Molecular cloning and functional characterisation of the human fertilin β(FTN-β) and SPAM1 promoters

Abstract

Among the molecules that play an essential role in the early steps of the process of fertilisation, and in the interaction of the sperm with the egg, are the sperm adhesion molecule 1 (SPAM1) and fertilin
β(FTN-β). This interaction, mediated by various molecules on the gametes, starts with sperm-egg adhesion and ultimately results in the fusion of the membranes. The human fertilin β(FTN-β) and SPAM1
promoters were cloned and characterised to determine their similarity with other testis germ cellsspecific promoters, and to assess their functionality and tissue specificity. Various fragments of the
promoters were fused with GFP in an expression cassette for an in situ transcription assay using four different cell types. Transcription initiation sites (TSS) were mapped by RACE at -127 nucleotide
position relative to the initiation codon (ATG) in SPAM1 and at -64 nucleotide position in FTN-b. Neither the SPAM1 nor FTN-b promoter have consensus TATA or CCAAT boxes; however, they have the
initiator (Inr) motif at the transcription initiation sites and the TSF (Testis Specific Factor) motif pair, one in either orientation. In addition FTN-b has a DPE (downstream promoter element) at +30 position
relative to the transcription start site, while SPAM1 has CRE (Cyclic-AMP Response Element) motifs at positions -28 and -70.