Single-nucleus transcriptome profiling of prefrontal cortex induced by chronic methamphetamine treatment

Background Methamphetamine(METH)addiction causes a huge burden on society.The prefrontal cortex(PFC),associated with emotion and cognitive behaviours,is also involved in addiction neurocircuitry.Although bulk RNA sequencing has shown METH-induced gene alterations in the mouse PFC,the impact on different cell types remains unknown.Aims To clarify the effects of METH treatment on different cell types of the PFC and the potential pathways involved in METH-related disorders.Methods We performed single-nucleus RNA sequencing(snRNA-seq)to examine the transcriptomes of 20465 nuclei isolated from the PFC of chronic METH-treated and control mice.Main cell types and differentially expressed genes(DEGs)were identified and confirmed by RNA fluorescence in situ hybridization(FISH).Results Six main cell types were identified depending on the single-cell nucleus sequencing;of particular interest were the mature oligodendrocytes in the PFC.The DEGs of mature oligodendrocytes were enriched in the myelin sheath,adenosine triphosphate(ATP)metabolic process,mitochondrial function and components,and so on.The messenger RNA levels of Aldoc and Atp5l(FISH)and the protein level of the mitochondrial membrane pore subunit TOM40(immunofluorescence)decreased in the mature oligodendrocytes.Fast blue staining and transmission electron microscopy image indicated myelin damage,and the myelin thickness decreased in METH brains.Conclusions snRNA-seq reveals altered transcriptomes of different cell types in mouse PFC induced by chronic METH treatment,underscoring potential relationships with psychiatric disorders.

Mechanisms of the spatial memory deficits induced by injection of okadaic acid into the Meynert nucleus basalis of rats

We previously reported that the injection of okadaic acid(OA)into theMeynert nucleus basalis of rats induced spatial memory deficits.The present study was designed to further explore the underlying mechanisms.We found that the level of acetylcholine(Ach)in the hippocampus significantly decreased 24 h after injection of OA into the Meynert nucleus basalis of rats.Simultaneously,spatial memory deficit,PP-2A inhibition and tau hyperphosphorylation at Ser-198/Ser-199/Ser-202(Tau-1 epitope)and Ser-396/Ser-404(PHF-1 epitope)were observed.With the restoration of hippocampus Ach to normal levels at 48 and 72 h after the injection,the spatial memory deficits,PP-2A inhibition and tau hyperphosphorylation were reversed.It is suggested that injection of OA into the Meynert nucleus basalis of rats may impair the hippocampus-dependent spatial memory through damaging the cholinergic projection between the Meynert nucleus basalis and the hippocampus and the selective inhibition of PP-2A and tau hyperphosphorylation may be at least part of the underlying mechanisms.

Effect of inhibiting tyrosine kinase Src expression on protein phosphatase 2A and tau phosphorylation

The aim of this study is to investigate the effect of tyrosine kinase Src on Tyrosine 307(Y307)phosphor-ylation,protein phosphatase 2A(PP2A)activity,and on tau phosphorylation.Specific Src siRNA was transfected into cultured mouse neuroblastoma N2a cells to inhibit the expression of Src protein,and the phosphorylation levels of PP2A Y307 and tau at different sites,as well as PP2A activity were detected at different time points after siRNA transfection.Twelve hours after siRNA transfec-tion,the protein level of Src was dramatically decreased,with decreased PP2A Y307 phosphorylation.However,the total PP2A protein level was also decreased,together with a decreased PP2A activity.Tau was hyperpho-sphorylated at the Ser198/199/202 sites.Multiple factors may be involved in the cellular regulation of PP2A activ-ity.Inhibiting Src expression could induce inactivation of PP2A and tau hyperphosphorylation.