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Ho M, Thompson B, Fisk JN, Nebert DW, Bruford EA, Vasiliou V, Bunick CG. Update of the keratin gene family: evolution, tissue-specific expression patterns, and relevance to clinical disorders. Hum Genomics 2022; 16:1. [PMID: 34991727 PMCID: PMC8733776 DOI: 10.1186/s40246-021-00374-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/17/2021] [Indexed: 12/15/2022] Open
Abstract
Intermediate filament (IntFil) genes arose during early metazoan evolution, to provide mechanical support for plasma membranes contacting/interacting with other cells and the extracellular matrix. Keratin genes comprise the largest subset of IntFil genes. Whereas the first keratin gene appeared in sponge, and three genes in arthropods, more rapid increases in keratin genes occurred in lungfish and amphibian genomes, concomitant with land animal-sea animal divergence (~ 440 to 410 million years ago). Human, mouse and zebrafish genomes contain 18, 17 and 24 non-keratin IntFil genes, respectively. Human has 27 of 28 type I "acidic" keratin genes clustered at chromosome (Chr) 17q21.2, and all 26 type II "basic" keratin genes clustered at Chr 12q13.13. Mouse has 27 of 28 type I keratin genes clustered on Chr 11, and all 26 type II clustered on Chr 15. Zebrafish has 18 type I keratin genes scattered on five chromosomes, and 3 type II keratin genes on two chromosomes. Types I and II keratin clusters-reflecting evolutionary blooms of keratin genes along one chromosomal segment-are found in all land animal genomes examined, but not fishes; such rapid gene expansions likely reflect sudden requirements for many novel paralogous proteins having divergent functions to enhance species survival following sea-to-land transition. Using data from the Genotype-Tissue Expression (GTEx) project, tissue-specific keratin expression throughout the human body was reconstructed. Clustering of gene expression patterns revealed similarities in tissue-specific expression patterns for previously described "keratin pairs" (i.e., KRT1/KRT10, KRT8/KRT18, KRT5/KRT14, KRT6/KRT16 and KRT6/KRT17 proteins). The ClinVar database currently lists 26 human disease-causing variants within the various domains of keratin proteins.
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Affiliation(s)
- Minh Ho
- Department of Dermatology, Yale University, 333 Cedar St., LCI 501, PO Box 208059, New Haven, CT, 06520-8059, USA
| | - Brian Thompson
- Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, 06511, USA
| | - Jeffrey Nicholas Fisk
- Program of Computational Biology and Bioinformatics, Yale University, New Haven, CT, 06511, USA
| | - Daniel W Nebert
- Departments of Pediatrics and Molecular and Developmental Biology, Cincinnati Children's Research Center, Cincinnati, OH, 45229, USA
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA
| | - Elspeth A Bruford
- HUGO Gene Nomenclature Committee (HGNC), EMBL-EBI, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SD, UK
- Department of Haematology, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, 06511, USA
| | - Christopher G Bunick
- Department of Dermatology, Yale University, 333 Cedar St., LCI 501, PO Box 208059, New Haven, CT, 06520-8059, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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Liu B, Hood JD, Kolawole EM, Woodruff DM, Vignali DA, Bettini M, Evavold BD. A Hybrid Insulin Epitope Maintains High 2D Affinity for Diabetogenic T Cells in the Periphery. Diabetes 2020; 69:381-391. [PMID: 31806623 PMCID: PMC7034185 DOI: 10.2337/db19-0399] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 11/26/2019] [Indexed: 12/20/2022]
Abstract
β-Cell antigen recognition by autoreactive T cells is essential in type 1 diabetes (T1D) pathogenesis. Recently, insulin hybrid peptides (HIPs) were identified as strong agonists for CD4 diabetogenic T cells. Here, using BDC2.5 transgenic and NOD mice, we investigated T-cell recognition of the HIP2.5 epitope, which is a fusion of insulin C-peptide and chromogranin A (ChgA) fragments, and compared it with the WE14 and ChgA29 -42 epitopes. We measured in situ two-dimensional affinity on individual live T cells from thymus, spleen, pancreatic lymph nodes, and islets before and after diabetes. Although preselection BDC2.5 thymocytes possess higher affinity than splenic BDC2.5 T cells for all three epitopes, peripheral splenic T cells maintained high affinity only to the HIP2.5 epitope. In polyclonal NOD mice, a high frequency (∼40%) of HIP2.5-specific islet T cells were identified at both prediabetic and diabetic stages comprising two distinct high- and low-affinity populations that differed in affinity by 100-fold. This high frequency of high- and low-affinity HIP2.5 T cells in the islets potentially represents a major risk factor in diabetes pathogenesis.
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Affiliation(s)
- Baoyu Liu
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT
| | - Jennifer D Hood
- Department of Microbiology and Immunology, Emory University, Atlanta, GA
| | - Elizabeth M Kolawole
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT
| | | | - Dario A Vignali
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Maria Bettini
- Department of Pediatric Diabetes and Endocrinology, Baylor College of Medicine, Houston, TX
| | - Brian D Evavold
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT
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Soultanova A, Voigt A, Chubanov V, Gudermann T, Meyerhof W, Boehm U, Kummer W. Cholinergic chemosensory cells of the thymic medulla express the bitter receptor Tas2r131. Int Immunopharmacol 2015; 29:143-7. [PMID: 26102274 DOI: 10.1016/j.intimp.2015.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 06/02/2015] [Indexed: 12/14/2022]
Abstract
The thymus is the site of T cell maturation which includes positive selection in the cortex and negative selection in the medulla. Acetylcholine is locally produced in the thymus and cholinergic signaling influences the T cell development. We recently described a distinct subset of medullary epithelial cells in the murine thymus which express the acetylcholine-synthesizing enzyme choline acetyltransferase (ChAT) and components of the canonical taste transduction cascade, i.e. transient receptor potential melastatin-like subtype 5 channel (TRPM5), phospholipase Cβ(2), and Gα-gustducin. Such a chemical phenotype is characteristic for chemosensory cells of mucosal surfaces which utilize bitter receptors for detection of potentially hazardous compounds and cholinergic signaling to initiate avoidance reflexes. We here demonstrate mRNA expression of bitter receptors Tas2r105, Tas2r108, and Tas2r131 in the murine thymus. Using a Tas2r131-tauGFP reporter mouse we localized the expression of this receptor to cholinergic cells expressing the downstream elements of the taste transduction pathway. These cells are distinct from the medullary thymic epithelial cells which promiscuously express tissue-restricted self-antigens during the process of negative selection, since double-labeling immunofluorescence showed no colocalization of autoimmune regulator (AIRE), the key mediator of negative selection, and TRPM5. These data demonstrate the presence of bitter taste-sensing signaling in cholinergic epithelial cells in the thymic medulla and opens a discussion as to what is the physiological role of this pathway.
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Affiliation(s)
- Aichurek Soultanova
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, German Center for Lung Research, Giessen, Germany.
| | - Anja Voigt
- Department of Molecular Genetics, German Institute of Human Nutrition, Potsdam Rehbruecke, Nuthetal, Germany
| | - Vladimir Chubanov
- Walter-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, Munich, Germany
| | - Thomas Gudermann
- Walter-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilian-University, Munich, Germany
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition, Potsdam Rehbruecke, Nuthetal, Germany
| | - Ulrich Boehm
- Department of Pharmacology and Toxicology, University of Saarland School of Medicine, Homburg, Germany
| | - Wolfgang Kummer
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, German Center for Lung Research, Giessen, Germany
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Cholinergic epithelial cell with chemosensory traits in murine thymic medulla. Cell Tissue Res 2014; 358:737-48. [PMID: 25300645 PMCID: PMC4233111 DOI: 10.1007/s00441-014-2002-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 09/04/2014] [Indexed: 12/17/2022]
Abstract
Specialized epithelial cells with a tuft of apical microvilli (“brush cells”) sense luminal content and initiate protective reflexes in response to potentially harmful substances. They utilize the canonical taste transduction cascade to detect “bitter” substances such as bacterial quorum-sensing molecules. In the respiratory tract, most of these cells are cholinergic and are approached by cholinoceptive sensory nerve fibers. Utilizing two different reporter mouse strains for the expression of choline acetyltransferase (ChAT), we observed intense labeling of a subset of thymic medullary cells. ChAT expression was confirmed by in situ hybridization. These cells showed expression of villin, a brush cell marker protein, and ultrastructurally exhibited lateral microvilli. They did not express neuroendocrine (chromogranin A, PGP9.5) or thymocyte (CD3) markers but rather thymic epithelial (CK8, CK18) markers and were immunoreactive for components of the taste transduction cascade such as Gα-gustducin, transient receptor potential melastatin-like subtype 5 channel (TRPM5), and phospholipase Cβ2. Reverse transcription and polymerase chain reaction confirmed the expression of Gα-gustducin, TRPM5, and phospholipase Cβ2. Thymic “cholinergic chemosensory cells” were often in direct contact with medullary epithelial cells expressing the nicotinic acetylcholine receptor subunit α3. These cells have recently been identified as terminally differentiated epithelial cells (Hassall’s corpuscle-like structures in mice). Contacts with nerve fibers (identified by PGP9.5 and CGRP antibodies), however, were not observed. Our data identify, in the thymus, a previously unrecognized presumptive chemosensitive cell that probably utilizes acetylcholine for paracrine signaling. This cell might participate in intrathymic infection-sensing mechanisms.
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