Expansion of the HSFY gene family in pig lineages : HSFY expansion in suids.

Benjamin M Skinner,Peter Ellis,Chris Tyler-Smith,Toby Hunt,Carole A Sargent,Fengtang Yang,Sandra Louzada,Kim Lachani,Beiyuan Fu,Nabeel A Affara,Carol Churcher

doi:10.1186/s12864-015-1650-x

Benjamin M Skinner, Peter Ellis + Show 9 more

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https://doi.org/10.1186/s12864-015-1650-x

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Abstract

BackgroundAmplified gene families on sex chromosomes can harbour genes with important biological functions, especially relating to fertility. The Y-linked heat shock transcription factor (HSFY) family has become amplified on the Y chromosome of the domestic pig (Sus scrofa), in an apparently independent event to an HSFY expansion on the Y chromosome of cattle (Bos taurus). Although the biological functions of HSFY genes are poorly understood, they appear to be involved in gametogenesis in a number of mammalian species, and, in cattle, HSFY gene copy number may correlate with levels of fertility.ResultsWe have investigated the HSFY family in domestic pig, and other suid species including warthog, bushpig, babirusa and peccaries. The domestic pig contains at least two amplified variants of HSFY, distinguished predominantly by presence or absence of a SINE within the intron. Both these variants are expressed in testis, and both are present in approximately 50 copies each in a single cluster on the short arm of the Y. The longer form has multiple nonsense mutations rendering it likely non-functional, but many of the shorter forms still have coding potential. Other suid species also have these two variants of HSFY, and estimates of copy number suggest the HSFY family may have amplified independently twice during suid evolution.ConclusionsThe HSFY genes have become amplified in multiple species lineages independently. HSFY is predominantly expressed in testis in domestic pig, a pattern conserved with cattle, in which HSFY may play a role in fertility. Further investigation of the potential associations of HSFY with fertility and testis development may be of agricultural interest.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1650-x) contains supplementary material, which is available to authorized users.

Highlights

Amplified gene families on sex chromosomes can harbour genes with important biological functions, especially relating to fertility
During our collaborative project sequencing the pig X and Y chromosomes, we became interested in a sequence that appeared repeatedly in the data being produced: the pig Y-linked heat shock transcription factor, HSFY
Both forms are expressed in testis, though only one is likely to produce a functional product. We find both variants in other suid species, with differing copy numbers suggesting independent amplifications during suid diversification

Summary

Introduction

Amplified gene families on sex chromosomes can harbour genes with important biological functions, especially relating to fertility. The Y-linked heat shock transcription factor (HSFY) family has become amplified on the Y chromosome of the domestic pig (Sus scrofa), in an apparently independent event to an HSFY expansion on the Y chromosome of cattle (Bos taurus). During our collaborative project sequencing the pig X and Y chromosomes (in submission; preprint in [1]), we became interested in a sequence that appeared repeatedly in the data being produced: the pig Y-linked heat shock transcription factor, HSFY. The gene encodes a heat shock transcription factor, but it appears not to function as such in humans; the DNA binding region does not bind DNA, and no promoters have been identified that HSFY targets [5, 6]. Earlier reports have suggested alterations to HSFY expression are associated with maturation arrest of spermatogenic cells [7]

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