Abstract
Purpose :
In response to injury or disease, Müller (Glial) cells undergo ‘reactive gliosis’, which is accompanied by changes in their morphology, gene expression pattern, de-differentiation and sometimes proliferation. Expression of the intermediate filament protein, glial fibrillary acidic protein (GFAP) is the commonly used marker to follow onset of gliosis in Müller cells. As GFAP filaments do not turn over once formed, we have found that GFAP is not a useful marker to monitor on-going, chronic gliotic changes in retina. To overcome this problem and to avoid over-dependence on a single ‘marker’ to follow gliosis, we have designed and developed a new custom PCR array with twenty gliosis-associated genes that provides a robust and reliable tool to monitor Müller cell gliotic changes in retina.
Methods :
To design the custom PCR array, we used previous transcriptome data from isolated Müller cells as well as published microarray data from retinal degenerations including light-induced damage. To test the custom PCR array, we examined transcript levels of the twenty genes in retinas from wild type mice exposed to strong light to induce photoreceptor degeneration. RNA was extracted from the retinas at different times from 12 hr to 14 days after light damage and transcript levels were determined using the custom PCR array prepared by SABiosciences (Frederick, MD).
Results :
The results showed a strong upregulation of the twenty genes in the degenerating retina. The majority of the genes showed early transcriptional upregulation followed by a decline. The transcript level changes ranged from 2- to 20-fold increase. However, the time course of induction and decline in transcript levels varied among the genes studied. Importantly, the upregulated genes belonged to diverse functional classes that affect cell structure, energy metabolism, intracellular signaling, membrane transporters and pumps in Müller cells, indicating genome-wide changes during gliosis. At 12 hr, the earliest time examined, retinal histology was unchanged and little GFAP immunostaining was seen in Müller cells.
Conclusions :
We describe the establishment of a novel custom PCR array as a tool to assess gliotic changes in Müller cells. The biomarker panel should be of significant interest to investigators in the fields of retinal degeneration and regeneration.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.