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Glutamic acid decarboxylase 67 expression by a distinct population of mouse vestibular supporting cells.

Tavazzani E, Tritto S, Spaiardi P, Botta L, Manca M, Prigioni I, Masetto S, Russo G - Front Cell Neurosci (2014)

Bottom Line: While no evidence for GAD65 expression was found, GAD67 was detected in a distinct population of peripherally-located supporting cells, but not in hair cells or in centrally-located supporting cells.GABA, on the other hand, was found in all supporting cells.The present result indicate that only a discrete population of supporting cells use GAD67 to synthesize GABA.

View Article: PubMed Central - PubMed

Affiliation: Department of Brain and Behavioral Sciences, University of Pavia Pavia, Italy.

ABSTRACT
The function of the enzyme glutamate decarboxylase (GAD) is to convert glutamate in γ-aminobutyric acid (GABA). Glutamate decarboxylase exists as two major isoforms, termed GAD65 and GAD67, that are usually expressed in GABA-containing neurons in the central nervous system. GAD65 has been proposed to be associated with GABA exocytosis whereas GAD67 with GABA metabolism. In the present immunofluorescence study, we have investigated the presence of the two GAD isoforms in the semicircular canal cristae of wild type and GAD67-GFP knock-in mice. While no evidence for GAD65 expression was found, GAD67 was detected in a distinct population of peripherally-located supporting cells, but not in hair cells or in centrally-located supporting cells. GABA, on the other hand, was found in all supporting cells. The present result indicate that only a discrete population of supporting cells use GAD67 to synthesize GABA. This is the first report of a marker that allows to distinguish two populations of supporting cells in the vestibular epithelium. On the other hand, the lack of GABA and GAD enzymes in hair cells excludes its involvement in afferent transmission.

No MeSH data available.


Related in: MedlinePlus

Lack of GAD65 expression in the mouse crista. (A) Photomicrographs of a crista transverse confocal section showing the expression of GAD67 (green), GAD65 (red), cell nuclei (blue; DAPI), and the merged image. Note the absence of GAD65 immunofluorescence. (B) Photomicrograph of a confocal section of a mouse cerebellum slice taken as positive control for GAD65 antibody labeling (red). Note the weak and diffuse immunofluorescence for GAD65 inside Purkinje cells (arrows) and immunofluorescent spots labeling around Purkinje cells (white arrowhead), in the molecular layer (yellow arrowhead) and in the granular layer (green arrowheads). Dashed lines indicate the bounders among the three layers.
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Figure 7: Lack of GAD65 expression in the mouse crista. (A) Photomicrographs of a crista transverse confocal section showing the expression of GAD67 (green), GAD65 (red), cell nuclei (blue; DAPI), and the merged image. Note the absence of GAD65 immunofluorescence. (B) Photomicrograph of a confocal section of a mouse cerebellum slice taken as positive control for GAD65 antibody labeling (red). Note the weak and diffuse immunofluorescence for GAD65 inside Purkinje cells (arrows) and immunofluorescent spots labeling around Purkinje cells (white arrowhead), in the molecular layer (yellow arrowhead) and in the granular layer (green arrowheads). Dashed lines indicate the bounders among the three layers.

Mentions: A set of immunofluorescence labeling experiments was also performed to assess the expression of GAD65 in the crista sensory epithelium. However, we found no evidence for this isoform expression in either wild type (data not shown) or GAD67-GFP knock-in mice (Figure 7A). The functionality of the GAD65 antibody was previously assessed in the mouse cerebellum (Figure 7B).


Glutamic acid decarboxylase 67 expression by a distinct population of mouse vestibular supporting cells.

Tavazzani E, Tritto S, Spaiardi P, Botta L, Manca M, Prigioni I, Masetto S, Russo G - Front Cell Neurosci (2014)

Lack of GAD65 expression in the mouse crista. (A) Photomicrographs of a crista transverse confocal section showing the expression of GAD67 (green), GAD65 (red), cell nuclei (blue; DAPI), and the merged image. Note the absence of GAD65 immunofluorescence. (B) Photomicrograph of a confocal section of a mouse cerebellum slice taken as positive control for GAD65 antibody labeling (red). Note the weak and diffuse immunofluorescence for GAD65 inside Purkinje cells (arrows) and immunofluorescent spots labeling around Purkinje cells (white arrowhead), in the molecular layer (yellow arrowhead) and in the granular layer (green arrowheads). Dashed lines indicate the bounders among the three layers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269132&req=5

Figure 7: Lack of GAD65 expression in the mouse crista. (A) Photomicrographs of a crista transverse confocal section showing the expression of GAD67 (green), GAD65 (red), cell nuclei (blue; DAPI), and the merged image. Note the absence of GAD65 immunofluorescence. (B) Photomicrograph of a confocal section of a mouse cerebellum slice taken as positive control for GAD65 antibody labeling (red). Note the weak and diffuse immunofluorescence for GAD65 inside Purkinje cells (arrows) and immunofluorescent spots labeling around Purkinje cells (white arrowhead), in the molecular layer (yellow arrowhead) and in the granular layer (green arrowheads). Dashed lines indicate the bounders among the three layers.
Mentions: A set of immunofluorescence labeling experiments was also performed to assess the expression of GAD65 in the crista sensory epithelium. However, we found no evidence for this isoform expression in either wild type (data not shown) or GAD67-GFP knock-in mice (Figure 7A). The functionality of the GAD65 antibody was previously assessed in the mouse cerebellum (Figure 7B).

Bottom Line: While no evidence for GAD65 expression was found, GAD67 was detected in a distinct population of peripherally-located supporting cells, but not in hair cells or in centrally-located supporting cells.GABA, on the other hand, was found in all supporting cells.The present result indicate that only a discrete population of supporting cells use GAD67 to synthesize GABA.

View Article: PubMed Central - PubMed

Affiliation: Department of Brain and Behavioral Sciences, University of Pavia Pavia, Italy.

ABSTRACT
The function of the enzyme glutamate decarboxylase (GAD) is to convert glutamate in γ-aminobutyric acid (GABA). Glutamate decarboxylase exists as two major isoforms, termed GAD65 and GAD67, that are usually expressed in GABA-containing neurons in the central nervous system. GAD65 has been proposed to be associated with GABA exocytosis whereas GAD67 with GABA metabolism. In the present immunofluorescence study, we have investigated the presence of the two GAD isoforms in the semicircular canal cristae of wild type and GAD67-GFP knock-in mice. While no evidence for GAD65 expression was found, GAD67 was detected in a distinct population of peripherally-located supporting cells, but not in hair cells or in centrally-located supporting cells. GABA, on the other hand, was found in all supporting cells. The present result indicate that only a discrete population of supporting cells use GAD67 to synthesize GABA. This is the first report of a marker that allows to distinguish two populations of supporting cells in the vestibular epithelium. On the other hand, the lack of GABA and GAD enzymes in hair cells excludes its involvement in afferent transmission.

No MeSH data available.


Related in: MedlinePlus