Quasi-Normal Cornified Cell Envelopes in Loricrin Knockout Mice Imply the Existence of a Loricrin Backup System
| Autor: | Elisabeth Scharer, Michal Jarnik, Donnie S. Bundman, Dennis R. Roop, Pierre A. de Viragh, Alasdair C. Steven, Martha N. Simon |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Immunoelectron microscopy
Dermatology Biology Cytoplasmic Granules Biochemistry Mice 030207 dermatology & venereal diseases 03 medical and health sciences Immunolabeling 0302 clinical medicine Cornified Envelope Proline-Rich Proteins Reference Values immunoelectron microscopy medicine Animals Amino Acids Molecular Biology 030304 developmental biology Mice Knockout 0303 health sciences Corneocyte integumentary system Stomach Membrane Proteins Proteins Epithelial Cells Cell Biology small proline-rich proteins terminal differentiation epidermal keratinocytes Cell biology Microscopy Electron medicine.anatomical_structure Epidermal Cells Cytoplasm scanning transmission electron microscopy Loricrin Epidermis Cell envelope Keratinocyte |
| Zdroj: | Journal of Investigative Dermatology. 118:102-109 |
| ISSN: | 0022-202X |
| Popis: | The cornified cell envelope, a lipoprotein layer that assembles at the surface of terminally differentiated keratinocytes, is a resilient structure on account of covalent crosslinking of its constituent proteins, principally loricrin, which accounts for up to 60%-80% of total protein. Despite the importance of the cell envelope as a protective barrier, knocking out the loricrin gene in mice results in only mild syndromes. We have investigated the epidermis and forestomach epithelium of these mice by electron microscopy. In both tissues, corneocytes have normal-looking cell envelopes, despite the absence of loricrin, which was confirmed by immunolabeling, and the absence of the distinctive loricrin-containing keratohyalin granules (L-granules). Isolated cell envelopes were normal in thickness (approximately 15 nm) and mass per unit area (approximately 7.3 kDa per nm2); however, metal shadowing revealed an altered substructure on their cytoplasmic surface. Their amino acid compositions indicate altered protein compositions. Analysis of these data implies that the epidermal cell envelopes have elevated levels of the small proline-rich proteins, and cell envelopes of both kinds contain other protein(s) that, like loricrin, are rich in glycine and serine. These observations imply that, in the absence of loricrin, the mechanisms that govern cell envelope assembly function normally but employ different building-blocks. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|