Cloning and characterization of scale β‐keratins in the differentiating epidermis of geckoes show they are glycine‐proline‐serine–rich proteins with a central motif homologous to avian β‐keratins

Valle, Luisa Dalla; Nardi, Alessia; Toffolo, Vania; Niero, Cristiana; Toni, Mattia; Alibardi, Lorenzo

doi:10.1002/dvdy.21022

Cited by 63 publications

(73 citation statements)

References 31 publications

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“…The present immunoblotting and immunolocalization survey confirms that the deduced epitopes through molecular biology methods (Dalla Valle et al,2005,2007a,b,2008,2009,2010; Hallahan et al,2008; Alibardi et al,2009; Ye et al,2010) are present in alpha‐keratins and beta‐proteins of the epidermis in chelonians, crocodilians, and lepidosaurians. The specificity for the epitope recognition through the employed antibodies is demonstrated by the disappearing of immunolabeled bands after preabsorbing with the peptide (Figs.…”

Section: Discussionsupporting

confidence: 80%

“…Their genes are activated only in suprabasal or precorneous keratinocytes as it is typical for specialized corneous proteins. The gene structure of these proteins (Dalla Valle et al,2005,2007a,b;2008,2010) is similar to that of avian genes for feather or phi‐keratins (Brush,1983, Gregg and Rogers,1986). Furthermore, their initial basic pI suggests that they are complementary proteins to the acidic‐neutral alpha‐keratins present in reptiles where basic alpha‐keratins are almost absent (Alibardi and Toni,2006, Toni et al, 2007).…”

Section: Introductionmentioning

confidence: 83%

“…The sequencing of above 110 KAbetaPs in different lepidosaurians, crocodilians, and turtles (Dalla Valle et al,2005,2007a,b,2008,2009a,b,2010; Hallahan et al2008; Ye et al,2010) and of 10 alpha‐keratins (Hallahan et al,2008; Eckhart et al, 2008; Dalla Valle et al, 2010, and database data) has allowed the selection of specific epitopes for both alpha‐ and beta‐proteins to make epitope‐specific reptilian antibodies. Aside the variable and cys‐rich N‐ and C‐terminals for beta‐proteins, three main regions characteristics for lepidosaurian, turtle, and crocodilians, have been identified for the precore‐box regions of beta‐proteins (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Cornification in reptilian epidermis occurs through the deposition of keratin‐associated beta‐proteins (beta‐keratins) onto a scaffold of intermediate filament keratins

Alibardi

2012

Journal of Morphology

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The isolation of genes for alpha-keratins and keratin-associated beta-proteins (formerly beta-keratins) has allowed the production of epitope-specific antibodies for localizing these proteins during the process of cornification epidermis of reptilian sauropsids. The antibodies are directed toward proteins in the alpha-keratin range (40-70 kDa) or beta-protein range (10-30 kDa) of most reptilian sauropsids. The ultrastructural immunogold study shows the localization of acidic alpha-proteins in suprabasal and precorneous epidermal layers in lizard, snake, tuatara, crocodile, and turtle while keratin-associated beta-proteins are localized in precorneous and corneous layers. This late activation of the synthesis of keratin-associated beta-proteins is typical for keratin-associated and corneous proteins in mammalian epidermis (involucrin, filaggrin, loricrin) or hair (tyrosine-rich or sulfur-rich proteins). In turtles and crocodilians epidermis, keratin-associated beta-proteins are synthesized in upper spinosus and precorneous layers and accumulate in the corneous layer. The complex stratification of lepidosaurian epidermis derives from the deposition of specific glycine-rich versus cysteine-glycine-rich keratin-associated beta-proteins in cells sequentially produced from the basal layer and not from the alternation of beta- with alpha-keratins. The process gives rise to Oberhäutchen, beta-, mesos-, and alpha-layers during the shedding cycle of lizards and snakes. Differently from fish, amphibian, and mammalian keratin-associated proteins (KAPs) of the epidermis, the keratin-associated beta-proteins of sauropsids are capable to form filaments of 3-4 nm which give rise to an X-ray beta-pattern as a consequence of the presence of a beta-pleated central region of high homology, which seems to be absent in KAPs of the other vertebrates.

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Section: Discussionsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Cornification in reptilian epidermis occurs through the deposition of keratin‐associated beta‐proteins (beta‐keratins) onto a scaffold of intermediate filament keratins

Alibardi

2012

Journal of Morphology

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“…Recent molecular biology and proteomic studies have sequenced some genes and proteins as β-keratins (Dalla Valle et al ., 2005, 2007). These molecules comprise glycine-proline-rich and cystein-proline-rich proteins of 13–19 kDa.…”

Section: Evo-devomentioning

confidence: 99%

Reptile scale paradigm: Evo-Devo, pattern formation and regeneration

Chang

Wu²,

Baker³

et al. 2009

Int. J. Dev. Biol.

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141

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The purpose of this perspective is to highlight the merit of the reptile integument as an experimental model. Reptiles represent the first amniotes. From stem reptiles, extant reptiles, birds and mammals have evolved. Mammal hairs and feathers evolved from Therapsid and Sauropsid reptiles, respectively. The early reptilian integument had to adapt to the challenges of terrestrial life, developing a multi-layered stratum corneum capable of barrier function and ultraviolet protection. For better mechanical protection, diverse reptilian scale types have evolved. The evolution of endothermy has driven the convergent evolution of hair and feather follicles: both form multiple localized growth units with stem cells and transient amplifying cells protected in the proximal follicle. This topological arrangement allows them to elongate, molt and regenerate without structural constraints. Another unique feature of reptile skin is the exquisite arrangement of scales and pigment patterns, making them testable models for mechanisms of pattern formation. Since they face the constant threat of damage on land, different strategies were developed to accommodate skin homeostasis and regeneration. Temporally, they can be under continuous renewal or sloughing cycles. Spatially, they can be diffuse or form discrete localized growth units (follicles). To understand how gene regulatory networks evolved to produce increasingly complex ectodermal organs, we have to study how prototypic scale-forming pathways in reptiles are modulated to produce appendage novelties. Despite the fact that there are numerous studies of reptile scales, molecular analyses have lagged behind. Here, we underscore how further development of this novel experimental model will be valuable in filling the gaps of our understanding of the Evo-Devo of amniote integuments.

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“…More recent studies on the proteins and genes of reptilian beta‐keratins (Dalla Valle et al, , ,b, ,b; Hallahan et al, ) have indicated that these small proteins are not keratins since they are not intermediate filament proteins. These small proteins correspond to specific KAPs evolved in sauropsids that are, case so far unique among vertebrates, capable to form themselves filamentous structures (Fraser et al, ; Brush, ; Fraser and Parry, ) that mix with those of intermediate filaments (Alibardi and Toni, , ; Alibardi et al, , ; Toni et al, ).…”

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confidence: 99%

Distribution of Specific Keratin‐Associated Beta‐Proteins (Beta‐Keratins) in the Epidermis of the Lizard Anolis carolinensis Helps to Clarify the Process of Cornification in Lepidosaurians

2012

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The epidermis of different scales in the lizard Anolis carolinensis expresses specific keratin‐associated beta‐proteins (beta‐keratins). In order to localize the sites of accumulation of different beta‐proteins, we have utilized antibodies directed against representative members of the main families of beta‐proteins, the glycine‐rich (HgG5), glycine–cysteine rich (HgGC3), glycine–cysteine medium‐rich (HgGC10), and cysteine‐rich (HgC1) beta‐proteins. Immunoblotting and immunocytochemical controls confirm the specificity of the antibodies made against these proteins. Light and ultrastructural immunocytochemistry shows that the glycine‐rich protein HgG5 is present in beta‐layers of different body scales but is scarce in the oberhautchen and claws, and is absent in alpha‐layers and adhesive setae. The cysteine–glycine‐rich protein HgGC3 is low to absent in the oberhautchen, beta‐layer, and mesos‐layer but increases in alpha‐layers. This beta‐protein is low in claws where it is likely associated with the hard alpha‐keratins previously studied in this lizard. The glycine–cysteine medium‐rich HgGC10 protein is low in the beta‐layer, higher in alpha‐layers, and in the oberhautchen. This protein forms a major component of setal proteins including those of the adhesive spatula that allow this lizard to stick on vertical surfaces. HgC1 is poorly localized in most epidermis analyzed including adhesive setae and claws and appears as a minor component of the alpha‐layers. In conclusion, the present study suggests that beta‐ and alpha‐layers of lizard epidermis represent regions with different accumulation of glycine‐rich proteins (mainly for mechanical resistance and hydrophobicity in the beta‐layer) or cysteine–glycine‐rich proteins (for both resistance and elasticity in both alpha‐ and beta‐layers). J. Exp. Zool. (Mol. Dev. Evol.) 318B:388‐403, 2012. © 2012 Wiley Periodicals, Inc.

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Cloning and characterization of scale β‐keratins in the differentiating epidermis of geckoes show they are glycine‐proline‐serine–rich proteins with a central motif homologous to avian β‐keratins

Cited by 63 publications

References 31 publications

Cornification in reptilian epidermis occurs through the deposition of keratin‐associated beta‐proteins (beta‐keratins) onto a scaffold of intermediate filament keratins

Cornification in reptilian epidermis occurs through the deposition of keratin‐associated beta‐proteins (beta‐keratins) onto a scaffold of intermediate filament keratins

Reptile scale paradigm: Evo-Devo, pattern formation and regeneration

Distribution of Specific Keratin‐Associated Beta‐Proteins (Beta‐Keratins) in the Epidermis of the Lizard Anolis carolinensis Helps to Clarify the Process of Cornification in Lepidosaurians

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