Background of Relaxin Receptors
The relaxin family peptide (RXFP) receptors are a family of G protein-coupled receptors, that mediate the hormonal and neuropeptide actions on their endogenous ligands relaxin family peptides and insulin-like peptides (INSL). Relaxin is characterized by vasodilatory, anti-fibrotic, angiogenic, anti-apoptotic, and anti-inflammatory properties, which has therapeutic effects on organ damage prevention, cardiovascular diseases, renal disease, and asthma. Chronic RXFP1 targeting therapies are under development.
Fig.1 Structural features of the relaxin family peptide receptor RXFP1. (Bathgate, 2013)
Distributions and Functions of Relaxin Receptors
The RXFP receptors are involved in the regulation of the cardiovascular system, formation of connective tissue and bone, reproduction, stress responses, anxiety and mood, arousal, spatial and social memory, and motivation. They are broadly distributed in the brain, reproductive tissues in both males and females, including semen, testis, ovary, pubic symphysis, cervix, uterus, and mammary glands, as well as in the heart, kidney, lung, thyroid, and colon.
Subtypes and Mechanisms of Relaxin Receptors
The family of RXFP receptors has 4 subtypes of G protein-coupled receptors, including RXFP1, RXFP2, RXFP3, and RXFP4 receptors. They promote signal transduction through Gs and Gi/Go proteins.
Receptor
|
Gene
|
Mechanism
|
Agonists
|
Antagonists
|
RXFP1 receptor
|
RXFP1
|
-
RXFP1 receptor couples with Gs protein to stimulate adenylyl cyclase
-
RXFP1 receptor couples with Gi/Go protein to inhibit adenylyl cyclase
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RXFP1 receptor couples to Gi3, activating AC5 through Gβγ-PI3K-PKCζ pathway
|
-
[33P]relaxin
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europium-labelled relaxin
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INSL-3
-
TamRLX
-
coumpound54
|
|
RXFP2 receptor
|
RXFP2
|
-
RXFP2 receptor couples with Gs protein to stimulate adenylyl cyclase
-
RXFP2 receptor couples with Gi/Go protein to inhibit adenylyl cyclase
|
-
[33P]relaxin
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[125I]INSL3
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NanoLuc-INSL3
-
relaxin
-
relaxin-1
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relaxin-3
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TamRLX
|
-
A(9-26)INSL3
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A(10-24)INSL3
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A(C10/15S)INSL3
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INSL3 B chain dimer analogue 8
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A(Δ10/15C)INSL3
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cyclic INSL3 B-chain analogue 6
|
RXFP3 receptor
|
RXFP3
|
-
RXFP3 receptor couples with Gi/Go protein to inhibit adenylyl cyclase
-
RXFP3 receptor activation leads to GTPγS binding as well as ERK1/2 and p38MAP kinase phosphorylation
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RXFP3 receptor couples to Gi2 in CHO cells, while in HEK293 cells couples to Gi3, GOB, or GOA proteins
|
-
[125I]relaxin-3
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[125I]relaxin-3-B/INSL5 A chimera
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R3/I5- SmBiT
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DOTA/Eu relaxin-3
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B1-27
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H3 14s18 stapled B-chain
|
-
europium-labelled R3(B1-22R)
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minimised relaxin-3 analogue 3
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R3 B1-22R
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R3(BΔ23-27)R/I5 chimeric peptide
|
RXFP4 receptor
|
RXFP4
|
-
RXFP4 receptor couples with Gi/Go protein to inhibit adenylyl cyclase
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RXFP4 receptor activation leads to ERK1/2, p38MAPK, Akt Ser473 and Thr308, and S6RP phosphorylation
|
-
[125I]relaxin-3
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[125I]relaxin-3-B/INSL5 A chimera
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R3/15
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ΔR3/I5
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compound 7a
|
-
R3(BΔ23-27)R/I5 chimeric peptide
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INSL5-A13NR
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minimised relaxin-3 analogue 3
|
RXFP1 RXFP2 RXFP3 RXFP4
Assay No.
|
Assay Name
|
Host Cell
|
Assay Type
|
Datasheet
|
cAMP Assay
|
S01YF-0922-KX1205
|
Magic™ Human RXFP1 In Vitro Agonist & Antagonist cAMP Assay
|
HEK293
|
cAMP Assay
|
|
S01YF-0922-KX1206
|
Magic™ Human RXFP1 In Vitro Agonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1207
|
Magic™ Human RXFP1 In Vitro Antagonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1208
|
Magic™ Human RXFP1 In Vitro PAM cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1209
|
Magic™ Mouse RXFP1 In Vitro Agonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1210
|
Magic™ Mouse RXFP1 In Vitro Antagonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-1122-KX856
|
Magic™ Rabbit RXFP1 In Vitro cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-1122-KX857
|
Magic™ Rat RXFP1 In Vitro cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-1122-KX853
|
Magic™ Dog RXFP1 In Vitro cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
Assay No.
|
Assay Name
|
Host Cell
|
Assay Type
|
Datasheet
|
cAMP Assay
|
S01YF-0922-KX1212
|
Magic™ Human RXFP2 In Vitro Agonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1213
|
Magic™ Human RXFP2 In Vitro Antagonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1214
|
Magic™ Human RXFP2 In Vitro PAM cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
Assay No.
|
Assay Name
|
Host Cell
|
Assay Type
|
Datasheet
|
cAMP Assay
|
S01YF-0922-KX1216
|
Magic™ Human RXFP3 In Vitro Agonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1219
|
Magic™ Human RXFP3 In Vitro Antagonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1222
|
Magic™ Human RXFP3 In Vitro PAM cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
Calcium Flux Assay
|
S01YF-1122-KX858
|
Magic™ Human RXFP3 In Vitro Calcium Flux Assay
|
CHO-K1
|
Calcium Flux Assay
|
|
β-Arrestin Assay
|
S01YF-0922-KX1215
|
Magic™ Human RXFP3 In Vitro Agonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1218
|
Magic™ Human RXFP3 In Vitro Antagonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1221
|
Magic™ Human RXFP3 In Vitro PAM β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1224
|
Magic™ Mouse RXFP3 In Vitro Agonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1225
|
Magic™ Mouse RXFP3 In Vitro Antagonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1226
|
Magic™ Mouse RXFP3 In Vitro PAM β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
Internalization Assay
|
S01YF-0922-KX1217
|
Magic™ Human RXFP3 In Vitro Agonist Internalization Assay
|
U2OS
|
Internalization Assay
|
|
S01YF-0922-KX1220
|
Magic™ Human RXFP3 In Vitro Antagonist Internalization Assay
|
U2OS
|
Internalization Assay
|
|
S01YF-0922-KX1223
|
Magic™ Human RXFP3 In Vitro PAM Internalization Assay
|
U2OS
|
Internalization Assay
|
|
[35S]GTPγS Binding Assay
|
S01YF-1122-KX860
|
Magic™ Human RXFP3 In Vitro [35S]GTPγS binding Assay
|
CHO-K1
|
[35S]GTPγS binding Assay
|
|
Assay No.
|
Assay Name
|
Host Cell
|
Assay Type
|
Datasheet
|
cAMP Assay
|
S01YF-0922-KX1228
|
Magic™ Human RXFP4 In Vitro Agonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1230
|
Magic™ Human RXFP4 In Vitro Antagonist cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
S01YF-0922-KX1232
|
Magic™ Human RXFP4 In Vitro PAM cAMP Assay
|
CHO-K1
|
cAMP Assay
|
|
Calcium Flux Assay
|
S01YF-1122-KX861
|
Magic™ Human RXFP4 In Vitro Calcium Flux Assay
|
CHO-K1
|
Calcium Flux Assay
|
|
β-Arrestin Assay
|
S01YF-0922-KX1227
|
Magic™ Human RXFP4 In Vitro Agonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1229
|
Magic™ Human RXFP4 In Vitro Antagonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1231
|
Magic™ Human RXFP4 In Vitro PAM β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1233
|
Magic™ Mouse RXFP4 In Vitro Agonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1234
|
Magic™ Mouse RXFP4 In Vitro Antagonist β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
S01YF-0922-KX1235
|
Magic™ Mouse RXFP4 In Vitro PAM β-Arrestin Assay
|
CHO-K1
|
β-Arrestin Assay
|
|
[35S]GTPγS Binding Assay
|
S01YF-1122-KX863
|
Magic™ Human RXFP4 In Vitro [35S]GTPγS binding Assay
|
CHO-K1
|
[35S]GTPγS binding Assay
|
|
S01YF-1122-KX864
|
Magic™ Mouse RXFP4 In Vitro [35S]GTPγS binding Assay
|
CHO-K1
|
[35S]GTPγS binding Assay
|
|
Published Data
Paper Title
|
Identification of small-molecule agonists of human relaxin family receptor 1 (RXFP1) by using a homogenous cell-based cAMP assay
|
Journal
|
Journal of biomolecular screening
|
Published
|
2013
|
Abstract
|
Relaxin is a hormone involved in multiple biological functions, such as female reproduction and parturition and regulation of cardiovascular, renal, pulmonary, and hepatic functions. It plays a role in regulating extracellular matrix remodeling, cell invasiveness, proliferation, differentiation, and overall tissue homeostasis. RXFP1 is a cognate relaxin GPCR signaling via cyclic AMP second messenger. The study aimed to develop small-molecule agonists for the RXFP1 receptor. They developed a quantitative high-throughput platform for RXFP1 agonist screening based on homogenous cell-based HTRF cyclic AMP (cAMP) assay technology. They screened two small-molecule agonists with similar structures out of more than 365 677 compounds. They also used a counterscreen with HEK293T cells transfected with an unrelated GPCR vasopressin 1b receptor.
|
Result
|
The EC50 values were 203 pM and 494 pM for relaxin and 164 nM and 193 nM for forskolin in 384-well and 1536-well formats, respectively. They screened two small-molecule agonists with similar structures out of more than 365 677 compounds using homogenous cell-based HTRF cyclic AMP (cAMP) assay technology with human embryonic kidney cells stably transfected with human RXFP1 receptor (HEK293-RXFP1). The results of counterscreen with HEK293T cells transfected with an unrelated GPCR vasopressin 1b receptor showed no compound activity. It has been also demonstrated that these small-molecule agonists showed selectivity against the RXFP2 receptor. In summary, this study provided a basis for future medicinal chemistry optimization of selective relaxin receptor agonists.
Fig.2 Concentration response of human RXFP1 agonists. (Chen, 2013)
|
References
-
Bathgate, R. A. D.; et al. Relaxin family peptides and their receptors. Physiological reviews. 2013, 93(1): 405-480.
-
Chen, C. Z.; et al. Identification of small-molecule agonists of human relaxin family receptor 1 (RXFP1) by using a homogenous cell-based cAMP assay. Journal of biomolecular screening. 2013, 18(6): 670-677.
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