Atypical expansion in mice of the sensory neuron-specific Mrg G protein-coupled receptor family

doi:10.1073/pnas.1732949100

Atypical expansion in mice of the sensory neuron-specific Mrg G protein-coupled receptor family

^*Division of Biology, 216-76, and ^†Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125

Edited by Melvin I. Simon, California Institute of Technology, Pasadena, CA, and approved July 1, 2003 (received for review May 15, 2003)

Abstract

The Mas-related genes (Mrgs) comprise a family of >50 G protein-coupled receptors (GPCRs), many of which are expressed in specific subsets of nociceptive sensory neurons in mice. In contrast, humans contain a related but nonorthologous family of genes, called MrgXs or sensory neuron-specific receptors, of which many fewer appear to be expressed in sensory neurons. To determine whether the diversity of murine Mrgs is generic to rodents or is an atypical feature of mice, we characterized MrgA, MrgB, MrgC, and MrgD subfamilies in rat and gerbil. Surprisingly, although mice have ≈22 MrgA and ≈14 MrgC genes, rats and gerbils have just a single MrgA and MrgC gene. This murine-specific expansion likely reflects recent retrotransposon-mediated unequal crossover events. The expression of Mrgs in rat sensory ganglia suggests that the extensive cellular diversity in mice can be simplified to a core subset of approximately four different genes (MrgA, MrgB, MrgC, and MrgD), defining a similar number of neuronal subpopulations. Our results suggest more generally that mouse–human genomic comparisons may sometimes reveal differences atypical of rodents.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: wuwei{at}caltech.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: Mrgs, Mas-related genes; SNSR, sensory neuron-specific receptors; GPCR, G protein-coupled receptor; MYA, million years ago; DRG, dorsal root ganglia; GDNF, glial cell line-derived neurotrophic factor.
Data deposition: The sequences described in this paper have been deposited in the GenBank database [accession nos. AF518238 –AF518249, AY266420 (rat Mrgs), and AY196926 –AY196928 (partial sequences for gerbil MrgB1, MrgB4, and MrgD)].