Aims Heart failure is a major complication in cancer treatment due to the cardiotoxic effects of anticancer drugs, especially from the anthracyclines such as doxorubicin (DXR). DXR enhances oxidative stress and stimulates matrix metalloproteinase-2 (MMP-2) in cardiomyocytes. We investigated whether MMP inhibitors protect against DXR cardiotoxicity given the role of MMP-2 in proteolyzing sarcomeric proteins in the heart and remodelling the extracellular matrix. Methods and results Eight-week-old male C57BL/6J mice were treated with DXR weekly with or without MMP inhibitors doxycycline or ONO-4817 by daily oral gavage for 4 weeks. Echocardiography was used to determine cardiac function and left ventricular remodelling before and after treatment. MMP inhibitors ameliorated DXR-induced systolic and diastolic dysfunction by reducing the loss in left ventricular ejection fraction, fractional shortening, and E′/A′. MMP inhibitors attenuated adverse left ventricular remodelling, reduced cardiomyocyte dropout, and prevented myocardial fibrosis. DXR increased myocardial MMP-2 activity in part also by upregulating N-terminal truncated MMP-2. Immunogold transmission electron microscopy showed that DXR elevated MMP-2 levels within the sarcomere and mitochondria which were associated with myofilament lysis, mitochondrial degeneration, and T-tubule distention. DXR-induced myofilament lysis was associated with increased titin proteolysis in the heart which was prevented by ONO-4817. DXR also increased the level and activity of MMP-2 in human embryonic stem cell-derived cardiomyocytes, which was reduced by ONO-4817. Conclusions MMP-2 activation is an early event in DXR cardiotoxicity and contributes to myofilament lysis by proteolyzing cardiac titin. Two orally available MMP inhibitors ameliorated DXR cardiotoxicity by attenuating intracellular and extracellular matrix remodelling, suggesting their use may be a potential prophylactic strategy to prevent heart injury during chemotherapy.
Aims Matrix metalloproteinase-2 (MMP-2) is a zinc-dependent protease which contributes to cardiac contractile dysfunction when activated during myocardial ischaemia–reperfusion (IR) injury. MMP-2 is localized to several subcellular sites inside cardiac myocytes; however, its role in the sarcoplasmic reticulum (SR) is unknown. The Ca2+ ATPase SERCA2a, which pumps cytosolic Ca2+ into the SR to facilitate muscle relaxation, is degraded in cardiac IR injury; however, the protease responsible for this is unclear. We hypothesized that MMP-2 contributes to cardiac contractile dysfunction by proteolyzing SERCA2a, thereby impairing its activity in IR injury. Methods and results Isolated rat hearts were subjected to IR injury in the presence or absence of the selective MMP inhibitor ARP-100, or perfused aerobically as a control. Inhibition of MMP activity with ARP-100 significantly improved the recovery of cardiac mechanical function and prevented the increase of a 70 kDa SERCA2a degradation fragment following IR injury, although 110 kDa SERCA2a and phospholamban levels appeared unchanged. Electrophoresis of IR heart samples followed by LC-MS/MS confirmed the presence of a SERCA2a fragment of ∼70 kDa. MMP-2 activity co-purified with SR-enriched microsomes prepared from the isolated rat hearts. Endogenous SERCA2a in SR-enriched microsomes was proteolyzed to ∼70 kDa products when incubated in vitro with exogenous MMP-2. MMP-2 also cleaved purified porcine SERCA2a in vitro. SERCA activity in SR-enriched microsomes was decreased by IR injury; however, this was not prevented with ARP-100. Conclusion This study shows that MMP-2 activity is found in SR-enriched microsomes from heart muscle and that SERCA2a is proteolyzed by MMP-2. The cardioprotective actions of MMP inhibition in myocardial IR injury may include the prevention of SERCA2a degradation.
Multiple sclerosis (MS) is a progressive and inflammatory demyelinating disease of the CNS. Peroxisomes perform critical functions that contribute to CNS homeostasis. We investigated peroxisome injury and mitigating effects of peroxisome-restorative therapy on inflammatory demyelination in models of MS. Human autopsied CNS tissues (male and female), human cell cultures, and cuprizonemediated demyelination mice (female) were examined by RT-PCR, Western blotting, and immunolabeling. The therapeutic peroxisome proliferator, 4-phenylbutyrate (4-PBA) was investigated in vitro and in vivo. White matter from MS patients showed reduced peroxisomal transcript and protein levels, including PMP70, compared with non-MS controls. Cultured human neural cells revealed that human microglia contained abundant peroxisomal proteins. TNF-a-exposed microglia displayed reduced immunolabeling of peroxisomal proteins, PMP70 and PEX11b, which was prevented with 4-PBA. In human myeloid cells exposed to TNF-a or nigericin, suppression of PEX11b and catalase protein levels were observed to be dependent on NLRP3 expression. Hindbrains from cuprizoneexposed mice showed reduced Abcd1, Cat, and Pex5l transcript levels, with concurrent increased Nlrp3 and Il1b transcript levels, which was abrogated by 4-PBA. In the central corpus callosum, Iba-1 in CNS-associated macrophages and peroxisomal thiolase immunostaining after cuprizone exposure was increased by 4-PBA. 4-PBA prevented decreased myelin basic protein and neurofilament heavy chain immunoreactivity caused by cuprizone exposure. Cuprizone-induced neurobehavioral deficits were improved by 4-PBA treatment. Peroxisome injury in CNS-associated macrophages contributed to neuroinflammation and demyelination that was prevented by 4-PBA treatment. A peroxisome-targeted therapy might be valuable for treating inflammatory demyelination and neurodegeneration in MS.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.