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Velamoor S, Mitchell A, Bostina M, Harland D. Processing hair follicles for transmission electron microscopy. Exp Dermatol 2021; 31:110-121. [PMID: 34351648 DOI: 10.1111/exd.14439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 11/30/2022]
Abstract
Transmission electron microscopy (TEM) has greatly advanced our knowledge of hair growth and follicle morphogenesis, but complex preparations such as fixation, dehydration and embedding compromise ultrastructure. While recent developments with cryofixation have been shown to preserve the ultrastructure of biological materials close to native state, they do have limitations. This review will focus on each stage of the TEM sample preparation process and their effects on the structural integrity of follicles.
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Affiliation(s)
- Sailakshmi Velamoor
- Proteins and Metabolites, AgResearch Limited, Lincoln, New Zealand.,Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Allan Mitchell
- Otago Micro and Nano Imaging, University of Otago, Dunedin, New Zealand
| | - Mihnea Bostina
- Microbiology and Immunology, University of Otago, Dunedin, New Zealand.,Otago Micro and Nano Imaging, University of Otago, Dunedin, New Zealand
| | - Duane Harland
- Proteins and Metabolites, AgResearch Limited, Lincoln, New Zealand
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Alibardi L. Vertebrate keratinization evolved into cornification mainly due to transglutaminase and sulfhydryl oxidase activities on epidermal proteins: An immunohistochemical survey. Anat Rec (Hoboken) 2021; 305:333-358. [PMID: 34219408 DOI: 10.1002/ar.24705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/27/2021] [Accepted: 05/04/2021] [Indexed: 02/06/2023]
Abstract
The epidermis of vertebrates forms an extended organ to protect and exchange gas, water, and organic molecules with aquatic and terrestrial environments. Herein, the processes of keratinization and cornification in aquatic and terrestrial vertebrates were compared using immunohistochemistry. Keratins with low cysteine and glycine contents form the main bulk of proteins in the anamniote epidermis, which undergoes keratinization. In contrast, specialized keratins rich in cysteine-glycine and keratin associated corneous proteins rich in cysteine, glycine, and tyrosine form the bulk of proteins of amniote soft cornification in the epidermis and hard cornification in scales, claws, beak, feathers, hairs, and horns. Transglutaminase (TGase) and sulfhydryl oxidase (SOXase) are the main enzymes involved in cornification. Their evolution was fundamental for the terrestrial adaptation of vertebrates. Immunohistochemistry results revealed that TGase and SOXase were low to absent in fish and amphibian epidermis, while they increased in the epidermis of amniotes with the evolution of the stratum corneum and skin appendages. TGase aids the formation of isopeptide bonds, while SOXase forms disulfide bonds that generate numerous cross-links between keratins and associated corneous proteins, likely increasing the mechanical resistance and durability of the amniote epidermis and its appendages. TGase is low to absent in the beta-corneous layers of sauropsids but is detected in the softer but pliable alpha-layers of sauropsids, mammalian epidermis, medulla, and inner root sheath of hairs. SOXase is present in hard and soft corneous appendages of reptiles, birds, and mammals, and determines cross-linking among corneous proteins of scales, claws, beaks, hairs, and feathers.
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Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab Padova and University of Bologna, Bologna, Italy
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Hintze M, Griesing S, Michels M, Blanck B, Wischhof L, Hartmann D, Bano D, Franz T. Alopecia in Harlequin mutant mice is associated with reduced AIF protein levels and expression of retroviral elements. Mamm Genome 2021; 32:12-29. [PMID: 33367954 PMCID: PMC7878237 DOI: 10.1007/s00335-020-09854-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 11/23/2020] [Indexed: 11/25/2022]
Abstract
We investigated the contribution of apoptosis-inducing factor (AIF), a key regulator of mitochondrial biogenesis, in supporting hair growth. We report that pelage abnormalities developed during hair follicle (HF) morphogenesis in Harlequin (Hq) mutant mice. Fragility of the hair cortex was associated with decreased expression of genes encoding structural hair proteins, though key transcriptional regulators of HF development were expressed at normal levels. Notably, Aifm1 (R200 del) knockin males and Aifm1(R200 del)/Hq females showed minor hair defects, despite substantially reduced AIF levels. Furthermore, we cloned the integrated ecotropic provirus of the Aifm1Hq allele. We found that its overexpression in wild-type keratinocyte cell lines led to down-regulation of HF-specific Krt84 and Krtap3-3 genes without altering Aifm1 or epidermal Krt5 expression. Together, our findings imply that pelage paucity in Hq mutant mice is mechanistically linked to severe AIF deficiency and is associated with the expression of retroviral elements that might potentially influence the transcriptional regulation of structural hair proteins.
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Affiliation(s)
- Maik Hintze
- Institute of Anatomy, Neuroanatomy, Medical Faculty, UKB, University of Bonn, Bonn, Germany.
- Medical Department, MSH Medical School Hamburg, Hamburg, Germany.
| | - Sebastian Griesing
- Institute of Anatomy, Neuroanatomy, Medical Faculty, UKB, University of Bonn, Bonn, Germany
- Dept. of Oncology, National Taiwan University Hospital, Taipei City, 100, Taiwan, ROC
| | - Marion Michels
- Institute of Anatomy, Neuroanatomy, Medical Faculty, UKB, University of Bonn, Bonn, Germany
| | - Birgit Blanck
- Institute of Anatomy, Neuroanatomy, Medical Faculty, UKB, University of Bonn, Bonn, Germany
| | - Lena Wischhof
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Dieter Hartmann
- Institute of Anatomy, Neuroanatomy, Medical Faculty, UKB, University of Bonn, Bonn, Germany
| | - Daniele Bano
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Thomas Franz
- Institute of Anatomy, Neuroanatomy, Medical Faculty, UKB, University of Bonn, Bonn, Germany
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Abstract
Mammalian hair fibres can be structurally divided into three main components: a cuticle, cortex and sometimes a medulla. The cuticle consists of a thin layer of overlapping cells on the surface of the fibre, constituting around 10% of the total fibre weight. The cortex makes up the remaining 86-90% and is made up of axially aligned spindle-shaped cells of which three major types have been recognised in wool: ortho, meso and para. Cortical cells are packed full of macrofibril bundles, which are a composite of aligned intermediate filaments embedded in an amorphous matrix. The spacing and three-dimensional arrangement of the intermediate filaments vary with cell type. The medulla consists of a continuous or discontinuous column of horizontal spaces in the centre of the cortex that becomes more prevalent as the fibre diameter increases.
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Abstract
The growth of hairs occurs during the anagen phase of the follicle cycle. Hair growth begins with basement membrane-bound stem cells (mother cells) around the dermal papilla neck which continuously bud off daughter cells which further divide as a transient amplifying population. Division ceases as cell line differentiation begins, which entails changes in cell junctions, cell shape and position, and cell-line specific cytoplasmic expression of keratin and trichohyalin. As the differentiating cells migrate up the bulb, nuclear function ceases in cortex, cuticle and inner root sheath (IRS) layers. Past the top of the bulb, cell shape/position changes cease, and there is a period of keratin and keratin-associated protein (KAP) synthesis in fibre cell lines, with increases, in particular of KAP species. A gradual keratinization process begins in the cortex at this point and then non-keratin cell components are increasingly broken down. Terminal cornification, or hardening, is associated with water loss and precipitation of keratin. In the upper follicle, the hair, now in its mature form, detaches from the IRS, which is then extracted of material and becomes fragmented to release the fibre. Finally, the sebaceous and sudoriferous (if present) glands coat the fibre in lipid-rich material and the fibre emerges from the skin. This chapter follows the origin of the hair growth in the lower bulb and traces the development of the various cell lines.
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Alibardi L. Ultrastructural localization of hair keratins, high sulfur keratin-associated proteins and sulfhydryl oxidase in the human hair. Anat Sci Int 2016; 92:248-261. [DOI: 10.1007/s12565-016-0330-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/29/2016] [Indexed: 11/28/2022]
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Boykins LG, Jones JCR, Estraño CE, Schwartzbach SD, Skalli O. Pre-embedding Double-Label Immunoelectron Microscopy of Chemically Fixed Tissue Culture Cells. Methods Mol Biol 2016; 1474:217-32. [PMID: 27515083 PMCID: PMC5734918 DOI: 10.1007/978-1-4939-6352-2_13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Localization of specific proteins within cells at the nanometer level of resolution is central to understanding how these proteins function in cell processes such as motility and intracellular trafficking. Such localization can be achieved by combining transmission electron microscopy (TEM) with immunogold labeling. Here we describe a pre-embedding, indirect gold immunolabeling approach to localize two different proteins of interest with secondary antibodies labeled with gold particles of different sizes in cells grown on cover slips. In this protocol, the cells are immunolabeled prior to being embedded in an epoxy resin for ultrathin sectioning. The protocol also includes strategies for optimizing the balance between ultrastructure and antigen preservation, steps to minimize nonspecific antibody binding, and steps to optimize antibody penetration.
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Affiliation(s)
- Lou G Boykins
- Department of Biological Sciences, The University of Memphis, 103 Life Sciences Bldg, Memphis, TN, 38152, USA
| | - Jonathan C R Jones
- School of Molecular Biosciences, Washington State University, BLS 202F, 1770 NE Stadium Way, Pullman, WA, 99164, USA
| | - Carlos E Estraño
- Department of Biological Sciences, The University of Memphis, 103 Life Sciences Bldg, Memphis, TN, 38152, USA
| | - Steven D Schwartzbach
- Department of Biological Sciences, The University of Memphis, 103 Life Sciences Bldg, Memphis, TN, 38152, USA
| | - Omar Skalli
- Department of Biological Sciences, The University of Memphis, 103 Life Sciences Bldg, Memphis, TN, 38152, USA.
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Characterization of the human hair shaft cuticle-specific keratin-associated protein 10 family. J Invest Dermatol 2013; 133:2780-2782. [PMID: 23702583 DOI: 10.1038/jid.2013.233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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