Landscape of GPCR expression along the mouse nephron

Abstract

Kidney transport and other renal functions are regulated by multiple G protein-coupled receptors (GPCRs) expressed along the renal tubule. The rapid, recent appearance of comprehensive unbiased gene expression data in the various renal tubule segments, chiefly RNA sequencing and protein mass spectrometry data, has provided a means of identifying patterns of GPCR expression along the renal tubule. To allow for comprehensive mapping, we first curated a comprehensive list of GPCRs in the genomes of mice, rats, and humans (https://hpcwebapps.cit.nih.gov/ESBL/Database/GPCRs/) using multiple online data sources. We used this list to mine segment-specific and cell type-specific expression data from RNA-sequencing studies in microdissected mouse tubule segments to identify GPCRs that are selectively expressed in discrete tubule segments. Comparisons of these mapped mouse GPCRs with other omics datasets as well as functional data from isolated perfused tubule and micropuncture studies confirmed patterns of expression for well-known receptors and identified poorly studied GPCRs that are likely to play roles in the regulation of renal tubule function. Thus, we provide data resources for GPCR expression across the renal tubule, highlighting both well-known GPCRs and understudied receptors to provide guidance for future studies.

Keywords: G protein-coupled receptors; nephron transport; omics.

Graphical abstract

Figure 1.

Creating a database of G protein-coupled receptors (GPCRs) and filtering for segment-specific expression. GPCR gene entries were combined from Mouse Genome Informatics (MGI), International Union of Basic and Clinical Pharmacology/British Pharmacological Society Guide to Pharmacology (IUPHAR), and Ensembl to create a complete GPCR database for mouse, rat, and human orthologs (A). This list was then mapped to RNA-sequencing (RNA-seq) data from 14 microdissected renal tubule segments (B) to get a complete picture of GPCR expression (C). From this mapped GPCR expression, segment-specific GPCRs were determined (D). These GPCRs were then compared with existing literature knowledge and cross referenced with other existing omics data sets. IMCD, inner medullary collecting duct; OMCD, outer medullary collecting duct; TPM, transcripts per kilobase million.

Figure 2.

Proximal tubule-selective G protein-coupled receptors (GPCRs). GPCR expression data from microdissected renal tubules were filtered based on an individual genes’ maximum expression [in transcripts per kilobase million (TPM)] in the initial segment of the proximal convoluted tubule (PTS1), proximal straight tubule in cortical medullary rays (PTS2), or last segment of the proximal straight tubule in the outer stripe of outer medulla (PTS3) compared with its expression in any other tubule segment. PTS1, PTS2, and PTS3 expression that was 1.5-fold greater than any other tubule segment was considered selective. Entries are sorted starting with the greatest TPM ratio. Refer to Table 3 for additional information about each GPCR. ATL, thin ascending limb of the loop of Henle; CCD, cortical collecting duct; CNT, connecting tubule; CTAL, cortical thick ascending limb of the loop of Henle; DCT, distal convoluted tubule; DTL1, short descending limb of the loop of Henle; DTL2, long descending limb of the loop of Henle in the outer medulla; DTL3, long descending limb of the loop of Henle in the inner medulla; Glom, glomerulus; IMCD, inner medullary collecting duct; MTAL, medullary thick ascending limb of the loop of Henle; OMCD, outer medullary collecting duct.

Figure 3.

Sex differences in G protein-coupled receptor (GPCR) expression in the proximal tubule. Expression data from Ransick et al. (14) were compared between males and females in the initial segment of the proximal convoluted tubule (PTS1; top) and proximal straight tubule in cortical medullary rays (PTS2; bottom). Fold changes in gene expression [male/female (M/F)] for all detected GPCRs were averaged, and a 95% confidence interval was calculated. Shown here are all GPCRs outside this confidence interval. GPCRs preferentially expressed in males are shown in blue; GPCRs preferentially expressed in females are shown in red. [Adapted from data published in Ransick et al. (14).]

Figure 4.

Thick ascending limb-selective G protein-coupled receptor (GPCRs). GPCR expression data from microdissected renal tubules were filtered based on an individual genes’ maximum expression [in transcripts per kilobase million (TPM)] in either the cortical thick ascending limb (CTAL) or medullary thick ascending limb (MTAL) compared with its expression in any other tubule segment. MTAL/CTAL expression that was 1.5-fold greater than any other tubule segment was considered selective. Entries are sorted starting with the greatest TPM ratio. Refer to Table 4 for additional information about each GPCR. ATL, thin ascending limb of the loop of Henle; CCD, cortical collecting duct; CNT, connecting tubule; DCT, distal convoluted tubule; DTL1, short descending limb of the loop of Henle; DTL2, long descending limb of the loop of Henle in the outer medulla; DTL3, long descending limb of the loop of Henle in the inner medulla; Glom, glomerulus; IMCD, inner medullary collecting duct; PTS1, initial segment of the proximal convoluted tubule; PTS2, proximal straight tubule in cortical medullary rays; PTS3, last segment of the proximal straight tubule in the outer stripe of outer medulla; OMCD, outer medullary collecting duct.

Figure 5.

Distal convoluted tubule (DCT)- and connecting tubule (CNT)-selective G protein-coupled receptor (GPCRs). GPCR expression data from microdissected renal tubules were filtered based on an individual genes’ maximum expression [in transcripts per kilobase million (TPM)] in either the DCT or CNT compared with its expression in any other tubule segment. DCT/CNT expression that was 1.5-fold greater than any other tubule segment was considered selective. Entries are sorted starting with the greatest TPM ratio. Refer to Table 5 for additional information about each GPCR. ATL, thin ascending limb of the loop of Henle; CCD, cortical collecting duct; CTAL, cortical thick ascending limb of the loop of Henle; DTL1, short descending limb of the loop of Henle; DTL2, long descending limb of the loop of Henle in the outer medulla; DTL3, long descending limb of the loop of Henle in the inner medulla; Glom, glomerulus; IMCD, inner medullary collecting duct; MTAL, medullary thick ascending limb of the loop of Henle; PTS1, initial segment of the proximal convoluted tubule; PTS2, proximal straight tubule in cortical medullary rays; PTS3, last segment of the proximal straight tubule in the outer stripe of outer medulla; OMCD, outer medullary collecting duct.

Figure 6.

Collecting duct (CD)-selective G protein-coupled receptor (GPCRs). GPCR expression data from microdissected renal tubules were filtered based on an individual genes’ maximum expression [in transcripts per kilobase million (TPM)] in either the cortical CD (CCD), outer medullary CD (OMCD), or inner medullary CD (IMCD) compared with its expression in any other tubule segment. CCD/OMCD/IMCD expression that was 1.5-fold greater than any other tubule segment was considered selective. Entries are sorted starting with the greatest TPM ratio. Refer to Table 6 for additional information about each GPCR. ATL, thin ascending limb of the loop of Henle; CNT, connecting tubule; CTAL, cortical thick ascending limb of the loop of Henle; DCT, distal convoluted tubule; DTL1, short descending limb of the loop of Henle; DTL2, long descending limb of the loop of Henle in the outer medulla; DTL3, long descending limb of the loop of Henle in the inner medulla; Glom, glomerulus; MTAL, medullary thick ascending limb of the loop of Henle; PTS1, initial segment of the proximal convoluted tubule; PTS2, proximal straight tubule in cortical medullary rays; PTS3, last segment of the proximal straight tubule in the outer stripe of outer medulla.

Figure 7.

Expression of adhesion G protein-coupled receptors along the renal tubule. Colors indicate segment boundaries. CD, collecting duct; DCT, distal convoluted tubule; DTL, descending thin limb; Glom, glomerulus; PT, proximal tubule; TAL, thick ascending limb.

Figure 8.

Expression of adrenergic receptors along the renal tubule. Colors indicate segment boundaries. CD, collecting duct; DCT, distal convoluted tubule; Glom, glomerulus; DTL, descending thin limb; PT, proximal tubule; TAL, thick ascending limb.

Figure 9.

Expression of lysophosphatidic acid receptors (LPARs) along the renal tubule. Colors indicate segment boundaries. CD, collecting duct; DCT, distal convoluted tubule; Glom, glomerulus; DTL, descending thin limb; PT, proximal tubule; TAL, thick ascending limb.