title: Ultrastructural immunocytochemistry for the central region of keratin associated-beta-proteins (beta-keratins) shows the epitope is constantly expressed in reptilian epidermis.
abstract: The presence of beta-proteins containing a core-box region in specific regions of reptilian epidermis has been studied by immunological methods. Alpha-keratins are detected by the antibody AK2 that recognizes a sequence toward the C-terminal of acidic alpha-keratins of 48-52kDa. Beta-proteins are recognized by an antibody directed to the core-box region specific for these proteins of 18-37kDa. The AK2 antibody labels with variable intensity alpha-keratin bundles in basal and suprabasal keratinocytes in the epidermis of representative species of reptiles but immunolabeling decreases or disappears in pre-corneous and corneous cells. As opposite, the core-box antibody only labels with variable intensity the dense beta-corneous material formed in pre-corneous and corneous layers of crocodilian and turtle epidermis. In lepidosaurian epidermis the core-box antibody labels the beta-layer while the mesos and alpha-layers are poorly or not labeled. The immunological evidence indicates that beta-proteins are synthesized in the upper spinosus and pre-corneous layers of the epidermis and replace or mask the initial alpha-keratin framework present in keratinocytes as they differentiate into cells of the beta-layer. In the specialized pad lamellae of gecko and anoline lizards charged beta-proteins accumulate in the adhesive setae and may affect the mechanism of adhesion that allows these lizards to walk vertical surfaces. The addition of beta-proteins to the alpha-keratins in upper cell layers of the epidermis recalls the process of cornification of mammalian epidermis where specific keratin-associated proteins (involucrin, loricrin and filaggrin) associate with the keratin framework in terminally differentiating keratinocytes of the stratum corneum.
authors.affiliation: Comparative Histolab and Dipartimento di Biologia, University of Bologna, Bologna, Italy. lorenzo.alibardi@unibo.it
authors.forename: L
authors.initials: L
authors.lastname: Alibardi
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002454:Cell Differentiation; D004817:Epidermis / Q000737:chemistry / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology / Q000276:immunology; D008116:Lizards; D058618:Sensilla / Q000737:chemistry / Q000648:ultrastructure; D053800:beta-Keratins / Q000096:biosynthesis* / Q000276:immunology / Q000648:ultrastructure*
chemical_list: D000939:Epitopes; D053800:beta-Keratins