MicroRNA and mRNA profiling of cerebral cortex in a transgenic mouse model of Alzheimer’s disease by RNA sequencing

In a previous study,we found that long non-coding genes in Alzheimer’s disease(AD)are a result of endogenous gene disorders caused by the recruitment of microRNA(miRNA)and mRNA,and that miR-200a-3p and other representative miRNAs can mediate cognitive impairment and thus serve as new biomarkers for AD.In this study,we investigated the abnormal expression of miRNA and mRNA and the pathogenesis of AD at the epigenetic level.To this aim,we performed RNA sequencing and an integrative analysis of the cerebral cortex of the widely used amyloid precursor protein and presenilin-1 double transgenic mouse model of AD.Overall,129 mRNAs and 68 miRNAs were aberrantly expressed.Among these,eight down-regulated miRNAs and seven up-regulated miRNAs appeared as promising noninvasive biomarkers and therapeutic targets.The main enriched signaling pathways involved mitogen-activated kinase protein,phosphatidylinositol 3-kinase-protein kinase B,mechanistic target of rapamycin kinase,forkhead box O,and autophagy.An miRNA-mRNA network between dysregulated miRNAs and corresponding target genes connected with AD progression was also constructed.These miRNAs and mRNAs are potential biomarkers and therapeutic targets for new treatment strategies,early diagnosis,and prevention of AD.The present results provide a novel perspective on the role of miRNAs and mRNAs in AD.This study was approved by the Experimental Animal Care and Use Committee of Institute of Medicinal Biotechnology of Beijing,China(approval No.IMB-201909-D6)on September 6,2019.

Implication of a novel truncating mutation in titin as a cause of autosomal dominant left ventricular noncompaction

BACKGROUND Mutation in the titin gene(TTN)in left ventricular noncompaction(LVNC)has been reported with a highly heterogeneous prevalence,and the molecular mechanisms underlying the pathogenesis of TTN gene mutation are uncharacteri-zed.In the present study,we identified a novel TTN mutation in a pedigree with LVNC and investigated the potential pathogenic mechanism by functional studies.METHODS The whole-genome sequencing with linkage analysis was performed in a 3-generation family affected by autoso-mal dominant LVNC cardiomyopathy.The clustered regularly interspaced short palindromic repeats associated protein 9(CRISPR/Cas9)technology was used to establish novel truncating mutation in TTN in a rat cardiomyoblast H9C2 cell line in vitro,in which functional studies were carried out and characterized in comparison to its wild-type counterpart.RESULTS A novel truncating mutation TTN p.R2021X was identified as the only plausible disease-causing variant that segreg-ated with disease among the five surviving affected individuals,with an interrogation of the entire genome excluding other po-tential causes.Quantitative reverse transcription-polymerase chain reaction and cellular immunofluorescence supported a haplo-insufficient disease mechanism in titin truncation mutation cardiomyocytes.Further functional studies suggested mitochondrial abnormities in the presence of mutation,including decreased oxygen consumption rate,reduced adenosine triphosphate produc-tion,impaired activity of electron translation chain,and abnormal mitochondrial structure on electron microscopy.Impaired aut-ophagy under electron microscopy accompanied with activation of the Akt-mTORC1 signaling pathway was observed in TTN p.R2021X truncation mutation cardiomyocytes.CONCLUSIONS The TTN p.R2021X mutation has a function in the cause of a highly penetrant familial LVNC.These findings expand the spectrum of titin’s roles in cardiomyopathies and provide novel insight into the molecular basis of titin-truncating variants-associated LVNC.