Activation of relaxin-related receptors by short, linear peptides derived from a collagen-containing precursor.
In a screening effort based on algorithmic predictions for novel G-protein-coupled receptor (GPCR) peptide activators, we were able to identify and examine two novel peptides (P59 and P74) which are short, linear, and derived from a natural, previously unidentified precursor protein containing a collagen-like repeat. Both peptides seemed to show an apparent cAMP-related effect on CHO-K1 cells transiently transfected with either LGR7 or LGR8, usually after treatment with cAMP-generating forskolin, compared to the same cells treated with forskolin plus relaxin. This activation was not found for the relaxin-3 receptor (GPR135). In a set of follow-up experiments, both peptides were found to stimulate cAMP production, mostly upon initial stimulation of cAMP production by 5 micro M forskolin in cells transfected with either LGR7 or LGR8. In a dye-free cell impedance GPCR activation assay, we were able to show that these peptides were also able to activate a cellular response mediated by these receptors. Although untransfected CHO-K1 cells showed some cellular activation by both relaxin and at least one of our newly discovered peptides, both LGR7- and LGR8-transfected cells showed a stronger response, indicating stimulation of a cellular pathway through activation of these receptors. In conclusion, we were able to show that these newly discovered peptides, which have no similarity to any member of the relaxin-insulin-like peptide family, are potential ligands for the relaxin-related family of receptors and as such might serve as novel candidates for relaxin-related therapeutic indications. Both peptides are linear and were found to be active after being chemically synthesized.
Shemesh
Ronen
R
Compugen Ltd., Tel-Aviv, Israel. ronens@compugen.co.il
Hermesh
Chen
C
Toporik
Amir
A
Levine
Zurit
Z
Novik
Amit
A
Wool
Assaf
A
Kliger
Yossef
Y
Rosenberg
Avi
A
Bathgate
Ross A D
RA
Cohen
Yossi
Y
D000818:Animals; D016466:CHO Cells; D005576:Colforsin / Q000494:pharmacology; D003094:Collagen / Q000737:chemistry*; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D008962:Models, Theoretical; D010455:Peptides / Q000494:pharmacology*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism*; D012065:Relaxin / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014162:Transfection
D010455:Peptides; C417543:RXFP1 protein, human; C472867:RXFP2 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D005576:Colforsin; D012065:Relaxin; D003094:Collagen; D000242:Cyclic AMP