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Heather Kayew Mak, Xu Cao, Jasmine Sum Yee Yung, Heidi Ng, Tin Lap Lee, Christopher Kai-Shun Leung; MicroRNA-19a enhances axon regeneration in retinal ganglion cells. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2600.
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© ARVO (1962-2015); The Authors (2016-present)
Retinal ganglion cells (RGCs) lose capacity to regenerate axons in early postnatal age. While a number of transcription factors and signaling molecules have been implicated to the loss of regenerative potential of RGC axon, their upstream regulators are largely unstudied. We investigated the association between developmental decline of RGC regenerative potential and age-related changes in microRNA (miRNA) expression and demonstrated that miRNA-19a augments RGC axon regenerative capacity after optic nerve (ON) injury.
Microarray was performed on purified RGCs from Sprague Dawley (SD) rats at embryonic day 21 (E21), postnatal day 6 (P6), postnatal day 14 (P14), and postnatal day 30 (P30) to study the changes in miRNA expression. Age-related change in miRNA expression was confirmed by RT-PCR. RGC axon length and growth rate from SD rats and human adult donor eyes were measured by microfluidic chambers (MFCs) and time-lapse imaging, respectively, after transduction of AAV-miR-19a-eGFP or control. C57BL/6 mice were intravitreally injected with AAV-miR-19a-eGFP or control 2 weeks before ON crush and the number of regenerating axons was measured 4 weeks after crush.
Microarray revealed 65 miRNAs to be significantly downregulated from E21 to P30 in which RT-PCR confirmed that miR-19a decreased 55-fold from E21 to P30 (p<0.001). miR-19a increased RGC axon length in MFCs by 2.62- and 2.01-fold on 14 and 21 days in vitro, respectively (p<0.006), and accelerated axon regenerative growth rate by 2.46-fold (p<0.001) in time-lapse imaging compared with controls. Human adult RGCs with miR-19a had longer axon and total neurite lengths by 26.7% (p=0.025) and 59.8% (p<0.001), respectively, compared with controls. Mice with miR-19a had 2-folds more regenerated axons (p=0.004) at every 0.5 mm starting 1 mm from the ON crush site.
There is an age-related change of miRNA levels in RGCs, which coincides with the age-related decline in axon growth potential. We showed that the loss of axon regenerative potential can be partially restored by upregulating miR-19a in RGCs in vitro and in vivo, presenting a new potential therapeutic approach to resuscitate age-related loss of axon growth ability.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Heirarchical cluster of E21, P6, P14, and P30 RGC miRNA and 65 miRNAs significantly downregulated from E21 to P30.
ON sections after crush with AAV-miR-19a-eGFP (top) or AAV-eGFP (bottom), and estimated number of regenerated axons.
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