CREB Activation by Mini-Chaperone CPP-P1 Enhances Retinal Ganglion Cell Survival in an Acute Glaucoma Model

dc.creatorJohnson, Gretchenen_US
dc.creatorNagaraj, Ramen_US
dc.creatorStankowska, Dorotaen_US
dc.creator.orcid0000-0001-7330-269X (Johnson, Gretchen)
dc.descriptionResearch Appreciation Day Award Winner - School of Biomedical Sciences, 2024 North Texas Eye Research Institute Graduate Student Award - 1st Placeen_US
dc.description.abstractPurpose: Alpha-B crystallin is a heat shock protein that has been found to have anti-apoptotic properties and was used to design the novel mini-chaperone called peptain-1 (P1) conjugated with a cell-penetrating peptide (CPP), named CPP-P1. Transcriptomics of primary retinal ganglion cells (RGCs) isolated from adult rats subjected to ocular hypertension and treated with CPP-P1 revealed the activation of CREB signaling as a major pathway activated by the drug. Creb activation by phosphorylation (p-Creb) was previously confirmed in primary RGCs and tested here in a rat model of ocular hypertension. Methods: Adult male Brown Norway rats (N=15, 5 per group) were grouped into naïve, IOP-Vehicle, and IOP-CPP-P1 experimental groups. Silicone oil (20µl) was injected into the anterior chamber, and 2µl of either PBS (vehicle) or CPP-P1 (2µg/µl) was injected intravitreally. On day 7 of elevated IOP, rats were euthanized. Retinal sections obtained were stained with Creb, p-Creb, and DAPI and imaged at 4X for cell counts and at 20X for integrated density measurements. Unpaired t-tests or Mann-Whitney tests in GraphPad Prism were used to calculate statistical significance. Retinal punches from post-mortem human eyes (N=3) were cultured with PBS or CPP-P1 (12.5µg/ml) for 48 hours, and tissue RNA was collected for qPCR. Results: Ganglion cell layer counts obtained from rat retinal sections showed that the silicone oil injury group with no intervention (IOP-Veh) had a 51% decrease in ganglion cells compared to the naïve group (p<0.0001), and the silicone injury with CPP-P1 intervention group (IOP-CPP-P1) showed only a 23% decrease compared to the naïve group (p=0.0016). Integrated density measurements of Creb expression in IOP-Veh was 17% (p=0.615) higher than the naïve group, while in IOP-CPP-P1, it was 136% (p=0.092) higher than the naïve group. Expression of p-Creb showed a decrease in IOP-Veh by 50% (p=0.056) in comparison to the naïve group, while the IOP-CPP-P1 group was significantly higher than the IOP-Veh group (p=0.036). RNA expression of Creb1 in human retinal tissue was increased by 1.7-fold with CPP-P1 treatment. Discussion: IOP-mediated RGC damage was mitigated by CPP-P1 treatment, demonstrating neuroprotective effects when compared to vehicle-treated rats. CREB signaling contributes to CPP-P1-mediated neuroprotection during glaucomatous insults.en_US
dc.description.sponsorshipGates Grubstake Award and R01EY029823en_US
dc.titleCREB Activation by Mini-Chaperone CPP-P1 Enhances Retinal Ganglion Cell Survival in an Acute Glaucoma Modelen_US