Regulators of sperm function

Matrix proteins (e.g. fibronectin, laminin and vitronectin) and their receptors, especially beta 1 integrins, may play a role in sperm-oocyte interactions. These proteins are well described on spermatogenic cells but especially in ejaculated spermatozoa, the presence of mRNA as a necessity for their synthesis is not clear. Therefore the mRNA synthesis of the beta 1, alpha 3, alpha 4, alpha 5 and alpha 6 chains (fibronectin and laminin receptors) of the beta 1 integrins was investigated by nested reverse transcription-polymerase chain reaction (RT-PCR) in spermatozoa of human semen samples (n = 18) which showed normal classical semen parameters after swim-up preparation. After the second amplification, we obtained specific signals for mRNA transcripts of the beta 1, alpha 3, alpha 4 and alpha 6 chains in 17 of 18 semen samples investigated. All control PCRs were negative for somatic cell transcripts and contamination by somatic cells was excluded. These results demonstrate for the first time that human ejaculated spermatozoa contain the mRNA transcripts of beta 1 integrins and support the role of these proteins in adhesive mechanisms in the fertilization process.