Proliferation of Mouse Retinal Müller Cells in Response to Methylnitrosourea-Induced Retinotoxic Stress
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Single intraperitoneal injection of methylnitrosourea (MNU) induces in mice the loss of retinal photoreceptors as a nonlinear dose response (Tronov et al. 2015). DNA repair was the putative mechanism for causing a threshold of DNA alkylation in retina cells. Photoreceptor degeneration can stimulate Müller glial cells to transdifferentiate into photoreceptor-like cells in adult mouse retina treated with MNU (Wan et al., 2008). In this paper, we evaluated Müller cell proliferative response to different doses of MNU and compared the response to DNA damage and repair in suspensions of retinal and Müller cells using a comet assay and BrdU (thymidine analogue) as a marker of proliferation. MNU administration in the dose ≤ 40 mg/kg did not result in the activation of Müller cell proliferation in 3 days after the treatment. By this time point, no DNA damage after this dose was observed. For MNU doses that exceed 50 mg/kg, TUNEL-detected death of retinal photoreceptors increased more than 10-fold in the proliferating pool of Müller cells. DNA breaks (single- and double-strand breaks and AP sites) were observed. The results are discussed within the framework of the concept of misbalance of excision repair that results in formation of cytotoxic intermediates in DNA initiated death of photoreceptors followed by activation of Müller retinal cells.
Keywords:retina Müller cells DNA damage repair methylnitrosourea
This study was supported by Russian Foundation for Basic Research, project no. 16-04-00133 а.
COMPLIANCE WITH ETHICAL STANDARDS
Сonflict of interests. The authors declare that they have no conflict of interest.
Statement on the welfare of animals. The ethical principles and requirements stated in the World Medical Association Declaration of Helsinki: http://www.who.int/bulletin/archives/79%284%29373.pdf) were followed.
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