1
|
Gonçalves PP, Stenovec M, Grácio L, Kreft M, Zorec R. Calcium-dependent subquantal peptide release from single docked lawn-resident vesicles of pituitary lactotrophs. Cell Calcium 2023; 109:102687. [PMID: 36528978 DOI: 10.1016/j.ceca.2022.102687] [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: 11/04/2022] [Revised: 12/08/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
Regulated exocytosis consists of the fusion between vesicles and the plasma membranes, leading to the formation of a narrow fusion pore through which secretions exit the vesicle lumen into the extracellular space. An increase in the cytosolic concentration of free Ca2+ ([Ca2+]i) is considered the stimulus of this process. However, whether this mechanism can be preserved in a simplified system of membrane lawns with docked secretory vesicles, devoid of cellular components, is poorly understood. Here, we studied peptide discharge from individual secretory vesicles docked at the plasma membrane, prepared from primary endocrine pituitary cells (the lactotrophs), releasing hormone prolactin. To label secretory vesicles, we transfected lactotrophs to express the fluorescent atrial natriuretic peptide (ANP.emd), previously shown to be expressed in and released from prolactin-containing vesicles. We used stimulating solutions containing different [Ca2+] to evoke vesicle peptide discharge, which appeared similar in membrane lawns and in intact stimulated lactotrophs. All vesicles examined discharged peptides in a subquantal manner, either exhibiting a unitary or sequential time course. In the membrane lawns, the unitary vesicle peptide discharge was predominant and slightly slower than that recorded in intact cells, but with a shorter delay with respect to the stimulation onset. This study revealed directly that Ca2+ triggers peptide discharge from docked single vesicles in the membrane lawns with a half-maximal response of ∼8 µM [Ca2+], consistent with previous whole-cell patch-clamp studies in endocrine cells where the rapid component of exocytosis, interpreted to represent docked vesicles, was fully activated at <10 µM [Ca2+]. Interestingly, the sequential subquantal peptide vesicle discharge indicates that fluctuations between constricted and dilated fusion pore states are preserved in membrane lawns and that fusion pore regulation appears to be an autonomously controlled process.
Collapse
Affiliation(s)
- Paula P Gonçalves
- CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Matjaž Stenovec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Zaloška 4, 1000, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia
| | - Luciano Grácio
- CRACS & INESC-TEC - Centre for Research in Advanced Computing Systems & Institute for Systems and Computer Engineering, Technology and Science, Department of Computer Science, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Zaloška 4, 1000, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia; Department of Biology, University of Ljubljana, Biotechnical Faculty, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Zaloška 4, 1000, Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia.
| |
Collapse
|
2
|
Božič D, Hočevar M, Kisovec M, Pajnič M, Pađen L, Jeran M, Bedina Zavec A, Podobnik M, Kogej K, Iglič A, Kralj-Iglič V. Stability of Erythrocyte-Derived Nanovesicles Assessed by Light Scattering and Electron Microscopy. Int J Mol Sci 2021; 22:ijms222312772. [PMID: 34884574 PMCID: PMC8657685 DOI: 10.3390/ijms222312772] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/12/2021] [Accepted: 11/22/2021] [Indexed: 12/12/2022] Open
Abstract
Extracellular vesicles (EVs) are gaining increasing amounts of attention due to their potential use in diagnostics and therapy, but the poor reproducibility of the studies that have been conducted on these structures hinders their breakthrough into routine practice. We believe that a better understanding of EVs stability and methods to control their integrity are the key to resolving this issue. In this work, erythrocyte EVs (hbEVs) were isolated by centrifugation from suspensions of human erythrocytes that had been aged in vitro. The isolate was characterised by scanning (SEM) and cryo-transmission electron microscopy (cryo-TEM), flow cytometry (FCM), dynamic/static light scattering (LS), protein electrophoresis, and UV-V spectrometry. The hbEVs were exposed to various conditions (pH (4–10), osmolarity (50–1000 mOsm/L), temperature (15–60 °C), and surfactant Triton X-100 (10–500 μM)). Their stability was evaluated by LS by considering the hydrodynamic radius (Rh), intensity of scattered light (I), and the shape parameter (ρ). The morphology of the hbEVs that had been stored in phosphate-buffered saline with citrate (PBS–citrate) at 4 °C remained consistent for more than 6 months. A change in the media properties (50–1000 mOsm/L, pH 4–10) had no significant effect on the Rh (=100–130 nm). At pH values below 6 and above 8, at temperatures above 45 °C, and in the presence of Triton X-100, hbEVs degradation was indicated by a decrease in I of more than 20%. Due to the simple preparation, homogeneous morphology, and stability of hbEVs under a wide range of conditions, they are considered to be a suitable option for EV reference material.
Collapse
Affiliation(s)
- Darja Božič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (D.B.); (M.P.); (L.P.); (M.J.)
| | - Matej Hočevar
- Department of Physics and Chemistry of Materials, Institute of Metals and Technology, SI-1000 Ljubljana, Slovenia;
| | - Matic Kisovec
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (A.B.Z.); (M.P.)
| | - Manca Pajnič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (D.B.); (M.P.); (L.P.); (M.J.)
| | - Ljubiša Pađen
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (D.B.); (M.P.); (L.P.); (M.J.)
| | - Marko Jeran
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (D.B.); (M.P.); (L.P.); (M.J.)
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
| | - Apolonija Bedina Zavec
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (A.B.Z.); (M.P.)
| | - Marjetka Podobnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (A.B.Z.); (M.P.)
| | - Ksenija Kogej
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
- Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (D.B.); (M.P.); (L.P.); (M.J.)
- Correspondence: ; Tel.: +386-4172-0766
| |
Collapse
|
3
|
Angelico M, Mogavero L, Baiocchi L, Nistri A, Gandin C. Dissolution of human cholesterol gallstones in bile salt/lecithin mixtures: effect of bile salt hydrophobicity and various pHs. Scand J Gastroenterol 1995; 30:1178-85. [PMID: 9053971 DOI: 10.3109/00365529509101628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Unconjugated bile salts currently available for gallstone dissolution are poorly effective. We evaluated in vitro the litholytic potency of taurine-amidated bile salts against human cholesterol gallstones. METHODS Seventy radiolucent gallstones with similar size and composition (cholesterol content, 70.1 +/- 0.9%) from a single patient were incubated in model biles composed of 100 mM of either taurochenodeoxycholate (TCDC), taurocholate (TC), taurohyodeoxycholate (THDC) or tauroursodeoxycholate (TUDC) and of 45 mM egg yolk lecithin in saline buffered with tris/HCl (at pHs 7 and 8) or phosphate (at pHs 4 and 6). Biles (total lipids, 10 g/dl; cholesterol saturation, 99%) were incubated at 37 degrees C for 40 days. Gallstones were periodically weighed and returned to the dissolution vials, and the biliary cholesterol concentration was monitored. RESULTS Model biles remained optically clear during the initial 48 h of incubation. Then, biles containing THDC and TUDC, but not those with TC and TCDC, became progressively turbid until, after several days, a white precipitate surrounded the residual stone. Abundant liquid crytalline droplets were observed at polarizing microscopy in biles containing TUDC and THDC. Gallstone dissolution was closely related to cholesterol solubilization and decreased in the order TCDC > THDC > or = TC > TUDC, being highest at pH 8. At the physiologic pH of 7 THDC was more litholythic than TC. CONCLUSIONS In vitro, the litholytic potency of bile salts on cholesterol gallstones primarily depends on their hydrophobicity. THDC is a new potential gallstone-dissolving agent, deserving in vivo studies.
Collapse
Affiliation(s)
- M Angelico
- Dept. of Public Health, Tor Vergata University, Rome, Italy
| | | | | | | | | |
Collapse
|
4
|
Moreau P, Cassagne C. Phospholipid trafficking and membrane biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1197:257-90. [PMID: 7819268 DOI: 10.1016/0304-4157(94)90010-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- P Moreau
- URA 1811 CNRS, IBGC, University of Bordeaux II, France
| | | |
Collapse
|
5
|
|
6
|
Jacobsohn MK, Bauder S, Pine SR, Jacobsohn GM. Cholesterol limits estrogen uptake by liposomes and erythrocyte membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1195:131-40. [PMID: 7918555 DOI: 10.1016/0005-2736(94)90019-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Multilamellar vesicles (MLV) were prepared from phospholipids with and without cholesterol in equimolar amounts and [4-14C]estradiol. Unincorporated estrogen was removed by petroleum ether extraction or by aqueous buffer washes. In either case, cholesterol-containing vesicles incorporated one-half the estradiol as vesicles without sterol. Addition of estradiol to preformed vesicles followed by buffer washes showed that vesicles without cholesterol invariably retained more estradiol than those with the sterol. Reduction of the cholesterol content to one-half increased estradiol incorporation. The pattern of estradiol removal from MLV with successive buffer washes indicated that much of the steroid associated with cholesterol-containing vesicles was superficially bound to the membrane but vesicles without cholesterol incorporated the estrogen into the bilayer structure. To test the role of cholesterol in limiting the uptake of an estrogen by cells, right-side out resealed ghosts of ox erythrocytes were prepared. They were partially depleted of cholesterol by exposure to small unilamellar vesicles of dioleoylphosphatidyl choline. A decrease in cholesterol content correlates with an increase in estradiol uptake by red cell ghosts. The experiments described point to a central role of cholesterol in limiting the uptake of steroids. The loss of cholesterol of steroid producing cells caused by tropic hormones may be key to their mode of action in promoting secretion of steroid hormones. Likewise, the long-term genomic responses of steroid target cells may depend upon their cholesterol content and the ease by which the steroid can penetrate the membrane barrier.
Collapse
Affiliation(s)
- M K Jacobsohn
- Department of Biological Chemistry, Hahnemann University, Philadelphia, PA 19102
| | | | | | | |
Collapse
|
7
|
Hazel JR, McKinley SJ, Williams EE. Thermal adaptation in biological membranes: interacting effects of temperature and pH. J Comp Physiol B 1992. [DOI: 10.1007/bf00296639] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
8
|
Jacobsohn MK, Lehman MM, Jacobsohn GM. Cell membranes and multilamellar vesicles: influence of pH on solvent induced damage. Lipids 1992; 27:694-700. [PMID: 1487967 DOI: 10.1007/bf02536027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pigment leakage from sheep and horse erythrocytes and from red beet tissue induced by non-polar solvents was determined as a function of pH. The results were compared to disruption of multilamellar vesicles (MLV) composed of phospholipids with equimolar cholesterol under identical conditions of solvent exposure and pH. Solvent access to cholesterol was used to measure vesicle disruption. MLV were made from 1,2-dioleoyl phosphatidylethanolamine, sphingomyelin (SP) and various phosphatidylcholines to simulate the major lipid components of membranes. Pigment leakage from erythrocytes caused by petroleum hydrocarbon (b.p. 60-80 degrees C) was maximal at pH 2-4 and at pH 10, but minimal at pH 6.8; alcohols caused less pigment leakage than petroleum hydrocarbon. Beta-cyanin leakage from beet tissue induced by petroleum hydrocarbon was maximal at pH 2, with very little leakage at pH 4, 6.6 and pH 10. Alcohols caused minimal damage to beet tissue above pH 2. Cholesterol removal by petroleum hydrocarbon from MLV of mixed lipid composition was maximal at pH 2-4, reduced at pH 6.8 and minimal at pH 10. Lipid mixtures in which fatty acyl side chains of one phospholipid were of a different length than the other lost more sterol than mixtures in which the acyl side chains were of identical chain length. MLV with more than 25% SP lost more sterol than those with less or no SP. Results show that in mixtures of phospholipids, SP exposes the hydrocarbon phase of a bilayer to solvent extraction, a property that was also observed in native membranes.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- M K Jacobsohn
- Department of Biological Chemistry, Hahnemann University, Philadelphia, Pennsylvania 19102
| | | | | |
Collapse
|
9
|
Bonomo EA, Matsuura JE, Swaney JB. Properties of phosphatidylethanolamine-containing phospholipid-apolipoprotein complexes modified by lecithin-cholesterol acyltransferase. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1082:265-74. [PMID: 2029546 DOI: 10.1016/0005-2760(91)90202-s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effect of the inclusion of phosphatidylethanolamine (PE), a phospholipid with unusual packing properties, on the substrate properties of protein-lipid complexes toward lecithin-cholesterol acyltransferase (LCAT) has been studied. Recombinant particles of apolipoprotein A-I with dimyristoylphosphatidylcholine (DMPC), dilauroylphosphatidylethanolamine (DLPE) and cholesterol were prepared at a molar ratio of 1:140:14 (A-I/DMPC/cholesterol) or 1:70:70:14 (A-I/DMPC/DLPE/cholesterol); the efficiency of cholesterol incorporation into complexes containing phosphatidylethanolamine was found to be very pH-dependent, with enhanced cholesterol incorporation at elevated pH values. By incubating the complexes with either purified human LCAT or the d greater than 1.21 g/ml fraction of rat serum as a source of LCAT activity, it was found that a high degree of cholesterol esterification could be achieved with either complex; however, the DLPE-containing complex possessed a much smaller Stokes' diameter than the DMPC-only particle despite compositional similarities between these complexes. With respect to particle diameter the DLPE-containing particles behaved more like complexes prepared with egg yolk lecithin than did complexes prepared with DMPC alone. When human LDL was added to the incubations to provide a source of additional cholesterol, the products were markedly different. Concomitant with an increased cholesteryl ester core was an increase in the protein stoichiometry in both types of particles, from 2 to 3 or 4 apo A-I per particle. The proportion of DLPE to DMPC in the products was reduced from 1:1 to 0.3:1, reflecting a preferential hydrolysis of PE by LCAT, and the Stokes' diameters of the DMPC-only and the DLPE-containing complexes were closely similar. We conclude that the presence of elevated proportions of certain phospholipid species may significantly alter both the physical properties of the particles and their substrate properties with regard to reactions with enzymes of lipid metabolism.
Collapse
Affiliation(s)
- E A Bonomo
- Department of Biological Chemistry, Hahnemann University, Philadelphia, PA 19102
| | | | | |
Collapse
|
10
|
Moreau P, Rodriguez M, Cassagne C, Morré DM, Morré DJ. Trafficking of lipids from the endoplasmic reticulum to the Golgi apparatus in a cell-free system from rat liver. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(20)64325-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
11
|
Maerker G, Jones KC. Unusual product ratios resulting from the gamma-irradiation of cholesterol in liposomes. Lipids 1991; 26:139-44. [PMID: 2051896 DOI: 10.1007/bf02544008] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cholesterol in aqueous suspensions of multilamellar vesicles (MLV) was exposed to gamma-irradiation (0.5-10 kGy) at 0-4 degrees C. Cholesterol oxidation products resulting from the irradiation were isolated by dry column extraction followed by preparative thin-layer chromatography (TLC) and were quantitated by on-column gas chromatography (GC). The ratio of 7-ketocholesterol/cholesterol 5,6-epoxides generated by irradiation was less than one, much lower than the ratio of ten commonly produced by autoxidation. Irradiation also produced relatively higher amounts of 7-hydroxycholesterol than did autoxidation. These unique product ratios may be suitable indicators of past exposure to irradiation.
Collapse
Affiliation(s)
- G Maerker
- U.S. Department of Agriculture, Eastern Regional Research Center, Philadelphia, Pennsylvania 19118
| | | |
Collapse
|
12
|
|