Search Results
You are looking at 1 - 2 of 2 items for
- Author: H Marichatou x
- Refine by access: All content x
Search for other papers by M Chopineau in
Google Scholar
PubMed
Search for other papers by N Martinat in
Google Scholar
PubMed
Search for other papers by C Troispoux in
Google Scholar
PubMed
Search for other papers by H Marichatou in
Google Scholar
PubMed
Search for other papers by Y Combarnous in
Google Scholar
PubMed
Search for other papers by F Stewart in
Google Scholar
PubMed
Search for other papers by F Guillou in
Google Scholar
PubMed
Horse (Equus caballus) luteinizing hormone (eLH) and chorionic gonadotrophin (eCG), which have the same amino acid sequence, are unusual in that, although they express only LH activity in equids, they express dual LH and FSH activities in all other species tested. Donkey (Equus asinus) LH (dkLH) and CG (dkCG), which also share an identical peptide backbone, have been less well characterized and conflicting results concerning their FSH activity in heterologous species have appeared in the literature. In order to assess and compare the intrinsic LH and FSH activities of the horse and donkey LHs in heterologous species, recombinant eLH (r.eLH/CG) and recombinant dkLH (r.dkLH/CG) were expressed, for the first time, in COS-7 cells. Their LH activities were assessed in a rat Leydig cell bioassay, and their FSH activities were estimated in a bioassay using Y1 cells stably expressing the human FSH receptor. Human CG (hCG) was expressed (r.hCG) and analysed in the same system. The results showed that, whereas r.dkLH/CG was about twice as active as r.eLH/CG in the LH bioassay, it was five times less active than r.eLH/CG in the FSH bioassay; r.hCG was about three times less active than r.eLH/CG in the LH bioassay but was completely inactive in the FSH bioassay. These results confirm that dkLH/CG possesses significant FSH activity in heterologous species that is not attributable to contamination with FSH.
Journal of Endocrinology (1997) 152, 371–377
Search for other papers by M Chopineau in
Google Scholar
PubMed
Search for other papers by N Martinat in
Google Scholar
PubMed
Search for other papers by H Marichatou in
Google Scholar
PubMed
Search for other papers by C Troispoux in
Google Scholar
PubMed
Search for other papers by C Auge-Gouillou in
Google Scholar
PubMed
Search for other papers by F Stewart in
Google Scholar
PubMed
Search for other papers by Y Combarnous in
Google Scholar
PubMed
Search for other papers by F Guillou in
Google Scholar
PubMed
Horse LH/chorionic gonadotrophin (eLH/CG) exhibits, in addition to its normal LH activity, a high FSH activity in all other species tested. Donkey LH/CG (dkLH/CG) also exhibits FSH activity in other species, but about ten times less than the horse hormone. In order to understand the molecular basis of these dual gonadotrophic activities of eLH/CG and dkLH/CG better, we expressed, in COS-7 cells, hybrids between horse and donkey subunits, between horse or donkey alpha-subunit and human CG beta (hCG beta), and also between the porcine alpha-subunit and horse or donkey LH/CG beta. The resultant recombinant hybrid hormones were measured using specific FSH and LH in vitro bioassays which give an accurate measure of receptor binding specificity and activation. Results showed that it is the beta-subunit that determines the level of FSH activity, in agreement with the belief that it is the beta-subunit which determines the specificity of action of the gonadotrophins. However, donkey LH/CG beta combined with a porcine alpha-subunit exhibited no FSH activity although it showed full LH activity. Moreover, the hybrid between horse or donkey alpha-subunit and hCG beta also exhibited only LH activity. Thus, the low FSH activity of dkLH/CG requires an equine (donkey or horse) alpha-subunit combined with dkLH/CG beta. These results provide the first evidence that an alpha-subunit can influence the specificity of action of a gonadotrophic hormone.
