Oxidative stress in depression is a prime cause of neurotransmitter metabolism dysfunction in the brain. Acetylcholinesterase (AChE), a key hydrolase in the cholinergic system, directly determines the degradation of neurotransmitters. However, due to the complexity of the brain and lack of appropriate in situ imaging tools, the mechanism underlying the changes in AChE activity in depression remains unclear. Hence, we generated a twophoton fluorescence probe (MCYN) for real-time visualization of AChE with excellent sensitivity and selectivity. AChE can specifically recognize and cleave the carbamic acid ester bond in MCYN, and MCYN emits bright fluorescence at 560 nm by two-photon excitation at 800 nm. By utilizing MCYN to monitor AChE, we discovered a significant increase in AChE activity in the brains of mice with depression phenotypes. Notably, with the assistance of a two-photon fluorescence imaging probe of the superoxide anion radical (O 2•− ), in vivo visualization for the first time revealed the positive correlation between AChE and O 2•− levels associated with depressive behaviors. This finding suggests that oxidative stress may induce AChE overactivation, leading to depression-related behaviors. This work provides a new and rewarding perspective to elucidate the role of oxidative stress regulating AChE in the pathology of depression.

Recent studies have thoroughly described genome-wide expression patterns defining molecular subtypes of pancreatic ductal adenocarcinoma (PDAC), with different prognostic and predictive implications. Although the reversible nature of key regulatory transcription circuits defining the two extreme PDAC subtype lineages “classical” and “basal-like” suggests that subtype states are not permanently encoded but underlie a certain degree of plasticity, pharmacologically actionable drivers of PDAC subtype identity remain elusive. Here, we characterized the mechanistic and functional implications of the histone methyltransferase enhancer of zeste homolog 2 (EZH2) in controlling PDAC plasticity, dedifferentiation, and molecular subtype identity. Utilization of transgenic PDAC models and human PDAC samples linked EZH2 activity to PDAC dedifferentiation and tumor progression. Combined RNA- and chromatin immunoprecipitation sequencing studies identified EZH2 as a pivotal suppressor of differentiation programs in PDAC and revealed EZH2-dependent transcriptional repression of the classical subtype defining transcription factor Gata6 as a mechanistic basis for EZH2-dependent PDAC progression. Importantly, genetic or pharmacologic depletion of EZH2 sufficiently increased GATA6 expression, thus inducing a gene signature shift in favor of a less aggressive and more therapy-susceptible, classical PDAC subtype state. Consistently, abrogation of GATA6 expression in EZH2-deficient PDAC cells counteracted the acquisition of classical gene signatures and rescued their invasive capacities, suggesting that GATA6 derepression is critical to overcome PDAC progression in the context of EZH2 inhibition. Together, our findings link the EZH2-GATA6 axis to PDAC subtype identity and uncover EZH2 inhibition as an appealing strategy to induce subtype-switching in favor of a less aggressive PDAC phenotype. Significance: This study highlights the role of EZH2 in PDAC progression and molecular subtype identity and suggests EZH2 inhibition as a strategy to recalibrate GATA6 expression in favor of a less aggressive disease.

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Astaxanthin (AST) is a carotenoid pigment which possesses potent antioxidative, anti-inflammatory, and neuroprotective properties. The aim of this study was to investigate whether administration of AST had protective effects on D-galactose-induced brain aging in rats, and further examined its protective mechanisms. The results showed that AST treatment significantly restored the activities of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD), and increased glutathione (GSH) contents and total antioxidant capacity (T-AOC), but decreased malondialdehyde (MDA), protein carbonylation and 8-hydroxy-2- deoxyguanosine (8-OHdG) levels in the brains of aging rats. Furthermore, AST increased the ratio of Bcl-2/Bax, but decreased the expression of Cyclooxygenase-2 (COX-2) in the brains of aging rats. Additionally, AST ameliorated histopathological changes in the hippocampus and restored brain derived neurotrophic factor (BDNF) levels in both the brains and hippocampus of aging rats. These results suggested that AST could alleviate brain aging, which may be due to attenuating oxidative stress, ameliorating hippocampus damage, and upregulating BDNF expression.

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