Structure et relations structure-activité des hormones folliculo-stimulantes recombinantes humaines.

Abstract

Les hormones glycoproteiques, dont font partie les gonadotrophines, sont les molecules les plus complexes possedant une activite hormonale. Elles sont constituees de deux sous-unites differentes, <alpha> et <beta>, liees de maniere non covalente et portant, chacune, une ou plusieurs chaines oligo-saccharidiques. L' activite biologique globale des gonadotrophines est dependante de leur efficacite lors de trois etapes successives: (1) leur maintien plus ou moins long dans la circulation; (2) leur affinite pour leur recepteur specifique; et (3) leur aptitude a stimuler les reponses de leurs cellules cibles apres liaison au recepteur. Les gonadotrophines recombinantes ne peuvent etre produites dans des bacteries mais seulement dans des cellules eucaryotes. La seule voie d' amelioration a court terme de la qualite des FSH recombinantes semble etre l' augmentation de leur demi-vie et la diminution de leur polymorphisme par l' obtention de chaines saccharidiques tri- ou tetra-antennees et leur sialylation la plus complete possible.

As a glycoprotein hormone, follicle-stimulating hormone (FSH) exhibits a highly complex structure with two different non-covalently associated subunits (the common alpha and the specific beta) both bearing two N-linked carbohydrate chains. Until now, recombinant human FSH with in vivo activity could be obtained only in mammalian host cells because other usual eukaryotic cell systems such as insect cells and yeasts do not synthesize the correct complex carbohydrates that are necessary for sufficiently long half-life in plasma. Many recent studies have dealt with the delineation of the regions of the molecule that are involved in the successive steps of the hormone action: half-life in blood and bio-availability, affinity and specificity of binding to the FSH receptor, efficiency of signal transduction after binding and target cell desensitization. The present paper deals with our current knowledge of the involvement of the peptide and carbohydrate portions of the alpha and beta subunits in these steps and future prospects in the development of better recombinant human FSHs or simpler molecules with FSH activity. [References: 31]