Comparative Embryonic Spatio-Temporal Expression Profile Map of the Xenopus P2X Receptor Family

Camille Blanchard, Eric Boué-Grabot, Karine Massé
Front. Cell. Neurosci.. 2019-07-26; 13:
DOI: 10.3389/fncel.2019.00340

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P2X receptors are ATP-gated cations channels formed by the homo or
hetero-trimeric association from the seven cloned subunits (P2X1-7). P2X
receptors are widely distributed in different organs and cell types throughout
the body including the nervous system and are involved in a large variety of
physiological but also pathological processes in adult mammals. However, their
expression and function during embryogenesis remain poorly understood. Here, we
report the cloning and the comparative expression map establishment of the entire
P2X subunit family in the clawed frog Xenopus. Orthologous sequences for 6
mammalian P2X subunits were identified in both X. laevis and X. tropicalis, but
not for P2X3 subunit, suggesting a potential loss of this subunit in the Pipidae
family. Three of these genes (p2rx1, p2rx2, and p2rx5) exist as homeologs in the
pseudoallotetraploid X. laevis, making a total of 9 subunits in this species.
Phylogenetic analyses demonstrate the high level of conservation of these
receptors between amphibian and other vertebrate species. RT-PCR revealed that
all subunits are expressed during the development although zygotic p2rx6 and
p2rx7 transcripts are mainly detected at late organogenesis stages. Whole mount
in situ hybridization shows that each subunit displays a specific spatio-temporal
expression profile and that these subunits can therefore be grouped into two
groups, based on their expression or not in the developing nervous system.
Overlapping expression in the central and peripheral nervous system and in the
sensory organs suggests potential heteromerization and/or redundant functions of
P2X subunits in Xenopus embryos. The developmental expression of the p2rx subunit
family during early phases of embryogenesis indicates that these subunits may
have distinct roles during vertebrate development, especially embryonic

DOI: 10.3389/fncel.2019.00340
PMCID: PMC6676501
PMID: 31402854

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