Rong Cai

Reperfusion, an essential therapeutic strategy for salvaging ischemic myocardium in ischemic heart disease, paradoxically exacerbates myocardial injury. Ferroptosis is a pivotal mechanism underlying myocardial ischemia-reperfusion injury (MIRI). Nrf2 can regulate ferroptosis, which could undergo SUMOylation at lysine 110 (K110) and was subsequently de-SUMOylated by Senp1. This study aimed to determine whether Nrf2 de-SUMOylation could mitigate MIRI by inhibiting myocardial ferroptosis. Nrf2 K110R mice, mimicking Nrf2 de-SUMOylation, were generated. Mice cardiac morphology and function were observed by hematoxylin-eosin staining (HE) and echocardiography under normal and MIRI conditions. Ferroptosis inhibitor liproxstatin-1 (Lip-1) was used to demonstrate ferroptosis participation in Nrf2 de-SUMOylation regulated MIRI. In vitro, SUMO1/sentrin-specific protease 1 Senp1 KO H9C2 cells were subjected to RSL₃-induced ferroptosis to explore underlying mechanism. Nrf2 K110R mice showed normal cardiac morphology and function at baseline. However, de-SUMOylation of Nrf2 alleviated myocardial ferroptosis, resulting in a reduction of MIRI severity in MIRI mice. The administration of Lip-1 attenuated the differences in MIRI between Nrf2 wild-type and K110R mice. Mechanistically, Nrf2 de-SUMOylation was associated with a reduction in Transferrin receptor (Tfr) expression level, thereby mitigating ferroptosis in cardiomyocytes. This study highlighted the role of Nrf2 SUMOylation in promoting ferroptosis during MIRI and identified Nrf2 de-SUMOylation as a potential therapeutic target for MIRI.

Solute carrier family 25 member A22 (SLC25A22) is a glutamate transporter in the inner mitochondrial membrane that is known to suppress ferroptosis in pancreatic ductal adenocarcinoma (PDAC). Sirtuin 3 (SIRT3) is the main mitochondrial deacetylase, and we previously demonstrated that targeting SIRT3 sensitized glioblastoma to ferroptosis by promoting mitophagy and inhibiting SLC7A11. The purpose of this study was to analyze the effect of SIRT3-mediated deacetylation of mitochondrial SLC25A22 on RAS-selective lethal 3 (RSL3)-induced ferroptosis in lung adenocarcinoma (LUAD). We found that the expression of SLC25A22 and SIRT3 had a high positive correlation and that their expression was greater in LUAD tissues than in adjacent tissues. The RSL3-induced ferroptosis of LUAD led to upregulation of SLC25A22 and SIRT3, and SIRT3 protected RSL3-induced LUAD from ferroptosis in vitro and in vivo. At the molecular level, SIRT3 bound with SLC25A22 and deacetylated this protein. Targeting SIRT3 enhanced the acetylation of SLC25A22, decreased its ubiquitination, and promoted 26S proteasome degradation in LUAD cells. Therefore, our results demonstrated that SIRT3 protected LUAD cells from RSL3-induced ferroptosis, and this effect is at least partially due to its deacetylation of SLC25A22, revealing that the SIRT3-SLC25A22 axis has an important role in regulating the ferroptosis of LUAD cells.

Ferroptosis, a regulated cell death modality, driven by iron-dependent lipid peroxidation, is intrinsically coupled with mitochondrial metabolic turbulence and redox dysregulation. While the mitochondrial sirtuin Sirtuin 3 (SIRT3) is canonically viewed as a master regulator of energy homeostasis, its defensive repertoire against ferroptosis extends far beyond the simplistic activation of antioxidant enzymes. In this review, we synthesize emerging evidence to construct an integrated “metabolic-structural” defense model orchestrated by SIRT3. We first delineate how SIRT3 functions as a metabolic rheostat, rewiring tricarboxylic acid (TCA) cycle flux via the deacetylation of isocitrate dehydrogenase 2 (IDH2) to sustain the nicotinamide adenine dinucleotide phosphate (NADPH)/glutathione (GSH) reservoir. Breaking away from the classical enzymatic paradigm, we highlight a novel non-enzymatic substrate regulatory mechanism where SIRT3 stabilizes the glutamate transporter SLC25A22 through specific deacetylation-ubiquitination crosstalk, thereby limiting ferroptotic susceptibility. Furthermore, we expand the SIRT3 signaling landscape by proposing a “SIRT3-nuclear factor erythroid 2-related factor 2 (Nrf2) deacetylation axis” that bridges mitochondrial stress signals to nuclear transcriptional defense, and by detailing its control over iron entry via the iron regulatory protein 1 (IRP1)-transferrin receptor 1 (TfR1) pathway. At the organelle level, we examine how SIRT3 remodels mitochondrial dynamics, upregulating optic atrophy-associated protein 1 (OPA1) while suppressing dynamin-related protein 1 (DRP1), to construct a “fusion network barrier” that dilutes ROS toxicity. We also posit a critical hypothesis: SIRT3 safeguards the integrity of mitochondria-associated endoplasmic reticulum membranes, preventing structural decoupling and calcium overload that triggers ferroptotic sensitization. Finally, we reconcile the context-dependent duality of SIRT3 in cancer and degenerative diseases, outlining future therapeutic strategies that leverage these multidimensional vulnerabilities.

Glioblastoma multiforme (GBM) is a highly malignant brain tumor, and glioblastoma stem cells (GSCs) are the primary cause of GBM heterogeneity, invasiveness, and resistance to therapy. Sirtuin 3 (SIRT3) is mainly localized in the mitochondrial matrix and plays an important role in maintaining GSC stemness through cooperative interaction with the chaperone protein tumor necrosis factor receptor-associated protein 1 (TRAP1) to modulate mitochondrial respiration and oxidative stress. The present study aimed to further elucidate the specific mechanisms by which SIRT3 influences GSC stemness, including whether SIRT3 serves as an autophagy substrate and the mechanism of SIRT3 degradation. We first found that SIRT3 is enriched in CD133⁺ GSCs. Further experiments revealed that in addition to promoting mitochondrial respiration and reducing oxidative stress, SIRT3 maintains GSC stemness by epigenetically regulating CD133 expression via succinate. More importantly, we found that SIRT3 is degraded through the autophagy–lysosome pathway during GSC differentiation into GBM bulk tumor cells. GSCs are highly dependent on glutamine for survival, and in these cells, we found that glutamine deprivation triggers autophagic SIRT3 degradation to restrict CD133 expression, thereby disrupting the stemness of GSCs. Together our results reveal a novel mechanism by which SIRT3 regulates GSC stemness. We propose that glutamine restriction to trigger autophagic SIRT3 degradation offers a strategy to eliminate GSCs, which combined with other treatment methods may overcome GBM resistance to therapy as well as relapse.

Glioblastoma (GBM) cells require large amounts of iron for tumor growth and progression, which makes these cells vulnerable to destruction via ferroptosis induction. Mitochondria are critical for iron metabolism and ferroptosis. Sirtuin-3 (SIRT3) is a deacetylase found in mitochondria that regulates mitochondrial quality and function. This study aimed to characterize SIRT3 expression and activity in GBM and investigate the potential therapeutic effects of targeting SIRT3 while also inducing ferroptosis in these cells. We first found that SIRT3 expression was higher in GBM tissues than in normal brain tissues and that SIRT3 protein expression was upregulated during RAS-selective lethal 3 (RSL3)-induced GBM cell ferroptosis. We then observed that inhibition of SIRT3 expression and activity in GBM cells sensitized GBM cells to RSL3-induced ferroptosis both in vitro and in vivo. Mechanistically, SIRT3 inhibition led to ferrous iron and ROS accumulation in the mitochondria, which triggered mitophagy. RNA-Sequencing analysis revealed that upon SIRT3 knockdown in GBM cells, the mitophagy pathway was upregulated and SLC7A11, a critical antagonist of ferroptosis via cellular import of cystine for glutathione (GSH) synthesis, was downregulated. Forced expression of SLC7A11 in GBM cells with SIRT3 knockdown restored cellular cystine uptake and consequently the cellular GSH level, thereby partially rescuing cell viability upon RSL3 treatment. Furthermore, in GBM cells, SIRT3 regulated SLC7A11 transcription through ATF4. Overall, our study results elucidated novel mechanisms underlying the ability of SIRT3 to protect GBM from ferroptosis and provided insight into a potential combinatorial approach of targeting SIRT3 and inducing ferroptosis for GBM treatment.

Atherosclerosis (AS) is a serious cardiovascular disease. One of its hallmarks is hyperlipidemia. Inhibiting the formation of macrophage foam cells is critical for alleviating AS. Transcription factor EB (TFEB) can limit the formation of macrophage foam cells by upregulating lysosomal activity. We examined whether TFEB SUMOylation is involved in this progress during AS. In this study, we investigated the role of TFEB SUMOylation in macrophages in AS using TFEB SUMOylation deficiency Ldlr^−/− (TFEB-KR: Ldlr^−/−) transgenic mice and TFEB-KR bone marrow-derived macrophages. We observed that TFEB-KR: Ldlr^−/− atherosclerotic mice had thinner plaques and macrophages with higher lysosomal activity when compared to WT: Ldlr^−/− mice. TFEB SUMOylation in macrophages decreased after oxidized low-density lipoprotein (OxLDL) treatment in vitro. Compared with wild type macrophages, TFEB-KR macrophages exhibited less lipid deposition after OxLDL treatment. Our study demonstrated that in AS, deSUMOylation of TFEB could inhibit the formation of macrophage foam cells through enhancing lysosomal biogenesis and autophagy, further reducing the accumulation of lipids in macrophages, and ultimately alleviating the development of AS. Thus, TFEB SUMOylation can be a switch to modulate macrophage foam cells formation and used as a potential target for AS therapy.

Lung adenocarcinoma (LUAD) is the most common lung cancer, which accounts for about 35–40% of all lung cancer patients. Despite therapeutic advancements in recent years, the overall survival time of LUAD patients still remains poor, especially KRAS mutant LUAD. Therefore, it is necessary to further explore novel targets and drugs to improve the prognos is for LUAD. Ferroptosis, an iron-dependent regulated cell death (RCD) caused by lipid peroxidation, has attracted much attention recently as an alternative target for apoptosis in LUAD therapy. Ferroptosis has been found to be closely related to LUAD at every stage, including initiation, proliferation, and progression. In this review, we will provide a comprehensive overview of ferroptosis mechanisms, its regulation in LUAD, and the application of targeting ferroptosis for LUAD therapy.

Glioblastoma (GBM) cells require large amounts of iron for tumor growth and progression, which makes these cells vulnerable to destruction via ferroptosis induction. Mitochondria are critical for iron metabolism and ferroptosis. Sirtuin-3 (SIRT3) is a deacetylase found in mitochondria that regulates mitochondrial quality and function. This study aimed to characterize SIRT3 expression and activity in GBM and investigate the potential therapeutic effects of targeting SIRT3 while also inducing ferroptosis in these cells. We first found that SIRT3 expression was higher in GBM tissues than in normal brain tissues and that SIRT3 protein expression was upregulated during RAS-selective lethal 3 (RSL3)-induced GBM cell ferroptosis. We then observed that inhibition of SIRT3 expression and activity in GBM cells sensitized GBM cells to RSL3-induced ferroptosis both in vitro and in vivo. Mechanistically, SIRT3 inhibition led to ferrous iron and ROS accumulation in the mitochondria, which triggered mitophagy. RNA-Sequencing analysis revealed that upon SIRT3 knockdown in GBM cells, the mitophagy pathway was upregulated and SLC7A11, a critical antagonist of ferroptosis via cellular import of cystine for glutathione (GSH) synthesis, was downregulated. Forced expression of SLC7A11 in GBM cells with SIRT3 knockdown restored cellular cystine uptake and consequently the cellular GSH level, thereby partially rescuing cell viability upon RSL3 treatment. Furthermore, in GBM cells, SIRT3 regulated SLC7A11 transcription through ATF4. Overall, our study results elucidated novel mechanisms underlying the ability of SIRT3 to protect GBM from ferroptosis and provided insight into a potential combinatorial approach of targeting SIRT3 and inducing ferroptosis for GBM treatment.

Lung adenocarcinoma (LUAD) is the most common lung cancers, which accounts for about 35%-40% of all lung cancer patients. Despite therapeutic advancements in recent years, the overall survival time of the LUAD patients still remain poor, especially KRAS mutant LUAD. Therefore, it is necessary to further explore novel targets and drugs to improve the prognosis of LUAD. Ferroptosis, an iron-dependent regulated cell death (RCD）caused by lipid peroxidation, has attracted much attention recently as an alternative target for apoptosis in LUAD therapy. Ferroptosis has been found closely related with LUAD, at its every stage, including initiation, proliferation and progression. In this review, we will provide a comprehensive overview on ferroptosis mechanisms, it’s regulation in LUAD, and application of targeting ferroptosis for LUAD therapy.