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Immunolocalization of alpha-keratins and associated beta-proteins in lizard epidermis shows that acidic keratins mix with basic keratin-associated beta-proteins

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Abstract

The differentiation of the corneous layers of lizard epidermis has been analyzed by ultrastructural immunocytochemistry using specific antibodies against alpha-keratins and keratin associated beta-proteins (KAbetaPs, formerly indicated as beta-keratins). Both beta-cells and alpha-cells of the corneous layer derive from the same germinal layer. An acidic type I alpha-keratin is present in basal and suprabasal layers, early differentiating clear, oberhautchen, and beta-cells. Type I keratin apparently disappears in differentiated beta- and alpha-layers of the mature corneous layers. Conversely, a basic type II alpha-keratin rich in glycine is absent or very scarce in basal and suprabasal layers and this keratin likely does not pair with type I keratin to form intermediate filaments but is weakly detected in the pre-corneous and corneous alpha-layer. Single and double labeling experiments show that in differentiating beta-cells, basic KAbetaPs are added and replace type-I keratin to form the hard beta-layer. Epidermal alpha-keratins contain scarce cysteine (0.2–1.4 %) that instead represents 4–19 % of amino acids present in KAbetaPs. Possible chemical bonds formed between alpha-keratins and KAbetaPs may derive from electrostatic interactions in addition to cross-linking through disulphide bonds. Both the high content in glycine of keratins and KAbetaPs may also contribute to increase the hydrophobicy of the beta- and alpha-layers and the resistance of the corneous layer. The increase of gly-rich KAbetaPs amount and the bonds to the framework of alpha-keratins give rise to the inflexible beta-layer while the cys-rich KAbetaPs produce a pliable alpha-layer.

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References

  • Alibardi L (2003) Adaptation to the land: The skin of reptiles in comparison to that of amphibians and endotherm amniotes. J Exp Zool B 298:12–41

    Article  Google Scholar 

  • Alibardi L (2013a) Cornification in reptilian epidermis occurs through the deposition of keratin associated beta proteins (beta-keratins) onto a scaffold of intermediate filament keratins. J Morphol 274:175–193

    Article  CAS  PubMed  Google Scholar 

  • Alibardi L (2013b) Comparative immunolocalization of keratin-associated beta-proteins (beta-keratins) supports a new explanation for the cyclical process of keratinocyte differentiation in lizard epidermis. Acta Zool. doi:10.1111/azo.12030

  • Alibardi L (2013c) Immunolocalization of specific keratin associated beta-proteins (beta-keratins) in the adhesive setae of Gekko gecko. Tiss Cell 45(4):231–40

    Article  CAS  Google Scholar 

  • Alibardi L (2013d) Immunolocalization of keratin associated beta-proteins (beta-keratins) in the regenerating lizard epidermis indicates a new process for the differentiation of the epidermis in lepidosaurians. J Morphol 273:1272–1279

    Article  Google Scholar 

  • Alibardi L, Toni M (2006) Cytochemical, biochemical and molecular aspects of the process of keratinization in the epidermis of reptilian scales. Prog Histoch Cytoch 40:73–134

    Article  CAS  Google Scholar 

  • Alibardi L, Toni M, Dalla Valle L (2007) Review. Hard keratins in reptilian epidermis in comparison to those of birds and mammals. Exp Dermatol 16:961–976

    Article  CAS  PubMed  Google Scholar 

  • Alibardi L, Dalla Valle L, Nardi A, Toni M (2009) Evolution of hard proteins in the sauropsid integument in relation to the cornification of skin derivatives in amniotes. J Anat 214:560–586

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Alibardi L, Segalla A, Dalla Valle L (2012) Distribution of specific keratin associated beta-proteins (beta-keratins) in the epidermis of the lizard Anolis carolinensis clarifies the process of cornification in lepidosaurians. J Exp Zool 318B:388–403

    Article  Google Scholar 

  • Baden HP, Maderson PF (1970) Morphological and biophysical identification of fibrous proteins in the amniote epidermis. J Exp Zool 174:225–232

    Article  CAS  PubMed  Google Scholar 

  • Bragulla HH, Homberger DG (2009) Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia. J Anat 214:516–559

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Coulombe PA, Omary MB (2002) 'Hard' and 'soft' principles defining the structure, function and regulation of keratin intermediate filaments. Curr Opin Cell Biol 14:110–122

    Article  CAS  PubMed  Google Scholar 

  • Dalla Valle L, Nardi A, Bonazza G, Zuccal C, Emeera D, Alibardi L (2010) Forty keratin-associated β–proteins (β-keratins) form the hard layers of scales, claws and adhesive pads in the green anole lizard, Anolis carolinensis. J Exp Zool 314B:11–32

    Article  CAS  Google Scholar 

  • Dalla Valle L, Michieli F, Benato F, Skobo T, Alibardi L, (2013) Molecular characterization of alpha-keratins in comparison to associated beta-proteins in soft-shelled and hard-shelled turtles produced during the process of epidermal differentiation. J Exp Zool 320B:428–441

  • Eckhart L, Dalla Valle L, Jaeger K, Ballaun C, Szabo S, Nardi A, Buchberger M, Hermann M, Alibardi L, Tschachler E (2008) Identification of reptilian genes encoding hair keratin-like proteins suggests a new scenario for the evolutionary origin of hair. Proc Natl Acad Sci USA 105:18419–18423

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Fraser RDB, Parry DAD (2008) Molecular packing in the feather keratin filament. J Struct Biol 162:1–13

    Article  CAS  PubMed  Google Scholar 

  • Fraser RDB, Parry DAD (2011) The structural basis of the filament-matrix texture in the avian/reptilian group of hard beta-keratins. J Struct Biol 173:391–405

    Article  CAS  PubMed  Google Scholar 

  • Fuchs E, Marchuk D (1983) Type I and type II keratins have evolved from lower eukaryotes to form the epidermal intermediate filaments in mammalian skin. Proc Natl Acad Sci USA 80:5857–5861

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Hallahan DL, Keiper-Hrynko NM, Ganzke TS, Toni M, Dalla Valle L, Alibardi L (2008) Gene expression in analysis of adhesive pads of gecko digits shows they mainly code for significant production of cysteine-rich and glycine-rich beta-keratins. J Exp Zool 312B:58–73

    Article  Google Scholar 

  • Kirfel J, Magin TM, Reichelt J (2003) Keratins: A structural scaffold with emerging functions. Cell Mot Life Sci 60:56–71

    Article  CAS  Google Scholar 

  • Kreplak A, Franbourg A, Briki F, Leroy F, Dalle D, Doucet J (2002) A new deformation model of hard α-fibers at the nanometer scale: Implications for hard α-keratin intermediate filaments mechanical properties. Biophys J 82:2265–2274

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Landmann L (1986) The skin of reptiles: Epidermis and dermis. In: Bereither-Hahn J, Matoltsy G, Sylvia-Richards K (eds) Biology of the integument, Vertebrate. Springer Verlag, New York, pp 150–187

    Chapter  Google Scholar 

  • Maderson PFA (1972) When? Why? and How?: Some speculations on the evolution of the vertebrate integument. Amer Zool 12:159–171

    Article  Google Scholar 

  • Maderson PF (1985) Some developmental problems of the reptilian integument. In: Gans C, Billett F, Maderson PF (eds) Biology of reptilia: Development. Wiley, New York, pp 525–598

    Google Scholar 

  • Maderson PFA, Rabinowitz T, Tandler B, Alibardi L (1998) Ultrastructural contributions to an understanding of the cellular mechanisms involved in lizard skin shedding with comments on the function and evolution of a unique lepidosaurian phenomenon. J Morphol 236:1–24

    Article  Google Scholar 

  • O'Guin MW, Galvin S, Schermer A, Sun TT (1987) Pattern of keratin expression define distinct pathways of epithelial development and differentiation. In: Sawyer R.H. editor. Topics in Developmental Biology 22:97–125

    Article  Google Scholar 

  • Sawyer RH, Glenn TC, French JO, Mays B, Shames RB, Barnes GL, Rhodes W, Ishikawa Y (2000) The expression of beta (β) keratins in the epidermal appendages of reptiles and birds. Amer Zool 40:530–539

    CAS  Google Scholar 

  • Scala C, Cenacchi G, Ferrari C, Pasquinelli G, Preda P, Manara G (1992) A new acrylic resin formulation: A useful tool for histological, ultrastructural, and immunocytochemical investigations. J Histochem Cytochem 40:1799–1804

    Article  CAS  PubMed  Google Scholar 

  • Steinert PM, Freedberg IM (1991) Molecular and cellular biology of keratins. In: Goldsmith LA (ed) Physiology, biochemistry, and molecular biology of the skin. Oxford University Press, New York, pp 113–147

    Google Scholar 

  • Sun TT, Eichner R, Nelson WG, Scheffer-Tseng BA, Weiss RA, Jarvinen M, Woodcock-Mitchell J (1983) Keratin classes: Molecular markers for different types of epithelial differentiation. J Inv Dermatol 81:109s–115s

    Article  CAS  Google Scholar 

  • Sybert VP, Dale BA, Holbrook KA (1985) Ichthyosis vulgaris: Identification of a defect in synthesis of filaggrin correlated with an absence of keratohyalin granules. J Invest Dermatol 84:191–194

    Article  CAS  PubMed  Google Scholar 

  • Toni M, Valle LD, Alibardi L (2007) Hard (Beta-)keratins in the epidermis of reptiles: Composition, sequence, and molecular organization. J Proteome Res 6:3377–3392

    Article  CAS  PubMed  Google Scholar 

  • Vandebergh W, Bossuyt F (2012) Radiation and functional diversification of alpha keratins during early vertebrate evolution. Mol Biol Evol 29:995–1004

    Article  CAS  PubMed  Google Scholar 

  • Wyld JA, Brush AH (1979) The molecular heterogeneity and diversity of reptilian keratins. J Mol Evol 12:331–347

    Article  CAS  PubMed  Google Scholar 

  • Wyld JA, Brush AH (1983) Keratin diversity in the reptilian epidermis. J Exp Zool 225:387–396

    Article  CAS  Google Scholar 

Download references

Acknowledgments

The study was in part self-supported (Comparative Histolab) and also with a Grant from the Italian Ministry of Education and Scientific Research (Grant 2008 AXS E-002). The electrophoretic separation and Western blotting were carried on at the Proteome Service Facility in the Department of Biology, University of Bologna (Dr. F. Boschetti).

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  1. Comparative Histolab and Dipartimento di Biologia, Geologia e Scienze Ambientali, University of Bologna, Bologna, Italy

    Lorenzo Alibardi

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  1. Lorenzo Alibardi
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Correspondence to Lorenzo Alibardi.

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Handling Editor: Pavel Dráber

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Alibardi, L. Immunolocalization of alpha-keratins and associated beta-proteins in lizard epidermis shows that acidic keratins mix with basic keratin-associated beta-proteins. Protoplasma 251, 827–837 (2014). https://doi.org/10.1007/s00709-013-0585-9

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