Sonic hedgehog signaling facilitates pyroptosis in mouse heart following ischemia/reperfusion via enhancing the formation of CARD10-BCL10-MALT1 complex.

Pyroptosis has been found to contribute to myocardial ischemia/reperfusion (I/R) injury, but the exact mechanisms that initiate myocardial pyroptosis are not fully elucidated. Sonic hedgehog (SHH) signaling is activated in heart suffered I/R, and intervention of SHH signaling has been demonstrated to protect heart from I/R injury. Caspase recruitment domain-containing protein 10 (CARD10)-B cell lymphoma 10 (BCL10)-mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) (CBM) complex could transduce signals from the membrane and induce inflammatory pathways in non-hematopoietic cells, which could be a downstream effector of SHH signaling pathway. This study aims to explore the role of SHH signaling in I/R-induced myocardial pyroptosis and its relationship with the CBM complex. C57BL/6J mice were subjected to 45 min-ischemia followed by 24 h-reperfusion to establish a myocardial I/R model, and H9c2 cells underwent hypoxia/reoxygenation (H/R) to mimic myocardial I/R model in vitro. Firstly, SHH signaling was significantly activated in heart suffered I/R in an autocrine- or paracrine-dependent manner via its receptor PTCH1, and inhibition of SHH signaling decreased myocardial injury via reducing caspase-11-dependent pyroptosis, concomitant with attenuating CBM complex formation. Secondly, suppression of SHH signaling decreased protein kinase C α (PKCα) level, but inhibition of PKCα attenuated CBM complex formation without impacting the protein levels of SHH and PTCH1. Finally, disruption of the CBM complex prevented MALT1 from recruiting of TRAF6, which was believed to trigger the caspase-11-dependent pyroptosis. Based on these results, we conclude that inhibition of SHH signaling suppresses pyroptosis via attenuating PKCα-mediated CARD10-BCL10-MALT1 complex formation in mouse heart suffered I/R.

Micafungin protects mouse heart against doxorubicin-induced oxidative injury via suppressing MALT1-dependent k48-linked ubiquitination of Nrf2.

Oxidative stress contributes greatly to doxorubicin (DOX)-induced cardiotoxicity. Down-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) is a key factor in DOX-induced myocardial oxidative injury. Recently, we found that mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1)-dependent k48-linked ubiquitination was responsible for down-regulation of myocardial Nrf2 in DOX-treated mice. Micafungin, an antifungal drug, was identified as a potential MALT1 inhibitor. This study aims to explore whether micafungin can reduce DOX-induced myocardial oxidative injury and if its anti-oxidative effect involves a suppression of MALT1-dependent k48-linked ubiquitination of Nrf2. To establish the cardiotoxicity models in vivo and in vitro, mice were treated with a single dose of DOX (15 mg/kg, i.p.) and cardiomyocytes were incubated with DOX (1 µM) for 24 h, respectively. Using mouse model of DOX-induced cardiotoxicity, micafungin (10 or 20 mg/kg) was shown to improve cardiac function, concomitant with suppression of oxidative stress, mitochondrial dysfunction, and cell death in a dose-dependent manner. Similar protective roles of micafungin (1 or 5 µM) were observed in DOX-treated cardiomyocytes. Mechanistically, micafungin weakened the interaction between MALT1 and Nrf2, decreased the k48-linked ubiquitination of Nrf2 while elevated the protein levels of Nrf2 in both DOX-treated mice and cardiomyocytes. Furthermore, MALT1 overexpression counteracted the cardioprotective effects of micafungin. In conclusion, micafungin reduces DOX-induced myocardial oxidative injury via suppression of MALT1, which decreases the k48-linked ubiquitination of Nrf2 and elevates Nrf2 protein levels. Thus, micafungin may be repurposed for treating DOX-induced cardiotoxicity.

CARD11-BCL10-MALT1 Complex-Dependent MALT1 Activation Facilitates Myocardial Oxidative Stress in Doxorubicin-Treated Mice via Enhancing k48-Linked Ubiquitination of Nrf2.

Aims: Downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) contributes to doxorubicin (DOX)-induced myocardial oxidative stress, and inhibition of mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) increased Nrf2 protein level in rat heart suffering ischemia/reperfusion, indicating a connection between MALT1 and Nrf2. This study aims to explore the role of MALT1 in DOX-induced myocardial oxidative stress and the underlying mechanisms. Results: The mice received a single injection of DOX (15 mg/kg, i.p.) to induce myocardial oxidative stress, evidenced by increases in the levels of reactive oxidative species as well as decreases in the activities of antioxidative enzymes, concomitant with a downregulation of Nrf2; these phenomena were reversed by MALT1 inhibitor. Similar phenomena were observed in DOX-induced oxidative stress in cardiomyocytes. Mechanistically, knockdown or inhibition of MALT1 notably attenuated the interaction between Nrf2 and MALT1 and decreased the k48-linked ubiquitination of Nrf2. Furthermore, inhibition or knockdown of calcium/calmodulin-dependent protein kinase II (CaMKII-δ) reduced the phosphorylation of caspase recruitment domain-containing protein 11 (CARD11), subsequently disrupted the assembly of CARD11, B cell lymphoma 10 (BCL10), and MALT1 (CBM) complex, and reduced the MALT1-dependent k48-linked ubiquitination of Nrf2 in DOX-treated mice or cardiomyocytes. Innovation and Conclusion: The E3 ubiquitin ligase function of MALT1 accounts for the downregulation of Nrf2 and aggravation of myocardial oxidative stress in DOX-treated mice, and CaMKII-δ-dependent phosphorylation of CARD11 triggered the assembly of CBM complex and the subsequent activation of MALT1.

The SPATA2/CYLD pathway contributes to doxorubicin-induced cardiomyocyte ferroptosis via enhancing ferritinophagy.

Ferroptosis is an iron-dependent cell death and contributes to doxorubicin-induced cardiotoxicity, but the mechanisms behind intracellular iron overload in cardiomyocyte after administration of doxorubicin remain largely unknown. Ferritinophagy is a selective type of autophagy and could be a novel source for intracellular free iron. Spermatogenesis-associated protein 2 (SPATA2), a member of the TNF signaling pathway, can recruit cylindromatosis (CYLD, a deubiquitinating enzyme) to regulate cell death. This study aims to explore whether ferritinophagy is the source for intracellular iron overload in cardiomyocyte upon doxorubicin treatment and whether the SPATA2/CYLD pathway is involved in regulation of nuclear receptor coactivator 4 (NCOA4) level, the selective cargo receptor for ferritinophagy. The C57BL/6J mice were subjected to a single injection of doxorubicin, which showed the compromised cardiac functions, accompanied by the upregulation of SPATA2 and CYLD and the enhanced interaction between them, the increases in ferritinophagy (reflecting by increases in NCOA4 and ratio of LC3Ⅱ/LC3Ⅰ while decreases in NCOA4 ubiquitination and ferritin) and ferroptosis (reflecting by intracellular iron overload and increase of acyl-CoA synthetase long chain family member 4). Consistently, similar results were achieved in the cultured cardiomyocytes after incubation with doxorubicin. Knocked down of SPATA2 notably reduced doxorubicin-induced cardiomyocyte injury concomitant with the attenuated ferritinophagy and the decreased ferroptosis. Based on these observations, we conclude that a novel pathway of SPATA2/CYLD has been identified, which contributes to doxorubicin-induced cardiomyocyte ferroptosis via enhancing ferritinophagy through a mechanism involving the deubiquitination of NCOA4.

Docosahexaenoic acid reduces hypoglycemia-induced neuronal necroptosis via the peroxisome proliferator-activated receptor γ/nuclear factor-κB pathway.

DHA has been shown to be neuroprotective and important to neurogenesis, but its role in HG-induced brain injury and the underlying mechanisms remain unknown. To elucidate the therapeutic effect of DHA, we established a mouse model with insulin-induced hypoglycemic brain injury and an in vitro model of HT-22 cells using a sugar-free medium. DHA treatment significantly reduced neuronal death and improved HG-induced learning and memory deficits. Moreover, DHA inhibited neuronal necroptosis and decreased the concentrations of TNF-α, IL-1ß and TNFR1. DHA also activated PPAR-γ and suppressed the NF-κB pathway in mouse brain tissues. In vitro, DHA treatment restored the viability and decreased necroptosis of HT-22 cells treated with glucose deprivation. However, the inhibition of PPAR-γ with T0070907 reversed neuroprotective and anti-necroptosis effects of DHA in HG-induced brain injury, which is associated with the activation of the downstream NF-κB pathway. We conclude that DHA displays a protective effect against HG-induced brain injury through the PPAR-γ/NF-κB pathway and represents a promising method to prevent HG-induced brain injury.

Allopurinol attenuates oxidative injury in rat hearts suffered ischemia/reperfusion via suppressing the xanthine oxidase/vascular peroxidase 1 pathway.

Allopurinol, a xanthine oxidase (XO) inhibitor, is reported to alleviate myocardial ischemia/reperfusion (I/R) injury by reducing the production of reactive oxygen species (ROS). As an XO-derived product, H2O2 can act as a substrate of vascular peroxidase 1 (VPO1) to induce the generation of hypochlorous acid (HOCl), a potent oxidant. This study aims to explore whether the XO/VPO1 pathway is involved in the anti-oxidative effects of allopurinol on the myocardial I/R injury. In a rat heart model of I/R, allopurinol alleviated I/R oxidative injury accompanied by decreased XO activity, XO-derived products (H2O2 and uric acid), and VPO1 expression (mRNA and protein). In a cardiac cell model of hypoxia/reoxygenation (H/R), allopurinol or XO siRNA reduced H/R injury concomitant with decreased XO activity, VPO1 expression as well as the XO and VPO1-derived products (H2O2, uric acid, and HOCl). Although knockdown of VPO1 could also exert a beneficial effect on H/R injury, it did not affect XO activity, XO expression, and XO-derived products. Based on these observations, we conclude that the novel pathway of XO/VPO1 is responsible for, at least partly, myocardial I/R-induced oxidative injury, and allopurinol exerted the cardioprotective effects on myocardial I/R injury via inhibiting the XO/VPO1 pathway.