Formaldehyde and De/Methylation in Age-Related Cognitive Impairment.

Formaldehyde (FA) is a highly reactive substance that is ubiquitous in the environment and is usually considered as a pollutant. In the human body, FA is a product of various metabolic pathways and participates in one-carbon cycle, which provides carbon for the synthesis and modification of bio-compounds, such as DNA, RNA, and amino acids. Endogenous FA plays a role in epigenetic regulation, especially in the methylation and demethylation of DNA, histones, and RNA.

Icariin protects SH-SY5Y cells from formaldehyde-induced injury through suppression of Tau phosphorylation.

Objective: To investigate the neuroprotective effects of icariin on formaldehyde (FA)-treated human neuroblastoma SH-SY5Y cells and the possible mechanisms involved.

Methods: SH-SY5Y cells were divided into FA treatment group, FA treatment group with icariin, and the control group. Cell viability, apoptosis, and morphological changes were determined by cell counting kit-8 (CCK 8), flow cytometry, and confocal microscopy, respectively.

Alzheimer's disease and methanol toxicity (part 2): lessons from four rhesus macaques (Macaca mulatta) chronically fed methanol.

A recently established link between formaldehyde, a methanol metabolite, and Alzheimer's disease (AD) pathology has provided a new impetus to investigate the chronic effects of methanol exposure. This paper expands this investigation to the non-human primate, rhesus macaque, through the chronic feeding of young male monkeys with 3% methanol ad libitum. Variable Spatial Delay Response Tasks of the monkeys found that the methanol feeding led to persistent memory decline in the monkeys that lasted 6 months beyond the feeding regimen.

Alzheimer's disease and methanol toxicity (part 1): chronic methanol feeding led to memory impairments and tau hyperphosphorylation in mice.

Although methanol toxicity is well known for acute neurological sequelae leading to blindness or death, there is a new impetus to investigate the chronic effects of methanol exposure. These include a recently established link between formaldehyde, a methanol metabolite, and Alzheimer's disease (AD) pathology. In the present study, mice were fed with methanol to revisit the chronic effects of methanol toxicity, especially as it pertains to AD progression.

Hyperphosphorylation results in tau dysfunction in DNA folding and protection.

Hyperphosphorylation of tau occurs in preclinical and clinical stages of Alzheimer's disease (AD), and hyperphosphorylated tau is the main constituent of the paired helical filaments in the brains of mild cognitive impairment and AD patients. While most of the work described so far focused on the relationship between hyperphosphorylation of tau and microtubule disassembly as well as axonal transport impairments, both phenomena ultimately leading to cell death, little work has been done to study the correlation between tau hyperphosphorylation and DNA damage. As we showed in this study, tau hyperphosphorylation and DNA damage co-occurred under formaldehyde treatment in N2a cells, indicating that phosphorylated tau (p-Tau) induced by formaldehyde may be involved in DNA impairment.

Formaldehyde induces hyperphosphorylation and polymerization of Tau protein both in vitro and in vivo.

Background: Chronic formaldehyde exposure leads to memory impairment and abnormal elevation of endogenous formaldehyde has been found in the brains of Alzheimer's disease (AD) patients. Hyperphosphorylated Tau protein with subsequent aggregates as neurofibrillary tangles (NFTs) is one of the typical pathological characteristics in AD brains. The mechanism underlying abnormally elevated concentrations of endogenous formaldehyde that induce Tau hyperphosphorylation is unknown.

Formaldehyde stress.

Formaldehyde, one of the most toxic organic compounds, is produced and processed in human cells. The level of human endogenous formaldehyde is maintained at a low concentration (0.01-0.