The human hypoxia-inducible transcription factor HIF-1 is a critical regulator of cellular and systemic responses to low oxygen levels. When oxygen levels are high, the HIF-1alpha subunit is hydroxylated and is targeted for degradation by the von Hippel-Lindau tumor suppressor protein (VHL). This regulatory pathway is evolutionarily conserved, and the Caenorhabditis elegans hif-1 and vhl-1 genes encode homologs of the HIF-1alpha subunit and VHL. To understand and describe more fully the molecular basis for hypoxia response in this important genetic model system, we compared hypoxia-induced changes in mRNA expression in wild-type, hif-1-deficient, and vhl-1-deficient C. elegans using whole genome microarrays. These studies identified 110 hypoxia-regulated gene expression changes, 63 of which require hif-1 function. Mutation of vhl-1 abrogates most hif-1-dependent changes in mRNA expression. Genes regulated by C. elegans hif-1 have predicted functions in signal transduction, metabolism, transport, and extracellular matrix remodeling. We examined the in vivo requirement for 16 HIF-1 target genes and discovered that the phy-2 prolyl 4-hydroxylase alpha subunit is critical for survival in hypoxic conditions. Some HIF-1 target genes negatively regulate formation of stress-resistant dauer larvae. The microarray data presented herein also provide clear evidence for an HIF-1-independent pathway for hypoxia response, and this pathway regulates the expression of multiple heat shock proteins and several transcription factors.
Abstract Background Intracerebral hemorrhage (ICH) is a common cerebrovascular disease, and the complement cascade exacerbates brain injury after ICH. As the most abundant component of the complement system, complement component 3 (C3) plays essential roles in all three complement pathways. However, the effects of C3 on neurological impairment and brain injury in ICH patients and the related mechanism have not been fully elucidated. Normobaric hyperoxia (NBO) is regarded as a treatment for ICH patients, and recent clinical studies also have confirmed the neuroprotective role of NBO against acute ICH‐mediated brain damage, but the underlying mechanism still remains elusive. Aims In the present study, we investigated the effects of complement C3 on NBO‐treated ICH patients and model mice, and the underlying mechanism of NBO therapy in ICH‐mediated brain injury. Results Hemorrhagic injury resulted in the high plasma C3 levels in ICH patients, and the plasma C3 levels were closely related to hemorrhagic severity and clinical outcomes after ICH. BO treatment alleviated neurologic impairments and rescued the hemorrhagic‐induced increase in plasma C3 levels in ICH patients and model mice. Moreover, the results indicated that NBO exerted its protective effects of on brain injury after ICH by downregulating the expression of C3 in microglia and alleviating microglia‐mediated synaptic pruning. Conclusions Our results revealed that NBO exerts its neuroprotective effects by reducing C3‐mediated synaptic pruning, which suggested that NBO therapy could be used for the clinical treatment of ICH.
Higenamine (HG) is an active compound derived from Aconiti root with a cardiotonic effect. It has been approved by the Chinese SFDA for clinical trials due to its effect as a potent inotropic and chronotropic agent in the heart. However, the direct mode of action of HG on cardiac electrophysiology is unclear.The experiments were performed at both cell levels and the isolated organ. The major cardiac ion currents and the action potential duration (APD) were measured using patch-clamps in single guinea-pig left ventricular myocytes. ECG was recorded in isolated guinea pig hearts.In the left ventricular myocytes, HG increased ICa-L and IKs in concentration- and voltage-dependent manners in the left ventricular myocytes. It potentiated the ICa-L and IKs simultaneously for synchronization. The EC50 values were 0.27 μM and 0.64 μM for the ICa-L and IKs, respectively. HG (0.1 μM, 0.5 μM and 1 μM) had no effect on the IKr and INa. HG slightly prolonged APD at lower concentrations, and shortened the APD at higher concentrations. HG can induce the delayed after depolarization (DAD), which showed some pro-arrhythmic effect. In the isolated perfused heart, HG increased the heart rate via an action on the sinoatrial node cells, but did not induce cardiac arrhythmias, even at high concentrations. The EC50 value for the sinoatrial node that controls the heart rate was 0.13 μM. The sinoatrial node cells appeared to be more sensitive than ventricular myocytes to HG. The effects of HG on ventricular cells and sinoatrial node cells were both mediated through stimulation of β1-AR.We show for the first time that HG produced a predominant action on the sinoatrial node. HG appears to control the cardiac electrophysiology through its predominant effect on the sinoarial node cells, without induction of the ectopic activity that causes cardiac arrhythmias. Thus, HG might be useful for the treatment of bradycardia.
To further understand the mode of action and pharmacokinetics of lisinopril, the binding interaction of lisinopril with bovine serum albumin (BSA) under imitated physiological conditions (pH 7.4) was investigated using fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD) and molecular docking methods. The results showed that the fluorescence quenching of BSA near 338 nm resulted from the formation of a lisinopril-BSA complex. The number of binding sites (n) for lisinopril binding on subdomain IIIA (site II) of BSA and the binding constant were ~ 1 and 2.04 × 10(4) M(-1), respectively, at 310 K. The binding of lisinopril to BSA induced a slight change in the conformation of BSA, which retained its α-helical structure. However, the binding of lisinopril with BSA was spontaneous and the main interaction forces involved were van der Waal's force and hydrogen bonding interaction as shown by the negative values of ΔG(0), ΔH(0) and ΔS(0) for the binding of lisinopril with BSA. It was concluded from the molecular docking results that the flexibility of lisinopril also played an important role in increasing the stability of the lisinopril-BSA complex.
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