Biology subjects

Shang, Y.

Publications and source records attributed to Shang, Y..

43 records · Page 3Linked to original sources

bioRxiv2019

Specific gyrA gene mutations correlate with high prevalence of discordant levofloxacin resistance in Mycobacterium tuberculosis isolates from Beijing, China

Although molecular diagnostics are highly sensitive in the diagnosis of fluroquinolone (FQ)-resistant tuberculosis (TB), the discordant results with the sequential phenotypic drug susceptibility testing (DST) invariably occur. To investigate the prevalence and the cause of discordant results between molecular and phenotypic DST for levofloxacin (LFX), the cases who were determined to be LFX-susceptible using the phenotypic DST but LFX-resistant using the MeltPro assay were retrospectively reviewed in Beijing, China. We measured LFX minimal inhibitory concentrations (MICs) using Middlebrook 7H9 broth. Sanger sequencing was used to determine genotypic characteristics of discordant isolates. Between January and December 2018, 126 (22.1%) out of 571 smear-positive TB patients were identified as LFX-resistant TB by MeltPro assay. Among the 126 LFX-resistant TB, there were 34 isolates identified as LFX-susceptible TB by phenotypical DST. This result demonstrated a discordance prevalence of 27.0%. LFX MICs were majorly centered around the critical concentration, and 7 (21.2%) and 13 (39.4%) had MICs of 2.0 mg/l and 4.0 mg/l, respectively. The most prevalent mutations conferring discordant LFX resistance were the amino acid substitutions of Ser to Leu in 90 codon (13, 39.4%) and Asp to Ala in 94 codon of gyrA (11, 33.3mg/l belonged to Ala90Val and Asp94Ala group. In conclusion, our data demonstrate that more than one quarter of LFX-resistant isolates by molecular method are susceptible to LFX using the phenotypic DST. The high prevalence of discordant LFX resistance is majorly due to the isolates with specific mutations within gyrA gene conferring proximity of MICs to the critical concentration.

microbiology↗

bioRxiv2019

Patterned Neuronal Activities Dictate Cell Type-specific Axon Regeneration

Why closely related neuronal types differ in their axon regenerative abilities remains elusive. Here, we demonstrate gliotransmission determines such a difference in Drosophila larval sensory neurons. Axotomy activates ensheathing glia, which signal to regenerative neurons through the gliotransmitter adenosine, to mount regenerative programs including neuronal activity and Ras. Surprisingly, ensheathing glia do not signal to non-regenerative neurons. Such neuronal type-specific responses to gliotransmission result from specific expression of adenosine receptors in regenerative neurons. Disrupting gliotransmission impedes regeneration of regenerative neurons. Strikingly, reconstitution of gliotransmission in non-regenerative neurons enables them to regenerate. Furthermore, activation of an adenosine receptor ortholog in adult mice promotes both regeneration and survival of retinal ganglion cells, uncovering a conserved pro-regenerative role of adenosine receptors. Our studies demonstrate gliotransmission as a novel mechanism by which glia instruct axon regeneration, with neuronal type-specificity, and suggest targeting purinergic signaling as a new strategy for mammalian central nervous system repair. HIGHLIGHTSEnsheathing glia differentially interact with Drosophila sensory neuron types through gliotransmission Gliotransmission mounts axon regenerative programs in selective neuronal types Neuronal firing pattern but not overall excitability dictates axon regeneration outcome Adenosine receptor activation in adult mice promotes both regeneration and survival of RGCs

neuroscience↗

bioRxiv2019

Novel Pure αVβ3 Integrin Antagonists That Do Not Induce Receptor Extension, Prime the Receptor, or Enhance Angiogenesis at Low Concentrations

The integrin V{beta}3 receptor has been implicated in several important diseases, but no V{beta}3 antagonists are approved for human therapy. One possible limitation of current small-molecule antagonists is their ability to induce a major conformational change in the receptor that induces it to adopt a high-affinity ligand-binding state. In response, we used structural inferences from a pure peptide antagonist to design the small-molecule pure antagonists TDI-4161 and TDI-3761. Both compounds inhibit V{beta}3-mediated cell adhesion to V{beta}3 ligands, but do not induce the conformational change as judged by antibody binding, electron microscopy, X-ray crystallography, and receptor priming studies. Both compounds demonstrated the favorable property of inhibiting bone resorption in vitro, supporting potential value in treating osteoporosis. Neither, however, had the unfavorable property of the V{beta}3 antagonist cilengitide of paradoxically enhancing aortic sprout angiogenesis at concentrations below its IC50, which correlates with cilengitides enhancement of tumor growth in vivo.\n\nSignificance StatementV{beta}3 is a potential therapeutic target for several important human diseases, but there are currently no V{beta}3 antagonists approved for human therapy. Current candidates are primarily based on the Arg-Gly-Asp (RGD) motif and act as partial agonists in that they induce V{beta}3 to undergo a conformational change that converts it into a high-affinity ligand-binding state. We have used structure-guided design to produce pure small-molecule V{beta}3 antagonists that do not induce the conformational change as judged by protein crystallography, electron microscopy, and receptor priming. These compounds inhibit V{beta}3-mediated bone resorption in vitro, but unlike the partial agonist cilengitide, do not enhance angiogenesis at low doses, a property that correlates with low-dose cilengitides enhancement of tumor growth in vivo. These pure V{beta}3 antagonists can help define V{beta}3s role in animal models. If they demonstrate benefits over partial agonists in these model systems, they may be appropriate to consider for human therapy.

pharmacology and toxicology↗

bioRxiv2018

ALV-J and REV synergistically activate a new oncogene of KIAA1199 via NF-κB and EGFR signaling regulated by miR-147

The tumorigenesis is the result of the accumulation of multiple oncogenes and tumor suppressor genes changes. Co-infection of avian leucosis virus subgroup J (ALV-J) and reticuloendotheliosis virus (REV), as two oncogenic retroviruses, showed synergistic pathogenic effects characterized by enhanced tumor initiation and progression. The molecular mechanism underlying synergistic effects of ALV-J and REV on the neoplasia remains unclear. Here, we found co-infection of ALV-J and REV enhanced the ability of virus infection, increased viral life cycle, maintained cell survival and enhanced tumor formation. We combined the high-throughput proteomic readout with a large-scale miRNA screening to identify which molecules are involved in the synergism. Our results revealed co-infection of ALV-J and REV activated a latent oncogene of KIAA1199 and inhibited the expression of tumor suppressor miR-147. Further, enhanced KIAA1199, down-regulated miR-147, activated NF-{kappa}B and EGFR were demonstrated in co-infected tissues and tumor. Mechanistically, we showed ALV-J and REV synergistically enhanced KIAA1199 by activation of NF-{kappa}B and EGFR signalling pathway, and the suppression of tumor suppressor miR-147 was contributed to maintain the NF-{kappa}B/KIAA1199/EGFR pathway crosstalk by targeting the 3UTR region sequences of NF-{kappa}B p50 and KIAA1199. Our results contributed to the understanding of the molecular mechanisms of viral synergistic tumorgenesis, which provided the evidence that suggested the synergistic actions of two retroviruses could result in activation of latent pro-oncogenes.\n\nAuthor summaryThe tumorigenesis is the result of the accumulation of multiple oncogenes and tumor suppressor genes changes. Co-infection with ALV-J and REV showed synergistic pathogenic effects characterized by enhanced tumor progression, however, the molecular mechanism on the neoplasia remains unclear. Our results revealed co-infection of ALV-J and REV promotes tumorigenesis by both induction of a latent oncogene of KIAA1199 and suppression of the expression of tumor suppressor miR-147. Mechanistic studies revealed that ALV-J and REV synergistically enhance KIAA1199 by activation of NF-{kappa}B and EGFR signalling pathway, and the suppression of tumor suppressor miR-147 was contributed to maintain the NF-{kappa}B/KIAA1199/EGFR pathway crosstalk by targeting the 3UTR region sequences of NF-{kappa}B p50 and KIAA1199. These results provided the evidence that suggested the synergistic actions of two retroviruses could result in activation of latent pro-oncogenes, indicating the potential preventive target and predictive factor for ALV-J and REV induced tumorigenesis.

molecular biology↗

bioRxiv2018

Specific Eph Receptor-Cytoplasmic Effector Signaling Mediated by SAM-SAM Domain Interactions

The Eph receptor tyrosine kinase (RTK) family is the largest subfamily of RTKs playing critical roles in many developmental processes such as tissue patterning, neurogenesis and neuronal circuit formation, angiogenesis, etc. How the 14 Eph proteins, via their highly similar cytoplasmic domains, can transmit diverse and sometimes opposite cellular signals upon engaging ephrins is a major unresolved question. Here we systematically investigated the bindings of each SAM domain of Eph receptors to the SAM domains from SHIP2 and Odin, and uncover a highly specific SAM-SAM interaction-mediated cytoplasmic Eph-effector binding pattern. Comparative X-ray crystallographic studies of several SAM-SAM heterodimer complexes, together with biochemical and cell biology experiments, not only revealed the exquisite specificity code governing Eph/effector interactions but also allowed us to identify SAMD5 as a new Eph binding partner. Finally, these Eph/effector SAM heterodimer structures can explain numerous Eph SAM mutations identified in patients suffering from cancers and other diseases.

biophysics↗

bioRxiv2017

Down-regulation of LRIG1 by miR-20a modulates gastric cancer multidrug resistance

Multidrug resistance (MDR) significantly restricts the clinical efficacy of gastric cancer (GC) chemotherapy, and it is critical to search novel targets to predict and overcome MDR. Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) has been proved to be correlated with drug resistance in several cancers. The present study revealed that LRIG1 was overexpressed in chemo-sensitive GC tissues and decreased expression of LRIG1 predicted poor survival in GC patients. We observed that up-regulation of LRIG1 enhanced chemo-sensitivity in GC cells. Interestingly, miR-20a, which was overexpressed in GC MDR cell lines and tissues, was identified to regulate LRIG1 expression by directly targeting its 3'untranslated region. We also found that inhibition of miR-20a suppressed GC MDR, and up-regulation showed opposite effects. Moreover, we demonstrated that the miR-20a/LRIG1 axis regulated GC cell MDR through EGFR mediated PI3K/AKT and MAPK/ERK signaling pathways. Finally, LRIG1 expression in human GC tissues is inversely correlated with miR-20a and EGFR. Taken together, the newly identified miR-20a/LRIG1/EGFR link provides insight into the MDR process of GC, and targeting this axis represents a novel potential therapeutic strategy to block GC chemo-resistance.

cancer biology↗

bioRxiv2017

Gene expression profiling reveals U1 snRNA regulates cancer gene expression

U1 small nuclear RNA (U1 snRNA), as one of the most abundant noncoding RNA in eukaryotic cells plays an important role in splicing of pre-mRNAs. Compared to other studies which have focused on the primary function of U1 snRNA and the neurodegenerative diseases caused by the abnormalities of U1 snRNA, this study is to investigate how the U1 snRNA over-expression affects the expression of genes on a genome-wide scale. In this study, we built a model of U1 snRNA over-expression in a rat cell line. By comparing the gene expression profiles of U1 snRNA over-expressed cells with those of their controls using the microarray experiments, 916 genes or loci were identified significantly differentially expressed. These 595 up-regulated genes and 321 down-regulated genes were further analyzed using the annotations from the GO terms and the KEGG database. As a result, three of 12 enriched pathways are well-known cancer pathways, while nine of them were associated to cancers in previous studies. The further analysis of 73 genes involved in 12 pathways suggests that U1 snRNA regulates cancer gene expression. The microarray data with ID GSE84304 is available in the NCBI GEO database.

cancer biology↗