Hebei Medical University

Recent studies have shown that anti-ERp5 antibodies inhibit platelet activation and thrombus formation; Moreover, ERp5-deficient platelets exhibit enhanced platelet reactivity via regulation of endoplasmic reticulum (ER) stress. In this study, we used a new ERp5-knockout mouse model as well as recombinant ERp5 (rERp5) protein, to examine the role of ERp5 in platelet function and thrombosis. Although platelet-specific ERp5-deficient mice had decreased platelet count, the mice had shortened tail-bleeding times and enhanced platelet accumulation in FeCl₃-induced mesenteric artery injury, compared with wild-type mice. Using platelet-specific ERp5-deficient mice, we found that ERp5 deficiency increased platelet aggregation, granule secretion, and integrin αIIbβ3 activation. Wild-type recombinant ERp5 protein (rERp5-wt) and inactive mutant ERp5 protein (rERp5-mut) both inhibited human platelet aggregation and the binding of fibrinogen to human platelets, indicating that ERp5 protein interferes with the interaction between integrin αIIbβ3 and its ligand fibrinogen, and its enzymatic activity is not required for this process. Consistently, wild-type mice injected with rERp5-wt or rERp5-mut protein had prolonged tail-bleeding times. Our results provide important evidence that platelet ERp5 negatively regulates platelet activation and thrombus formation, via steric hindrance interfering with integrin αIIbβ3 ligation.

While NDUFAF6 is implicated in breast cancer, its specific role remains unclear.

The expression levels and prognostic significance of NDUFAF6 in breast cancer were assessed using The Cancer Genome Atlas, Gene Expression Omnibus, Kaplan-Meier plotter and cBio-Portal databases. We knocked down NDUFAF6 in breast cancer cells using small interfering RNA and investigated its effects on cell proliferation and migration ability. We performed gene expression analysis and validated key findings using protein analysis. We also assessed mitochondrial activity and cellular metabolism.

NDUFAF6 was highly expressed in breast cancer, which was associated with a poorer prognosis. Knockdown of NDUFAF6 reduced the proliferation and migration ability of breast cancer cells. Transcriptome analysis revealed 2,101 differentially expressed genes enriched in apoptosis and mitochondrial signaling pathways. Western blot results showed NDUFAF6 knockdown enhanced apoptosis. In addition, differential gene enrichment analysis was related to mitochondrial signaling pathways, and western blot results verified that mitophagy was enhanced in NDUFAF6 knockdown breast cancer cells. JC-1 assay also showed that mitochondrial dysfunction and reactive oxygen species content were increased after knocking down NDUFAF6. In addition, basal and maximal mitochondrial oxygen consumption decreased, and intracellular glycogen content increased.

Knockdown of NDUFAF6 resulted in apoptosis and mitophagy in breast cancer cells and NDUFAF6 may be a potential molecular target for breast cancer therapy.

The effects of granulose cell (GC) senescence on premature ovarian insufficiency/premature ovarian failure have been extensively examined, the association between GC senescence and ovarian aging remains to be clarified.

Human and mouse GCs from young/control and old/advanced maternal age (AMA) groups were collected, and GC senescence was determined. The role of the DNMT1-p53 axis in GC senescence during ovarian aging was examined and validated in a KGN cell senescence model.

SA-beta-gal-positive GCs were significantly increased in the AMA group, accompanied by activation of the p53-p21 pathway, which was also found in GCs from aged mice and H₂O₂-induced senescent KGN cells. Pyrosequencing methylation analysis revealed that increased expression of p53 was associated with decreased average methylation levels of CpG sites (-1031, -1019, -1012 and -1008) within the P53 promoter CpG island in senescenct GCs and KGN cells. We further found that decreased DNA-methyltransferase 1 (DNMT1) expression was responsible for the reduced methylation levels of the CpG sites.

Decreased DNMT1 with hypomethylation of the CpG sites within the P53 promoter CpG island in GCs is involved in ovarian aging.