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Lomakin IB, Ho M, Bunick CG. Unveiling the secrets of vimentin filament architecture relevant to human disease. Nat Struct Mol Biol 2024; 31:849-851. [PMID: 38684931 DOI: 10.1038/s41594-024-01301-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Affiliation(s)
- Ivan B Lomakin
- Department of Dermatology, Yale School of Medicine, New Haven, CT, USA
| | - Minh Ho
- Department of Dermatology, Yale School of Medicine, New Haven, CT, USA
| | - Christopher G Bunick
- Department of Dermatology, Yale School of Medicine, New Haven, CT, USA.
- Program in Translational Biomedicine, Yale University, New Haven, CT, USA.
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Yu B, Kong D, Cheng C, Xiang D, Cao L, Liu Y, He Y. Assembly and recognition of keratins: A structural perspective. Semin Cell Dev Biol 2021; 128:80-89. [PMID: 34654627 DOI: 10.1016/j.semcdb.2021.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 09/22/2021] [Accepted: 09/29/2021] [Indexed: 12/21/2022]
Abstract
Keratins are one of the major components of cytoskeletal network and assemble into fibrous structures named intermediate filaments (IFs), which are important for maintaining the mechanical properties of cells and tissues. Over the past decades, evidence has shown that the functions of keratins go beyond providing mechanical support for cells, they interact with multiple cellular components and are widely involved in the pathways of cell proliferation, differentiation, motility and death. However, the structural details of keratins and IFs are largely missing and many questions remain regarding the mechanisms of keratin assembly and recognition. Here we briefly review the current structural models and assembly of keratins as well as the interactions of keratins with the binding partners, which may provide a structural view for understanding the mechanisms of keratins in the biological activities and the related diseases.
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Affiliation(s)
- Bowen Yu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Immunology, School of Basic Medical Sciences, Weifang Medical University, Weifang, China
| | - Dandan Kong
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Cheng
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dongxi Xiang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Biliary-Pancreatic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Longxing Cao
- School of Life Science, Westlake University, Hangzhou, Zhejiang, China
| | - Yingbin Liu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Biliary-Pancreatic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yongning He
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Biliary-Pancreatic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
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3
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Pan CY, Chou CC. Molecular origin of the effects of mutation on the structure and mechanical properties of human epithelial keratin K5/K14. J Mech Behav Biomed Mater 2021; 124:104798. [PMID: 34509171 DOI: 10.1016/j.jmbbm.2021.104798] [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: 05/07/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 01/30/2023]
Abstract
Epithelial keratin, a type of intermediate filament (IF) protein, is one of the key components in maintaining the stability of the cell nucleus in the epidermis of the skin, the largest organ in the human body. It absorbs water and withstands external pressure, affecting the structural stability and mechanical properties of the skin. Epidermolysis bullosa simplex (EBS) is a rare genetic skin disease related to genetic mutations in epithelial keratin K5/K14. The resulting structural defects can cause keratinocytes in the basal layer to become fragile and rupture when subjected to mechanical stress. Its pathological feature is that the skin and mucous membranes are extremely fragile, and wounds and blisters occur under even slight external force. In this study, we focused on the amino acid sequence of the wild-type human keratin K5/K14 and sequences with point mutations, beginning with a full atomistic model of the K5/K14 heterodimer and proceeding to the higher hierarchical structure of the tetramer model. For the heterodimer, the structures of the wild type and the mutants share a high degree of similarity, and the helical structure is preserved. Then, based on the heterodimer model, we considered the keratin tetramer model with the ID1 contact from previous experimental observations. Our results suggested that in the wild-type tetramer, the hydrogen bonds formed in the middle and contact regions provide extra stability to tetramer 2B-2B interactions during IF assembly. The probabilities of hydrogen bond formation are lower in the mutant tetramers than in the wild-type tetramer in the contact region; the point mutations do not necessarily affect the structure for dimer formation, but changes in the interactions of amino acids may affect the higher-order assembly of IFs. We observed that the structures of the tetramers with point mutations were loosely stacked, and the mechanical properties were weaker than those of the wild-type tetramer. We further compared our results with the latest experimental measurements and discussed the relationship between the genotype of EBS disease and the atomic-level mutated structures. The atomistic model allowed us to study point mutations at the molecular level. The results can be further applied to reveal the effect of point mutations on EBS disease.
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Affiliation(s)
- Chien-Yu Pan
- Institute of Applied Mechanics, National Taiwan University, Taipei City, Taiwan
| | - Chia-Ching Chou
- Institute of Applied Mechanics, National Taiwan University, Taipei City, Taiwan.
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Wu TT, Eldirany SA, Bunick CG, Teng JMC. Genotype-structurotype-phenotype correlations in pachyonychia congenita patients. J Invest Dermatol 2021; 141:2876-2884.e4. [PMID: 34116063 DOI: 10.1016/j.jid.2021.03.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 03/09/2021] [Accepted: 03/21/2021] [Indexed: 01/16/2023]
Abstract
Pachyonychia congenita (PC) is a genetic disorder of keratin that presents with nail dystrophy, painful palmoplantar keratoderma, and other clinical manifestations. We investigated genotype-structurotype-phenotype correlations seen with mutations in keratin genes (KRT6A, KRT6B, KRT6C, KRT16, KRT17) and utilized protein structure modeling of high frequency mutations to examine the functional importance of keratin structural domains in PC pathogenesis. Participants of the International PC Research Registry underwent genetic testing and completed a standardized survey on their symptoms. Our results support prior reports associating oral leukokeratosis with KRT6A mutations, and cutaneous cysts, follicular hyperkeratosis, and natal teeth with KRT17 mutations. Painful keratoderma was prominent with KRT6A and KRT16 mutations. Nail involvement was most common in KRT6A and least common in KRT6C patients. Across keratin subtypes, patients with coil 2B mutations had greatest impairment in ambulation, and patients with coil 1A mutations reported more emotional issues. Molecular modeling demonstrated that hotspot missense mutations in PC largely disrupted hydrophobic interactions or surface charge. The former may destabilize keratin dimers/tetramers, while the latter likely interferes with higher-order keratin filament formation. Understanding pathologic alterations in keratin structure improves our knowledge of how PC genotype correlates with clinical phenotype, advancing insight into disease pathogenesis and therapeutic development.
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Affiliation(s)
- Tiffany T Wu
- Department of Dermatology, Stanford University, Palo Alto, CA
| | | | | | - Joyce M C Teng
- Department of Dermatology, Stanford University, Palo Alto, CA.
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Eldirany SA, Lomakin IB, Ho M, Bunick CG. Recent insight into intermediate filament structure. Curr Opin Cell Biol 2020; 68:132-143. [PMID: 33190098 DOI: 10.1016/j.ceb.2020.10.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/22/2020] [Accepted: 10/05/2020] [Indexed: 12/17/2022]
Abstract
Intermediate filaments (IFs) are key players in multiple cellular processes throughout human tissues. Their biochemical and structural properties are important for understanding filament assembly mechanisms, for interactions between IFs and binding partners, and for developing pharmacological agents that target IFs. IF proteins share a conserved coiled-coil central-rod domain flanked by variable N-terminal 'head' and C-terminal 'tail' domains. There have been several recent advances in our understanding of IF structure from the study of keratins, glial fibrillary acidic protein, and lamin. These include discoveries of (i) a knob-pocket tetramer assembly mechanism in coil 1B; (ii) a lamin-specific coil 1B insert providing a one-half superhelix turn; (iii) helical, yet flexible, linkers within the rod domain; and (iv) the identification of coil 2B residues required for mature filament assembly. Furthermore, the head and tail domains of some IFs contain low-complexity aromatic-rich kinked segments, and structures of IFs with binding partners show electrostatic surfaces are a major contributor to complex formation. These new data advance the connection between IF structure, pathologic mutations, and clinical diseases in humans.
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Affiliation(s)
- Sherif A Eldirany
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA
| | - Ivan B Lomakin
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA
| | - Minh Ho
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA
| | - Christopher G Bunick
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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Molecular Modeling of Pathogenic Mutations in the Keratin 1B Domain. Int J Mol Sci 2020; 21:ijms21186641. [PMID: 32927888 PMCID: PMC7555247 DOI: 10.3390/ijms21186641] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 12/29/2022] Open
Abstract
Keratin intermediate filaments constitute the primary cytoskeletal component of epithelial cells. Numerous human disease phenotypes related to keratin mutation remain mechanistically elusive. Our recent crystal structures of the helix 1B heterotetramer from keratin 1/10 enabled further investigation of the effect of pathologic 1B domain mutations on keratin structure. We used our highest resolution keratin 1B structure as a template for homology-modeling the 1B heterotetramers of keratin 5/14 (associated with blistering skin disorders), keratin 8/18 (associated with liver disease), and keratin 74/28 (associated with hair disorder). Each structure was examined for the molecular alterations caused by incorporating pathogenic 1B keratin mutations. Structural modeling indicated keratin 1B mutations can harm the heterodimer interface (R265PK5, L311RK5, R211PK14, I150VK18), the tetramer interface (F231LK1, F274SK74), or higher-order interactions needed for mature filament formation (S233LK1, L311RK5, Q169EK8, H128LK18). The biochemical changes included altered hydrophobic and electrostatic interactions, and altered surface charge, hydrophobicity or contour. Together, these findings advance the genotype-structurotype-phenotype correlation for keratin-based human diseases.
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