Rationale:: Exercise training, in addition to reducing cardiovascular risk factors, confers direct protection against myocardial ischemia/reperfusion injury and has been associated with improved heart attack survival in humans. However, the underlying mechanisms of exercise-afforded cardioprotection are still unclear. Objective:: To investigate the role of exercise-derived circulating exosomes in cardioprotection and the molecular mechanisms involved. Methods and Results:: Circulating exosomes were isolated from the plasma of volunteers with or without exercise training and rats subjected to 4-week swim exercise or sedentary littermates 24 hours after the last training session. Although the total circulating exosome level did not change significantly in exercised subjects 24 hours post-exercise compared with the sedentary control, the isolated plasma exosomes from exercised rats afforded remarkable protection against myocardial ischemia/reperfusion injury. miRNA sequencing combined with quantitative reverse transcription polymerase chain reaction validation identified 12 differentially expressed miRNAs from the circulating exosomes of exercised rats, among which miR-342-5p stood out as the most potent cardioprotective molecule. Importantly, the cardioprotective effects and the elevation of exosomal miR-342-5p were also observed in exercise-trained human volunteers. Moreover, inhibition of miR-342-5p significantly blunted the protective effects of exercise-derived circulating exosomes in hypoxia/reoxygenation cardiomyocytes; in vivo cardiac-specific inhibition of miR-342-5p through serotype 9 adeno-associated virus–mediated gene delivery attenuated exercise-afforded cardioprotection in myocardial ischemia/reperfusion rats. Mechanistically, miR-342-5p inhibited hypoxia/reoxygenation-induced cardiomyocyte apoptosis via targeting Caspase 9 and Jnk2 ; it also enhanced survival signaling (p-Akt) via targeting phosphatase gene Ppm1f . Of note, exercise training or laminar shear stress directly enhanced the synthesis of miR-342-5p in endothelial cells. Conclusions:: Our findings reveal a novel endogenous cardioprotective mechanism that long-term exercise-derived circulating exosomes protect the heart against myocardial ischemia/reperfusion injury via exosomal miR-342-5p.

The involvement of cytoskeleton-related proteins in regulating mitochondrial respiration has been revealed in mammalian cells. However, it is unclear if there is a relationship between the microtubule-based motor protein kinesin and mitochondrial respiration. In this research, we demonstrate that a plant-specific kinesin, Kinesin-like protein 1 (KP1; At KIN14 h), is involved in respiratory regulation during seed germination at a low temperature. Using in vitro biochemical methods and in vivo transgenic cell observations, we demonstrate that KP1 is able to localize to mitochondria via its tail domain (C terminus) and specifically interacts with a mitochondrial outer membrane protein, voltage-dependent anion channel 3 (VDAC3). Targeting of the KP1-tail to mitochondria is dependent on the presence of VDAC3. When grown at 4°C, KP1 dominant-negative mutants (TAILOEs) and vdac3 mutants exhibited a higher seed germination frequency. All germinating seeds of the kp1 and vdac3 mutants had increased oxygen consumption; the respiration balance between the cytochrome pathway and the alternative oxidase pathway was disrupted, and the ATP level was reduced. We conclude that the plant-specific kinesin, KP1, specifically interacts with VDAC3 on the mitochondrial outer membrane and that both KP1 and VDAC3 regulate aerobic respiration during seed germination at low temperature.

Many biological processes require the co-operative involvement of both microtubules and microfilaments; however, only a few proteins mediating the interaction between microtubules and microfilaments have been identified from plants. In the present study, a cotton kinesin GhKCH2, which contains a CH (calponin homology) domain at the N-terminus, was analysed in vitro and in vivo in order to understand its interaction with the two cytoskeletal elements. A specific antibody against GhKCH2 was prepared and used for immunolabelling experiments. Some GhKCH2 spots appeared along a few microtubules and microfilaments in developing cotton fibres. The His-tagged N-terminus of GhKCH2 (termed GhKCH2-N) could co-precipitate with microfilaments and strongly bind to actin filaments at a ratio of monomeric actin/GhKCH2-N of 1:0.6. The full-length GhKCH2 recombinant protein was shown to bind to and cross-link microtubules and microfilaments in vitro. A GFP-fusion protein GFP–GhKCH2 transiently overexpressed in Arabidopsis protoplasts decorated both microtubules and microfilaments, confirming the binding ability and specificities of GhKCH2 on microtubules and microfilaments in living plant cells. The results of the present study demonstrate that GhKCH2, a plant-specific microtubule-dependent motor protein, not only interacts with microtubules, but also strongly binds to microfilaments. The cytoskeletal dual-binding and cross-linking ability of GhKCH2 may be involved in the interaction between microtubules and microfilaments and the biological processes they co-ordinate together in cotton cells.

Cardiac pacing is an effective therapy for treating patients with bradycardia due to sinus node dysfunction or atrioventricular block. However, traditional right ventricular apical pacing (RVAP) causes electric and mechanical dyssynchrony, which is associated with increased risk for atrial arrhythmias and heart failure. Therefore, there is a need to develop a physiological pacing approach that activates the normal cardiac conduction and provides synchronized contraction of ventricles. Although His bundle pacing (HBP) has been widely used as a physiological pacing modality, it is limited by challenging implantation technique, unsatisfactory success rate in patients with wide QRS wave, high pacing capture threshold, and early battery depletion. Recently, the left bundle branch pacing (LBBP), defined as the capture of left bundle branch (LBB) via transventricular septal approach, has emerged as a newly physiological pacing modality. Results from early clinical studies have demonstrated LBBP's feasibility and safety, with rare complications and high success rate. Overall, this approach has been found to provide physiological pacing that guarantees electrical synchrony of the left ventricle with low pacing threshold. This was previously specifically characterized by narrow paced QRS duration, large R waves, fast synchronized left ventricular activation, and correction of left bundle branch block. Therefore, LBBP may be a potential alternative pacing modality for both RVAP and cardiac resynchronization therapy with HBP or biventricular pacing (BVP). However, the technique's widespread adaptation needs further validation to ascertain its safety and efficacy in randomized clinical trials. In this review, we discuss the current knowledge of LBBP.

Atrial fibrillation (AF) is an increasingly prevalent arrhythmia with significant health and socioeconomic impact. The underlying mechanism of AF is still not well understood. In this study, we sought to identify hub genes involved in AF, and explored their functions and underlying mechanisms based on bioinformatics analysis. Five microarray datasets in GEO were used to identify the differentially expressed genes (DEGs) by Robust Rank Aggregation (RRA), and hub genes were screened out using protein–protein interaction (PPI) network. AF model was established using a mixture of acetylcholine and calcium chloride (Ach-CaCl₂) by tail vein injection. We totally got 35 robust DEGs that mainly involve in extracellular matrix formation, leukocyte transendothelial migration, and chemokine signaling pathway. Among these DEGs, we identified three hub genes involved in AF, of which CXCL12/CXCR4 axis significantly upregulated in AF patients stands out as one of the most potent targets for AF prevention, and its effect on AF pathogenesis and underlying mechanisms were investigated in vivo subsequently with the specific CXCR4 antagonist AMD3100 (6 mg/kg). Our results demonstrated an elevated transcription and translation of CXCL12/CXCR4 axis in AF patients and mice, accompanied with the anabatic atrial inflammation and fibrosis, thereby providing the substrate for AF maintenance. Blocking its signaling via AMD3100 administration in AF model mice reduced AF inducibility and duration, partly ascribed to decreased atrial inflammation and structural remodeling. Mechanistically, these effects were achieved by reducing the recruitment of CD3+ T lymphocytes and F4/80+ macrophages, and suppressing the hyperactivation of ERK1/2 and AKT/mTOR signaling in atria of AF model mice. In conclusion, this study provides new evidence that antagonizing CXCR4 prevents the development of AF, and suggests that CXCL12/CXCR4 axis may be a potential therapeutic target for AF.