Sironen A, Fischer D, Laiho A, Gyenesei A, Vilkki J
Agrifood Research Finland, MTT, Biotechnology and Food Research, Genomics, FI-36100, Jokioinen, Finland.
Anim Genet. 2014 Aug;45(4):500-7. doi: 10.1111/age.12153. Epub 2014 Apr 9.
The immotile short tail sperm (ISTS) defect was recognized in the Finnish Yorkshire population at the end of the 1990s when several affected boars were identified. The causal mutation for this defect is a recent L1 insertion within the SPEF2 gene. In 2001, the insertion frequency was already 0.23. Even though all homozygous boars are eliminated from the population due to infertility, the amount of affected boars increased rapidly until marker-assisted selection against the defect was established. Previously we identified an association between the L1 insertion and litter size in the first parity. In this study, we analyzed the expression of the genomic region adjacent to the L1 insertion on porcine chromosome 16. Based on the RNA-seq data analysis, prolactin receptor (PRLR) was identified as down-regulated in the oviduct of ISTS homozygous sows. Quantitative PCR (qPCR) analysis confirmed the significant down-regulation of PRLR in the ovary, oviduct, and uterus of ISTS homozygous and carrier sows compared with controls. In addition, three unannotated loci between PRLR and SPEF2 showed some transcription activity in the analyzed samples. We further investigated the possible mechanisms of the L1 influence on the decrease in the identified gene expression. The methylation pattern of the PRLR gene region appeared unaffected. However, reads mapping to the L1 sequence indicated an increase in L1 antisense promoter expression in the ISTS homozygous animals. The current data suggest that the presence of the L1 affects by some mechanism the expression patterns upstream of the insertion site.
20世纪90年代末，在芬兰约克郡猪群中发现了不动短尾精子（ISTS）缺陷，当时鉴定出了几头受影响的公猪。这种缺陷的致病突变是SPEF2基因内最近发生的L1插入。2001年，插入频率已达0.23。尽管所有纯合公猪因不育而被从猪群中淘汰，但受影响的公猪数量仍迅速增加，直到建立了针对该缺陷的标记辅助选择方法。此前我们发现L1插入与头胎产仔数之间存在关联。在本研究中，我们分析了猪16号染色体上与L1插入相邻的基因组区域的表达情况。基于RNA测序数据分析，在ISTS纯合母猪的输卵管中，催乳素受体（PRLR）被确定为表达下调。定量PCR（qPCR）分析证实，与对照组相比，ISTS纯合母猪和携带者母猪的卵巢、输卵管和子宫中PRLR均显著下调。此外，在PRLR和SPEF2之间的三个未注释位点在分析样本中显示出一些转录活性。我们进一步研究了L1影响所鉴定基因表达下降的可能机制。PRLR基因区域的甲基化模式似乎未受影响。然而，映射到L1序列的读数表明，ISTS纯合动物中L1反义启动子的表达增加。目前的数据表明，L1的存在通过某种机制影响插入位点上游的表达模式。
