Melatonin protects cardiac microvasculature against ischemia/reperfusion injury via suppression of mitochondrial fission‐VDAC1‐HK2‐mPTP‐mitophagy axis

Abstract

The cardiac microvascular system, which is primarily composed of monolayer endothelial cells, is the site of blood supply and nutrient exchange to cardiomyocytes. However, microvascular ischemia/reperfusion injury (IRI) following percutaneous coronary intervention is a woefully neglected topic, and few strategies are available to reverse such pathologies. Here, we studied the effects of melatonin on microcirculation IRI and elucidated the underlying mechanism. Melatonin markedly reduced infarcted area, improved cardiac function, restored blood flow, and lower microcirculation perfusion defects. Histological analysis showed that cardiac microcirculation endothelial cells (CMEC) in melatonin‐treated mice had an unbroken endothelial barrier, increased endothelial nitric oxide synthase expression, unobstructed lumen, reduced inflammatory cell infiltration, and less endothelial damage. In contrast, AMP‐activated protein kinase α (AMPKα) deficiency abolished the beneficial effects of melatonin on microvasculature. In vitro, IRI activated dynamin‐related protein 1 (Drp1)‐dependent mitochondrial fission, which subsequently induced voltage‐dependent anion channel 1 (VDAC1) oligomerization, hexokinase 2 (HK2) liberation, mitochondrial permeability transition pore (mPTP) opening, PINK1/Parkin upregulation, and ultimately mitophagy‐mediated CMEC death. However, melatonin strengthened CMEC survival via activation of AMPKα, followed by p‐Drp1S616 downregulation and p‐Drp1S37 upregulation, which blunted Drp1‐dependent mitochondrial fission. Suppression of mitochondrial fission by melatonin recovered VDAC1‐HK2 interaction that prevented mPTP opening and PINK1/Parkin activation, eventually blocking mitophagy‐mediated cellular death. In summary, this study confirmed that melatonin protects cardiac microvasculature against IRI. The underlying mechanism may be attributed to the inhibitory effects of melatonin on mitochondrial fission‐VDAC1‐HK2‐mPTP‐mitophagy axis via activation of AMPKα.

YAP Inhibits the Apoptosis and Migration of Human Rectal Cancer Cells via Suppression of JNK-Drp1-Mitochondrial Fission-HtrA2/Omi Pathways

“…Co-immunoprecipitation experiments were performed as previously described [11]. Briefly, cells were lysed by sonication in PBS with 1% Triton X-100 and incubated with the respective antibodies and protein A/G agarose beads.…”

“…Scrambled shRNA control or shRNA specific to Yap was constructed using a lentiviral shRNA technique (GeneChem), as described previously [10, 11]. The shRNA was used to generate the stable cell line SW837 without expression of Yap.…”

“…Immunofluorescence staining was performed as previously described [11]. The primary antibodies used were as follows: Yap (1: 1500, Cell Signaling Technology, #8418), JNK (1: 1000, Abcam, #ab124956), F-actin (1: 500, Abcam, #ab205), tubulin (1: 1000, Abcam, #ab7291), Drp1 (1: 500, Cell Signaling Technology, #3455), HtrA2/Omi, (1: 500, Abcam, #ab21307).…”

“…Previous studies [10, 11] have found that mitochondria also act as messengers to transmit or amplify damage signals via mitochondrial dynamics, a process that balances mitochondrial fusion and fission events to regulate the structure and function of the mitochondrion. Normally, mitochondrial fusion enables the exchange of proteins, lipids, and mitochondrial DNA and ATP across distances within the cell, which is essential to meet the metabolic demands of the cell [12].…”

Effect of Mst1 on Endometriosis Apoptosis and Migration: Role of Drp1-Related Mitochondrial Fission and Parkin-Required Mitophagy

“…These data indicate that mitochondria homeostasis could be considered a therapeutic target for the treatment of endometriosis. Notably, recent studies show that mitochondrial dynamics, especially Drp1-related mitochondrial fission, happen at the early stage of cellular apoptosis, such as in liver cancer, cardiomyocytes and neurocytes [6,7]. Excessive mitochondrial fission initiates caspase 9-related mitochondrial apoptosis, leading to cell death [8,9].…”