Polymorphism in the 5'-flanking region of porcine heat shock protein 70.2 gene

Promoter variants at AP2 box region of Hsp70.1 affect thermal stress response and milk production traits in Frieswal cross bred cattle

Heat shock proteins (Hsp) are known to play major role in protection of cells from thermal stress. Nucleotide polymorphisms within the promoter of Hsp affect degree of expression and inducibility of Hsp mRNA. The present study aimed to investigate the effect of polymorphism within promoter region on the cellular expression of Hsp70.1 mRNA and association of identified polymorphisms with the physiological parameters during summer stress and milk production traits in dairy cattle. Two hundred Frieswal cows were genotyped using double PCR-RFLP to identify deletion of cytosine within the Hsp70.1 promoter AP2 box at base position 895. Homozygous wild type genotypes (CC) were found in lower frequency (39.29, n=78) than heterozygous cytosine deletion mutant genotypes (C-) (60.71, n=122). In the observed physiological parameters (rectal temperature, respiration rate and heat tolerance coefficient), cows that were homozygous wild types had better significant (P<0.05) summer tolerance than the heterozygous deletion genotypes. Cytosine deletion mutation in the promoter region negatively affected (P<0.01) the expression of Hsp70.1 mRNA in peripheral bovine mononuclear cells (PBMC) subjected to in vitro heat stress. Further association of observed polymorphism with the milk production traits was significant as the heterozygous cytosine deletion cows had lower total milk yield, peak yield, yield at 300 days, protein% (P<0.01) and fat% (P<0.05) than the native wild type promoter cows. The results from the present study suggest that the promoter region of bovine hsp70.1 gene is polymorphic and may be useful in selection of dairy cows for relatively better thermotolerance and higher milk production.

A 3'-UTR variant of the inducible porcine hsp70.2 gene affects mRNA stability

Large individual differences were observed in the abundance of transcripts from the hsp70.2 gene in primary fibroblast cultures sampled from 15 different pigs. While previously described functional promoter variants of this gene can partly account for the high variability of heat-induced increased abundance of transcripts, they are unrelated to the observed highly variable absolute amounts of hsp70.2 transcripts. Comparative sequence analysis revealed an alteration of the 3'-untranslated region (3'-UTR) sequences in these samples. The variant 3'-UTR allele proved to increase the half life of the hsp70.2 mRNA in reporter gene assays. It is suggested that the cellular stress response is significantly affected by the action and interaction of both promoter and 3'-UTR variants of the hsp70.2 gene.

Effects of single nucleotide polymorphisms in the 5'-flanking region of heat shock protein 70.2 gene on semen quality in boars

This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5'-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5'-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5'-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season.

Functional promoter variants of highly conserved inducible hsp70 genes significantly affect stress response

Promoter variants differing in potential cis-acting elements and showing impaired binding of corresponding transcription factors are described in the inducible porcine hsp70.2 gene (GC box; initiator-like region, InR) and in its bovine homologue (AP2 site), respectively. Interestingly, all these promoter variants are stable established in the analysed populations in spite of significant negative effects on transcriptional activity and indications of not neutral behaviour in response to breeding selection. Moreover, in pigs they are likely to be evolutionary fixed as suggested by their presence in recent breeds and in wild boars as well. Compensation of the effect of the observed 'down'-mutations by further yet unknown gene variants is assumed.