Recombinant Human Probable G-protein coupled receptor 160 (GPR160)

What is the basic structure and classification of GPR160?

GPR160 belongs to the class A G-protein coupled receptor (GPCR) subfamily. It was previously considered an orphan receptor until recent deorphanization identified cocaine- and amphetamine-regulated transcript peptide (CARTp) as its endogenous ligand . Like other GPCRs, it features the characteristic seven-transmembrane domain structure that facilitates signal transduction across the cell membrane. Research methodologies to investigate its structure typically include computational modeling, X-ray crystallography, and functional expression studies in cell systems.

What is the normal tissue distribution pattern of GPR160?

GPR160 shows tissue-specific expression patterns. In normal physiological conditions, GPR160 is expressed at low levels in dorsal root ganglion (DRG) neurons . Research has shown that in pathological conditions such as bone cancer pain (BCP), GPR160 expression increases significantly in small-diameter C-fiber type neurons, particularly those innervating the tibia . The proper methodology to investigate tissue distribution includes techniques such as RNAscope in situ hybridization, immunohistochemistry, and quantitative PCR to detect mRNA and protein expression levels across different tissues.

What signaling pathways are activated downstream of GPR160?

While specific downstream signaling pathways remain under investigation, research indicates that GPR160 activation leads to increased neuronal excitability in DRG neurons, as demonstrated by electrophysiological studies showing changes in action potential threshold and rheobase . Current methodological approaches include whole-cell patch-clamp recordings to assess neuronal excitability in GPR160-expressing cells. When designing experiments to study GPR160 signaling, researchers should include appropriate controls such as GPR160 knockout models or selective inhibitors to distinguish between GPR160-specific and non-specific effects.

How does GPR160 contribute to neuropathic pain mechanisms?

GPR160 plays a crucial role in neuropathic pain development. Research using Gpr160 knockout mice has demonstrated that these animals fail to develop behavioral hypersensitivities in models of neuropathic pain caused by constriction of the sciatic nerve . Methodologically, researchers investigating GPR160's role in neuropathic pain should employ behavioral testing paradigms such as mechanical allodynia and thermal hyperalgesia assessments. Additionally, administration of CARTp (the endogenous ligand for GPR160) via intrathecal or intraplantar injections induces pain behaviors that are dependent on GPR160 expression, as these effects are absent in Gpr160 knockout mice .

What role does GPR160 play in bone cancer pain (BCP)?

GPR160 is significantly upregulated in DRG neurons following tumor infiltration in bone cancer pain models. Research shows that Gpr160 mRNA and protein levels increase from postoperative day 6 and persist for over 18 days in affected DRG neurons . Methodologically, targeted interventions including DRG microinjection of siRNA or AAV delivery of shRNA against GPR160 have been shown to mitigate mechanical allodynia, cold, and heat hyperalgesia in bone cancer pain models . Research data indicates that tumor infiltration increases DRG neuron excitability in wild-type mice, but not in Gpr160 gene knockout mice, confirming the receptor's essential role in this pain modality .

How does CARTp interact with GPR160 to modulate pain signaling?

CARTp (cocaine- and amphetamine-regulated transcript peptide) has been identified as an endogenous ligand for GPR160 . Methodologically, researchers have demonstrated this relationship through behavioral studies showing that intrathecal or intraplantar injections of CARTp induce hypersensitivity in wild-type mice but not in Gpr160 knockout mice . This indicates that the pronociceptive effects of CARTp are mediated through GPR160. When designing experiments to study this interaction, it is important to include appropriate controls and dose-response assessments to accurately characterize the pharmacological relationship between CARTp and GPR160.

What evidence supports GPR160 as a biomarker for prostate cancer?

Research has demonstrated that GPR160 is highly expressed in prostate cancer tissue samples compared to normal prostate tissue . Methodologically, this has been validated through both in situ hybridization and immunohistochemistry analyses of prostate samples obtained from patients undergoing prostatectomy . Specifically, studies have successfully assessed GPR160 expression in 199 samples using RNAscope® and 158 samples using immunohistochemistry . When investigating GPR160 as a biomarker, researchers should employ multiple detection methods and correlate expression levels with clinical parameters to establish diagnostic or prognostic value.

How does modulation of GPR160 expression affect cancer cell biology?

Knockdown of GPR160 using lentivirus-mediated short hairpin RNA constructs targeting the human GPR160 gene (ShGPR160) has been shown to result in prostate cancer cell apoptosis and growth arrest both in vitro and in athymic mice . Methodologically, researchers investigating GPR160's role in cancer should employ both in vitro cell culture systems and in vivo xenograft models to comprehensively characterize its effects on cancer cell proliferation, apoptosis, migration, and invasion. Controls should include scrambled shRNA constructs and rescue experiments to confirm specificity.

What are the methodological considerations for assessing GPR160 expression in patient-derived tumor samples?

When assessing GPR160 expression in clinical samples, researchers should employ multiple complementary techniques. Based on published methodologies, in situ hybridization using RNAscope® technology and immunohistochemistry have been successfully applied to detect GPR160 in patient-derived prostate cancer samples . Researchers should include appropriate positive and negative controls, use standardized scoring systems, and correlate expression with clinicopathological parameters. Additionally, specimen handling, fixation methods, and antigen retrieval techniques can significantly impact detection sensitivity and should be optimized and standardized across samples.

What are the optimal methods for generating and validating GPR160 knockout models?

To generate GPR160 knockout models, CRISPR-Cas9 genome editing technology has been successfully employed . Methodologically, researchers should design guide RNAs targeting conserved regions of the GPR160 gene, verify deletions through genomic PCR and sequencing, and validate functional knockout by assessing mRNA and protein expression. Importantly, thorough phenotypic characterization is necessary - published data shows that Gpr160 knockout mice are healthy and fertile with no observable physical abnormalities, though they display altered nociceptive responses in specific pain models . When designing knockout experiments, researchers should include appropriate wild-type and floxed controls matched for age, sex, and genetic background.

What techniques are most effective for studying GPR160 transcriptional regulation?

Research has revealed that GPR160 expression is regulated by histone modifications and transcription factor binding . Methodologically, chromatin immunoprecipitation (ChIP) assays have been effective in demonstrating reduced H3K27me3 (repressive mark) and increased H3K27ac (activating mark) modifications at the GPR160 promoter region following tumor infiltration in bone cancer pain models . Additionally, ChIP assays have confirmed enhanced binding of the transcription factor Sp1 to the GPR160 gene promoter region in response to tumor infiltration . Researchers investigating transcriptional regulation should combine these approaches with reporter gene assays and site-directed mutagenesis to comprehensively characterize regulatory elements.

How can GPR160 activity be monitored in real-time in cellular systems?

Electrophysiological approaches such as whole-cell patch-clamp recordings have been effectively used to assess the functional consequences of GPR160 activation or inhibition on neuronal excitability . Research data shows that GPR160 overexpression in DRG neurons results in reduced action potential threshold and rheobase, along with increased action potential frequency . Complementary approaches might include calcium imaging, BRET/FRET-based assays to monitor receptor-effector coupling, and phosphorylation-specific antibodies to detect activation of downstream signaling molecules. When designing such experiments, researchers should include appropriate positive controls and time-course analyses to capture both rapid and delayed signaling events.

What approaches can resolve contradictions in GPR160 functional data between different experimental models?

When addressing contradictory data across experimental models, researchers should systematically analyze potential variables including species differences, tissue-specific expression patterns, and methodology variations. For instance, while GPR160 knockout prevents neuropathic pain development in mice , the specific cellular mechanisms may differ between neuropathic pain and bone cancer pain models . Methodologically, researchers should employ cross-validation using multiple complementary approaches (genetic, pharmacological, behavioral) and carefully control for confounding variables including age, sex, genetic background, and environmental conditions. Multi-center collaborative studies with standardized protocols can help resolve contradictions.

How might GPR160-targeted therapies be developed for pain management?

Based on research showing that GPR160 knockout or knockdown prevents pain hypersensitivity in neuropathic and bone cancer pain models , targeted therapies could focus on inhibiting GPR160 expression or function. Methodologically, researchers could pursue several approaches: (1) small molecule antagonists designed to block CARTp binding to GPR160, (2) biologics such as antibodies targeting the extracellular domains of GPR160, or (3) genetic approaches using antisense oligonucleotides or RNA interference to reduce GPR160 expression. When developing such therapies, researchers should assess both efficacy in pain relief and potential side effects, particularly given GPR160's expression in prostate cancer cells .

What are the methodological challenges in studying GPR160's dual roles in pain and cancer?

Studying GPR160's involvement in both pain processing and cancer biology presents unique challenges. Researchers must design experiments that can distinguish between effects on tumor progression versus pain sensation, particularly in cancer pain models. Methodologically, this requires sophisticated approaches such as conditional knockout models (e.g., tissue-specific or inducible systems) that allow temporal and spatial control of GPR160 expression. Additionally, researchers should combine behavioral assessments of pain with molecular and cellular analyses of tumor growth and metastasis. The development of selective pharmacological tools (agonists and antagonists) would facilitate mechanistic studies by allowing acute, reversible modulation of GPR160 function in different experimental contexts.