MicroRNA-19a-PTEN axis is involved in the developmental decline of axon regenerative capacity in retinal ganglion cells

Abstract Irreversible blindness from glaucoma and optic neuropathies is attributed to retinal ganglion cells (RGCs) losing the ability to regenerate axons. While several transcription factors and proteins have demonstrated enhancement of axon regeneration after optic nerve injury, mechanisms contributing to the age-related decline in axon regenerative capacity remain elusive. Here, we show that microRNAs are differentially expressed during RGC development, and identify microRNA-19a (miR-19a) as a heterochronic marker; developmental decline of miR-19a relieves suppression of PTEN, a key regulator of axon regeneration, and serves as a temporal indicator of decreasing axon regenerative capacity. Intravitreal injection of miR-19a promotes axon regeneration after optic nerve crush in adult mice, and increases axon extension in RGCs isolated from aged human donors. This study uncovers a previously unrecognized involvement of the miR-19a-PTEN axis in RGC axon regeneration, and demonstrates therapeutic potential of microRNA-mediated restoration of axon regenerative capacity via intravitreal injection in patients with optic neuropathies.