Premium
Differences between lutropin‐mediated and choriogonadotropin‐mediated receptor activation
Author(s) -
Grzesik Paul,
Teichmann Anke,
Furkert Jens,
Rutz Claudia,
Wiesner Burkhard,
Kleinau Gunnar,
Schülein Ralf,
Gromoll Jörg,
Krause Gerd
Publication year - 2014
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.12718
Subject(s) - chemistry , microbiology and biotechnology , biology
The human lutropin/choriogonadotropin receptor ( hLHR ) for the gonadotropic hormones human luteinizing hormone ( hLH ; lutropin) and human choriogonadotropin ( hCG ) is crucial for normal sexual development and fertility. We aimed to unravel differences between the two hLHR hormones in molecular activation mechanisms at hLHR . We utilized a specific hLHR variant that lacks exon 10 ( hLHR ‐delExon10), which maintains full cAMP signaling by hCG , but decreases hLH ‐induced receptor signaling, resulting in a pathogenic phenotype. Exon 10 encodes 27 amino acids within the hinge region, which is an extracellular segment that is important for signaling and hormone interaction. Initially, we assumed that the lack of exon 10 might disturb intermolecular trans ‐activation of hLH , a mechanism that has been reported for hCG at hLHR . Coexpression of signaling‐deficient hLHR and binding‐deficient hLHR can be used to examine the mechanisms of receptor signaling, in particular intermolecular cooperation and intramolecular cis ‐activation. Therefore, hLHR ‐delExon10 was combined with the hLHR Lys605→Glu mutant, in which signaling is abolished, and the hLHR mutant Cys131→Arg, in which binding is deficient. We found that hCG signaling was partially rescued, indicating trans ‐activation. However, the hLH signal could not be restored via forced trans ‐activation with any construct. Fluorescence cross‐correlation spectroscopy detected oligomerization in all combinations, indicating that these functional differences cannot be explained by monomerization of hLHR ‐delExon10. Thus, our data demonstrate not only that the different behavior of hLH at hLHR ‐delExon10 is unlikely to be related to modified intermolecular receptor activation, but also that hLH may exclusively stimulate the targeted hLHR by cis ‐activation, whereas hCG is also capable of inducing trans ‐activation. Structured digital abstracthLHR and hLHR colocalize by confocal microscopy ( View interaction ) hLHR and hLHR physically interact by fluorescence correlation spectroscopy ( View interaction )