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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

STED microscopy revealed receptor like localization of CD36 in olfactory cilia. (A,B) Shown are STED images of en face preparations immunostained for mOR-EG and CD36 (P8). (C,D) Higher magnifications of the cilia shown in (A,B), respectively. The olfactory receptor mOR-EG and CD36 show a similar staining pattern. (E,F) High magnification pictures showing localization of CD36 and mOR-EG in discrete spots (examples are indicated by arrowheads). (G,H) STED images of dissociated adult neurons immunostained for acetylated tubulin (ac. tub). Scale bars: 1 μm (A–D,G,H), 500 nm (E,F). *Marks the dendritic knob (C,D,H).
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Figure 7: STED microscopy revealed receptor like localization of CD36 in olfactory cilia. (A,B) Shown are STED images of en face preparations immunostained for mOR-EG and CD36 (P8). (C,D) Higher magnifications of the cilia shown in (A,B), respectively. The olfactory receptor mOR-EG and CD36 show a similar staining pattern. (E,F) High magnification pictures showing localization of CD36 and mOR-EG in discrete spots (examples are indicated by arrowheads). (G,H) STED images of dissociated adult neurons immunostained for acetylated tubulin (ac. tub). Scale bars: 1 μm (A–D,G,H), 500 nm (E,F). *Marks the dendritic knob (C,D,H).

Mentions: Little is known about the spatial distribution of receptor proteins within olfactory cilia. Using stimulated emission depletion (STED) super-resolution microscopy, we recently showed that CNG channels and calcium-activated chloride channels of the Anoctamin family are localized to discrete microdomains in the ciliary membrane (Henkel et al., 2015). We here used STED microscopy to analyze mOR-EG and CD36 expression patterns in top view en face preparations (Figure 7). Similar to the ion channels, mOR-EG dissolved into distinct foci along the olfactory cilia under STED conditions (Figures 7A,C,E), while acetylated tubulin showed homogenous protein distribution (Figures 7G,H). This localization pattern provided first optical evidence for distinct spatial organization of olfactory receptors in cilia of sensory neurons. When analyzing CD36 staining pattern with STED microscopy, we found it also to be localized to discrete foci in the ciliary membrane (Figures 7B,D,F). Together, STED microscopy clearly provided morphological evidence for the organization of olfactory receptors in distinct domains along olfactory cilia. Since also the ion channels involved in odorant detection showed clustered localization pattern (Henkel et al., 2015), the presence in such microdomains seems to be a common feature of signaling proteins in olfactory cilia. The similarity in localization of CD36 is an indicator for a potential role of this fatty acid receptor in olfactory signal transduction.


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)

STED microscopy revealed receptor like localization of CD36 in olfactory cilia. (A,B) Shown are STED images of en face preparations immunostained for mOR-EG and CD36 (P8). (C,D) Higher magnifications of the cilia shown in (A,B), respectively. The olfactory receptor mOR-EG and CD36 show a similar staining pattern. (E,F) High magnification pictures showing localization of CD36 and mOR-EG in discrete spots (examples are indicated by arrowheads). (G,H) STED images of dissociated adult neurons immunostained for acetylated tubulin (ac. tub). Scale bars: 1 μm (A–D,G,H), 500 nm (E,F). *Marks the dendritic knob (C,D,H).
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Figure 7: STED microscopy revealed receptor like localization of CD36 in olfactory cilia. (A,B) Shown are STED images of en face preparations immunostained for mOR-EG and CD36 (P8). (C,D) Higher magnifications of the cilia shown in (A,B), respectively. The olfactory receptor mOR-EG and CD36 show a similar staining pattern. (E,F) High magnification pictures showing localization of CD36 and mOR-EG in discrete spots (examples are indicated by arrowheads). (G,H) STED images of dissociated adult neurons immunostained for acetylated tubulin (ac. tub). Scale bars: 1 μm (A–D,G,H), 500 nm (E,F). *Marks the dendritic knob (C,D,H).
Mentions: Little is known about the spatial distribution of receptor proteins within olfactory cilia. Using stimulated emission depletion (STED) super-resolution microscopy, we recently showed that CNG channels and calcium-activated chloride channels of the Anoctamin family are localized to discrete microdomains in the ciliary membrane (Henkel et al., 2015). We here used STED microscopy to analyze mOR-EG and CD36 expression patterns in top view en face preparations (Figure 7). Similar to the ion channels, mOR-EG dissolved into distinct foci along the olfactory cilia under STED conditions (Figures 7A,C,E), while acetylated tubulin showed homogenous protein distribution (Figures 7G,H). This localization pattern provided first optical evidence for distinct spatial organization of olfactory receptors in cilia of sensory neurons. When analyzing CD36 staining pattern with STED microscopy, we found it also to be localized to discrete foci in the ciliary membrane (Figures 7B,D,F). Together, STED microscopy clearly provided morphological evidence for the organization of olfactory receptors in distinct domains along olfactory cilia. Since also the ion channels involved in odorant detection showed clustered localization pattern (Henkel et al., 2015), the presence in such microdomains seems to be a common feature of signaling proteins in olfactory cilia. The similarity in localization of CD36 is an indicator for a potential role of this fatty acid receptor in olfactory signal transduction.

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