Regulation of 8-Hydroxydaidzein in IRF3-Mediated Gene Expression in LPS-Stimulated Murine Macrophages

Daidzein ameliorates nonmotor symptoms of manganese-induced Parkinsonism in zebrafish model: Behavioural and biochemical approach

BACKGROUND AND PURPOSE

Parkinson's disease (PD) is a prevalent neurodegenerative movement disorder characterized by motor dysfunction. Environmental factors, especially manganese (Mn), contribute significantly to PD. Existing therapies are focused on motor coordination, whereas nonmotor features such as neuropsychiatric symptoms are often neglected. Daidzein (DZ), a phytoestrogen, has piqued interest due to its antioxidant, anti-inflammatory, and anxiolytic properties. Therefore, we anticipate that DZ might be an effective drug to alleviate the nonmotor symptoms of Mn-induced Parkinsonism.

EXPERIMENTAL APPROACH

Naïve zebrafish were exposed to 2 mM of Mn for 21 days and intervened with DZ. Nonmotor symptoms such as anxiety, social behaviour, and olfactory function were assessed. Acetylcholinesterase (AChE) activity and antioxidant enzyme status were measured from brain tissue through biochemical assays. Dopamine levels and histology were performed to elucidate neuroprotective mechanism of DZ.

KEY RESULTS

DZ exhibited anxiolytic effects in a novel environment and also improved intra and inter fish social behaviour. DZ improved the olfactory function and response to amino acid stimuli in Mn-induced Parkinsonism. DZ reduced brain oxidative stress and AChE activity and prevented neuronal damage. DZ increased DA level in the brain, collectively contributing to neuroprotection.

CONCLUSION AND IMPLICATIONS

DZ demonstrated a promising effect on alleviating nonmotor symptoms such as anxiety and olfactory dysfunction, through the mitigation of cellular damage. These findings underscore the therapeutic potential of DZ in addressing nonmotor neurotoxicity induced by heavy metals, particularly in the context of Mn-induced Parkinsonism.

p38-dependent c-Jun degradation contributes to reduced PGE2 production in sodium orthovanadate-treated macrophages

In particular, the phenomenon of c-Jun degradation within the inflammatory response has not yet been fully analyzed. In order to verify this, we investigated LPS-stimulated murine macrophages pre-treated with sodium orthovanadate (SO) in order to uncover the regulatory mechanisms of the MAPKs which regulate c-Jun degradation within the inflammatory response. Through our study, we found that SO suppressed the production of prostaglandin E₂ (PGE₂) and the expression of COX-2 in LPS-stimulated RAW264.7 cells. Additionally, SO decreased total c-Jun levels, without altering the amount of mRNA, although the phospho-levels of p38, ERK, and JNK were strongly enhanced. Through the usage of selective MAPK inhibitors, and knockdown and overexpression strategies, p38 was revealed to be a major MAPK which regulates c-Jun degradation. Further analysis indicates that the phosphorylation of p38 is a determinant for c-Jun degradation, and is sufficient to induce ubiquitination-dependent c-Jun degradation, recovered through MG132 treatment. Therefore, our results suggest that the hyperphosphorylation of p38 by SO contributes to c-Jun degradation, which is linked to the suppression of PGE₂ secretion in inflammatory responses; and thus, finding drugs to increase p38 activity could be a novel strategy for the development of anti-inflammatory drugs.

Caragana rosea Turcz Methanol Extract Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Suppressing the TLR4/NF-κB/IRF3 Signaling Pathways

Caragana rosea Turcz, which belongs to the Leguminosae family, is a small shrub found in Northern and Eastern China that is known to possess anti-inflammatory properties and is used to treat fever, asthma, and cough. However, the underlying molecular mechanisms of its anti-inflammatory effects are unknown. Therefore, we used lipopolysaccharide (LPS) in RAW264.7 macrophages to investigate the molecular mechanisms that underlie the anti-inflammatory activities of a methanol extract of Caragana rosea (Cr-ME). We showed that Cr-ME reduced the production of nitric oxide (NO) and mRNA levels of iNOS, TNF-α, and IL-6 in a concentration-dependent manner. We also found that Cr-ME blocked MyD88- and TBK1-induced NF-κB and IRF3 promoter activity, suggesting that it affects multiple targets. Moreover, Cr-ME reduced the phosphorylation levels of IκBα, IKKα/β and IRF3 in a time-dependent manner and regulated the upstream NF-κB proteins Syk and Src, and the IRF3 protein TBK1. Upon overexpression of Src and TBK1, Cr-ME stimulation attenuated the phosphorylation of the NF-κB subunits p50 and p65 and IRF3 signaling. Together, our results suggest that the anti-inflammatory activity of Cr-ME occurs by inhibiting the NF-κB and IRF3 signaling pathways.

TANK Promotes Pressure Overload Induced Cardiac Hypertrophy via Activating AKT Signaling Pathway

Background: TANK (TRAF family member associated NF-κB activator) acts as a member of scaffold proteins participated in the development of multiple diseases. However, its function in process of cardiac hypertrophy is still unknown.

Methods and Results: In this study, we observed an increased expression of TANK in murine hypertrophic hearts after aortic banding, suggesting that TANK may be involved in the pathogenesis of cardiac hypertrophy. We generated cardiac-specific TANK knockout mice, and subsequently subjected to aortic banding for 4–8 weeks. TANK knockout mice showed attenuated cardiac hypertrophy and dysfunction compared to the control group. In contrast, cardiac-specific TANK transgenic mice showed opposite signs. Consistently, in vitro experiments revealed that TANK knockdown decreased the cell size and expression of hypertrophic markers. Mechanistically, AKT signaling was inhibited in TANK knockout mice, but activated in TANK transgenic mice after aortic banding. Blocking AKT signaling with a pharmacological AKT inhibitor alleviated the cardiac hypertrophy and dysfunction in TANK transgenic mice.

Conclusions: Collectively, we identified TANK accelerates the progression of pathological cardiac hypertrophy and is a potential therapeutic target.