P2rx6

P2X purinoceptor 6 (P2X6) (ATP receptor) (P2XM) (Purinergic receptor) (Purinergic receptor P2X-like 1)

Spatial tier: RESTRICTED · Class: ION_CHANNEL · Top region: SCO (Subcommissural organ) · Positive regions: 16/554

48.2Discovery Score
42.8Targetability Score
CEvidence grade C
What this means: P2rx6: fine CCF profile is restricted toward SCO (top regions: SCO, OV, V, III, VI; 16 positive regions); direct spatial validation is still required.

Function in SCO: evidence, prediction, innovation

Gene function
P2rx6 encodes the P2X6 subunit of the ATP-gated P2X family of trimeric cation channels. Uniquely among P2X subunits it cannot form functional homomeric channels: an uncharged region in its N-terminus keeps it in the endoplasmic reticulum unless it partners P2X2 or P2X4. It therefore acts as a modulatory subunit that tunes the kinetics, ATP sensitivity and trafficking of heteromeric P2X receptors.
Region function
The subcommissural organ is a tiny ependymal secretory gland at the entrance of the cerebral aqueduct beneath the posterior commissure; it releases SCO-spondin into the CSF, where it condenses into Reissner's fibre, and its failure causes aqueductal stenosis and hydrocephalus.
Published in this region
inferred No region-specific literature found. P2X6 mRNA is widespread in brain and its trafficking and assembly biology have been worked out in cultured neurons and heterologous cells (Bobanovic 2002; Ormond 2006; Barrera 2007; reviewed by North 2002). Purinergic signalling is prominent in ependyma and choroid plexus, which is the closest cell-type parallel, but no SCO-specific study exists.
Predicted function
Prediction: ATP is released into CSF by ependymal and choroid-plexus cells, so P2X6 in SCO ependymocytes would most plausibly join P2X2 or P2X4 heteromers to form an ATP-gated calcium entry pathway coupling CSF purine levels to secretory activity and ciliary beating. Because P2X6 is only modulatory, knockout should shift the ATP concentration-response and kinetics of SCO purinergic responses rather than abolish them. The clean test is P2X antagonists (PPADS, suramin, TNP-ATP) applied to SCO explants with SCO-spondin secretion and ciliary beat frequency as readouts.
Innovation
★★★★☆ 4/5 Purinergic control of the subcommissural organ is unexplored despite ATP being an obvious CSF-borne signal and the pharmacology being off-the-shelf.
Tools
P2rx6 knockout mice; broad P2X antagonists PPADS, suramin and TNP-ATP; agonists ATP and alpha,beta-methylene-ATP; anti-P2X6 antibodies; FoxJ1-CreER (JAX 027012) for ependymal conditional deletion; no P2rx6-Cre line.
References

Direct evidence located at the region

P2rx6 Allen ISH at the CCF centroid of SCO

Allen ISH experiment 75551463, section image 75488842 (section 229): the section that contains the CCF centroid of Subcommissural organ according to the Allen image-to-atlas alignment (reference_to_image), with a 2 mm window around that point. Left: whole section, red box = window. Middle: ISH signal. Right: Allen's expression-mask view of the same window. open this image in the Allen viewer

Look it up yourself: Allen Mouse Brain ISH for P2rx6Allen reference atlas: SCO (structure 599626923)ABC Atlas MERFISH viewer(in the ABC Atlas choose dataset MERFISH-C57BL6J-638850-CCF, colour cells by gene "P2rx6" or by parcellation_substructure "SCO")All genes confined to SCO + 3-D brain

Direct spatial evidence

MERFISH REGION LOCATOR
SCO MERFISH region locator
Real single-cell MERFISH coordinates for the SCO (Subcommissural organ) 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

P2rx6 regional expression profile

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

Spatial profile

SCO
1.88
OV
1.86
V
1.35
III
1.33
VI
1.13
AP
0.988
PVi
0.977
PVpo
0.872
SFO
0.75
AD
0.649
I5
0.622
XII
0.617
VII
0.613
DMX
0.612
ME
0.547
PVp
0.533
RSPd2/3
0.484
PVa
0.468
RSPv2/3
0.418
MEPO
0.392

Evidence and specificity

Evidence status
PREDICTED_FINE
Direct sources
None; predicted localization only
Exclusive threshold
12 positive regions out of 554
Spatial specificity
0.411
Top-region fraction
0.093
Filter status
PASS

Interpretation limits