ELAVL1/HuR regulates both endo‐ and exogenous neuroprotection in retinal ganglion cells

Abstract

AbstractPurpose: To evaluate the impact of HuR gene silencing on the ratio of age‐related degeneration of Retinal Ganglion Cells (RGC), which potentially describes the efficiency of endogenous neuroprotection mechanisms, as well as to assess the exogenous neuroprotection capacity of HuR‐ silenced RGC in rat glaucoma model treated with Metallothionein.Methods: Thirty‐five eight‐week‐old male Long Evans rats were divided into two groups: experimental and control. Animals from experimental group received intravitreal injection of AAV‐shRNA‐HuR. Control group received injection of AAV‐shRNA scramble control. Animals from both groups were sacrificed in 3 different time points: 2, 4 and 6 months after injection. Both healthy and treated retinas from each animal were collected and processed as whole mounts for immunostainings and RGC count. For the second trial, animals were divided into groups and transfected with virus particles as described above. To induce chronic glaucoma model, 8 weeks after AAV injection, unilateral episcleral vein cauterization was performed. Half of animals from each group received intravitreal injection of Metallothionein (MT), the other group received PBS injection. During the experiment IOP was monitored. Both healthy and treated retinas from each animal were collected and processed as whole mounts for immunostainings and RGC count.Results: RGC count (per visual field under 20× magnification) was 310 ± 31, 296 ± 25, 189 ± 41 in experimental group and 399 ± 51, 395 ± 49, 390 ± 23 in control respectively for 2, 4 and 6 months after injection (Kaplan‐Mayer trend rank p < 0.0001). Loss of RGC in central retina was 33.7% in animals from shRNA‐MT‐treated glaucoma and 11.4% in shRNA control‐MT‐treated glaucoma (p < 0.05). In peripheral part of the retina the loss was 37.4% in animals from shRNA‐MT‐treated glaucoma and 11.5% in shRNA control‐MT‐treated glaucoma (p < 0.01).Conclusions: Silencing of hur gene enhanced age‐related loss of RGC which translates into impaired endogenous neuroprotection pathways, moreover the absence of HuR critically limits neuroprotective activity of exogenously delivered Metallothionein.