Small molecule agonist of mitochondrial fusion repairs mitochondrial dysfunction.

Membrane dynamics are important to the integrity and function of mitochondria. Defective mitochondrial fusion underlies the pathogenesis of multiple diseases. The ability to target fusion highlights the potential to fight life-threatening conditions. Here we report a small molecule agonist, S89, that specifically promotes mitochondrial fusion by targeting endogenous MFN1. S89 interacts directly with a loop region in the helix bundle 2 domain of MFN1 to stimulate GTP hydrolysis and vesicle fusion. GTP loading or competition by S89 dislodges the loop from the GTPase domain and unlocks the molecule. S89 restores mitochondrial and cellular defects caused by mitochondrial DNA mutations, oxidative stress inducer paraquat, ferroptosis inducer RSL3 or CMT2A-causing mutations by boosting endogenous MFN1. Strikingly, S89 effectively eliminates ischemia/reperfusion (I/R)-induced mitochondrial damage and protects mouse heart from I/R injury. These results reveal the priming mechanism for MFNs and provide a therapeutic strategy for mitochondrial diseases when additional mitochondrial fusion is beneficial.

The critical role of the zinc transporter Zip2 (SLC39A2) in ischemia/reperfusion injury in mouse hearts.

Although zinc homeostasis has been demonstrated to play a role in myocardial ischemia/reperfusion (I/R) injury, the roles of zinc transporters that are critical for zinc homeostasis in I/R injury are poorly understood. The purpose of this study was to test if Zip2, an important zinc importer, plays a role in I/R injury in mouse hearts and explore the mechanism by which Zip2 expression is regulated. Zip2 expression was increased at reperfusion in in vivo mouse hearts, an effect that was abolished by ZnCl2, indicating Zip2's attempt to compensate for zinc loss at reperfusion. Further studies showed that upregulation of Zip2 expression was reversed by either pharmacological or genetic inhibition of signal transducers and activators of transcription 3 (STAT3), whereas STAT3 overexpression increased Zip2 expression, indicating that STAT3 accounts for Zip2 upregulation. In support, reperfusion enhanced STAT3 phosphorylation (Tyr705), which was blocked by ZnCl2, implying that STAT3 is activated in response to zinc loss. To determine the role of Zip2 in I/R injury, we assessed I/R injury by genetically disrupting Zip2 expression. Knockout of Zip2 genes (Zip2+/- and Zip2-/-) exacerbated I/R injury by increasing infarct size as well as the serum LDH, troponin I (cTnI), and CK-MB activities. In contrast, delivery of Zip2 genes reduced I/R injury. Delivery of STAT3 genes increased STAT3 phosphorylation and reduced I/R injury. However, delivery of the dominant negative STAT3 mutant did not reduce I/R injury. Moreover, delivery of STAT3 genes failed to reduce I/R injury in Zip2-/- mice. Zip2 upregulated upon reperfusion via STAT3 is cardioprotective and this upregulation may serve as an important intrinsic protective mechanism by which the heart is resistant to I/R injury. The factors involved in the zinc homeostasis (zinc and Zip2) are responsible STAT3 activation and its subsequent cardioprotective action.

Diagnostic value of interleukins for tuberculous pleural effusion: a systematic review and meta-analysis.

BACKGROUND: The ability of interleukins (ILs) to differentiate tuberculous pleural effusion from other types of effusion is controversial. The aim of our study was to summarize the evidence for its use of ruling out or in tuberculous pleural effusion. METHODS: Two investigators independently searched PubMed, EMBASE, Web of Knowledge, CNKI, WANFANG, and WEIPU databases to identify studies assessing diagnostic role of ILs for tuberculous pleural effusion published up to January, 2017. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. The pooled diagnostic sensitivity and specificity of ILs were calculated by using Review Manager 5.3. Area under the summary receiver operating characteristic curve (AUC) was used to summarize the overall diagnostic performance of individual markers. RESULTS: Thirty-eight studies met our inclusion criteria. Pooled sensitivity, specificity and AUC for chosen ILs were as follows: IL-2, 0.67,0.76 and 0.86; IL-6, 0.86, 0.84 and 0.90; IL-12, 0.78, 0.83 and 0.86; IL-12p40, 0.82,0.65 and 0.76; IL-18, 0.87, 0.92 and 0.95; IL-27, 0.93, 0.95 and 0.95; and IL-33, 0.84, 0.80 and 0.88. CONCLUSIONS: Some of these ILs may assist in diagnosing tuberculous pleural effusion, though no single IL is likely to show adequate sensitivity or specificity on its own. Further studies on a large scale with better study design should be performed to assess the diagnostic potential of ILs.

Zinc prevents mitochondrial superoxide generation by inducing mitophagy in the setting of hypoxia/reoxygenation in cardiac cells.

Zinc plays a role in autophagy and protects cardiac cells from ischemia/reperfusion injury. This study aimed to test if zinc can induce mitophagy leading to attenuation of mitochondrial superoxide generation in the setting of hypoxia/reoxygenation (H/R) in cardiac cells. H9c2 cells were subjected to 4 h hypoxia followed by 2 h reoxygenation. Under normoxic conditions, treatments of cells with ZnCl2 increased both the LC3-II/LC3-I ratio and GFP-LC3 puncta, implying that zinc induces autophagy. Further experiments showed that endogenous zinc is required for the autophagy induced by starvation and rapamycin. Zinc down-regulated TOM20, TIM23, and COX4 both in normoxic cells and the cells subjected to H/R, indicating that zinc can trigger mitophagy. Zinc increased ERK activity and Beclin1 expression, and zinc-induced mitophagy was inhibited by PD98059 and Beclin1 siRNA during reoxygenation. Zinc-induced Beclin1 expression was reversed by PD98059, implying that zinc promotes Beclin1 expression via ERK. In addition, zinc failed to induce mitophagy in cells transfected with PINK1 siRNA and stabilized PINK1 in mitochondria. Moreover, zinc-induced PINK1 stabilization was inhibited by PD98059. Finally, zinc prevented mitochondrial superoxide generation and dissipation of mitochondrial membrane potential (ΔΨm) at reoxygenation, which was blocked by both the Beclin1 and PINK1 siRNAs, suggesting that zinc prevents mitochondrial oxidative stress through mitophagy. In summary, zinc induces mitophagy through PINK1 and Beclin1 via ERK leading to the prevention of mitochondrial superoxide generation in the setting of H/R. Clearance of damaged mitochondria may account for the cardioprotective effect of zinc on H/R injury.