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Analysis of the protein related receptor GPR92 in G-cells.

Rettenberger AT, Schulze W, Breer H, Haid D - Front Physiol (2015)

Bottom Line: Our previous studies have shown that G-cells express suitable receptor types, most notably the peptone-receptor GPR92 and the amino acid receptors GPRC6A and CaSR; however, their relative importance remained unclear.The results indicate that the relative amount of receptor protein for GPR92 was much higher than for the receptor types GPRC6A and CaSR.These findings support the notion that the peptone-receptor GPR92 may be particularly relevant for sensing partially digested protein products.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiology, University of Hohenheim Stuttgart, Germany.

ABSTRACT
A continuous assessment of ingested food in the gastric lumen is essential for fine-tuning the digestive activities, including the secretion of the regulatory hormones such as gastrin. It has been proposed that G-cells may be able to sense the amount of ingested proteins and adjust the secretion of gastrin accordingly. Our previous studies have shown that G-cells express suitable receptor types, most notably the peptone-receptor GPR92 and the amino acid receptors GPRC6A and CaSR; however, their relative importance remained unclear. To determine the relative quantity of each receptor type, individual G-cells isolated from the transgenic mouse line mGas-EGFP were analyzed by means of a Liquid Chromatography Tandem-Mass Spectrometry (LC-MS/MS) procedure. The results indicate that the relative amount of receptor protein for GPR92 was much higher than for the receptor types GPRC6A and CaSR. These findings support the notion that the peptone-receptor GPR92 may be particularly relevant for sensing partially digested protein products. This view was supported by the finding that a high-protein diet affected the expression level of the peptone-receptor GPR92 in the gastric antrum as well as in the circumvallate papillae.

No MeSH data available.


Related in: MedlinePlus

EGFP-positive G-cells of transgenic mGas-EGFP mice. (A,B) A longitudinal tissue section through the gastric antrum of an mGas-EGFP mouse. G-cells are visible by their strong intrinsic EGFP-fluorescence (green). Sections are counterstained with DAPI (blue). (C) After tissue dissociation EGFP-positive G-cells (green) retain their intrinsic fluorescence and can easily be distinguished from non-labeled cell types. Scale bars: (A,B), 50 μm; (C), 20 μm.
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Figure 2: EGFP-positive G-cells of transgenic mGas-EGFP mice. (A,B) A longitudinal tissue section through the gastric antrum of an mGas-EGFP mouse. G-cells are visible by their strong intrinsic EGFP-fluorescence (green). Sections are counterstained with DAPI (blue). (C) After tissue dissociation EGFP-positive G-cells (green) retain their intrinsic fluorescence and can easily be distinguished from non-labeled cell types. Scale bars: (A,B), 50 μm; (C), 20 μm.

Mentions: Since the mRNA-levels provide only a first approximation concerning the amounts of the actual proteins, attempts were made to determine the relative protein concentration for the three receptor types in G-cells. Such an approach is only possible by means of advanced mass spectrometry methodology and requires isolated cells. Therefore, a procedure was established that allowed to selectively isolating antral G-cells from GFP-BAC transgenic mice (mGas-EGFP) in which G-cells can be identified by their cell-specific strong EGFP-fluorescence (Takaishi et al., 2011). A typical section through the gastric antrum of such a transgenic mouse is depicted in Figures 2A,B; G-cells exhibit a bright intrinsic EGFP-fluorescence. Using these transgenic animals, we have developed a protocol for a mild tissue dissociation which allowed to manually isolate EGFP-positive G-cells by means of micropipettes and micromanipulators under microscopic surveillance (described in the Materials and Methods Section). A typical cell suspension from antral tissue is shown in Figure 2C. Since the EGFP-positive G-cells retain their intrinsic fluorescence during the dissociation process they could be easily distinguished from non-labeled cells and selectively picked out of the cell suspension.


Analysis of the protein related receptor GPR92 in G-cells.

Rettenberger AT, Schulze W, Breer H, Haid D - Front Physiol (2015)

EGFP-positive G-cells of transgenic mGas-EGFP mice. (A,B) A longitudinal tissue section through the gastric antrum of an mGas-EGFP mouse. G-cells are visible by their strong intrinsic EGFP-fluorescence (green). Sections are counterstained with DAPI (blue). (C) After tissue dissociation EGFP-positive G-cells (green) retain their intrinsic fluorescence and can easily be distinguished from non-labeled cell types. Scale bars: (A,B), 50 μm; (C), 20 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4585063&req=5

Figure 2: EGFP-positive G-cells of transgenic mGas-EGFP mice. (A,B) A longitudinal tissue section through the gastric antrum of an mGas-EGFP mouse. G-cells are visible by their strong intrinsic EGFP-fluorescence (green). Sections are counterstained with DAPI (blue). (C) After tissue dissociation EGFP-positive G-cells (green) retain their intrinsic fluorescence and can easily be distinguished from non-labeled cell types. Scale bars: (A,B), 50 μm; (C), 20 μm.
Mentions: Since the mRNA-levels provide only a first approximation concerning the amounts of the actual proteins, attempts were made to determine the relative protein concentration for the three receptor types in G-cells. Such an approach is only possible by means of advanced mass spectrometry methodology and requires isolated cells. Therefore, a procedure was established that allowed to selectively isolating antral G-cells from GFP-BAC transgenic mice (mGas-EGFP) in which G-cells can be identified by their cell-specific strong EGFP-fluorescence (Takaishi et al., 2011). A typical section through the gastric antrum of such a transgenic mouse is depicted in Figures 2A,B; G-cells exhibit a bright intrinsic EGFP-fluorescence. Using these transgenic animals, we have developed a protocol for a mild tissue dissociation which allowed to manually isolate EGFP-positive G-cells by means of micropipettes and micromanipulators under microscopic surveillance (described in the Materials and Methods Section). A typical cell suspension from antral tissue is shown in Figure 2C. Since the EGFP-positive G-cells retain their intrinsic fluorescence during the dissociation process they could be easily distinguished from non-labeled cells and selectively picked out of the cell suspension.

Bottom Line: Our previous studies have shown that G-cells express suitable receptor types, most notably the peptone-receptor GPR92 and the amino acid receptors GPRC6A and CaSR; however, their relative importance remained unclear.The results indicate that the relative amount of receptor protein for GPR92 was much higher than for the receptor types GPRC6A and CaSR.These findings support the notion that the peptone-receptor GPR92 may be particularly relevant for sensing partially digested protein products.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiology, University of Hohenheim Stuttgart, Germany.

ABSTRACT
A continuous assessment of ingested food in the gastric lumen is essential for fine-tuning the digestive activities, including the secretion of the regulatory hormones such as gastrin. It has been proposed that G-cells may be able to sense the amount of ingested proteins and adjust the secretion of gastrin accordingly. Our previous studies have shown that G-cells express suitable receptor types, most notably the peptone-receptor GPR92 and the amino acid receptors GPRC6A and CaSR; however, their relative importance remained unclear. To determine the relative quantity of each receptor type, individual G-cells isolated from the transgenic mouse line mGas-EGFP were analyzed by means of a Liquid Chromatography Tandem-Mass Spectrometry (LC-MS/MS) procedure. The results indicate that the relative amount of receptor protein for GPR92 was much higher than for the receptor types GPRC6A and CaSR. These findings support the notion that the peptone-receptor GPR92 may be particularly relevant for sensing partially digested protein products. This view was supported by the finding that a high-protein diet affected the expression level of the peptone-receptor GPR92 in the gastric antrum as well as in the circumvallate papillae.

No MeSH data available.


Related in: MedlinePlus