Cellular and Molecular Life Sciences最新文献

Mitochondrial function and its regulation within the placenta are critical for maintaining a healthy pregnancy. This study investigated the role of G-protein signaling 12 (RGS12) in placental mitochondrial function and pregnancy outcomes. RGS12 was found to be localized within the mitochondria of placental trophoblast cells. RGS12 knockdown in human placental cells resulted in decreased mitochondrial abundance, impaired oxidative phosphorylation, and reduced antioxidant capacity. Mechanistically, RGS12 enhanced the function of ATP5B, a key mitochondrial enzyme, by promoting its tyrosine phosphorylation. In a mouse model, placental RGS12 deficiency led to reduced tolerance to preterm birth (PTB) challenge, decreased fetal weight, and trophoblast cell death. These adverse effects were associated with diminished ATP synthase activity and activation of the p38MAPK signaling pathway, while restoring RGS12 expression improved the phenotype of mitochondrial dysfunction in placental trophoblast cells. Furthermore, reduced RGS12 expression and impaired mitochondrial function were observed in placentas from cases experiencing PTB. Collectively, these findings provide hitherto undocumented evidence of a specific molecular mechanism by which placental mitochondrial dysfunction contributes to adverse pregnancy outcomes. Our study suggests that RGS12 may represent a novel therapeutic target for improving pregnancy outcomes through its role in regulating placental mitochondrial function.

Objectives: Clarify the role of progranulin (PGRN) in renal fibrosis and its regulatory mechanism on macrophage efferocytosis.

Methods: To investigate the effect of PGRN on renal fibrosis, construct PGRN-deficient (PGRN^-/-) mice and establish a renal fibrosis model induced by unilateral ureteral obstruction (UUO). The degree of kidney injury and fibrosis was evaluated through histological examination, immunohistochemical detection, enzyme-linked immunosorbent assay, and TUNEL assay. To evaluate the effect of PGRN on the efferocytosis ability, BMDMs extracted from PGRN^-/- mice were co-cultured with apoptotic HK-2 cells. Efferocytosis activity was evaluated by flow cytometry and immunofluorescence. To analyze the molecular mechanism, conduct a transcriptomics analysis. The protein binding relationship was verified through co-immunoprecipitation and molecular docking. The changes in PGRN after interfering with signaling pathways were detected by qRT-PCR and Western blotting.

Results: The deficiency of PGRN significantly alleviated the renal tubular damage and tubular apoptosis induced by UUO. Additionally, it was observed that the infiltration of Mertk^{^+}CD68^{^+} macrophages increased, indicating that PGRN knockout enhanced phagocytosis. In vitro experiments showed that PGRN knockout BMDMs had enhanced phagocytosis of apoptotic HK2. Sequencing results revealed significant differences in the JAK-STAT pathway. Further studies found that the functional effect of this pathway was mainly mediated by STAT1/2, and overexpression of STAT1/2 reversed the enhanced phagocytosis induced by PGRN deficiency, rather than JAK. Mechanistically, PGRN directly binds to PPAR-δ, and its absence upregulates PPAR-δ, inhibiting the downstream expression of STAT1/2, thereby enhancing phagocytosis. However, knocking down or mutating PPAR-δ eliminates this effect.

Conclusion: PGRN inhibits macrophage efferocytosis during renal fibrosis by binding and inhibiting PPAR-δ, thereby activating the STAT1/2 signaling pathway and impairing the clearance of apoptotic cells.

This study aims to elucidate the synergistic protective mechanism of the AMPK agonist 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) in ischemia-reperfusion injury -associated acute kidney injury (IRI-AKI). By establishing a hypoxia/reoxygenation (H/R) injury model using human proximal tubule cells (HK-2) and IRI-AKI rat model, and employing molecular techniques including qRT-PCR, western blotting, serum biochemical assays, renal tissue hematoxylin and eosin staining, immunofluorescence, and transmission electron microscopy (TEM), we demonstrated that AICAR activates AMPK, leading to the significant downregulation of TXNIP and NLRP3, blocks Caspase-1-dependent release of IL-1β and IL-18, and ultimately suppresses pyroptosis, thereby alleviating renal inflammatory injury. Furthermore, AICAR restored mitochondrial membrane potential and ATP levels in H/R-treated HK-2 cells, reduced reactive oxygen species production in renal tissues of IRI-AKI rats, and elevated levels of antioxidant enzymes. Concurrently, utilizing targeted metabolomics technology, we discovered that AICAR effectively restores the levels of multiple metabolites associated with glycolysis, the TCA cycle, the urea cycle, and tryptophan metabolism and alleviates lipid deposition in IRI-AKI. This confirms that AICAR alleviates IRI-AKI by activating AMPK to restore impaired cellular energy metabolism, improve mitochondrial function, and ameliorate oxidative stress. Notably, this study is the first to reveal that AICAR, via AMPK activation, synchronously regulates dual protective pathways: "pyroptosis inhibition" and "energy metabolism remodeling." This synergistic protective mechanism may represent the core advantage distinguishing AICAR from other potential therapeutic strategies, highlighting its substantial translational potential as a multi-mechanism synergistic therapeutic agent. Our findings provide an innovative dual-regulatory ("pyroptosis-energy metabolism") therapeutic strategy for the clinical prevention and treatment of IRI-AKI.

Both Human immunodeficiency virus (HIV) and Epstein-Barr Virus (EBV) are associated with an increased risk of malignancies. HIV infection is associated with EBV reactivation and an increase in EBV viral loads in saliva and blood, and people living with HIV frequently develop EBV-associated B-cell malignancies. In this study, we aimed to investigate the involvement of HIV-1 and EBV co-existence in the development of B-cell malignancies. To do so, we focused our attention on the two viral transcriptional activators (HIV-1 Tat and EBV Zta) and analyzed their possible interaction since they both have cell-penetration domains and can be found simultaneously in the blood or cells of people living with HIV. We investigated the interaction of Tat and Zta using co-immunoprecipitation, in vitro binding, YFP reconstitution assay and FRET. We found that they bind each other in human B cells and blood serum. Tat and Zta interaction was also observed in a serum sample from one HIV-positive individual. YFP reconstitution demonstrated that this interaction occurred predominantly in the nucleus, indicating that it might affect the host genome. We further analyzed the effects of Tat and Zta on primary and EBV-transformed human B cells by RNA-sequencing and found that the combined Tat and Zta action in B cells differed from a single action of the two proteins. A subset of genes, activated by Tat or Zta alone, that trigger an immune response and antigen presentation in B cells, remained unchanged when the two proteins were combined. B cells, treated or transfected with Tat and Zta, exhibited a substantial decrease in HLA-ABC (MHC class I) expression, a critical component of the antigen processing and presentation pathway. Our findings suggest that the reduction of total HLA-ABC levels in B cells upon Tat and Zta interaction might be linked to HLA-ABC proteasomal degradation. Furthermore, HLA-ABC downregulation induced by Tat and Zta interaction conferred protection against cytotoxic T cell recognition of EBV-infected B cells. To conclude, we demonstrated for the first time that HIV-1 Tat and EBV Zta interacted directly in B cells and blood serum; this interaction can be found in people with HIV. This interaction brings about immune evasion of EBV-infected or transformed B cells.