Ghrelin alleviates 6-hydroxydopamine-induced neurotoxicity in SH-SY5Y cells

Ghrelin is a neuropeptide that has various physiological functions and has been demonstrated to be neuroprotective in a number of neurological disease models.However,the underlying mechanisms of ghrelin in Parkinson’s disease remain largely unexplored.The current study aimed to study the effects of ghrelin in a 6-hydroxydopamine(6-OHDA)-induced Parkinson’s disease model and evaluate the potential underlying mechanisms.In the present study,we treated an SH-SY5 Y cell model with 6-OHDA,and observed that pretreatment with different concentrations of ghrelin(1,10,and 100 nM)for 30 minutes relieved the neurotoxic effects of 6-OHDA,as revealed by Cell Counting Kit-8 and Annexin V/propidium iodide(PI)apoptosis assays.Reverse transcription quantitative polymerase chain reaction and western blot assay results demonstrated that 6-OHDA treatment upregulatedα-synuclein and lincRNA-p21 and downregulated TG-interacting factor 1(TGIF1),which was predicted as a potential transcription regulator of the gene encodingα-synuclein(SNCA).Ghrelin pretreatment was able to reverse the trends caused by 6-OHDA.The Annexin V/PI apoptosis assay results revealed that inhibiting eitherα-synuclein or lincRNA-p21 expression with small interfering RNA(siRNA)relieved 6-OHDA-induced cell apoptosis.Furthermore,inhibiting lincRNA-p21 also partially upregulated TGIF1.By retrieving information from a bioinformatics database and performing both double luciferase and RNA immunoprecipitation assays,we found that lincRNA-p21 and TGIF1 were able to form a double-stranded RNA-binding protein Staufen homolog 1(STAU1)binding site and further activate the STAU1-mediated mRNA decay pathway.In addition,TGIF1 was able to transcriptionally regulateα-synuclein expression by binding to the promoter of SNCA.The Annexin V/PI apoptosis assay results showed that either knockdown of TGIF1 or overexpression of lincRNA-p21 notably abolished the neuroprotective effects of ghrelin against 6-OHDA-induced neurotoxicity.Collectively,these findings suggest that ghrelin exerts neuroprotective effects against 6-OHDA-induced neurotoxicity via the lincRNA-p21/TGIF1/α-synuclein pathway.

Senktide blocks aberrant RTN3 interactome to retard memory decline and tau pathology in social isolated Alzheimer’s disease mice

Sporadic or late-onset Alzheimer’s disease(LOAD)accounts for more than 95%of Alzheimer’s disease(AD)cases without any family history.Although genome-wide association studies have identified associated risk genes and loci for LOAD,numerous studies suggest that many adverse environmental factors,such as social isolation,are associated with an increased risk of dementia.However,the underlying mechanisms of social isolation in AD progression remain elusive.In the current study,we found that 7 days of social isolation could trigger pattern separation impairments and presynaptic abnormalities of the mossy fibre-CA3 circuit in AD mice.We also revealed that social isolation disrupted histone acetylation and resulted in the downregulation of 2 dentate gyrus(DG)-enriched miRNAs,which simultaneously target reticulon 3(RTN3),an endoplasmic reticulum protein that aggregates in presynaptic regions to disturb the formation of functional mossy fibre boutons(MFBs)by recruiting multiple mitochondrial and vesicle-related proteins.Interestingly,the aggregation of RTN3 also recruits the PP2A B subunits to suppress PP2A activity and induce tau hyperphosphorylation,which,in turn,further elevates RTN3 and forms a vicious cycle.Finally,using an artificial intelligence-assisted molecular docking approach,we determined that senktide,a selective agonist of neurokinin3 receptors(NK3R),could reduce the binding of RTN3 with its partners.Moreover,application of senktide in vivo effectively restored DG circuit disorders in socially isolated AD mice.Taken together,our findings not only demonstrate the epigenetic regulatory mechanism underlying mossy fibre synaptic disorders orchestrated by social isolation and tau pathology but also reveal a novel potential therapeutic strategy for AD.