Platelet function in patients with hypercholesterolaemia

Abstract. Platelets and plasma lipoproteins, particularly low density lipoprotein, have important roles in atherogenesis. Evidence from several sources suggests that important interactions occur between these individual components of the atherogeneic process. Here we review work from our own laboratory on platelet function in normal individuals and patients heterozygous for familial hypercholesterolaemia (FH). Data is presented on the role of platelet noradrenaline and also on altered cellular signalling in platelets from FH individuals who have plasma low density lipoprotein concentrations which are approximately double those seen in normal subjects.     

肿瘤坏死因子相关受体2介导的IRE1-JNK信号通路在染矽尘大鼠肺泡巨噬细胞凋亡中的作用

[目的]通过抑制肿瘤坏死因子相关受体2(TNFR2)后观察纳米二氧化硅粉尘对肺泡巨噬细胞的损伤程度,并进一步探索由TNFR2参与的肌醇酶1(IRE1)-C-Jun氨基端激酶(JNK)信号通路在介导肺泡巨噬细胞凋亡中的作用.[方法]将NR8383.1型大鼠肺泡巨噬细胞分为空白对照组、二氧化硅组(50mg/mL)和抗TNFR2组(在二氧化硅组基础上添加10 μg/mL anti-TNFR2抗体),同时每组设立3个平行样,培养24h后,检测各组肺泡巨噬细胞凋亡水平,IRE1-JNK信号通路相关蛋白(TNFR2、凋亡信号调控激酶1、JNK、激活蛋白1、Caspase12)含量. [结果]空白对照组肺泡巨噬细胞凋亡水平,TNFR2、凋亡信号调控激酶1、JNK、激活蛋白1及Caspase 12含量均低于二氧化硅组,抗TNFR2处理后上述指标均较二氧化硅组降低,但仍较空白对照组高. [结论] TNFR2可能在JNK-IRE1信号通路介导的肺泡巨噬细胞凋亡中发挥着重要作用.     

IP(3)R-mediated Ca(2+) release is modulated by anandamide in isolated cardiac nuclei

Cannabinoids (CBs) are known to alter coronary vascular tone and cardiac performance. They also exhibit cardioprotective properties, particularly in their ability to limit the damage produced by ischaemia reperfusion injury. The mechanisms underlying these effects are unknown. Here we investigate the intracellular localisation of CB receptors in the heart and examine whether they may modulate localised nuclear Ca²⁺ release. In isolated cardiac nuclear preparations, expression of both the inositol 1,4,5-trisphosphate receptor type 2 (IP₃R) and CB receptors (CB₁R and CB₂R) was demonstrated by immunoblotting. Both receptors localised to the nucleus and purity of the nuclear preparations was confirmed by co-expression of the nuclear marker protein nucleolin but absence of cytoplasmic actin. To measure effects of IP₃R and CBR agonists on nuclear Ca²⁺ release, isolated nuclei were loaded with Fluo5N-AM. This dye accumulates in the nuclear envelope. Isolated nuclei responded to IP₃ with rapid and transient Ca²⁺ release from the nuclear envelope. Anandamide inhibited this IP₃-mediated release. Preincubation of nuclear preparations with either the CB₁R antagonist (AM251) or the CB₂R antagonist (AM630) reversed anandamide-mediated inhibition to 80% and 60% of control values respectively. When nuclei were pre-treated with both CBR antagonists, anandamide-mediated inhibition of IP₃-induced Ca²⁺ release was completely reversed. These results are the first to demonstrate the existence of cardiac nuclear CB receptors. They are also the first to show that anandamide can negatively modulate IP₃-mediated nuclear Ca²⁺ release. As such, this provides evidence for a novel key mechanism underlying the action of CBs and CBRs in the heart.     

A synthetic peptide targeting the BH4 domain of Bcl-2 induces apoptosis in multiple myeloma and follicular lymphoma cells alone or in combination with agents targeting the BH3-binding pocket of Bcl-2

Bcl-2 inhibits apoptosis by two distinct mechanisms but only one is targeted to treat Bcl-2-positive malignancies. In this mechanism, the BH1-3 domains of Bcl-2 form a hydrophobic pocket, binding and inhibiting pro-apoptotic proteins, including Bim. In the other mechanism, the BH4 domain mediates interaction of Bcl-2 with inositol 1,4, 5-trisphosphate receptors (IP₃Rs), inhibiting pro-apoptotic Ca²⁺ signals. The current anti-Bcl-2 agents, ABT-263 (Navitoclax) and ABT-199 (Venetoclax), induce apoptosis by displacing pro-apoptotic proteins from the hydrophobic pocket, but do not inhibit Bcl-2-IP₃R interaction. Therefore, to target this interaction we developed BIRD-2 (Bcl-2 IP₃ Receptor Disruptor-2), a decoy peptide that binds to the BH4 domain, blocking Bcl-2-IP₃R interaction and thus inducing Ca²⁺-mediated apoptosis in chronic lymphocytic leukemia, multiple myeloma, and follicular lymphoma cells, including cells resistant to ABT-263, ABT-199, or the Bruton’s tyrosine kinase inhibitor Ibrutinib. Moreover, combining BIRD-2 with ABT-263 or ABT-199 enhances apoptosis induction compared to single agent treatment. Overall, these findings provide strong rationale for developing novel therapeutic agents that mimic the action of BIRD-2 in targeting the BH4 domain of Bcl-2 and disrupting Bcl-2-IP₃R interaction.     

Inositol-Related Gene Knockouts Mimic Lithium's Effect on Mitochondrial Function

The inositol-depletion hypothesis proposes that lithium attenuates phosphatidylinositol signaling. Knockout (KO) mice of two genes (IMPA1 or Slc5a3), each encoding for a protein related to inositol metabolism, were studied in comparison with lithium-treated mice. Since we previously demonstrated that these KO mice exhibit a lithium-like neurochemical and behavioral phenotype, here we searched for pathways that may mediate lithium''s/the KO effects. We performed a DNA-microarray study searching for pathways affected both by chronic lithium treatment and by the KO of each of the genes. The data were analyzed using three different bioinformatics approaches. We found upregulation of mitochondria-related genes in frontal cortex of lithium-treated, IMPA1 and Slc5a3 KO mice. Three out of seven genes differentially expressed in all three models, Cox5a, Ndufs7, and Ndufab, all members of the mitochondrial electron transfer chain, have previously been associated with bipolar disorder and/or lithium treatment. Upregulation of the expression of these genes was verified by real-time PCR. To further support the link between mitochondrial function and lithium''s effect on behavior, we determined the capacity of chronic low-dose rotenone, a mitochondrial respiratory chain complex I inhibitor, to alter lithium-induced behavior as measured by the forced-swim and the amphetamine-induced hyperlocomotion paradigms. Rontenone treatment counteracted lithium''s effect on behavior, supporting the proposition suggested by the bioinformatics analysis for a mitochondrial function involvement in behavioral effects of lithium mediated by inositol metabolism alterations.The results provide support for the notion that mitochondrial dysfunction is linked to bipolar disorder and can be ameliorated by lithium. The phenotypic similarities between lithium-treated wild-type mice and the two KO models suggest that lithium may affect behavior by altering inositol metabolism.