Fpr3

Formyl peptide receptor-related sequence 1 (FMLP-related receptor I) (FMLP-R-I) (Formyl peptide receptor related sequence 1) (Formyl peptide receptor-like 1) (Lipoxin A4 receptor) (LXA4 receptor) (N-f

Spatial tier: RESTRICTED · Class: GPCR · Top region: AD (Anterodorsal nucleus) · Positive regions: 14/554

43.0Discovery Score
33.8Targetability Score
CEvidence grade C
What this means: Fpr3: fine CCF profile is restricted toward AD (top regions: AD, LC, SNc, ENTm5, ENTm3; 14 positive regions); direct spatial validation is still required.

Function in AD: evidence, prediction, innovation

Gene function
Fpr3 (Fpr-rs1) encodes a formyl peptide receptor, a Gi-coupled GPCR related to the chemoattractant receptors that detect bacterial N-formylated peptides. In mouse it is expressed by subsets of vomeronasal sensory neurons, bone-marrow cells and neutrophils and is upregulated by lipopolysaccharide; bacterial MgrB is a validated agonist.
Region function
The anterodorsal thalamic nucleus carries the head-direction signal from vestibular nuclei to parahippocampal cortex, underpinning spatial orientation and navigation.
Published in this region
none No region-specific literature found. Fpr3 protein has been mapped to vomeronasal sensory neurons and immune cells (Stempel et al. 2016), where bacterial MgrB peptide activates it and drives avoidance behaviour (Bufe et al. 2019), with no CNS neuronal expression reported.
Predicted function
Prediction: an Fpr3-positive AD population would most plausibly provide Gi-coupled inhibition damping head-direction firing during systemic infection, a route by which sickness degrades spatial orientation; alternatively the signal reflects perivascular immune cells. First test: anti-Fpr3 immunostaining with neuronal markers; MgrB should suppress AD firing if neuronal Fpr3 is real. Strain background matters, since many inbred strains carry a non-functional allele.
Innovation
★★★★☆ 4/5 A pathogen-sensing GPCR in the head-direction thalamus would be genuinely novel, and antibodies plus natural knockout strains make it cheap to test.
Tools
validated anti-Fpr3 antibodies (Stempel et al. 2016); natural knockout strains carrying the Fpr3 delta424-435 allele as controls; MgrB peptide agonist; antagonists Boc-MLF and WRW4 for related Fprs.
References

Direct evidence located at the region

No Allen ISH section could be located at this region's centroid for the recorded experiments.

Look it up yourself: Allen Mouse Brain ISH for Fpr3Allen reference atlas: AD (structure 64)ABC Atlas MERFISH viewer(in the ABC Atlas choose dataset MERFISH-C57BL6J-638850-CCF, colour cells by gene "Fpr3" or by parcellation_substructure "AD")All genes confined to AD + 3-D brain

Direct spatial evidence

MERFISH REGION LOCATOR
AD MERFISH region locator
Real single-cell MERFISH coordinates for the AD (Anterodorsal nucleus) section -- our own ground-truth data, showing exactly where this region sits, independent of whether the Allen ISH section below is easy to read.

Regional expression figure

Fpr3 regional expression profile

Predicted WMB × fine-CCF profile; not direct full-transcriptome spatial measurement.

Spatial profile

AD
0.219
LC
0.174
SNc
0.159
ENTm5
0.156
ENTm3
0.143
CU
0.136
IAD
0.135
PVT
0.134
EW
0.129
PMv
0.128
RL
0.128
DR
0.127
ADP
0.124
VTA
0.124
VISpm6b
0.121
MMp
0.121
ACAv5
0.121
PL2/3
0.12
VISli6b
0.119
ENTm6
0.119

Evidence and specificity

Evidence status
PREDICTED_FINE
Direct sources
None; predicted localization only
Exclusive threshold
12 positive regions out of 554
Spatial specificity
0.302
Top-region fraction
0.073
Filter status
PASS

Interpretation limits