Expression of other chemosensors in human tissues.

<p>TAARs show very weak or no expression in the investigated tissues, while the taste receptors TAS1R and TAS2R show detectable expression across the investigated tissues. The vomeronasal receptors (VN1R), namely VN1R1, show a widespread expression pattern.</p

Summary of RNA-Seq data.

<p>Summary of RNA-Seq data.</p

Detection of weakly and highly expressed ORs with RNA-Seq. A:

<p>Sample representation of read coverage of weakly and highly expressed ORs detected in the prostate and visualized by the Integrative Genomic Viewer. The gray segments indicate reads that were mapped onto the reference genome. The gene is indicated by black bars (exon) and thin lines (intron). Above, the read coverage is shown (detected and mapped counts/bases at each respective position). <b>B:</b> Each bar represents the number of OR genes (black) or OR pseudogenes (gray) that were expressed in one of the 16 investigated tissues with an FPKM value >0.1. The largest number of ORs were detected in testis, brain and ovary; only a few ORs were detected in skeletal muscle and liver. <b>C:</b> The bar diagram shows the number of ORs exclusively expressed in each tissue. Exclusively expressed ORs have greater FPKM values than 0.1 in the tissue indicated and are expressed at FPKM values lower than 0.1 in all other tissues. Testis had the greatest number of exclusively expressed ORs. In skeletal muscle, no exclusively expressed ORs were detected.</p

Expression of signaling pathway components across tissues.

<p>Expression analysis of signaling components including, Gα_olf (GNAL), adenylyl cyclase III (ADCY3), CNG channel subunits (CNGA2, CNGA4 and CNGB1), calcium-activated chloride channel (ANO2) and the nucleotide exchange factor Ric8b (RIC8B). We also investigated the expression of accessory proteins including receptor-transporting proteins (RTP1 and RTP2) and receptor-enhancing proteins 1 (REEP1), as well as the expression of the olfactory marker protein (OMP), a specific marker for olfactory sensory neurons.</p

Analysis of OR transcripts across tissues. A:

<p>Analysis of the 20 most highly expressed ORs (summed FPKM >1). The graphic illustrates the presence of detected chimeric transcripts or unannotated untranslated regions in the upstream areas of the respective OR ORF. <b>B:</b> Overview of detected internal splicing events within the ORF of the 20 most highly expressed ORs. The heat map indicates the level of expression of the respective receptor and the detected internal splicing events (red frames). <b>C:</b> Schematic representation of detected internal splicing events of the broadly expressed OR51E1 and the testis-specific OR4N4.</p

Pattern of expression of OR pseudogenes in different tissues.

<p>All OR pseudogenes with summed FPKM values >0.5 across all 16 from Body Map 2.0 are listed. The color intensity represents the FPKM value. Of the expressed pseudogenes, 58% belong to the 7E subfamily; genes in this family are indicated by bold letters.</p

Expression Profile of Ectopic Olfactory Receptors Determined by Deep Sequencing

<div><p>Olfactory receptors (ORs) provide the molecular basis for the detection of volatile odorant molecules by olfactory sensory neurons. The OR supergene family encodes G-protein coupled proteins that belong to the seven-transmembrane-domain receptor family. It was initially postulated that ORs are exclusively expressed in the olfactory epithelium. However, recent studies have demonstrated ectopic expression of some ORs in a variety of other tissues. In the present study, we conducted a comprehensive expression analysis of ORs using an extended panel of human tissues. This analysis made use of recent dramatic technical developments of the so-called Next Generation Sequencing (NGS) technique, which encouraged us to use open access data for the first comprehensive RNA-Seq expression analysis of ectopically expressed ORs in multiple human tissues. We analyzed mRNA-Seq data obtained by Illumina sequencing of 16 human tissues available from Illumina Body Map project 2.0 and from an additional study of OR expression in testis. At least some ORs were expressed in all the tissues analyzed. In several tissues, we could detect broadly expressed ORs such as OR2W3 and OR51E1. We also identified ORs that showed exclusive expression in one investigated tissue, such as OR4N4 in testis. For some ORs, the coding exon was found to be part of a transcript of upstream genes. In total, 111 of 400 OR genes were expressed with an FPKM (fragments per kilobase of exon per million fragments mapped) higher than 0.1 in at least one tissue. For several ORs, mRNA expression was verified by RT-PCR. Our results support the idea that ORs are broadly expressed in a variety of tissues and provide the basis for further functional studies.</p> </div

Chimeric transcripts of different ectopically expressed ORs in various tissues

<p>. <b>A:</b> The table shows expression values for four different ORs and their respective nearby genes in various tissues. Corresponding chimeric transcripts could be detected in different tissues. <b>B:</b> PCR experiments confirmed the observed chimeric transcripts of these ORs. OR2W3 shares chimeric transcripts with the Trim58 gene, while OR2A7 shares chimeric transcripts with part of loc728377. In testis only, OR4N4 shows chimeric transcripts with the loc727924 gene. The OR pseudogene OR7E14P yield chimeric transcripts with the Plekha7 gene. We confirmed the amplified PCR products by Sanger sequencing. <b>C:</b> Schematic representation of the detected chimeric transcripts of Trim58 with OR2W3 and OR2T8. RNA-Seq of thyroid tissue reveals a complex splice pattern (red arcs) leading to chimeric transcripts of Trim58 and OR2W3 or OR2T8 as well as chimeric transcripts of OR2W3 with OR2T8. The green arrows indicate ORFs. Depending on the used splice sites, the reading frame of the odorant receptor can, in principle, be intact or fused to the Trim58 reading frame. <b>D:</b> Splicing between the uncharacterized loc727924 gene and the OR4N4 or OR4N3P in testis. Parts of the coding exon of OR4M2 gene overlap with exons of the loc727924 gene. <b>E:</b> Chimeric transcripts of OR2A7 and loc728377 in kidney. The coding exon of OR2A7 overlaps with exon 13 of the loc728377 gene.</p

Expression of ORs in testis. A:

<p>Expression profile for the 60 most highly expressed OR genes and pseudogenes in two testis samples, sorted by FPKM values of Testis 2. <b>B:</b> Plotted expression pattern correlation for all detected ORs in two testis samples. R² is the coefficient of determination. <b>C:</b> Venn diagram showing the intersection of OR transcripts detected in two independent RNA-Seqs of human testis (FPKM >0.1). In both RNA-Seq analyses, we detected 36 identical ORs. (Testis 1 = Body Map 2.0; Testis 2 = Wang et al., 2008).</p

Expression pattern of ectopically expressed ORs.

<p>The heat map shows FPKM values for the 40 most highly expressed ORs found in the human tissues studied. Dark blue indicates high expression (FPKM values higher than 3), and white indicates no expression. ORs are sorted by the sum of their expression values across all tissues.</p