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Zeng Y, Plachetzki DC, Nieders K, Campbell H, Cartee M, Pankey MS, Guillen K, Fudge D. Epidermal threads reveal the origin of hagfish slime. eLife 2023; 12:81405. [PMID: 36897815 PMCID: PMC10005773 DOI: 10.7554/elife.81405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 01/22/2023] [Indexed: 03/11/2023] Open
Abstract
When attacked, hagfishes produce a soft, fibrous defensive slime within a fraction of a second by ejecting mucus and threads into seawater. The rapid setup and remarkable expansion of the slime make it a highly effective and unique form of defense. How this biomaterial evolved is unknown, although circumstantial evidence points to the epidermis as the origin of the thread- and mucus-producing cells in the slime glands. Here, we describe large intracellular threads within a putatively homologous cell type from hagfish epidermis. These epidermal threads averaged ~2 mm in length and ~0.5 μm in diameter. The entire hagfish body is covered by a dense layer of epidermal thread cells, with each square millimeter of skin storing a total of ~96 cm threads. Experimentally induced damage to a hagfish's skin caused the release of threads, which together with mucus, formed an adhesive epidermal slime that is more fibrous and less dilute than the defensive slime. Transcriptome analysis further suggests that epidermal threads are ancestral to the slime threads, with duplication and diversification of thread genes occurring in parallel with the evolution of slime glands. Our results support an epidermal origin of hagfish slime, which may have been driven by selection for stronger and more voluminous slime.
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Affiliation(s)
- Yu Zeng
- Schmid College of Science and Technology, Chapman University, Orange, United States
| | - David C Plachetzki
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Kristen Nieders
- Schmid College of Science and Technology, Chapman University, Orange, United States
| | - Hannah Campbell
- Schmid College of Science and Technology, Chapman University, Orange, United States
| | - Marissa Cartee
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States.,Department of Evolution, Ecology and Organismal Biology, University of California at Riverside, Riverside, United States
| | - M Sabrina Pankey
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Kennedy Guillen
- Schmid College of Science and Technology, Chapman University, Orange, United States
| | - Douglas Fudge
- Schmid College of Science and Technology, Chapman University, Orange, United States
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Yenmiş M, Ayaz D. The Story of the Finest Armor: Developmental Aspects of Reptile Skin. J Dev Biol 2023; 11:jdb11010005. [PMID: 36810457 PMCID: PMC9944452 DOI: 10.3390/jdb11010005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/06/2023] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
The reptile skin is a barrier against water loss and pathogens and an armor for mechanical damages. The integument of reptiles consists of two main layers: the epidermis and the dermis. The epidermis, the hard cover of the body which has an armor-like role, varies among extant reptiles in terms of structural aspects such as thickness, hardness or the kinds of appendages it constitutes. The reptile epithelial cells of the epidermis (keratinocytes) are composed of two main proteins: intermediate filament keratins (IFKs) and corneous beta proteins (CBPs). The outer horny layer of the epidermis, stratum corneum, is constituted of keratinocytes by means of terminal differentiation or cornification which is a result of the protein interactions where CBPs associate with and coat the initial scaffold of IFKs. Reptiles were able to colonize the terrestrial environment due to the changes in these epidermal structures, which led to various cornified epidermal appendages such as scales and scutes, a beak, claws or setae. Developmental and structural aspects of the epidermal CBPs as well as their shared chromosomal locus (EDC) indicate an ancestral origin that gave rise to the finest armor of reptilians.
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Bressman N, Fudge D. From reductionism to synthesis: The case of hagfish slime. Comp Biochem Physiol B Biochem Mol Biol 2021; 255:110610. [PMID: 33971350 DOI: 10.1016/j.cbpb.2021.110610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/28/2021] [Accepted: 05/04/2021] [Indexed: 11/17/2022]
Abstract
Reductionist strategies aim to understand the mechanisms of complex systems by studying individual parts and their interactions. In this review, we discuss how reductionist approaches have shed light on the structure, function, and production of a complex biomaterial - hagfish defensive slime. Hagfish slime is an extremely dilute hydrogel-like material composed of seawater, mucus, and silk-like proteins that can deploy rapidly. Despite being composed almost entirely of water, hagfish slime has remarkable physical properties, including high strength and toughness. While hagfish slime has a promising future in biomimetics, including the development of eco-friendly high-performance fibers, recreating hagfish slime in the lab has been a difficult challenge. Over the past two decades, reductionist experiments have provided a wealth of information about the individual components of hagfish slime. However, a reductionist approach provides a limited understanding because hagfish defensive slime, like most biological phenomena, is more than just the sum of its parts. We end by providing some thoughts about how the knowledge generated in the last few decades might be synthesized into a working model that can explain hagfish slime structure and function.
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Affiliation(s)
- Noah Bressman
- Schmid College of Science and Technology, Chapman University, 1 University Dr., Orange, CA 92866, USA.
| | - Douglas Fudge
- Schmid College of Science and Technology, Chapman University, 1 University Dr., Orange, CA 92866, USA
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Kimura Y, Nikaido M. Conserved keratin gene clusters in ancient fish: An evolutionary seed for terrestrial adaptation. Genomics 2020; 113:1120-1128. [PMID: 33189779 DOI: 10.1016/j.ygeno.2020.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/05/2020] [Accepted: 11/09/2020] [Indexed: 11/26/2022]
Abstract
Type I and type II keratins are subgroups of intermediate filament proteins that provide toughness to the epidermis and protect it from water loss. In terrestrial vertebrates, the keratin genes form two major clusters, clusters 1 and 2, each of which is dominated by type I and II keratin genes. By contrast, such clusters are not observed in teleost fish. Although the diversification of keratins is believed to have made a substantial contribution to terrestrial adaptation, its evolutionary process has not been clarified. Here, we performed a comprehensive genomic survey of the keratin genes of a broad range of vertebrates. As a result, we found that ancient fish lineages such as elephant shark, reedfish, spotted gar, and coelacanth share both keratin gene clusters. We also discovered an expansion of keratin genes that form a novel subcluster in reedfish. Syntenic and phylogenetic analyses revealed that two pairs of krt18/krt8 keratin genes were shared among all vertebrates, thus implying that they encode ancestral type I and II keratin protein sets. We further revealed that distinct keratin gene subclusters, which show specific expressions in the epidermis of adult amphibians, stemmed from canonical keratin genes in non-terrestrial ancestors. Molecular evolutionary analyses suggested that the selective constraints were relaxed in the adult epidermal subclusters of amphibians as well as the novel subcluster of reedfish. The results of the present study represent the process of diversification of keratins through a series of gene duplications that could have facilitated the terrestrial adaptation of vertebrates.
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Affiliation(s)
- Yuki Kimura
- School of Life Science and Technology, Tokyo Institute of Technology, Japan
| | - Masato Nikaido
- School of Life Science and Technology, Tokyo Institute of Technology, Japan.
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5
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Cokus SJ, De La Torre M, Medina EF, Rasmussen JP, Ramirez-Gutierrez J, Sagasti A, Wang F. Tissue-Specific Transcriptomes Reveal Gene Expression Trajectories in Two Maturing Skin Epithelial Layers in Zebrafish Embryos. G3 (BETHESDA, MD.) 2019; 9:3439-3452. [PMID: 31431477 PMCID: PMC6778804 DOI: 10.1534/g3.119.400402] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 08/18/2019] [Indexed: 12/19/2022]
Abstract
Epithelial cells are the building blocks of many organs, including skin. The vertebrate skin initially consists of two epithelial layers, the outer periderm and inner basal cell layers, which have distinct properties, functions, and fates. The embryonic periderm ultimately disappears during development, whereas basal cells proliferate to form the mature, stratified epidermis. Although much is known about mechanisms of homeostasis in mature skin, relatively little is known about the two cell types in pre-stratification skin. To define the similarities and distinctions between periderm and basal skin epithelial cells, we purified them from zebrafish at early development stages and deeply profiled their gene expression. These analyses identified groups of genes whose tissue enrichment changed at each stage, defining gene flow dynamics of maturing vertebrate epithelia. At each of 52 and 72 hr post-fertilization (hpf), more than 60% of genes enriched in skin cells were similarly expressed in both layers, indicating that they were common epithelial genes, but many others were enriched in one layer or the other. Both expected and novel genes were enriched in periderm and basal cell layers. Genes encoding extracellular matrix, junctional, cytoskeletal, and signaling proteins were prominent among those distinguishing the two epithelial cell types. In situ hybridization and BAC transgenes confirmed our expression data and provided new tools to study zebrafish skin. Collectively, these data provide a resource for studying common and distinguishing features of maturing epithelia.
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Affiliation(s)
- Shawn J Cokus
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles and
| | | | - Eric F Medina
- Department of Biology, California State University, Dominguez Hills
| | - Jeffrey P Rasmussen
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles and
| | | | - Alvaro Sagasti
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles and
| | - Fang Wang
- Department of Biology, California State University, Dominguez Hills
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Keratinization and mucogenesis in the epidermis of an angler catfish Chaca chaca (Siluriformes, Chacidae): A Histochemical and fluorescence microscope investigation. ZOOLOGY 2018; 131:10-19. [PMID: 30502823 DOI: 10.1016/j.zool.2018.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 11/21/2022]
Abstract
The present study describes keratinization and mucogenesis in the epidermis of an angler catfish Chaca chaca, using a series of immunochemical, fluorescence and histochemical methods. The epidermis is primarily mucogenic and shows characteristic specialised structures at irregular intervals. These structures are identified keratinized in nature. The superficial layer epithelial cells in the keratinized structures often detach from the underlying epithelial cells and exfoliate either singly or in the form of sheet. This is associated to provide protection by removing silty depositions, pathogens, and debris along with exfoliated keratinized cells/sheets periodically to keep the skin surface clean. Mucogenic epidermis is equipped with the mucous goblet cells and the club cells. Nevertheless, these cells are not discernible in the keratinized structures. This suggests an inverse relationship between mucogenesis and keratinization in the epidermis of the fish. The mucogenic epidermis is involved in the secretion of different classes of glycoproteins. These include glycoproteins with oxidizable vicinal diols, glycoproteins with O-sulphate esters and glycoproteins with sialic acid residues without O-acyl substitution. Secretion of these glycoproteins on the surface are associated to control the acidity of the acidic glycoproteins, to protect the skin surface against bacterial, viral infection and other pathogens, and help in lubrication to protect against abrasion during burrowing. Epidermal keratinization and glycoprotein characterization are associated with the physiological adaptations in relation to the characteristic habit and habitat of the fish.
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Böni LJ, Sanchez-Ferrer A, Widmer M, Biviano MD, Mezzenga R, Windhab EJ, Dagastine RR, Fischer P. Structure and Nanomechanics of Dry and Hydrated Intermediate Filament Films and Fibers Produced from Hagfish Slime Fibers. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40460-40473. [PMID: 30371056 DOI: 10.1021/acsami.8b17166] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Intermediate filaments (IFs) are known for their extensibility, flexibility, toughness, and their ability to hydrate. Using keratin-like IFs obtained from slime fibers from the invertebrate Atlantic hagfish ( Myxine glutinosa), films were produced by drop-casting and coagulation on the surface of a MgCl2 buffer. Drop-casting produced self-supporting, smooth, and dense films rich in β-sheets (61%), whereas coagulation formed thin, porous films with a nanorough surface and a lower β-sheet content (51%). The films hydrated and swelled immediately when immersed in water and did not dissolve. X-ray diffraction showed that the β-crystallites remained stable upon hydration, that swelling presumably happens in the amorphous C-terminal tail-domains of the IFs, and that high salt conditions caused a denser network mesh size, suggesting polyelectrolyte behavior. Hydration resulted in a roughly 1000-fold decrease in apparent Young's modulus from 109 to 106 Pa as revealed by atomic force microscopy nanoindentation. Nanoindentation-based power-law rheology and stress-relaxation measurements indicated viscoelasticity and a soft-solid hydrogel character for hydrated films, where roughly 80% of energy is elastically stored and 20% is dissipated. By pulling coagulation films from the buffer interface, macroscopic fibers with highly aligned IF β-crystals similar to natural hagfish fibers were produced. We propose that viscoelasticity and strong hydrogen bonding interactions with the buffer interface are crucial for the production of such long biomimetic fibers with aligned β-sheets. This study demonstrates that hagfish fiber IFs can be reconstituted into functional biomimetic materials that are stiff when dry and retain the ability to hydrate to become soft and viscoelastic when in water.
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Affiliation(s)
| | | | | | - M D Biviano
- Department of Chemical and Biomolecular Engineering , University of Melbourne , Melbourne 3010 , Australia
| | | | | | - R R Dagastine
- Department of Chemical and Biomolecular Engineering , University of Melbourne , Melbourne 3010 , Australia
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9
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Böni L, Fischer P, Böcker L, Kuster S, Rühs PA. Hagfish slime and mucin flow properties and their implications for defense. Sci Rep 2016; 6:30371. [PMID: 27460842 PMCID: PMC4961968 DOI: 10.1038/srep30371] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/30/2016] [Indexed: 01/09/2023] Open
Abstract
When hagfish (Myxinidae) are attacked by predators, they form a dilute, elastic, and cohesive defensive slime made of mucins and protein threads. In this study we propose a link between flow behavior and defense mechanism of hagfish slime. Oscillatory rheological measurements reveal that hagfish slime forms viscoelastic networks at low concentrations. Mucins alone did not contribute viscoelasticity, however in shear flow, viscosity was observed. The unidirectional flow, experienced by hagfish slime during suction feeding by predators, was mimicked with extensional rheology. Elongational stresses were found to increase mucin viscosity. The resulting higher resistance to flow could support clogging of the attacker's gills. Shear flow in contrast decreases the slime viscosity by mucin aggregation and leads to a collapse of the slime network. Hagfish may benefit from this collapse when trapped in their own slime and facing suffocation by tying a sliding knot with their body to shear off the slime. This removal could be facilitated by the apparent shear thinning behavior of the slime. Therefore hagfish slime, thickening in elongation and thinning in shear, presents a sophisticated natural high water content gel with flow properties that may be beneficial for both, defense and escape.
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Affiliation(s)
- Lukas Böni
- Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland
| | - Peter Fischer
- Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland
| | - Lukas Böcker
- Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland
| | - Simon Kuster
- Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland
| | - Patrick A. Rühs
- Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
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Nakai Y, Nakajima K, Robert J, Yaoita Y. Ouro proteins are not essential to tail regression during Xenopus tropicalis metamorphosis. Genes Cells 2016; 21:275-86. [PMID: 26847415 DOI: 10.1111/gtc.12337] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/14/2015] [Indexed: 11/28/2022]
Abstract
Tail regression is one of the most prominent transformations observed during anuran metamorphosis. A tadpole tail that is twice as long as the tadpole trunk nearly disappears within 3 days in Xenopus tropicalis. Several years ago, it was proposed that this phenomenon is driven by an immunological rejection of larval-skin-specific antigens, Ouro proteins. We generated ouro-knockout tadpoles using the TALEN method to reexamine this immunological rejection model. Both the ouro1- and ouro2-knockout tadpoles expressed a very low level of mRNA transcribed from a targeted ouro gene, an undetectable level of Ouro protein encoded by a target gene and a scarcely detectable level of the other Ouro protein from the untargeted ouro gene in tail skin. Furthermore, congenital athymic frogs were produced by Foxn1 gene modification. Flow cytometry analysis showed that mutant frogs lacked splenic CD8(+) T cells, which play a major role in cytotoxic reaction. Furthermore, T-cell-dependent skin allograft rejection was dramatically impaired in mutant frogs. None of the knockout tadpoles showed any significant delay in the process of tail shortening during the climax of metamorphosis, which shows that Ouro proteins are not essential to tail regression at least in Xenopus tropicalis and argues against the immunological rejection model.
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Affiliation(s)
- Yuya Nakai
- Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan
| | - Keisuke Nakajima
- Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan
| | - Jacques Robert
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, 14642, NY, USA
| | - Yoshio Yaoita
- Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan
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Böni L, Rühs PA, Windhab EJ, Fischer P, Kuster S. Gelation of Soy Milk with Hagfish Exudate Creates a Flocculated and Fibrous Emulsion- and Particle Gel. PLoS One 2016; 11:e0147022. [PMID: 26808048 PMCID: PMC4726539 DOI: 10.1371/journal.pone.0147022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/27/2015] [Indexed: 11/19/2022] Open
Abstract
Hagfish slime is an ultra dilute, elastic and cohesive hydrogel that deploys within milliseconds in cold seawater from a glandularly secreted exudate. The slime is made of long keratin-like fibers and mucin-like glycoproteins that span a network which entraps water and acts as a defense mechanism against predators. Unlike other hydrogels, the slime only confines water physically and is very susceptible to mechanical stress, which makes it unsuitable for many processing operations and potential applications. Despite its huge potential, little work has been done to improve and functionalize the properties of this hydrogel. To address this shortcoming, hagfish exudate was mixed with a soy protein isolate suspension (4% w/v) and with a soy emulsion (commercial soy milk) to form a more stable structure and combine the functionalities of a suspension and emulsion with those of the hydrogel. Hagfish exudate interacted strongly with the soy systems, showing a markedly increased viscoelasticity and water retention. Hagfish mucin was found to induce a depletion and bridging mechanism, which caused the emulsion and suspension to flocculate, making "soy slime", a cohesive and cold-set emulsion- and particle gel. The flocculation network increases viscoelasticity and substantially contributes to liquid retention by entrapping liquid in the additional confinements between aggregated particles and protein fibers. Because the mucin-induced flocculation resembles the salt- or acid-induced flocculation in tofu curd production, the soy slime was cooked for comparison. The cooked soy slime was similar to conventional cooked tofu, but possessed a long-range cohesiveness from the fibers. The fibrous, cold-set, and curd-like structure of the soy slime represents a novel way for a cold coagulation and fiber incorporation into a suspension or emulsion. This mechanism could be used to efficiently gel functionalized emulsions or produce novel tofu-like structured food products.
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Affiliation(s)
- Lukas Böni
- Food Process Engineering Group, Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland
| | - Patrick A. Rühs
- Complex Materials Group, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Erich J. Windhab
- Food Process Engineering Group, Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland
| | - Peter Fischer
- Food Process Engineering Group, Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland
| | - Simon Kuster
- Food Process Engineering Group, Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland
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12
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Alibardi L. The Process of Cornification Evolved From the Initial Keratinization in the Epidermis and Epidermal Derivatives of Vertebrates: A New Synthesis and the Case of Sauropsids. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 327:263-319. [DOI: 10.1016/bs.ircmb.2016.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fu J, Guerette PA, Miserez A. Self-Assembly of Recombinant Hagfish Thread Keratins Amenable to a Strain-Induced α-Helix to β-Sheet Transition. Biomacromolecules 2015; 16:2327-39. [PMID: 26102237 DOI: 10.1021/acs.biomac.5b00552] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hagfish slime threads are assembled from protein-based bundles of intermediate filaments (IFs) that undergo a strain-induced α-helical coiled-coil to β-sheet transition. Draw processing of native fibers enables the creation of mechanically tuned materials, and under optimized conditions this process results in mechanical properties similar to spider dragline silk. In this study, we develop the foundation for the engineering of biomimetic recombinant hagfish thread keratin (TK)-based materials. The two protein constituents from the hagfish Eptatretus stoutii thread, named EsTKα and EsTKγ, were expressed in Escherichia coli and purified. Individual (rec)EsTKs and mixtures thereof were subjected to stepwise dialysis to evaluate their protein solubility, folding, and self-assembly propensities. Conditions were identified that resulted in the self-assembly of coiled-coil rich IF-like filaments, as determined by circular dichroism (CD) and transmission electron microscopy (TEM). Rheology experiments indicated that the concentrated filaments assembled into gel-like networks exhibiting a rheological response reminiscent to that of IFs. Notably, the self-assembled filaments underwent an α-helical coiled-coil to β-sheet transition when subjected to oscillatory shear, thus mimicking the critical characteristic responsible for mechanical strengthening of native hagfish threads. We propose that our data establish the foundation to create robust and tunable recombinant TK-based materials whose mechanical properties are controlled by a strain-induced α-helical coiled-coil to β-sheet transition.
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Affiliation(s)
- Jing Fu
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798
| | - Paul A Guerette
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.,‡Energy Research Institute at Nanyang Technological University (ERI@N), 50 Nanyang Drive, Singapore, 637553
| | - Ali Miserez
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.,§School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive Singapore 637551
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14
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Abstract
Hagfishes thwart attacks by fish predators by producing liters of defensive slime. The slime is produced when slime gland exudate is released into the predator's mouth, where it deploys in a fraction of a second and clogs the gills. Slime exudate is composed mainly of secretory products from two cell types, gland mucous cells and gland thread cells, which produce the mucous and fibrous components of the slime, respectively. Here, we review what is known about the composition of the slime, morphology of the slime gland, and physiology of the cells that produce the slime. We also discuss several of the mechanisms involved in the deployment of both mucous and thread cells during the transition from thick glandular exudate to ultradilute material. We review biomechanical aspects of the slime, along with recent efforts to produce biomimetic slime thread analogs, and end with a discussion of how hagfish slime may have evolved.
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Affiliation(s)
- Douglas S. Fudge
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Sarah Schorno
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Shannon Ferraro
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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15
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Simões MG, Bensimon-Brito A, Fonseca M, Farinho A, Valério F, Sousa S, Afonso N, Kumar A, Jacinto A. Denervation impairs regeneration of amputated zebrafish fins. BMC DEVELOPMENTAL BIOLOGY 2014; 14:49. [PMID: 25551555 PMCID: PMC4333893 DOI: 10.1186/s12861-014-0049-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 12/18/2014] [Indexed: 11/24/2022]
Abstract
BACKGROUND Zebrafish are able to regenerate many of its tissues and organs after damage. In amphibians this process is regulated by nerve fibres present at the site of injury, which have been proposed to release factors into the amputated limbs/fins, promoting and sustaining the proliferation of blastemal cells. Although some candidate factors have been proposed to mediate the nerve dependency of regeneration, the molecular mechanisms involved in this process remain unclear. RESULTS We have used zebrafish as a model system to address the role of nerve fibres in fin regeneration. We have developed a protocol for pectoral fin denervation followed by amputation and analysed the regenerative process under this experimental conditions. Upon denervation fins were able to close the wound and form a wound epidermis, but could not establish a functional apical epithelial cap, with a posterior failure of blastema formation and outgrowth, and the accumulation of several defects. The expression patterns of genes known to be key players during fin regeneration were altered upon denervation, suggesting that nerves can contribute to the regulation of the Fgf, Wnt and Shh pathways during zebrafish fin regeneration. CONCLUSIONS Our results demonstrate that proper innervation of the zebrafish pectoral fin is essential for a successful regenerative process, and establish this organism as a useful model to understand the molecular and cellular mechanisms of nerve dependence, during vertebrate regeneration.
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Affiliation(s)
- Mariana G Simões
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal.
- CEDOC, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.
| | - Anabela Bensimon-Brito
- CEDOC, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.
- Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal.
| | - Mariana Fonseca
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal.
| | - Ana Farinho
- CEDOC, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.
| | - Fábio Valério
- CEDOC, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.
| | - Sara Sousa
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal.
| | - Nuno Afonso
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal.
| | - Anoop Kumar
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK.
| | - Antonio Jacinto
- CEDOC, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.
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16
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Wang M, Wang Y, Zhang L, Wang J, Hong H, Wang D. Quantitative proteomic analysis reveals the mode-of-action for chronic mercury hepatotoxicity to marine medaka (Oryzias melastigma). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 130-131:123-131. [PMID: 23416409 DOI: 10.1016/j.aquatox.2013.01.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/16/2013] [Accepted: 01/18/2013] [Indexed: 06/01/2023]
Abstract
Mercury (Hg) is a widespread persistent pollutant in aquatic ecosystems. We investigated the protein profiles of medaka (Oryzias melastigma) liver chronically exposed to different mercuric chloride (HgCl2) concentrations (1 or 10 μg/L) for 60 d using two-dimensional difference gel electrophoresis (2D-DIGE), as well as cell ultrastructure and Hg content analysis of the hepatic tissue. The results showed that Hg exposure significantly increased metal accumulation in the liver, and subsequently damaged liver ultrastructure. Comparison of the 2D-DIGE protein profiles of the exposed and control groups revealed that the abundance of 45 protein spots was remarkably altered in response to Hg treatment. The altered spots were subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis, with the resultant identification of 33 spots. These proteins were mainly involved in cytoskeleton assembly, oxidative stress, and energy production. Among them, several proteins related to mitochondrial function (e.g. respiratory metabolism) were significantly altered in the treated hepatocytes, implying that this organelle might be the primary target for Hg attack in the cells. This study provided new insights into the molecular mechanisms and/or toxic pathways by which chronic Hg hepatotoxicity affects aquatic organisms, and also provided basic information for screening potential biomarkers for aquatic Hg monitoring.
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Affiliation(s)
- Minghua Wang
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen 361005, China
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17
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Vandebergh W, Bossuyt F. Radiation and Functional Diversification of Alpha Keratins during Early Vertebrate Evolution. Mol Biol Evol 2011; 29:995-1004. [DOI: 10.1093/molbev/msr269] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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18
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Tian L, Wang M, Li X, Lam PKS, Wang M, Wang D, Chou HN, Li Y, Chan LL. Proteomic modification in gills and brains of medaka fish (Oryzias melastigma) after exposure to a sodium channel activator neurotoxin, brevetoxin-1. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 104:211-217. [PMID: 21632025 DOI: 10.1016/j.aquatox.2011.04.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 04/21/2011] [Accepted: 04/30/2011] [Indexed: 05/30/2023]
Abstract
Although brevetoxins (PbTxs) produced by the marine dinoflagellate Karenia brevis are known to be absorbed across gill membranes and exert their acute toxic effects through an ion-channel mediated pathway in neural tissue, the exact biochemical mechanism concerning PbTxs neurotoxicity in neural tissue and gas-exchange organs has not been well elucidated. In this study, we calculated the LC(50) value of PbTx-1 using the medaka fish model, and presented the molecular responses of sub-acute exposure to PbTx-1 with proteomic method. By adopting two-dimensional electrophoresis, the abundances of 14 and 24 proteins were found to be remarkably altered in the gills and brains, respectively, in response to toxin exposure. Thirteen gill and twenty brain proteins were identified using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis. These proteins could be categorized into diverse functional classes such as cell structure, macromolecule metabolism, signal transduction and neurotransmitter release. These findings can help to elucidate the possible pathways by which aquatic toxins affect marine organisms within target organs.
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Affiliation(s)
- Li Tian
- State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
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19
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Kurokawa I, Takahashi K, Moll I, Moll R. Expression of keratins in cutaneous epithelial tumors and related disorders - distribution and clinical significance. Exp Dermatol 2011; 20:217-28. [DOI: 10.1111/j.1600-0625.2009.01006.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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20
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Karlsen OA, Bjørneklett S, Berg K, Brattås M, Bohne-Kjersem A, Grøsvik BE, Goksøyr A. Integrative environmental genomics of Cod (Gadus morhua): the proteomics approach. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:494-507. [PMID: 21391094 DOI: 10.1080/15287394.2011.550559] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Atlantic cod (Gadus morhua) is an essential species in North Atlantic fisheries and increasingly relevant as an aquaculture species. However, potential conflicts with both coastal industry and petroleum industry expanding into northern waters make it important to understand how effluents (produced water, pharmaceuticals, food contaminants, and feed contaminants) affect the growth, reproduction, and health of this species in order to maintain a sustainable cod population and a healthy human food source, and to discover biomarkers for environmental monitoring and risk assessment. The ongoing genome sequencing effort of Atlantic cod has opened the possibility for a systems biology approach to elucidate molecular mechanisms of toxicity. Our study aims to be a first step toward such a systems toxicology understanding of genomic responses to environmental insults. A toxicogenomic approach was initiated that is combining data generated from proteomics analyses and transcriptomics analyses, and the concurrent development of searchable expressed sequence tags (EST) databases and genomic databases. This interdisciplinary study may also open new possibilities of gene annotation and pathway analyses.
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21
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Lin YC, Broedersz CP, Rowat AC, Wedig T, Herrmann H, Mackintosh FC, Weitz DA. Divalent cations crosslink vimentin intermediate filament tail domains to regulate network mechanics. J Mol Biol 2010; 399:637-44. [PMID: 20447406 DOI: 10.1016/j.jmb.2010.04.054] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 04/24/2010] [Accepted: 04/27/2010] [Indexed: 01/30/2023]
Abstract
Intermediate filament networks in the cytoplasm and nucleus are critical for the mechanical integrity of metazoan cells. However, the mechanism of crosslinking in these networks and the origins of their mechanical properties are not understood. Here, we study the elastic behavior of in vitro networks of the intermediate filament protein vimentin. Rheological experiments reveal that vimentin networks stiffen with increasing concentrations of Ca(2+) and Mg(2+), showing that divalent cations act as crosslinkers. We quantitatively describe the elastic response of vimentin networks over five decades of applied stress using a theory that treats the divalent cations as crosslinkers: at low stress, the behavior is entropic in origin, and increasing stress pulls out thermal fluctuations from single filaments, giving rise to a nonlinear response; at high stress, enthalpic stretching of individual filaments significantly modifies the nonlinearity. We investigate the elastic properties of networks formed by a series of protein variants with stepwise tail truncations and find that the last 11 amino acids of the C-terminal tail domain mediate crosslinking by divalent ions. We determined the single-filament persistence length, l(P) approximately 0.5 mum, and Young's modulus, Y approximately 9 MPa; both are consistent with literature values. Our results provide insight into a crosslinking mechanism for vimentin networks and suggest that divalent ions may help regulate the cytoskeletal structure and mechanical properties of cells.
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Affiliation(s)
- Yi-Chia Lin
- Department of Physics, Harvard University, Pierce 231, 29 Oxford Street, Cambridge, MA 02138, USA
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22
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Bragulla HH, Homberger DG. Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia. J Anat 2010; 214:516-59. [PMID: 19422428 DOI: 10.1111/j.1469-7580.2009.01066.x] [Citation(s) in RCA: 409] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Historically, the term 'keratin' stood for all of the proteins extracted from skin modifications, such as horns, claws and hooves. Subsequently, it was realized that this keratin is actually a mixture of keratins, keratin filament-associated proteins and other proteins, such as enzymes. Keratins were then defined as certain filament-forming proteins with specific physicochemical properties and extracted from the cornified layer of the epidermis, whereas those filament-forming proteins that were extracted from the living layers of the epidermis were grouped as 'prekeratins' or 'cytokeratins'. Currently, the term 'keratin' covers all intermediate filament-forming proteins with specific physicochemical properties and produced in any vertebrate epithelia. Similarly, the nomenclature of epithelia as cornified, keratinized or non-keratinized is based historically on the notion that only the epidermis of skin modifications such as horns, claws and hooves is cornified, that the non-modified epidermis is a keratinized stratified epithelium, and that all other stratified and non-stratified epithelia are non-keratinized epithelia. At this point in time, the concepts of keratins and of keratinized or cornified epithelia need clarification and revision concerning the structure and function of keratin and keratin filaments in various epithelia of different species, as well as of keratin genes and their modifications, in view of recent research, such as the sequencing of keratin proteins and their genes, cell culture, transfection of epithelial cells, immunohistochemistry and immunoblotting. Recently, new functions of keratins and keratin filaments in cell signaling and intracellular vesicle transport have been discovered. It is currently understood that all stratified epithelia are keratinized and that some of these keratinized stratified epithelia cornify by forming a Stratum corneum. The processes of keratinization and cornification in skin modifications are different especially with respect to the keratins that are produced. Future research in keratins will provide a better understanding of the processes of keratinization and cornification of stratified epithelia, including those of skin modifications, of the adaptability of epithelia in general, of skin diseases, and of the changes in structure and function of epithelia in the course of evolution. This review focuses on keratins and keratin filaments in mammalian tissue but keratins in the tissues of some other vertebrates are also considered.
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Affiliation(s)
- Hermann H Bragulla
- Department of Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, 70803, USA.
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23
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Bohne-Kjersem A, Bache N, Meier S, Nyhammer G, Roepstorff P, Saele O, Goksøyr A, Grøsvik BE. Biomarker candidate discovery in Atlantic cod (Gadus morhua) continuously exposed to North Sea produced water from egg to fry. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2010; 96:280-289. [PMID: 20031237 DOI: 10.1016/j.aquatox.2009.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 11/03/2009] [Accepted: 11/08/2009] [Indexed: 05/28/2023]
Abstract
In this study Atlantic cod (Gadus morhua) were exposed to different levels of North Sea produced water (PW) and 17beta-oestradiol (E(2)), a natural oestrogen, from egg to fry stage (90 days). By comparing changes in protein expression following E(2) exposure to changes induced by PW treatment, we were able to compare the induced changes by PW to the mode of action of oestrogens. Changes in the proteome in response to exposure in whole cod fry (approximately 80 days post-hatching, dph) were detected by two-dimensional gel electrophoresis and image analysis and identified by MALDI-ToF-ToF mass spectrometry, using a newly developed cod EST database and the NCBI database. Many of the protein changes occurred at low levels (0.01% and 0.1% PW) of exposure, indicating putative biological responses at lower levels than previously detected. Using discriminant analysis, we identified a set of protein changes that may be useful as biomarker candidates of produced water (PW) and oestradiol exposure in Atlantic cod fry. The biomarker candidates discovered in this study may, following validation, prove effective as diagnostic tools in monitoring exposure and effects of discharges from the petroleum industry offshore, aiding future environmental risk analysis and risk management.
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Affiliation(s)
- Anneli Bohne-Kjersem
- Department of Molecular Biology, University of Bergen, PB 7800, N-5020 Bergen, Norway.
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24
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The keratin-related Ouroboros proteins function as immune antigens mediating tail regression in Xenopus metamorphosis. Proc Natl Acad Sci U S A 2009; 106:18309-14. [PMID: 19826093 DOI: 10.1073/pnas.0708837106] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tail resorption during amphibian metamorphosis has been thought to be controlled mainly by a cell-autonomous mechanism of programmed cell death triggered by thyroid hormone. However, we have proposed a role for the immune response in metamorphosis, based on the finding that syngeneic grafts of tadpole tail skin into adult Xenopus animals are rejected by T cells. To test this, we identified two tail antigen genes called ouro1 and ouro2 that encode keratin-related proteins. Recombinant Ouro1 and Ouro2 proteins generated proliferative responses in vitro in T cells isolated from naive adult Xenopus animals. These genes were expressed specifically in the tail skin at the climax of metamorphosis. Overexpression of ouro1 and ouro2 induced T-cell accumulation and precocious tail degeneration after full differentiation of adult-type T cells when overexpressed in the tail region. When the expression of ouro1 and ouro2 were knocked down, tail skin tissue remained even after metamorphosis was complete. Our findings indicate that Ouro proteins participate in the process of tail regression as immune antigens and highlight the possibility that the acquired immune system contributes not only to self-defense but also to remodeling processes in vertebrate morphogenesis.
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25
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Di Bella MA, Carbone MC, D'Amato M, Alessandro R, De Leo G. The identification and localization of two intermediate filament proteins in the tunic of Styela plicata (Tunicata, Styelidae). Tissue Cell 2009; 41:381-9. [PMID: 19524277 DOI: 10.1016/j.tice.2009.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 04/10/2009] [Indexed: 11/26/2022]
Abstract
The intermediate filament (IF) proteins Styela C and Styela D from the tunicate Styela (Urochordata) are co-expressed in all epidermal cells and they are thought to behave as type I and type II keratins. These two IF proteins, Styela C and Styela D, were identified in immunoblots of proteins isolated from the tunic of Styela plicata. The occurrence and distribution of these proteins within the tunic of this ascidian was examined by means of immunofluorescence and immunoperoxidase techniques, using anti-Styela C and anti-Styela D antibodies. In addition, immuno-electron microscopy of the tunic showed that the two proteins are located in the cuticle layer and in the tunic matrix. These results represent the first data about the presence of IF proteins in the tunic of adult ascidian S. plicata. The possible involvement of these IF proteins in reinforcing the integrity of the tunic, that represents the interface between the animal body and the external environment, is discussed.
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Affiliation(s)
- Maria Antonietta Di Bella
- Dipartimento di Biopatologia e Metodologie Biomediche, Sezione di Biologia e Genetica, Università degli Studi di Palermo, Italy.
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26
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Schaffeld M, Haberkamp M, Schätzlein S, Neumann S, Hunzinger C. A novel and ancient group of type I keratins with members in bichir, sturgeon and gar. Front Zool 2007; 4:16. [PMID: 17553169 PMCID: PMC1896152 DOI: 10.1186/1742-9994-4-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Accepted: 06/06/2007] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Vertebrate epithelial cells typically express a specific set of keratins. In teleosts, keratins are also present in a variety of mesenchymal cells, which usually express vimentin. Significantly, our previous studies revealed that virtually all known teleost keratins evolved independently from those present in terrestrial vertebrates. To further elucidate the evolutionary scenario that led to the large variety of keratins and their complex expression patterns in present day teleosts, we have investigated their presence in bichir, sturgeon and gar. RESULTS We have discovered a novel group of type I keratins with members in all three of these ancient ray-finned fish, but apparently no counterparts are present in any other vertebrate class so far investigated, including the modern teleost fish. From sturgeon and gar we sequenced one and from bichir two members of this novel keratin group. By complementary keratin blot-binding assays and peptide mass fingerprinting using MALDI-TOF mass spectrometry, in sturgeon we were able to assign the sequence to a prominent protein spot, present exclusively in a two-dimensionally separated cytoskeletal preparation of skin, thus identifying it as an epidermally expressed type I keratin. In contrast to the other keratins we have so far sequenced from bichir, sturgeon and gar, these new sequences occupy a rather basal position within the phylogenetic tree of type I keratins, in a close vicinity to the keratins we previously cloned from river lamprey. CONCLUSION Thus, this new K14 group seem to belong to a very ancient keratin branch, whose functional role has still to be further elucidated. Furthermore, the exclusive presence of this keratin group in bichir, sturgeon and gar points to the close phylogenetic relationship of these ray- finned fish, an issue still under debate among taxonomists.
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Affiliation(s)
- Michael Schaffeld
- Institute of Zoology, Johannes-von-Müller-Weg 6, Johannes Gutenberg University, D-55099 Mainz, Germany
| | - Mark Haberkamp
- Institute of Zoology, Johannes-von-Müller-Weg 6, Johannes Gutenberg University, D-55099 Mainz, Germany
| | - Sonja Schätzlein
- Dept. of Gastroenterology, Medical School Hannover, Carl Neuberg Str. 1, K11, E01, R1400, 30629 Hannover, Germany
| | - Sebastian Neumann
- Institute of Zoology, Johannes-von-Müller-Weg 6, Johannes Gutenberg University, D-55099 Mainz, Germany
| | - Christian Hunzinger
- Merck KGaA, Central Services Analytics, Central Product Analytics/Bioanalytics, Frankfurter Str. 250, D-64293 Darmstadt, Germany
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Perng MD, Zhang Q, Quinlan RA. Insights into the beaded filament of the eye lens. Exp Cell Res 2007; 313:2180-8. [PMID: 17490642 PMCID: PMC5073188 DOI: 10.1016/j.yexcr.2007.04.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 03/30/2007] [Accepted: 04/03/2007] [Indexed: 12/28/2022]
Abstract
Filensin (BFSP1) and CP49 (BFSP2) represent two members of the IF protein superfamily that are thus far exclusively expressed in the eye lens. Mutations in both proteins cause lens cataract and careful consideration of the detail of these cataract phenotypes alerts us to several interesting features concerning the function of filensin (BFSP1) and CP49 (BFSP2) in the lens. With the first filensin (BFSP1) mutation now having been reported to cause a recessive cataract phenotype, there is the suggestion that the mutation could predispose heterozygote carriers to the early onset of age-related nuclear cataract. In the case of CP49 (BFSP2), there are now three unrelated families who have been identified with a common E233 Delta mutation. Very interestingly this is linked to myopia in one family. Despite the apparent phenotypic differences of the filensin (BFSP1) and CP49 (BFSP2) mutations, the data are still consistent with the beaded filament proteins being essential for lens function and specifically contributing to the optical properties of the lens. The fact that none of the mutations thus far reported affect either the conserved LNDR or TYRKLLEGE motifs that flank the central rod domain supports the view that this pair of IF proteins have unusual structural features and a distinctive assembly mechanism. The multiple sequence divergences suggest these proteins have been adapted to the specific functional requirements of lens fibre cells, a function that can be traced from squid to man.
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Affiliation(s)
- Ming-Der Perng
- School of Biological and Biomedical Sciences, The University of Durham, DH1 3LE, UK.
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