Mammalian keratin associated proteins (KRTAPs) subgenomes: disentangling hair diversity and adaptation to terrestrial and aquatic environments

BMC Genomics

Agostinho Antunes³  Warren E Johnson¹  Stephen J O’Brien²  Vítor Vasconcelos³  Emanuel Maldonado⁴  Imran Khan³ 

[1] Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Rd, Front Royal, VA 22630, USA;Oceanographic Center 8000 N. Ocean Drive, Nova Southeastern University, Ft Lauderdale, Florida 33004, USA;Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal;CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas 177, 4050-123 Porto, Portugal

关键词: Positive selection;    Recombination;    Gene conversion;    Hair;    Keratin;    Keratin Associated Proteins;    Gene family;    Concerted evolution;   

Others  :  1140645
DOI  :  10.1186/1471-2164-15-779

 received in 2014-02-19, accepted in 2014-07-30,  发布年份 2014

【 摘 要 】

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.

【 授权许可】

   
2014 Khan et al.; licensee BioMed Central Ltd.

【 图 表 】

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