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CD36 is involved in oleic acid detection by the murine olfactory system.

Oberland S, Ackels T, Gaab S, Pelz T, Spehr J, Spehr M, Neuhaus EM - Front Cell Neurosci (2015)

Bottom Line: In accordance with the described roles of CD36 as fatty acid receptor or co-receptor in other sensory systems, the number of olfactory neurons responding to oleic acid, a major milk component, in Ca(2+) imaging experiments is drastically reduced in young CD36 knock-out mice.Strikingly, we also observe marked age-dependent changes in CD36 localization, which is prominently present in the ciliary compartment only during the suckling period.Our results support the involvement of CD36 in fatty acid detection by the mammalian olfactory system.

View Article: PubMed Central - PubMed

Affiliation: Pharmacology and Toxicology, University Hospital Jena, Friedrich-Schiller-University Jena Jena, Germany ; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin Berlin, Germany ; Freie Universität-Berlin, Fachbereich Biologie, Chemie und Pharmazie Berlin, Germany.

ABSTRACT
Olfactory signals influence food intake in a variety of species. To maximize the chances of finding a source of calories, an animal's preference for fatty foods and triglycerides already becomes apparent during olfactory food search behavior. However, the molecular identity of both receptors and ligands mediating olfactory-dependent fatty acid recognition are, so far, undescribed. We here describe that a subset of olfactory sensory neurons expresses the fatty acid receptor CD36 and demonstrate a receptor-like localization of CD36 in olfactory cilia by STED microscopy. CD36-positive olfactory neurons share olfaction-specific transduction elements and project to numerous glomeruli in the ventral olfactory bulb. In accordance with the described roles of CD36 as fatty acid receptor or co-receptor in other sensory systems, the number of olfactory neurons responding to oleic acid, a major milk component, in Ca(2+) imaging experiments is drastically reduced in young CD36 knock-out mice. Strikingly, we also observe marked age-dependent changes in CD36 localization, which is prominently present in the ciliary compartment only during the suckling period. Our results support the involvement of CD36 in fatty acid detection by the mammalian olfactory system.

No MeSH data available.


Related in: MedlinePlus

CD36 neurons express olfactory signal transduction proteins. (A–D) Confocal images of dissociated olfactory sensory neurons from P8 animals. Immunostainings show co-expression of CD36 (green) and Gαolf(A), ACIII (B), CNGA2 (C), and ANO2 (D) (red). (E) Normalized CD36 read counts (Trimmed Mean of M-values (TMM) method) for both cell fractions CD36-depleted (CD36-dep) and CD36-enriched (CD36-enr) used for transcriptome sequencing. Diagram illustrates the enhancement of CD36 (3.4 fold) in the CD36-enriched fraction (257.5) compared to the CD36-depleted fraction (75.7). (F) Quantitative real-time PCR results for Gαolf, ACIII, CNGA2, and ANO2 comparing CD36-enriched and CD36-depleted cell fraction from magnetic CD36 cell sorting in P8 animals. Data was normalized to OMP. Scale bars: 5 μm (A–D).
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Figure 4: CD36 neurons express olfactory signal transduction proteins. (A–D) Confocal images of dissociated olfactory sensory neurons from P8 animals. Immunostainings show co-expression of CD36 (green) and Gαolf(A), ACIII (B), CNGA2 (C), and ANO2 (D) (red). (E) Normalized CD36 read counts (Trimmed Mean of M-values (TMM) method) for both cell fractions CD36-depleted (CD36-dep) and CD36-enriched (CD36-enr) used for transcriptome sequencing. Diagram illustrates the enhancement of CD36 (3.4 fold) in the CD36-enriched fraction (257.5) compared to the CD36-depleted fraction (75.7). (F) Quantitative real-time PCR results for Gαolf, ACIII, CNGA2, and ANO2 comparing CD36-enriched and CD36-depleted cell fraction from magnetic CD36 cell sorting in P8 animals. Data was normalized to OMP. Scale bars: 5 μm (A–D).

Mentions: We tested whether and, if so, which members of the olfactory transduction machinery are expressed in CD36-positive sensory neurons. Immunostaining of four canonical olfactory transduction proteins, Gαolf, ACIII, CNGA2, and ANO2, in dissociated olfactory neurons demonstrated co-expression in CD36-positive cells (Figures 4A–D). To further uncover the expression of signaling proteins in CD36-positive neurons, we performed quantitative real-time PCR and transcriptome sequencing. Dissociated neurons were sorted via a magnetic cell separation system, yielding in a fraction enriched in CD36 expressing neurons (Figure 4E). Quantitative real-time PCR of the sorted neurons confirmed the expression of Gαolf, ACIII, CNGA2, and ANO2 (Figure 4F). Also transcriptome sequencing of the CD36-enriched fraction showed transcripts for Gαolf, ACIII, CNGA2, and ANO2 together with mRNAs from other elements of the canonical olfactory signaling cascade (Gβ1, Gγ13, CNGA4, CNGB1, PDE1C, PDE4A, NKCC1, NCKX4, RTP1, RTP2, REEP1; Supplementary Table 1). To exclude proteins with low abundance, analysis was restricted to transcripts that showed both an expression level of at least 0.1% of ACIII. The transcriptome dataset from CD36 expressing neurons further showed expression of ORs, but not of TAARs or GUCY2D, the particulate guanylate cyclase expressed in CO2 responsive olfactory neurons.


CD36 is involved in oleic acid detection by the murine olfactory system.

Oberland S, Ackels T, Gaab S, Pelz T, Spehr J, Spehr M, Neuhaus EM - Front Cell Neurosci (2015)

CD36 neurons express olfactory signal transduction proteins. (A–D) Confocal images of dissociated olfactory sensory neurons from P8 animals. Immunostainings show co-expression of CD36 (green) and Gαolf(A), ACIII (B), CNGA2 (C), and ANO2 (D) (red). (E) Normalized CD36 read counts (Trimmed Mean of M-values (TMM) method) for both cell fractions CD36-depleted (CD36-dep) and CD36-enriched (CD36-enr) used for transcriptome sequencing. Diagram illustrates the enhancement of CD36 (3.4 fold) in the CD36-enriched fraction (257.5) compared to the CD36-depleted fraction (75.7). (F) Quantitative real-time PCR results for Gαolf, ACIII, CNGA2, and ANO2 comparing CD36-enriched and CD36-depleted cell fraction from magnetic CD36 cell sorting in P8 animals. Data was normalized to OMP. Scale bars: 5 μm (A–D).
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Figure 4: CD36 neurons express olfactory signal transduction proteins. (A–D) Confocal images of dissociated olfactory sensory neurons from P8 animals. Immunostainings show co-expression of CD36 (green) and Gαolf(A), ACIII (B), CNGA2 (C), and ANO2 (D) (red). (E) Normalized CD36 read counts (Trimmed Mean of M-values (TMM) method) for both cell fractions CD36-depleted (CD36-dep) and CD36-enriched (CD36-enr) used for transcriptome sequencing. Diagram illustrates the enhancement of CD36 (3.4 fold) in the CD36-enriched fraction (257.5) compared to the CD36-depleted fraction (75.7). (F) Quantitative real-time PCR results for Gαolf, ACIII, CNGA2, and ANO2 comparing CD36-enriched and CD36-depleted cell fraction from magnetic CD36 cell sorting in P8 animals. Data was normalized to OMP. Scale bars: 5 μm (A–D).
Mentions: We tested whether and, if so, which members of the olfactory transduction machinery are expressed in CD36-positive sensory neurons. Immunostaining of four canonical olfactory transduction proteins, Gαolf, ACIII, CNGA2, and ANO2, in dissociated olfactory neurons demonstrated co-expression in CD36-positive cells (Figures 4A–D). To further uncover the expression of signaling proteins in CD36-positive neurons, we performed quantitative real-time PCR and transcriptome sequencing. Dissociated neurons were sorted via a magnetic cell separation system, yielding in a fraction enriched in CD36 expressing neurons (Figure 4E). Quantitative real-time PCR of the sorted neurons confirmed the expression of Gαolf, ACIII, CNGA2, and ANO2 (Figure 4F). Also transcriptome sequencing of the CD36-enriched fraction showed transcripts for Gαolf, ACIII, CNGA2, and ANO2 together with mRNAs from other elements of the canonical olfactory signaling cascade (Gβ1, Gγ13, CNGA4, CNGB1, PDE1C, PDE4A, NKCC1, NCKX4, RTP1, RTP2, REEP1; Supplementary Table 1). To exclude proteins with low abundance, analysis was restricted to transcripts that showed both an expression level of at least 0.1% of ACIII. The transcriptome dataset from CD36 expressing neurons further showed expression of ORs, but not of TAARs or GUCY2D, the particulate guanylate cyclase expressed in CO2 responsive olfactory neurons.

Bottom Line: In accordance with the described roles of CD36 as fatty acid receptor or co-receptor in other sensory systems, the number of olfactory neurons responding to oleic acid, a major milk component, in Ca(2+) imaging experiments is drastically reduced in young CD36 knock-out mice.Strikingly, we also observe marked age-dependent changes in CD36 localization, which is prominently present in the ciliary compartment only during the suckling period.Our results support the involvement of CD36 in fatty acid detection by the mammalian olfactory system.

View Article: PubMed Central - PubMed

Affiliation: Pharmacology and Toxicology, University Hospital Jena, Friedrich-Schiller-University Jena Jena, Germany ; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin Berlin, Germany ; Freie Universität-Berlin, Fachbereich Biologie, Chemie und Pharmazie Berlin, Germany.

ABSTRACT
Olfactory signals influence food intake in a variety of species. To maximize the chances of finding a source of calories, an animal's preference for fatty foods and triglycerides already becomes apparent during olfactory food search behavior. However, the molecular identity of both receptors and ligands mediating olfactory-dependent fatty acid recognition are, so far, undescribed. We here describe that a subset of olfactory sensory neurons expresses the fatty acid receptor CD36 and demonstrate a receptor-like localization of CD36 in olfactory cilia by STED microscopy. CD36-positive olfactory neurons share olfaction-specific transduction elements and project to numerous glomeruli in the ventral olfactory bulb. In accordance with the described roles of CD36 as fatty acid receptor or co-receptor in other sensory systems, the number of olfactory neurons responding to oleic acid, a major milk component, in Ca(2+) imaging experiments is drastically reduced in young CD36 knock-out mice. Strikingly, we also observe marked age-dependent changes in CD36 localization, which is prominently present in the ciliary compartment only during the suckling period. Our results support the involvement of CD36 in fatty acid detection by the mammalian olfactory system.

No MeSH data available.


Related in: MedlinePlus