ABSTRACT
Objective:To evaluate the role of signal transducer and activator of transcription 3 (STAT3)/nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy in salidroside-induced attenuation of intestinal ischemia-reperfusion (I/R) injury in mice and the relationship with ferroptosis.Methods:Thirty-six SPF-grade healthy male C57BL mice, aged 6-8 weeks, weighing 20-25 g, were divided into 6 groups ( n=6 each) by a random number table method: sham operation group (S group), sham operation+ salidroside group (SS group), intestinal I/R group (IR group), intestinal I/R+ salidroside group (IS group), intestinal I/R+ salidroside+ autophagy activator rapamycin group (ISR group) and intestinal I/R+ salidroside+ STAT3 activator colivelin group (ISC group). The intestinal I/R injury model was established by clamping the superior mesenteric artery for 45 min followed by 30-min reperfusion in IR, IS, ISR and ISC groups, while the superior mesenteric artery was only isolated without clipping in S and SS groups. At 1 week before developing the model, salidroside 40 mg/kg was intraperitoneally injected once a day for 7 consecutive days in SS, IS, ISC and ISR groups, rapamycin 4 mg/kg was intraperitoneally injected once a day for 7 consecutive days in group ISR, colivelin 1 mg/kg was intraperitoneally injected once a day for 7 consecutive days in group ISC, while the equal volume of normal saline was given instead in the rest two groups. The mice were sacrificed at 30 min of reperfusion, and intestinal tissues were obtained for examination of the pathological changes after HE staining (with a optical microscope) which were scored according to Chiu and for determination of contents of malondialdehyde (MDA), Fe 2+, glutathione (GSH) and reactive oxygen species (ROS), activity of superoxide dismutase (SOD) and expression of p-STAT3, STAT3, glutathione peroxidase 4 (GPX4), NCOA4 and ferritin heavy chain 1 (FTH1) in intestinal tissues (by Western blot). Results:Compared with group S, the Chiu′s score and contents of MDA, Fe 2+ and ROS were significantly increased, the content of GSH was decreased, the activity of SOD was decreased, the expression of p-STAT3 and NCOA4 was up-regulated, the expression of GPX4 and FTH1 was down-regulated, the p-STAT3/STAT3 ratio was increased ( P<0.05), pathological injury was found in intestinal tissues, and no significant change was found in the aforementioned indexes in group IR( P>0.05). Compared with group IR, the Chiu′s score and contents of MDA, Fe 2+ and ROS were significantly decreased, GSH content was increased, SOD activity was increased, the expression of p-STAT3 and NCOA4 was down-regulated, the expression of GPX4 and FTH1 was up-regulated, p-STAT3/STAT3 ratio was decreased ( P<0.05), and the pathological injury was significantly alleviated in intestinal tissues in group IS. Compared with group IS, the Chiu′s score and contents of MDA, Fe 2+ and ROS were significantly increased, GSH content was decreased, SOD activity was decreased, the expression of p-STAT3 and NCOA4 was up-regulated, the expression of GPX4 and FTH1 was down-regulated, p-STAT3/STAT3 ratio was increased ( P<0.05), and the pathological injury was aggravated in intestinal tissues in ISR and ISC groups. There was no statistically significant difference in the expression of STAT3 among the five groups ( P>0.05). Conclusions:STAT3/NCOA4-mediated ferritinophagy is involved in the process of salidroside-induced reduction of intestinal I/R injury in mice, which may be related to inhibiting ferroptosis.
ABSTRACT
RAC3 pertenece a la familia de coactivadores de receptores nucleares p160, y se encuentra sobreexpresado en varios tumores. Demostramos previamente que RAC3 es coactivador del factor de transcripción anti-apoptótico NF-kB. En este trabajo investigamos su rol en la apoptosis inducida por H2O2 en una línea celular no tumoral derivada de riñón embrionario humano (HEK293), y por el ligando inductor de apoptosis relacionado a TNF (TRAIL) en una línea de leucemia mieloide crónica humana (K562), naturalmente resistente a la muerte por este estímulo. Observamos que las células tumorales K562 poseen niveles altos de RAC3 comparados con las células no tumorales HEK293. La sobreexpresión normal de coactivador o por transfección, inhibe la apoptosis mediante una disminución de la activación de caspasas, translocación del factor inductor de apoptosis (AIF) al núcleo, aumento de la actividad de NF-kB y las quinasas AKT y p38 y disminución de la quinasa ERK. Lo opuesto fue observado por disminución de RAC3 mediante la técnica de ARN interferente (RNAi) en K562, aumentando así la apoptosis inducida por TRAIL. Estas evidencias sugieren que una sobreexpresión de RAC3 contribuye al desarrollo de tumores, participando en las cascadas que controlan la muerte celular por mecanismos no estrictamente dependientes de hormonas esteroideas y/o de acetilación, constituyendo esto un posible blanco de ataque para el tratamiento de tumores.
RAC3 belongs to the family of p160 nuclear receptors coactivators and it is over-expressed in several tumors. We have previously shown that RAC3 is a NF-kB coactivator. In this paper, we investigated the role of RAC3 in cell-sensitivity to apoptosis, using H2O2 in the human embryonic kidney cell line (HEK293), and tumor necrosis factor-related apoptosis inducing ligand (TRAIL) in a human chronic myeloid leukemia cell line (K562) naturally resistant to TRAIL. We observed that the tumoral K562 cells have high levels of RAC3 if compared with the non-tumoral HEK293 cells. The normal or transfected coactivator over-expression inhibits apoptosis through a diminished caspase activity and AIF nuclear translocation, increased NF-kB, AKT and p38, and decreased ERK activities. In contrast, inhibition of RAC3 by siRNA induced sensitivity of K562 to TRAIL-induced apoptosis. Such results suggest that over-expression of RAC3 contributes to tumor development through molecular mechanisms that do not depend strictly on acetylation and/or steroid hormones, which control cell death. This could be a possible target for future tumor therapies.