Transcription of the human and rodent <it>SPAM1 / PH-20 </it>genes initiates within an ancient endogenous retrovirus

• Main Authors: Dunn Catherine A, Mager Dixie L
• Format: Article
• Language: English
• Published: BMC 2005-04-01
• Series: BMC Genomics
• Online Access: http://www.biomedcentral.com/1471-2164/6/47
• ISSN: 1471-2164

<p>Abstract</p> <p>Background</p> <p>Sperm adhesion molecule 1 (SPAM1) is the major mammalian testicular hyaluronidase and is expressed at high levels in sperm cells. SPAM1 protein is important for penetration of the cumulus cell layer surrounding the ovum, and is also involved in zona pellucida binding and sperm intracellular signalling. A previous study had identified <it>SPAM1 </it>as one of the many human genes that initiate within a transposable element.</p> <p>Results</p> <p>Examination of the human, mouse and rat <it>SPAM1 </it>loci revealed that transcripts initiate within the <it>pol </it>gene of an endogenous retrovirus (ERV) element. This is highly unusual, as all previously identified ERV-initiated cellular gene transcripts initiate within the viral long terminal repeat promoter. The <it>SPAM1 </it>locus therefore represents an example of the evolution of a promoter from protein-coding sequence. We have identified novel alternative promoter and splicing variants of human and murine <it>SPAM1</it>. We show that all transcript variants are expressed primarily in the testis and are predicted to encode identical proteins.</p> <p>Conclusion</p> <p>The testis-specific promoters of the human and mouse <it>SPAM1 </it>genes are derived from sequence that was originally part of an ERV <it>pol </it>gene. This represents the first known example of an ERV-derived promoter acting in a gender-specific manner.</p>