title: Activation of PPAR-γ and PTEN cascade participates in lovastatin-mediated accelerated differentiation of oligodendrocyte progenitor cells.
abstract: Previously, we and others documented that statins including-lovastatin (LOV) promote the differentiation of oligodendrocyte progenitor cells (OPCs) and remyelination in experimental autoimmune encephalomyelitis (EAE), an multiple sclerosis (MS) model. Conversely, some recent studies demonstrated that statins negatively influence oligodendrocyte (OL) differentiation in vitro and remyelination in a cuprizone-CNS demyelinating model. Therefore, herein, we first investigated the cause of impaired differentiation of OLs by statins in vitro settings. Our observations indicated that the depletion of cholesterol was detrimental to LOV treated OPCs under cholesterol/serum-deprived culture conditions similar to that were used in conflicting studies. However, the depletion of geranylgeranyl-pp under normal cholesterol homeostasis conditions enhanced the phenotypic commitment and differentiation of LOV-treated OPCs ascribed to inhibition of RhoA-Rho kinase. Interestingly, this effect of LOV was associated with increased activation and expression of both PPAR-γ and PTEN in OPCs as confirmed by various pharmacological and molecular based approaches. Furthermore, PTEN was involved in an inhibition of OPCs proliferation via PI3K-Akt inhibition and induction of cell cycle arrest at G1 phase, but without affecting their cell survival. These effects of LOV on OPCs in vitro were absent in the CNS of normal rats chronically treated with LOV concentrations used in EAE indicating that PPAR-γ induction in normal brain may be tightly regulated-providing evidences that statins are therapeutically safe for humans. Collectively, these data provide initial evidence that statin-mediated activation of the PPAR-γ-PTEN cascade participates in OL differentiation, thus suggesting new therapeutic-interventions for MS or related CNS-demyelinating diseases.
authors.affiliation: Department of Pediatrics, Darby Children's Research Institute, Medical University of South Carolina, South Carolina, USA.
authors.forename: Ajaib S
authors.initials: AS
authors.lastname: Paintlia
authors.forename: Manjeet K
authors.initials: MK
authors.lastname: Paintlia
authors.forename: Avtar K
authors.initials: AK
authors.lastname: Singh
authors.forename: John K
authors.initials: JK
authors.lastname: Orak
authors.forename: Inderjit
authors.initials: I
authors.lastname: Singh
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D018920:Coculture Techniques; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D008148:Lovastatin / Q000494:pharmacology*; D009413:Nerve Fibers, Myelinated / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D009836:Oligodendroglia / Q000187:drug effects* / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000187:drug effects* / Q000378:metabolism
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D018696:Neuroprotective Agents; D047495:PPAR gamma; D008148:Lovastatin; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human