Abstract
Purpose :
The sigma 2 receptor (σ2R) was recently identified as the endoplasmic reticulum (ER)-resident membrane protein transmembrane protein 97 (TMEM97). To explore the functional roles of σ2R/Tmem97 in retinal cells, we examined the expression of σ2R in the retina.
Methods :
The temporal pattern of σ2R/Tmem97 expression was examined by Western blotting analysis. Retinas were dissected from Sprague-Dawley rats of postnatal day (PD) 10, 15, 20, 30, and 60. Total protein was electrophoresed and the σ2R/Tmem97 protein was detected with anti-TMEM97 antibodies. The spatial pattern of σ2R/Tmem97 expression was investigated by imminocytochemical analysis in retinas of PD 60 rats. Tissue sections displaying the entire retina along the vertical meridian were cut on a cryostat, stained with anti-TMEM97 antibodies to detect σ2R/Tmem97, double-stained with antibodies against glutamine synthetase to identify Müller cells, and examined by confocal microscopy.
Results :
At PD 10 and 15 when the retina is not fully developed, the levels of σ2R/Tmem97 are relatively low. Expression of σ2R/Tmem97 increases significantly as the retina matures, reaching the highest level at PD 60. Positive σ2R/Tmem97 staining is found in the retinal ganglion cells, in cells in the inner nuclear layer, and in photoreceptor outer segments, but not in Müller cells.
Conclusions :
σ2R/Tmem97 protein increases during postnatal development in the retina and at a high level in matured retina. The protein is located in retinal ganglion cells, cells in the inner nuclear layer, in rod photoreceptor outer segments, but not in Müller cells. These results suggest a role of σ2R/Tmem97 in retinal neurons in matured retina.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.