Axon regeneration after optic nerve injury in rats can be improved via PirB knockdown in the retina

Abstract

Background In the central nervous system (CNS), three types of myelin-associated inhibitors (MAIs) exert major inhibitory effects on nerve regeneration: Nogo-A, myelin-associated glycoprotein (MAG), and oligodendrocyte-myelin glycoprotein (OMgp). MAIs have two co-receptors, Nogo receptor (NgR) and paired immunoglobulin-like receptor B (PirB). Existing studies confirm that inhibiting NgR only exerted a modest disinhibitory effect in CNS. However, the inhibitory effects of PirB on nerve regeneration after binding to MAIs are controversial too. We aimed to further investigate the effect of PirB knockdown on the neuroprotection and axonal regeneration of retinal ganglion cells (RGCs) after optic nerve injury in rats. Methods The differential expression of PirB in the retina was observed via immunofluorescence and western blotting after 1, 3, and 7 days of optic nerve injury (ONI). The retina was locally transfected with adeno-associated virus (AAV) PirB shRNA, then, the distribution of virus in tissues and cells was observed 21 days after AAV transfection to confirm the efficiency of PirB knockdown. Level of P-Stat3 and expressions of ciliary neurotrophic factor (CNTF) were detected via western blotting. RGCs were directly labeled with cholera toxin subunit B (CTB). The new axons of the optic nerve were specifically labeled with growth associated protein-43 (GAP43) via immunofluorescence. Flash visual evoked potential (FVEP) was used to detect the P1 and N1 latency, as well as N1-P1, P1-N2 amplitude to confirm visual function. Results PirB expression in the retina was significantly increased after ONI. PirB knockdown was successful and significantly promoted P-Stat3 level and CNTF expression in the retina. PirB knockdown promoted the regeneration of optic nerve axons and improved the visual function indexes such as N1-P1 and P1-N2 amplitude. Conclusions PirB is one of the key molecules that inhibit the regeneration of the optic nerve, and inhibition of PirB has an excellent effect on promoting nerve regeneration, which allows the use of PirB as a target molecule to promote functional recovery after ONI.

The factors affecting neurogenesis after stroke and the role of acupuncture

“…It has been shown that POSH formed an inhibitory complex by binding to F-actin-binding protein (Shroom3), which activated the POSH/Shroom3/ROCK signaling pathway, leading to a decrease in Myosin II expression and inhibition of axonal growth (111,112). The study confirmed that the knockdown of Pir B caused more axon regeneration than the knockdown of NgR1, suggesting that Pir B plays a more important role in myelin inhibition (113). By antagonizing the action of Nogo-A and Pir B, it could inhibit POSH expression and suppress the activity of downstream molecules Shroom3/ROCK/Rho A, which effectively reverses the inhibition of its axonal growth (111,114,115).…”

The cAMP Response Element- Binding Protein/Brain-Derived Neurotrophic Factor Pathway in Anterior Cingulate Cortex Regulates Neuropathic Pain and Anxiodepression Like Behaviors in Rats

“…To demonstrate the role of the ACC in neuropathic pain and comorbidity, we first wanted to verify the anatomical connection between the ACC and the spinal cord. Cholera toxin subunit B (CTB), taken up by axon terminals and retrogradely transported to the soma, is currently the most widely used retrograde tracer ( Yang M. et al, 2021 ). We microinjected CTB-555(250 nl, green) into the contralateral ACC and CTB-488(250 nl, red) into the ipsilateral spinal dorsal horn ( Figure 2A ).…”

Purified neuronal populations of regenerating retinal ganglion cells reveal DNA methylation-mediated role of Na+/K+-ATPase in axon regeneration

“…72,73 However, even using this genome-wide loss-of-function methodology and other recently developed technologies such as single-cell RNA sequencing and transcription factor screens, researchers have not speci cally isolated regenerated cells from nonregenerated cells. [73][74][75] Unique genes and processes are involved in adult RGC axon regeneration Few studies have thoroughly investigated the role of DNA methylation in axon regeneration, particularly in relation to neuronal growth competence. 19,33,36,46,76 Recent studies have focused on transcriptional alterations associated with neuronal injury.…”