Tetramethylpyrazine Attenuates the Endotheliotoxicity and the Mitochondrial Dysfunction by Doxorubicin via 14-3-3γ/Bcl-2.
Doxorubicin (Dox) with cardiotoxicity and endotheliotoxicity limits its clinical application for cancer. The toxicitic mechanism involves excess ROS generation. 14-3-3s have the protective effects on various injured tissues and cells. Tetramethylpyrazine (TMP) is an alkaloid extracted from the rhizome of Ligusticum wallichii and has multiple bioactivities. We hypothesize that TMP has the protective effects on vascular endothelium by upregulating 14-3-3γ. To test the hypothesis, Dox-induced endotheliotoxicity was used to establish vascular endothelium injury models in mice and human umbilical vein endothelial cells. The effects of TMP were assessed by determining thoracic aortic strips' endothelium-dependent dilation (EDD), as well as LDH, CK, caspase-3, SOD, CAT, GSH-Px activities and MDA level in serum, apoptotic rate, and histopathological changes of vascular tissue (in vivo). Also, cell viability, LDH and caspase-3 activities, ROS generation, levels of NAD+/NADH and GSH/GSSG, MMP, mPTP opening, and apoptotic rate were evaluated (in vitro). The expression of 14-3-3γ and Bcl-2, as well as phosphorylation of Bad (S112), were determined by Western blot. Our results showed that Dox-induced injury to vascular endothelium was decreased by TMP via upregulating 14-3-3γ expression in total protein and Bcl-2 expression in mitochondria, activating Bad (S112) phosphorylation, maintaining EDD, reducing LDH, CK, and caspase-3 activities, thereby causing a reduction in apoptotic rate, and histopathological changes of vascular endothelium (in vivo). Furthermore, TMP increased cell viability and MMP levels, maintained NAD+/NADH, GSH/GSSG balance, decreased LDH and caspase-3 activities, ROS generation, mPTP opening, and apoptotic rate (in vitro). However, the protective effects to vascular endothelium of TMP were significantly canceled by pAD/14-3-3γ-shRNA, an adenovirus that caused knockdown 14-3-3γ expression, or ABT-737, a specific Bcl-2 inhibitor. In conclusion, this study is the first to demonstrate that TMP protects the vascular endothelium against Dox-induced injury via upregulating 14-3-3γ expression, promoting translocation of Bcl-2 to the mitochondria, closing mPTP, maintaining MMP, inhibiting RIRR mechanism, suppressing oxidative stress, improving mitochondrial function, and alleviating Dox-induced endotheliotoxicity.
Yang B
，Li H
，Qiao Y
，Zhou Q
，Chen S
，Yin D
，He H
，He M
... -
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Tetramethylpyrazine attenuates lipopolysaccharide-induced cardiomyocyte injury via improving mitochondrial function mediated by 14-3-3γ.
Lipopolysaccharide (LPS) is one of the many reasons that can cause myocardial injury. Our previous works have demonstrated that 14-3-3γ could protect myocardium against LPS-induced injury. Tetramethylpyrazine (TMP), an alkaloid found in Chinese herbs, exerts myocardial protection in many ways with multiple targets. We hypothesized that the cardioprotection of TMP against LPS-induced injury is attributed to upregulation of 14-3-3γ and improvement of mitochondrial function. To test the hypothesis, we investigated the effects of TMP on LPS-induced injury to cardiomyocytes by determining cell viability, LDH and caspase-3 activities, reactive oxygen species and MMP levels, mPTP openness, and apoptosis rate. The expression of 14-3-3γ and Bcl-2, and the phosphorylation of Bad (S112) were examined by Western blot. LPS-induced injury to cardiomyocytes was attenuated by TMP via upregulating expression of 14-3-3γ, and Bcl-2 on mitochondria, activating Bad (S112) phosphorylation, increasing cell viability and MMP levels, decreasing LDH and caspase-3 activity, reactive oxygen species generation, mPTP opening and apoptosis rate. However, the cardioprotection of TMP was attenuated by pAD/14-3-3γ-shRNA, an adenovirus that knocked down intracellular 14-3-3γ expression. In conclusion, the cardioprotection of TMP against LPS-induced injury was through up-regulating the expression of 14-3-3γ, promoting the translocation of Bcl-2 to mitochondria, and improving the function of mitochondria.
Huang B
，You J
，Qiao Y
，Wu Z
，Liu D
，Yin D
，He H
，He M
... -
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