Axis 3 | Post-testicular sperm maturation

Nearly 15% of couples consult for infertility and in France more than 3% of children are born through the use of medically assisted procreation. In half of the cases, infertility is of male origin. Spermatogenesis is a highly controlled process based on the coordinated expression of a set of genes and proteins. Its purpose is the production of a functional gamete, the sperm, which is neither fertile nor mobile when released. During the transit of sperm through the epididymis, most of its surface proteins will undergo many post-translational modifications.

These maturation steps are not controlled exclusively by the gamete genome, but also rely on a set of spatial events, including the activity of epithelial cells in different areas of the epididymis and the presence of surrounding proteins in seminal plasma. To date, there are strong clinical data that establish a link between sperm quality and post-testicular maturation of the gamete. However, it is necessary to better understand the molecular basis underlying the stages of this maturation.

Our objective is to identify in each region of the epididymis, specific mechanisms of gamete maturation whose alteration may be linked to the fertilizing capacity of spermatozoa and therefore to certain male infertilities, in particular idiopathic. We attempt to answer the following questions:

  • What are the main post-translational modifications altering the surface proteins of spermatozoa during the transit of gametes in the epididymis?
  • What are the exchanges and transformation of existing proteins between the epididymis, seminal plasma and sperm?
  • Is it possible to correlate these events with specific regions of the epididymis and map their dynamics in situ?
  • Can we correlate defects in the maturation of one or more proteins with the quality of the gamete?

Relevant publications : PubMed