Knockdown Of Heme Oxygenase-1 Research Articles

A Mechanistic Study of the Osteogenic Effect of Arecoline in an Osteoporosis Model: Inhibition of Iron Overload-Induced Osteogenesis by Promoting Heme Oxygenase-1 Expression.

Iron overload-associated osteoporosis presents a significant challenge to bone health. This study examines the effects of arecoline (ACL), an alkaloid found in areca nut, on bone metabolism under iron overload conditions induced by ferric ammonium citrate (FAC) treatment. The results indicate that ACL mitigates the FAC-induced inhibition of osteogenesis in zebrafish larvae, as demonstrated by increased skeletal mineralization and upregulation of osteogenic genes. ACL attenuates FAC-mediated suppression of osteoblast differentiation and mineralization in MC3T3-E1 cells. RNA sequencing analysis suggests that the protective effects of ACL are related to the regulation of ferroptosis. We demonstrate that ACL inhibits ferroptosis, including oxidative stress, lipid peroxidation, mitochondrial damage, and cell death under FAC exposure. In this study, we have identified heme oxygenase-1 (HO-1) as a critical mediator of ACL inhibiting ferroptosis and promoting osteogenesis, which was validated by HO-1 knockdown and knockout experiments. The study links ACL to HO-1 activation and ferroptosis regulation in the context of bone metabolism. These findings provide new insights into the mechanisms underlying the modulation of osteogenesis by ACL. Targeting the HO-1/ferroptosis axis is a promising therapeutic approach for treating iron overload-induced bone diseases.

Absence of Heme Oxygenase-1 Affects Trophoblastic Spheroid Implantation and Provokes Dysregulation of Stress and Angiogenesis Gene Expression in the Uterus.

The enzyme heme oxygenase-1 (HO-1) is pivotal in reproductive processes, particularly in placental and vascular development. This study investigated the role of HO-1 and its byproduct, carbon monoxide (CO), in trophoblastic spheroid implantation. In order to deepen our understanding of the role of HO-1 during implantation, we conducted in vivo experiments on virgin and pregnant mice, aiming to unravel the cellular and molecular mechanisms. Using siRNA, HO-1 was knocked down in JEG-3 and BeWo cells and trophoblastic spheroids were generated with or without CO treatment. Adhesion assays were performed after transferring the spheroids to RL-95 endometrial epithelial cell layers. Additionally, angiogenesis, stress, and toxicity RT2-Profiler™ PCR SuperArray and PCR analyses were performed in uterine murine samples. HO-1 knockdown by siRNA impeded implantation in the 3D culture model, but this effect could be reversed by CO. Uteruses from virgin Hmox1-/- females exhibited altered expression of angiogenesis and stress markers. Furthermore, there was a distinct expression pattern of cytokines and chemokines in uteruses from gestation day 14 in Hmox1-/- females compared to Hmox1+/+ females. This study strongly supports the essential role of HO-1 during implantation. Moreover, CO appears to have the potential to compensate for the lack of HO-1 during the spheroid attachment process. The absence of HO-1 results in dysregulation of angiogenesis and stress-related genes in the uterus, possibly contributing to implantation failure.

Wogonin inhibits oxidative stress and vascular calcification via modulation of heme oxygenase-1

Vascular calcification (VC) is highly prevalent and increases the morbidity and mortality of cardiovascular diseases. However, the underlying mechanism remains unclear and there is no effective treatment so far. Interestingly, using systems pharmacology approach, we have predicted that Wogonin (Wog) exhibited potential activity against VC. Then we validated the effect of Wog on VC using human and rat vascular smooth muscle cells (VSMCs), rat arterial rings and vitamin D3-overloaded mouse models. Our results showed that Wog dose-dependently inhibited calcification of VSMCs and rat arterial rings. Consistently, alizarin red staining and calcium content assay confirmed that Wog inhibited aortic calcification in vitamin D3-overloaded mice. Moreover, by constructing the protein regulating network of Wog in suppressing VC, we found heme oxygenase-1 (HMOX-1) was regulated by Wog. Additionally, pathway enrichment analysis revealed that inhibition of reactive oxygen species (ROS) pathway participated in the inhibitory role of Wog in VC and HMOX-1 was also involved in this process. Notably, our study revealed that Wog treatment promoted HMOX-1 expression, and reduced ROS levels in VSMCs. Interestingly, both inhibition of HMOX-1 by ZnPP9 and knockdown of HMOX-1 by siRNA independently eliminated the inhibitory effect of Wog on VC. Finally, administration of Wog suppressed aortic calcification in vitamin D3-overloaded mice and this effect was counteracted by ZnPP9,suggesting the crucial role of HMOX-1 in the inhibitory effect of Wog on VC. Collectively, this study combines systems pharmacology-based strategy and experiments to identify the therapeutic potential of Wog for VC via upregulating HMOX-1 and reducing oxidative stress.

Three-dimensional growth sensitizes breast cancer cells to treatment with ferroptosis-promoting drugs

Drugs causing ferroptosis, iron-mediated cell death, represent promising tools for cancer treatment. While exploring the effect of these drugs on breast cancer (BC), we found that a ferroptosis-inducing drug erastin dramatically inhibits tumorigenicity of human BC cells in mice but when used at a concentration known to effectively kill other cell types only modestly reduces such growth in 2D monolayer culture. BCs grow in vivo as 3D masses, and we found that ferroptosis inducers erastin and sulfasalazine inhibit growth of multiple human BC cell lines in 3D culture significantly stronger than in 2D culture. To understand the mechanism of this differential effect, we found that ferroptosis inducers upregulate mRNAs encoding multiple direct and indirect autophagy stimulators, such as ATG16L2, ATG9A, ATG4D, GABARAP, SQSTM/p62, SEC23A and BAX, in tumor cells growing in 2D but not in 3D culture. Furthermore, these drugs promoted autophagy of tumor cells growing in a 2D but not in a 3D manner. We observed that pharmacological inhibition of autophagy-stimulating protein kinase ULK1 or RNA interference-mediated knockdown of autophagy mediator ATG12 significantly sensitized tumor cells to erastin treatment in 2D culture. We also found that ferroptosis-promoting treatments upregulate heme oxygenase-1 (HO-1) in BC cells. HO-1 increases cellular free iron pool and can potentially promote ferroptosis. Indeed, we observed that HO-1 knockdown by RNA interference reversed the effect of ferroptosis inducers on BC cell 3D growth. Hence, the effect of these drugs on such growth is mediated by HO-1. In summary, autophagy triggered by ferroptosis-promoting drugs reduces their ability to kill BC growing in a 2D manner. This protection mechanism is inhibited in BC cells growing as a 3D mass, and ferroptosis-promoting drugs kill such cells more effectively. Moreover, this death is mediated by HO-1. Thus, ferroptosis induction represents a promising strategy for blocking 3D BC growth.

A Novel Derivative of Curcumol, HCL-23, Inhibits the Malignant Phenotype of Triple-Negative Breast Cancer and Induces Apoptosis and HO-1-Dependent Ferroptosis.

Triple-negative breast cancer (TNBC) is the most aggressive molecular subtype of breast cancer. Curcumol, as a natural small molecule compound, has potential anti-breast cancer activity. In this study, we chemically synthesized a derivative of curcumol, named HCL-23, by structural modification and explored its effect on and underlying mechanism regarding TNBC progression. MTT and colony formation assays demonstrated that HCL-23 significantly inhibited TNBC cells proliferation. HCL-23 induced G2/M phase cell cycle arrest and repressed the capability of migration, invasion, and adhesion in MDA-MB-231 cells. RNA-seq results identified 990 differentially expressed genes including 366 upregulated and 624 downregulated genes. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) revealed that these differentially expressed genes were obviously enriched in adhesion, cell migration, apoptosis, and ferroptosis. Furthermore, HCL-23 induced apoptosis via the loss of mitochondrial membrane potential and the activation of the caspase family in TNBC cells. In addition, HCL-23 was verified to trigger ferroptosis through increasing cellular reactive oxygen species (ROS), labile iron pool (LIP), and lipid peroxidation levels. Mechanistically, HCL-23 markedly upregulated the expression of heme oxygenase 1 (HO-1), and the knockdown of HO-1 could attenuate ferroptosis induced by HCL-23. In animal experiments, we found that HCL-23 inhibited tumor growth and weight. Consistently, the upregulation of Cleaved Caspase-3, Cleaved PARP, and HO-1 expression was also observed in tumor tissues treated with HCL-23. In summary, the above results suggest that HCL-23 can promote cell death through activating caspases-mediated apoptosis and HO-1-dependent ferroptosis in TNBC. Therefore, our findings provide a new potential agent against TNBC.

Heme oxygenase-1 ameliorates endotoxin-induced acute lung injury by modulating macrophage polarization via inhibiting TXNIP/NLRP3 inflammasome activation.

Acute lung injury (ALI) remains a global public health issue without specific and effective treatment options available in the clinic. Alveolar macrophage polarization is involved in the initiation, development and progression of ALI; however, the underlying mechanism remains poorly understood. Heme oxygenase-1 (HO-1) acts as an antioxidant in pulmonary inflammation and has been demonstrated to be linked with the severity and prognosis of ALI. In this study, the therapeutic effects of HO-1 were examined, along with the mechanisms involved, mainly focusing on alveolar macrophage polarization. HO-1 depletion induced higher iNOS and CD86 (M1 phenotype) expression but was significantly decreased in Arg-1 and CD206 (M2 phenotype) expression in BALF alveolar macrophages after equivalent LPS stimulation. We also found that HO-1 deletion distinctly accelerated the expression of inflammasome-associated components NLRP3, ASC and caspase-1 in vivo and in vivo and in vitro. Moreover, on the basis of LPS for MH-S cells, levels of TXNIP, NLRP3, ASC and caspase-1 were increased and HO-1 depletion exacerbated these changes, whereas double depletion of HO-1 and TXNIP partially mitigated these elevations. Also, HO-1 knockdown induced more M1 phenotype and less M2 phenotype compared with LPS alone, whereas double silence of HO-1 and TXNIP partially changed the polarization state. Taken together, we demonstrated that HO-1 could modulate macrophage polarization via TXNIP/NLRP3 signaling pathway, which could be a potential therapeutic target for ALI treatment.

Dynamics of antioxidant heme oxygenase-1 and pro-oxidant p66Shc in promoting advanced prostate cancer progression.

The castration-resistant (CR) prostate cancer (PCa) is lethal and is the second leading cause of cancer-related deaths in U.S. males. To develop effective treatments toward CR PCa, we investigated reactive oxygen species (ROS) signaling pathway for its role involving in CR PCa progression. ROS can regulate both cell growth and apoptosis: a moderate increase of ROS promotes proliferation; its substantial rise results in cell death. p66Shc protein can increase oxidant species production and its elevated level is associated with the androgen-independent (AI) phenotype of CR PCa cells; while heme oxygenase-1 (HO-1) is an antioxidant enzyme and elevated in a sub-group of metastatic PCa cells. In this study, our data revealed that HO-1 and p66Shc protein levels are co-elevated in various AI PCa cell lines as well as p66Shc cDNA-transfected cells. Knockdown and/or inhibition of either p66Shc or HO-1 protein leads to reduced tumorigenicity as well as a reduction of counterpart protein. Knockdown of HO-1 alone results in increased ROS levels, nucleotide and protein oxidation and induction of cell death. Together, our data indicate that elevated HO-1 protein levels protect PCa cells from otherwise apoptotic conditions induced by aberrant p66Shc/ROS production, which thereby promotes PCa progression to the CR phenotype. p66Shc and HO-1 can serve as functional targets for treating CR PCa.

Dendrobium officinale polysaccharide inhibits vascular calcification via anti-inflammatory and anti-apoptotic effects in chronic kidney disease.

Vascular calcification is very common in patients with chronic kidney disease (CKD), but so far, there is no effective treatment. Dendrobium officinale polysaccharide (DOP), a natural component of Chinese herbal medicine, has been shown to exert anti-inflammatory and anti-apoptotic activity. Inflammation and apoptosis play an essential role in the progression of vascular calcification. However, the exact role and molecular mechanisms of DOP in vascular calcification remain unclear. In this study, we investigated the effects of DOP on vascular calcification using vascular smooth muscle cells (VSMCs), arterial rings, and CKD rats. Alizarin red staining and gene expression analysis revealed that DOP inhibited calcification and osteogenic differentiation of rat VSMCs in a dose-dependent manner. Similarly, ex vivo studies revealed that DOP inhibited the calcification of rat arterial rings. Furthermore, the administration of DOP alleviated vascular calcification in CKD rats. Moreover, DOP treatment suppressed VSMC inflammation and apoptosis. Finally, DOP treatment upregulated mRNA and protein levels of heme oxygenase-1 (HMOX-1); both pharmacological inhibition of HMOX-1 by the HMOX-1 inhibitor zinc protoporphyrin-9ZnPP9 and knockdown of HMOX-1 by siRNA markedly abrogated the suppression of inflammation and osteogenic differentiation of VSMCs by DOP. Collectively, these results suggest that DOP alleviates vascular calcification in CKD by suppressing apoptosis and inflammation via HMOX-1 activation. These results may provide a promising treatment for vascular calcification in CKD.

Canagliflozin Inhibits Human Endothelial Cell Inflammation through the Induction of Heme Oxygenase-1.

Sodium-glucose co-transporter 2 (SGLT2) inhibitors improve cardiovascular outcomes in patients with type 2 diabetes mellitus (T2DM). Studies have also shown that canagliflozin directly acts on endothelial cells (ECs). Since heme oxygenase-1 (HO-1) is an established modulator of EC function, we investigated if canagliflozin regulates the endothelial expression of HO-1, and if this enzyme influences the biological actions of canagliflozin in these cells. Treatment of human ECs with canagliflozin stimulated a concentration- and time-dependent increase in HO-1 that was associated with a significant increase in HO activity. Canagliflozin also evoked a concentration-dependent blockade of EC proliferation, DNA synthesis, and migration that was unaffected by inhibition of HO-1 activity and/or expression. Exposure of ECs to a diabetic environment increased the adhesion of monocytes to ECs, and this was attenuated by canagliflozin. Knockdown of HO-1 reduced the anti-inflammatory effect of canagliflozin which was restored by bilirubin but not carbon monoxide. In conclusion, this study identified canagliflozin as a novel inducer of HO-1 in human ECs. It also found that HO-1-derived bilirubin contributed to the anti-inflammatory action of canagliflozin, but not the anti-proliferative and antimigratory effects of the drug. The ability of canagliflozin to regulate HO-1 expression and EC function may contribute to the clinical profile of the drug.

Eriodictyol Attenuates Cholangiocarcinoma Malignancy by Regulating HMOX1 Expression: An In Vitro Study.

Cholangiocarcinoma remains one of the most dangerous types of cancer. Eriodictyol is a well-known flavonoid having effective bioactivity against various malignant tumor types. However, the anticancer effect of eriodictyol against cholangiocarcinoma remains ambiguous. Thus, the aim of the present study was to investigate the effects of eriodictyol on human cholangiocarcinoma. The biological effects of eriodictyol were validated by viability assay, colony formation and western blot analysis. The significance of heme oxygenase 1 (HMOX1) expression in cholangio-carcinoma was demonstrated using bioinformatics analysis and knockdown of HMOX1 by transfection with short interfering (si)-RNA. Eriodictyol highly reduced the in vitro viability of SNU-308, SNU-478, SNU-1079, and SNU-1196 cholangiocarcinoma cells compared with that of 293T cells, in a dose-dependent manner. The anticancer effect of eriodictyol was achieved by caspase-3-mediated apoptosis. In particular, eriodictyol increased HMOX1 expression, which resulted in attenuation of cholangiocarcinoma cell proliferation. In contrast, ablating HMOX1 expression by si-RNA transfection against HMOX1 made cholangiocarcinoma cells insensitive to the antiproliferative effect of eriodictyol treatment. These results collectively indicate that eriodictyol acts as an anticancer agent via regulation of HMOX1 expression against human cholangiocarcinoma.

LncRNA UCA1 promoted cisplatin resistance in lung adenocarcinoma with HO1 targets NRF2/HO1 pathway.

Our previous experiments have demonstrated that lncRNA UCA1 (UCA1) promoted cisplatin resistance in lung adenocarcinoma (LUAD). This study aimed to explore the potential downstream target genes regulated by UCA1 and how this downstream gene promotes cisplatin resistance in LUAD. Here, we measured the expression level of Heme oxygenase1 (HO1) in LUAD cell lines by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) based on UCA1 overexpression cell lines and UCA1 knockdown cell lines. HO1 was knocked down in the UCA1 overexpression cell line, and HO1 was overexpressed in the UCA1 knockdown cell line, and the half maximal inhibitory concentration (IC50) trends were observed by adding cisplatin containing a certain concentration gradient. Cell functional assays were performed to observe the changes in the biological behavior of HO1 after overexpression and knockdown, and the tumorigenic assay in nude mice was performed to verify the effect of UCA1 in regulating the growth and cisplatin resistance of HO1 on LUAD cells in vivo. The results showed that HO1 and UCA1 expression were both upregulated in LUAD tissues and LUAD cisplatin-resistant cell lines, and there was a significant positive correlation between the expression of HO1 and UCA1. In vitro experiments showed that HO1 overexpression could reverse the reduced sensitivity to cisplatin caused by UCA1 knockdown in A549/DDP cells, and HO1 knockdown could reduce cisplatin resistance in A549 UCA1 overexpressing cells. Tumorigenic assays in nude mice further confirmed the role of HO1 in the regulation of UCA1 by activating the NRF2/HO1 pathway against LUAD cisplatin resistance. Our findings suggested that UCA1 regulates HO1 targets the UCA1/NRF2-HO1 pathway to exert cisplatin resistance in LUAD.

Targeting the NRF2/HO-1 Antioxidant Pathway in FLT3-ITD-Positive AML Enhances Therapy Efficacy.

Acute myeloid leukemia (AML) is a molecularly heterogenous hematological malignancy, with one of the most common mutations being internal tandem duplication (ITD) of the juxtamembrane domain of the fms-like tyrosine kinase receptor-3 (FLT3). Despite the development of FLT3-directed tyrosine kinase inhibitors (TKI), relapse and resistance are problematic, requiring improved strategies. In both patient samples and cell lines, FLT3-ITD raises levels of reactive oxygen species (ROS) and elicits an antioxidant response which is linked to chemoresistance broadly in AML. NF-E2–related factor 2 (NRF2) is a transcription factor regulating the antioxidant response including heme oxygenase -1 (HO-1), a heat shock protein implicated in AML resistance. Here, we demonstrate that HO-1 is elevated in FLT3-ITD-bearing cells compared to FLT3-wild type (WT). Transient knockdown or inhibitor-based suppression of HO-1 enhances vulnerability to the TKI, quizartinib, in both TKI-resistant and sensitive primary AML and cell line models. NRF2 suppression (genetically or pharmacologically using brusatol) results in decreased HO-1, suggesting that TKI-resistance is dependent on an active NRF2-driven pathway. In AML-patient derived xenograft (PDX) models, brusatol, in combination with daunorubicin, reduces leukemia burden and prolongs survival. Cumulatively, these data encourage further development of brusatol and NRF2 inhibition as components of combination therapy for refractory AML.

Celastrol induces ferroptosis in activated HSCs to ameliorate hepatic fibrosis via targeting peroxiredoxins and HO-1

Ferroptosis is a form of regulated cell death, characterized by excessive membrane lipid peroxidation in an iron- and ROS-dependent manner. Celastrol, a natural bioactive triterpenoid extracted from Tripterygium wilfordii, shows effective anti-fibrotic and anti-inflammatory activities in multiple hepatic diseases. However, the exact molecular mechanisms of action and the direct protein targets of celastrol in the treatment of liver fibrosis remain largely elusive. Here, we discover that celastrol exerts anti-fibrotic effects via promoting the production of reactive oxygen species (ROS) and inducing ferroptosis in activated hepatic stellate cells (HSCs). By using activity-based protein profiling (ABPP) in combination with bio-orthogonal click chemistry reaction and cellular thermal shift assay (CETSA), we show that celastrol directly binds to peroxiredoxins (PRDXs), including PRDX1, PRDX2, PRDX4 and PRDX6, through the active cysteine sites, and inhibits their anti-oxidant activities. Celastrol also targets to heme oxygenase 1 (HO-1) and upregulates its expression in activated-HSCs. Knockdown of PRDX1, PRDX2, PRDX4, PRDX6 or HO-1 in HSCs, to varying extent, elevated cellular ROS levels and induced ferroptosis. Taken together, our findings reveal the direct protein targets and molecular mechanisms via which celastrol ameliorates hepatic fibrosis, thus supporting the further development of celastrol as a promising therapeutic agent for liver fibrosis.

1,25-Dihydroxyvitamin D3 attenuates IL-1β secretion by suppressing NLRP1 inflammasome activation by upregulating the NRF2-HO-1 pathway in epidermal keratinocytes

The nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein (NLRP) inflammasome is a key inflammatory signaling pathway activated via a two-step signaling process consisting of priming and activation steps. Several studies have shown that 1,25-dihydroxyvitamin D3 (1,25(OH)2VD3) inhibits the priming step required for NLRP3 inflammasome activation in immune cells. However, as activating the NLRP1 inflammasome in keratinocytes does not necessarily require a priming step, whether 1,25(OH)2VD3 inhibits NLRP1 activation in unprimed keratinocytes is currently unknown. In this study, we showed that 1,25(OH)2VD3 inhibits nigericin-induced NLRP1 inflammasome activation in unprimed keratinocytes. 1,25(OH)2VD3 suppressed nigericin-induced interleukin-1β (IL-1β) secretion and caspase-1 activation in human primary keratinocytes. In addition, 1,25(OH)2VD3 significantly inhibited the formation of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) oligomers and specks, but not caspase-1 enzymatic activity, suggesting that 1,25(OH)2VD3 prevents NLRP1-ASC complex assembly in keratinocytes. Vitamin D receptor (VDR)-knockdown abolished the inhibitory effects of 1,25(OH)2VD3 on nigericin-induced ASC oligomerization and IL-1β secretion, suggesting that 1,25(OH)2VD3 suppresses inflammasome activation via VDR signaling. Furthermore, nigericin induced K+ efflux and cellular reactive oxygen species (ROS) production, and 1,25(OH)2VD3 pretreatment suppressed nigericin-induced ROS production. 1,25(OH)2VD3 increased the expression of both nuclear factor erythroid 2-related factor 2 (NRF2) and heme oxygenase-1 (HO-1), whereas HO-1 inhibition or NRF2 and HO-1 knockdown abrogated the inhibitory effects of 1,25(OH)2VD3 on IL-1β secretion. Our results indicate that 1,25(OH)2VD3 inhibits nigericin-induced activation step of NLRP1 inflammasome activation in unprimed keratinocytes. Our findings reveal the mechanism underlying the inhibitory effect of 1,25(OH)2VD3, which involves NRF2-HO-1 pathway activation through the VDR, providing further insight into the potential function of 1,25(OH)2VD3 as a therapeutic agent for inflammasome-related skin diseases.

HO‑1 knockdown upregulates the expression of VCAM‑1 to induce neutrophil recruitment during renal ischemia‑reperfusion injury.

Heme oxygenase-1 (HO-1) has been reported to be upregulated following renal ischemia-reperfusion injury (IRI) and plays a key cytoprotective role; however, the underlying molecular mechanisms of its protective effects remain poorly understood. In the present study, in order to further elucidate the molecular mechanisms underlying the cytoprotective role of HO-1 in renal IRI, HO-1+/+ and HO-1+/− mice were subjected to renal ischemia and subsequent reperfusion followed by the analysis of blood urea nitrogen (BUN) and serum creatinine (SCr) levels, the severity of histological changes, HO-1 and vascular cell adhesion molecule-1 (VCAM-1) protein expression, the mRNA expression of inflammatory factors and the effects of VCAM-1 blockade. The results of the present study demonstrated that the upregulated expression levels of VCAM-1 in HO-1+/− mice during IRI increased the extent of renal tissue damage and activated the inflammatory response. These effects were subsequently reversed following infusion with an anti-VCAM-1 antibody. In addition, the upregulated expression of VCAM-1 in mouse glomerulus vascular endothelial cells isolated from HO-1+/− mice increased the adhesion and migration of neutrophils, effects which were also reversed upon incubation with an anti-VCAM-1 antibody. These results indicated that HO-1 knockdown may upregulate the expression of VCAM-1 during renal IRI, resulting in increased neutrophil recruitment and the activation of the inflammatory response, thereby exacerbating renal IRI. The present study thus highlights the regulatory mechanisms of HO-1 in renal IRI and provides a potential target for the clinical treatment of IRI following renal transplantation.

HO-1 nuclear accumulation and interaction with NPM1 protect against stress-induced endothelial senescence independent of its enzymatic activity

Heme oxygenase-1 (HO-1) has attracted accumulating attention for its antioxidant enzymatic activity. However, the exact regulatory role of its non-enzymatic activity in the cardiovascular system remains unaddressed. Here, we show that HO-1 was accumulated in the nuclei of stress-induced senescent endothelial cells, and conferred protection against endothelial senescence independent of its enzymatic activity. Overexpression of ΔHO-1, a truncated HO-1 without transmembrane segment (TMS), inhibited H2O2-induced endothelial senescence. Overexpression of ΔHO-1H25A, the catalytically inactive form of ΔHO-1, also exhibited anti-senescent effect. In addition, infection of recombinant adenovirus encoding ΔHO-1 with three nuclear localization sequences (NLS), alleviated endothelial senescence induced by knockdown of endogenous HO-1 by CRISPR/Cas9. Moreover, repression of HO-1 nuclear translocation by silencing of signal peptide peptidase (SPP), which is responsible for enzymatic cleavage of the TMS of HO-1, exacerbated endothelial senescence. Mechanistically, nuclear HO-1 interacted with NPM1 N-terminal portion, prevented NPM1 translocation from nucleolus to nucleoplasm, thus disrupted NPM1/p53/MDM2 interactions and inhibited p53 activation by NPM1, finally resisted endothelial senescence. This study provides a novel understanding of HO-1 as a promising therapeutic strategy for vascular senescence-related cardiovascular diseases.

Fluid shear stress regulates placental growth factor expression via heme oxygenase 1 and iron

Increased fluid shear stress (FSS) is a key initiating stimulus for arteriogenesis, the outward remodeling of collateral arterioles in response to upstream occlusion. Placental growth factor (PLGF) is an important arteriogenic mediator. We previously showed that elevated FSS increases PLGF in a reactive oxygen species (ROS)-dependent fashion both in vitro and ex vivo. Heme oxygenase 1 (HO-1) is a cytoprotective enzyme that is upregulated by stress and has arteriogenic effects. In the current study, we used isolated murine mesentery arterioles and co-cultures of human coronary artery endothelial cells (EC) and smooth muscle cells (SMC) to test the hypothesis that HO-1 mediates the effects of FSS on PLGF. HO-1 mRNA was increased by conditions of increased flow and shear stress in both co-cultures and vessels. Both inhibition of HO-1 with zinc protoporphyrin and HO-1 knockdown abolished the effect of FSS on PLGF. Conversely, induction of HO-1 activity increased PLGF. To determine which HO-1 product upregulates PLGF, co-cultures were treated with a CO donor (CORM-A1), biliverdin, ferric ammonium citrate (FAC), or iron-nitrilotriacetic acid (iron-NTA). Of these FAC and iron-NTA induced an increase PLGF expression. This study demonstrates that FSS acts through iron to induce pro-arteriogenic PLGF, suggesting iron supplementation as a novel potential treatment for revascularization.

Dynamic and Temporal Transcriptomic Analysis Reveals Ferroptosis-Mediated Antileukemia Activity of S-Dimethylarsino-Glutathione: Insights into Novel Therapeutic Strategy

Dynamic and Temporal Transcriptomic Analysis Reveals Ferroptosis-Mediated Antileukemia Activity of S-Dimethylarsino-Glutathione: Insights into Novel Therapeutic Strategy

HO-1-mediated ferroptosis as a target for protection against retinal pigment epithelium degeneration

Oxidative stress-mediated retinal pigment epithelium (RPE) degeneration plays a vital role in retinal degeneration with irreversible visual impairment, most notably in age-related macular degeneration (AMD), but a key pathogenic factor and the targeted medical control remain controversial and unclear. In this work, by sophisticated high-throughput sequencing and biochemistry investigations, the major pathologic processes during RPE degeneration in the sodium iodate-induced oxidative stress model has been identified to be heme oxygenase-1 (HO-1)-regulated ferroptosis, which is controlled by the Nrf2–SLC7A11–HO-1 hierarchy, through which ferrous ion accumulation and lethal oxidative stress cause RPE death and subsequently photoreceptor degeneration. By direct knockdown of HO-1 or using HO-1 inhibitor ZnPP, the specific inhibition of HO-1 overexpression has been determined to significantly block RPE ferroptosis. In mice, treatment with ZnPP effectively rescued RPE degeneration and achieved superior therapeutic effects: substantial recovery of the retinal structure and visual function. These findings highlight that targeting HO-1-mediated RPE ferroptosis could serve as an effectively retinal-protective strategy for retinal degenerative diseases prevention, including AMD.

Differentiation of Hodgkin lymphoma cells by reactive oxygen species and regulation by heme oxygenase-1 through HIF-1α.

We previously indicated that Hodgkin lymphoma (HL) cells contain a small side population (SP) that differentiate into a large major population (MP) with giant Hodgkin and Reed‐Sternberg (H and RS)‐like cells. However, its molecular mechanisms are not fully understood. In this study, we found that intracellular reactive oxygen species (ROS) are low in the SP compared to the MP. Hydrogen peroxide induces large H‐ and RS‐like cells in HL cell lines, but induces cell death in unrelated lymphoid cell lines. Microarray analyses revealed the enrichment of upregulated genes under hypoxic conditions in the SP compared to the MP, and we verified that the SP cells are hypoxic. Hypoxia inducible factor (HIF)‐1α was preferentially expressed in the SP. CoCl2, a HIF‐1α stabilizer, blunted the effect of hydrogen peroxide. Heme oxygenase‐1 (HO‐1), a scavenger of ROS, was triggered by HIF‐1α. The effect of hydrogen peroxide was inhibited by HO‐1 induction, whereas it was promoted by HO‐1 knockdown. HO‐1 inhibition by zinc protoporphyrin promoted the differentiation and increased ROS. These results stress the unique roles of ROS in the differentiation of HL cells. Immature HL cells are inhibited from differentiation by a reduction of ROS through the induction of HO‐1 via HIF‐1α. The breakdown of this might cause the accumulation of intracellular ROS, resulting in the promotion of HL cell differentiation.