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Targeting Glycogen Synthase Kinase 3 Beta Regulates CD47 Expression After Myocardial Infarction in Rats via the NF-κB Signaling Pathway.

ABSTRACT: The aim of this study was to investigate the effects of the GSK-3β/NF-κB pathway on integrin-associated protein (CD47) expression after myocardial infarction (MI) in rats. An MI Sprague Dawley rat model was established by ligating the left anterior descending coronary artery. The rats were divided into three groups: Sham, MI, and SB + MI (SB216763) groups. Immunohistochemistry was used to observe the changes in cardiac morphology. A significant reduction in the sizes of fibrotic scars was observed in the SB + MI group compared to that in the MI group. SB216763 decreased the mRNA and protein expression of CD47 and NF-κB during MI. Primary rat cardiomyocytes (RCMs) and the H9c2 cell line were used to establish in vitro hypoxia models. Quantitative real-time PCR and western blotting analyses were conducted to detect mRNA and protein expression levels of CD47 and NF-κB and apoptosis-related proteins, respectively. Apoptosis of hypoxic cells was assessed using flow cytometry. SB216763 reduced the protein expression of CD47 and NF-κB in RCMs and H9c2 cells under hypoxic conditions for 12 h, and alleviated hypoxia-induced apoptosis. SN50 (an NF-κB inhibitor) also decreased CD47 protein expression in RCMs and H9c2 cells under hypoxic conditions for 12 h and protected cells from apoptosis. GSK-3β upregulates CD47 expression in cardiac tissues after MI by activating NF-κB, which in turn leads to myocardial cell damage and apoptosis.

SUBMITTER: Xu LN

PROVIDER: S-EPMC8327268 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The molecular pathways that regulate the extent of ischemic injury and post-myocardial infarction (MI) remodeling are not well understood. We recently demonstrated that glycogen synthase kinase-3? (GSK-3?) is critical to the heart's response to pressure overload. However, the role, if any, of GSK-3? in regulating ischemic injury and its consequences is not known.MI was induced in wild-type (WT) versus GSK-3?((-/-)) (KO) littermates by left anterior descending coronary artery ligation. Pre-MI, WT, and KO hearts had comparable chamber dimensions and ventricular function, but as early as 1 week post-MI, KO mice had significantly more left ventricular dilatation and dysfunction than WT mice. KO mice also had increased mortality during the first 10 days post-MI (43% versus 22%; P=0.04), and postmortem examination confirmed cardiac rupture as the cause of most of the deaths. In the mice that survived the first 10 days, left ventricular dilatation and dysfunction remained worse in the KO mice throughout the study (8 weeks). Hypertrophy, fibrosis, and heart failure were all increased in the KO mice. Given the early deaths due to rupture and the significant reduction in left ventricular function evident as early as 1 week post-MI, we examined infarct size following a 48-hour coronary artery ligation and found it to be increased in the KO mice. This was accompanied by increased apoptosis in the border zone of the MI. This increased susceptibility to ischemic injury-induced apoptosis was also seen in cardiomyocytes isolated from the KO mice that were exposed to hypoxia. Finally, Bax translocation to the mitochondria and cytochrome C release into the cytosol were increased in the KO mice.GSK-3? confers resistance to ischemic injury, at least in part, via limiting apoptosis. Loss of GSK-3? promotes ischemic injury, increases risk of cardiac rupture, accentuates post-MI remodeling and left ventricular dysfunction, and increases the progression to heart failure. These findings are in striking contrast to multiple previous reports in which deletion or inhibition of GSK-3? is protective.

Project description:Glycogen synthase kinase-3? (GSK-3?), a serine/threonine protein kinase, may function as a tumor suppressor or an oncogene, depending on the tumor type. We sought to determine the biological function of GSK-3? in osteosarcoma, a rare pediatric cancer for which the identification of new therapeutic targets is urgent.We used cell viability assays, colony formation assays, and apoptosis assays to analyze the effects of altered GSK-3? expression in U2OS, MG63, SAOS2, U2OS/MTX300, and ZOS osteosarcoma cell lines. Nude mice (n = 5-8 mice per group) were injected with U2OS/MTX300, and ZOS cells to assess the role of GSK-3? in osteosarcoma growth in vivo and to evaluate the effects of inhibitors and/or anticancer drugs on tumor growth. We used an antibody array, polymerase chain reaction, western blotting, and a luciferase reporter assay to establish the effect of GSK-3? inhibition on the nuclear factor-?B (NF-?B) pathway. Immunochemistry was performed on primary tumor specimens from osteosarcoma patients (n = 74) to determine the relationship of GSK-3? activity with overall survival.Osteosarcoma cells with low levels of inactive p-Ser9-GSK-3? formed colonies in vitro and tumors in vivo more readily than cells with higher levels and cells in which GSK-3? had been silenced formed fewer colonies and smaller tumors than parental cells. Silencing or pharmacological inhibition of GSK-3? resulted in apoptosis of osteosarcoma cells. Inhibition of GSK-3? resulted in inhibition of the NF-?B pathway and reduction of NF-?B-mediated transcription. Combination treatments with GSK-3? inhibitors, NF-?B inhibitors, and chemotherapy drugs increased the effectiveness of chemotherapy drugs in vitro and in vivo. Patients whose osteosarcoma specimens had hyperactive GSK-3?, and nuclear NF-?B had a shorter median overall survival time (49.2 months) compared with patients whose tumors had inactive GSK-3? and NF-?B (109.2 months).GSK-3? activity may promote osteosarcoma tumor growth, and therapeutic targeting of the GSK-3? and/or NF-?B pathways may be an effective way to enhance the therapeutic activity of anticancer drugs against osteosarcoma.

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Targeting Glycogen Synthase Kinase 3 Beta Regulates CD47 Expression After Myocardial Infarction in Rats via the NF-κB Signaling Pathway.

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