Tetramethylpyrazine Nitrone Promotes the Clearance of Alpha-Synuclein via Nrf2-Mediated Ubiquitin-Proteasome System Activation.

Aggregation of α-synuclein (α-syn) and α-syn cytotoxicity are hallmarks of sporadic and familial Parkinson's disease (PD). Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent enhancement of the expression of the 20S proteasome core particles (20S CPs) and regulatory particles (RPs) increases proteasome activity, which can promote α-syn clearance in PD. Activation of peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) may reduce oxidative stress by strongly inducing Nrf2 gene expression. In the present study, tetramethylpyrazine nitrone (TBN), a potent-free radical scavenger, promoted α-syn clearance by the ubiquitin-proteasome system (UPS) in cell models overexpressing the human A53T mutant α-syn. In the α-syn transgenic mice model, TBN improved motor impairment, decreased the products of oxidative damage, and down-regulated the α-syn level in the serum. TBN consistently up-regulated PGC-1α and Nrf2 expression in tested models of PD. Additionally, TBN similarly enhanced the proteasome 20S subunit beta 8 (Psmb8) expression, which is linked to chymotrypsin-like proteasome activity. Furthermore, TBN increased the mRNA levels of both the 11S RPs subunits Pa28αß and a proteasome chaperone, known as the proteasome maturation protein (Pomp). Interestingly, specific siRNA targeting of Nrf2 blocked TBN's effects on Psmb8, Pa28αß, Pomp expression, and α-syn clearance. In conclusion, TBN promotes the clearance of α-syn via Nrf2-mediated UPS activation, and it may serve as a potentially disease-modifying therapeutic agent for PD.

Diagnostic utility and sensitivities of matrix Gla protein (MGP), TRPS1 and GATA3 in breast cancer: focusing on metastatic breast cancer, invasive breast carcinoma with special features, and salivary gland-type tumours.

Matrix Gla protein (MGP) and trichorhinophalangeal syndrome type 1 (TRPS1) have recently emerged as novel breast-specific immunohistochemical (IHC) markers, particularly for triple-negative breast cancer (TNBC) and metaplastic carcinoma. The present study aimed to validate and compare the expression of MGP, TRPS1 and GATA binding protein 3 (GATA3) in metastatic breast carcinoma (MBC), invasive breast carcinoma (IBC) with special features, including special types of invasive breast carcinoma (IBC-STs) and invasive breast carcinoma of no special type with unique features, and mammary and non-mammary salivary gland-type tumours (SGTs). Among all enrolled cases, MGP, TRPS1 and GATA3 had comparable high positivity for ER/PR-positive (p=0.148) and HER2-positive (p=0.310) breast carcinoma (BC), while GATA3 positivity was significantly lower in TNBC (p<0.001). Similarly, the positive rates of MGP and TRPS1 in MBCs (99.4%), were higher than in GATA3 (90.9%, p<0.001). Among the IBC-STs, 98.4% of invasive lobular carcinomas (ILCs) were positive for all three markers. Among neuroendocrine tumours (NTs), all cases were positive for TRPS1 and GATA3, while MGP positivity was relatively low (81.8%, p=0.313). In the neuroendocrine carcinoma (NC) subgroup, all cases were positive for GATA3 and MGP, while one case was negative for TRPS1. All carcinomas with apocrine differentiation (APOs) were positive for GATA3 and MGP, while only 60% of the cases demonstrated moderate staining for TRPS1. Among mammary SGTs, MGP demonstrated the highest positivity (100%), followed by TRPS1 (96.0%) and GATA3 (72.0%). Positive staining for these markers was also frequently observed in non-mammary SGTs. Our findings further validate the high sensitivity of MGP and TRPS1 in MBCs, IBC-STs, and breast SGTs. However, none of these markers are capable of distinguishing between mammary and non-mammary SGTs.

ApoE4 dysregulation incites depressive symptoms and mitochondrial impairments in mice.

Apolipoprotein E4 (ApoE4) is involved in the stress-response processes and is hypothesized to be a risk factor for depression by means of mitochondrial dysfunction. However, their exact roles and underlying mechanisms are largely unknown. ApoE4 transgenic mice (B6. Cg-ApoEtm1Unc Cdh18Tg( GFAP-APOE i4)1Hol /J) were subjected to stress (lipopolysaccharides, LPS) to elucidate the aetiology of ApoE4-induced depression. LPS treatment significantly aggravated depression-like behaviours, concurrent with neuroinflammation and impaired mitochondrial changes, and melatonin/Urolithin A (UA) + 5-aminoimidazole-4-carboxamide 1-ß-D-ribofuranoside (AICAR) reversed these effects in ApoE4 mice. Concurrently, ApoE4 mice exhibited mitophagy deficits, which could be further exacerbated by LPS stimulation, as demonstrated by reduced Atg5, Beclin-1 and Parkin levels, while PINK1 levels were increased. However, these changes were reversed by melatonin treatment. Additionally, proteomic profiling suggested mitochondria-related signalling and network changes in ApoE4 mice, which may underlie the exaggerated response to LPS. Furthermore, HEK 293T cells transfected with ApoE4 showed mitochondria-associated protein and mitophagy defects, including PGC-1α, TFAM, p-AMPKα, PINK1 and LC3B impairments. Additionally, it aggravates mitochondrial impairment (particularly mitophagy), which can be attenuated by triggering autophagy. Collectively, ApoE4 dysregulation enhanced depressive behaviour upon LPS stimulation.