Diagnostic value of urine formaldehyde in Alzheimer's disease and its influential factors / 中华行为医学与脑科学杂志

Objective To explore the value of urine formaldehyde test in the diagnosis of Alzheimer's disease (AD),and the influential factors of urine formaldehyde level in AD patients.Methods A total of 52 AD patients and 53 cognitively normal controls were recruited in a cohort study.All subjects were no less than 65 years old,and those with acute infection,or dysfunction in heart,liver or kidneys were excluded.The impact of age,gender,onset age,MMSE score,NPI score,MTA score,and ApoE ε4 gene on urine formaldehyde of AD patients were analyzed by multiple regression analysis.Results Urine formaldehyde level of AD group was statistically higher than that of cognitively normal control group ((13.27±4.16)μmol/L vs (10.76±4.47)μmol/L,t=2.99,P=0.15).Urine formaldehyde of AD patients was statistically negatively correlated with MMSE score (β=-0.35,P=0.03) and MTA score (β=-0.38,P=0.02).The impact of onset age,neuropsychiatric disorders and ApoE ε4 gene on urine formaldehyde of AD patients was not statistically significant(all P>0.05).Conclusion Urine formaldehyde level is worthwhile to be explored as a marker in AD diagnosis and severity assessment.

DSSylation, a novel protein modification targets proteins induced by oxidative stress, and facilitates their degradation in cells

Timely removal of oxidatively damaged proteins is critical for cells exposed to oxidative stresses; however, cellular mechanism for clearing oxidized proteins is not clear. Our study reveals a novel type of protein modification that may play a role in targeting oxidized proteins and remove them. In this process, DSS1 (deleted in split hand/split foot 1), an evolutionally conserved small protein, is conjugated to proteins induced by oxidative stresses in vitro and in vivo, implying oxidized proteins are DSS1 clients. A subsequent ubiquitination targeting DSS1-protein adducts has been observed, suggesting the client proteins are degraded through the ubiquitin-proteasome pathway. The DSS1 attachment to its clients is evidenced to be an enzymatic process modulated by an unidentified ATPase. We name this novel protein modification as DSSylation, in which DSS1 plays as a modifier, whose attachment may render target proteins a signature leading to their subsequent ubiquitination, thereby recruits proteasome to degrade them.