Anp32a Promotes Neuronal Regeneration after Spinal Cord Injury of Zebrafish Embryos

After spinal cord injury (SCI) in mammals, neuronal regeneration is limited; in contrast, such regeneration occurs quickly in zebrafish. Member A of the acidic nuclear phosphoprotein 32 (Anp32a) family is involved in neuronal development, but its function is controversial, and its involvement in zebrafish SCI remains unknown. To determine the role of zebrafish Anp32a in the neuronal regeneration of SCI embryos, we microinjected Anp32a mRNA into embryos from zebrafish transgenic line Tg(mnx1:GFP) prior to SCI. Compared to control SCI embryos, the results showed that the regeneration of spinal cord and resumption of swimming capability were promoted by the overexpression of Anp32a mRNA but reduced by its knockdown. We next combined fluorescence-activated cell sorting with immunochemical staining of anti-GFAP and immunofluorescence staining against anti-PH3 on Tg(gfap:GFP) SCI embryos. The results showed that Anp32a promoted the proliferation and cell number of radial glial cells at the injury epicenter at 24 h post-injury (hpi). Moreover, when we applied BrdU labeling to SCI embryos derived from crossing the Tg(gfap:GFP) and Tg(mnx1:TagRFP) lines, we found that both radial glial cells and motor neurons had proliferated, along with their increased cell numbers in Anp32a-overexpression SCI-embryos. On this basis, we conclude that Anp32a plays a positive role in the regeneration of zebrafish SCI embryos.