1
|
Mangini M, Limatola N, Ferrara MA, Coppola G, Chun JT, De Luca AC, Santella L. Application of Raman spectroscopy to the evaluation of F-actin changes in sea urchin eggs at fertilization. ZYGOTE 2024; 32:38-48. [PMID: 38050697 DOI: 10.1017/s0967199423000552] [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] [Indexed: 12/06/2023]
Abstract
The actin filaments on the surface of echinoderm oocytes and eggs readily undergo massive reorganization during meiotic maturation and fertilization. In sea urchin eggs, the actin cytoskeletal response to the fertilizing sperm is fast enough to accompany Ca2+ signals and to guide sperm's entry into the egg. Although recent work using live cell imaging technology confirmed changes in the actin polymerization status in fertilized eggs, as was previously shown using light and electron microscopy, it failed to provide experimental evidence of F-actin depolymerization a few seconds after insemination, which is concurrent with the sperm-induced Ca2+ release. In the present study, we applied Raman microspectroscopy to tackle this issue by examining the spectral profiles of the egg's subplasmalemmal regions before and after treating the eggs with actin drugs or fertilizing sperm. At both early (15 s) and late (15 min) time points after fertilization, specific peak shifts in the Raman spectra revealed change in the actin structure, and Raman imaging detected the cytoskeletal changes corresponding to the F-actin reorganization visualized with LifeAct-GFP in confocal microscopy. Our observation suggests that the application of Raman spectroscopy, which does not require microinjection of fluorescent probes and exogenous gene expression, may serve as an alternative or even advantageous method in disclosing rapid subtle changes in the subplasmalemmal actin cytoskeleton that are difficult to resolve.
Collapse
Affiliation(s)
- Maria Mangini
- Institute of Experimental Endocrinology and Oncology 'G. Salvatore', Second Unit, National Research Council, 80131Naples, Italy
| | - Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121Naples, Italy
| | - Maria Antonietta Ferrara
- Institute of Applied Sciences and Intelligent Systems 'E. Caianiello', Unit of Naples, National Research Council, 80131Naples, Italy
| | - Giuseppe Coppola
- Institute of Applied Sciences and Intelligent Systems 'E. Caianiello', Unit of Naples, National Research Council, 80131Naples, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121Naples, Italy
| | - Anna Chiara De Luca
- Institute of Experimental Endocrinology and Oncology 'G. Salvatore', Second Unit, National Research Council, 80131Naples, Italy
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121Naples, Italy
| |
Collapse
|
2
|
Limatola N, Chun JT, Chiba K, Santella L. Dithiothreitol Affects the Fertilization Response in Immature and Maturing Starfish Oocytes. Biomolecules 2023; 13:1659. [PMID: 38002342 PMCID: PMC10669828 DOI: 10.3390/biom13111659] [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: 09/25/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
Immature starfish oocytes isolated from the ovary are susceptible to polyspermy due to the structural organization of the vitelline layer covering the oocyte plasma membrane, as well as the distribution and biochemical properties of the actin cytoskeleton of the oocyte cortex. After the resumption of the meiotic cycle of the oocyte triggered by the hormone 1-methyladenine, the maturing oocyte reaches fertilizable conditions to be stimulated by only one sperm with a normal Ca2+ response and cortical reaction. This cytoplasmic ripening of the oocyte, resulting in normal fertilization and development, is due to the remodeling of the cortical actin cytoskeleton and germinal vesicle breakdown (GVBD). Since disulfide-reducing agents such as dithiothreitol (DTT) are known to induce the maturation and GVBD of oocytes in many species of starfish, we analyzed the pattern of the fertilization response displayed by Astropecten aranciacus oocytes pre-exposed to DTT with or without 1-MA stimulation. Short treatment of A. aranciacus immature oocytes with DTT reduced the rate of polyspermic fertilization and altered the sperm-induced Ca2+ response by changing the morphology of microvilli, cortical granules, and biochemical properties of the cortical F-actin. At variance with 1-MA, the DTT treatment of immature starfish oocytes for 70 min did not induce GVBD. On the other hand, the DTT treatment caused an alteration in microvilli morphology and a drastic depolymerization of the cortical F-actin, which impaired the sperm-induced Ca2+ response at fertilization and the subsequent embryonic development.
Collapse
Affiliation(s)
- Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy;
| | - Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo 112-8610, Japan;
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
| |
Collapse
|
3
|
The Therapeutic and Diagnostic Potential of Phospholipase C Zeta, Oocyte Activation, and Calcium in Treating Human Infertility. Pharmaceuticals (Basel) 2023; 16:ph16030441. [PMID: 36986540 PMCID: PMC10056371 DOI: 10.3390/ph16030441] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/19/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023] Open
Abstract
Oocyte activation, a fundamental event during mammalian fertilisation, is initiated by concerted intracellular patterns of calcium (Ca2+) release, termed Ca2+ oscillations, predominantly driven by testis-specific phospholipase C zeta (PLCζ). Ca2+ exerts a pivotal role in not just regulating oocyte activation and driving fertilisation, but also in influencing the quality of embryogenesis. In humans, a failure of Ca2+ release, or defects in related mechanisms, have been reported to result in infertility. Furthermore, mutations in the PLCζ gene and abnormalities in sperm PLCζ protein and RNA, have been strongly associated with forms of male infertility where oocyte activation is deficient. Concurrently, specific patterns and profiles of PLCζ in human sperm have been linked to parameters of semen quality, suggesting the potential for PLCζ as a powerful target for both therapeutics and diagnostics of human fertility. However, further to PLCζ and given the strong role played by Ca2+ in fertilisation, targets down- and up-stream of this process may also present a significantly similar level of promise. Herein, we systematically summarise recent advancements and controversies in the field to update expanding clinical associations between Ca2+-release, PLCζ, oocyte activation and human fertility. We discuss how such associations may potentially underlie defective embryogenesis and recurrent implantation failure following fertility treatments, alongside potential diagnostic and therapeutic avenues presented by oocyte activation for the diagnosis and treatment of human infertility.
Collapse
|
4
|
The Effect of Acidic and Alkaline Seawater on the F-Actin-Dependent Ca 2+ Signals Following Insemination of Immature Starfish Oocytes and Mature Eggs. Cells 2023; 12:cells12050740. [PMID: 36899875 PMCID: PMC10000582 DOI: 10.3390/cells12050740] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/07/2023] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
In starfish, the addition of the hormone 1-methyladenine (1-MA) to immature oocytes (germinal vesicle, GV-stage) arrested at the prophase of the first meiotic division induces meiosis resumption (maturation), which makes the mature eggs able to respond to the sperm with a normal fertilization response. The optimal fertilizability achieved during the maturation process results from the exquisite structural reorganization of the actin cytoskeleton in the cortex and cytoplasm induced by the maturing hormone. In this report, we have investigated the influence of acidic and alkaline seawater on the structure of the cortical F-actin network of immature oocytes of the starfish (Astropecten aranciacus) and its dynamic changes upon insemination. The results have shown that the altered seawater pH strongly affected the sperm-induced Ca2+ response and the polyspermy rate. When immature starfish oocytes were stimulated with 1-MA in acidic or alkaline seawater, the maturation process displayed a strong dependency on pH in terms of the dynamic structural changes of the cortical F-actin. The resulting alteration of the actin cytoskeleton, in turn, affected the pattern of Ca2+ signals at fertilization and sperm penetration.
Collapse
|
5
|
Santella L, Chun JT. Structural actin dynamics during oocyte maturation and fertilization. Biochem Biophys Res Commun 2022; 633:13-16. [DOI: 10.1016/j.bbrc.2022.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/06/2022]
|
6
|
Regulation of the Actin Cytoskeleton-Linked Ca2+ Signaling by Intracellular pH in Fertilized Eggs of Sea Urchin. Cells 2022; 11:cells11091496. [PMID: 35563801 PMCID: PMC9100012 DOI: 10.3390/cells11091496] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/19/2022] [Accepted: 04/26/2022] [Indexed: 01/27/2023] Open
Abstract
In sea urchin, the immediate contact of the acrosome-reacted sperm with the egg surface triggers a series of structural and ionic changes in the egg cortex. Within one minute after sperm fuses with the egg plasma membrane, the cell membrane potential changes with the concurrent increases in intracellular Ca2+ levels. The consequent exocytosis of the cortical granules induces separation of the vitelline layer from the egg plasma membrane. While these cortical changes are presumed to prevent the fusion of additional sperm, the subsequent late phase (between 1 and 4 min after fertilization) is characterized by reorganization of the egg cortex and microvilli (elongation) and by the metabolic shift to activate de novo protein and DNA syntheses. The latter biosynthetic events are crucial for embryonic development. Previous studies suggested that the early phase of fertilization was not a prerequisite for these changes in the second phase since the increase in the intracellular pH induced by the exposure of unfertilized sea urchin eggs to ammonia seawater could start metabolic egg activation in the absence of the cortical granule exocytosis. In the present study, we have demonstrated that the incubation of unfertilized eggs in ammonia seawater induced considerable elongations of microvilli (containing actin filaments) as a consequence of the intracellular pH increase, which increased the egg’s receptivity to sperm and made the eggs polyspermic at fertilization despite the elevation of the fertilization envelope (FE). These eggs also displayed compromised Ca2+ signals at fertilization, as the amplitude of the cortical flash was significantly reduced and the elevated intracellular Ca2+ level declined much faster. These results have also highlighted the importance of the increased internal pH in regulating Ca2+ signaling and the microvillar actin cytoskeleton during the late phase of the fertilization process.
Collapse
|
7
|
Vasilev F, Ezhova Y, Chun JT. Signaling Enzymes and Ion Channels Being Modulated by the Actin Cytoskeleton at the Plasma Membrane. Int J Mol Sci 2021; 22:ijms221910366. [PMID: 34638705 PMCID: PMC8508623 DOI: 10.3390/ijms221910366] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 02/06/2023] Open
Abstract
A cell should deal with the changing external environment or the neighboring cells. Inevitably, the cell surface receives and transduces a number of signals to produce apt responses. Typically, cell surface receptors are activated, and during this process, the subplasmalemmal actin cytoskeleton is often rearranged. An intriguing point is that some signaling enzymes and ion channels are physically associated with the actin cytoskeleton, raising the possibility that the subtle changes of the local actin cytoskeleton can, in turn, modulate the activities of these proteins. In this study, we reviewed the early and new experimental evidence supporting the notion of actin-regulated enzyme and ion channel activities in various cell types including the cells of immune response, neurons, oocytes, hepatocytes, and epithelial cells, with a special emphasis on the Ca2+ signaling pathway that depends on the synthesis of inositol 1,4,5-trisphosphate. Some of the features that are commonly found in diverse cells from a wide spectrum of the animal species suggest that fine-tuning of the activities of the enzymes and ion channels by the actin cytoskeleton may be an important strategy to inhibit or enhance the function of these signaling proteins.
Collapse
Affiliation(s)
- Filip Vasilev
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), 900 Rue St Denis, Montreal, QC H2X 0A9, Canada
- Correspondence: (F.V.); (J.T.C.); Tel.: +1-514-249-5862 (F.V.); +39-081-583-3407 (J.T.C.)
| | - Yulia Ezhova
- Maisonneuve-Rosemont Hospital Research Centre, University of Montreal, Montreal, QC H1T 2M4, Canada;
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
- Correspondence: (F.V.); (J.T.C.); Tel.: +1-514-249-5862 (F.V.); +39-081-583-3407 (J.T.C.)
| |
Collapse
|
8
|
Limatola N, Chun JT, Santella L. Fertilization and development of Arbacia lixula eggs are affected by osmolality conditions. Biosystems 2021; 206:104448. [PMID: 34058296 DOI: 10.1016/j.biosystems.2021.104448] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 05/21/2021] [Accepted: 05/21/2021] [Indexed: 10/21/2022]
Abstract
The sea urchin Arbacia lixula coexist with Paracentrotus lividus in the Mediterranean, but the two sea urchin species are quite different from each other. Concerning the female gamete, A. lixula eggs are much darker than those of P. lividus due to the characteristic pigmentation. Upon insemination, the fertilization envelope formed by A. lixula eggs is remarkably thinner than that of P. livius eggs, which implies that the cortical organization of the eggs in the two species may be quite different. In this communication, we examined the phenotypic plasticity of A. lixula eggs in the changing osmolality. The plasma membrane, cortical actin cytoskeleton and vesicles are extensively altered in the eggs exposed to 40% seawater for 15 min. When fertilized, the Ca2+ response in these eggs was significantly compromised and the sperm often failed to enter the eggs. Remarkably, the pattern of the Ca2+ response was restored when these eggs were transferring back to the natural seawater before fertilization, while the actin cytoskeleton partially reverted to the original state. Nonetheless, these eggs restored in seawater failed to regain the innate sperm receptivity that allows only one sperm to enter in natural seawater. Thus, the ability to guide monospermic fertilization is lost by water entry into the eggs, and the eggs incorporated either multiple or no sperm. On the other hand, eggs briefly exposed to hypertonic seawater exhibited no evident morphological anomaly. Nonetheless, the monospermic eggs that experienced a brief exposure (15 min) to hypertonic seawater prior to fertilization in natural seawater displayed a subtly altered sperm-induced Ca2+ response and morpho-functional anomaly around the pluteus stage. Our results suggest that A. lixula eggs attain only a limited extent of cytological plasticity, and that the osmolality shock affects the physical nature of the egg surface which in turn affects the developmental programming.
Collapse
Affiliation(s)
- Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy.
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy
| |
Collapse
|
9
|
Limatola N, Chun JT, Santella L. Effects of Salinity and pH of Seawater on the Reproduction of the Sea Urchin Paracentrotus lividus. THE BIOLOGICAL BULLETIN 2020; 239:13-23. [PMID: 32812816 DOI: 10.1086/710126] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
AbstractFertilization and early development are usually the most vulnerable stages in the life of marine animals, and the biological processes during this period are highly sensitive to the environment. In nature, sea urchin gametes are shed in seawater, where they undergo external fertilization and embryonic development. In a laboratory, it is possible to follow the exact morphological and biochemical changes taking place in the fertilized eggs and the developing embryos. Thus, observation of successful fertilization and the subsequent embryonic development of sea urchin eggs can be used as a convenient biosensor to assess the quality of the marine environment. In this paper, we have examined how salinity and pH changes affect the normal fertilization process and the following development of Paracentrotus lividus. The results of our studies using confocal microscopy, scanning and transmission electron microscopy, and time-lapse Ca2+ image recording indicated that both dilution and acidification of seawater have subtle but detrimental effects on many aspects of the fertilization process. They include Ca2+ signaling and coordinated actin cytoskeletal changes, leading to a significantly reduced rate of successful fertilization and, eventually, to abnormal or delayed embryonic development.
Collapse
|
10
|
Santella L, Limatola N, Chun JT. Cellular and molecular aspects of oocyte maturation and fertilization: a perspective from the actin cytoskeleton. ZOOLOGICAL LETTERS 2020; 6:5. [PMID: 32313685 PMCID: PMC7158055 DOI: 10.1186/s40851-020-00157-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/26/2020] [Indexed: 05/06/2023]
Abstract
ABSTRACT Much of the scientific knowledge on oocyte maturation, fertilization, and embryonic development has come from the experiments using gametes of marine organisms that reproduce by external fertilization. In particular, echinoderm eggs have enabled the study of structural and biochemical changes related to meiotic maturation and fertilization owing to the abundant availability of large and transparent oocytes and eggs. Thus, in vitro studies of oocyte maturation and sperm-induced egg activation in starfish are carried out under experimental conditions that resemble those occurring in nature. During the maturation process, immature oocytes of starfish are released from the prophase of the first meiotic division, and acquire the competence to be fertilized through a highly programmed sequence of morphological and physiological changes at the oocyte surface. In addition, the changes in the cortical and nuclear regions are essential for normal and monospermic fertilization. This review summarizes the current state of research on the cortical actin cytoskeleton in mediating structural and physiological changes during oocyte maturation and sperm and egg activation in starfish and sea urchin. The common denominator in these studies with echinoderms is that exquisite rearrangements of the egg cortical actin filaments play pivotal roles in gamete interactions, Ca2+ signaling, exocytosis of cortical granules, and control of monospermic fertilization. In this review, we also compare findings from studies using invertebrate eggs with what is known about the contributions made by the actin cytoskeleton in mammalian eggs. Since the cortical actin cytoskeleton affects microvillar morphology, movement, and positioning of organelles and vesicles, and the topography of the egg surface, these changes have impacts on the fertilization process, as has been suggested by recent morphological studies on starfish oocytes and eggs using scanning electron microscopy. Drawing the parallelism between vitelline layer of echinoderm eggs and the zona pellucida of mammalian eggs, we also discuss the importance of the egg surface in mediating monospermic fertilization. GRAPHICAL ABSTRACT
Collapse
Affiliation(s)
- Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| | - Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| |
Collapse
|
11
|
Nicotine Induces Polyspermy in Sea Urchin Eggs through a Non-Cholinergic Pathway Modulating Actin Dynamics. Cells 2019; 9:cells9010063. [PMID: 31881774 PMCID: PMC7016604 DOI: 10.3390/cells9010063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/02/2019] [Accepted: 12/21/2019] [Indexed: 01/02/2023] Open
Abstract
While alkaloids often exert unique pharmacological effects on animal cells, exposure of sea urchin eggs to nicotine causes polyspermy at fertilization in a dose-dependent manner. Here, we studied molecular mechanisms underlying the phenomenon. Although nicotine is an agonist of ionotropic acetylcholine receptors, we found that nicotine-induced polyspermy was neither mimicked by acetylcholine and carbachol nor inhibited by specific antagonists of nicotinic acetylcholine receptors. Unlike acetylcholine and carbachol, nicotine uniquely induced drastic rearrangement of egg cortical microfilaments in a dose-dependent way. Such cytoskeletal changes appeared to render the eggs more receptive to sperm, as judged by the significant alleviation of polyspermy by latrunculin-A and mycalolide-B. In addition, our fluorimetric assay provided the first evidence that nicotine directly accelerates polymerization kinetics of G-actin and attenuates depolymerization of preassembled F-actin. Furthermore, nicotine inhibited cofilin-induced disassembly of F-actin. Unexpectedly, our results suggest that effects of nicotine can also be mediated in some non-cholinergic pathways.
Collapse
|
12
|
Ebrahimdamavandi S, Mobasheri H. Application of a static magnetic field as a complementary aid to healing in an in vitro wound model. J Wound Care 2019; 28:40-52. [PMID: 30625046 DOI: 10.12968/jowc.2019.28.1.40] [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] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Static magnetic field (SMF) has long been used as a therapeutic means, though its effects on the activity of cells and the mechanism(s) involved remain unknown. The purpose of this study is to determine the effect of a moderate-intensity SMF on the activity, growth and migration of mouse embryonic fibroblast (NIH 3T3), aiming to mimic wound healing and to study it in real time. METHOD A cell-free area (a scratch with a 200-500µm width) was formed in NIH 3T3 cultured cells and used as a wound model. The effects of a SMF (10, 50, 80 and 100mT) on the survival rate (MTT assay), integrity of cell membranes (lactate dehydrogenase (LDH) assay), the morphology of the cell (circularity, number and length of filopodia), cell orientation, and migration (speed, direction, rate) were studied as a function of the incubation time in a time-lapse manner. RESULTS The exposure of cells to SMF at all intensities had no cytotoxic effect, as revealed by the MTT assay. The integrity of the membranes of the SMF-treated cells studied by the LDH assay test showed no effects. The structure of the membrane at the leading edge of the cells changed and showed several filopodia extended parallel to the field direction. The exposure to the SMF elongated the cells and decreased their circularity at SMF 10mT. The migration of the cells from one edge of the gap towards the other was affected by the applied SMF. The maximum and minimum effects were monitored at 80mT and 10mT, respectively. Analysis of cell migration revealed an average directness of 0.73, 0.66, 0.78, 0.78 and 0.69 under SMF 10, 50, 80, 100mT and control, respectively. CONCLUSION The morphological and functional changes of the cells in the presence of SMF revealed particular effects on the membrane and cytoskeleton. Cells were affected by physicochemical changes caused by the applied SMF, though the extent of the incurred effects was not a linear function of the field intensity. This low cost, non-invasive approach can be used as a magneto-manipulative means to tailor a practical, independent or complementary means of manipulating the activities of cells and tissues for clinical purposes.
Collapse
Affiliation(s)
- Sajedeh Ebrahimdamavandi
- PhD student, Laboratory of Membrane Biophysics and Macromolecules. Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Hamid Mobasheri
- Professor of Biophysics, Head of Laboratory, Laboratory of Membrane Biophysics and Macromolecules. Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Biomaterials Research Center (BRC), University of Tehran and Tehran University of Medical Sciences, Tehran, Iran
| |
Collapse
|
13
|
Vasilev F, Limatola N, Chun JT, Santella L. Contributions of suboolemmal acidic vesicles and microvilli to the intracellular Ca 2+ increase in the sea urchin eggs at fertilization. Int J Biol Sci 2019; 15:757-775. [PMID: 30906208 PMCID: PMC6429021 DOI: 10.7150/ijbs.28461] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/15/2018] [Indexed: 12/03/2022] Open
Abstract
The onset of fertilization in echinoderms is characterized by instantaneous increase of Ca2+ in the egg cortex, which is called 'cortical flash', and the subsequent Ca2+ wave. While the cortical flash is due to the ion influx through L-type Ca2+ channels in starfish eggs, its amplitude was shown to be affected by the integrity of the egg cortex. Here, we investigated the contribution of cortical granules (CG) and yolk granules (YG) to the sperm-induced Ca2+ signals in sea urchin eggs. To this end, prior to fertilization, Paracentrotus lividus eggs were treated with agents that disrupt or relocate CG beneath the plasma membrane: namely, glycyl-L-phenylalanine 2-naphthylamide (GPN), procaine, urethane, and NH4Cl. All these pretreatments consistently suppressed the cortical flash in the fertilized eggs, and accelerated the decay kinetics of the subsiding Ca2+ wave in most cases. By contrast, centrifugation of the eggs, which stratifies organelles but not the CG, did not exhibit such changes except that the CF was much enhanced in the centrifugal pole where YG are localized. Surprisingly, we noted that pretreatment of the eggs with these CG-disrupting agents or with the inhibitors of L-type Ca2+ channels all drastically reduced the density of the microvilli and their individual shapes on the egg surface. Taken together, our results suggest that the integrity of the egg cortex ensures successful generation of the Ca2+ responses at fertilization, and that modulation of microvilli shape and density may serve as a mechanism of controlling ion flux across the plasma membrane.
Collapse
Affiliation(s)
- F Vasilev
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - N Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - J T Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - L Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy
| |
Collapse
|
14
|
Maturation and fertilization of echinoderm eggs: Role of actin cytoskeleton dynamics. Biochem Biophys Res Commun 2018; 506:361-371. [DOI: 10.1016/j.bbrc.2018.09.084] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 01/31/2023]
|
15
|
Chun JT, Vasilev F, Limatola N, Santella L. Fertilization in Starfish and Sea Urchin: Roles of Actin. Results Probl Cell Differ 2018; 65:33-47. [PMID: 30083914 DOI: 10.1007/978-3-319-92486-1_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Marine animals relying on "external fertilization" provide advantageous opportunities to study the mechanisms of gamete activation and fusion, as well as the subsequent embryonic development. Owing to the large number of eggs that are easily available and handled, starfish and sea urchins have been chosen as favorable animal models in this line of research for over 150 years. Indeed, much of our knowledge on fertilization came from studies in the echinoderms. Fertilization involves mutual stimulation between eggs and sperm, which leads to morphological, biochemical, and physiological changes on both sides to ensure successful gamete fusion. In this chapter, we review the roles of actin in the fertilization of starfish and sea urchin eggs. As fertilization is essentially an event that takes place on the egg surface, it has been predicted that suboolemmal actin filaments would make significant contributions to sperm entry. A growing body of evidence from starfish and sea urchin eggs suggests that the prompt reorganization of the actin pools around the time of fertilization plays crucial regulatory roles not only in guiding sperm entry but also in modulating intracellular Ca2+ signaling and egg activation.
Collapse
Affiliation(s)
- Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy.
| | - Filip Vasilev
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Nunzia Limatola
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Luigia Santella
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy.
| |
Collapse
|
16
|
Development of Ca2+-release mechanisms during oocyte maturation of the starfish Asterina pectinifera. ZYGOTE 2016; 24:857-868. [PMID: 27692029 DOI: 10.1017/s0967199416000186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An important step for successful fertilization and further development is the increase in intracellular Ca2+ in the activated oocyte. It has been known that starfish oocytes become increasingly sensitive to inositol 1,4,5-trisphosphate (IP3) during meiotic maturation to exhibit highly efficient IP3-induced Ca2+ release (IICR) by the time of germinal vesicle breakdown (GVBD). However, we noted that the peak level of intracellular Ca2+ increase after insemination is already high in the maturing oocytes before GVBD. Using maturing oocytes before GVBD, we investigated Ca2+ release mechanisms other than IICR. We report here that Ca2+-release mechanisms dependent on nicotinic acid adenine dinucleotide phosphate (NAADP) and nicotinamide adenine dinucleotide (NADP), the precursor of NAADP, became functional prior to the development of IICR mechanisms. As with IP3, but unlike NAADP, the Ca2+ stores responsive to NADP are sensitized during the meiotic maturation induced by 1-methyladenine (1-MA). This suggests that the process may represent a physiological response to the maturation hormone. NADP-dependent Ca2+ release in immature oocytes, however, did not induce oocyte maturation by itself, but was enhanced by the conditions mimicking the increases of intracellular Ca2+ and pH that take place in the maturing oocytes of starfish.
Collapse
|
17
|
Santella L, Limatola N, Chun JT. Calcium and actin in the saga of awakening oocytes. Biochem Biophys Res Commun 2015; 460:104-13. [PMID: 25998739 DOI: 10.1016/j.bbrc.2015.03.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/06/2015] [Indexed: 12/12/2022]
Abstract
The interaction of the spermatozoon with the egg at fertilization remains one of the most fascinating mysteries of life. Much of our scientific knowledge on fertilization comes from studies on sea urchin and starfish, which provide plenty of gametes. Large and transparent, these eggs have served as excellent model systems for studying egg activation and embryo development in seawater, a plain natural medium. Starfish oocytes allow the study of the cortical, cytoplasmic and nuclear changes during the meiotic maturation process, which can also be triggered in vitro by hormonal stimulation. These morphological and biochemical changes ensure successful fertilization of the eggs at the first metaphase. On the other hand, sea urchin eggs are fertilized after the completion of meiosis, and are particularly suitable for the study of sperm-egg interaction, early events of egg activation, and embryonic development, as a large number of mature eggs can be fertilized synchronously. Starfish and sea urchin eggs undergo abrupt changes in the cytoskeleton and ion fluxes in response to the fertilizing spermatozoon. The plasma membrane and cortex of an egg thus represent "excitable media" that quickly respond to the stimulus with the Ca(2+) swings and structural changes. In this article, we review some of the key findings on the rapid dynamic rearrangements of the actin cytoskeleton in the oocyte/egg cortex upon hormonal or sperm stimulation and their roles in the modulation of the Ca(2+) signals and in the control of monospermic fertilization.
Collapse
Affiliation(s)
- Luigia Santella
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli, I-80121, Italy.
| | - Nunzia Limatola
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli, I-80121, Italy
| | - Jong T Chun
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli, I-80121, Italy
| |
Collapse
|
18
|
Chun JT, Limatola N, Vasilev F, Santella L. Early events of fertilization in sea urchin eggs are sensitive to actin-binding organic molecules. Biochem Biophys Res Commun 2014; 450:1166-74. [DOI: 10.1016/j.bbrc.2014.06.057] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/11/2014] [Indexed: 10/25/2022]
|
19
|
Nakano T, Deguchi R, Kyozuka K. Intracellular calcium signaling in the fertilized eggs of Annelida. Biochem Biophys Res Commun 2014; 450:1188-94. [PMID: 24953697 DOI: 10.1016/j.bbrc.2014.06.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/11/2014] [Indexed: 11/19/2022]
Abstract
Fertilization is such a universal and indispensable step in sexual reproduction, but a high degree of variability exists in the way it takes place in the animal kingdom. As discussed in other reviews in this issue, recent works on this subject clarified many points. However, important results on the mechanisms of fertilization are obtained mainly from a few restricted model organisms. In this sense, it is utterly important to collect more information from various phyla. In this review, we have re-introduced Annelida as one of the most suitable models for the analysis of fertilization process. We have briefly reviewed the historical works on the fertilization of Annelida. Then, we have described recent findings on the two independent Ca(2+) increases in the fertilized eggs of Annelida, which arise from two different mechanisms and may have distinct physiological roles toward sperm entry and egg activation. We propose that the Ca(2+) increase in the fertilized eggs reflect the specific needs of the zygote in a given species.
Collapse
Affiliation(s)
- Takeshi Nakano
- Research Center for Marine Biology, Asamushi, Graduate School of Life Science, Tohoku University Asamushi, Aomori 039-3501, Japan.
| | - Ryusaku Deguchi
- Department of Biology, Miyagi University of Education, Sendai, Miyagi 980-0845, Japan.
| | - Keiichiro Kyozuka
- Research Center for Marine Biology, Asamushi, Graduate School of Life Science, Tohoku University Asamushi, Aomori 039-3501, Japan.
| |
Collapse
|
20
|
Vandrangi P, Lo DD, Kozaka R, Ozaki N, Carvajal N, Rodgers VGJ. Electrostatic properties of confluent Caco-2 cell layer correlates to their microvilli growth and determines underlying transcellular flow. Biotechnol Bioeng 2013; 110:2742-8. [PMID: 23613195 DOI: 10.1002/bit.24939] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/07/2013] [Accepted: 04/11/2013] [Indexed: 01/10/2023]
Abstract
Recently, Rajapaksa et al. (2010) showed that the rate of uptake of potential vaccine delivery nanoparticles in the mucosal layer is a function of the electrostatic properties of the corresponding solvent. This fundamentally implies that the dominant driving forces that may be capitalized on for mucosal vaccine strategies are electrostatic in nature. We hypothesize that the driving force normal to the cell (in the direction from apical to basolateral across the cell) is of particular importance. In addition, it has been theoretically shown that the electrostatic properties of mucosal cells are directly related to their development of brush border. Here we correlate the development of brush border on a human mucosal epithelial model (Caco-2) cultured in DMEM on 3.0 µm pore sized polycarbonate membranes to their corresponding electrostatic properties characterized by measuring their normal zeta potential. Properties of normal streaming potential, hydraulic permeability, and brush border development (as determined by size and number) were monitored for 2, 6, and 16 days (after cells were confluent). Human endothelial cells (HECs), which lack brush border, were used as the control. Our results demonstrate that normal zeta potential of Caco-2 cells significantly changed from -5.7 ± 0.11 mV to -3.4 ± 0.11 mV for a period between 2 and 16 days, respectively. The zeta potential of the control cell line, HECs, stayed constant (statistically not different, P > 0.05) for the duration of the experiments. Our results show that the calculated increase in surface area of the Caco-2 cells with microvilli from 6 to 16 days was directly proportional to the corresponding measured zeta potential difference. These results imply that microvilli alter the electrostatic local environment around Caco-2 cells and, hence, enhance the normal electrostatic selective transport of solute across the mucosal barrier.
Collapse
Affiliation(s)
- P Vandrangi
- Department of Bioengineering, University of California, Riverside, California 92521, USA
| | | | | | | | | | | |
Collapse
|
21
|
Markova O, Lenne PF. Calcium signaling in developing embryos: focus on the regulation of cell shape changes and collective movements. Semin Cell Dev Biol 2012; 23:298-307. [PMID: 22414534 DOI: 10.1016/j.semcdb.2012.03.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 01/31/2012] [Accepted: 03/04/2012] [Indexed: 10/28/2022]
Abstract
During morphogenesis tissues significantly remodel by coordinated cell migrations and cell rearrangements. Central to this problem are cell shape changes that are driven by distinct cytoskeletal reorganization responsible for force generation. Calcium is a versatile and universal messenger that is implicated in the regulation of embryonic development. Although calcium transients accrue clearly and more intensely in tissues undergoing rearrangement/migration, it is far from clear what the role of these calcium signals is. Here we summarize the evidence implicating calcium participation in tissue movements, cell shape changes and the reorganization of contractile cytoskeletal elements in developing embryos. We also discuss a novel hypothesis that short-lived calcium spikes are required in cells and tissues undergoing migration and rearrangements as a fine tuning response mechanism to prevent local, abnormally high fluctuations in cytoskeletal activities.
Collapse
Affiliation(s)
- Olga Markova
- IBDML, UMR7288 CNRS-Aix-Marseille Université, Campus de Luminy, Marseille, France.
| | | |
Collapse
|
22
|
Actin, more than just a housekeeping protein at the scene of fertilization. SCIENCE CHINA-LIFE SCIENCES 2011; 54:733-43. [DOI: 10.1007/s11427-011-4202-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 06/20/2011] [Indexed: 10/18/2022]
|
23
|
Abstract
It is becoming evident that failure in the removal of dying cells causes and/or promotes the onset of chronic diseases. Impairment of phagocytosis of apoptotic cells can be due not only to genetic or molecular malfunctioning but also to external/environmental factors. Two of these environmental factors have been recently reported to down regulate the clearance of apoptotic cells: cigarette smoke and static magnetic fields. Cigarette smoke contains highly reactive carbonyls that modify proteins which directly/indirectly affects cellular function. Human macrophages interacting with carbonyl or cigarette smoke modified extracellular matrix (ECM) proteins dramatically down regulated their ability to phagocytose apoptotic neutrophils. It was postulated that changes in the ECM environment as a result of cigarette smoke affect the ability of macrophages to remove apoptotic cells. This decreased phagocytic activity was as a result of sequestration of receptors involved in the uptake of apoptotic cells towards that of recognition of carbonyl adducts on the modified ECM proteins leading to increased macrophage adhesion. Downregulation of the phagocytosis of apoptotic cells was also described when performed in presence of static magnetic fields (SMFs) of moderate intensity. SMFs have been reported to perturb distribution of membrane proteins and glycoproteins, receptors, cytoskeleton and trans-membrane fluxes of different ions, especially calcium [Ca(2+)]i, that in turn, interfere with many different physiological activities, including phagocytosis. The effects of cigarette smoke and SMF on the phagocytosis of dying cells will be here discussed.
Collapse
Affiliation(s)
- Luciana Dini
- Department Biological and Environmental Science and Technology, University of the Salento, Lecce, Italy.
| |
Collapse
|
24
|
Lange K. Fundamental role of microvilli in the main functions of differentiated cells: Outline of an universal regulating and signaling system at the cell periphery. J Cell Physiol 2010; 226:896-927. [PMID: 20607764 DOI: 10.1002/jcp.22302] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
25
|
Myosin motor function: the ins and outs of actin-based membrane protrusions. Cell Mol Life Sci 2010; 67:1239-54. [PMID: 20107861 DOI: 10.1007/s00018-009-0254-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2009] [Revised: 12/15/2009] [Accepted: 12/28/2009] [Indexed: 10/19/2022]
Abstract
Cells build plasma membrane protrusions supported by parallel bundles of F-actin to enable a wide variety of biological functions, ranging from motility to host defense. Filopodia, microvilli and stereocilia are three such protrusions that have been the focus of intense biological and biophysical investigation in recent years. While it is evident that actin dynamics play a significant role in the formation of these organelles, members of the myosin superfamily have also been implicated as key players in the maintenance of protrusion architecture and function. Based on a simple analysis of the physical forces that control protrusion formation and morphology, as well as our review of available data, we propose that myosins play two general roles within these structures: (1) as cargo transporters to move critical regulatory components toward distal tips and (2) as mediators of membrane-cytoskeleton adhesion.
Collapse
|
26
|
Calcium-actin waves and oscillations of cellular membranes. Biophys J 2009; 97:1558-68. [PMID: 19751660 DOI: 10.1016/j.bpj.2009.07.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Revised: 06/18/2009] [Accepted: 07/01/2009] [Indexed: 01/16/2023] Open
Abstract
We propose a mechanism for the formation of membrane oscillations and traveling waves, which arise due to the coupling between the actin cytoskeleton and the calcium flux through the membrane. In our model, the fluid cell membrane has a mobile but constant population of proteins with a convex spontaneous curvature, which act as nucleators of actin polymerization and adhesion. Such a continuum model couples the forces of cell-substrate adhesion, actin polymerization, membrane curvature, and the flux of calcium through the membrane. Linear stability analysis shows that sufficiently strong coupling among the calcium, membrane, and protein dynamics may induce robust traveling waves on the membrane. This result was checked for a reduced feedback scheme and is compared to the results without the effects of calcium, where permanent phase separation without waves or oscillations is obtained. The model results are compared to the published observations of calcium waves in cell membranes, and a number of testable predictions are proposed.
Collapse
|
27
|
Dini L, Dwikat M, Panzarini E, Vergallo C, Tenuzzo B. Morphofunctional study of 12-O-tetradecanoyl-13-phorbol acetate (TPA)-induced differentiation of U937 cells under exposure to a 6 mT static magnetic field. Bioelectromagnetics 2009; 30:352-64. [PMID: 19189300 DOI: 10.1002/bem.20474] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Luciana Dini
- Department of Biological and Environmental Science and Technology (Disteba), University of Salento, Via per Monteroni, Lecce, Italy.
| | | | | | | | | |
Collapse
|
28
|
Chun JT, Santella L. The actin cytoskeleton in meiotic maturation and fertilization of starfish eggs. Biochem Biophys Res Commun 2009; 384:141-3. [DOI: 10.1016/j.bbrc.2009.04.087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 04/19/2009] [Indexed: 10/20/2022]
|
29
|
Rosen AD, Chastney EE. Effect of long term exposure to 0.5 T static magnetic fields on growth and size of GH3 cells. Bioelectromagnetics 2009; 30:114-9. [PMID: 18839411 DOI: 10.1002/bem.20452] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Arthur D Rosen
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana.
| | | |
Collapse
|
30
|
Abstract
Starfish oocytes undergo massive intracellular Ca2+ signalling during meiotic maturation and fertilization. Although the igniting stimulus of Ca2+ mobilization may differ in different cell contexts, its final leverage is usually the Ca2+-releasing second messengers such as InsP3, cADPr and NAADP. The general scheme of intracellular Ca2+ release is that the corresponding receptors for these molecules serve as ion channels to release free Ca2+ from its internal stores such as the lumen of the endoplasmic reticulum. However, a growing body of evidence has suggested that intracellular Ca2+ release can be strongly modulated by the actin cytoskeleton. Although it is known that Ca2+ contributes to remodelling of the actin cytoskeleton, whether the actin cytoskeleton modulates Ca2+ signalling in return has not been much explored. An emerging candidate to answer to this reciprocal causality of Ca2+ and the actin cytoskeleton may be actin-binding proteins. In this review, we discuss how the actin cytoskeleton may fit into the known mechanisms of intracellular Ca2+ release, and propose two models to explain the experimental data.
Collapse
Affiliation(s)
- J T Chun
- Stazione Zoologica Anton Dohrn, Napoli, Italy
| | | |
Collapse
|
31
|
Pritchard S, Votta BJ, Kumar S, Guilak F. Interleukin-1 inhibits osmotically induced calcium signaling and volume regulation in articular chondrocytes. Osteoarthritis Cartilage 2008; 16:1466-73. [PMID: 18495501 PMCID: PMC3217044 DOI: 10.1016/j.joca.2008.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 04/04/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Articular chondrocytes respond to osmotic stress with transient changes in cell volume and the intracellular concentration of calcium ion ([Ca(2+)](i)). The goal of this study was to examine the hypothesis that interleukin-1 (IL-1), a pro-inflammatory cytokine associated with osteoarthritis, influences osmotically induced Ca(2+) signaling. METHODS Fluorescence ratio imaging was used to measure [Ca(2+)](i) and cell volume in response to hypo- or hyper-osmotic stress in isolated porcine chondrocytes, with or without pre-exposure to 10-ng/ml IL-1alpha. Inhibitors of IL-1 (IL-1 receptor antagonist, IL-1Ra), Ca(2+) mobilization (thapsigargin, an inhibitor of Ca-ATPases), and cytoskeletal remodeling (toxin B, an inhibitor of the Rho family of small GTPases) were used to determine the mechanisms involved in increased [Ca(2+)](i), F-actin remodeling, volume adaptation and active volume recovery. RESULTS In response to osmotic stress, chondrocytes exhibited transient increases in [Ca(2+)](i), generally followed by decaying oscillations. Pre-exposure to IL-1 significantly inhibited regulatory volume decrease (RVD) following hypo-osmotic swelling and reduced the change in cell volume and the time to peak [Ca(2+)](i) in response to hyper-osmotic stress, but did not affect the peak magnitudes of [Ca(2+)](i) in those cells that did respond. Co-treatment with IL-1Ra, thapsigargin, or toxin B restored these responses to control levels. The effects were associated with alterations in F-actin organization. CONCLUSIONS IL-1 alters the normal volumetric and Ca(2+) signaling response of chondrocytes to osmotic stress through mechanisms involving F-actin remodeling via small Rho GTPases. These findings provide further insights into the mechanisms by which IL-1 may interfere with normal physiologic processes in the chondrocyte, such as the adaptation or regulatory responses to mechanical or osmotic loading.
Collapse
Affiliation(s)
- Scott Pritchard
- Department of Surgery, Duke University Medical Center Durham, North Carolina, 27710 USA,Department of Biomedical Engineering, Duke University Medical Center Durham, North Carolina, 27710 USA
| | - Bartholomew J. Votta
- Department of Musculoskeletal Disease GlaxoSmithKline, Inc. 1250 S. Collegeville Rd, P.O. Box 5089 Collegeville, PA 19426-0989 USA
| | - Sanjay Kumar
- Department of Musculoskeletal Disease GlaxoSmithKline, Inc. 1250 S. Collegeville Rd, P.O. Box 5089 Collegeville, PA 19426-0989 USA
| | - Farshid Guilak
- Department of Surgery, Duke University Medical Center Durham, North Carolina, 27710 USA,Department of Biomedical Engineering, Duke University Medical Center Durham, North Carolina, 27710 USA
| |
Collapse
|
32
|
Puppo A, Chun JT, Gragnaniello G, Garante E, Santella L. Alteration of the cortical actin cytoskeleton deregulates Ca2+ signaling, monospermic fertilization, and sperm entry. PLoS One 2008; 3:e3588. [PMID: 18974786 PMCID: PMC2570615 DOI: 10.1371/journal.pone.0003588] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 10/10/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND When preparing for fertilization, oocytes undergo meiotic maturation during which structural changes occur in the endoplasmic reticulum (ER) that lead to a more efficient calcium response. During meiotic maturation and subsequent fertilization, the actin cytoskeleton also undergoes dramatic restructuring. We have recently observed that rearrangements of the actin cytoskeleton induced by actin-depolymerizing agents, or by actin-binding proteins, strongly modulate intracellular calcium (Ca2+) signals during the maturation process. However, the significance of the dynamic changes in F-actin within the fertilized egg has been largely unclear. METHODOLOGY/PRINCIPAL FINDINGS We have measured changes in intracellular Ca2+ signals and F-actin structures during fertilization. We also report the unexpected observation that the conventional antagonist of the InsP(3) receptor, heparin, hyperpolymerizes the cortical actin cytoskeleton in postmeiotic eggs. Using heparin and other pharmacological agents that either hypo- or hyperpolymerize the cortical actin, we demonstrate that nearly all aspects of the fertilization process are profoundly affected by the dynamic restructuring of the egg cortical actin cytoskeleton. CONCLUSIONS/SIGNIFICANCE Our findings identify important roles for subplasmalemmal actin fibers in the process of sperm-egg interaction and in the subsequent events related to fertilization: the generation of Ca2+ signals, sperm penetration, cortical granule exocytosis, and the block to polyspermy.
Collapse
Affiliation(s)
- A. Puppo
- Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | - Jong T. Chun
- Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | | | - Ezio Garante
- Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | - Luigia Santella
- Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| |
Collapse
|
33
|
Kyozuka K, Chun JT, Puppo A, Gragnaniello G, Garante E, Santella L. Actin cytoskeleton modulates calcium signaling during maturation of starfish oocytes. Dev Biol 2008; 320:426-35. [DOI: 10.1016/j.ydbio.2008.05.549] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 05/23/2008] [Accepted: 05/27/2008] [Indexed: 10/22/2022]
|
34
|
Elsaesser R, Paysan J. The sense of smell, its signalling pathways, and the dichotomy of cilia and microvilli in olfactory sensory cells. BMC Neurosci 2007; 8 Suppl 3:S1. [PMID: 17903277 PMCID: PMC1995455 DOI: 10.1186/1471-2202-8-s3-s1] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Smell is often regarded as an ancillary perception in primates, who seem so dominated by their sense of vision. In this paper, we will portray some aspects of the significance of olfaction to human life and speculate on what evolutionary factors contribute to keeping it alive. We then outline the functional architecture of olfactory sensory neurons and their signal transduction pathways, which are the primary detectors that render olfactory perception possible. Throughout the phylogenetic tree, olfactory neurons, at their apical tip, are either decorated with cilia or with microvilli. The significance of this dichotomy is unknown. It is generally assumed that mammalian olfactory neurons are of the ciliary type only. The existence of so-called olfactory microvillar cells in mammals, however, is well documented, but their nature remains unclear and their function orphaned. This paper discusses the possibility, that in the main olfactory epithelium of mammals ciliated and microvillar sensory cells exist concurrently. We review evidence related to this hypothesis and ask, what function olfactory microvillar cells might have and what signalling mechanisms they use.
Collapse
Affiliation(s)
- Rebecca Elsaesser
- Johns Hopkins University School of Medicine, 725 N. Wolfe St., 408 WBSB, Baltimore, MD 21205, USA
| | - Jacques Paysan
- Technical University of Darmstadt, Institute of Zoology, Schnittspahnstrasse 3, D-64287 Darmstadt, Germany
| |
Collapse
|
35
|
Tatur S, Groulx N, Orlov SN, Grygorczyk R. Ca2+-dependent ATP release from A549 cells involves synergistic autocrine stimulation by coreleased uridine nucleotides. J Physiol 2007; 584:419-35. [PMID: 17702822 PMCID: PMC2277166 DOI: 10.1113/jphysiol.2007.133314] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Extracellular ATP is a potent surfactant secretagogue but its origin in the alveolus, its mechanism(s) of release and its regulatory pathways remain unknown. Previously, we showed that hypotonic swelling of alveolar A549 cells induces Ca(2+)-dependent secretion of several adenosine and uridine nucleotides, implicating regulated exocytosis. In this study, we examined sources of Ca(2+) for the elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)) evoked by acute 50% hypotonic stress and the role of autocrine purinergic signalling in Ca(2+)-dependent ATP release. We found that ATP release does not directly involve Ca(2+) influx from extracellular spaces, but depends entirely on Ca(2+) mobilization from intracellular stores. The [Ca(2+)](i) response consisted of slowly rising elevation, representing mobilization from thapsigargin (TG)-insensitive stores and a superimposed rapid spike due to Ca(2+) release from TG-sensitive endoplasmic reticulum (ER) Ca(2+) stores. The latter could be abolished by hydrolysis of extracellular triphospho- and diphosphonucleotides with apyrase; blocking P2Y(2)/P2Y(6) receptors of A549 cells with suramin; blocking UDP receptors (P2Y(6)) with pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid (PPADS); emptying TG-sensitive stores downstream with TG or caffeine in Ca(2+)-free extracellular solution; or blocking the Ca(2+)-release inositol 1,4,5-triphosphate receptor channel of the ER with 2-aminoethyldiphenylborinate. These data demonstrate that the rapid [Ca(2+)](i) spike results from the autocrine stimulation of IP(3)/Ca(2+)-coupled P2Y, predominantly P2Y(6), receptors, accounting for approximately 70% of total Ca(2+)-dependent ATP release evoked by hypotonic shock. Our study reveals a novel paradigm in which stress-induced ATP release from alveolar cells is amplified by the synergistic autocrine/paracrine action of coreleased uridine and adenosine nucleotides. We suggest that a similar mechanism of purinergic signal propagation operates in other cell types.
Collapse
Affiliation(s)
- Sabina Tatur
- Centre hospitalier de l'Université de Montréal - Hôtel-Dieu, 3850 Saint-Urbain, Montréal, Québec, Canada
| | | | | | | |
Collapse
|
36
|
HENLEY WILLIAMF, NEVES RICHARDJ, CACECI THOMAS, SAACKE RICHARDG. Anatomical descriptions and comparison of the reproductive tracts ofUtterbackia imbecillisandVillosa iris(Bivalvia: Unionidae). INVERTEBR REPROD DEV 2007. [DOI: 10.1080/07924259.2007.9652221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
37
|
Lange K, Gartzke J. F-actin-based Ca signaling-a critical comparison with the current concept of Ca signaling. J Cell Physiol 2006; 209:270-87. [PMID: 16823881 DOI: 10.1002/jcp.20717] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A short comparative survey on the current idea of Ca signaling and the alternative concept of F-actin-based Ca signaling is given. The two hypotheses differ in one central aspect, the mechanism of Ca storage. The current theory rests on the assumption of Ca-accumulating endoplasmic/sarcoplasmic reticulum-derived vesicles equipped with an ATP-dependent Ca pump and IP3- or ryanodine-sensitive channel-receptors for Ca-release. The alternative hypothesis proceeds from the idea of Ca storage at the high-affinity binding sites of actin filaments. Cellular sites of F-actin-based Ca storage are microvilli and the submembrane cytoskeleton. Several specific features of Ca signaling such as store-channel coupling, quantal Ca release, spiking and oscillations, biphasic and "phasic" uptake kinetics, and Ca-induced Ca release (CICR), which are not adequately described by the current concept, are inherent properties of the F-actin system and its dynamic state of treadmilling.
Collapse
|
38
|
Pritchard S, Guilak F. Effects of interleukin-1 on calcium signaling and the increase of filamentous actin in isolated and in situ articular chondrocytes. ACTA ACUST UNITED AC 2006; 54:2164-74. [PMID: 16802354 DOI: 10.1002/art.21941] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To determine whether interleukin-1 (IL-1) initiates transient changes in the intracellular concentration of [Ca2+]i and the organization of filamentous actin (F-actin) in articular chondrocytes. METHODS Articular chondrocytes within cartilage explants and enzymatically isolated chondrocytes were loaded with Ca(2+)-sensitive fluorescence indicators, and [Ca2+]i was measured using confocal fluorescence ratio imaging during exposure to 10 ng/ml IL-1alpha. Inhibitors of Ca2+ mobilization (Ca(2+)-free medium, thapsigargin [inhibitor of Ca-ATPases], U73122 [inhibitor of phospholipase C], and pertussis toxin [inhibitor of G proteins]) were used to determine the mechanisms of increased [Ca2+]i. Cellular F-actin was quantified using fluorescently labeled phalloidin. Toxin B was used to determine the role of the Rho family of small GTPases in F-actin reorganization. RESULTS In isolated cells on glass and in in situ chondrocytes within explants, exposure to IL-1 induced a transient peak in [Ca2+]i that was generally followed by a series of decaying oscillations. Thapsigargin, U73122, and pertussis toxin inhibited the percentage of cells responding to IL-1. IL-1 increased F-actin content in chondrocytes in a manner that was inhibited by toxin B. CONCLUSION Both isolated and in situ chondrocytes respond to IL-1 with transient increases in [Ca2+]i via intracellular Ca2+ release mediated by the phospholipase C and inositol trisphosphate pathways. The influx of Ca2+ from the extracellular space and the activation of G protein-coupled receptors also appear to contribute to these mechanisms. These findings suggest that Ca2+ mobilization may be one of the first signaling events in the response of chondrocytes to IL-1.
Collapse
Affiliation(s)
- Scott Pritchard
- Duke University Medical Center, 375 Medical Sciences Research Building, Research Drive, Durham, NC 27710, USA
| | | |
Collapse
|
39
|
Wang JW, Jiang YN, Huang CY, Huang PY, Huang MC, Cheng WTK, Shen CKJ, Ju YT. Proliferin enhances microvilli formation and cell growth of neuroblastoma cells. Neurosci Res 2006; 56:80-90. [PMID: 16876275 DOI: 10.1016/j.neures.2006.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 05/15/2006] [Accepted: 05/29/2006] [Indexed: 11/19/2022]
Abstract
Proliferins (also termed mitogen-regulated proteins; MRP/PLFs) belong to the prolactin gene family. Mrp/Plfs are involved in angiogenesis of the uterus and placenta and maximally expressed during midgestation and decline through the remainder of the gestation period in mouse placenta. The tissue expressions of Mrp/Plfs are mainly documented in placenta, hair follicles of skin and in wound healing. In this report, we demonstrate that Plf1, Plf1 minus exon3, Plf2 and Mrp3 but not Mrp4 are expressed in mouse whole brain by diagnostic RT-PCR and Western blotting. The expression levels of Mrp/Plf mRNAs in mouse brains were low during the neonatal period, but higher in embryonic and adult stages, indicating Mrp/Plfs expression profiles are different in mouse brain and placenta. Interestingly, endogenous Mrp/Plfs were detected using immunostaining both in mouse brain sections and the neuroblastoma cell line, Neuro-2a cells. The function of PLF1 was explored by expressing exogenous PLF1 in Neuro-2a cells. This resulted in increased microvilli. Neuro-2a cells with stable expression of PLF1 had increased proliferation compared with normal and stable expressing EGFP cells when cell reached saturation density. Together these data, strongly suggest that MRP/PLFs mediate microvilli formation and contribute to cell proliferation of neuroblastoma cells.
Collapse
Affiliation(s)
- Jyhi-Wai Wang
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan, ROC
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Nusco GA, Chun JT, Ercolano E, Lim D, Gragnaniello G, Kyozuka K, Santella L. Modulation of calcium signalling by the actin-binding protein cofilin. Biochem Biophys Res Commun 2006; 348:109-14. [PMID: 16875665 DOI: 10.1016/j.bbrc.2006.07.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 07/03/2006] [Indexed: 10/24/2022]
Abstract
Cofilin is a small protein that belongs to the family of actin-depolymerizing factors (ADF). The main cellular function of cofilin is to change cytoskeletal dynamics and thus to modulate cell motility and cytokinesis. We have recently demonstrated that the actin cytoskeleton is involved in the modulation of Ca(2+) signalling in starfish oocytes. To extend these observations, we have explored whether cofilin influences Ca(2+) signalling in the oocytes. Here we show that microinjection of the functionally active cofilin alters the Ca(2+) signalling mediated by the three major second messengers, InsP(3), NAADP, and cADPr. Cofilin intensifies the Ca(2+) signals induced by InsP(3) and NAADP, and delays those induced by cADPr. Furthermore, the injection of cofilin increases the Ca(2+) signals during hormone-induced oocyte maturation and fertilization. The results suggest that the dynamic regulation of F-actin by its binding proteins may play an important role in the modulation of intracellular Ca(2+) signalling.
Collapse
Affiliation(s)
- Gilda A Nusco
- Cell Signalling Laboratory, Stazione Zoologica Anton Dohrn Villa Comunale, I-80121 Naples, Italy
| | | | | | | | | | | | | |
Collapse
|
41
|
Teodori L, Albertini MC, Uguccioni F, Falcieri E, Rocchi MBL, Battistelli M, Coluzza C, Piantanida G, Bergamaschi A, Magrini A, Mucciato R, Accorsi A. Static magnetic fields affect cell size, shape, orientation, and membrane surface of human glioblastoma cells, as demonstrated by electron, optic, and atomic force microscopy. Cytometry A 2006; 69:75-85. [PMID: 16419064 DOI: 10.1002/cyto.a.20208] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND It is common knowledge that static magnetic fields (SMF) do not interact with living cells; thus, fewer studies of SMF compared with variable magnetic fields are carried out. However, evidence demonstrated that SMF affect cellular structures. To investigate the effect of exposure to increasing doses of SMF on cell morphology, human glioblastoma cells were exposed to SMF ranging between 80 and 3,000 G (8 and 300 mT). METHODS Cell morphology of human glioblastoma cells, derived from a primary culture, was studied by electron and optic microscopy. FITC-phalloidin staining of actin filaments was also investigated. Finally, cell surface structure changes were detected by atomic force microscopy. RESULTS Scanning electron microscopy demonstrated a dose-dependent cell shape modification, progressive cell detachment, loss of the long villi, and appearance of membrane roughness and blebs. FITC-phalloidin staining confirmed the villi retention and cell dimension decrease. At 3,000 G, the appearance of apoptotic morphology was also observed by transmission electron microscopy. Cell exposed to SMF showed different orientation and alignment when compared with nonexposed cells. The atomic force microscopy of the exposed cells' membrane surfaces demonstrated the disappearance of the ordered surface ripples and furrows typical of the unexposed cells, and the occurrence of surface membrane corrugation at increasing dose exposure CONCLUSIONS Our experimental procedures demonstrated that exposure to SMF affects not only cell size, shape, and orientation but also human glioblastoma cells' membrane surfaces.
Collapse
Affiliation(s)
- Laura Teodori
- Unità di Biotecnologie, Sezione di Tossicologia e Scienze Biomediche, ENEA Centro ricerche Casaccia, Via Anguillarese 301, 00060 Rome, Italy.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Abstract
Current research suggests that imbalances in metal-ion homeostasis play a critical role in neurodegenerative disorders, such as Alzheimer's disease and transmissible spongiform encephalopathy, and in cancer. It is thus important to elucidate the mechanisms by which homeostasis is maintained and how metals function in cellular processes, including cell signaling, neurotransmission, and protein transport and storage. This summary of a meeting recently held in Barcelona, Spain, highlights some of the latest findings on intra- and extracellular zinc signaling, the consequences of zinc imbalances on cells and on the brain, the mechanisms of metal-ion influx and efflux, how metal ions are sequestered by metallothioneins, and the development of candidate drugs to treat brain injury due to metal-ion imbalances.
Collapse
Affiliation(s)
- Carina Treiber
- Freie University of Berlin, Thielallee 63, 14195 Berlin, Germany.
| |
Collapse
|
43
|
Abstract
Many abiotic and other signals are transduced in eukaryotic cells by changes in the level of free calcium via pumps, channels and stores. We suggest here that ion condensation should also be taken into account. Calcium, like other counterions, is condensed onto linear polymers at a critical value of the charge density. Such condensation resembles a phase transition and has a topological basis in that it is promoted by linear as opposed to spherical assemblies of charges. Condensed counterions are delocalised and can diffuse in the so-called near region along the polymers. It is generally admitted that cytoskeletal filaments, proteins colocalised with these filaments, protein filaments distinct from cytoskeletal filaments, and filamentous assemblies of other macromolecules, constitute an intracellular macromolecular network. Here we draw attention to the fact that this network has physicochemical characteristics that enable counterion condensation. We then propose a model in which the feedback relationships between the condensation/decondensation of calcium and the activation of calcium-dependent kinases and phosphatases control the charge density of the filaments of the intracellular macromolecular network. We show how condensation might help mediate free levels of calcium both locally and globally. In this model, calcium condensation/decondensation on the macromolecular network creates coherent patterns of protein phosphorylation that integrate signals. This leads us to hypothesize that the process of ion condensation operates in signal transduction, that it can have an integrative role and that the macromolecular network serves as an integrative receptor.
Collapse
Affiliation(s)
- Camille Ripoll
- Laboratoire Assemblages Moléculaires: Modélisation et Imagerie SIMS, FRE CNRS 2829, Faculté des Sciences de l'Université de Rouen, Mont Saint Aignan, France.
| | | | | |
Collapse
|
44
|
Erickson GR, Northrup DL, Guilak F. Hypo-osmotic stress induces calcium-dependent actin reorganization in articular chondrocytes. Osteoarthritis Cartilage 2003; 11:187-97. [PMID: 12623290 DOI: 10.1053/s1063-4584(02)00347-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The aim of this study was to investigate the effects of hypo-osmotically induced calcium (Ca(2+)) transients on the organization of the actin cytoskeleton in articular chondrocytes. The secondary hypothesis tested was that actin restructuring following hypo-osmotic stress is mediated by gelsolin. METHODS Isolated porcine chondrocytes were exposed to hypo-osmotic stress, and [Ca(2+)](i)was monitored using laser scanning microscopy. Calcium transients were monitored using fluorescent ratiometric imaging. The intracellular distribution of actin was examined using fluorescent immunohistochemistry and transient transfection with the pEGFP-actin plasmid. The intracellular distribution of gelsolin was investigated using fluorescent immunohistochemistry. RESULTS Osmotic stress induced transient increases in [Ca(2+)](i)caused reorganization of intracellular actin through a mechanism that required Ca(2+)in the extracellular media. Fluorescence microscopy revealed that gelsolin was colocalized with F-actin immediately following hypo-osmotic stress but dissociated over time. CONCLUSION These results indicate that hypo-osmotic stress induces a gelsolin-mediated reorganization of actin through a transient increase in [Ca(2+)](i).
Collapse
Affiliation(s)
- G R Erickson
- Orthopaedic Research Laboratories, Department of Surgery, Duke University Medical Center, 27710, Durham,NC, USA
| | | | | |
Collapse
|
45
|
Abstract
Many organs are composed of epithelial tubes that transport vital fluids. Such tubular organs develop in many different ways and generate tubes of widely varying sizes and structures, but always with the apical epithelial surface lining the lumen. We describe recent progress in several diverse cell culture and genetic models of tube morphogenesis, which suggest apical membrane biogenesis, vesicle fusion, and secretion play central roles in tube formation and growth. We propose a unifying mechanism of tube morphogenesis that has been modified to create tube diversity and describe how defects in the tube size-sensing step can lead to polycystic kidney disease.
Collapse
Affiliation(s)
- Barry Lubarsky
- Howard Hughes Medical Institute, Department of Biochemistry, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | | |
Collapse
|
46
|
Pritchard S, Erickson GR, Guilak F. Hyperosmotically induced volume change and calcium signaling in intervertebral disk cells: the role of the actin cytoskeleton. Biophys J 2002; 83:2502-10. [PMID: 12414684 PMCID: PMC1302336 DOI: 10.1016/s0006-3495(02)75261-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Loading of the spine alters the osmotic environment in the intervertebral disk (IVD) as interstitial water is expressed from the tissue. Cells from the three zones of the IVD, the anulus fibrosus (AF), transition zone (TZ), and nucleus pulposus (NP), respond to osmotic stress with altered biosynthesis through a pathway that may involve calcium (Ca(2+)) as a second messenger. We examined the hypothesis that IVD cells respond to hyperosmotic stress by increasing the concentration of intracellular calcium ([Ca(2+)](i)) through a mechanism involving F-actin. In response to hyperosmotic stress, control cells from all zones decreased in volume and cells from the AF and TZ exhibited [Ca(2+)](i) transients, while cells from the NP did not. Extracellular Ca(2+) was necessary to initiate [Ca(2+)](i) transients. Stabilization of F-actin with phalloidin prevented the Ca(2+) response in AF and TZ cells and decreased the rate of volume change in cells from all zones, coupled with an increase in the elastic moduli and apparent viscosity. Conversely, actin breakdown with cytochalasin D facilitated Ca(2+) signaling while decreasing the elastic moduli and apparent viscosity for NP cells. These results suggest that hyperosmotic stress induces volume change in IVD cells and may initiate [Ca(2+)](i) transients through an actin-dependent mechanism.
Collapse
Affiliation(s)
- Scott Pritchard
- Department of Surgery, Duke University Medical Center, 374 Medical Sciences Research Building, Durham, NC 27710, USA
| | | | | |
Collapse
|
47
|
Gartzke J, Lange K. Cellular target of weak magnetic fields: ionic conduction along actin filaments of microvilli. Am J Physiol Cell Physiol 2002; 283:C1333-46. [PMID: 12372794 DOI: 10.1152/ajpcell.00167.2002] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of weak electromagnetic fields (EMF) with living cells is a most important but still unresolved biophysical problem. For this interaction, thermal and other types of noise appear to cause severe restrictions in the action of weak signals on relevant components of the cell. A recently presented general concept of regulation of ion and substrate pathways through microvilli provides a possible theoretical basis for the comprehension of physiological effects of even extremely low magnetic fields. The actin-based core of microfilaments in microvilli is proposed to represent a cellular interaction site for magnetic fields. Both the central role of F-actin in Ca2+ signaling and its polyelectrolyte nature eliciting specific ion conduction properties render the microvillar actin filament bundle an ideal interaction site for magnetic and electric fields. Ion channels at the tip of microvilli are connected with the cytoplasm by a bundle of microfilaments forming a diffusion barrier system. Because of its polyelectrolyte nature, the microfilament core of microvilli allows Ca2+ entry into the cytoplasm via nonlinear cable-like cation conduction through arrays of condensed ion clouds. The interaction of ion clouds with periodically applied EMFs and field-induced cation pumping through the cascade of potential barriers on the F-actin polyelectrolyte follows well-known physical principles of ion-magnetic field (MF) interaction and signal discrimination as described by the stochastic resonance and Brownian motor hypotheses. The proposed interaction mechanism is in accord with our present knowledge about Ca2+ signaling as the biological main target of MFs and the postulated extreme sensitivity for coherent excitation by very low field energies within specific amplitude and frequency windows. Microvillar F-actin bundles shielded by a lipid membrane appear to function like electronic integration devices for signal-to-noise enhancement; the influence of coherent signals on cation transduction is amplified, whereas that of random noise is reduced.
Collapse
Affiliation(s)
- Joachim Gartzke
- Bundesanstalt für Arbeitsschutz und Arbeitsmedizin, D-10317 Berlin, Germany.
| | | |
Collapse
|
48
|
Yamane Y, Shiga H, Asou H, Ito E. GAP junctional channel inhibition alters actin organization and calcium propagation in rat cultured astrocytes. Neuroscience 2002; 112:593-603. [PMID: 12074901 DOI: 10.1016/s0306-4522(02)00095-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Astrocytes are connected by gap junctions, which provide intercellular pathways that allow a direct exchange of ions and small metabolites including second messengers and the propagation of electric currents. The roles of gap junctional communication on whole-cell morphology, cytoskeletal organization, and intercellular communication in astrocytes are not yet clear even in vitro, though there are many studies that have examined the active relation between gap junctions and actin filaments in astrocytes. Here we examined the effects of gap junction inhibitors, which do not interrupt the formation but rather the function of gap junctions, on whole-cell morphology, cytoskeletal organization, and intercellular communication in rat cultured astrocytes. Functional blockade of gap junctions during the formation of an astrocytic monolayer resulted in discordance of actin stress fibers between neighboring cells, even though whole-cell morphology of these cells did not change by such treatment. Mechanical stimulation-induced calcium wave propagation was significantly reduced in these actin-discordance cells even after thorough wash out. Differentiation of astrocytes in the presence of gap junction inhibitors was associated with morphological disarrangement among neighboring cells due to disordered alignment of actin stress fibers between cells.Our results indicate that gap junctional communication enables cell-to-cell coordination of actin stress fibers in astrocytes, thus enhancing intercellular communication through calcium spread.
Collapse
Affiliation(s)
- Y Yamane
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
| | | | | | | |
Collapse
|
49
|
Abstract
Actin depolymerization by latrunculin A (LAT-A) in mature starfish oocytes induces a massive calcium mobilization that results in the discharge of the cortical granules and in the elevation of the fertilization envelope. The Ca2+ liberation starts as a circumscribed subplasma membrane hotspot, which is followed by a flash of Ca2+ increase restricted to the cortical layer. Ca2+ propagates rapidly from these peripheral regions to the center of the oocyte, initiating calcium oscillations. Blockade of the inositol 1,4,5-trisphosphate receptors with heparin does not affect the liberation of Ca2+ at the initial hotspot or the cortical flash, but abolishes the centripetal spreading of the wave and the Ca2+ oscillations. In Ca2+-free medium, LAT-A also initiates Ca2+ release at a discrete cortical point, but then propagates throughout the cell without first forming the uniform cortical flash. The latter is thus linked to the influx of external Ca2+, somehow promoted by the depolymerization of cortical (microvillar) actin. The Ca2+ response to spermatozoa (i.e., peripheral hotspot, cortical flash, globalization of the signal) closely mimics that promoted by LAT-A. Thus, the initial cortical release of Ca2+ promoted by the sperm may be due to the depolymerization of actin.
Collapse
Affiliation(s)
- Dmitri Lim
- Laboratory of Cell Biology, Stazione Zoologica 'A. Dohrn' Villa Comunale I-80121, Naples, Italy
| | | | | |
Collapse
|
50
|
Abstract
The current flow of papers on intestinal structure, radiation science, and intestinal radiation response is reflected in the contents of this review. Multiparameter findings and changes in compartments, cells, or subcellular structure all contribute to the overall profile of the response. The well-recognized changes in proliferation, vessels, and fibrogenesis are accompanied by alterations in other compartments, such as neuroendocrine or immune components of the intestinal wall. The responses at the molecular level, such as in levels of hormones, cytokines, or neurotransmitters, are of fundamental importance. The intestine responds to localized radiation, or to changes in other organs that influence its structure or function: some structural parameters respond differently to different radiation schedules. Apart from radiation conditions, factors affecting the outcome include the pathophysiology of the irradiated subject and accompanying treatment or intervention. More progress in understanding the overall responses is expected in the next few years.
Collapse
Affiliation(s)
- K E Carr
- The Queen's University of Belfast and MRC Radiation and Genome Stability Unit, Didcot, Oxfordshire, United Kingdom
| |
Collapse
|