Quantitative Proteomic Analysis of Mouse Sciatic Nerve Reveals Post-injury Upregulation of ADP-Dependent Glucokinase Promoting Macrophage Phagocytosis

Abstract

Nerve injury induces profound and complex changes at molecular and cellular levels, leading to axonal self-destruction as well as immune and inflammatory responses that may further promote neurodegeneration. To better understand how neural injury changes the proteome within the injured nerve, we set up a mouse model of sciatic nerve injury (SNI) and conducted an unbiased, quantitative proteomic study followed by biochemical assays to confirm some of the changed proteins. Among them, the protein levels of ADP-dependent glucokinase (ADPGK) were significantly increased in the injured sciatic nerve. Further examination indicated that ADPGK was specifically expressed and upregulated in macrophages but not neurons or Schwann cells upon injury. Furthermore, culturing immortalized bone marrow-derived macrophages (iBMDMs) in vitro with the conditioned media from transected axons of mouse dorsal root ganglion (DRG) neurons induced ADPGK upregulation in iBMDMs, suggesting that injured axons could promote ADPGK expression in macrophages non-cell autonomously. Finally, we showed that overexpression of ADPGK per se did not activate macrophages but promoted the phagocytotic activity of lipopolysaccharides (LPS)-treated macrophages. Together, this proteomic analysis reveals interesting changes of many proteins within the injured nerve and our data identify ADPGK as an important in vivo booster of injury-induced macrophage phagocytosis.

Current status and progress of research on the ADP-dependent glucokinase gene

“…In 2021, Kai Zhang et al. ( 26 ) created a mouse model of sciatic nerve injury and conducted proteomics studies, revealing a significant increase in the protein level of ADPGK in the injured sciatic nerve. Further research identified that ADPGK was specifically expressed and up-regulated in macrophages, with injured axons capable of independently promoting the upregulation of ADPGK in macrophages.…”

Discovery of therapeutic targets for spinal cord injury based on molecular mechanisms of axon regeneration after conditioning lesion

“…Injury to the peripheral branches of the DRG activates the axonal regeneration program in the central branches, whereby pre-injury to the peripheral branches is termed a conditioning lesion of the DRG [ 6 ]. Molecular changes in these DRG neurons are induced early in the conditioning lesion, allowing their central axonal branches to grow in a typically hostile and inhibitory environment [ 7 , 8 ]. Previous studies have induced axonal regeneration in the spinal cord by mimicking the conditioning effect of peripheral injury [ 3 , 9 – 11 ].…”