Gene loss in keratinization programs accompanies adaptation of cetacean skin to aquatic lifestyle

Oh, Ji Won; Chung, Oksung; Cho, Yun Sung; MacGregor, Grant R.; Plikus, Maksim V.

doi:10.1111/exd.12756

Cited by 19 publications

(21 citation statements)

References 16 publications

(23 reference statements)

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“…However, the expression of FLG and LOR is confined to the epidermis with the exception of the keratinizing hard plate mucosa [20,110] ( Table 1), suggesting that these major KG proteins are instrumental in covering the dry, outer squamous epithelium. By analogy, recent phylogenetic evidence may give us a clue to understanding its significance; cetaceans such as whales or dolphins have lost the FLG gene to adapt their skin to aquatic lifestyles [1,111,112].…”

Section: Atopy: Imprinted Cutaneous Immunological Memory?mentioning

confidence: 99%

Loricrin: Past, Present, and Future

Ishitsuka

Roop

2020

IJMS

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The terminal differentiation of the epidermis is a complex physiological process. During the past few decades, medical genetics has shown that defects in the stratum corneum (SC) permeability barrier cause a myriad of pathological conditions, ranging from common dry skin to lethal ichthyoses. Contrarily, molecular phylogenetics has revealed that amniotes have acquired a specialized form of cytoprotection cornification that provides mechanical resilience to the SC. This superior biochemical property, along with desiccation tolerance, is attributable to the proper formation of the macromolecular protein-lipid complex termed cornified cell envelopes (CE). Cornification largely depends on the peculiar biochemical and biophysical properties of loricrin, which is a major CE component. Despite its quantitative significance, loricrin knockout (LKO) mice have revealed it to be dispensable for the SC permeability barrier. Nevertheless, LKO mice have brought us valuable lessons. It is also becoming evident that absent loricrin affects skin homeostasis more profoundly in many more aspects than previously expected. Through an extensive review of aggregate evidence, we discuss herein the functional significance of the thiol-rich protein loricrin from a biochemical, genetic, pathological, metabolic, or immunological aspect with some theoretical and speculative perspectives.

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Section: Atopy: Imprinted Cutaneous Immunological Memory?mentioning

confidence: 99%

Loricrin: Past, Present, and Future

Ishitsuka

Roop

2020

IJMS

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“…[11][12][13] Our recent studies have suggested that SFTPs originated prior to the diversification of amniotes (mammals, reptiles and birds). [14][15][16] However, the evolutionary origin of SFTPs has remained uncertain because of incomplete genome data of the next relatives of amniotes, the amphibians.…”

Section: Questions Addressedmentioning

confidence: 99%

Filaggrin has evolved from an “S100 fused‐type protein” (SFTP) gene present in a common ancestor of amphibians and mammals

Mlitz

Hussain

Tschachler

et al. 2017

Experimental Dermatology

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The expression of filaggrin in differentiated keratinocytes and the association of filaggrin mutations with ichthyosis vulgaris and atopic dermatitis suggest that this prototypical member of the S100 fusedtype protein (SFTP) family plays a key role in the epidermal barrier to the environment. Here, we report that SFTP genes are present not only in amniotes but also in amphibians. Four SFTPs are expressed in the skin of the frog Xenopus laevis. The results of this study indicate that filaggrin has evolved from an ancestral SFTP that may have contributed to skin modifications during the evolutionary transition to terrestrial life.

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“…We have reported that this apparent loss of the classical epidermal differentiation was associated with the loss or mutational inactivation of caspase‐14 and most filaggrin‐type proteins in cetaceans . Moreover, genes encoding late cornified envelope (LCE) proteins and many other keratinocyte late differentiation genes (our unpublished data) have been lost in cetaceans.…”

Section: Introductionmentioning

confidence: 82%

Phylogenetic profiling and gene expression studies implicate a primary role of PSORS1C2 in terminal differentiation of keratinocytes

Zadeh

Mlitz

Lachner

et al. 2017

Experimental Dermatology

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PSORS1C2 is a gene located between coiled-coil alpha-helical rod protein 1 (CCHCR1) and corneodesmosin (CDSN) within the psoriasis susceptibility locus 1 (PSORS1). Here, we performed a comparative genomics analysis of the as-yet incompletely characterized PSORS1C2 gene and determined its expression pattern in human tissues. In contrast to CCHCR1, which is common to all vertebrates investigated, PSORS1C2 and CDSN are present exclusively in mammals, indicating that the latter genes have originated after the evolutionary divergence of mammals and reptiles. CDSN is conserved in aquatic mammals, whereas PSORS1C2 orthologs contain gene-inactivating frame shift mutations in whales and dolphins, in which the epidermal differentiation programme has degenerated. Reverse-transcription PCR screening demonstrated that, in human tissues, PSORS1C2 is expressed principally in the epidermis and weakly in the thymus. PSORS1C2 mRNA was strongly upregulated during terminal differentiation of human keratinocytes in vitro. Immunohistochemistry revealed exclusive expression of PSORS1C2 in the granular layer of the epidermis and in cornifying epithelial cells of Hassall's corpuscles of the thymus. In summary, our results identify PSORS1C2 as a keratinocyte cornification-associated protein that has originated in evolutionarily basal mammals and has undergone gene inactivation in association with the loss of the skin barrier function in aquatic mammals.

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Gene loss in keratinization programs accompanies adaptation of cetacean skin to aquatic lifestyle

Cited by 19 publications

References 16 publications

Loricrin: Past, Present, and Future

Loricrin: Past, Present, and Future

Filaggrin has evolved from an “S100 fused‐type protein” (SFTP) gene present in a common ancestor of amphibians and mammals

Phylogenetic profiling and gene expression studies implicate a primary role of PSORS1C2 in terminal differentiation of keratinocytes

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