Mammalian Keratin Associated Proteins (KRTAPs) Subgenomes: Disentangling Hair Diversity and Adaptation to Terrestrial and Aquatic Environments

Authors

Imran Khan, Universidade do Porto - Portugal
Emanuel Maldonado, Universidade do Porto - Portugal
Vitor Vasconcelos, Universidade do Porto - Portugal
Stephen J. O'Brien, Nova Southeastern UniversityFollow
Warren E. Johnson, Smithsonian Institution
Agostinho Antunes, Universidade do Porto - Portugal

Document Type

Article

Publication Title

BMC Genomics

ISSN

1471-2164

Publication Date

2014

Keywords

Concerted evolution, Gene family, Keratin associated proteins, Keratin, Hair, Gene conversion, Recombination, Positive selection

Abstract

Background: Adaptation of mammals to terrestrial life was facilitated by the unique vertebrate trait of body hair, which occurs in a range of morphological patterns. Keratin associated proteins (KRTAPs), the major structural hair shaft proteins, are largely responsible for hair variation.

Results: We exhaustively characterized the KRTAP gene family in 22 mammalian genomes, confirming the existence of 30 KRTAP subfamilies evolving at different rates with varying degrees of diversification and homogenization. Within the two major classes of KRTAPs, the high cysteine (HS) subfamily experienced strong concerted evolution, high rates of gene conversion/recombination and high GC content. In contrast, high glycine-tyrosine (HGT) KRTAPs showed evidence of positive selection and low rates of gene conversion/recombination. Species with more hair and of higher complexity tended to have more KRATP genes (gene expansion). The sloth, with long and coarse hair, had the most KRTAP genes (175 with 141 being intact). By contrast, the "hairless" dolphin had 35 KRTAPs and the highest pseudogenization rate (74% relative to the 19% mammalian average). Unique hair-related phenotypes, such as scales (armadillo) and spines (hedgehog), were correlated with changes in KRTAPs. Gene expression variation probably also influences hair diversification patterns, for example human have an identical KRTAP repertoire as apes, but much less hair.

Conclusions: We hypothesize that differences in KRTAP gene repertoire and gene expression, together with distinct rates of gene conversion/recombination, pseudogenization and positive selection, are likely responsible for micro and macro-phenotypic hair diversification among mammals in response to adaptations to ecological pressures.

DOI

10.1186/1471-2164-15-779

Volume

15

Issue

779

First Page

1

Last Page

18

Comments

©2014 Khan et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Additional Comments

Portuguese Fundação para a Ciência e a Tecnologia grant #: SFRH/BD/48518/2008; Russian Ministry of Science Mega-grant #: 11.G34.31.0068

NSUWorks Citation

Imran Khan, Emanuel Maldonado, Vitor Vasconcelos, Stephen J. O'Brien, Warren E. Johnson, and Agostinho Antunes. 2014. Mammalian Keratin Associated Proteins (KRTAPs) Subgenomes: Disentangling Hair Diversity and Adaptation to Terrestrial and Aquatic Environments .BMC Genomics , (779) : 1 -18. https://nsuworks.nova.edu/occ_facarticles/346.