Mitochondrial hexokinase II (HKII) and phosphoprotein enriched in astrocytes (PEA15) form a molecular switch governing cellular fate depending on the metabolic state

The metabolic state of a cell is a key determinant in the decision to live and proliferate or to die. Consequently, balanced energy metabolism and the regulation of apoptosis are critical for the development and maintenance of differentiated organisms. Hypoxia occurs physiologically during development or exercise and pathologically in vascular disease, tumorigenesis, and inflammation, interfering with homeostatic metabolism. Here, we show that the hypoxia-inducible factor (HIF)-1-regulated glycolytic enzyme hexokinase II (HKII) acts as a molecular switch that determines cellular fate by regulating both cytoprotection and induction of apoptosis based on the metabolic state. We provide evidence for a direct molecular interactor of HKII and show that, together with phosphoprotein enriched in astrocytes (PEA15), HKII inhibits apoptosis after hypoxia. In contrast, HKII accelerates apoptosis in the absence of PEA15 and under glucose deprivation. HKII both protects cells from death during hypoxia and functions as a sensor of glucose availability during normoxia, inducing apoptosis in response to glucose depletion. Thus, HKII-mediated apoptosis may represent an evolutionarily conserved altruistic mechanism to eliminate cells during metabolic stress to the advantage of a multicellular organism.     

环状非编码RNA在眼部疾病中表达研究进展

环状非编码RNA（circRNA）是指一类不具有5’末端帽子和3’末端poly（A）尾巴的一类非编码RNA,其通过共价键形成环形结构,它们可以通过几种不同的机制调节蛋白质的编码。越来越多的研究发现,circRNA在细胞增殖、分化、凋亡、血管生成、免疫调节等多种细胞功能中发挥一定的作用,从而导致多种疾病（如恶性肿瘤、炎症性疾病、神经系统疾病等）的发生。本文综述了circRNA在眼科疾病中的潜在作用和可能机制,以期能够为相关眼科疾病的早期诊断和不同阶段的治疗提供新的思路。     

Hypercoagulation following brain death cannot be reversed by the neutralization of systemic tissue factor

Background

Cerebral injury and brain death is associated with apparent hypercoagulation and poor organ outcome. This experimental study challenges the hypotheses that i) brain death causes hypercoagulation and microvascular thrombosis and that ii) neutralizing systemic tissue factor (TF) by in vitro addition of a TF inhibitor (recombinant active site-inhibited factor VIIa (ASIS)) can reverse the hypercoagulable profile.

Methods

Using a validated pig model of intracranial hemorrhage and brain death, 20 pigs were randomized to either control or brain death. The primary endpoints were coagulation parameters measured with whole blood thromboelastometry (ROTEM), thrombin generation and a porcine TF-sensitive plasma clotting time assay. In vitro spiking experiments with ASIS were performed in parallel with the latter two assessments. The kidneys were examined histologically for microvascular thromboses.

Results

Brain death induced hypercoagulation, as demonstrated with ROTEM, thrombin generation, and reduced TF-sensitive plasma clotting time. In vitro inhibition of TF with ASIS did not reverse the hypercoagulation. No microvascular thromboses were found in the kidneys.

Conclusion

Brain death causes hypercoagulation; however, inhibition of TF does not reverse the coagulopathy. Thus, TF release does not seem to be the primary cause of this hypercoagulation. Minor changes in the levels of protein C suggest that the protein C pathway may be linked to the observed coagulopathy.     

Enhanced thrombin generation in women with a history of oral contraception-related venous thrombosis

Introduction

In women who suffer venous thrombosis (VT) during oral contraceptive (OC) use, a transient risk factor (OC) is removed during the acute event, while most co-existing forms of thrombophilia persist and presumably continue to maintain hypercoagulability. The aim of this study was to establish if hypercoagulability persists long after OC-related VT and if it could be attributed to thrombophilia.

Materials and Methods

60 women (age 33.0 ± 8.5 years) were investigated 5 – 64 (median 33) months after OC-related VT (patients) and compared to 63 apparently healthy women (controls). All women were tested for thrombophilia, activated partial thromboplastin time (APTT), fibrinogen, D-dimer, P-selectin and C-reactive protein. Thrombin generation was measured by Technothrombin® TGA assay. Overall haemostasis potential (OHP) assay with overall coagulation potential (OCP) and overall fibrinolytic potential (OFP) as supplementary parameters were measured by repeated fibrin formation and degradation registration.

Results

In patients increased endogenous thrombin potential (4205 ± 440 nM x min vs 4015 ± 421 nM x min, p = 0.017), increased OCP (22.6 ± 4.6 Abs-sum vs 20.8 ± 4.1 Abs-sum, p = 0.025), shorter APTT (30.9 ± 3.8 s vs 33.4 ± 3.6 s, p < 0.001) and lower antithrombin activity (99, 93-105% vs 104, 100-109%, p < 0.05) were observed. Thrombophilia was observed in 22/60 (36%) patients and in 5/63 (7.9%, p < 0.001) controls. The only significant difference between thrombophilic and non-thrombophilic patients was higher soluble P-selectin in the former subgroup (22, 20-33 μg/L vs 17, 12-22 μg/L, p = 0.012).

Conclusions

In women with a history of OC-related VT persistent hypercoagulability was observed, which, however was not augmented by the presence of thrombophilia.     

When words are painful: unraveling the mechanisms of the nocebo effect

The nocebo effect is a phenomenon that is opposite to the placebo effect, whereby expectation of a negative outcome may lead to the worsening of a symptom. Thus far, its study has been limited by ethical constraints, particularly in patients, as a nocebo procedure is per se stressful and anxiogenic. It basically consists in delivering verbal suggestions of negative outcomes so that the subject expects clinical worsening. Although some natural nocebo situations do exist, such as the impact of negative diagnoses upon the patient and the patient's distrust in a therapy, the neurobiological mechanisms have been understood in the experimental setting under strictly controlled conditions. As for the placebo counterpart, the study of pain has been fruitful in recent years to understand both the neuroanatomical and the neurochemical bases of the nocebo effect. Recent experimental evidence indicates that negative verbal suggestions induce anticipatory anxiety about the impending pain increase, and this verbally-induced anxiety triggers the activation of cholecystokinin (CCK) which, in turn, facilitates pain transmission. CCK-antagonists have been found to block this anxiety-induced hyperalgesia, thus opening up the possibility of new therapeutic strategies whenever pain has an important anxiety component. Other conditions, such as Parkinson's disease, although less studied, have been found to be affected by nocebo suggestions as well. All these findings underscore the important role of cognition in the therapeutic outcome, and suggest that nocebo and nocebo-related effects might represent a point of vulnerability both in the course of a disease and in the response to a therapy.     

Functional epitopes on porcine endogenous retrovirus envelope protein interacting with neutralizing antibody combining sites

Porcine cell and organ transplantation provides promise for maintaining normal physiological conditions in patients with end-stage organ failure. The approach however poses serious risk of transmitting pig pathogens to humans. Among many potential pathogens, porcine endogenous retroviruses (PERV) are of particular concern due to their ubiquitous nature in pigs and capability of infecting human cells. Major antigenic determinants and receptor binding domains on PERV remain unclear until now. Two monoclonal antibodies (mAb), named 8E10 and 7C4 capable of neutralizing PERV infection in HEK293 cells are isolated at an IC(50) of 3.0 and 2.7 microg/ml, respectively, in this work. Epitope location for mAb 8E10 was mapped to amino acids 427-434, residing at the C-terminal region of the gp70 component of type A PERV Env protein. The mAb 8E10 bound directly to the PERV indicating that the epitope is exposed on the virion surface. The mAb 7C4 epitope was assigned to the region comprising amino acids 517-537 on the p15E component of PERV. In contrast to mAb 8E10, the 7C4 mAb bound native PERV inefficiently suggesting that its epitope is accessible only after the virus interacts with its receptor. Finally, both mAbs variable regions were cloned and nucleotide sequence determined. All together, these results reveal that both mAbs 8E10 and 7C4 effectively neutralize PERV infection and may be used as a mean to prevent PERV infection in patients receiving xenotransplantation.