Title : Lanthionine ketimine ethyl ester induces oligodendrocyte progenitor cell maturation mediated by collapsin response mediator protein 2
Abstract:
Lanthionine ketimine ethyl-ester (LKE) is a synthetic derivative of lanthionine ketimine (LK), a naturally occurring metabolite of the nonproteinogenic amino acid lanthionine. Previously we showed that LKE increases differentiation of oligodendrocyte precursor cells (OPCs) in vitro, reduces clinical scores in the EAE mouse model of multiple sclerosis, and increases remyelination in the Cuprizone chemically-induced model of demyelination. The mechanisms of action of LKE are not fully known, but it has been reported that LKE regulates the activity of collapsin response mediator protein-2 (CRMP2) by blocking its phosphorylation. In the current study we tested if CRMP2 mediates LKE effects using mice with conditional knockout (cKO) from OPCs and in cells with CRMP2 depletion. To generate OPC specific CRMP2 cKO we crossed CRMP2 floxed mice with PDGFRa-CreER mice. To confirm cell specificity, we crossed PDGFRa-CreER mice to TdTomato expressing reporter mice. Following treatment with tamoxifen, the PDGFRa-Cre-ER : TdTomato mice showed expressed Tomato reporter in OPCs, confirmed by colocalization staining with PDGFRa but not with GFAP or Iba1. CRMP2 cKO and wild type (Cre-) littermates were administered CPZ for 3 weeks then analyzed for glial cell activation and myelin loss. The cKO mice showed increased GFAP and Iba1 expression, however myelin expression (MBP and BlackGold staining) was not altered. Acutely isolated OPCs from these mice were treated in vitro with 4-hydroxy tamoxifen to deplete CRMP2, then grown in differentiation media for up to 3 days. In contrast to the wildtype cells, CRMP2 cKO OPCs showed increased differentiation (increased MBP expression) which was not affected by treatment with LKE. These results suggest that LKE acts via inhibition of CRMP2 activity, such that depletion of CRMP2 replicates LKE actions. This work was funded in part by grants from the National MS Society and the Department of Veterans Affairs.
