Overexpression of fibroblast growth factor 13 ameliorates amyloid-β-induced neuronal damage

Overexpression of ATF4 Inhibits Ferroptosis to Alleviate Anxiety Disorders by Activating the TGF-β Signaling Pathway

Background

Anxiety disorders seriously impair patients' mental health and quality of life, with limited effectiveness of current treatments. Dysregulation of activating transcription factor 4 (ATF4) is involved in various mental diseases, but the research on its potential roles in alleviating anxiety disorders remains limited.

Methods

ATF4 was screened out by bioinformatic analysis and its expression was verified in vivo. Mice were treated with 21 d of chronic restraint stress to establish the anxiety mice model. The anxiolytic effect of ATF4 was assessed by a battery of behavior tests and evaluation of hippocampal tissue damage after overexpressing ATF4. Ferroptosis-related indicators were detected by enzyme-linked immunosorbent assay and Western blotting. Then the transforming growth factor beta (TGF-β) signaling pathway was predicted as the downstream regulatory pathway of ATF4 by bioinformatic methods. Western blotting was conducted to detect the protein expression level of TGF-β1, small mothers against decapentaplegic 3 (Smad3), and phospho-Smad3 (p-Smad3).

Results

ATF4 was screened out as a ferroptosis-related anxiolytic gene after bioinformatics analysis and was down-regulated in the anxiety mice model. Mice with ATF4 overexpression spent more time in the open arms in the elevated plus-maze test, appeared more frequently in the central area in the open-field test, and decreased the immobility time in the forced swimming and tail suspension tests. Hippocampal tissue damage was alleviated, ferroptosis was suppressed, and the levels of TGF-β1 and p-Smad3/Smad3 were increased by AFT4 overexpression.

Conclusion

ATF4 overexpression can repress ferroptosis to improve anxiety disorders by activating the TGF-β signaling pathway.

Escape from X-chromosome inactivation and sex differences in Alzheimer's disease

Sex differences exist in the onset and progression of Alzheimer's disease. Globally, women have a higher prevalence, while men with Alzheimer's disease experience earlier mortality and more pronounced cognitive decline than women. The cause of sex differences in Alzheimer's disease remains unclear. Accumulating evidence suggests the potential role of X-linked genetic factors in the sex difference of Alzheimer's disease (AD). During embryogenesis, a remarkable process known as X-chromosome inactivation (XCI) occurs in females, leading to one of the X chromosomes undergoing transcriptional inactivation, which balances the effects of two X chromosomes in females. Nevertheless, certain genes exceptionally escape from XCI, which provides a basis for dual expression dosage of specific genes in females. Based on recent research findings, we explore key escape genes and their potential therapeutic use associated with Alzheimer's disease. Also, we discuss their possible role in driving the sex differences in Alzheimer's disease. This will provide new perspectives for precision medicine and gender-specific treatment of AD.

Protective Effects of Heat-Killed Ruminococcus albus against β-Amyloid-Induced Apoptosis on SH-SY5Y Cells

A high level of β-amyloid (Aβ) in the brains of patients with Alzheimer's disease (AD) generates reactive oxygen species that induce neuronal death and DNA damage. The interaction between the gut microbiota and brain health has attracted attention in recent years. Heat-killed Ruminococcus albus (hkRA) reportedly protects neurons against damage induced by oxidative stress. However, whether hkRA can inhibit Aβ-induced apoptosis and thus alleviate AD remains unclear. Hence, we aimed to evaluate the protective effects of hkRA against Aβ-induced apoptosis on the human neuroblastoma SH-SY5Y cell. HkRA treatment (108 cells/ml) significantly decreased the Aβ-induced cytotoxicity and DNA damage in the SH-SY5Y cells. It also showed a significant increase of the bax/bcl-2 ratio in the Aβ-treated SH-SY5Y cells. Moreover, hkRA treatment stimulated the expression of antioxidation-related genes HO-1, Nrf2, and PKC-δ and increased the expression of brain-derived neurotrophic factor (BDNF). Meanwhile, it significantly decreased the activity of caspase-3 and protein expression of cleaved caspase-3 in the Aβ-treated SH-SY5Y cells. Additionally, the protein levels of mitochondrial and cytosolic cytochrome c increased and decreased, respectively, in the cells. These results suggest that hkRA protects human neuroblastoma cells from Aβ-induced apoptosis and oxidative stress. Thus, hkRA may be developed into a health-promoting paraprobiotic (the inactivated microbial cells of probiotics) for patients with AD.

Oxygen metabolism abnormality and Alzheimer's disease: An update

Oxygen metabolism abnormality plays a crucial role in the pathogenesis of Alzheimer's disease (AD) via several mechanisms, including hypoxia, oxidative stress, and mitochondrial dysfunction. Hypoxia condition usually results from living in a high-altitude habitat, cardiovascular and cerebrovascular diseases, and chronic obstructive sleep apnea. Chronic hypoxia has been identified as a significant risk factor for AD, showing an aggravation of various pathological components of AD, such as amyloid β-protein (Aβ) metabolism, tau phosphorylation, mitochondrial dysfunction, and neuroinflammation. It is known that hypoxia and excessive hyperoxia can both result in oxidative stress and mitochondrial dysfunction. Oxidative stress and mitochondrial dysfunction can increase Aβ and tau phosphorylation, and Aβ and tau proteins can lead to redox imbalance, thus forming a vicious cycle and exacerbating AD pathology. Hyperbaric oxygen therapy (HBOT) is a non-invasive intervention known for its capacity to significantly enhance cerebral oxygenation levels, which can significantly attenuate Aβ aggregation, tau phosphorylation, and neuroinflammation. However, further investigation is imperative to determine the optimal oxygen pressure, duration of exposure, and frequency of HBOT sessions. In this review, we explore the prospects of oxygen metabolism in AD, with the aim of enhancing our understanding of the underlying molecular mechanisms in AD. Current research aimed at attenuating abnormalities in oxygen metabolism holds promise for providing novel therapeutic approaches for AD.