Biology subjects

Tang, L.

Publications and source records attributed to Tang, L..

6 recordsLinked to original sources

bioRxiv2018

Integrative analysis of Zika virus genome RNA structure reveals critical determinants of viral infectivity

Since its outbreak in 2007, Zika virus (ZIKV) has become a global health threat that causes severe neurological conditions. Here we perform a comparative in vivo structural analysis of the RNA genomes of two ZIKV strains to decipher the regulation of their infection at the RNA level. Our analysis identified both known and novel functional RNA structural elements. We discovered a functional long-range intramolecular interaction specific for the Asian epidemic strains, which contributes to their infectivity. Our findings illuminate the structural basis of ZIKV regulation and provide a rich resource for the discovery of RNA structural elements that are important for ZIKV infection.

molecular biology↗

bioRxiv2018

Dynamic Regulation of RNA Structure in Mammalian Cells

RNA structure is intimately connected to each step of gene expression. Recent advances have enabled transcriptome-wide maps of RNA secondary structure, termed RNA structuromes. However, previous whole-cell analyses lacked the resolution to unravel the dynamic regulation of RNA structure across subcellular states. Here we reveal the RNA structuromes in three compartments -- chromatin, nucleoplasm and cytoplasm. The cytotopic structuromes substantially expand RNA structural information, and enable detailed investigation of the central role of RNA structure in linking transcription, translation, and RNA decay. Through comparative structure analysis, we develop a resource to visualize the interplay of RNA-protein interactions, RNA chemical modifications, and RNA structure, and predict both direct and indirect reader proteins of RNA modifications. We validate the novel role of the RNA binding protein LIN28A as an N6-methyladenosine (m6A) modification \"anti-reader\". Our results highlight the dynamic nature of RNA structures and its functional significance in gene regulation.

molecular biology↗

bioRxiv2018

Multi-omics analysis of AML cells treated with azacitidine reveals highly variable cell surface proteome remodeling

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are diseases of abnormal hematopoietic differentiation with aberrant epigenetic alterations. Azacitidine (AZA) is a DNA methyltransferase inhibitor (DNMTi) widely used to treat MDS and AML, yet the impact of AZA on the cell surface proteome has not been defined. To identify potential therapeutic targets for use in combination with AZA in AML patients, we investigated the effects of AZA treatment on four AML cell lines (KG1a, HL60, HNT34, and AML193), representing different stages of differentiation. The effect of AZA treatment on these cell lines was characterized at three levels: the DNA methylome (methylation array), the transcriptome (gene expression array), and the cell surface proteome (glycoprotein capture with SILAC labeling). Untreated AML cell lines showed substantial overlap in their methylomes, transcriptomes, and cell surface proteomes. AZA treatment globally reduced DNA methylation in all cell lines, but changes in the transcriptome and surface proteome were subtle and differed among the cell lines. Transcriptome analysis identified five commonly up-regulated coding genes upon AZA treatment in all four cell lines, TRPM4 being the only gene encoding a surface protein, and surface proteomics analysis found no commonly regulated proteins. Gene Set Enrichment Analysis (GSEA) of differentially-regulated RNA and surface proteins showed a decrease in metabolism pathways and an increase in immune defense response pathways. As such, AZA treatment in four AML cell lines had diverse effects at the individual gene and protein level, but converged to regulation of metabolism and immune response at the pathway level. Given the heterogeneous response of AZA in the four cell lines at the gene and protein level, we discuss potential therapeutic strategies for combinations with AZA.

cancer biology↗

bioRxiv2018

Notch3 Promotes Prostate Cancer-Induced Bone Osteoblastic Metastasis in an MMP-3-Dependent Manner

Prostate cancer metastases primarily localize in the bone where they induce a unique osteoblastic response. Elevated Notch activity is associated with high-grade disease and metastasis. To address how Notch affects prostate cancer bone lesions, we manipulated Notch expression in mouse tibia xenografts and monitored tumor growth, lesion phenotype, and the bone microenvironment. Prostate cancer cell lines that induce mixed osteoblastic lesions in bone expressed 5-6 times more Notch3, than tumor cells that produce osteolytic lesions. Expression of active Notch3 (NICD3) in osteolytic tumors reduced osteolytic lesion area and enhanced osteoblastogenesis, while loss of Notch3 in osteoblastic tumors enhanced osteolytic lesion area and decreased osteoblastogensis. This was accompanied by a respective decrease and increase in the number of active osteoclasts and osteoblasts at the tumor-bone interface, without any effect on tumor proliferation. Conditioned medium from NICD3-expressing cells enhanced osteoblast differentiation and proliferation in vitro, while simultaneously inhibiting osteoclastogenesis. MMP-3 was specifically elevated and secreted by NICD3-expressing tumors, and inhibition of MMP-3 rescued the NICD3-induced osteoblastic phenotypes. Clinical osteoblastic bone metastasis samples had higher levels of Notch3 and MMP-3 compared to patient matched visceral metastases or osteolytic metastasis samples. We identified a Notch3-MMP-3 axis in human prostate cancer bone metastases that contributes to osteoblastic lesion formation by blocking osteoclast differentiation, while also contributing to osteoblastogenesis. These studies define a new role for Notch3 in manipulating the tumor microenvironment in bone metastases.

cancer biology↗

bioRxiv2017

ATRX, DAXX or MEN1 mutant pancreatic neuroendocrine tumors are a distinct alpha-cell signature subgroup

The most commonly mutated genes in pancreatic neuroendocrine tumors (PanNETs) are ATRX, DAXX, and MEN1. Little is known about the cells-of-origin for non-functional neuroendocrine tumors. Here, we genotyped 64 PanNETs for mutations in ATRX, DAXX, and MEN1 and found 37 tumors (58%) carry mutations in these three genes (A-D-M mutant PanNETs) and this correlates with a worse clinical outcome than tumors carrying the wild-type alleles of all three genes (A-D-M WT PanNETs). We performed RNA sequencing and DNA-methylation analysis on 33 randomly selected cases to reveal two distinct subgroups with one group consisting entirely of A-D-M mutant PanNETs. Two biomarkers differentiating A-D-M mutant from A-D-M WT PanNETs were high ARX gene expression and low PDX1 gene expression with PDX1 promoter hyper-methylation in the A-D-M mutant PanNETs. Moreover, A-D-M mutant PanNETs had a gene expression signature related to that of alpha cells (pval < 0.009) of pancreatic islets including increased expression of HNF1A and its transcriptional target genes. This gene expression profile suggests that A-D-M mutant PanNETs originate from or transdifferentiate into a distinct cell type similar to alpha cells.

cancer biology↗

bioRxiv2017

Demoralization among cancer patients in mainland China: validity of the Demoralization Scale (DS)

Demoralization, characterized by hopelessness, helplessness, and loss of meaning and purpose, reflects existential distress. The objectives is To assess the validity of a Mainland Chinese versions of the demoralization scale (MC-DS) for using with Mainland Chinese cancer patients. In-patients sequentially recruited from a specialist tertiary-level cancer hospital in Beijing between January 2016-April 2016 completed Demoralization Scale, (DS) Patient Health Questionnaire-9 (PHQ-9), Revised Life Orientation Test (CLOT-R), Beck Hopelessness Scale (BHS), and provided sociodemographic and clinical information. We determined DS factor structure and convergent and divergent validity. 296/424 (70.0%) participants reported mean DS score=30.42(SD=13.00). EFA identified 3-factors explaining 21.4%, 17.8%, and 10.6% respectively of observed variance. Respective Cronbach Alphas were 0.88, 0.84, and 0.64 (0.90 full-scale). Convergent was shown by PHQ-9 scores correlating with Factor 2 (r=0.606), and BHS and C-LOT-R scores correlating (r=0.632,r=0.407 respectively) with Factor 1. Dichotomizing demoralization (high >30, low[less double equals]30) cross-tabulated against PHQ-9 score (mood) scores revealed 47% of patients exceeded demoralization cut-off, 60% of whom were not depressed. Using mean value{+/-}SD indicated demoralization cutoffs at <17.4 (low), 17.4-43.4 (medium) and >43.4 (high). Overall 71% met criteria for medium demoralization, and 15% for high demoralization. Sixty percent of all medium demoralization patients were not depressed, but only 5% of high demoralization patients were not depressed. The conclusion is that the Mainland Chinese Demoralization Scale is useful for detecting mild-to-moderate demoralization in cancer patients but at higher scores has poor specificity against depression.

epidemiology↗