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Vinnett A, Kandukuri J, Le C, Cho KA, Sinha A, Asanad S, Thompson G, Chen V, Rege A, Saeedi OJ. Dynamic Alterations in Blood Flow in Glaucoma Measured with Laser Speckle Contrast Imaging. Ophthalmol Glaucoma 2022; 5:250-261. [PMID: 34673279 PMCID: PMC9013729 DOI: 10.1016/j.ogla.2021.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/30/2021] [Accepted: 10/08/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE To assess the repeatability of blood flow velocity index (BFVi) metrics obtained with a recently Food and Drug Administration-cleared laser speckle contrast imaging device, the XyCAM RI (Vasoptic Medical, Inc), and to characterize differences in these metrics among control, glaucoma suspect, and glaucoma participants. DESIGN Prospective, observational study. PARTICIPANTS Forty-six participants: 20 control, 16 glaucoma suspect, and 10 glaucoma participants, 1 eye per participant. METHODS Key dynamic BFVi metrics-mean, peak, dip, volumetric rise index (VRI), volumetric fall index (VFI), time to rise (TtR), time to fall (TtF), blow-out time (BOT), skew, and acceleration time index-were measured in the optic disc, optic disc vessels, optic disc perfusion region, and macula in 4 imaging sessions on the same day. Intrasession and intersession variability were calculated using the coefficient of variation (CV) for each metric in each region of interest (ROI). Values for each dynamic BFVi variable were compared between glaucoma, glaucoma suspect, and control participants using bivariate and multivariate analysis. Pearson correlation coefficients were used to correlate each variable in each ROI with age, intraocular pressure, cup-to-disc ratio (CDR), mean deviation, pattern standard deviation, retinal nerve fiber layer thickness, and minimum rim width. MAIN OUTCOME MEASURES Coefficient of variation for the intrasession and intersession variability for each dynamic BFVi metric in each ROI and differences in each metric in each ROI between each diagnostic group. RESULTS Intersession CV for mean, peak, dip, VRI, VFI, TtR, and TtF ranged from 3.2 ± 2.5% to 11.0 ± 3.8%. Age, CDR, OCT metrics, and visual field metrics showed significant correlations with dynamic BFVi variables. Peak, mean, dip, VRI, and VFI were significantly lower in patients with glaucoma than in control participants in all ROIs except the fovea. These metrics also were significantly lower in glaucoma patients than glaucoma suspect patients in the disc vessels. CONCLUSIONS Dynamic blood flow metrics measured with the XyCAM RI are reliable, are associated with structural and functional glaucoma metrics, and are significantly different among glaucoma, glaucoma suspect, and control participants. The XyCAM RI may serve as an important tool in glaucoma management in the future.
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Affiliation(s)
- Alfred Vinnett
- Department of Ophthalmology and Visual Sciences, University of Maryland Baltimore, Baltimore, Maryland
| | | | - Christopher Le
- Department of Ophthalmology and Visual Sciences, University of Maryland Baltimore, Baltimore, Maryland
| | | | | | - Samuel Asanad
- Department of Ophthalmology and Visual Sciences, University of Maryland Baltimore, Baltimore, Maryland
| | - Ginger Thompson
- Department of Ophthalmology/Hamilton Eye Institute, University of Tennessee Health Sciences Center, Memphis, Tennessee
| | - Victoria Chen
- Department of Ophthalmology and Visual Sciences, University of Maryland Baltimore, Baltimore, Maryland
| | | | - Osamah J Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland Baltimore, Baltimore, Maryland.
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Cho KA, Rege A, Jing Y, Chaurasia A, Guruprasad A, Arthur E, Cabrera DeBuc D. Portable, non-invasive video imaging of retinal blood flow dynamics. Sci Rep 2020; 10:20236. [PMID: 33214571 PMCID: PMC7677377 DOI: 10.1038/s41598-020-76407-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 07/27/2020] [Indexed: 02/04/2023] Open
Abstract
Retinal blood flow (RBF) information has the potential to offer insight into ophthalmic health and disease that is complementary to traditional anatomical biomarkers as well as to retinal perfusion information provided by fluorescence or optical coherence tomography angiography (OCT-A). The present study was performed to test the functional attributes and performance of the XyCAM RI, a non-invasive imager that obtains and assesses RBF information. The XyCAM RI was installed and used in two different settings to obtain video recordings of the blood flow in the optic nerve head region in eyes of healthy subjects. The mean blood flow velocity index (BFVi) in the optic disc and in each of multiple arterial and venous segments was obtained and shown to reveal a temporal waveform with a peak and trough that correlates with a cardiac cycle as revealed by a reference pulse oximeter (correlation between respective peak-to-peak distances was 0.977). The intra-session repeatability of the XyCAM RI was high with a coefficient of variation (CV) of 1.84 ± 1.13% across both sites. Artery-vein comparisons were made by estimating, in a pair of adjacent arterial and venous segments, various temporal waveform metrics such as pulsatility index, percent time in systole and diastole, and change in vascular blood volume over a cardiac cycle. All arterial metrics were shown to have significant differences with venous metrics (p < 0.001). The XyCAM RI, therefore, by obtaining repeatable blood flow measurements with high temporal resolution, permits the differential assessment of arterial and venous blood flow patterns in the retina that may facilitate research into disease pathophysiology and biomarker development for diagnostics.
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Affiliation(s)
| | | | - Yici Jing
- Vasoptic Medical, Inc., Baltimore, MD, USA
| | | | | | - Edmund Arthur
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Delia Cabrera DeBuc
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 N.W. 10th Avenue, Room 509, Miami, FL, 33136, USA.
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Uyanik I, Sefati S, Stamper SA, Cho KA, Ankarali MM, Fortune ES, Cowan NJ. Variability in locomotor dynamics reveals the critical role of feedback in task control. eLife 2020; 9:51219. [PMID: 31971509 PMCID: PMC7041942 DOI: 10.7554/elife.51219] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 01/21/2020] [Indexed: 11/19/2022] Open
Abstract
Animals vary considerably in size, shape, and physiological features across individuals, but yet achieve remarkably similar behavioral performances. We examined how animals compensate for morphophysiological variation by measuring the system dynamics of individual knifefish (Eigenmannia virescens) in a refuge tracking task. Kinematic measurements of Eigenmannia were used to generate individualized estimates of each fish’s locomotor plant and controller, revealing substantial variability between fish. To test the impact of this variability on behavioral performance, these models were used to perform simulated ‘brain transplants’—computationally swapping controllers and plants between individuals. We found that simulated closed-loop performance was robust to mismatch between plant and controller. This suggests that animals rely on feedback rather than precisely tuned neural controllers to compensate for morphophysiological variability. People come in different shapes and sizes, but most will perform similarly well if asked to complete a task requiring fine manual dexterity – such as holding a pen or picking up a single grape. How can different individuals, with different sized hands and muscles, produce such similar movements? One explanation is that an individual’s brain and nervous system become precisely tuned to mechanics of the body’s muscles and skeleton. An alternative explanation is that brain and nervous system use a more “robust” control policy that can compensate for differences in the body by relying on feedback from the senses to guide the movements. To distinguish between these two explanations, Uyanik et al. turned to weakly electric freshwater fish known as glass knifefish. These fish seek refuge within root systems, reed grass and among other objects in the water. They swim backwards and forwards to stay hidden despite constantly changing currents. Each fish shuttles back and forth by moving a long ribbon-like fin on the underside of its body. Uyanik et al. measured the movements of the ribbon fin under controlled conditions in the laboratory, and then used the data to create computer models of the brain and body of each fish. The models of each fish’s brain and body were quite different. To study how the brain interacts with the body, Uyanik et al. then conducted experiments reminiscent of those described in the story of Frankenstein and transplanted the brain from each computer model into the body of different model fish. These “brain swaps” had almost no effect on the model’s simulated swimming behavior. Instead, these “Frankenfish” used sensory feedback to compensate for any mismatch between their brain and body. This suggests that, for some behaviors, an animal’s brain does not need to be precisely tuned to the specific characteristics of its body. Instead, robust control of movement relies on many seemingly redundant systems that provide sensory feedback. This has implications for the field of robotics. It further suggests that when designing robots, engineers should prioritize enabling the robots to use sensory feedback to cope with unexpected events, a well-known idea in control engineering.
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Affiliation(s)
- Ismail Uyanik
- Department of Electrical and Electronics Engineering, Hacettepe University, Ankara, Turkey.,Laboratory of Computational Sensing and Robotics, Johns Hopkins University, Baltimore, United States.,Department of Biological Sciences, New Jersey Institute of Technology, Newark, United States
| | - Shahin Sefati
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, United States
| | - Sarah A Stamper
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, United States
| | - Kyoung-A Cho
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, United States
| | - M Mert Ankarali
- Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey
| | - Eric S Fortune
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, United States
| | - Noah J Cowan
- Laboratory of Computational Sensing and Robotics, Johns Hopkins University, Baltimore, United States.,Department of Mechanical Engineering, Johns Hopkins University, Baltimore, United States
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Ahn SH, Cho SH, Song JE, Kim S, Oh SS, Jung S, Cho KA, Lee TH. Caveolin-1 serves as a negative effector in senescent human gingival fibroblasts during Fusobacterium nucleatum infection. Mol Oral Microbiol 2016; 32:236-249. [PMID: 27315395 DOI: 10.1111/omi.12167] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2016] [Indexed: 12/11/2022]
Abstract
It is well established that aging is associated with increased susceptibility to infectious diseases. Fusobacterium nucleatum is a well-known bacterial species that plays a central bridging role between early and late colonizers in the human oral cavity. Further, the ability of F. nucleatum to invade gingival fibroblasts (GFs) is critical to the development of periodontal diseases. However, the mechanisms underlying the age-related infection of GFs by F. nucleatum remain unknown. We used young (fourth passage) and senescent (22nd passage) GFs to investigate the mechanisms of F. nucleatum infection in aged GFs and first observed increased invasion of F. nucleatum in senescent GFs. We also found that the co-localization of caveolin-1 (Cav-1), a protein marker of aging, with F. nucleatum and the knockdown of Cav-1 in GFs reduced F. nucleatum invasion. Additionally, F. nucleatum infection triggered the production of reactive oxygen species (ROS) through activation of NADPH oxidase in GFs, but senescent GFs exhibited significantly lower levels of NADPH oxidase activity and ROS production compared with young GFs in both the uninfected and infected conditions. Also, senescent GFs exhibited a decline in proinflammatory cytokine production and extracellular signal regulated kinase (ERK) phosphorylation following F. nucleatum infection. Interestingly, the knockdown of Cav-1 in senescent GFs increased NADPH oxidase activity and caused the upregulation of interleukin-6 and interleukin-8 and the phosphorylation of ERK. Collectively, the increased expression of Cav-1 might play a critical role in F. nucleatum invasion and could hinder the host response in senescent GFs.
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Affiliation(s)
- S H Ahn
- Department of Oral Biochemistry, Dental Science Research Institute, Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - S-H Cho
- Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, Korea
| | - J-E Song
- Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, Korea
| | - S Kim
- Department of Oral Biochemistry, Dental Science Research Institute, Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, Korea
| | - S S Oh
- Department of Oral Biochemistry, Dental Science Research Institute, Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - S Jung
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - K A Cho
- Department of Biochemistry, Chonnam National University Medical School, Gwangju, Korea
| | - T-H Lee
- Department of Oral Biochemistry, Dental Science Research Institute, Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, Korea
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Oh YS, Khil LY, Cho KA, Ryu SJ, Ha MK, Cheon GJ, Lee TS, Yoon JW, Jun HS, Park SC. A potential role for skeletal muscle caveolin-1 as an insulin sensitivity modulator in ageing-dependent non-obese type 2 diabetes: studies in a new mouse model. Diabetologia 2008; 51:1025-34. [PMID: 18408913 DOI: 10.1007/s00125-008-0993-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 02/21/2008] [Indexed: 10/22/2022]
Abstract
AIMS/HYPOTHESIS Type 2 diabetes mellitus is a common age-dependent disease. We discovered that male offspring of non-diabetic C57BL/6 and DBA/2 mice, called JYD mice, develop type 2 diabetes when they grow old. JYD mice show characteristics of insulin resistance, hyperglycaemia and hyperinsulinaemia in old age without obesity. We postulated that the mechanism of age-dependent type 2 diabetes in this model relates to caveolin-1 status in skeletal muscle, which appears to regulate insulin sensitivity in the mice. METHODS We compared insulin sensitivity in aged C57BL/6 and JYD mice using glucose and insulin tolerance tests and (18)F-fluorodeoxyglucose positron emission tomography. We also determined insulin signalling molecules and caveolin proteins using western blotting, and altered caveolin-1 levels in skeletal muscle of C57BL/6 and JYD mice using viral vector systems, to examine the effect of this on insulin sensitivity. RESULTS In 30-week-old C57BL/6 and JYD mice, the basal levels of IRS-1, Akt and peroxisome proliferator-activated receptor-gamma decreased, as did insulin-stimulated phosphorylation of Akt and insulin receptor beta. However, caveolin-1 was only increased about twofold in 30-week-old JYD mice as compared with 3-week-old mice, whereas an eightfold increase was seen in C57BL/6 mice. Downregulation of caveolin-1 production in C57BL/6 mice caused severe impairment of glucose and insulin tolerance. Upregulation of caveolin-1 in aged diabetic JYD mice significantly improved insulin sensitivity with a concomitant increase of glucose uptake in the skeletal muscle. CONCLUSIONS/INTERPRETATION The level of skeletal muscle caveolin-1 is correlated with the progression of age-dependent type 2 diabetes in JYD mice.
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Affiliation(s)
- Y S Oh
- Department of Biochemistry and Molecular Biology, Aging and Apoptosis Research Center, Seoul National University College of Medicine, 28 Yungon Dong, Chongno Ku, Seoul 110-799, South Korea
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Abstract
A decreased apoptotic response toward noxious stress is an issuing characteristic of the aging phenotype. Hydrogen peroxide or staurosporine induced apoptosis readily in young cells but not in senescent cells. We showed that focal adhesion kinase (FAK) expression and its phosphorylation at Tyr397, autophosphorylation site for focal adhesion formation, and Tyr577, Src-dependent phosphorylation site, were both increased in senescent cells. Moreover, FAK was inactivated proteolytically by apoptotic stimuli in young cells, but not in senescent cells. In addition, senescent cells whose FAK expression was downregulated by siRNA showed the increased level of apoptosis by staurosporine treatment via caspase-3 activation but not by hydrogen peroxide treatment. Interestingly dephosphorylation at Tyr577 of FAK by PP2 treatment, Src-family kinase inhibitor, induced the apoptosis by staurosporine in senescent cells but dephosphorylation at Tyr397 by downregulation of caveolin-1 was not affected. These data suggest that FAK might differently regulate apoptosis and focal adhesion formation through site-specific tyrosine phosphorylation in senescent cells.
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Affiliation(s)
- S J Ryu
- Department of Biochemistry and Molecular Biology, The Aging and Apoptosis Research Center, Seoul National University College of Medicine, Seoul, S. Korea
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Park SC, Park JS, Park WY, Cho KA, Ahn JS, Jang IS. Down-regulation of receptor-mediated endocytosis is responsible for senescence-associated hyporesponsiveness. Ann N Y Acad Sci 2002; 959:45-9. [PMID: 11976184 DOI: 10.1111/j.1749-6632.2002.tb02081.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human diploid fibroblasts (HDF) do not divide indefinitely and eventually lead to an arrest of cell division by a process termed cellular or replicative senescence. Irreversible growth arrest of senescent cells is strongly related to the attenuated response to growth factors. Recently, we reported that up-regulation of caveolin in the senescent cells is responsible for the attenuated response to growth factors. Senescent cells did not phosphorylate Erk-1/2 after EGF stimulation, whereas young cells did. In those senescent cells, we found an increased level of caveolin proteins and strong interactions between caveolin-1 and EGFR. When we overexpressed caveolin-1 in young HDF, the activation of Erk-1/2 on EGF stimulation was significantly suppressed. These results suggest that the hyporesponsiveness of senescent fibroblasts to EGF stimulation might be due to the overexpression of caveolin. In addition, the clathrin-dependent endocytosis system plays the more active and dominant role over the caveolae system. Therefore, we monitored the efficiency of clathrin-dependent receptor-mediated endocytosis in the senescent cells in order to elucidate the exact mode of the attenuated response to growth factors in the senescent cells. Using a transferrin-uptake assay and Western blot analysis of endocytosis-related proteins, we found a significant decrease of amphiphysin-1 in human diploid fibroblasts of multipassages. By adjusting the level of amphiphysin, we could modulate the efficiency of receptor-mediated endocytosis either in young or old cells toward growth factors: that is, a dominant negative mutant of amphiphysin-1 blocked the endocytosis in the young cells, while microinjection of the gene resumed its activity in the old cells. Taken together, we conclude that the loss of endocytotic activity of senescent cells is directly related to the down-regulation of amphiphysin-1 and/or up-regulation of caveolins. This opens a new field of functional recovery of the senescent cells simply through adjusting the receptor-mediated endocytosis capacity.
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Affiliation(s)
- Sang Chul Park
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, South Korea.
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Park JS, Park WY, Cho KA, Kim DI, Jhun BH, Kim SR, Park SC. Down-regulation of amphiphysin-1 is responsible for reduced receptor-mediated endocytosis in the senescent cells. FASEB J 2001; 15:1625-7. [PMID: 11427507 DOI: 10.1096/fj.00-0723fje] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- J S Park
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, South Korea
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Lee SG, Cho KA, Choi YH, Montgomery K, Lee E, Miller A, Kucherlapati R, Song K. A sequence-ready map for human chromosome 12q15-21. DNA Seq 2001; 11:353-61. [PMID: 11092752 DOI: 10.3109/10425170009033255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Construction of sequence-ready clone map is an essential step toward sequencing the human genome. We chose a region that is frequently amplified in liposarcoma between D12S350 and D12S106 in chromosome 12q15-21 to build a PAC/BAC clone contig map. This region was spanned by 4 YACs and contained 30 STS on the YAC and radiation hybrid (RH) framework maps, providing an average STS spacing of 160 kb if each YAC is approximately 1.2 Mb in size. To convert a STS-based YAC map to a STS-based contig map of bacterial clones, 22 non-polymorphic STS markers were used as probes to screen the high density gridded arrays of PAC and BAC clones by filter hybridizations, followed by assembly of clones into contigs by marker content. Contigs have been extended and joined by direct end sequencing of appropriate clones, generating new STSs and rescreening the library as necessary. Using these approaches, we have constructed 5 contigs covering the region with the largest single contig being 1.4 Mb and a final size estimation of 3.6 Mb. The map is comprised of 17 YACs, 187 PACs, 160 BACs, and 17 cosmids; onto this, 6 polymorphic, 97 non-polymorphic, 24 ESTs, and 4 gene-based markers are now placed in a unique order, providing an average resolution of approximately 28 kb. Of a total of 131 markers, 97 were developed in the present study. The sequence-ready map should provide a framework to generate complete DNA sequence and ultimately gene map of this segment of chromosome 12.
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Affiliation(s)
- S G Lee
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
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Abstract
One of the characteristics of senescent cells is unresponsiveness to external stimuli like EGF. Although they have a normal level of receptors and downstream signaling molecules, EGF cannot induce the activation of Erk kinases and DNA synthesis in senescent cells as much as in young cells. Caveolin proteins directly interact with signaling molecules including EGF receptor and suppress the activation of EGFR upon EGF stimulation. We found that Erk activation after EGF stimulation in senescent human diploid fibroblasts was down-regulated. Those senescent cells showed an increased level of three isoforms of caveolin proteins. This change seems to lie in transcriptional control in senescent cells. We also demonstrated up-regulated caveolin proteins were co-localized with EGFR proteins in detergent-insoluble fractions. From these results, we suggest that the up-regulated expression of caveolin might explain the unresponsiveness of senescent fibroblasts to EGF stimulation.
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Affiliation(s)
- W Y Park
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Korea
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Park WY, Park JS, Cho KA, Kim DI, Ko YG, Seo JS, Park SC. Up-regulation of caveolin attenuates epidermal growth factor signaling in senescent cells. J Biol Chem 2000; 275:20847-52. [PMID: 10781609 DOI: 10.1074/jbc.m908162199] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Senescent human diploid fibroblasts do not respond to growth factors like epidermal growth factor (EGF), although they have a normal level of receptors and downstream signaling molecules. To examine the mechanism of signaling attenuation, we investigated Erk activation after EGF stimulation in senescent cells. Senescent cells did not phosphorylate Erk-1/2 after EGF stimulation, whereas young cells did. In those senescent cells, we found an increased level of caveolin proteins and strong interactions between caveolin-1 and EGF receptor. Electron microscopic analysis demonstrated an increased number of caveolae structures in senescent cells. More interestingly, brain, spleen, and lung from 26-month-old rats showed substantial increases of caveolin proteins. However, in the case of p53-induced senescence, caveolin-1 was not induced, and EGF stimulation phosphorylated Erk-1/2 as much as young control cells. Finally, we overexpressed caveolin-1 in young human diploid fibroblasts in which the activation of Erk-1/2 upon EGF stimulation was significantly suppressed. These results suggest that the unresponsiveness of senescent fibroblasts to EGF stimulation may be due to the overexpression of caveolins, which seems to be independent of growth arrest and other aging phenotypes.
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Affiliation(s)
- W Y Park
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 110-799, Korea
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Kee SH, Cho KA, Kim MK, Lim BU, Chang WH, Kang JS. Disassembly of focal adhesions during apoptosis of endothelial cell line ECV304 infected with Orientia tsutsugamushi. Microb Pathog 1999; 27:265-71. [PMID: 10545254 DOI: 10.1006/mpat.1999.0304] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many bacterial pathogens induce apoptosis in their host cells. We observed the cellular effect of ECV304 cells infected with Orientia tsutsugamushi. The infected cells became rounded and floated in culture supernatant. These floating cells as well as adherent cells exhibited typical features of apoptosis, such as DNA fragmentation and TUNEL staining. As many cells detached from growth substrate, we examined the focal adhesion using the immunofluorescence assay method and observed decreased focal adhesions in heavily infected cells. As endothelial cells could undergo apoptosis by the loss of focal adhesions, this change of focal adhesions may account for the Orientia-induced apoptosis.
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Affiliation(s)
- S H Kee
- Department of Microbiology, Hallym University College of Medicine, Chunchon, 200-702, Republic of Korea
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Abstract
Endothelial cells are major targets of Orientia tsutsugamushi. To examine the consequences of the infection of endothelial cells with O. tsutsugamushi, we used human endothelial cell line ECV304. Persistent infection was established and infected cultures could be maintained for over seven months without the addition of normal cells. The heavily infected cells became round and floated in the culture medium, harboring large numbers of organisms inside them. Some of the infected ECV304 cells showed features of apoptotic cells, as determined by the terminal deoxytransferase-mediated dUTP nick end-labeling reaction and DNA fragmentation. We also found that O. tsutsugamushi increased transcription of the mRNAs of proinflammatory cytokines such as IL-6 and IL-8. These results show the first evidence of in vitro-persistent infection by O. tsutsugamushi, which may be related to in vivo persistence reported previously.
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Affiliation(s)
- M K Kim
- Department of Microbiology, Inha University College of Medicine, Inchon, Republic of Korea
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