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Yu F, Courjaret R, Assaf L, Elmi A, Hammad A, Fisher M, Terasaki M, Machaca K. Mitochondria-ER contact sites expand during mitosis. iScience 2024; 27:109379. [PMID: 38510124 PMCID: PMC10951641 DOI: 10.1016/j.isci.2024.109379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/31/2024] [Accepted: 02/27/2024] [Indexed: 03/22/2024] Open
Abstract
Mitochondria-ER contact sites (MERCS) are involved in energy homeostasis, redox and Ca2+ signaling, and inflammation. MERCS are heavily studied; however, little is known about their regulation during mitosis. Here, we show that MERCS expand during mitosis in three cell types using various approaches, including transmission electron microscopy, serial EM coupled to 3D reconstruction, and a split GFP MERCS marker. We further show enhanced Ca2+ transfer between the ER and mitochondria using either direct Ca2+ measurements or by quantifying the activity of Ca2+-dependent mitochondrial dehydrogenases. Collectively, our results support a lengthening of MERCS in mitosis that is associated with improved Ca2+ coupling between the two organelles. This augmented Ca2+ coupling could be important to support the increased energy needs of the cell during mitosis.
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Affiliation(s)
- Fang Yu
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Raphael Courjaret
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Lama Assaf
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
- College of Health and Life Science, Hamad bin Khalifa University, Doha, Qatar
| | - Asha Elmi
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
- College of Health and Life Science, Hamad bin Khalifa University, Doha, Qatar
| | - Ayat Hammad
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
- College of Health and Life Science, Hamad bin Khalifa University, Doha, Qatar
| | - Melanie Fisher
- Department of Cell Biology, UConn Health, 263 Farmington Ave, Farmington, CT 06030, USA
| | - Mark Terasaki
- Department of Cell Biology, UConn Health, 263 Farmington Ave, Farmington, CT 06030, USA
| | - Khaled Machaca
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
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2
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Fujii Y, Okabe I, Hatori A, Sah SK, Kanaujiya J, Fisher M, Norris R, Terasaki M, Reichenberger EJ, Chen IP. Skeletal abnormalities caused by a Connexin43 R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia. Res Sq 2024:rs.3.rs-3906170. [PMID: 38405920 PMCID: PMC10889043 DOI: 10.21203/rs.3.rs-3906170/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Craniometaphyseal dysplasia (CMD), a rare craniotubular disorder, occurs in an autosomal dominant (AD) or autosomal recessive (AR) form. CMD is characterized by hyperostosis of craniofacial bones and flaring metaphyses of long bones. Many patients with CMD suffer from neurological symptoms. To date, the pathogenesis of CMD is not fully understood. Treatment is limited to decompression surgery. Here, we report a knock in (KI) mouse model for AR CMD carrying a R239Q mutation in CX43. Cx43KI/KI mice replicate many features of AR CMD in craniofacial and long bones. In contrast to Cx43+/+ littermates, Cx43KI/KI mice exhibit periosteal bone deposition and increased osteoclast (OC) numbers in the endosteum of long bones, leading to an expanded bone marrow cavity and increased cortical bone thickness. Although formation of Cx43+/+ and Cx43KI/KI resting OCs are comparable, on bone chips the actively resorbing Cx43KI/KI OCs resorb less bone. Cortical bones of Cx43KI/KI mice have an increase in degenerating osteocytes and empty lacunae. Osteocyte dendrite formation is decreased with reduced expression levels of Fgf23, Sost, Tnf-α, IL-1β, Esr1, Esr2, and a lower Rankl/Opg ratio. Female Cx43KI/KI mice display a more severe phenotype. Sexual dimorphism in bone becomes more evident as mice age. Our data show that the CX43R239Q mutation results in mislocalization of CX43 protein and impairment of gap junction and hemichannel activity. Different from CX43 ablation mouse models, the CX43R239Q mutation leads to the AR CMD-like phenotype in Cx43KI/KI mice not only by loss-of-function but also via a not yet revealed dominant function.
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Affiliation(s)
- Yasuyuki Fujii
- Department of Endodontology, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Iichiro Okabe
- Department of Endodontology, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Ayano Hatori
- Department of Endodontology, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Shyam Kishor Sah
- Department of Endodontology, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Jitendra Kanaujiya
- Department of Cell Biology, University of Connecticut Health, Farmington, CT, United States
| | - Melanie Fisher
- Department of Cell Biology, University of Connecticut Health, Farmington, CT, United States
| | - Rachael Norris
- Department of Cell Biology, University of Connecticut Health, Farmington, CT, United States
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health, Farmington, CT, United States
| | - Ernst J. Reichenberger
- Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
| | - I-Ping Chen
- Department of Endodontology, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
- Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine, University of Connecticut Health, Farmington, CT, United States
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3
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Furusho M, Terasaki M. Evidence for glia-mediated, age-dependent remodeling of myelin at the axon initial segment. J Comp Neurol 2024; 532:e25574. [PMID: 38411251 DOI: 10.1002/cne.25574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 11/02/2023] [Accepted: 12/07/2023] [Indexed: 02/28/2024]
Abstract
Due to its proximity to the axon initial segment (AIS), the paranode of the first myelin segment can influence the threshold for action potentials and how a neuron participates in a neuronal circuit. Using serial section electron microscopy, we examined its three-dimensional (3D) organization in the ventral horn of the mouse spinal cord. The myelin loops of postnatal day 18 mice resemble those at the node of Ranvier. However, in 3-month-old mice, 13 of 22 para-AIS showed 4 types of alteration: (A) A cytoplasmic foot process, with ultrastructural characteristics of an astrocyte, was interposed between the axolemma and the myelin loops. (B) A thin extension of the inner tongue was present between the foot process and axolemma. (C) The foot process was absent. The inner tongue extension was a broad lamella from which a thin extension reached beyond the loops and spiraled around axon. (D) One set of loops was adjacent to the axon, and another was further back and underlain by compact myelin. We suggest that (A)-(C) are steps in a progression toward (D). In this progression, a glial process displaces the original loops, the inner tongue reactivates and extends beneath the foot process, then wraps around the axon to form a new set of loops. This is the first study of the 3D organization of myelin at the AIS and provides evidence for glia-mediated age-dependent remodeling at this critical region.
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Affiliation(s)
- Miki Furusho
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
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4
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Affiliation(s)
- Mayu Inaba
- Department of Cell Biology, University of Connecticut Health Center, CT, USA.
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, CT, USA
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5
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Wood BM, Baena V, Huang H, Jorgens DM, Terasaki M, Kornberg TB. Cytonemes with complex geometries and composition extend into invaginations of target cells. J Cell Biol 2021; 220:211896. [PMID: 33734293 PMCID: PMC7980254 DOI: 10.1083/jcb.202101116] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 12/16/2022] Open
Abstract
Cytonemes are specialized filopodia that mediate paracrine signaling in Drosophila and other animals. Studies using fluorescence confocal microscopy (CM) established their general paths, cell targets, and essential roles in signaling. To investigate details unresolvable by CM, we used high-pressure freezing and EM to visualize cytoneme structures, paths, contents, and contacts. We observed cytonemes previously seen by CM in the Drosophila wing imaginal disc system, including disc, tracheal air sac primordium (ASP), and myoblast cytonemes, and identified cytonemes extending into invaginations of target cells, and cytonemes connecting ASP cells and connecting myoblasts. Diameters of cytoneme shafts vary between repeating wide (206 ± 51.8 nm) and thin (55.9 ± 16.2 nm) segments. Actin, ribosomes, and membranous compartments are present throughout; rough ER and mitochondria are in wider proximal sections. These results reveal novel structural features of filopodia and provide a basis for understanding cytoneme cell biology and function.
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Affiliation(s)
- Brent M Wood
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT
| | - Hai Huang
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
| | - Danielle M Jorgens
- Electron Microscope Laboratory, University of California, Berkeley, Berkeley, CA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT
| | - Thomas B Kornberg
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
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6
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Norris RP, Terasaki M. Gap junction internalization and processing in vivo: a 3D immuno-electron microscopy study. J Cell Sci 2021; 134:jcs252726. [PMID: 33277382 DOI: 10.1242/jcs.252726] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/26/2020] [Indexed: 12/15/2022] Open
Abstract
Gap junctions have well-established roles in cell-cell communication by way of forming permeable intercellular channels. Less is understood about their internalization, which forms double membrane vesicles containing cytosol and membranes from another cell called connexosomes or annular gap junctions. Here, we systematically investigated the fate of connexosomes in intact ovarian follicles. High-pressure frozen, serial-sectioned tissue was immunogold labeled for connexin 43 (Cx43, also known as GJA1). Within a volume corresponding to ∼35 cells, every labeled structure was categorized and had its surface area measured. Measurements support the concept that multiple connexosomes form from larger invaginated gap junctions. Subsequently, the inner and outer membranes separate, Cx43 immunogenicity is lost from the outer membrane, and the inner membrane appears to undergo fission. One pathway for processing involves lysosomes, based on localization of cathepsin B to some processed connexosomes. In summary, this study demonstrates new technology for high-resolution analyses of gap junction processing.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Rachael P Norris
- Department of Cell Biology, UConn Health, 263 Farmington Ave, Farmington, CT 06030, USA
| | - Mark Terasaki
- Department of Cell Biology, UConn Health, 263 Farmington Ave, Farmington, CT 06030, USA
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7
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Abstract
The Drosophila ovary is an exceptional model for studying cell-cell interactions in vivo. Cells communicate with each other in a highly coordinated manner. Accurate spatiotemporal regulation of cell-cell interaction is critical for the development of eggs. Ultrastructural analysis using electron microscopy (EM) permits the visualization of both cells and subcellular signaling structures with high resolution. Here we describe a method for the processing of intact fly ovaries by scanning electron microscopy (SEM).
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Affiliation(s)
- Matthew Antel
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Mayu Inaba
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA.
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8
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Shuhaibar N, Hand AR, Terasaki M. Odontoblast processes of the mouse incisor are plates oriented in the direction of growth. Anat Rec (Hoboken) 2020; 304:1820-1827. [PMID: 33190419 PMCID: PMC8359275 DOI: 10.1002/ar.24570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/11/2020] [Accepted: 09/11/2020] [Indexed: 12/18/2022]
Abstract
Odontoblast processes are thin cytoplasmic projections that extend from the cell body at the periphery of the pulp toward the dentin-enamel junction. The odontoblast processes function in the secretion, assembly and mineralization of dentin during development, participate in mechanosensation, and aid in dentin repair in mature teeth. Because they are small and densely arranged, their three-dimensional organization is not well documented. To gain further insight into how odontoblast processes contribute to odontogenesis, we used serial section electron microscopy and three-dimensional reconstructions to examine these processes in the predentin region of mouse molars and incisors. In molars, the odontoblast processes are tubular with a diameter of ~1.8 μm. The odontoblast processes near the incisor tip are similarly shaped, but those midway between the tip and apex are shaped like plates. The plates are radially aligned and longitudinally oriented with respect to the growth axis of the incisor. The thickness of the plates is approximately the same as the diameter of molar odontoblast processes. The plates have an irregular edge; the average ratio of width (midway in the predentin) to thickness is 2.3 on the labial side and 3.6 on the lingual side. The plate geometry seems likely to be related to the continuous growth of the incisor and may provide a clue as to the mechanisms by which the odontoblast processes are involved in tooth development.
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Affiliation(s)
- Ninna Shuhaibar
- Department of Cell Biology, University of Connecticut Health, Farmington, Connecticut, USA
| | - Arthur R Hand
- Department of Cell Biology, University of Connecticut Health, Farmington, Connecticut, USA.,Division of Craniofacial Sciences, University of Connecticut Health, Farmington, Connecticut, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health, Farmington, Connecticut, USA
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9
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Terasaki M, Brunson JC, Sardi J. Analysis of the three dimensional structure of the kidney glomerulus capillary network. Sci Rep 2020; 10:20334. [PMID: 33230129 PMCID: PMC7683536 DOI: 10.1038/s41598-020-77211-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 11/05/2020] [Indexed: 12/30/2022] Open
Abstract
The capillary network of the kidney glomerulus filters small molecules from the blood. The glomerular 3D structure should help to understand its function, but it is poorly characterized. We therefore devised a new approach in which an automated tape collecting microtome (ATUM) was used to collect 0.5 μm thick serial sections from fixed mouse kidneys. The sections were imaged by scanning electron microscopy at ~ 50 nm/pixel resolution. With this approach, 12 glomeruli were reconstructed at an x–y–z resolution ~ 10 × higher than that of paraffin sections. We found a previously undescribed no-cross zone between afferent and efferent branches on the vascular pole side; connections here would allow blood to exit without being adequately filtered. The capillary diameters throughout the glomerulus appeared to correspond with the amount of blood flow within them. The shortest path (minimum number of branches to travel from afferent to efferent arterioles) is relatively independent of glomerular size and is present primarily on the vascular pole size. This suggests that new branches and longer paths form on the urinary pole side. Network analysis indicates that the glomerular network does not form by repetitive longitudinal splitting of capillaries. Thus the 3D structure of the glomerular capillary network provides useful information with which to understand glomerular function. Other tissue structures in the body may benefit from this new three dimensional approach.
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Affiliation(s)
- Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, 06030, USA.
| | - Jason Cory Brunson
- Laboratory for Systems Medicine, University of Florida Health, Gainesville, FL, 32610, USA
| | - Justin Sardi
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, 06030, USA
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10
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Baena V, Owen CM, Uliasz TF, Lowther KM, Yee SP, Terasaki M, Egbert JR, Jaffe LA. Cellular Heterogeneity of the Luteinizing Hormone Receptor and Its Significance for Cyclic GMP Signaling in Mouse Preovulatory Follicles. Endocrinology 2020; 161:5834711. [PMID: 32384146 PMCID: PMC7574965 DOI: 10.1210/endocr/bqaa074] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 05/02/2020] [Indexed: 12/14/2022]
Abstract
Meiotic arrest and resumption in mammalian oocytes are regulated by 2 opposing signaling proteins in the cells of the surrounding follicle: the guanylyl cyclase natriuretic peptide receptor 2 (NPR2), and the luteinizing hormone receptor (LHR). NPR2 maintains a meiosis-inhibitory level of cyclic guanosine 5'-monophosphate (cGMP) until LHR signaling causes dephosphorylation of NPR2, reducing NPR2 activity, lowering cGMP to a level that releases meiotic arrest. However, the signaling pathway between LHR activation and NPR2 dephosphorylation remains incompletely understood, due in part to imprecise information about the cellular localization of these 2 proteins. To investigate their localization, we generated mouse lines in which hemagglutinin epitope tags were added to the endogenous LHR and NPR2 proteins, and used immunofluorescence and immunogold microscopy to localize these proteins with high resolution. The results showed that the LHR protein is absent from the cumulus cells and inner mural granulosa cells, and is present in only 13% to 48% of the outer mural granulosa cells. In contrast, NPR2 is present throughout the follicle, and is more concentrated in the cumulus cells. Less than 20% of the NPR2 is in the same cells that express the LHR. These results suggest that to account for the LH-induced inactivation of NPR2, LHR-expressing cells send a signal that inactivates NPR2 in neighboring cells that do not express the LHR. An inhibitor of gap junction permeability attenuates the LH-induced cGMP decrease in the outer mural granulosa cells, consistent with this mechanism contributing to how NPR2 is inactivated in cells that do not express the LHR.
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Affiliation(s)
- Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Corie M Owen
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Tracy F Uliasz
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Katie M Lowther
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Siu-Pok Yee
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Jeremy R Egbert
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Laurinda A Jaffe
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
- Correspondence: Laurinda A. Jaffe, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030 USA. E-mail:
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11
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Iyer R, Monfredi O, Lavorato M, Terasaki M, Franzini‐Armstrong C. Ultrastructure of primary pacemaking cells in rabbit sino-atrial node cells indicates limited sarcoplasmic reticulum content. FASEB Bioadv 2020; 2:106-115. [PMID: 32123860 PMCID: PMC7003656 DOI: 10.1096/fba.2018-00079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 12/20/2018] [Accepted: 11/25/2019] [Indexed: 11/21/2022] Open
Abstract
The main mammalian heart pacemakers are spindle-shaped cells compressed into tangles within protective layers of collagen in the sino-atrial node (SAN). Two cell types, "dark" and "light," differ on their high or low content of intermediate filaments, but share scarcity of myofibrils and a high content of glycogen. Sarcoplasmic reticulum (SR) is scarce. The free SR (fSR) occupies 0.04% of the cell volume within ~0.4 µm wide peripheral band. The junctional SR (jSR), constituting peripheral couplings (PCs), occupies 0.03% of the cell volume. Total fSR + jSR volume is 0.07% of cell volume, lower than the SR content of ventricular myocytes. The average distance between PCs is 7.6 µm along the periphery. On the average, 30% of the SAN cells surfaces is in close proximity to others. Identifiable gap junctions are extremely rare, but small sites of close membrane-to-membrane contacts are observed. Possibly communication occurs via these very small sites of contact if conducting channels (connexons) are located within them. There is no obvious anatomical detail that might support ephaptic coupling. These observations have implications for understanding of SAN cell physiology, and require incorporation into biophysically detailed models of SAN cell behavior that currently do not include such features.
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Affiliation(s)
- Ramesh Iyer
- Division of CardiologyChildren Hospital of PhiladelphiaPhiladelphiaPAUSA
| | - Oliver Monfredi
- Laboratory of Cardiovascular SciencesNIA IRP NIHBaltimoreMDUSA
- The Johns Hopkins HospitalDepartment of CardiologyBaltimoreMDUSA
| | - Manuela Lavorato
- Department of Cell and Developmental BiologyUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Mark Terasaki
- Department of Cell BiologyUniversity of Connecticut Health CenterFarmingtonCTUSA
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12
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Rawlinson KA, Lapraz F, Ballister ER, Terasaki M, Rodgers J, McDowell RJ, Girstmair J, Criswell KE, Boldogkoi M, Simpson F, Goulding D, Cormie C, Hall B, Lucas RJ, Telford MJ. Extraocular, rod-like photoreceptors in a flatworm express xenopsin photopigment. eLife 2019; 8:45465. [PMID: 31635694 PMCID: PMC6805122 DOI: 10.7554/elife.45465] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 08/15/2019] [Indexed: 11/17/2022] Open
Abstract
Animals detect light using opsin photopigments. Xenopsin, a recently classified subtype of opsin, challenges our views on opsin and photoreceptor evolution. Originally thought to belong to the Gαi-coupled ciliary opsins, xenopsins are now understood to have diverged from ciliary opsins in pre-bilaterian times, but little is known about the cells that deploy these proteins, or if they form a photopigment and drive phototransduction. We characterized xenopsin in a flatworm, Maritigrella crozieri, and found it expressed in ciliary cells of eyes in the larva, and in extraocular cells around the brain in the adult. These extraocular cells house hundreds of cilia in an intra-cellular vacuole (phaosome). Functional assays in human cells show Maritigrella xenopsin drives phototransduction primarily by coupling to Gαi. These findings highlight similarities between xenopsin and c-opsin and reveal a novel type of opsin-expressing cell that, like jawed vertebrate rods, encloses the ciliary membrane within their own plasma membrane. Eyes are elaborate organs that many animals use to detect light and see, but light can also be sensed in other, simpler ways and for purposes other than seeing. All animals that perceive light rely on cells called photoreceptors, which come in two main types: ciliary or rhabdomeric. Sometimes, an organism has both types of photoreceptors, but one is typically more important than the other. For example, most vertebrates see using ciliary photoreceptors, while rhabdomeric photoreceptors underpin vision in invertebrates. Flatworms are invertebrates that have long been studied due to their ability to regenerate following injuries. These worms have rhabdomeric photoreceptors in their eyes, but they also have unusual cells outside their eyes that have cilia – slender protuberances from the cell body - and could potentially be light sensitive. One obvious way to test if a cell is a photoreceptor is to see if it produces any light-sensing proteins, such as opsins. Until recently it was thought that each type of photoreceptor produced a different opsin, which were therefore classified into rhabdomeric of ciliary opsins. However, recent work has identified a new type of opsin, called xenopsin, in the ciliary photoreceptors of the larvae of some marine invertebrates. To determine whether the cells outside the flatworm’s eye were ciliary photoreceptors, Rawlinson et al. examined the genetic code of 30 flatworm species looking for ciliary opsin and xenopsin genes. This search revealed that all the flatworm species studied contained the genetic sequence for xenopsin, but not for the ciliary opsin. Rawlinson et al. chose the tiger flatworm to perform further experiments. First, they showed that, in this species, xenopsin genes are active both in the eyes of larvae and in the unusual ciliary cells found outside the eyes of the adult. Next, they put the xenopsin from the tiger flatworm into human embryonic kidney cells, and found that when the protein is present these cells can respond to light. This demonstrates that the newly discovered xenopsin is light-sensitive, suggesting that the unusual ciliary cells found expressing this protein outside the eyes in flatworms are likely photoreceptive cells. It is unclear why flatworms have developed these unusual ciliary photoreceptor cells or what their purpose is outside the eye. Often, photoreceptor cells outside the eyes are used to align the ‘body clock’ with the day-night cycle. This can be a factor in healing, hinting perhaps that these newly found cells may have a role in flatworms’ ability to regenerate.
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Affiliation(s)
- Kate A Rawlinson
- Wellcome Sanger Institute, Hinxton, United Kingdom.,Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Marine Biological Laboratory, Woods Hole, United States
| | - Francois Lapraz
- Université Côte D'Azur, CNRS, Institut de Biologie Valrose, Nice, France
| | - Edward R Ballister
- New York University School of Medicine, New York, United States.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Mark Terasaki
- Marine Biological Laboratory, Woods Hole, United States.,University of Connecticut Health Center, Farmington, United States
| | - Jessica Rodgers
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Richard J McDowell
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Johannes Girstmair
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Katharine E Criswell
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Marine Biological Laboratory, Woods Hole, United States
| | - Miklos Boldogkoi
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Fraser Simpson
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | | | | | - Brian Hall
- Department of Biology, Dalhousie University, Halifax, Canada
| | - Robert J Lucas
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Maximilian J Telford
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
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13
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Suekane S, Noguchi M, Terasaki M, Yutani S, Narita Y, Yamada A, Shichijo S, Igawa T, Itoh K. Biomarkers predictive of overall survival in advanced cancer patients treated with a peptide-based cancer vaccine. Ann Oncol 2019. [DOI: 10.1093/annonc/mdz239.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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14
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Yoshiyama K, Noguchi M, Terasaki M, Sugawara S, Yamada A, Shichijo S, Takamori S, Akagi Y, Yutani S, Itoh K. P2.04-65 Peptide-Based Cancer Vaccine Shortened the Overall Survival of a Large Portion, but Not All, of Advanced Cancer Patients. J Thorac Oncol 2019. [DOI: 10.1016/j.jtho.2019.08.1570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Abstract
The Automated Tape-Collecting Ultramicrotome (ATUM) is a tape-reeling device that is placed in a water-filled diamond knife boat to collect serial sections as they are cut by a conventional ultramicrotome. The ATUM can collect thousands of sections of many different shapes and sizes, which are subsequently imaged by a scanning electron microscope. This method has been used for large-scale connectomics projects of mouse brain, and is well suited for other smaller-scale studies of tissues, cells, and organisms. Here, we describe basic procedures for preparing a block for ATUM sectioning, handling of the ATUM, tape preparation, post-treatment of sections, and considerations for mapping, imaging, and aligning the serial sections.
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Affiliation(s)
- Valentina Baena
- Deparment of Cell Biology, University of Connecticut Health Center, Farmington, CT, United States
| | - Richard Lee Schalek
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA, United States
| | - Jeff William Lichtman
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA, United States
| | - Mark Terasaki
- Deparment of Cell Biology, University of Connecticut Health Center, Farmington, CT, United States.
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16
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Baena V, Terasaki M. Three-dimensional organization of transzonal projections and other cytoplasmic extensions in the mouse ovarian follicle. Sci Rep 2019; 9:1262. [PMID: 30718581 PMCID: PMC6362238 DOI: 10.1038/s41598-018-37766-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 12/07/2018] [Indexed: 02/07/2023] Open
Abstract
Each mammalian oocyte is nurtured by its own multi-cellular structure, the ovarian follicle. We used new methods for serial section electron microscopy to examine entire cumulus and mural granulosa cells and their projections in mouse antral ovarian follicles. Transzonal projections (TZPs) are thin cytoplasmic projections that connect cumulus cells to the oocyte and are crucial for normal oocyte development. We studied these projections in detail and found that most TZPs do not reach the oocyte, and that they often branch and make gap junctions with each other. Furthermore, the TZPs that connect to the oocyte are usually contacted on their shaft by oocyte microvilli. Mural granulosa cells were found to possess randomly oriented cytoplasmic projections that are strikingly similar to the free-ended TZPs. We propose that granulosa cells use cytoplasmic projections to search for the oocyte, and cumulus cell differentiation results from a contact-mediated paracrine interaction with the oocyte.
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Affiliation(s)
- Valentina Baena
- Department of Cell Biology, UConn Health, Farmington, CT, USA
| | - Mark Terasaki
- Department of Cell Biology, UConn Health, Farmington, CT, USA.
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17
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Niedenberger BA, Cook K, Baena V, Serra ND, Velte EK, Agno JE, Litwa KA, Terasaki M, Hermann BP, Matzuk MM, Geyer CB. Dynamic cytoplasmic projections connect mammalian spermatogonia in vivo. Development 2018; 145:dev161323. [PMID: 29980567 PMCID: PMC6110146 DOI: 10.1242/dev.161323] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 06/27/2018] [Indexed: 01/12/2023]
Abstract
Throughout the male reproductive lifespan, spermatogonial stem cells (SSCs) produce committed progenitors that proliferate and then remain physically connected in growing clones via short cylindrical intercellular bridges (ICBs). These ICBs, which enlarge in meiotic spermatocytes, have been demonstrated to provide a conduit for postmeiotic haploid spermatids to share sex chromosome-derived gene products. In addition to ICBs, spermatogonia exhibit multiple thin cytoplasmic projections. Here, we have explored the nature of these projections in mice and find that they are dynamic, span considerable distances from their cell body (≥25 μm), either terminate or physically connect multiple adjacent spermatogonia, and allow for sharing of macromolecules. Our results extend the current model that subsets of spermatogonia exist as isolated cells or clones, and support a model in which spermatogonia of similar developmental fates are functionally connected through a shared dynamic cytoplasm mediated by thin cytoplasmic projections.
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Affiliation(s)
- Bryan A Niedenberger
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Kenneth Cook
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Nicholas D Serra
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Ellen K Velte
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Julio E Agno
- Center for Drug Discovery and Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Karen A Litwa
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Brian P Hermann
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Martin M Matzuk
- Center for Drug Discovery and Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
- East Carolina Diabetes and Obesity Institute at East Carolina University, Greenville, NC 27834, USA
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18
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Abstract
The endoplasmic reticulum (ER) is an interconnected network of tubules and sheets. In most tissues of the body, ER tubules have a diameter of ∼60 nm. Using new methods for serial-section electron microscopy, a distinct class of very narrow, 20- to 30-nm-diameter tubules were found in neurons of both the central and peripheral nervous system. The narrow tubules appear to be the most abundant form of ER in axons, and are also found interspersed in the cell bodies and dendrites. At the site of branch points, there is a small sheet that has a similarly narrow lumen. The narrowness of the ER is likely to be important for the as yet poorly characterized functions of the axonal ER.
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Affiliation(s)
- Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
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19
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Terasaki A, Kurokawa H, Terasaki M, Ito H, Matsui H, Ichioka E, Tsushima Y, Manaka-Iguchi A, Bando H, Hara H. Abstract P1-05-05: Hyperthermia regulates transporter expression via ROS production and enhances the cytotoxicity of doxorubicin. Cancer Res 2018. [DOI: 10.1158/1538-7445.sabcs17-p1-05-05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Introduction: Hyperthermia (HT) is a non-invasive cancer therapy. Treatment temperature between 41°C to 44°C has no cytotoxic damage in normal cells, however shows cytotoxicity in cancer cells because of the underdeveloped vascular system. HT often used with other cancer therapy such as radiation therapy and chemotherapy. However mechanism of synergistic effect using these therapies remains unclear. Compared to 37°C, 42°C is mild heat stress for cells, thus superoxide anion is released from tissue. Superoxide anion is produced by mitochondrial electron transport chain. Reactive oxygen species (ROS), produced by mild heat stress, can be released from mitochondria. We have previously reported that ATP-binding cassette sub-family G member 2 (ABCG2) expression was suppressed by increasing mitochondrial ROS, and induction of the cancer specific porphyrin accumulation. ABCG2 is a transporter of doxorubicin (DOX), therefore we hypothesized that synergistic effect of HT and chemotherapy would be induced by down-regulation of ABCG2 expression via intracellular ROS increase. In this study, we investigated if cytotoxic effect of breast cancer cell using DOX can be enhance by HT via intracellular ROS increase.
Materials and methods: The murine breast cancer cell line, 4T1E was incubated at 37°C or 42°C for 1h. Intracellular ROS generation after HT treatment was detected by electron spin resonance (ESR). Twenty four hours after HT treatment, cells were incubated in medium containing 0, 0.1 and 1 μM DOX for 24 h. Cell viability was measured using the Cell Counting Kit 8, a water-soluble tetrazolium-8 based colorimetric assay. ABCG2 expression in whole cells was analyzed by Western blotting.
Results and discussion: ESR signal peak with HT treatment became high as compared to without HT treatment, indicating intracellular ROS level was increased by HT treatment. Cell viability and ABCG2 expression were decreased by DOX exposure and by HT treatment. The enhancement of HT treatment effect by DOX is considered to be result of down-regulation of ABCG2 expression by ROS. When cells were exposed to DOX with 5-aminolevulinic acid (ALA), cell viability reduced further. Since it is known that porphyrin is introduced by ALA and is transported by ABCG2, we speculate that ALA worked as a competitive inhibitor of DOX excretion transporter to enhance cell death. ESR signal peak in ALA treatment cells was higher than that in non-ALA treatment cells. Significant increase in cellular damage by HT treatment was shown by adding ALA, but not without ALA. Moreover, cell death induced by HT and ALA treatment was suppressed by adding N-acetylcysteine (NAC), which is an antioxidant. These results suggest that cellular damage of HT treatment is due to ROS production induced by ALA.
Conclusion: HT treatment involved intracellular ROS production and down-regulated the expression of ABCG2 protein. HT treatment also enhanced the cell damage by DOX. Cell death by DOX was enhanced by combination with HT and ALA treatment, possibly via intracellular ROS generation, and was suppressed by additing antioxidant.
Citation Format: Terasaki A, Kurokawa H, Terasaki M, Ito H, Matsui H, Ichioka E, Tsushima Y, Manaka-Iguchi A, Bando H, Hara H. Hyperthermia regulates transporter expression via ROS production and enhances the cytotoxicity of doxorubicin [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-05-05.
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Affiliation(s)
- A Terasaki
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - H Kurokawa
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - M Terasaki
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - H Ito
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - H Matsui
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - E Ichioka
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Y Tsushima
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - A Manaka-Iguchi
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - H Bando
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - H Hara
- University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan; Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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20
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Darras S, Fritzenwanker JH, Uhlinger KR, Farrelly E, Pani AM, Hurley IA, Norris RP, Osovitz M, Terasaki M, Wu M, Aronowicz J, Kirschner M, Gerhart JC, Lowe CJ. Anteroposterior axis patterning by early canonical Wnt signaling during hemichordate development. PLoS Biol 2018; 16:e2003698. [PMID: 29337984 PMCID: PMC5786327 DOI: 10.1371/journal.pbio.2003698] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 01/26/2018] [Accepted: 12/22/2017] [Indexed: 12/28/2022] Open
Abstract
The Wnt family of secreted proteins has been proposed to play a conserved role in early specification of the bilaterian anteroposterior (A/P) axis. This hypothesis is based predominantly on data from vertebrate embryogenesis as well as planarian regeneration and homeostasis, indicating that canonical Wnt (cWnt) signaling endows cells with positional information along the A/P axis. Outside of these phyla, there is strong support for a conserved role of cWnt signaling in the repression of anterior fates, but little comparative support for a conserved role in promotion of posterior fates. We further test the hypothesis by investigating the role of cWnt signaling during early patterning along the A/P axis of the hemichordate Saccoglossus kowalevskii. We have cloned and investigated the expression of the complete Wnt ligand and Frizzled receptor complement of S. kowalevskii during early development along with many secreted Wnt modifiers. Eleven of the 13 Wnt ligands are ectodermally expressed in overlapping domains, predominantly in the posterior, and Wnt antagonists are localized predominantly to the anterior ectoderm in a pattern reminiscent of their distribution in vertebrate embryos. Overexpression and knockdown experiments, in combination with embryological manipulations, establish the importance of cWnt signaling for repression of anterior fates and activation of mid-axial ectodermal fates during the early development of S. kowalevskii. However, surprisingly, terminal posterior fates, defined by posterior Hox genes, are unresponsive to manipulation of cWnt levels during the early establishment of the A/P axis at late blastula and early gastrula. We establish experimental support for a conserved role of Wnt signaling in the early specification of the A/P axis during deuterostome body plan diversification, and further build support for an ancestral role of this pathway in early evolution of the bilaterian A/P axis. We find strong support for a role of cWnt in suppression of anterior fates and promotion of mid-axial fates, but we find no evidence that cWnt signaling plays a role in the early specification of the most posterior axial fates in S. kowalevskii. This posterior autonomy may be a conserved feature of early deuterostome axis specification.
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Affiliation(s)
- Sébastien Darras
- Institut de Biologie du Développement de Marseille, Aix-Marseille Université, CNRS UMR 7288, Marseille, France
| | - Jens H. Fritzenwanker
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, California
| | - Kevin R. Uhlinger
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, California
| | - Ellyn Farrelly
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois
| | - Ariel M. Pani
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois
| | - Imogen A. Hurley
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois
| | - Rachael P. Norris
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Michelle Osovitz
- Department of Natural Sciences, St. Petersburg College, Clearwater, Florida
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Mike Wu
- Department of Molecular and Cellular Biology, University of California Berkeley, Berkeley, California
| | - Jochanan Aronowicz
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois
| | - Marc Kirschner
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts
| | - John C. Gerhart
- Department of Molecular and Cellular Biology, University of California Berkeley, Berkeley, California
| | - Christopher J. Lowe
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, California
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21
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Yalçın B, Zhao L, Stofanko M, O'Sullivan NC, Kang ZH, Roost A, Thomas MR, Zaessinger S, Blard O, Patto AL, Sohail A, Baena V, Terasaki M, O'Kane CJ. Modeling of axonal endoplasmic reticulum network by spastic paraplegia proteins. eLife 2017; 6. [PMID: 28742022 PMCID: PMC5576921 DOI: 10.7554/elife.23882] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 07/24/2017] [Indexed: 01/17/2023] Open
Abstract
Axons contain a smooth tubular endoplasmic reticulum (ER) network that is thought to be continuous with ER throughout the neuron; the mechanisms that form this axonal network are unknown. Mutations affecting reticulon or REEP proteins, with intramembrane hairpin domains that model ER membranes, cause an axon degenerative disease, hereditary spastic paraplegia (HSP). We show that Drosophila axons have a dynamic axonal ER network, which these proteins help to model. Loss of HSP hairpin proteins causes ER sheet expansion, partial loss of ER from distal motor axons, and occasional discontinuities in axonal ER. Ultrastructural analysis reveals an extensive ER network in axons, which shows larger and fewer tubules in larvae that lack reticulon and REEP proteins, consistent with loss of membrane curvature. Therefore HSP hairpin-containing proteins are required for shaping and continuity of axonal ER, thus suggesting roles for ER modeling in axon maintenance and function. DOI:http://dx.doi.org/10.7554/eLife.23882.001 The way we move – from simple motions like reaching out to grab something, to playing the piano or dancing – is coordinated in our brain. These processes involve many regions and steps, in which nerve cells transport signals along projections known as axons. Axons rely on sophisticated ‘engineering’ to work properly over long distances and are vulnerable to diseases that disrupt their engineering. For example, in genetic diseases called ‘hereditary spastic paraplegias’, damages to the ‘distal’ end of axons – the end furthest from the nerve cell body – cause paralysis of the lower body. Axons have several internal structures that make sure everything works properly. One of these structures is the endoplasmic reticulum, which is a network of tubular membranes that runs lengthwise along the axon. It is known that spastic paraplegias are sometimes caused by mutations affecting proteins that help to build and shape the endoplasmic reticulum, for example, the proteins of the reticulon and REEP families. However, until now it was not known how the ER forms its network in the axons and if this is influenced by these proteins. To see whether reticulons and REEPs affect the shape of the endoplasmic reticulum, Yalçιn et al. used healthy fruit fly larvae, and genetically modified ones that lacked the proteins. The results show that in healthy flies, the tubular network runs continuously along the axons. When either reticulon or REEP proteins were removed, the distal axons contained less endoplasmic reticulum. In mutant fly larvae that lacked both protein families, the endoplasmic reticulum was more interrupted and contained more gaps than in normal larvae. Using high-magnification electron microscopy confirmed these findings, and showed that the tubules of the endoplasmic reticulum in mutant axons were larger, but fewer. A next step will be to test whether these mutations also affect how the axons work and communicate over long distances. A better knowledge of the role of the endoplasmic reticulum in axons will help us to understand how damages to it could affect hereditary spastic paraplegias and other degenerative conditions. DOI:http://dx.doi.org/10.7554/eLife.23882.002
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Affiliation(s)
- Belgin Yalçın
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Lu Zhao
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Martin Stofanko
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Niamh C O'Sullivan
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Zi Han Kang
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Annika Roost
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Matthew R Thomas
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Sophie Zaessinger
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Olivier Blard
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Alex L Patto
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Anood Sohail
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, United States
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, United States
| | - Cahir J O'Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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22
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Norris RP, Baena V, Terasaki M. Localization of phosphorylated connexin 43 by serial section immunogold electron microscopy. J Cell Sci 2017; 130:1333-1340. [DOI: 10.1242/jcs.198408] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/09/2017] [Indexed: 02/05/2023] Open
Abstract
Gap junction turnover occurs by the internalization of both plasma membranes of a gap junction plaque to form a double membrane-enclosed vesicle, or connexosome. Phosphorylation has a key role in regulation, but further progress requires clearly distinguishing gap junctions and connexosomes and precisely localizing proteins to them. We examined by electron microscopy serial sections of mouse preovulatory ovarian follicles collected with an automated tape collecting ultramicrotome (ATUM). We found connexosomes may form from adjacent cell bodies, from thin cell processes, or from the same cell. By immunolabeling serial sections, we found S368 of connexin 43 is phosphorylated on gap junctions and connexosomes, whereas S262 is phosphorylated only on some connexosomes. These data suggest that S262 phosphorylation contributes to connexosome formation or processing, and provide more precise evidence that phosphorylation has a key role in gap junction internalization. Serial section electron microscopy of immunogold-labeled tissues offers a new way for investigating the three-dimensional organization of cells in their native environment.
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Affiliation(s)
- Rachael P. Norris
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
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24
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Lowe CJ, Terasaki M, Wu M, Freeman RM, Runft L, Kwan K, Haigo S, Aronowicz J, Lander E, Gruber C, Smith M, Kirschner M, Gerhart J. Correction: Dorsoventral Patterning in Hemichordates: Insights into Early Chordate Evolution. PLoS Biol 2015; 13:e1002354. [PMID: 26714185 PMCID: PMC4700970 DOI: 10.1371/journal.pbio.1002354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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25
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Terasaki M, Shemesh T, Kasthuri N, Klemm RW, Schalek R, Hayworth KJ, Hand AR, Yankova M, Huber G, Lichtman JW, Rapoport TA, Kozlov MM. Stacked endoplasmic reticulum sheets are connected by helicoidal membrane motifs. Cell 2013; 154:285-96. [PMID: 23870120 PMCID: PMC3767119 DOI: 10.1016/j.cell.2013.06.031] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 04/25/2013] [Accepted: 06/20/2013] [Indexed: 12/28/2022]
Abstract
The endoplasmic reticulum (ER) often forms stacked membrane sheets, an arrangement that is likely required to accommodate a maximum of membrane-bound polysomes for secretory protein synthesis. How sheets are stacked is unknown. Here, we used improved staining and automated ultrathin sectioning electron microscopy methods to analyze stacked ER sheets in neuronal cells and secretory salivary gland cells of mice. Our results show that stacked ER sheets form a continuous membrane system in which the sheets are connected by twisted membrane surfaces with helical edges of left- or right-handedness. The three-dimensional structure of tightly stacked ER sheets resembles a parking garage, in which the different levels are connected by helicoidal ramps. A theoretical model explains the experimental observations and indicates that the structure corresponds to a minimum of elastic energy of sheet edges and surfaces. The structure allows the dense packing of ER sheets in the restricted space of a cell.
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Affiliation(s)
- Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
- Correspondence: (M.T.), (T.A.R.)
| | - Tom Shemesh
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Narayanan Kasthuri
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Robin W. Klemm
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Richard Schalek
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Kenneth J. Hayworth
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Arthur R. Hand
- Departments of Craniofacial Sciences and Cell Biology, University of Connecticut School of Dental Medicine, Farmington, CT 06032, USA
| | - Maya Yankova
- Central Electron Microscopy Facility, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Greg Huber
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
- Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara, CA 93106-4030
| | - Jeff W. Lichtman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Tom A. Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
- Correspondence: (M.T.), (T.A.R.)
| | - Michael M. Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel
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26
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Abstract
FGFs act in vertebrate mesoderm induction and also play key roles in early mesoderm formation in ascidians and amphioxus. However, in sea urchins initial characterizations of FGF function do not support a role in early mesoderm induction, making the ancestral roles of FGF signaling and mechanisms of mesoderm specification in deuterostomes unclear. In order to better characterize the evolution of mesoderm formation, we have examined the role of FGF signaling during mesoderm development in Saccoglossus kowalevskii, an experimentally tractable representative of hemichordates. We report the expression of an FGF ligand, fgf8/17/18, in ectoderm overlying sites of mesoderm specification within the archenteron endomesoderm. Embryological experiments demonstrate that mesoderm induction in the archenteron requires contact with ectoderm, and loss-of-function experiments indicate that both FGF ligand and receptor are necessary for mesoderm specification. fgf8/17/18 gain-of-function experiments establish that FGF8/17/18 is sufficient to induce mesoderm in adjacent endomesoderm. These experiments suggest that FGF signaling is necessary from the earliest stages of mesoderm specification and is required for all mesoderm development. Furthermore, they suggest that the archenteron is competent to form mesoderm or endoderm, and that FGF signaling from the ectoderm defines the location and amount of mesoderm. When considered in a comparative context, these data support a phylogenetically broad requirement for FGF8/17/18 signaling in mesoderm specification and suggest that FGF signaling played an ancestral role in deuterostome mesoderm formation.
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Affiliation(s)
- Stephen A Green
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.
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Shih CS, Ekoma S, Ho C, Pradhan K, Hwang E, Jakacki R, Fisher M, Kilburn L, Horn M, Vezina G, Rood B, Packer R, Mittal R, Omar S, Khalifa N, Bedir R, Avery R, Hwang E, Acosta M, Hutcheson K, Santos D, Zand D, Kilburn L, Rosenbaum K, Rood B, Packer R, Kalin-Hajdu E, Ospina L, Carret AS, Marzouki M, Decarie JC, Freeman E, Hershon L, Warmuth-Metz M, Zurakowski D, Bison B, Falkenstein F, Gnekow A, Ehrstedt C, Laurencikas E, Bjorklund AC, Stromberg B, Hedborg F, Pfeifer S, Bertin D, Packer RJ, Vallero S, Basso ME, Romano E, Peretta P, Morra I, D'Alonzo G, Fagioli F, Toledano H, Laviv Y, Dratviman-Storobinsky O, Michowiz S, Yaniv I, Cohen IJ, Goldenberg-Cohen N, Muller K, Gnekow A, Warmuth-Metz M, Pietsch T, Zwiener I, Falkenstein F, Meyer FM, Micke O, Hoffmann W, Kortmann RD, Shofty B, Ben-Sira L, Roth J, Constantini S, Shofty B, Weizmann L, Joskowicz L, Kesler A, Ben-Bashat D, Yalon M, Dvir R, Freedman S, Roth J, Ben-Sira L, Constantini S, Bandopadhayay P, Dagi L, Robison N, Goumnerova L, Ullrich N, Opocher E, De Salvo GL, De Paoli A, Simmons I, Sehested A, Walker DA, Picton SV, Gnekow A, Grill J, Driever PH, Azizi AA, Viscardi E, Perilongo G, Cappellano AM, Bouffet E, Silva F, Paiva P, Cavalheiro S, Seixas MT, Silva NS, Antony R, Fraser K, Lin J, Falkenstein F, Kwiecien R, Mirow C, Thieme B, von Hornstein S, Pietsch T, Faldum A, Warmuth-Metz M, Kortmann RD, Gnekow AK, Shofty B, Bokshtein F, Kesler A, Ben-Sira L, Freedman S, Constantini S, Panandiker AP, Klimo P, Thompson C, Armstrong G, Kun L, Boop F, Sanford A, Orge F, Laschinger K, Gold D, Bangert B, Stearns D, Cappellano AM, Senerchia A, Paiva P, Cavalheiro S, Silva F, Silva NS, Gnekow AK, Falkenstein F, Walker D, Perilongo G, Picton S, Grill J, Kortmann RD, Stokland T, van Meeteren AS, Slavc I, Faldum A, de Salvo GL, Fernandez KS, Antony R, Lulla RR, Flores M, Benavides VC, Mitchell C, AlKofide A, Hassonah M, Khafagh Y, Ayas MA, AlFawaz I, Anas M, Barria M, Siddiqui K, Al-Shail E, Fisher MJ, Ullrich NJ, Ferner RE, Gutmann DH, Listernick R, Packer RJ, Tabori U, Hoffman RO, Ardern-Holmes SL, Hummel TR, Hargrave DR, Charrow J, Loguidice M, Balcer LJ, Liu GT, Fisher MJ, Listernick R, Gutmann DH, Ferner RE, Packer RJ, Ullrich NJ, Tabori U, Hoffman RO, Ardern-Holmes SL, Hummel TR, Hargrave DR, Loguidice M, Balcer LJ, Liu GT, Jeeva I, Nelson O, Guy D, Damani A, Gogi D, Picton S, Simmons I, Jeeva I, Picton S, Guy D, Nelson O, Dewsbery S, Gogi D, Simmons I, Sievert AJ, Lang SS, Boucher K, Slaunwhite E, Brewington D, Madsen P, Storm PB, Resnick AC, Hemenway M, Madden J, Macy M, Foreman N, Rush S, Mascelli S, Raso A, Barla A, Nozza P, Biassoni R, Pignatelli S, Cama A, Verri A, Capra V, Garre M, Bergthold G, Piette C, Raquin MA, Dufour C, Varlet P, Dhermain F, Puget S, Sainte-Rose C, Abely M, Canale S, Grill J, Terashima K, Chow K, Jones J, Ahern C, Jo E, Ellezam B, Paulino A, Okcu MF, Su J, Adesina A, Mahajan A, Dauser R, Whitehead W, Lau C, Chintagumpala M, Kebudi R, Tuncer S, Cakir FB, Gorgun O, Agaoglu FY, Ayan I, Darendeliler E, Wolf D, Cohen K, Jeyapalan JN, Morley ICF, Hill AA, Tatevossian RG, Qaddoumi I, Ellison DW, Sheer D, Donson A, Barton V, Birks D, Kleinschmidt-DeMasters BK, Hemenway M, Handler M, Foreman N, Rush S, Tatevossian R, Qaddoumi I, Tang B, Dalton J, Shurtleff S, Punchihewa C, Orisme W, Neale G, Gajjar A, Baker S, Sheer D, Ellison D, Gilheeney S, Jamzadeh A, Winchester M, Yataghene K, De Braganca K, Khakoo Y, Lyden D, Dunkel I, Terasaki M, Eto T, Morioka M, Ho CY, Bar E, Giannini C, Karajannis MA, Zagzag D, Eberhart CG, Rodriguez FJ, Lee Y, Bartels U, Tabori U, Huang A, Bouffet E, Zaky W, Bluml S, Grimm J, Wong K, McComb G, Gilles F, Finlay J, Dhall G, Chen HH, Chen YW, Chang FC, Lin SC, Chang KP, Ho DM, Wong TT, Lee CC, Azizi AA, Fox R, Grill J, Mirow C, Gnekow A, Walker D, Perilongo G, Opocher E, Wheatley K, van Meeteren AYS, Phuakpet K, Tabori U, Bartels U, Huang A, Kulkarni A, Laperriere N, Bouffet E, Epari S, Nair V, Gupta T, Patil P, Moiyadi A, Shetty P, Kane S, Jalali R, Dorris K, Nadi M, Sutton M, Wang L, Stogner K, Li D, Hurwitz B, Stevenson C, Miles L, Kim MO, Fuller C, Hawkins C, Bouffet E, Jones B, Drake J, Fouladi M, Fontebasso AM, Shirinian M, Jones DTW, Quang DAK, Jacob K, Cin H, Witt H, Gerges N, Montpetit A, Brunet S, Lepage P, Klekner A, Lambert S, Kwan T, Hawkins C, Tabori U, Collins VP, Albrecht S, Pfister SM, Jabado N, Arrington D, Manley P, Kieran M, Chi S, Robison N, Chordas C, Ullrich N. LOW GRADE GLIOMAS. Neuro Oncol 2012; 14:i69-i81. [PMCID: PMC3483338 DOI: 10.1093/neuonc/nos092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
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Nagashima M, Watanabe T, Terasaki M, Tomoyasu M, Nohtomi K, Kim-Kaneyama J, Miyazaki A, Hirano T. Native incretins prevent the development of atherosclerotic lesions in apolipoprotein E knockout mice. Diabetologia 2011; 54:2649-59. [PMID: 21786155 PMCID: PMC3168747 DOI: 10.1007/s00125-011-2241-2] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 05/31/2011] [Indexed: 01/15/2023]
Abstract
AIMS/HYPOTHESIS Several lines of evidence suggest that incretin-based therapies suppress the development of cardiovascular disease in type 2 diabetes. We investigated the possibility that glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) can prevent the development of atherosclerosis in Apoe (-/-) mice. METHODS Apoe (-/-) mice (17 weeks old) were administered GLP-1(7-36)amide, GLP-1(9-36)amide, GIP(1-42) or GIP(3-42) for 4 weeks. Aortic atherosclerosis, oxidised LDL-induced foam cell formation and related gene expression in exudate peritoneal macrophages were determined. RESULTS Administration of GLP-1(7-36)amide or GIP(1-42) significantly suppressed atherosclerotic lesions and macrophage infiltration in the aortic wall, compared with vehicle controls. These effects were cancelled by co-infusion with specific antagonists for GLP-1 and GIP receptors, namely exendin(9-39) or Pro(3)(GIP). The anti-atherosclerotic effects of GLP-1(7-36)amide and GIP(1-42) were associated with significant decreases in foam cell formation and downregulation of CD36 and acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) in macrophages. GLP-1 and GIP receptors were both detected in Apoe (-/-) mouse macrophages. Ex vivo incubation of macrophages with GLP-1(7-36)amide or GIP(1-42) for 48 h significantly suppressed foam cell formation. This effect was wholly abolished in macrophages pretreated with exendin(9-39) or (Pro(3))GIP, or with an adenylate cyclase inhibitor, MDL12,330A, and was mimicked by incubation with an adenylate cyclase activator, forskolin. The inactive forms, GLP-1(9-36)amide and GIP(3-42), had no effects on atherosclerosis and macrophage foam cell formation. CONCLUSIONS/INTERPRETATION Our study is the first to demonstrate that active forms of GLP-1 and GIP exert anti-atherogenic effects by suppressing macrophage foam cell formation via their own receptors, followed by cAMP activation. Molecular mechanisms underlying these effects are associated with the downregulation of CD36 and ACAT-1 by incretins.
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Affiliation(s)
- M. Nagashima
- Department of Medicine, Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8666 Japan
| | - T. Watanabe
- Laboratory of Cardiovascular Medicine, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - M. Terasaki
- Department of Medicine, Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8666 Japan
| | - M. Tomoyasu
- Department of Medicine, Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8666 Japan
| | - K. Nohtomi
- Department of Medicine, Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8666 Japan
| | - J. Kim-Kaneyama
- Department of Biochemistry, Showa University School of Medicine, Tokyo, Japan
| | - A. Miyazaki
- Department of Biochemistry, Showa University School of Medicine, Tokyo, Japan
| | - T. Hirano
- Department of Medicine, Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8666 Japan
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Darras S, Gerhart J, Terasaki M, Kirschner M, Lowe CJ. β-catenin specifies the endomesoderm and defines the posterior organizer of the hemichordate Saccoglossus kowalevskii. Development 2011; 138:959-70. [PMID: 21303849 DOI: 10.1242/dev.059493] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The canonical Wnt/β-catenin pathway is a key regulator of body plan organization and axis formation in metazoans, being involved in germ layer specification, posterior growth and patterning of the anteroposterior axis. Results from animals spanning a wide phylogenetic range suggest that a unifying function of β-catenin in metazoans is to define the posterior/vegetal part of the embryo. Although the specification of vegetal territories (endoderm) by β-catenin has been demonstrated in distantly related animals (cnidarians, a protostome, echinoderms and ascidians), the definition of the posterior part of the embryo is well supported only for vertebrates and planarians. To gain insights into β-catenin functions during deuterostome evolution, we have studied the early development of the direct developing hemichordate Saccoglossus kowalevskii. We show that the zygote is polarized after fertilization along the animal-vegetal axis by cytoplasmic rearrangements resembling the ascidian vegetal contraction. This early asymmetry is translated into nuclear accumulation of β-catenin at the vegetal pole, which is necessary and sufficient to specify endomesoderm. We show that endomesoderm specification is crucial for anteroposterior axis establishment in the ectoderm. The endomesoderm secretes as yet unidentified signals that posteriorize the ectoderm, which would otherwise adopt an anterior fate. Our results point to a conserved function at the base of deuterostomes for β-catenin in germ layer specification and to a causal link in the definition of the posterior part of the embryonic ectoderm by way of activating posteriorizing endomesodermal factors. Consequently, the definition of the vegetal and the posterior regions of the embryo by β-catenin should be distinguished and carefully re-examined.
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Affiliation(s)
- Sébastien Darras
- Institut de Biologie du Développement de Marseille-Luminy, UMR 6216, CNRS, Université de la Méditerranée, Campus de Luminy, Marseille Cedex 09, France.
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Terasaki M, Runft L. Two-stage dependence for 1-methyladenine induced reinitiation of meiotic maturation in starfish oocytes. Exp Cell Res 2010; 316:2654-63. [DOI: 10.1016/j.yexcr.2010.05.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 05/07/2010] [Accepted: 05/27/2010] [Indexed: 10/19/2022]
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Terasaki M, Noguchi M, Naito S, Uemura H, Akaza H, Sibui S, Fujimaki T, Aoki T, Itoh K. Phase I trial of personalized peptide vaccine for HLA-A24 positive patients with advanced cancer. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.3079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Terasaki M, Loew L, Lippincott-Schwartz J, Zaal K. Fluorescent staining of subcellular organelles: ER, Golgi complex, and mitochondria. ACTA ACUST UNITED AC 2008; Chapter 4:Unit 4.4. [PMID: 18228364 DOI: 10.1002/0471143030.cb0404s00] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The ability to distinguish and identify specific subcellular compartments is essential to understanding organelle function, biogenesis, and maintenance within cells and to defining protein trafficking pathways. Fluorescent dyes and/or fluorescently labeled lipid derivatives can be used to identify ER, Golgi complex, and mitochondria. Specific conditions for labeling each of these compartments are described.
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Affiliation(s)
- M Terasaki
- University of Connecticut Health Center, Farmington, Connecticut, USA
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Lowe CJ, Terasaki M, Wu M, Freeman RM, Runft L, Kwan K, Haigo S, Aronowicz J, Lander E, Gruber C, Smith M, Kirschner M, Gerhart J. Dorsoventral patterning in hemichordates: insights into early chordate evolution. PLoS Biol 2006; 4:e291. [PMID: 16933975 PMCID: PMC1551926 DOI: 10.1371/journal.pbio.0040291] [Citation(s) in RCA: 302] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 06/28/2006] [Indexed: 11/19/2022] Open
Abstract
We have compared the dorsoventral development of hemichordates and chordates to deduce the organization of their common ancestor, and hence to identify the evolutionary modifications of the chordate body axis after the lineages split. In the hemichordate embryo, genes encoding bone morphogenetic proteins (Bmp) 2/4 and 5/8, as well as several genes for modulators of Bmp activity, are expressed in a thin stripe of ectoderm on one midline, historically called "dorsal." On the opposite midline, the genes encoding Chordin and Anti-dorsalizing morphogenetic protein (Admp) are expressed. Thus, we find a Bmp-Chordin developmental axis preceding and underlying the anatomical dorsoventral axis of hemichordates, adding to the evidence from Drosophila and chordates that this axis may be at least as ancient as the first bilateral animals. Numerous genes encoding transcription factors and signaling ligands are expressed in the three germ layers of hemichordate embryos in distinct dorsoventral domains, such as pox neuro, pituitary homeobox, distalless, and tbx2/3 on the Bmp side and netrin, mnx, mox, and single-minded on the Chordin-Admp side. When we expose the embryo to excess Bmp protein, or when we deplete endogenous Bmp by small interfering RNA injections, these expression domains expand or contract, reflecting their activation or repression by Bmp, and the embryos develop as dorsalized or ventralized limit forms. Dorsoventral patterning is independent of anterior/posterior patterning, as in Drosophila but not chordates. Unlike both chordates and Drosophila, neural gene expression in hemichordates is not repressed by high Bmp levels, consistent with their development of a diffuse rather than centralized nervous system. We suggest that the common ancestor of hemichordates and chordates did not use its Bmp-Chordin axis to segregate epidermal and neural ectoderm but to pattern many other dorsoventral aspects of the germ layers, including neural cell fates within a diffuse nervous system. Accordingly, centralization was added in the chordate line by neural-epidermal segregation, mediated by the pre-existing Bmp-Chordin axis. Finally, since hemichordates develop the mouth on the non-Bmp side, like arthropods but opposite to chordates, the mouth and Bmp-Chordin axis may have rearranged in the chordate line, one relative to the other.
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Affiliation(s)
- Christopher J Lowe
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, United States of America
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Michael Wu
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, United States of America
| | - Robert M Freeman
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Linda Runft
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Kristen Kwan
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Saori Haigo
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jochanan Aronowicz
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, United States of America
| | - Eric Lander
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Chris Gruber
- Express Genomics, Frederick, Maryland, United States of America
| | - Mark Smith
- Express Genomics, Frederick, Maryland, United States of America
| | - Marc Kirschner
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - John Gerhart
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, United States of America
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Takeya M, Terasaki M, Terasaki Y, Sakashita N, Sato H. We-P12:288 Induction of macrophage receptor with collagenous structure (MARCO) suggests possible involvement of endotoxin in nonalcoholic steatohepatitis (NASH). ATHEROSCLEROSIS SUPP 2006. [DOI: 10.1016/s1567-5688(06)81641-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Terasaki M, Uchikado H, Takeuchi Y, Shigemori M. Minimally Invasive Management of Ependymoma of the Aqueduct of Sylvius: Therapeutic Considerations and Management. ACTA ACUST UNITED AC 2005; 48:322-4. [PMID: 16432779 DOI: 10.1055/s-2005-915628] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A major concern in the neuroendoscopic approach to an intraventricular tumor is the histological confirmation from a limited biopsy. However, the effort to excise the whole bulk of the tumor should be made for the minimally invasive management of selected intraventricular tumors. The case of an adult male with focal aqueductal ependymoma who presented with the clinical syndrome of hydrocephalus is reported. This may be of particular interest because it represents the first case of aqueductal ependymoma that has been successfully treated with endoscopic surgery.
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Affiliation(s)
- M Terasaki
- Department of Neurosurgery, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
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Abstract
Plasma membrane wound repair is an important but poorly understood process. We used femtosecond pulses from a Ti-Sapphire laser to make multiphoton excitation–induced disruptions of the plasma membrane while monitoring the membrane potential and resistance. We observed two types of wounds that depolarized the plasma membrane. At threshold light levels, the membrane potential and resistance returned to prewound values within seconds; these wounds were not easily observed by light microscopy and resealed in the absence of extracellular Ca2+. Higher light intensities create wounds that are easily visible by light microscopy and require extracellular Ca2+ to reseal. Within a few seconds the membrane resistance is ∼100-fold lower, while the membrane potential has depolarized from −80 to −30 mV and is now sensitive to the Cl− concentration but not to that of Na+, K+, or H+. We suggest that the chloride sensitivity of the membrane potential, after wound resealing, is due to the fusion of chloride-permeable intracellular membranes with the plasma membrane.
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Affiliation(s)
- Alan Fein
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
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Abstract
BACKGROUND INFORMATION Fluorescence imaging of living cells is widely used in cell biology. It is now being extended to thick specimens such as large cells or tissues where it is important to establish methods for obtaining quantitative fluorescence data due to the increasing importance of computational and systems biology approaches. RESULTS Fluorescent solutions were used as a calibration standard for determining cellular fluorescence concentrations from z series image sequences. The accuracy of the measurements was evaluated using quantitatively injected cells. Different fluorescence attenuation rates of the cytoplasm and nucleoplasm were documented, and autofluorescence levels were determined. This method was used to characterize the effect of cyclin B overexpression on cell-cycle timing in starfish oocytes. The time interval between application of maturation hormone and germinal vesicle breakdown decreased with increasing cyclin B-GFP (green fluorescent protein) concentration to a level of 100-300 nM, beyond which there was no effect. CONCLUSIONS Conditions for determining fluorescent probe concentrations in large cells or multicellular tissues were established, which will facilitate the collection of data for quantitative studies. This method was used to characterize the effect of cyclin B-GFP expression levels on cell-cycle timing in starfish oocytes.
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Affiliation(s)
- Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06032, USA.
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Lénárt P, Bacher CP, Daigle N, Hand AR, Eils R, Terasaki M, Ellenberg J. A contractile nuclear actin network drives chromosome congression in oocytes. Nature 2005; 436:812-8. [PMID: 16015286 DOI: 10.1038/nature03810] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Accepted: 05/03/2005] [Indexed: 11/09/2022]
Abstract
Chromosome capture by microtubules is widely accepted as the universal mechanism of spindle assembly in dividing cells. However, the observed length of spindle microtubules and computer simulations of spindle assembly predict that chromosome capture is efficient in small cells, but may fail in cells with large nuclear volumes such as animal oocytes. Here we investigate chromosome congression during the first meiotic division in starfish oocytes. We show that microtubules are not sufficient for capturing chromosomes. Instead, chromosome congression requires actin polymerization. After nuclear envelope breakdown, we observe the formation of a filamentous actin mesh in the nuclear region, and find that contraction of this network delivers chromosomes to the microtubule spindle. We show that this mechanism is essential for preventing chromosome loss and aneuploidy of the egg--a leading cause of pregnancy loss and birth defects in humans.
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Affiliation(s)
- Péter Lénárt
- Gene Expression and Cell Biology/Biophysics Programmes, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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Abstract
Second harmonic generation offers an important alternative and complement to fluorescence for the imaging of cellular structure and function. Staining the eggs of the sea urchin, Lytechinus pictus, with the styryl dye di-8-ANEPPS, we have observed large changes in both second harmonic generation and two-photon fluorescence after fertilization, consistent with the dynamics of exocytosis of cortical granules. With nonlinear imaging on a scanning microscope, we are able to visualize the wave of exocytosis in real time.
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Affiliation(s)
- Andrew C Millard
- Department of Cell Biology, University of Connecticut Health Center, Farmington, 06030-1507, USA
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Basu S, Rodionov V, Terasaki M, Campagnola PJ. Multiphoton-excited microfabrication in live cells via Rose Bengal cross-linking of cytoplasmic proteins. Opt Lett 2005; 30:159-161. [PMID: 15675699 DOI: 10.1364/ol.30.000159] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We demonstrate the use of multiphoton-excited photochemistry to cross-link three-dimensional matrices directly from cytoplasmic proteins in a live cell (starfish oocyte). Fluorescence recovery after photobleaching measurements were used to determine diffusion coefficients inside intracellular cross-linked structures, and it was found that the diffusion was approximately 3 to 4 orders of magnitude slower than in free solution and 2-3 orders of magnitude slower than in cytoplasm and that the value can be tuned by controlling the laser exposure. Complex structures can be fabricated to construct channels and compartments that could be used to isolate cellular processes, and the method should thus be applicable to a broad range of problems in cell biology.
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Affiliation(s)
- Swarna Basu
- University of Connecticut Health Center, Department of Cell Biology, Farmington, Connecticut 06030, USA
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Morris RL, English CN, Lou JE, Dufort FJ, Nordberg J, Terasaki M, Hinkle B. Redistribution of the kinesin-II subunit KAP from cilia to nuclei during the mitotic and ciliogenic cycles in sea urchin embryos. Dev Biol 2004; 274:56-69. [PMID: 15355788 DOI: 10.1016/j.ydbio.2004.06.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Revised: 06/17/2004] [Accepted: 06/18/2004] [Indexed: 11/25/2022]
Abstract
KAP is the non-motor subunit of the heteromeric plus-end directed microtubule (MT) motor protein kinesin-II essential for normal cilia formation. Studies in Chlamydomonas have demonstrated that kinesin-II drives the anterograde intraflagellar transport (IFT) of protein complexes along ciliary axonemes. We used a green fluorescent protein (GFP) chimera of KAP, KAP-GFP, to monitor movements of this kinesin-II subunit in cells of sea urchin blastulae where cilia are retracted and rebuilt with each mitosis. As expected if involved in IFT, KAP-GFP localized to apical cytoplasm, basal bodies, and cilia and became concentrated on basal bodies of newly forming cilia. Surprisingly, after ciliary retraction early in mitosis, KAP-GFP moved into nuclei before nuclear envelope breakdown, was again present in nuclei after nuclear envelope reformation, and only decreased in nuclei as ciliogenesis reinitiated. Nuclear transport of KAP-GFP could be due to a putative nuclear localization signal and nuclear export signals identified in the sea urchin KAP primary sequence. Our observation of a protein involved in IFT being imported into the nucleus after ciliary retraction and again after nuclear envelope reformation suggests KAP115 may serve as a signal to the nucleus to reinitiate cilia formation during sea urchin development.
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Affiliation(s)
- Robert L Morris
- Department of Biology, Wheaton College, Norton, MA 02766, USA.
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Abstract
Ideas of how a system of interacting enzymes can act as a switch are based on the concept of bistability of a biochemical network. This means that, because of the very structure of a signaling pathway, the system can be in one of two stable steady states: active or inactive. Switching from one state to another may then occur in response to external stimuli or as a result of internal development. However, the bistability of a biochemical network might not be robust enough to be the sole mechanism behind bio-switching. On the basis of recent experimental data on the cell-cycle G2/M transition during starfish oocyte meiotic maturation, it is shown that cooperative phenomena--such as phase changes associated with clustering, dissolution of aggregates and so on--may play central roles in providing a decisive and irreversible transition.
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Affiliation(s)
- Boris M Slepchenko
- Department of Cell Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, Connecticut 06030-1507, USA.
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44
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Affiliation(s)
- Laurinda A Jaffe
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06032, USA
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45
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Affiliation(s)
- Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06032, USA
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46
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Abstract
The Cdc2-cyclin B kinase has a central role in regulating the onset of M phase. In starfish oocytes, Cdc2-cyclin B begins to be activated approximately 10 min after application of maturation hormone, followed by accumulation in the nucleus then nuclear envelope breakdown. By immunofluorescence and by expressing a green fluorescent (GFP) chimera of cyclin B, we find that cyclin B is present in aggregates in the cytoplasm of immature oocytes. The aggregates disperse at approximately 10 min, suggesting that the dispersal is closely related to the activation of the kinase. Using cyclin B-GFP, the dispersion begins from the region containing the centrosomes. Extractability of Cdc2-cyclin B changes with similar kinetics during maturation. Active Cdc25 phosphatase released Cdc2-cyclin B from the detergent-insoluble fraction independently of its phosphatase activity. Live cell imaging also showed that Cdc2-cyclin B begins to accumulate in the nucleus before changes in nuclear pore permeability, consistent with Cdc2-cyclin B-induced disassembly of the pores.
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Affiliation(s)
- Mark Terasaki
- Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06032, USA.
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47
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Abstract
During the cell cycle, Cdc2-cyclin B kinase abruptly becomes active and triggers the entry into mitosis/meiosis. Recently, it was found that inactive Cdc2-cyclin B is present in aggregates in immature starfish oocytes and becomes disaggregated at the time of its activation during maturation. We discuss a possible scenario in which aggregation of Cdc2-cyclin B dramatically enhances robustness of this activation. In this scenario, only inactive Cdc2-cyclin B can form aggregates, and the aggregates are in equilibrium with inactive Cdc2-cyclin B in solution. During maturation, the hormone-triggered inactivation of Myt1 depletes the soluble inactive Cdc2-cyclin B and the turnover leads to dissolution of the aggregates. This phase change, when coupled with the instability of the signaling network, provides a robust bio-switch.
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Affiliation(s)
- Boris M Slepchenko
- Center for Biomedical Imaging Technology, Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06032, USA.
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48
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Galbraith JA, Terasaki M. Controlled damage in thick specimens by multiphoton excitation. Mol Biol Cell 2003; 14:1808-17. [PMID: 12802057 PMCID: PMC165079 DOI: 10.1091/mbc.e02-03-0163] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2002] [Revised: 12/09/2002] [Accepted: 12/27/2002] [Indexed: 11/11/2022] Open
Abstract
Controlled damage by light energy has been a valuable tool in studies of cell function. Here, we show that the Ti:Sapphire laser in a multiphoton microscope can be used to cause localized damage within unlabeled cells or tissues at greater depths than previously possible. We show that the damage is due to a multiphoton process and made wounds as small as 1 microm in diameter 20 microm from the surface. A characteristic fluorescent scar allows monitoring of the damage and identifies the wound site in later observations. We were able to lesion a single axon within a bundle of nerves, locally interrupt organelle transport within one axon, cut dendrites in a zebrafish embryo, ablate a mitotic pole in a sea urchin egg, and wound the plasma membrane and nuclear envelope in starfish oocytes. The starfish nucleus collapsed approximately 1 h after wounding, indicating that loss of compartmentation barrier makes the structure unstable; surprisingly, the oocyte still completed meiotic divisions when exposed to maturation hormone, indicating that the compartmentalization and translocation of cdk1 and its regulators is not required for this process. Multiphoton excitation provides a new means for producing controlled damage deep within tissues or living organisms.
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Affiliation(s)
- James A Galbraith
- Laboratory of Neurobiology, NINDS, National Institutes of Health, Bethesda, Maryland 20892, USA
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49
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Lénárt P, Rabut G, Daigle N, Hand AR, Terasaki M, Ellenberg J. Nuclear envelope breakdown in starfish oocytes proceeds by partial NPC disassembly followed by a rapidly spreading fenestration of nuclear membranes. J Cell Biol 2003; 160:1055-68. [PMID: 12654902 PMCID: PMC2172766 DOI: 10.1083/jcb.200211076] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2002] [Revised: 02/07/2003] [Accepted: 02/14/2003] [Indexed: 11/22/2022] Open
Abstract
Breakdown of the nuclear envelope (NE) was analyzed in live starfish oocytes using a size series of fluorescently labeled dextrans, membrane dyes, and GFP-tagged proteins of the nuclear pore complex (NPC) and the nuclear lamina. Permeabilization of the nucleus occurred in two sequential phases. In phase I the NE became increasingly permeable for molecules up to approximately 40 nm in diameter, concurrent with a loss of peripheral nuclear pore components over a time course of 10 min. The NE remained intact on the ultrastructural level during this time. In phase II the NE was completely permeabilized within 35 s. This rapid permeabilization spread as a wave from one epicenter on the animal half across the nuclear surface and allowed free diffusion of particles up to approximately 100 nm in diameter into the nucleus. While the lamina and nuclear membranes appeared intact at the light microscopic level, a fenestration of the NE was clearly visible by electron microscopy in phase II. We conclude that NE breakdown in starfish oocytes is triggered by slow sequential disassembly of the NPCs followed by a rapidly spreading fenestration of the NE caused by the removal of nuclear pores from nuclear membranes still attached to the lamina.
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Affiliation(s)
- Péter Lénárt
- Gene Expression and Cell Biology/Biophysics Programmes, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
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50
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Hinkle B, Slepchenko B, Rolls MM, Walther TC, Stein PA, Mehlmann LM, Ellenberg J, Terasaki M. Chromosomal association of Ran during meiotic and mitotic divisions. J Cell Sci 2002; 115:4685-93. [PMID: 12415012 DOI: 10.1242/jcs.00136] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Recent studies in Xenopus egg extracts indicate that the small G protein Ran has a central role in spindle assembly and nuclear envelope reformation. We determined Ran localization and dynamics in cells during M phase. By immunofluorescence, Ran is accumulated on the chromosomes of meiosis-II-arrested Xenopus eggs. In living cells, fluorescently labeled Ran associated with the chromosomes in Xenopus and remained associated during anaphase when eggs were artificially activated. Fluorescent Ran associated with chromosomes in mouse eggs, during meiotic maturation and early embryonic divisions in starfish, and to a lesser degree during mitosis of a cultured mammalian cell line. Chromosomal Ran undergoes constant flux. From photobleach experiments in immature starfish oocytes, chromosomal Ran has a k(off) of approximately 0.06 second(-1), and binding analysis suggests that there is a single major site. The chromosomal interactions may serve to keep Ran-GTP in the vicinity of the chromosomes for spindle assembly and nuclear envelope reformation.
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Affiliation(s)
- Beth Hinkle
- Department of Physiology, University of Connecticut Health Center, Farmington, CT 06032, USA
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