Affiliations: [a] Institute of Experimental Ophthalmology and DFG-Excellence Center, Cells in Motion (CiM, area C.4), School of Medicine, University of Münster, Münster, Germany
| [b] Department of Ophthalmology, Laboratory of Experimental Ophthalmology, University Clinic Duesseldorf, Duesseldorf, Germany
| [c] Institute of Regenerative Medicine (CeRA) and DFG-Excellence Center, Cells in Motion (CiM, area A.2), School of Medicine, University of Münster, Münster, Germany
Correspondence:
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Corresponding author: Sonja Mertsch, Laboratory of Experimental Ophthalmology, Department of Ophthalmology, University Clinic Duesseldorf, Moorenstraße 5, 40225 Duesseldorf, Germany. Tel.: +49 211 385428163; Fax: +49 211 385428164; E-mail: Sonja.Mertsch@med.uni-duesseldorf.de.
Note: [1] No animal had to die for the purpose of these experiments. All data were obtained from animal corpses.
Abstract: Background:Retinal ganglion cells (RGCs) of mammals lose the ability to regenerate injured axons during postnatal maturation, but little is known about the underlying molecular mechanisms. Objective:It remains of particular importance to understand the mechanisms of axonal regeneration to develop new therapeutic approaches for nerve injuries. Methods:Retinas from newborn to adult monkeys (Callithrix jacchus)1 were obtained immediately after death and cultured in vitro. Growths of axons were monitored using microscopy and time-lapse video cinematography. Immunohistochemistry, Western blotting, qRT-PCR, and genomics were performed to characterize molecules associated with axonal regeneration and growth. A genomic screen was performed by using retinal explants versus native and non-regenerative explants obtained from eye cadavers on the day of birth, and hybridizing the mRNA with cross-reacting cDNA on conventional human microarrays. Followed the genomic screen, siRNA experiments were conducted to identify the functional involvement of identified candidates. Results:Neuron-specific human ribonucleoprotein N (snRPN) was found to be a potential regulator of impaired axonal regeneration during neuronal maturation in these animals. In particular, up-regulation of snRPN was observed during retinal maturation, coinciding with a decline in regenerative ability. Axon regeneration was reactivated in snRPN-knockout retinal ex vivo explants of adult monkey. Conclusion:These results suggest that coordinated snRPN-driven activities within the neuron-specific ribonucleoprotein complex regulate the regenerative ability of RGCs in primates, thereby highlighting a potential new role for snRPN within neurons and the possibility of novel postinjury therapies.
