(OR15-04-26) Subcellular Localization of STRA6

Objectives: Psoriasis is an inflammatory skin condition that affects 3% of adults in the United States and greatly reduces quality of life. It is treated with narrowband ultraviolet B (UVB) irradiation and/or oral retinoids. The purpose of this study was to examine the effects of UVB on the vitamin A receptor Stimulated by Retinoic Acid 6 (STRA6). The hypothesis is that the localization and expression patterns of STRA6 changes in response to ultraviolet B irradiation.

Methods: Seven-week-old C57BL/6 mice fed an AIN93G diet were wax striped. Five days later, they were either exposed or not to UVB and skin collected 48 hours later. Co-Immunofluorescence was performed with antibodies against STRA6 and ATP5A1 to determine if STRA6 localized to the mitochondria. Microscopy was performed using a Zeiss LSM900 confocal microscope using a 63x oil objective. Multiple pictures (z-stacks) were collected from each tissue sample and analyzed using ImageJ and Zen Blue v3.9. Pearson’s and Mander’s (M1 and M2) correlation coefficients were calculated using GraphPad and groups compared by Student t-test.

Results: There was a moderate colocalization (ranging from 0.4 to 0.7) between STRA6 and ATP5A1 in all mice examined. In male mice, exposure to UVB increased the M1 coefficient but not M2 (p < 0.05), suggesting that mitochondria may be more strongly colocalized with STRA6 than the converse (STRA6 more strongly colocalized with mitochondria). There were no significant differences in the colocalization between ATP5A1 and STRA6 in male and female mice or between UVB-treated and untreated mice using the Pearson’s correlations. The mean fluorescence intensity of STRA6 was also significantly higher in female mice treated with UVB versus non-treated female mice (p < 0.05).

Conclusions: The vitamin A receptor STRA6 localized to the mitochondria in epidermal skin. UVB increased this colocalization when looking at Mander’s but not Pearson’s correlations in males and increased the intensity of STRA6 in female. Future studies will be performed to explore the association with UVB, ATP5A1, and STRA6, as well as examining the subcellular colocalization of STRA6 with other organelles in the cell.

Funding Sources: This project was supported by various student and faculty internal grants.