Recurrent functional divergence of early tetrapod keratins in amphibian toe pads and mammalian hair

Vandebergh, Wim; Maex, Margo; Bossuyt, Franky; Bocxlaer, Ines Van

doi:10.1098/rsbl.2013.0051

Cited by 13 publications

(11 citation statements)

References 18 publications

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“…4). In line with results of previous studies 27,28 , we identified Krt24 -like genes but not 1:1 orthologs of Krt24 besides Krt222 in fish and amphibians. In the alligator a Krt24 -like gene is located between Krt222 and Krt10 , and three Krt24 -like genes are present in the platypus, representing basal mammals (Supplementary Tables S1–S7; Suppl.…”

Section: Resultssupporting

confidence: 92%

Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals

Ehrlich

Laggner

Langbein

et al. 2019

Sci Rep

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Keratins are the main cytoskeletal proteins of epithelial cells and changes in the expression of keratins have contributed to the evolutionary adaptation of epithelia to different environments. Keratin K24 was proposed to be a differentiation marker of epidermal keratinocytes but the significance of K24 expression in the epidermis versus other tissues has remained elusive. Here, we show by RT-PCR, western blot, and immunofluorescence analyses that K24 is highly expressed in the epithelium of the cornea whereas its expression levels are significantly lower in other stratified epithelia including in the epidermis. To investigate the evolutionary history of K24, we screened the genome sequences of vertebrates for orthologs of the human KRT24 gene. The results of this comparative genomics study suggested that KRT24 originated in a common ancestor of amniotes and that it was lost independently in three clades of mammals, i.e. camels, cetaceans, and a subclade of pinnipeds comprising eared seals and the walrus. Together, the results of this study identify K24 as component of the cytoskeleton in the human corneal epithelium and reveal previously unknown differences of keratin gene content among mammalian species.

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Section: Resultssupporting

confidence: 92%

Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals

Ehrlich

Laggner

Langbein

et al. 2019

Sci Rep

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“…4 B and C ). Of note, the last two exons of the keratin genes most closely related to KRT10 , that is, KRT12 and KRT24 – KRT28 (Vandebergh and Bossuyt 2012; Vandebergh et al. 2013), are spliced in phase 1, like KRT10x1 .…”

Section: Resultsmentioning

confidence: 99%

“…2018). Together with comparative studies of keratins in phylogenetically diverse vertebrates (Zimek and Weber 2005; Vandebergh and Bossuyt 2012; Vandebergh et al 2013; Greenwold et al. 2014; Wu et al.…”

Section: Discussionmentioning

confidence: 99%

Differential Evolution of the Epidermal Keratin Cytoskeleton in Terrestrial and Aquatic Mammals

Ehrlich

Fischer

Langbein

et al. 2018

Molecular Biology and Evolution

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Keratins are the main intermediate filament proteins of epithelial cells. In keratinocytes of the mammalian epidermis they form a cytoskeleton that resists mechanical stress and thereby are essential for the function of the skin as a barrier against the environment. Here, we performed a comparative genomics study of epidermal keratin genes in terrestrial and fully aquatic mammals to determine adaptations of the epidermal keratin cytoskeleton to different environments. We show that keratins K5 and K14 of the innermost (basal), proliferation-competent layer of the epidermis are conserved in all mammals investigated. In contrast, K1 and K10, which form the main part of the cytoskeleton in the outer (suprabasal) layers of the epidermis of terrestrial mammals, have been lost in whales and dolphins (cetaceans) and in the manatee. Whereas in terrestrial mammalian epidermis K6 and K17 are expressed only upon stress-induced epidermal thickening, high levels of K6 and K17 are consistently present in dolphin skin, indicating constitutive expression and substitution of K1 and K10. K2 and K9, which are expressed in a body site-restricted manner in human and mouse suprabasal epidermis, have been lost not only in cetaceans and manatee but also in some terrestrial mammals. The evolution of alternative splicing of K10 and differentiation-dependent upregulation of K23 have increased the complexity of keratin expression in the epidermis of terrestrial mammals. Taken together, these results reveal evolutionary diversification of the epidermal cytoskeleton in mammals and suggest a complete replacement of the quantitatively predominant epidermal proteins of terrestrial mammals by originally stress-inducible keratins in cetaceans.

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“…the toe pads in frogs and hairs in mammals (Vandebergh et al . ). The Upper Permian coprolitic findings from South Africa and Russia (described herein) possibly provide the first direct evidence of pre‐Mesozoic hairs of non‐mammalian origin.…”

Section: Discussionmentioning

confidence: 97%

Microbiota and food residues including possible evidence of pre-mammalian hair in Upper Permian coprolites from Russia

Bajdek¹,

Qvarnström

Owocki

et al. 2016

LET

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Coprolites (fossil faeces) provide direct evidence on the diet of its producer and unique insights on ancient food webs and ecosystems. We describe the contents of seven coprolites, collected from the Late Permian Vyazniki site of the European part of Russia. Two coprolite morphotypes (A, B) contain remains of putative bacteria, cyanobacteria, fungi, protists, invertebrate eggs, arthropod elements, undigested bone and tooth fragments, fish scales and elongated hair-like structures with hollow interiors. Content, size and shape of the coprolites together with the associated body fossil record suggest that the most probable scat-producers were carnivorous tetrapods; the bone-rich morphotype A reveals short food retention time and a fast metabolism and is therefore assigned to therapsid carnivores whereas morphotype B with rarer and degraded bones are assigned to archosauromorphs or other non-therapsid carnivores. The general coprolite matrix contains abundant micron-sized spheres and thin-walled vesicles which are interpreted as oxide and phosphatic pseudomorphs after microbial cells. From analyses of the undigested bones, we infer that they represent remains of actinopterygian fish, a therapsid and unrecognizable parts of amphibians and/or reptiles. Additionally, hair-like structures found in one coprolite specimen occur as diagenetically altered (oxide-replaced) structures and moulds (or partly as pseudomorphs) in a microcrystalline carbonate-fluoride-bearing calcium phosphate. This suggests that the latest Permian therapsids probably were equipped with hair-like integument or hairsuit. If true, this is by far the oldest evidence of this mammalian character in the stem group of mammals. □ Coprolites, food residues, hair-like structures, Late Permian, microbial structures. Piotr Bajdek [piotr.bajdek@gmail.com], Aleja Naj swie z tszej Maryi Panny 20/20A 42-200 Cze z stochowa, Poland; Martin Qvarnstr€ om [martin.qvarnstrom@ebc.uu.se], Grzegorz Nied zwiedzki [grzegorz.niedzwiedzki@ebc.uu.se],

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Recurrent functional divergence of early tetrapod keratins in amphibian toe pads and mammalian hair

Cited by 13 publications

References 18 publications

Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals

Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals

Differential Evolution of the Epidermal Keratin Cytoskeleton in Terrestrial and Aquatic Mammals

Microbiota and food residues including possible evidence of pre-mammalian hair in Upper Permian coprolites from Russia

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