The regulation of the mitochondrial apoptotic pathway by glucocorticoid receptor in collaboration with Bcl-2 family proteins in developing T cells

Lariciresinol induces apoptosis in HepG2 cells via mitochondrial-mediated apoptosis pathway

Lariciresinol (LA) is one of the main active ingredients in many traditional medicinal plants such as Patrinia, and has the role of anti-liver cancer. However, the precise mechanisms are unclear. This study investigated the molecular mechanisms of LA against HepG2 cells. LA anti-tumor activity was assessed with the CCK-8, Ki-67, and immunofluorescence staining. Cells apoptotic ratio was evaluated by Annexin V/PI double-staining assay. A proteomic approach was used to identify differentially expressed proteins after LA treatment. JC-1 staining was carried out to detect the mitochondrial membrane potential (ΔΨm), and the Western blot analysis was used to analyse the apoptosis-associated proteins. Our results suggested that LA significantly suppressed the viability of HepG2 cells. The CCK-8 and Ki-67 expression indicated dose-dependent decreases in cell proliferation. Flow cytometry analysis showed that LA exhibited a apoptosis-inducing effect. The proteomic study observed the presence of apoptosis-associated proteins and mitochondrial dysfunction in HepG2 cells after LA-treatment. Further analysis showed that LA could trigger the mitochondrial-mediated apoptosis pathway, based on a decrease in ΔΨm; deliver of cytochrome c; activation of caspase-9/-3 and poly(ADP-ribose) polymerase; and decrease of the proportion of Bcl-2/Bax. Collectively, our studies found that LA exhibits significant cytotoxic effects by inhibiting cell proliferation, inducing apoptosis, possibly via activation of the mitochondrial-mediated apoptosis pathway.

Acute mental stress induces mitochondrial bioenergetic crisis and hyper-fission along with aberrant mitophagy in the gut mucosa in rodent model of stress-related mucosal disease

Psychological stress, depression and anxiety lead to multiple organ dysfunctions wherein stress-related mucosal disease (SRMD) is common to people experiencing stress and also occur as a side effect in patients admitted to intensive care units; however the underlying molecular aetiology is still obscure. We report that in rat-SRMD model, cold restraint-stress severely damaged gut mitochondrial functions to generate superoxide anion (O₂^•-), depleted ATP and shifted mitochondrial fission-fusion dynamics towards enhanced fission to induce mucosal injury. Activation of mitophagy to clear damaged and fragmented mitochondria was evident from mitochondrial translocation of Parkin and PINK1 along with enhanced mitochondrial proteome ubiquitination, depletion of mitochondrial DNA copy number and TOM 20. However, excess and sustained accumulation of O₂^•--generating defective mitochondria overpowered the mitophagic machinery, ultimately triggering Bax-dependent apoptosis and NF-κB-intervened pro-inflammatory mucosal injury. We further observed that stress-induced enhanced serum corticosterone stimulated mitochondrial recruitment of glucocorticoid receptor (GR), which contributed to gut mitochondrial dysfunctions as documented from reduced ETC complex 1 activity, mitochondrial O₂^•- accumulation, depolarization and hyper-fission. GR-antagonism by RU486 or specific scavenging of mitochondrial O₂^•- by a mitochondrially targeted antioxidant mitoTEMPO ameliorated stress-induced mucosal damage. Gut mitopathology and mucosal injury were also averted when the perception of mental stress was blocked by pre-treatment with a sedative or antipsychotic. Altogether, we suggest the role of mitochondrial GR-O₂^•--fission cohort in brain-mitochondria cross-talk during acute mental stress and advocate the utilization of this pathway as a potential target to prevent mitochondrial unrest and gastropathy bypassing central nervous system.

Glucocorticoid hormone treatment enhances the cytokine production of regulatory T cells by upregulation of Foxp3 expression

OBJECTIVE

Despite the fact that glucocorticoids (GC) are important therapeutic tools, their effects on regulatory T cells (Treg) are not well defined. The aim of our work was to investigate how GCs influence in vivo the thymic (tTreg) and peripheral Treg (pTreg) differentiation, survival and cytokine production.

METHODS

Tregs were detected with flow cytometry in lymphatic organs of 4-6 weeks old BALB/c mice after repeated (2-4days), high-dose in vivo GC treatment using CD4/CD25 cell surface and Foxp3/IL-10/TGFβ/glucocorticoid receptor (GR) intracellular staining. Cytokine, Foxp3, and GR mRNA levels of sorted CD4⁺CD25^high T cells were analyzed using RT-PCR. Foxp3 and GR localization in Treg cells was investigated with confocal microscopy.

RESULTS

GC treatment of mice resulted in increased relative tTreg frequency in the thymus, which was due to decreased total thymocyte numbers with unchanged absolute tTreg cell count. In contrast the relative pTreg cell ratio in secondary lymphatic organs decreased or showed no changes after GC treatment, while the absolute number of pTregs decreased. Elevated intracellular IL-10⁺ and TGFβ⁺ tTreg and pTreg ratios were measured in GC-treated animals, accompanied with elevated Foxp3 mRNA expression. In addition, GC treatment caused increased TGFβ and IL-35 mRNA expression in CD4⁺CD25^high+ splenic and elevated IL-10 mRNA level in thymic tTregs. GR expression of thymic tTreg cells was lower than in pTregs. GC treatment caused an opposite change in GR levels, elevating GR in tTregs but decreasing it in pTregs. We observed a nuclear localization of GR in both tTregs and pTregs, which showed high colocalization (∼60%) with Foxp3 transcription factor. These data suggest an interaction of these two transcription factors with further increase due to GC treatment in splenic pTregs.

CONCLUSION

Our data show selective survival of tTregs and elevated production of immunosuppressive cytokines by Treg cells after GC treatment, which may contribute to the immunosuppressive effects of GCs.

Solasodine inhibits human colorectal cancer cells through suppression of the AKT/glycogen synthase kinase-3β/β-catenin pathway

Solasodine is a main active component isolated from Solanum incanum L. that performs a wide range of functions containing anti‐oxidant, anti‐infection, and neurogenesis promotion. In this study, we explored the influence of solasodine on three types of human colorectal cancer (CRC) cell lines. The results show that solasodine prohibited CRC cell proliferation dose‐ and time‐dependently and impeded CRC cell motility by downregulating MMPs. Solasodine was also found to fuel caspase‐cascade reaction and increase the ratio between Bax and Bcl‐2 so as to induce CRC cell apoptosis. When cells were pretreated with AKT activator (insulin‐like growth factor‐1) followed by solasodine, the solasodine‐induced apoptosis was partially abrogated by insulin‐like growth factor‐1. Moreover, solasodine hindered tumor development and stimulated similar mechanisms in vivo. In general, our study provides the first evidence that solasodine has a suppressive effect on CRC cells and that this agent may be a novel therapeutic drug for CRC treatment.

[Association between BIM gene and glucocorticoid resistance in children with acute lymphoblastic leukemia]

Acute lymphoblastic leukemia (ALL) is the most common malignant hematological disease in childhood. Glucocorticoids are frequently used in the chemoradiotherapy regimen for ALL and can induce the apoptosis of ALL cells through several signaling pathways, but about 10% of ALL children have poor response to glucocorticoids. Studies have revealed that glucocorticoids induce the apoptosis of ALL cells by upregulating the expression of BIM gene, and BIM gene is associated with glucocorticoid resistance in childhood ALL. This article reviews the recent studies on glucocorticoid resistance in childhood ALL, especially the role of BIM and its expression products in this process.