Discovery and Characterization of Rubrinodin Provide Clues into the Evolution of Lasso Peptides.

Lasso peptides are unique natural products that comprise a class of ribosomally synthesized and post-translationally modified peptides. Their defining three-dimensional structure is a lariat knot, in which the C-terminal tail is threaded through a macrolactam ring formed between the N-terminal amino group and an Asp or Glu side chain (i.e., an isopeptide bond). Recent genome mining strategies have revealed various types of lasso peptide biosynthetic gene clusters and have thus redefined the known chemical space of lasso peptides. To date, over 20 different types of these gene clusters have been discovered, including several different clades from Proteobacteria. Despite the diverse architectures of these gene clusters, which may or may not encode various tailoring enzymes, most currently known lasso peptides are synthesized by two discrete clades defined by the presence of an ATP-binding cassette transporter or its absence and (sometimes) concurrent appearance of an isopeptidase, raising questions about their evolutionary history. Herein, we discovered and characterized the lasso peptide rubrinodin, which is assembled by a gene cluster encoding both an ATP-binding cassette transporter and an isopeptidase. Our bioinformatics analyses of this and other representative cluster types provided new clues into the evolutionary history of lasso peptides. Furthermore, our structural and biochemical investigations of rubrinodin permitted the conversion of this thermolabile lasso peptide into a more thermostable scaffold.

Learning and Investigation of the Role of Angiotensin-Converting Enzyme in Radiotherapy for Nasopharyngeal Carcinoma.

Ionizing radiation (IR) is an important treatment for nasopharyngeal carcinoma (NPC) that mainly kills tumor cells by producing large amounts of reactive oxygen species (ROS). Intracellular ROS levels affect the sensitivity of tumor cells to IR. Recently, angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin-converting enzyme (ACE) have been found to affect the intracellular levels of ROS. Therefore, we performed a health informatics assessment of ACE in the TCGA database. We explored the effect of ACE in NPC cells. We found that either knockdown of ACE or inhibition of ACE by enalaprilat could decrease ROS levels in NPC cells. Furthermore, knockdown of ACE or inhibition of ACE by enalaprilat could reduce IR-induced ROS levels. ACE knockdown or inhibition reduced IR-induced DNA damage and apoptosis. ACE overexpression increased the level of ROS in NPC cells and further increased sensitivity to IR. These findings indicate that ACE influences the effect of IR by regulating the level of ROS in NPC cells.

Protective effect of aspirin-triggered resolvin D1 on hepatic ischemia/reperfusion injury in rats: The role of miR-146b.

PURPOSE: Inflammatory responses play an important role in the tissue injury during liver ischemia/reperfusion (I/R). We previously reported that resolvin D1 (RvD1) administrated prior to hepatic I/R attenuates liver injury through inhibition of inflammatory response. In this study, we investigated the effects of the aspirin-triggered resolvin D1 (AT-RvD1) on hepatic I/R and the role of miR-146b in this process. METHODS: Partial warm ischemia was performed in the left and middle hepatic lobes of Sprague-Dawley rats for 1h, followed by 6h of reperfusion. Rats received either AT-RvD1 (5µg/kg), vehicle, or AT-RvD1+miR-146b antagomir by intravenous injection 30min before ischemia. Blood and tissue samples of the rats were collected after 6-h reperfusion. RESULTS: Pretreatment with AT-RvD1 significantly diminished I/R-induced elevations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and significantly blunted the histological injury of the liver. Moreover, AT-RvD1 significantly inhibited inflammatory response, as indicated by attenuations of TNF-α and myeloperoxidase levels. Reduced apoptosis, and increased survival rate were observed in the AT-RvD1 group compared with the control I/R group. AT-RvD1 pretreatment increased miR-146b expression in the liver of the rats with hepatic I/R. Administration of miR-146b antagomir impaired the effects of AT-RvD1 on hepatic I/R injury in rats. Downregulation of miR-146b inhibited TRAF6 and NF-κB expression in liver. CONCLUSIONS: Pre-administration of AT-RvD1 attenuates hepatic I/R injury partly through modulation of miR-146b.

Altered expression of stromal interaction molecule (STIM)-calcium release-activated calcium channel protein (ORAI) and inositol 1,4,5-trisphosphate receptors (IP3Rs) in cancer: will they become a new battlefield for oncotherapy?

The stromal interaction molecule (STIM)-calcium release-activated calcium channel protein (ORAI) and inositol 1,4,5-trisphosphate receptors (IP3Rs) play pivotal roles in the modulation of Ca(2+)-regulated pathways from gene transcription to cell apoptosis by driving calcium-dependent signaling processes. Increasing evidence has implicated the dysregulation of STIM-ORAI and IP3Rs in tumorigenesis and tumor progression. By controlling the activities, structure, and/or expression levels of these Ca(2+)-transporting proteins, malignant cancer cells can hijack them to drive essential biological functions for tumor development. However, the molecular mechanisms underlying the participation of STIM-ORAI and IP3Rs in the biological behavior of cancer remain elusive. In this review, we summarize recent advances regarding STIM-ORAI and IP3Rs and discuss how they promote cell proliferation, apoptosis evasion, and cell migration through temporal and spatial rearrangements in certain types of malignant cells. An understanding of the essential roles of STIM-ORAI and IP3Rs may provide new pharmacologic targets that achieve a better therapeutic effect by inhibiting their actions in key intracellular signaling pathways.

Effects of sevoflurane on leucine-rich repeat kinase 2-associated Drosophila model of Parkinson's disease.

Patients with Parkinson's disease (PD) often require surgery, and therefore may receive inhalation anesthesia. However, it is currently unknown whether inhalation anesthetics affect the prognosis of the disease. Leucine­rich repeat kinase 2 (LRRK2) genetic mutations are the most common cause of familial PD, contributing to ~39% of all cases in certain populations. The aim of the present study was to determine the effects of inhaled anesthetics on PD, by observing the influence of sevoflurane on a LRRK2­associated Drosophila model of PD. PD transgenic Drosophila overexpressing LRRK2 were generated by crossing flies expressing an LRRK2 upstream activation sequence, with tyrosine hydroxylase (TH)­Gal4 flies. Western blot analysis successfully verified that the transgenic Drosophila overexpressed LRRK2. Three days prior to eclosion, three genotypes of Drosophila were divided into four groups, and were exposed to air, 1, 2, or 3% sevoflurane, for 5 hours. Twenty­four hours after the exposure, the electrophysiological activities of the projection neurons (PN) in the brains of the Drosophila were recorded using a patch clamp. The locomotor activities were tested on days 5, 10, 15, 20, 25, 30, 35 and 40 following eclosion. The frequency of miniature excitatory synaptic currents (mEPSCs) obtained from the PNs of the TH­wild type LRRK2 (TH­WT) Drosophila brain, following exposure to air (1.60±0.05 Hz), was lower as compared with the wild type LRRK2 (WT) (2.51±0.07 Hz) and W1118 (2.41±0.10 Hz) Drosophila. After exposure to 1, 2 and 3% sevoflurane, the frequency of mEPSCs in the brains of the TH­WT group decreased to 0.82±0.04 Hz, 0.63±0.16 Hz and 0.55±0.04 Hz, respectively. The percentage decrease of the frequency of mEPSCs, from exposure to air to 1% sevoflurane, of the TH­WT group (48.32%±3.08%) was significantly higher, as compared with the WT (39.17%±1.42%) and W1118 (35.10%±2.66%) groups, and there was no statistical difference between the WT and W1118 groups. The transgenic TH­WT Drosophila presented an early decrease in locomotor ability, as compared with the WT and W1118 groups. Following a 5 hour exposure to sevoflurane, the percentage decrease of the climbing abilities of the TH­WT group, from exposure to air to 1% sevoflurane, were significantly lower, as compared with the WT and W1118 groups. In conclusion, sevoflurane had negative effects on the control W1118 flies, and also severely aggravated the prognosis of PD in the LRRK2­associated Drosophila model, through synaptic cholinergic deficits and impairment on locomotor abilities.

Butorphanol, a synthetic opioid, sensitizes ABCB1-mediated multidrug resistance via inhibition of the efflux function of ABCB1 in leukemia cells.

Multidrug resistance (MDR) remains a formidable challenge in the use of chemotherapy and represents a powerful obstacle to the treatment of leukemia. ATP-binding cassette subfamily B member 1 (ABCB1) is a recognized factor which causes MDR and is closely related to poor outcome and relapse in leukemia. Ongoing research concerning the strategy for inhibiting the abnormally high activity of the ABCB1 transporter is critically needed. In the present study, we sought to elucidate the interaction between ABCB1 transporter and butorphanol. Our results showed that butorphanol significantly antagonized ABCB1-mediated drug efflux and increased the intracellular drug concentration by inhibiting the transport activity of ABCB1 in leukemia cells. Mechanistic investigations demonstrated that butorphanol did not alter the protein expression or localization of ABCB1 in HL60/VCR and K562/ADR cells. Furthermore, homology modeling indicated that butorphanol could fit into the large drug-binding cavity of ABCB1 and form a binding conformation. In conclusion, butorphanol reversed the ABCB1-mediated MDR in leukemia cells by directly suppressing the efflux activity of ABCB1.