Presenilin mutations and their impact on neuronal differentiation in Alzheimer’s disease

The presenilin genes(PSEN1 and PSEN2)are mainly responsible for causing early-onset familial Alzheimer’s disease,harboring~300 causative mutations,and representing~90%of all mutations associated with a very aggressive disease form.Presenilin 1 is the catalytic core of theγ-secretase complex that conducts the intramembranous proteolytic excision of multiple transmembrane proteins like the amyloid precursor protein,Notch-1,N-and E-cadherin,LRP,Syndecan,Delta,Jagged,CD44,ErbB4,and Nectin1a.Presenilin 1 plays an essential role in neural progenitor maintenance,neurogenesis,neurite outgrowth,synaptic function,neuronal function,myelination,and plasticity.Therefore,an imbalance caused by mutations in presenilin 1/γ-secretase might cause aberrant signaling,synaptic dysfunction,memory impairment,and increased Aβ42/Aβ40 ratio,contributing to neurodegeneration during the initial stages of Alzheimer’s disease pathogenesis.This review focuses on the neuronal differentiation dysregulation mediated by PSEN1 mutations in Alzheimer’s disease.Furthermore,we emphasize the importance of Alzheimer’s disease-induced pluripotent stem cells models in analyzing PSEN1 mutations implication over the early stages of the Alzheimer’s disease pathogenesis throughout neuronal differentiation impairment.

Genetic profiles of familial late-onset Alzheimer’s disease in China:The Shanghai FLOAD study

Compared with early-onset familial AD(FAD),the heritability of most familial lateonset Alzheimer’s disease(FLOAD)cases still remains unclear.However,there are few reported genetic profiles of FLOAD to date.In the present study,targeted sequencing of selected candidate genes was conducted for each of 90 probands with FLOAD and 101 unrelated matched normal controls among Chinese Han population.Results show a significantly lower rate of mutation in APP and PSENs,and APOE e4 genetic risk is higher for FLOAD.Among the Chinese FLOAD population,the most frequent variant was CR1 rs116806486[5.6%,95%CI(1.8%,12.5%)],followed by coding variants of TREM2(4.4%,95%CI(1.2%,10.9%))and novel mutations of ACE[3.3%,95%CI(0.7%,9.4%)].Next,we found that novel pathogenic mutations in ACE including frame-shift and nonsense mutations were in association with FLOAD regardless of APOE e4 status.Evidence from the Alzheimer’s disease Neuroimaging Initiative(ADNI)database also supported this finding in different ethnicities.Results of in vitro analysis suggest that frame-shift and nonsense mutations in ACE may be involved in LOAD through decreased ACE protein levels without affecting direct processing of APP.