Kriukov, E. | bioRxiv Science

bioRxiv2023

Suppressing DNMT3a Alleviates the Intrinsic Epigenetic Barrier for Optic Nerve Regeneration and Restores Vision in Adult Mice

The limited regenerative potential of the optic nerve in adult mammals presents a major challenge for restoring vision after optic nerve trauma or disease. The mechanisms of this regenerative failure are not fully understood1,2. Here, through small-molecule and genetic screening for epigenetic modulators3, we identify DNA methyltransferase 3a (DNMT3a) as a potent inhibitor of axon regeneration in mouse and human retinal explants. Selective suppression of DNMT3a in retinal ganglion cells (RGCs) by gene targeting or delivery of shRNA leads to robust, full-length regeneration of RGC axons through the optic nerve and restoration of vision in adult mice after nerve crush injury. Genome-wide bisulfite and transcriptome profiling in combination with single nucleus RNA-sequencing of RGCs revealed selective DNA demethylation and reactivation of genetic programs supporting neuronal survival and axonal growth/regeneration by DNMT3a deficiency. This was accompanied by the suppression of gene networks associated with apoptosis and inflammation. Our results identify DNMT3a as the central orchestrator of an RGC-intrinsic mechanism that limits optic nerve regeneration. Suppressing DNMT3a expression in RGCs unlocks the epigenetic switch for optic nerve regeneration and presents a promising therapeutic avenue for effectively reversing vision loss resulted from optic nerve trauma or diseases.

neuroscience↗

bioRxiv2022

Introduced chemokine gradients guide transplanted and regenerated retinal neurons toward their natural position in the retina

Ongoing cell replacement studies and clinical trials have demonstrated the need to control donor and newborn cell behavior within their target tissue. Here we present a methodology to guide stem cell-derived and endogenously regenerated neurons by engineering the microenvironment. Being an "approachable part of the brain," the eye provides a unique opportunity to study donor neuron fate, migration, and integration within the central nervous system. Glaucoma and other optic neuropathies lead to the permanent loss of retinal ganglion cells (RGCs) - the neurons in the retina that transfer all visual information from the eye to the brain. Cell transplantation and transdifferentiation strategies have been proposed to restore RGCs, and one of the significant barriers to successful RGC integration into the existing retinal circuitry is cell migration towards their natural position in the retina. Here we describe a framework for identifying, selecting, and applying chemokines to direct cell migration in vivo within the retina. We have performed an in silico analysis of the single-cell transcriptome of the developing human retina and identified six receptor-ligand candidates to guide stem cell-derived or newborn neurons. The lead candidates were then tested in functional in vitro assays for their ability to guide stem cell-derived RGCs. For the in vivo studies, donor and newborn neurons were differentiated in human and mouse retinal organoids or endogenously reprogrammed with proneuronal transcription factors, respectively. An exogenous stromal cell-derived factor-1 (SDF1) gradient led to a 2.7-fold increase in donor RGC migration into the ganglion cell layer and a 3.3-fold increase in the displacement of newborn RGCs out of the inner nuclear layer. Furthermore, by altering the migratory profile of donor RGCs toward multipolar migration, overall migration was improved in mature retinal tissues. Together, these results highlight the ability and importance of engineering the tissue microenvironment and the individual cells for research and clinical applications in gene and cell therapies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/510158v1_ufig1.gif" ALT="Figure 1"> View larger version (62K): org.highwire.dtl.DTLVardef@1856140org.highwire.dtl.DTLVardef@1b3ca26org.highwire.dtl.DTLVardef@9c9b34org.highwire.dtl.DTLVardef@19187c0_HPS_FORMAT_FIGEXP M_FIG C_FIG In brief, the "in silico - in vitro - in vivo" funnel holds significant potential for identifying targets to control cellular processes in research and clinical applications. In this report, Soucy et al. describes a framework for identifying, selecting, and applying chemokines to direct retinal ganglion cell migration in vivo within the adult mouse retina.

bioengineering↗