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Integrative Materials Research Institute, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Interdisciplinary Program of Nano-Medical Device Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea
| | - Yun Jung Heo
- Department of Mechanical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do, 17104, Republic of Korea; Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do, 17104, Republic of Korea.
| | - Min Park
- Major in Materials Science and Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Integrative Materials Research Institute, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea; Interdisciplinary Program of Nano-Medical Device Engineering, Hallym University, 1 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 24252, Republic of Korea.
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Bellos I, Lagiou P, Benetou V, Marinaki S. Efficacy and safety of statin therapy in kidney transplant recipients: a systematic review and meta-analysis. Lipids Health Dis 2024; 23:293. [PMID: 39261803 PMCID: PMC11389595 DOI: 10.1186/s12944-024-02276-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Accepted: 08/28/2024] [Indexed: 09/13/2024] Open
Abstract
BACKGROUND Dyslipidemia represents an important risk factor for cardiovascular diseases, although its optimal management after kidney transplantation remains unclear. The present meta-analysis aimed to shed light on the efficacy and safety of statins among kidney transplant recipients, evaluating their potential effects on the risk of cardiovascular events, mortality and graft survival. METHODS Medline, Scopus, Web of Science, CENTRAL, Clinicaltrials.gov and Google Scholar were systematically searched from their inception through April 20, 2024. Both randomized controlled trials and observational studies evaluating the effects of statin administration after kidney transplantation were held eligible. Random-effects models were fitted using the maximum likelihood method, while the certainty of evidence was appraised following the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) approach. RESULTS Overall, 27 studies (10 randomized controlled trials and 17 observational studies) were included. Statin use compared to no use was associated with a lower risk of major adverse cardiovascular events [Relative risk (RR): 0.87, 95% confidence interval (CI): 0.67-0.96, moderate certainty] and overall mortality (RR: 0.84, 95% CI: 0.74-0.94, low certainty). The risk of graft loss did not differ between the compared groups (RR: 0.72, 95% CI: 0.48-1.08, very low certainty). Regarding safety endpoints, statin use was associated with a lower risk of hepatotoxicity (RR: 0.81, 95% CI: 0.70-0.93, moderate certainty), but with a greater risk of rhabdomyolysis (RR: 1.37, 95% CI: 1.10-1.70, low certainty) and cataract (RR: 1.22, 95% CI: 1.14-1.31, moderate certainty). No statistically significant differences between the compared groups with and without statin use were observed concerning the risk of creatine kinase elevation, post-transplant diabetes mellitus, hip fracture, venous thromboembolism, or cancer. CONCLUSIONS Among kidney transplant recipients, statin use is associated with a lower risk of cardiovascular events and better patient survival, presenting an acceptable safety profile. Further large-scale studies are needed to determine the optimal statin dosing strategy and lipid-lowering goals, depending on comorbidities and immunosuppression regimens. REGISTRATION https://doi.org/10.17504/protocols.io.5qpvok3yzl4o/v1 .
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Affiliation(s)
- Ioannis Bellos
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias str, Athens, 115 27, Greece.
- Department of Nephrology and Renal Transplantation, Laiko General Hospital, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias str, Athens, 115 27, Greece.
| | - Pagona Lagiou
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias str, Athens, 115 27, Greece
| | - Vassiliki Benetou
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias str, Athens, 115 27, Greece
| | - Smaragdi Marinaki
- Department of Nephrology and Renal Transplantation, Laiko General Hospital, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias str, Athens, 115 27, Greece
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Cheng C. Tissue, cellular, and molecular level determinants for eye lens stiffness and elasticity. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1456474. [PMID: 39176256 PMCID: PMC11339033 DOI: 10.3389/fopht.2024.1456474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 07/26/2024] [Indexed: 08/24/2024]
Abstract
The eye lens is a transparent, ellipsoid tissue in the anterior chamber that is required for the fine focusing of light onto the retina to transmit a clear image. The focusing function of the lens is tied to tissue transparency, refractive index, and biomechanical properties. The stiffness and elasticity or resilience of the human lens allows for shape changes during accommodation to focus light from objects near and far. It has long been hypothesized that changes in lens biomechanical properties with age lead to the loss of accommodative ability and the need for reading glasses with age. However, the cellular and molecular mechanisms that influence lens biomechanical properties and/or change with age remain unclear. Studies of lens stiffness and resilience in mouse models with genetic defects or at advanced age inform us of the cytoskeletal, structural, and morphometric parameters that are important for biomechanical stability. In this review, we will explore whether: 1) tissue level changes, including the capsule, lens volume, and nucleus volume, 2) cellular level alterations, including cell packing, suture organization, and complex membrane interdigitations, and 3) molecular scale modifications, including the F-actin and intermediate filament networks, protein modifications, lipids in the cell membrane, and hydrostatic pressure, influence overall lens biomechanical properties.
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Affiliation(s)
- Catherine Cheng
- School of Optometry and Vision Science Program, Indiana University, Bloomington, IN, United States
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Halili A, Haxha S, Zareini B, Lund-Andersen C, Kold Sørensen K, Torp-Pedersen C, Eroglu TE, Bang CN. Association between long-term statin use and cataract surgery: a nationwide study on 505 105 cataract surgery patients. Br J Ophthalmol 2024:bjo-2022-322409. [PMID: 39054053 DOI: 10.1136/bjo-2022-322409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 07/14/2024] [Indexed: 07/27/2024]
Abstract
AIMS To assess the association between statin use and cataract surgery according to different statin treatment durations in patients with different cardiovascular risk profiles. METHODS AND RESULTS We performed a nested case-control study using Danish registries, covering the period from 1 January 1996 to 31 December 2020. We defined cases as surgically treated cataract patients, matched in a 1:1 ratio by sex and age with controls not undergoing cataract surgery. The exposure of interest was statin use in different durations (1, 5 and 10 years) compared with never use of statins. Conditional logistic regression provided adjusted HRs and corresponding 95% CIs in subgroups defined by established atherosclerotic cardiovascular disease, diabetes, hypertension and individuals without these comorbidities. We identified 505 150 cataract surgery cases and found no increased HR of cataract surgery with statin treatment at any duration in any of the subgroups with established atherosclerotic cardiovascular disease, diabetes or hypertension. CONCLUSION Our findings do not support a possible association between long-term statin use and cataract in patients with established atherosclerotic cardiovascular disease, diabetes or hypertension. Although we found an association between statin use and cataract in individuals without these comorbidities, increasing durations of statin use did not yield higher cataract surgery rates.
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Affiliation(s)
- Andrim Halili
- Cardiology, Bispebjerg Hospital, Koebenhavn, Denmark
- Cardiology, North Zealand Hospital, Hilleroed, Denmark
| | - Saranda Haxha
- Cardiology, Bispebjerg Hospital, Koebenhavn, Denmark
- Cardiology, North Zealand Hospital, Hilleroed, Denmark
| | - Bochra Zareini
- Cardiology, North Zealand Hospital, Hilleroed, Denmark
- Public Health, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Christian Torp-Pedersen
- Cardiology, North Zealand Hospital, Hilleroed, Denmark
- Public Health, University of Copenhagen, Copenhagen, Denmark
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Shu X, Liu Y, He F, Gong Y, Li J. A bibliometric and visualized analysis of the pathogenesis of cataracts from 1999 to 2023. Heliyon 2024; 10:e26044. [PMID: 38390089 PMCID: PMC10881887 DOI: 10.1016/j.heliyon.2024.e26044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 02/24/2024] Open
Abstract
Research on the pathogenesis of cataracts is ongoing and the number of publications on this topic is increasing annually. This study offers an overview of the research status, popular topics, and scholarly tendencies in the field of cataract pathogenesis over recent decades,which helps to guide future research directions, and optimize resource allocation. In the present study, we performed a bibliometric analysis of cataract pathogenesis. Publications from January 1, 1999, to December 20, 2023, were collected from the Web of Science Core Collection (WoSCC), and the extracted data were quantified and analyzed. We analyzed and presented the data using Microsoft Excel, VOSviewer, CiteSpace, and Python. In all, 4006 articles were evaluated based on various characteristics, including publication year, authors, countries, institutions, journals, citations, and keywords. This study utilized VOSviewer to conduct visualized analysis, including co-authorship, co-citation, co-occurrence, and network visualization. The CiteSpace software was used to identify keywords with significant bursts of activity. The number of annual global publications climbed from 76 to 277 between 1999 and 2023, a 264.47% rise. Experimental Eye Research published the most manuscripts (178 publications), whereas Investigative Ophthalmology & Visual Science received the most citations (6675 citations). The most influential and productive country, institution, and author were the United States (1244 publications, 54,456 citations), University of California system (136 publications, 5401 citations), and Yao Ke (49 publications, 838 citations), respectively. The top 100 ranked keywords are divided into four clusters through co-occurrence analysis: (1) secondary cataracts, (2) oxidative stress, (3) gene mutations and protein abnormalities, and (4) alteration of biological processes in lens epithelial cells. Further discussions on the four subtopics outline the research topics and trends. In conclusion, the specific mechanism of cataract formation remains a popular topic for future research and should be explored in greater depth.
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Affiliation(s)
- Xinjie Shu
- Department of Ophthalmology, Medical Sciences Research Center, University-Town Hospital of Chongqing Medical University, No. 55, University Town Central Road, Shapingba District, Chongqing, 401331, People's Republic of China
| | - Yingying Liu
- Department of Ophthalmology, Medical Sciences Research Center, University-Town Hospital of Chongqing Medical University, No. 55, University Town Central Road, Shapingba District, Chongqing, 401331, People's Republic of China
| | - Fanfan He
- Department of Ophthalmology, Medical Sciences Research Center, University-Town Hospital of Chongqing Medical University, No. 55, University Town Central Road, Shapingba District, Chongqing, 401331, People's Republic of China
| | - Yu Gong
- Department of Ophthalmology, Medical Sciences Research Center, University-Town Hospital of Chongqing Medical University, No. 55, University Town Central Road, Shapingba District, Chongqing, 401331, People's Republic of China
| | - Jiawen Li
- Department of Ophthalmology, Medical Sciences Research Center, University-Town Hospital of Chongqing Medical University, No. 55, University Town Central Road, Shapingba District, Chongqing, 401331, People's Republic of China
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Hazen P, Trossi-Torres G, Timsina R, Khadka NK, Mainali L. Association of Alpha-Crystallin with Human Cortical and Nuclear Lens Lipid Membrane Increases with the Grade of Cortical and Nuclear Cataract. Int J Mol Sci 2024; 25:1936. [PMID: 38339214 PMCID: PMC10855980 DOI: 10.3390/ijms25031936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/29/2024] [Accepted: 02/03/2024] [Indexed: 02/12/2024] Open
Abstract
Eye lens α-crystallin has been shown to become increasingly membrane-bound with age and cataract formation; however, to our knowledge, no studies have investigated the membrane interactions of α-crystallin throughout the development of cataracts in separated cortical membrane (CM) and nuclear membrane (NM) from single human lenses. In this study, four pairs of human lenses from age-matched male and female donors and one pair of male lenses ranging in age from 64 to 73 years old (yo) were obtained to investigate the interactions of α-crystallin with the NM and CM throughout the progression of cortical cataract (CC) and nuclear cataract (NC) using the electron paramagnetic resonance spin-labeling method. Donor health history information (diabetes, smoker, hypertension, radiation treatment), sex, and race were included in the data analysis. The right eye lenses CM and NM investigated were 64 yo male (CC: 0), 68 yo male (CC: 3, NC: 2), 73 yo male (CC: 1, NC: 2), 68 yo female (CC: 3, NC: 2), and 73 yo female (CC: 1, NC: 3). Similarly, left eye lenses CM and NM investigated were 64 yo male (CC: 0), 68 yo male (CC: 3, NC: 2), 73 yo male (CC: 2, NC: 3), 68 yo female (CC: 3, NC: 2), and 73 yo female (CC: 1, NC: 3). Analysis of α-crystallin binding to male and female eye lens CM and NM revealed that the percentage of membrane surface occupied (MSO) by α-crystallin increases with increasing grade of CC and NC. The binding of α-crystallin resulted in decreased mobility, increased order, and increased hydrophobicity on the membrane surface in male and female eye lens CM and NM. CM mobility decreased with an increase in cataracts for both males and females, whereas the male lens NM mobility showed no significant change, while female lens NM showed increased mobility with an increase in cataract grade. Our data shows that a 68 yo female donor (long-term smoker, pre-diabetic, and hypertension; grade 3 CC) showed the largest MSO by α-crystallin in CM from both the left and right lens and had the most pronounced mobility changes relative to all other analyzed samples. The variation in cholesterol (Chol) content, size and amount of cholesterol bilayer domains (CBDs), and lipid composition in the CM and NM with age and cataract might result in a variation of membrane surface mobility, membrane surface hydrophobicity, and the interactions of α-crystallin at the surface of each CM and NM. These findings provide insight into the effect of decreased Chol content and the reduced size and amount of CBDs in the cataractous CM and NM with an increased binding of α-crystallin with increased CC and NC grade, which suggests that Chol and CBDs might be a key component in maintaining lens transparency.
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Affiliation(s)
- Preston Hazen
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.)
| | - Geraline Trossi-Torres
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.)
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
| | - Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
| | - Nawal K. Khadka
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
| | - Laxman Mainali
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.)
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
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Timsina R, Hazen P, Trossi-Torres G, Khadka NK, Kalkat N, Mainali L. Cholesterol Content Regulates the Interaction of αA-, αB-, and α-Crystallin with the Model of Human Lens-Lipid Membranes. Int J Mol Sci 2024; 25:1923. [PMID: 38339200 PMCID: PMC10855794 DOI: 10.3390/ijms25031923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/28/2024] [Accepted: 02/03/2024] [Indexed: 02/12/2024] Open
Abstract
α-Crystallin (αABc) is a major protein comprised of αA-crystallin (αAc) and αB-crystallin (αBc) that is found in the human eye lens and works as a molecular chaperone by preventing the aggregation of proteins and providing tolerance to stress. However, with age and cataract formation, the concentration of αABc in the eye lens cytoplasm decreases, with a corresponding increase in the membrane-bound αABc. This study uses the electron paramagnetic resonance (EPR) spin-labeling method to investigate the role of cholesterol (Chol) and Chol bilayer domains (CBDs) in the binding of αAc, αBc, and αABc to the Chol/model of human lens-lipid (Chol/MHLL) membranes. The maximum percentage of membrane surface occupied (MMSO) by αAc, αBc, and αABc to Chol/MHLL membranes at a mixing ratio of 0 followed the trends: MMSO (αAc) > MMSO (αBc) ≈ MMSO (αABc), indicating that a higher amount of αAc binds to these membranes compared to αBc and αABc. However, with an increase in the Chol concentration in the Chol/MHLL membranes, the MMSO by αAc, αBc, and αABc decreases until it is completely diminished at a mixing ratio of 1.5. The Ka of αAc, αBc, and αABc to Chol/MHLL membranes at a mixing ratio of 0 followed the trend: Ka (αBc) ≈ Ka (αABc) > Ka (αAc), but it was close to zero with the diminished binding at a Chol/MHLL mixing ratio of 1.5. The mobility near the membrane headgroup regions decreased with αAc, αBc, and αABc binding, and the Chol antagonized the capacity of the αAc, αBc, and αABc to decrease mobility near the headgroup regions. No significant change in membrane order near the headgroup regions was observed, with an increase in αAc, αBc, and αABc concentrations. Our results show that αAc, αBc, and αABc bind differently with Chol/MHLL membranes at mixing ratios of 0 and 0.5, decreasing the mobility and increasing hydrophobicity near the membrane headgroup region, likely forming the hydrophobic barrier for the passage of polar and ionic molecules, including antioxidants (glutathione), creating an oxidative environment inside the lens, leading to the development of cataracts. However, all binding was completely diminished at a mixing ratio of 1.5, indicating that high Chol and CBDs inhibit the binding of αAc, αBc, and αABc to membranes, preventing the formation of hydrophobic barriers and likely protecting against cataract formation.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
| | - Preston Hazen
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.); (N.K.)
| | - Geraline Trossi-Torres
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.); (N.K.)
| | - Nawal K. Khadka
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
| | - Navdeep Kalkat
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.); (N.K.)
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID 83725, USA; (R.T.); (N.K.K.)
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.); (N.K.)
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Guo J, Chen S, Zhang Y, Liu J, Jiang L, Hu L, Yao K, Yu Y, Chen X. Cholesterol metabolism: physiological regulation and diseases. MedComm (Beijing) 2024; 5:e476. [PMID: 38405060 PMCID: PMC10893558 DOI: 10.1002/mco2.476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 02/27/2024] Open
Abstract
Cholesterol homeostasis is crucial for cellular and systemic function. The disorder of cholesterol metabolism not only accelerates the onset of cardiovascular disease (CVD) but is also the fundamental cause of other ailments. The regulation of cholesterol metabolism in the human is an extremely complex process. Due to the dynamic balance between cholesterol synthesis, intake, efflux and storage, cholesterol metabolism generally remains secure. Disruption of any of these links is likely to have adverse effects on the body. At present, increasing evidence suggests that abnormal cholesterol metabolism is closely related to various systemic diseases. However, the exact mechanism by which cholesterol metabolism contributes to disease pathogenesis remains unclear, and there are still unknown factors. In this review, we outline the metabolic process of cholesterol in the human body, especially reverse cholesterol transport (RCT). Then, we discuss separately the impact of abnormal cholesterol metabolism on common diseases and potential therapeutic targets for each disease, including CVD, tumors, neurological diseases, and immune system diseases. At the end of this review, we focus on the effect of cholesterol metabolism on eye diseases. In short, we hope to provide more new ideas for the pathogenesis and treatment of diseases from the perspective of cholesterol.
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Affiliation(s)
- Jiarui Guo
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Silong Chen
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Ying Zhang
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
- Institute of Translational MedicineZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Jinxia Liu
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Luyang Jiang
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Lidan Hu
- National Clinical Research Center for Child HealthThe Children's HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Ke Yao
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Yibo Yu
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Xiangjun Chen
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
- Institute of Translational MedicineZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
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Ma P, Huang J, Chen B, Huang M, Xiong L, Chen J, Huang S, Liu Y. Lanosterol Synthase Prevents EMT During Lens Epithelial Fibrosis Via Regulating SREBP1. Invest Ophthalmol Vis Sci 2023; 64:12. [PMID: 38079167 PMCID: PMC10715316 DOI: 10.1167/iovs.64.15.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/25/2023] [Indexed: 12/18/2023] Open
Abstract
Purpose Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a predominant pathological process underlying fibrotic cataracts. Here we investigated the role and mechanism of lanosterol synthase (LSS), a key rate-limiting enzyme in sterol biosynthesis, in EMT of LECs. Methods Human lens epithelial explants, primary rabbit LECs, and whole rat lenses were treated with TGFβ2. RNA-sequencing was conducted to explore genetic changes during fibrosis of human lens epithelial explants. Loss- and gain-of-function studies were performed in primary LECs to investigate roles and mechanisms of LSS, lanosterol and sterol regulatory element binding transcription protein 1 (SREBP1) in EMT. Rat lenses were applied to evaluate the potential effect of lanosterol on lens fibrosis. Expression of LSS, SREBP1, EMT-related regulators, and markers were analyzed by Western blot, qRT-PCR, or immunofluorescent staining. Results LSS and steroid biosynthesis were downregulated in TGFβ2-induced lens fibrosis. LSS inhibition directly triggered EMT by inducing Smad2/3 phosphorylation and nucleus translocation, an overexpression of LSS protected LECs from EMT by inhibiting Smad2/3 activation. Moreover, LSS inhibition decreased the expression of SREBP1, which regulated EMT via intervening TGFβ2/Smad2/3 transduction. Furthermore, lanosterol protected LECs from EMT caused by both TGFβ2 treatment and LSS inhibition via suppressing Smad2/3 activation and maintained lens transparency by preventing fibrotic plaques formation. Conclusions We first identified that LSS protected LECs from EMT and played an antifibrotic role to maintain lens transparency. Additionally, lanosterol and sterol biosynthesis regulation might be promising strategies for preventing and treating fibrotic cataracts.
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Affiliation(s)
- Pengjuan Ma
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Jingqi Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Baoxin Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Mi Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Lang Xiong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Jieping Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Shan Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
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10
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Takashima M, Taniguchi K, Nagaya M, Yamamura S, Takamura Y, Inatani M, Oki M. Gene profiles and mutations in the development of cataracts in the ICR rat model of hereditary cataracts. Sci Rep 2023; 13:18161. [PMID: 37875594 PMCID: PMC10598066 DOI: 10.1038/s41598-023-45088-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/16/2023] [Indexed: 10/26/2023] Open
Abstract
Cataracts are opacifications of the lens that cause loss of visual acuity and ultimately of eyesight. Age-related cataract develops in most elderly people, but the mechanisms of cataract onset are incompletely understood. The Ihara Cataract Rat (ICR) is an animal model of hereditary cataracts showing cortical opacity that commonly develops prematurely. We identified putative mechanisms of cataract onset in the ICR rat model by measuring gene expression changes before and after cortical cataract development and conducting point mutation analysis. Genes differentially expressed between 4-week-old animals without cortical cataracts and 8-10-week-old animals with cortical cataracts were selected from microarray analysis. Three connections were identified by STRING analysis: (i) Epithelial-Mesenchymal Transition (EMT), including Col1a2, and Pik3r1. (ii) Lens homeostasis, including Aqp5, and Cpm. (iii) Lipid metabolism, including Scd1, Srebf1, and Pnpla3. Subsequently, mutation points were selected by comparing ICR rats with 12 different rats that do not develop cataracts. The apolipoprotein Apoc3 was mutated in ICR rats. Analyses of gene expression changes and point and mutations suggested that abnormalities in EMT or lipid metabolism could contribute to cataract development in ICR rats.
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Affiliation(s)
- Masaru Takashima
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Kei Taniguchi
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Masaya Nagaya
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Shunki Yamamura
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Yoshihiro Takamura
- Department of Ophthalmology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masaru Inatani
- Department of Ophthalmology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masaya Oki
- Department of Industrial Creation Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan.
- Life Science Innovation Center, University of Fukui, Fukui, Japan.
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11
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Pikuleva IA. Challenges and Opportunities in P450 Research on the Eye. Drug Metab Dispos 2023; 51:1295-1307. [PMID: 36914277 PMCID: PMC10506698 DOI: 10.1124/dmd.122.001072] [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: 08/14/2022] [Revised: 02/14/2023] [Accepted: 03/06/2023] [Indexed: 03/15/2023] Open
Abstract
Of the 57 cytochrome P450 enzymes found in humans, at least 30 have ocular tissues as an expression site. Yet knowledge of the roles of these P450s in the eye is limited, in part because only very few P450 laboratories expanded their research interests to studies of the eye. Hence the goal of this review is to bring attention of the P450 community to the eye and encourage more ocular studies. This review is also intended to be educational for eye researchers and encourage their collaborations with P450 experts. The review starts with a description of the eye, a fascinating sensory organ, and is followed by sections on ocular P450 localizations, specifics of drug delivery to the eye, and individual P450s, which are grouped and presented based on their substrate preferences. In sections describing individual P450s, available eye-relevant information is summarized and concluded by the suggestions on the opportunities in ocular studies of the discussed enzymes. Potential challenges are addressed as well. The conclusion section outlines several practical suggestions on how to initiate eye-related research. SIGNIFICANCE STATEMENT: This review focuses on the cytochrome P450 enzymes in the eye to encourage their ocular investigations and collaborations between P450 and eye researchers.
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Affiliation(s)
- Irina A Pikuleva
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio
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12
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Hazen P, Trossi-Torres G, Khadka NK, Timsina R, Mainali L. Binding of β L-Crystallin with Models of Animal and Human Eye Lens-Lipid Membrane. Int J Mol Sci 2023; 24:13600. [PMID: 37686406 PMCID: PMC10487507 DOI: 10.3390/ijms241713600] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
Several discoveries show that with age and cataract formation, β-crystallin binds with the lens membrane or associates with other lens proteins, which bind with the fiber cell plasma membrane, accompanied by light scattering and cataract formation. However, how lipids (phospholipids and sphingolipids) and cholesterol (Chol) influence β-crystallin binding to the membrane is unclear. This research aims to elucidate the role of lipids and Chol in the binding of β-crystallin to the membrane and the membrane's physical properties (mobility, order, and hydrophobicity) with β-crystallin binding. We used electron paramagnetic resonance (EPR) spin-labeling methods to investigate the binding of βL-crystallin with a model of porcine lens-lipid (MPLL), model of mouse lens-lipid (MMLL), and model of human lens-lipid (MHLL) membrane with and without Chol. Our results show that βL-crystallin binds with all of the investigated membranes in a saturation manner, and the maximum parentage of the membrane surface occupied (MMSO) by βL-crystallin and the binding affinity (Ka) of βL-crystallin to the membranes followed trends: MMSO (MPLL) > MMSO (MMLL) > MMSO (MHLL) and Ka (MHLL) > Ka (MMLL) ≈ Ka (MPLL), respectively, in which the presence of Chol reduces the MMSO and Ka for all membranes. The mobility near the headgroup regions of the membranes decreases with an increase in the binding of βL-crystallin; however, the decrease is more pronounced in the MPLL and MMLL membranes than the MHLL membrane. In the MPLL and MMLL membranes, the membranes become slightly ordered near the headgroup with an increase in βL-crystallin binding compared to the MHLL membrane. The hydrophobicity near the headgroup region of the membrane increases with βL-crystallin binding; however, the increase is more pronounced in the MPLL and MMLL membranes than the MHLL membrane, indicating that βL-crystallin binding creates a hydrophobic barrier for the passage of polar molecules, which supports the barrier hypothesis in cataract formation. However, in the presence of Chol, there is no significant increase in hydrophobicity with βL-crystallin binding, suggesting that Chol prevents the formation of a hydrophobic barrier, possibly protecting against cataract formation.
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Affiliation(s)
- Preston Hazen
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.)
| | - Geraline Trossi-Torres
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.)
- Department of Physics, Boise State University, Boise, ID 83725, USA; (N.K.K.); (R.T.)
| | - Nawal K. Khadka
- Department of Physics, Boise State University, Boise, ID 83725, USA; (N.K.K.); (R.T.)
| | - Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA; (N.K.K.); (R.T.)
| | - Laxman Mainali
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA; (P.H.); (G.T.-T.)
- Department of Physics, Boise State University, Boise, ID 83725, USA; (N.K.K.); (R.T.)
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13
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Park J, MacGavin S, Niederbrach L, Mchaourab HS. Interplay between Nrf2 and αB-crystallin in the lens and heart of zebrafish under proteostatic stress. Front Mol Biosci 2023; 10:1185704. [PMID: 37577747 PMCID: PMC10422029 DOI: 10.3389/fmolb.2023.1185704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 06/27/2023] [Indexed: 08/15/2023] Open
Abstract
A coordinated oxidative stress response, partly triggered by the transcription factor Nrf2, protects cells from the continual production of reactive oxygen species. Left unbuffered, reactive oxygen species can lead to protein aggregation that has been implicated in a spectrum of diseases such as cataract of the ocular lens and myopathy of the heart. While proteostasis is maintained by diverse families of heat shock proteins, the interplay between the oxidative and proteostatic stress responses in the lens and heart has not been investigated. Capitalizing on multiple zebrafish lines that have compromised function of Nrf2 and/or the two zebrafish small heat shock proteins αBa- and αBb-crystallin, we uncovered a transcriptional relationship that leads to a substantial increase in αBb-crystallin transcripts in the heart in response to compromised function of Nrf2. In the lens, the concomitant loss of function of Nrf2 and αBa-crystallin leads to upregulation of the cholesterol biosynthesis pathway, thus mitigating the phenotypic consequences of the αBa-crystallin knockout. By contrast, abrogation of Nrf2 function accentuates the penetrance of a heart edema phenotype characteristic of embryos of αB-crystallin knockout lines. Multiple molecular pathways, such as genes involved in extracellular interactions and implicated in cardiomyopathy, are revealed from transcriptome profiling, thus identifying novel targets for further investigation. Together, our transcriptome/phenotypic analysis establishes an intersection between oxidative stress and chaperone responses in the lens and heart.
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Affiliation(s)
| | | | | | - Hassane S. Mchaourab
- From the Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States
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14
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Mardešić I, Boban Z, Subczynski WK, Raguz M. Membrane Models and Experiments Suitable for Studies of the Cholesterol Bilayer Domains. MEMBRANES 2023; 13:320. [PMID: 36984707 PMCID: PMC10057498 DOI: 10.3390/membranes13030320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/06/2023] [Accepted: 03/08/2023] [Indexed: 06/18/2023]
Abstract
Cholesterol (Chol) is an essential component of animal cell membranes and is most abundant in plasma membranes (PMs) where its concentration typically ranges from 10 to 30 mol%. However, in red blood cells and Schwann cells, PMs Chol content is as high as 50 mol%, and in the PMs of the eye lens fiber cells, it can reach up to 66 mol%. Being amphiphilic, Chol molecules are easily incorporated into the lipid bilayer where they affect the membrane lateral organization and transmembrane physical properties. In the aqueous phase, Chol cannot form free bilayers by itself. However, pure Chol bilayer domains (CBDs) can form in lipid bilayer membranes with the Chol content exceeding 50 mol%. The range of Chol concentrations surpassing 50 mol% is less frequent in biological membranes and is consequently less investigated. Nevertheless, it is significant for the normal functioning of the eye lens and understanding how Chol plaques form in atherosclerosis. The most commonly used membrane models are unilamellar and multilamellar vesicles (MLVs) and supported lipid bilayers (SLBs). CBDs have been observed directly using confocal microscopy, X-ray reflectometry and saturation recovery electron paramagnetic resonance (SR EPR). Indirect evidence of CBDs has also been reported by using atomic force microscopy (AFM) and fluorescence recovery after photobleaching (FRAP) experiments. The overall goal of this review is to demonstrate the advantages and limitations of the various membrane models and experimental techniques suitable for the detection and investigation of the lateral organization, function and physical properties of CBDs.
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Affiliation(s)
- Ivan Mardešić
- Department of Medical Physics and Biophysics, University of Split School of Medicine, 21000 Split, Croatia; (I.M.); (Z.B.)
- Faculty of Science, University of Split, Doctoral Study of Biophysics, 21000 Split, Croatia
| | - Zvonimir Boban
- Department of Medical Physics and Biophysics, University of Split School of Medicine, 21000 Split, Croatia; (I.M.); (Z.B.)
- Faculty of Science, University of Split, Doctoral Study of Biophysics, 21000 Split, Croatia
| | | | - Marija Raguz
- Department of Medical Physics and Biophysics, University of Split School of Medicine, 21000 Split, Croatia; (I.M.); (Z.B.)
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15
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Liu Z, Huang S, Zheng Y, Zhou T, Hu L, Xiong L, Li DWC, Liu Y. The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens. Prog Retin Eye Res 2023; 92:101112. [PMID: 36055924 DOI: 10.1016/j.preteyeres.2022.101112] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/28/2022] [Accepted: 08/02/2022] [Indexed: 02/01/2023]
Abstract
The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.
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Affiliation(s)
- Zhenzhen Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Shan Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yingfeng Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Tian Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Leyi Hu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Lang Xiong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - David Wan-Cheng Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China; Research Unit of Ocular Development and Regeneration, Chinese Academy of Medical Sciences, Beijing, 100085, China.
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16
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Timsina R, Wellisch S, Haemmerle D, Mainali L. Binding of Alpha-Crystallin to Cortical and Nuclear Lens Lipid Membranes Derived from a Single Lens. Int J Mol Sci 2022; 23:ijms231911295. [PMID: 36232595 PMCID: PMC9570235 DOI: 10.3390/ijms231911295] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/17/2022] [Accepted: 09/22/2022] [Indexed: 11/16/2022] Open
Abstract
Several studies reported that α-crystallin concentrations in the eye lens cytoplasm decrease with a corresponding increase in membrane-bound α-crystallin with age and cataracts. The influence of the lipid and cholesterol composition difference between cortical membrane (CM) and nuclear membrane (NM) on α-crystallin binding to membranes is still unclear. This study uses the electron paramagnetic resonance (EPR) spin-labeling method to investigate the α-crystallin binding to bovine CM and NM derived from the total lipids extracted from a single lens. Compared to CMs, NMs have a higher percentage of membrane surface occupied by α-crystallin and binding affinity, correlating with less mobility and more order below and on the surface of NMs. α-Crystallin binding to CM and NM decreases mobility with no significant change in order and hydrophobicity below and on the surface of membranes. Our results suggest that α-crystallin mainly binds on the surface of bovine CM and NM and such surface binding of α-crystallin to membranes in clear and young lenses may play a beneficial role in membrane stability. However, with decreased cholesterol content within the CM, which mimics the decreased cholesterol content in the cataractous lens membrane, α-crystallin binding increases the hydrophobicity below the membrane surface, indicating that α-crystallin binding forms a hydrophobic barrier for the passage of polar molecules, supporting the barrier hypothesis in developing cataracts.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | | | - Dieter Haemmerle
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA
- Correspondence: ; Tel.: +1-(208)-426-4003
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17
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Carlson J, McBride K, O’Connor M. Drugs associated with cataract formation represent an unmet need in cataract research. Front Med (Lausanne) 2022; 9:947659. [PMID: 36045926 PMCID: PMC9420850 DOI: 10.3389/fmed.2022.947659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/13/2022] [Indexed: 11/13/2022] Open
Abstract
Decreased light transmittance through the ocular lens, termed cataract, is a leading cause of low vision and blindness worldwide. Cataract causes significantly decreased quality of life, particularly in the elderly. Environmental risk factors, including aging, UV exposure, diabetes, smoking and some prescription drugs, are all contributors to cataract formation. In particular, drug-induced cataract represents a poorly-addressed source of cataract. To better understand the potential impact of prescription drugs on cataract, we analyzed publicly-available drug prescriptions data from the Australian Pharmaceutical Benefits Scheme. The data was analyzed for the 5-year period from July 2014 to June 2019. Analyses included the number of prescriptions for each drug, as well as the associated government and total prescription costs. The drugs chosen for analysis belonged to any of four broad categories—those with known, probable, possible or uncertain association with cataract in patients. The analyses revealed high prescription rates and costs for drugs in the Known category (e.g., steroids) and Possible category (e.g., psychotropic drugs). Collectively, these data provide valuable insights into specific prescription drugs that likely contribute to the increasing annual burden of new cataract cases. These data highlight the need—as well as new, stem cell-based opportunities—to elucidate molecular mechanisms of drug-induced cataract formation.
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Affiliation(s)
- Jack Carlson
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Kate McBride
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- Translational Health Research Institute, Western Sydney University, Campbelltown, NSW, Australia
| | - Michael O’Connor
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- Translational Health Research Institute, Western Sydney University, Campbelltown, NSW, Australia
- *Correspondence: Michael O’Connor,
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18
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Khadka NK, Mortimer MF, Marosvari M, Timsina R, Mainali L. Membrane elasticity modulated by cholesterol in model of porcine eye lens-lipid membrane. Exp Eye Res 2022; 220:109131. [PMID: 35636489 PMCID: PMC10131281 DOI: 10.1016/j.exer.2022.109131] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 05/08/2022] [Accepted: 05/22/2022] [Indexed: 11/29/2022]
Abstract
Experimental evidence shows that the eye lens loses its elasticity dramatically with age. It has also been reported that the cholesterol (Chol) content in the eye lens fiber cell plasma membrane increases significantly with age. High Chol content leads to the formation of cholesterol bilayer domains (CBDs) in the lens membrane. The role of high Chol associated with lens elasticity is unclear. The purpose of this research is to investigate the membrane elasticity of the model of porcine lens-lipid (MPLL) membrane with increasing Chol content to elucidate the role of high Chol in lens membrane elasticity. In this study, we used atomic force microscopy (AFM) to study the mechanical properties (breakthrough force and area compressibility modulus (KA)) of the MPLL membrane with increasing Chol content where KA is the measure of membrane elasticity. We varied Chol concentration in Chol/MPLL membrane from 0 to ∼71 mol%. Supported Chol/MPLL membranes were prepared by fusion of small unilamellar vesicles (SUVs) on top of a flat mica surface. SUVs of the Chol/MPLL lipid mixture were prepared with the rapid solvent exchange method followed by probe-tip sonication. For the Chol/MPLL mixing ratio of 0, AFM image showed the formation of two distinct phases of the membrane, i.e., liquid-disordered phase (ld) and solid-ordered phase (so) membrane. However, with Chol/MPLL mixing ratio of 0.5 and above, only liquid-ordered phase (lo) membrane was formed. Also, two distinct breakthrough forces corresponding to ld and so were observed for Chol/MPLL mixing ratio of 0, whereas only one breakthrough force was observed for membranes with Chol/MPLL mixing ratio of 0.5 and above. No significant difference in the membrane surface roughness was measured with increasing Chol content for these membranes; however, breakthrough force and KA for lo membrane increased when Chol/MPLL mixing ratio was increased from 0.5 to 1. Interestingly above the Chol/MPLL mixing ratio of 1, both breakthrough force and KA decreased, indicating the formation of CBDs. Furthermore, these results showed that membrane elasticity increases at high Chol content, suggesting that high Chol content in lens membrane might be responsible for maintaining lens membrane elasticity.
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Affiliation(s)
- Nawal K Khadka
- Department of Physics, Boise State University, Boise, ID, USA
| | | | - Mason Marosvari
- Department of Physics, Boise State University, Boise, ID, USA
| | - Raju Timsina
- Department of Physics, Boise State University, Boise, ID, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID, USA; Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, USA.
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19
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Amino acid regulated co-assembly for formation of one-dimensional ordered monocrystal by hydrogen bonding interactions. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.128169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Timsina R, Trossi-Torres G, Thieme J, O'Dell M, Khadka NK, Mainali L. Alpha-Crystallin Association with the Model of Human and Animal Eye Lens-Lipid Membranes is Modulated by Surface Hydrophobicity of Membranes. Curr Eye Res 2022; 47:843-853. [PMID: 35179407 DOI: 10.1080/02713683.2022.2040539] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE This research aims to probe the interaction of α-crystallin with a model of human, porcine, and mouse lens-lipid membranes. METHODS Cholesterol/model of human lens-lipid (Chol/MHLL), cholesterol/model of porcine lens-lipid (Chol/MPLL), and cholesterol/model of mouse lens-lipid (Chol/MMLL) membranes with 0 to 60 mol% Chol were prepared using the rapid solvent exchange method and probe-tip sonication. The hydrophobicity near the surface of model lens-lipid membranes and α-crystallin association with these membranes were investigated using the electron paramagnetic resonance spin-labeling approach. RESULTS With increased Chol content, the hydrophobicity near the surface of Chol/MHLL, Chol/MPLL, and Chol/MMLL membranes, the maximum percentage of membrane surface occupied (MMSO) by α-crystallin, and the association constant (Ka) decreased, showing that surface hydrophobicity of model lens-lipid membranes modulated the α-crystallin association with these membranes. The different MMSO and Ka for different model lens-lipid membranes with different rates of decrease of MMSO and Ka with increased Chol content and decreased hydrophobicity near the surface of these membranes suggested that the lipid composition also modulates α-crystallin association with membranes. Despite different lipid compositions, complete inhibition of α-crystallin association with model lens-lipid membranes was observed at saturating Chol content forming cholesterol bilayer domains (CBDs) with the lowest hydrophobicity near the surface of these membranes. The decreased mobility parameter with increased α-crystallin concentration suggested that membranes near the surface became less mobile due to α-crystallin association. The decreased mobility parameter and increased maximum splitting with increased Chol content suggested that membranes became less mobile and more ordered near the surface with increased Chol content. CONCLUSIONS This study suggested that the interaction of α-crystallin with model lens-lipid membranes is hydrophobic. Furthermore, our data indicated that Chol and CBDs reduce α-crystallin association with lens membrane, likely increase α-crystallin concentration in lens cytoplasm, and possibly favor the chaperone-like activity of α-crystallin maintaining lens cytoplasm homeostasis.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | | | - Jackson Thieme
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Matthew O'Dell
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Nawal K Khadka
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID 83725, USA.,Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
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21
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Subczynski WK, Widomska J, Stein N, Swartz HM. Factors determining barrier properties to oxygen transport across model and cell plasma membranes based on EPR spin-label oximetry. APPLIED MAGNETIC RESONANCE 2021; 52:1237-1260. [PMID: 36267674 PMCID: PMC9581439 DOI: 10.1007/s00723-021-01412-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 07/23/2021] [Accepted: 08/04/2021] [Indexed: 06/01/2023]
Abstract
This review is motivated by the exciting new area of radiation therapy using a phenomenon termed FLASH in which oxygen is thought to have a central role. Well-established principles of radiation biology and physics suggest that if oxygen has a strong role, it should be the level at the DNA. The key aspect discussed is the rate of oxygen diffusion. If oxygen freely diffuses into cells and rapidly equilibrates, then measurements in the extracellular compartment would enable FLASH to be investigated using existing methodologies that can readily measure oxygen in the extracellular compartment. EPR spin-label oximetry allows evaluation of the oxygen permeability coefficient across lipid bilayer membranes. It is established that simple fluid phase lipid bilayers are not barriers to oxygen transport. However, further investigations indicate that many physical and chemical (compositional) factor can significantly decrease this permeation. In biological cell plasma membranes, the lipid bilayer forms the matrix in which integral membrane proteins are immersed, changing organization and properties of the lipid matrix. To evaluate oxygen permeability coefficients across these complex membranes, oxygen permeation across all membrane domains and components must be considered. In this review, we consider many of the factors that affect (decrease) oxygen permeation across cell plasma membranes. Finally, we address the question, can the plasma membrane of the cell form a barrier to the free diffusion of oxygen into the cell interior? If there is a barrier then this must be considered in the investigations of the role of oxygen in FLASH.
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Affiliation(s)
- Witold K. Subczynski
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Justyna Widomska
- Department of Biophysics, Medical University of Lublin, Jaczewskiego 4, Lublin, Poland
| | - Natalia Stein
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Harold M. Swartz
- Department of Radiology, The Geisel School of Medicine at Dartmouth, Lebanon, NH 03766, USA
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22
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Timsina R, Mainali L. Association of Alpha-Crystallin with Fiber Cell Plasma Membrane of the Eye Lens Accompanied by Light Scattering and Cataract Formation. MEMBRANES 2021; 11:447. [PMID: 34203836 PMCID: PMC8232717 DOI: 10.3390/membranes11060447] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 02/04/2023]
Abstract
α-crystallin is a major protein found in the mammalian eye lens that works as a molecular chaperone by preventing the aggregation of proteins and providing tolerance to stress in the eye lens. These functions of α-crystallin are significant for maintaining lens transparency. However, with age and cataract formation, the concentration of α-crystallin in the eye lens cytoplasm decreases with a corresponding increase in the membrane-bound α-crystallin, accompanied by increased light scattering. The purpose of this review is to summarize previous and recent findings of the role of the: (1) lens membrane components, i.e., the major phospholipids (PLs) and sphingolipids, cholesterol (Chol), cholesterol bilayer domains (CBDs), and the integral membrane proteins aquaporin-0 (AQP0; formally MIP26) and connexins, and (2) α-crystallin mutations and post-translational modifications (PTMs) in the association of α-crystallin to the eye lens's fiber cell plasma membrane, providing thorough insights into a molecular basis of such an association. Furthermore, this review highlights the current knowledge and need for further studies to understand the fundamental molecular processes involved in the association of α-crystallin to the lens membrane, potentially leading to new avenues for preventing cataract formation and progression.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA;
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID 83725, USA;
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
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23
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Faranda AP, Shihan MH, Wang Y, Duncan MK. The aging mouse lens transcriptome. Exp Eye Res 2021; 209:108663. [PMID: 34119483 DOI: 10.1016/j.exer.2021.108663] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/04/2021] [Accepted: 06/01/2021] [Indexed: 02/06/2023]
Abstract
Age is a major risk factor for cataract (ARC). However, the influence of aging on the lens transcriptome is under studied. Lens epithelial (LEC) and fiber cells (LFC) were isolated from young (3 month old) and aged (24 month old) C57BL/6J mice, and the transcriptome elucidated via RNAseq. EdgeR estimated differential gene expression in pairwise contrasts, and Advaita's Ipathway guide and custom R scripts were used to evaluate the potential biological significance of differentially expressed genes (DEGs). This analysis revealed age-dependent decreases in lens differentiation marker expression in both LECs and LFCs, with gamma crystallin transcripts downregulating nearly 50 fold in aged LFCs. The expression of the transcription factors Hsf4 and Maf, which are known to activate lens fiber cell preferred genes, are downregulated, while FoxE3, which represses gamma crystallin expression, is upregulated in aged fibers. Aged LECs upregulate genes controlling the immune response, complement pathways, and cellular stress responses, including glutathione peroxidase 3 (Gpx3). Aged LFCs exhibit broad changes in the expression of genes regulating cell communication, and upregulate genes involved in antigen processing/presentation and cholesterol metabolism, while changes in the expression of mitochondrial respiratory chain genes are consistent with mitochondrial stress, including upregulation of NDufa4l2, which encodes an alternate electron transport chain protein. However, age did not profoundly affect the response of LECs to injury as both young and aged LECs upregulate inflammatory gene signatures at 24 h post injury to similar extents. These RNAseq profiles provide a rich data set that can be mined to understand the genetic regulation of lens aging and how this impinges on the pathophysiology of age related cataract.
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Affiliation(s)
- Adam P Faranda
- Department of Biological Sciences University of Delaware Newark, DE, 19716, USA
| | - Mahbubul H Shihan
- Department of Biological Sciences University of Delaware Newark, DE, 19716, USA
| | - Yan Wang
- Department of Biological Sciences University of Delaware Newark, DE, 19716, USA
| | - Melinda K Duncan
- Department of Biological Sciences University of Delaware Newark, DE, 19716, USA.
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24
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Timsina R, Trossi-Torres G, O'Dell M, Khadka NK, Mainali L. Cholesterol and cholesterol bilayer domains inhibit binding of alpha-crystallin to the membranes made of the major phospholipids of eye lens fiber cell plasma membranes. Exp Eye Res 2021; 206:108544. [PMID: 33744256 PMCID: PMC8087645 DOI: 10.1016/j.exer.2021.108544] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/05/2021] [Accepted: 03/10/2021] [Indexed: 11/16/2022]
Abstract
The concentration of α-crystallin decreases in the eye lens cytoplasm, with a corresponding increase in membrane-bound α-crystallin during cataract formation. The eye lens's fiber cell plasma membrane consists of extremely high cholesterol (Chol) content, forming cholesterol bilayer domains (CBDs) within the membrane. The role of high Chol content in the lens membrane is unclear. Here, we applied the continuous-wave electron paramagnetic resonance spin-labeling method to probe the role of Chol and CBDs on α-crystallin binding to membranes made of four major phospholipids (PLs) of the eye lens, i.e., phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylserine (PS), and phosphatidylethanolamine (PE). Small unilamellar vesicles (SUVs) of PC, SM*, and PS with 0, 23, 33, 50, and 60 mol% Chol and PE* with 0, 9, and 33 mol% Chol were prepared using the rapid solvent exchange method followed by probe-tip sonication. The 1 mol% CSL spin-labels used during SUVs preparation distribute uniformly within the Chol/PL membrane, enabling the investigation of Chol and CBDs' role on α-crystallin binding to the membrane. For PC, SM*, and PS membranes, the binding affinity (Ka) and the maximum percentage of membrane surface occupied (MMSO) by α-crystallin decreased with an increase in Chol concentration. The Ka and MMSO became zero at 50 mol% Chol for PC and 60 mol% Chol for SM* membranes, representing that complete inhibition of α-crystallin binding was possible before the formation of CBDs within the PC membrane but only after the formation of CBDs within the SM* membrane. The Ka and MMSO did not reach zero even at 60 mol% Chol in the PS membrane, representing CBDs at this Chol concentration were not sufficient for complete inhibition of α-crystallin binding to the PS membrane. Both the Ka and MMSO were zero at 0, 9, and 33 mol% Chol in the PE* membrane, representing no binding of α-crystallin to the PE* membrane with and without Chol. The mobility parameter profiles decreased with an increase in α-crystallin binding to the membranes; however, the decrease was more pronounced for the membrane with lower Chol concentration. These results imply that the membranes become more immobilized near the headgroup regions with an increase in α-crystallin binding; however, the Chol antagonizes the capacity of α-crystallin to decrease the mobility near the headgroup regions of the membranes. The maximum splitting profiles remained the same with an increase in α-crystallin concentration, but there was an increase in the maximum splitting with an increase in the Chol concentration in the membranes. It implies that membrane order near the headgroup regions does not change with an increase in α-crystallin concentration but increases with an increase in Chol concentration in the membrane. Based on our data, we hypothesize that the Chol and CBDs decrease hydrophobicity (increase polarity) near the membrane surface, inhibiting the hydrophobic binding of α-crystallin to the membranes. Thus, our data suggest that Chol and CBDs play a positive physiological role by preventing α-crystallin binding to lens membranes and possibly protecting against cataract formation and progression.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID, 83725, USA
| | | | - Matthew O'Dell
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, 83725, USA
| | - Nawal K Khadka
- Department of Physics, Boise State University, Boise, ID, 83725, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID, 83725, USA; Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, 83725, USA.
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25
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Khadka NK, Timsina R, Rowe E, O'Dell M, Mainali L. Mechanical properties of the high cholesterol-containing membrane: An AFM study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183625. [PMID: 33891910 DOI: 10.1016/j.bbamem.2021.183625] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 04/02/2021] [Accepted: 04/12/2021] [Indexed: 12/11/2022]
Abstract
Cholesterol (Chol) content in most cellular membranes does not exceed 50 mol%, only in the eye lens's fiber cell plasma membrane, its content surpasses 50 mol%. At this high concentration, Chol induces the formation of pure cholesterol bilayer domains (CBDs), which coexist with the surrounding phospholipid-cholesterol domain (PCD). Here, we applied atomic force microscopy to study the mechanical properties of Chol/phosphatidylcholine membranes where the Chol content was increased from 0 to 75 mol%, relevant to eye lens membranes. The surface roughness of the membrane decreases with an increase of Chol content until it reaches 60 mol%, and roughness increases with a further increment in Chol content. We propose that the increased roughness at higher Chol content results from the formation of CBDs. Force spectroscopy on the membrane with Chol content of 50 mol% or lesser exhibited single breakthrough events, whereas two distinct puncture events were observed for membranes with the Chol content greater than 50 mol%. We propose that the first puncture force corresponds to the membranes containing coexisting PCD and CBDs. In contrast, the second puncture force corresponds to the "CBD water pocket" formed due to coexisting CBDs and PCD. Membrane area compressibility modulus (KA) increases with an increase in Chol content until it reaches 60 mol%, and with further increment in Chol content, CBDs are formed, and KA starts to decrease. Our results report the increase in membrane roughness and decrease KA at very high Chol content (>60 mol%) relevant to the eye lens membrane.
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Affiliation(s)
- Nawal K Khadka
- Department of Physics, Boise State University, Boise, ID, USA
| | - Raju Timsina
- Department of Physics, Boise State University, Boise, ID, USA
| | - Erica Rowe
- Department of Biology, Boise State University, Boise, ID, USA
| | - Matthew O'Dell
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID, USA; Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, USA.
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26
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Ma GJ, Zhdanov VP, Park S, Sut TN, Cho NJ. Mechanistic Aspects of the Evolution of 3D Cholesterol Crystallites in a Supported Lipid Membrane via a Quartz Crystal Microbalance with Dissipation Monitoring. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:4562-4570. [PMID: 33834785 DOI: 10.1021/acs.langmuir.1c00174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The irreversible formation of cholesterol monohydrate crystals within biological membranes is the leading cause of various diseases, including atherosclerosis. Understanding the process of cholesterol crystallization is fundamentally important and could also lead to the development of improved therapeutic strategies. This has driven several studies investigating the effect of the environmental parameters on the induction of cholesterol crystallite growth and the structure of the cholesterol crystallites, while the kinetics and mechanistic aspects of the crystallite formation process within lipid membranes remain poorly understood. Herein, we fabricated cholesterol crystallites within a supported lipid bilayer (SLB) by adsorbing a cholesterol-rich bicellar mixture onto a glass and silica surface and investigated the real-time kinetics of cholesterol crystallite nucleation and growth using epifluorescence microscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring. Microscopic imaging showed the evolution of the morphology of cholesterol crystallites from nanorod- and plate-shaped habits during the initial stage to mostly large, micron-sized three-dimensional (3D) plate-shaped crystallites in the end, which was likened to Ostwald ripening. QCM-D kinetics revealed unique signal responses during the later stage of the growth process, characterized by simultaneous positive frequency shifts, nonmonotonous energy dissipation shifts, and significant overtone dependence. Based on the optically observed changes in crystallite morphology, we discussed the physical background of these unique QCM-D signal responses and the mechanistic aspects of Ostwald ripening in this system. Together, our findings revealed mechanistic details of the cholesterol crystallite growth kinetics, which may be useful in biointerfacial sensing and bioanalytical applications.
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Affiliation(s)
- Gamaliel Junren Ma
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Vladimir P Zhdanov
- Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Soohyun Park
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Tun Naw Sut
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
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27
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Raguz M, Kumar SN, Zareba M, Ilic N, Mainali L, Subczynski WK. Confocal Microscopy Confirmed that in Phosphatidylcholine Giant Unilamellar Vesicles with very High Cholesterol Content Pure Cholesterol Bilayer Domains Form. Cell Biochem Biophys 2019; 77:309-317. [PMID: 31625023 DOI: 10.1007/s12013-019-00889-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 09/28/2019] [Indexed: 12/14/2022]
Abstract
The cholesterol (Chol) content in the fiber cell plasma membranes of the eye lens is extremely high, exceeding the solubility threshold in the lenses of old humans. This high Chol content forms pure Chol bilayer domains (CBDs) and Chol crystals in model membranes and membranes formed from the total lipid extracts from human lenses. CBDs have been detected using electron paramagnetic resonance (EPR) spin-labeling approaches. Here, we confirm the presence of CBDs in giant unilamellar vesicles prepared using the electroformation method from Chol/1-palmitoyl-2-oleoylphosphocholine and Chol/distearoylphosphatidylcholine mixtures. Confocal microscopy experiments using phospholipid (PL) analog (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine-5,5'-disulfonic acid) and cholesterol analog fluorescent probes (23-(dipyrrometheneboron difluoride)-24-norcholesterol) were performed, allowing us to make three major conclusions: (1) In all membranes with a Chol/PL mixing ratio (expressed as a molar ratio) >2, pure CBDs were formed within the bulk PL bilayer saturated with Chol. (2) CBDs were present as the pure Chol bilayer and not as separate patches of Chol monolayers in each leaflet of the PL bilayer. (3) CBDs, presented as single large domains, were always located at the top of giant unilamellar vesicles, independent of the change in sample orientation (right-side-up/upside-down). Results obtained with confocal microscopy and fluorescent Chol and PL analogs, combined with those obtained using EPR and spin-labeled Chol and PL analogs, contribute to the understanding of the organization of lipids in the fiber cell plasma membranes of the human eye lens.
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Affiliation(s)
- Marija Raguz
- Department of Medical Physics and Biophysics, School of Medicine, University of Split, Split, Croatia. .,Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.
| | - Suresh N Kumar
- Department of Pathology, CRI Imaging Core, Translational and Biomedical Research Center, Medical College of Wisconsin, Wauwatosa, WI, USA
| | - Mariusz Zareba
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Ophthalmology, Medical College of Wisconsin Eye Institute, Milwaukee, WI, USA
| | - Nada Ilic
- Department of Physics, Faculty of Science, University of Split, Split, Croatia
| | - Laxman Mainali
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Physics, Boise State University, 1910 University Drive, Boise, Idaho, 83725, USA
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28
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New Insights into Cholesterol Functions: A Friend or an Enemy? Nutrients 2019; 11:nu11071645. [PMID: 31323871 PMCID: PMC6682969 DOI: 10.3390/nu11071645] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 02/06/2023] Open
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