ABSTRACT
Intestinal ischemiaâreperfusion (IIR) injury is a common complication of surgery, but clear molecular insights and valuable therapeutic targets are lacking. Mitochondrial calcium overload is an early sign of various diseases and is considered a vital factor in ischemiaâreperfusion injury. The mitochondrial calcium uniporter (MCU), which is located on the inner mitochondrial membrane, is the primary mediator of calcium ion entry into the mitochondria. However, the specific mechanism of MCU in IIR injury remains to be clarified. In this study, we generated an IIR model using C57BL/6 mice and Caco-2 cells and found increases in the calcium levels and MCU expression following IIR injury. The specific inhibition of MCU markedly attenuated IIR injury. Moreover, MCU knockdown alleviates mitochondrial dysfunction by reducing oxidative stress and apoptosis. Mechanistically, MCU knockdown substantially reduced the translocation of Drp1 and thus its binding to Fis1 receptors, resulting in decreased mitochondrial fission. Taken together, our findings demonstrated that MCU is a novel upstream regulator of Drp1 in ischemiaâreperfusion and represents a predictive and therapeutic target for IIR.
Subject(s)
Apoptosis , Calcium Channels , Dynamins , Mice, Inbred C57BL , Mitochondria , Mitochondrial Dynamics , Reperfusion Injury , Animals , Humans , Male , Mice , Apoptosis/genetics , Caco-2 Cells , Calcium/metabolism , Calcium Channels/metabolism , Calcium Channels/genetics , Disease Models, Animal , Dynamins/metabolism , Dynamins/genetics , Intestines/blood supply , Intestines/pathology , Membrane Proteins/metabolism , Membrane Proteins/genetics , Mitochondria/metabolism , Mitochondria/pathology , Mitochondria/genetics , Mitochondrial Dynamics/genetics , Mitochondrial Proteins/metabolism , Mitochondrial Proteins/genetics , Oxidative Stress , Reperfusion Injury/metabolism , Reperfusion Injury/genetics , Reperfusion Injury/pathology , Reperfusion Injury/prevention & controlABSTRACT
Ischemia-reperfusion (IR) injury is primarily characterized by the restoration of blood flow perfusion and oxygen supply to ischemic tissue and organs, but it paradoxically leads to tissue injury aggravation. IR injury is a challenging pathophysiological process that is difficult to avoid clinically and frequently occurs during organ transplantation, surgery, shock resuscitation, and other processes. The major causes of IR injury include increased levels of free radicals, calcium overload, oxidative stress, and excessive inflammatory response. Ghrelin is a newly discovered brain-intestinal peptide with anti-inflammatory and antiapoptotic effects that improve blood supply. The role and mechanism of ghrelin in intestinal ischemia-reperfusion (IIR) injury remain unclear. We hypothesized that ghrelin could attenuate IIR-induced oxidative stress and apoptosis. To investigate this, we established IIR by using a non-invasive arterial clip to clamp the root of the superior mesenteric artery (SMA) in mice. Ghrelin was injected intraperitoneally at a dose of 50 µg/kg 20 min before IIR surgery, and [D-Lys3]-GHRP-6 was injected intraperitoneally at a dose of 12 nmol/kg 20 min before ghrelin injection. We mimicked the IIR process with hypoxia-reoxygenation (HR) in Caco-2 cells, which are similar to intestinal epithelial cells in structure and biochemistry. Our results showed that ghrelin inhibited IIR/HR-induced oxidative stress and apoptosis by activating GHSR-1α. Moreover, it was found that ghrelin activated the GHSR-1α/Sirt1/FOXO1 signaling pathway. We further inhibited Sirt1 and found that Sirt1 was critical for ghrelin-mediated mitigation of IIR/HR injury. Overall, our data suggest that pretreatment with ghrelin reduces oxidative stress and apoptosis to attenuate IIR/HR injury by binding with GHSR-1α to further activate Sirt1.
Subject(s)
Apoptosis , Forkhead Box Protein O1 , Ghrelin , Mice, Inbred C57BL , Oxidative Stress , Receptors, Ghrelin , Reperfusion Injury , Sirtuin 1 , Ghrelin/pharmacology , Ghrelin/metabolism , Reperfusion Injury/metabolism , Reperfusion Injury/drug therapy , Sirtuin 1/metabolism , Animals , Mice , Receptors, Ghrelin/metabolism , Humans , Male , Forkhead Box Protein O1/metabolism , Apoptosis/drug effects , Oxidative Stress/drug effects , Signal Transduction/drug effects , Intestines/drug effects , Caco-2 CellsABSTRACT
Sestrins are metabolic regulators that respond to stress by reducing the levels of reactive oxygen species (ROS) and inhibiting the activity of target of rapamycin complex 1 (mTORC1). Previous research has demonstrated that Sestrin2 mitigates ischemia-reperfusion (IR) injury in the heart, liver, and kidneys. However, its specific role in intestinal ischemia-reperfusion (IIR) injury remains unclear. To elucidate the role of Sestrin2 in IIR injury, we conducted an experimental study using a C57BL/6J mouse model of IIR. We noticed an increase in the levels of Sestrin2 expression and indicators associated with ferroptosis. Our study revealed that manipulating Sestrin2 expression in Caco-2 cells through overexpression or knockdown resulted in a corresponding decrease or increase, respectively, in ferroptosis levels. Furthermore, our investigation revealed that Sestrin2 alleviated ferroptosis caused by IIR injury through the activation of the Keap1/Nrf2 signal pathway. This finding highlights the potential of Sestrin2 as a therapeutic target for alleviating IIR injury. These findings indicated that the modulation of Sestrin2 could be a promising strategy for managing prolonged IIR injury.
Subject(s)
Ferroptosis , Mesenteric Ischemia , Reperfusion Injury , Animals , Humans , Mice , Caco-2 Cells , Ferroptosis/genetics , Ischemia , Kelch-Like ECH-Associated Protein 1/genetics , Mechanistic Target of Rapamycin Complex 1 , Mice, Inbred C57BL , NF-E2-Related Factor 2/genetics , Reperfusion , Reperfusion Injury/genetics , Signal TransductionABSTRACT
Mitochondria release many damage-associated molecular patterns (DAMPs) when cells are damaged or stressed, with mitochondrial DNA (mtDNA) being. MtDNA activates innate immune responses and induces inflammation through the TLR-9, NLRP3 inflammasome, and cGAS-STING signaling pathways. Released inflammatory factors cause damage to intestinal barrier function. Many bacteria and endotoxins migrate to the circulatory system and lymphatic system, leading to systemic inflammatory response syndrome (SIRS) and even damaging the function of multiple organs throughout the body. This process may ultimately lead to multiple organ dysfunction syndrome (MODS). Recent studies have shown that various factors, such as the release of mtDNA and the massive infiltration of inflammatory factors, can cause intestinal ischemia/reperfusion (I/R) injury. This destroys intestinal barrier function, induces an inflammatory storm, leads to SIRS, increases the vulnerability of organs, and develops into MODS. Mitophagy eliminates dysfunctional mitochondria to maintain cellular homeostasis. This review discusses mtDNA release during the pathogenesis of intestinal I/R and summarizes methods for the prevention or treatment of intestinal I/R. We also discuss the effects of inflammation and increased intestinal barrier permeability on drugs.
