An intronic insertion in KPL2 results in aberrant splicing and causes the immotile short-tail sperm defect in the pig

doi:10.1073/pnas.0506318103

An intronic insertion in KPL2 results in aberrant splicing and causes the immotile short-tail sperm defect in the pig

*MTT Agrifood Research Finland, Animal Production Research, Animal Breeding, FIN-31600, Jokioinen, Finland;
^‡Department of Genetics and Biotechnology, Danish Institute of Agricultural Sciences, P.O. Box 50, DK-8830 Tjele, Denmark;
^§Department of Clinical Veterinary Sciences, Saari Unit, Faculty of Veterinary Medicine, University of Helsinki, FIN-04920, Saarentaus, Finland; and
^¶MTT Agrifood Research Finland, Food Research, FIN-31600, Jokioinen, Finland

Edited by Ryuzo Yanagimachi, University of Hawaii, Honolulu, HI, and approved February 3, 2006 (received for review July 25, 2005)

Abstract

The immotile short-tail sperm defect is an autosomal recessive disease within the Finnish Yorkshire pig population. This disease specifically affects the axoneme structure of sperm flagella, whereas cilia in other tissues appear unaffected. Recently, the disease locus was mapped to a 3-cM region on porcine chromosome 16. To facilitate identification of candidate genes, we constructed a porcine-human comparative map, which anchored the disease locus to a region on human chromosome 5p13.2 containing eight annotated genes. Sequence analysis of a candidate gene KPL2 revealed the presence of an inserted retrotransposon within an intron. The insertion affects splicing of the KPL2 transcript in two ways; it either causes skipping of the upstream exon, or causes the inclusion of an intronic sequence as well as part of the insertion in the transcript. Both changes alter the reading frame leading to premature termination of translation. Further work revealed that the aberrantly spliced exon is expressed predominantly in testicular tissue, which explains the tissue-specificity of the immotile short-tail sperm defect. These findings show that the KPL2 gene is important for correct axoneme development and provide insight into abnormal sperm development and infertility disorders.

Footnotes

^†To whom correspondence should be addressed. E-mail: anu.sironen{at}mtt.fi
Author contributions: A.S., B.T., and J.V. designed research; A.S., M.A., and B.T. performed research; B.T. contributed new reagents/analytic tools; A.S. and V.A. analyzed data; and A.S. and B.T. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. DQ119847 for the Sus scrofa KPL2 mRNA sequence and DQ092447 for the Sus scrofa KPL2 partial genomic sequence).
Abbreviations:

PCD,

primary ciliary dyskinesia;

ISTS,

immotile short-tail sperm;

qPCR,

quantitative PCR.