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  1. Article ; Online: Real-Time Autophagic Flux Measurements in Live Cells Using a Novel Fluorescent Marker DAPRed.

    Sipos, Arnold / Kim, Kwang-Jin / Alvarez, Juan R / Crandall, Edward D

    Bio-protocol

    2024  Volume 14, Issue 5, Page(s) e4949

    Abstract: Autophagy is a conserved homeostatic mechanism involved in cellular homeostasis and many disease processes. Although it was first described in yeast cells undergoing starvation, we have learned over the years that autophagy gets activated in many stress ... ...

    Abstract Autophagy is a conserved homeostatic mechanism involved in cellular homeostasis and many disease processes. Although it was first described in yeast cells undergoing starvation, we have learned over the years that autophagy gets activated in many stress conditions and during development and aging in mammalian cells. Understanding the fundamental mechanisms underlying autophagy effects can bring us closer to better insights into the pathogenesis of many disease conditions (e.g., cardiac muscle necrosis, Alzheimer's disease, and chronic lung injury). Due to the complex and dynamic nature of the autophagic processes, many different techniques (e.g., western blotting, fluorescent labeling, and genetic modifications of key autophagy proteins) have been developed to delineate autophagy effects. Although these methods are valid, they are not well suited for the assessment of time-dependent autophagy kinetics. Here, we describe a novel approach: the use of DAPRed for autophagic flux measurement via live cell imaging, utilizing A549 cells, that can visualize and quantify autophagic flux in real time in single live cells. This approach is relatively straightforward in comparison to other experimental procedures and should be applicable to any in vitro cell/tissue models. Key features • Allows real-time qualitative imaging of autophagic flux at single-cell level. • Primary cells and cell lines can also be utilized with this technique. • Use of confocal microscopy allows visualization of autophagy without disturbing cellular functions.
    Language English
    Publishing date 2024-03-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2833269-6
    ISSN 2331-8325 ; 2331-8325
    ISSN (online) 2331-8325
    ISSN 2331-8325
    DOI 10.21769/BioProtoc.4949
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells.

    Sipos, Arnold / Kim, Kwang-Jin / Sioutas, Constantinos / Crandall, Edward D

    Autophagy reports

    2023  Volume 2, Issue 1

    Abstract: Autophagy, a homeostatic mechanism, is crucial in maintaining normal cellular function. Although dysregulation of autophagic processes is recognized in certain diseases, it is unknown how maintenance of cellular homeostasis might be affected by the ... ...

    Abstract Autophagy, a homeostatic mechanism, is crucial in maintaining normal cellular function. Although dysregulation of autophagic processes is recognized in certain diseases, it is unknown how maintenance of cellular homeostasis might be affected by the kinetics of autophagic activity in response to various stimuli. In this study, we assessed those kinetics in lung adenocarcinoma (A549) cells in response to exposure to nanoparticles (NP) and/or Rapamycin. Since NP are known to induce autophagy, we wished to determine if this phenomenon could be a driver of the harmful effects seen in lung tissues exposed to air pollution. A549 cells were loaded with a fluorescent marker (DAPRed) that labels autophagosomes and autolysosomes. Autophagic activity was assessed based on the fluorescence intensity of DAPRed measured over the entire cell volume of live single cells using confocal laser scanning microscopy (CLSM). Autophagic activity over time was determined during exposure of A549 cells to single agents (50 nM Rapamycin; 80 μg/mL, 20 nm carboxylated polystyrene NP (PNP); or, 1 μg/mL ambient ultrafine particles (UFP) (<180 nm)), or double agents (Rapamycin + PNP or Rapamycin + UFP; concomitant and sequential), known to stimulate autophagy. Autophagic activity increased in all experimental modalities, including both single agent and double agent exposures, and reached a steady state in all cases ~2 times control from ~8 to 24 hrs, suggesting the presence of an upper limit to autophagic capacity. These results are consistent with the hypothesis that environmental stressors might exert their harmful effects, at least in part, by limiting available autophagic response to additional stimulation, thereby making nanoparticle-exposed cells more susceptible to secondary injury due to autophagic overload.
    Language English
    Publishing date 2023-03-15
    Publishing country United States
    Document type Journal Article
    ISSN 2769-4127
    ISSN (online) 2769-4127
    DOI 10.1080/27694127.2023.2186568
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Evidence for Nanoparticle-Induced Lysosomal Dysfunction in Lung Adenocarcinoma (A549) Cells.

    Sipos, Arnold / Kim, Kwang-Jin / Sioutas, Constantinos / Crandall, Edward D

    International journal of molecular sciences

    2019  Volume 20, Issue 21

    Abstract: Background: Polystyrene nanoparticles (PNP) are taken up by primary rat alveolar epithelial cell monolayers (RAECM) in a time-, dose-, and size-dependent manner without involving endocytosis. Internalized PNP in RAECM activate autophagy, are delivered ... ...

    Abstract Background: Polystyrene nanoparticles (PNP) are taken up by primary rat alveolar epithelial cell monolayers (RAECM) in a time-, dose-, and size-dependent manner without involving endocytosis. Internalized PNP in RAECM activate autophagy, are delivered to lysosomes, and undergo [Ca
    Methods: After exposure to PNP or ambient pollution particles (PM0.2), live single A549 cells were studied using confocal laser scanning microscopy. PNP uptake and egress were investigated and activation of autophagy was confirmed by immunolabeling with LC3-II and LC3-GFP transduction/colocalization with PNP. Mitochondrial membrane potential, mitophagy, and lysosomal membrane permeability (LMP) were assessed in the presence/absence of apical nanoparticle (NP) exposure.
    Results: PNP uptake into A549 cells decreased in the presence of cytochalasin D, an inhibitor of macropinocytosis. PNP egress was not affected by increased cytosolic [Ca
    Conclusions: Interactions between NP and A549 cells involve complex cellular processes leading to lysosomal dysfunction, which may provide opportunities for improved nanoparticle-based therapeutic approaches to lung cancer management.
    MeSH term(s) Adenocarcinoma of Lung/metabolism ; Autophagy ; Cell Line, Tumor ; Humans ; Lung Neoplasms/metabolism ; Lysosomes/metabolism ; Nanoparticles/chemistry ; Nanoparticles/metabolism ; Pinocytosis ; Polystyrenes/chemistry
    Chemical Substances Polystyrenes
    Language English
    Publishing date 2019-10-23
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms20215253
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  4. Article ; Online: Biokinetic modeling of nanoparticle interactions with lung alveolar epithelial cells: uptake, intracellular processing, and egress.

    Chen, Wenbo / D'Argenio, David Z / Sipos, Arnold / Kim, Kwang-Jin / Crandall, Edward D

    American journal of physiology. Regulatory, integrative and comparative physiology

    2020  Volume 320, Issue 1, Page(s) R36–R43

    Abstract: Studies on health effects of engineered nanomaterials (ENMs) in the lung have provided information on ENM toxicity and translocation across airway and alveolar epithelial barriers. Various inhaled ENMs (e.g., gold and iridium nanoparticles) have been ... ...

    Abstract Studies on health effects of engineered nanomaterials (ENMs) in the lung have provided information on ENM toxicity and translocation across airway and alveolar epithelial barriers. Various inhaled ENMs (e.g., gold and iridium nanoparticles) have been reported to partially cross the air-blood barrier in the lung, enter the vasculature, and distribute in several end organs, including the heart, liver, spleen, and kidney. Using an in vitro primary rat alveolar epithelial cell (AEC) monolayer model, we reported transport rates of relatively nontoxic polystyrene nanoparticles (PNPs), which appear to be taken up via nonendocytic processes into AECs. PNPs internalized into cytoplasm then trigger autophagy, followed by delivery of PNPs from autophagosomes into lysosomes, from where PNPs are exocytosed. We used the data from these experiments to perform biokinetic modeling that incorporates the processes associated with internalization and intracellular distribution of PNPs, autophagy, lysosomal exocytosis of PNPs, and several putative mechanisms of action that extend our previous understanding of AEC processing of PNPs. Results suggest that entry of PNPs into AECs, subsequent activation of autophagy by cytosolic PNPs, accumulation of PNPs in lysosomes, and lysosomal exocytosis are interwoven by proposed regulatory mechanisms.
    MeSH term(s) Alveolar Epithelial Cells/metabolism ; Animals ; Autophagosomes/metabolism ; Autophagy ; Biological Transport ; Cells, Cultured ; Exocytosis ; Kinetics ; Lysosomes/metabolism ; Models, Biological ; Nanoparticles ; Polystyrenes/chemistry ; Polystyrenes/metabolism ; Rats
    Chemical Substances Polystyrenes
    Language English
    Publishing date 2020-10-21
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 603839-6
    ISSN 1522-1490 ; 0363-6119
    ISSN (online) 1522-1490
    ISSN 0363-6119
    DOI 10.1152/ajpregu.00184.2020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Alveolar epithelial cell processing of nanoparticles activates autophagy and lysosomal exocytosis.

    Sipos, Arnold / Kim, Kwang-Jin / Chow, Robert H / Flodby, Per / Borok, Zea / Crandall, Edward D

    American journal of physiology. Lung cellular and molecular physiology

    2018  Volume 315, Issue 2, Page(s) L286–L300

    Abstract: Using confocal microscopy, we quantitatively assessed uptake, processing, and egress of near-infrared (NIR)-labeled carboxylated polystyrene nanoparticles (PNP) in live alveolar epithelial cells (AEC) during interactions with primary rat AEC monolayers ( ... ...

    Abstract Using confocal microscopy, we quantitatively assessed uptake, processing, and egress of near-infrared (NIR)-labeled carboxylated polystyrene nanoparticles (PNP) in live alveolar epithelial cells (AEC) during interactions with primary rat AEC monolayers (RAECM). PNP fluorescence intensity (content) and colocalization with intracellular vesicles in a cell were determined over the entire cell volume via z stacking. Isotropic cuvette-based microfluorimetry was used to determine PNP concentration ([PNP]) from anisotropic measurements of PNP content assessed by confocal microscopy. Results showed that PNP uptake kinetics and steady-state intracellular content decreased as diameter increased from 20 to 200 nm. For 20-nm PNP, uptake rate and steady-state intracellular content increased with increased apical [PNP] but were unaffected by inhibition of endocytic pathways. Intracellular PNP increasingly colocalized with autophagosomes and/or lysosomes over time. PNP egress exhibited fast Ca
    MeSH term(s) Alveolar Epithelial Cells/metabolism ; Animals ; Autophagy/drug effects ; Drug Carriers/chemistry ; Drug Carriers/pharmacokinetics ; Drug Carriers/pharmacology ; Exocytosis/drug effects ; Lysosomes/metabolism ; Male ; Nanoparticles/chemistry ; Particle Size ; Polystyrenes/chemistry ; Polystyrenes/pharmacokinetics ; Polystyrenes/pharmacology ; Rats ; Rats, Sprague-Dawley
    Chemical Substances Drug Carriers ; Polystyrenes
    Language English
    Publishing date 2018-05-03
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1013184-x
    ISSN 1522-1504 ; 1040-0605
    ISSN (online) 1522-1504
    ISSN 1040-0605
    DOI 10.1152/ajplung.00108.2018
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  6. Article ; Online: A high-powered view of the filtration barrier.

    Peti-Peterdi, János / Sipos, Arnold

    Journal of the American Society of Nephrology : JASN

    2010  Volume 21, Issue 11, Page(s) 1835–1841

    Abstract: Multiphoton excitation fluorescence microscopy is a powerful noninvasive imaging technique for the deep optical sectioning of living tissues. Its application in several intact tissues is a significant advance in our understanding of organ function, ... ...

    Abstract Multiphoton excitation fluorescence microscopy is a powerful noninvasive imaging technique for the deep optical sectioning of living tissues. Its application in several intact tissues is a significant advance in our understanding of organ function, including renal pathophysiological mechanisms. The glomerulus, the filtering unit in the kidney, is one good example of a relatively inaccessible and complex structure, with cell types that are otherwise difficult to study at high resolution in their native environment. In this article, we address the application, advantages, and limitations of this imaging technology for the study of the glomerular filtration barrier and the controversy it recently generated regarding the glomerular filtration of macromolecules. More advanced and accurate multiphoton determinations of the glomerular sieving coefficient that are presented here dismiss previous claims on the filtration of nephrotic levels of albumin. The sieving coefficient of 70-kD dextran was found to be around 0.001. Using a model of focal segmental glomerulosclerosis, increased filtration barrier permeability is restricted only to areas of podocyte damage, consistent with the generally accepted role of podocytes and the glomerular origin of albuminuria. Time-lapse imaging provides new details and important in vivo confirmation of the dynamics of podocyte movement, shedding, replacement, and the role of the parietal epithelial cells and Bowman's capsule in the pathology of glomerulosclerosis.
    MeSH term(s) Animals ; Cell Membrane Permeability/physiology ; Cell Movement/physiology ; Disease Models, Animal ; Glomerular Filtration Rate/physiology ; Glomerulosclerosis, Focal Segmental/pathology ; Glomerulosclerosis, Focal Segmental/physiopathology ; Kidney Glomerulus/pathology ; Kidney Glomerulus/physiopathology ; Microscopy, Fluorescence, Multiphoton/methods ; Podocytes/pathology ; Podocytes/physiology ; Rats ; Rats, Inbred Strains
    Language English
    Publishing date 2010-06-24
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1085942-1
    ISSN 1533-3450 ; 1046-6673
    ISSN (online) 1533-3450
    ISSN 1046-6673
    DOI 10.1681/ASN.2010040378
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  7. Article ; Online: Direct demonstration of tubular fluid flow sensing by macula densa cells.

    Sipos, Arnold / Vargas, Sarah / Peti-Peterdi, János

    American journal of physiology. Renal physiology

    2010  Volume 299, Issue 5, Page(s) F1087–93

    Abstract: Macula densa (MD) cells in the cortical thick ascending limb (cTAL) detect variations in tubular fluid composition and transmit signals to the afferent arteriole (AA) that control glomerular filtration rate [tubuloglomerular feedback (TGF)]. Increases in ...

    Abstract Macula densa (MD) cells in the cortical thick ascending limb (cTAL) detect variations in tubular fluid composition and transmit signals to the afferent arteriole (AA) that control glomerular filtration rate [tubuloglomerular feedback (TGF)]. Increases in tubular salt at the MD that normally parallel elevations in tubular fluid flow rate are well accepted as the trigger of TGF. The present study aimed to test whether MD cells can detect variations in tubular fluid flow rate per se. Calcium imaging of the in vitro microperfused isolated JGA-glomerulus complex dissected from mice was performed using fluo-4 and fluorescence microscopy. Increasing cTAL flow from 2 to 20 nl/min (80 mM [NaCl]) rapidly produced significant elevations in cytosolic Ca(2+) concentration ([Ca(2+)](i)) in AA smooth muscle cells [evidenced by changes in fluo-4 intensity (F); F/F(0) = 1.45 ± 0.11] and AA vasoconstriction. Complete removal of the cTAL around the MD plaque and application of laminar flow through a perfusion pipette directly to the MD apical surface essentially produced the same results even when low (10 mM) or zero NaCl solutions were used. Acetylated α-tubulin immunohistochemistry identified the presence of primary cilia in mouse MD cells. Under no flow conditions, bending MD cilia directly with a micropipette rapidly caused significant [Ca(2+)](i) elevations in AA smooth muscle cells (fluo-4 F/F(0): 1.60 ± 0.12) and vasoconstriction. P2 receptor blockade with suramin significantly reduced the flow-induced TGF, whereas scavenging superoxide with tempol did not. In conclusion, MD cells are equipped with a tubular flow-sensing mechanism that may contribute to MD cell function and TGF.
    MeSH term(s) Aniline Compounds ; Animals ; Body Fluids/physiology ; Cilia/physiology ; Fluorescent Dyes ; Immunohistochemistry ; In Vitro Techniques ; Juxtaglomerular Apparatus/cytology ; Juxtaglomerular Apparatus/physiology ; Kidney Cortex/cytology ; Kidney Cortex/physiology ; Kidney Glomerulus/physiology ; Kidney Tubules/physiology ; Mechanoreceptors/physiology ; Mice ; Mice, Inbred C57BL ; Nephrons/physiology ; Perfusion ; Signal Transduction/physiology ; Sodium Chloride/pharmacology ; Xanthenes
    Chemical Substances Aniline Compounds ; Fluo 4 ; Fluorescent Dyes ; Xanthenes ; Sodium Chloride (451W47IQ8X)
    Language English
    Publishing date 2010-08-18
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 603837-2
    ISSN 1522-1466 ; 0363-6127
    ISSN (online) 1522-1466
    ISSN 0363-6127
    DOI 10.1152/ajprenal.00469.2009
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  8. Article: Multiphoton imaging of renal regulatory mechanisms.

    Peti-Peterdi, János / Toma, Ildikó / Sipos, Arnold / Vargas, Sarah L

    Physiology (Bethesda, Md.)

    2009  Volume 24, Page(s) 88–96

    Abstract: Most physiological functions of the kidneys, including the clearance of metabolic waste products, maintenance of body fluid, electrolyte homeostasis, and blood pressure, are achieved by complex interactions between multiple renal cell types and ... ...

    Abstract Most physiological functions of the kidneys, including the clearance of metabolic waste products, maintenance of body fluid, electrolyte homeostasis, and blood pressure, are achieved by complex interactions between multiple renal cell types and previously inaccessible structures in many organ parts that have been difficult to study. Multiphoton fluorescence microscopy offers a state-of-the-art imaging technique for deep optical sectioning of living tissues and organs with minimal deleterious effects. Dynamic regulatory processes and multiple functions in the intact kidney can be quantitatively visualized in real time, noninvasively, and with submicron resolution. This article reviews innovative multiphoton imaging technologies and their applications that provided the most complex, immediate, and dynamic portrayal of renal function-clearly depicting as well as analyzing the components and mechanisms involved in renal (patho)physiology.
    MeSH term(s) Animals ; Biological Transport, Active ; Humans ; Kidney/anatomy & histology ; Kidney/physiology ; Kidney Glomerulus/anatomy & histology ; Kidney Glomerulus/physiology ; Kidney Tubules/physiology ; Microscopy, Fluorescence, Multiphoton ; Renin-Angiotensin System/physiology
    Language English
    Publishing date 2009-04-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2158667-6
    ISSN 1548-9221 ; 1548-9213
    ISSN (online) 1548-9221
    ISSN 1548-9213
    DOI 10.1152/physiol.00001.2009
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  9. Article ; Online: From in vitro to in vivo: imaging from the single cell to the whole organism.

    Kang, Jung Julie / Toma, Ildiko / Sipos, Arnold / Peti-Peterdi, Janos

    Current protocols in cytometry

    2008  Volume Chapter 12, Page(s) Unit 12.12

    Abstract: This unit addresses the applications of fluorescence microscopy and quantitative imaging to study multiple physiological variables of living tissue. Protocols are presented for fluorescence-based investigations ranging from in vitro cell and tissue ... ...

    Abstract This unit addresses the applications of fluorescence microscopy and quantitative imaging to study multiple physiological variables of living tissue. Protocols are presented for fluorescence-based investigations ranging from in vitro cell and tissue approaches to in vivo imaging of intact organs. These include the measurement of cytosolic parameters both in vitro and in vivo (such as calcium, pH, and nitric oxide), dynamic cellular processes (renin granule exocytosis), FRET-based real-time assays of enzymatic activity (renin), physiological processes (vascular contraction, membrane depolarization), and whole organ functional parameters (blood flow, glomerular filtration). Multi-photon microscopy is ideal for minimally invasive and undisruptive deep optical sectioning of the living tissue, which translates into ultra-sensitive real-time measurement of these parameters with high spatial and temporal resolution. With the combination of cell and tissue cultures, microperfusion techniques, and whole organ or animal models, fluorescence imaging provides unmatched versatility for biological and medical studies of the living organism.
    MeSH term(s) Animals ; Cytological Techniques ; Diagnostic Imaging/methods ; Fluorescent Dyes ; Humans ; Methods ; Microscopy, Fluorescence/methods ; Signal Transduction ; Spectrometry, Fluorescence/methods
    Chemical Substances Fluorescent Dyes
    Language English
    Publishing date 2008-04
    Publishing country United States
    Document type Journal Article
    ISSN 1934-9300
    ISSN (online) 1934-9300
    DOI 10.1002/0471142956.cy1212s44
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  10. Article: Nanomaterial interactions with and trafficking across the lung alveolar epithelial barrier: implications for health effects of air-pollution particles.

    Yacobi, Nazanin R / Fazllolahi, Farnoosh / Kim, Yong Ho / Sipos, Arnold / Borok, Zea / Kim, Kwang-Jin / Crandall, Edward D

    Air quality, atmosphere, & health

    2014  Volume 4, Issue 1, Page(s) 65–78

    Abstract: Studies on the health effects of air-pollution particles suggest that injury may result from inhalation of airborne ultrafine particles (<100 nm in diameter). Engineered nanomaterials (<100 nm in at least one dimension) may also be harmful if inhaled. ... ...

    Abstract Studies on the health effects of air-pollution particles suggest that injury may result from inhalation of airborne ultrafine particles (<100 nm in diameter). Engineered nanomaterials (<100 nm in at least one dimension) may also be harmful if inhaled. Nanomaterials deposited on the respiratory epithelial tract are thought to cross the air-blood barrier, especially via the expansive alveolar region, into the systemic circulation to reach end organs (e.g., myocardium, liver, pancreas, kidney, and spleen). Since ambient ultrafine particles are difficult to track, studies of defined engineered nanomaterials have been used to obtain valuable information on how nanomaterials interact with and traffic across the air-blood barrier of mammalian lungs. Since specific mechanistic information on how nanomaterials interact with the lung is difficult to obtain using in vivo or ex vivo lungs due to their complex anatomy, in vitro alveolar epithelial models have been of considerable value in determining nanomaterial-lung interactions. In this review, we provide information on mechanisms underlying lung alveolar epithelial injury caused by various nanomaterials and on nanomaterial trafficking across alveolar epithelium that may lead to end-organ injury.
    Language English
    Publishing date 2014-12-16
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2424084-9
    ISSN 1873-9326 ; 1873-9318
    ISSN (online) 1873-9326
    ISSN 1873-9318
    DOI 10.1007/s11869-010-0098-z
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