Biology subjects

Ni, Z.

Publications and source records attributed to Ni, Z..

42 records · Page 3Linked to original sources

bioRxiv2019

Regulation of transcription termination by FUS and TDP-43

The carboxy-terminal domain (CTD) of the RNA polymerase II (RNAPII) subunit POLR2A is a platform for modifications specifying the recruitment of factors that regulate transcription, mRNA processing, and chromatin remodelling. We previously found that symmetrical dimethylation (me2s) of a CTD Arginine residue (R1810 in human) causes recruitment of the Tudor domain of SMN, which interacts with Senataxin. SMN is mutated in spinal muscular atrophy (SMA), and Senataxin is sometimes mutated in Amyotrophic Lateral Sclerosis (ALS). R1810me2s and SMN, like Senataxin, are important for resolving R-loops (DNA:RNA hybrids) at transcription terminators. FUS and TDP-43 (TARDBP) are DNA/RNA binding proteins that are sometimes mutated in ALS and FTD (Frontotemporal dementia). Here we show that TDP-43 and, to some extent, FUS are recruited by the R1810me2s-SMN pathway. Defects in FUS and TDP-43 recruitment influence RNAPII termination and R-loop accumulation, leading to elevated DNA damage at terminators that may contribute to neurodegenerative disorders like ALS and FTD.

molecular biology↗

bioRxiv2019

A web-server framework to explore and visualize large genomic variation data in lab and its applications to wheat and its progenitors

BackgroundThe cost of high-throughput sequencing is rapidly decreasing, allowing researchers to investigate genomic variations across hundreds or even thousands of samples in the post-genomic era. The management and exploration of these large-scale genomic variation data require programming skills. The public genotype querying databases of many species are usually centralized and implemented independently, making them difficult to update with new data over time. Currently, there is a lack of a widely used framework for setting up user-friendly web servers for exploring new genomic variation data in diverse species. ResultsHere, we present SnpHub, a Shiny/R-based server framework for retrieving, analysing and visualizing the large-scale genomic variation data that be easily set up on any Linux server. After a pre-building process based on the provided VCF files and genome annotation files, the local server allows users to interactively access SNPs/INDELs and annotation information by locus or gene and for user-defined sample sets through a webpage. Users can freely analyse and visualize genomic variations in heatmaps, phylogenetic trees, haplotype networks, or geographical maps. Sample-specific sequences can be accessed as replaced by SNPs/INDELs. ConclusionsSnpHub can be applied to any species, and we build up a SnpHub portal website for wheat and its progenitors based on published data in present studies. SnpHub and its tutorial are available as http://guoweilong.github.io/SnpHub/.

bioinformatics↗

bioRxiv2019

Dosage-sensitivity of human transcription factor genes

Changes in the copy number of protein-coding genes would lead to detrimental effects if the consequent changes in protein concentration disrupt essential cellular functions. Large-scale genomic studies have identified thousands of dosage-sensitive genes in human genome. We are interested in the dosage-sensitivity of transcription factor (TF) genes whose products are essential for the growth, division and differentiation of cells by regulating the expression of the genetic information encoded in the genome. We first surveyed the enrichment of human TF genes in four recently curated datasets of dosage-sensitive genes, including the haploinsufficient genes identified by a large-scale genomic study, the haploinsufficient genes predicted by a machine learning approach, the genes with conserved copy number across mammals, and the ohnologs. Then we selected the dosage-sensitive genes that are present in all the four dataset and regarded them as the most reliable dosage-sensitive genes, and the genes that are absent from any one of the four datasets as the most reliable dosage-insensitive genes, and surveyed the enrichments of TFs genes in these two datasets. A large number of TF genes were found to be dosage-insensitive, which is beyond the expectation based on the role of TFs. In spite of this, the likeness of TF genes to be dosage-sensitive were supported by five datasets, with the conserved-copy-number genes as the exception. The nuclear receptors are the only one family of TFs whose dosage-sensitivity was consistently supported by all the six datasets. In addition, we found that TF families with very few members are also more likely to be dosage-sensitive while the largest TF family, C2H2-ZF, are most likely dosage-insensitive. The most extensively studied TFs, p53, are not special in dosage-sensitivity. They are significantly enriched in only three datasets. We also confirmed that dosage-sensitive genes generally have long coding sequences, high expression levels and experienced stronger selective pressure. Our results indicate some TFs function in a dose-dependent manner while some other not. Gene dosage changes in some TF families like nuclear receptor would result in disease phenotypes while the effects of such changes in some TFs like C2H2-ZF would be mild.

genetics↗

bioRxiv2018

Genome-wide association study identifies common genetic risk factors for alcohol, heroin and methamphetamine dependence

BackgroundCommon molecular and cellular foundations underlie different types of substance dependence (SD). However direct evidence for common genetic factors of SD is lacking. Here we aimed to identify specific genetic variants that are shared between alcoholism, heroin and methamphetamine dependence.\n\nMethodsWe first conducted a combined case-control genome-wide association analysis (GWAS) of 521 alcoholic, 1,026 heroin and 1,749 methamphetamine patients and 2,859 healthy controls. We then replicated the significant loci using an independent cohort (146 alcoholic, 1,045 heroin, 763 methamphetamine and 1,904 controls). Second, we examined the genetic effects of these identified SNPs on gene expression, addiction characteristics and brain images (gray and white matter). Furthermore, we investigated the effects of these genetic variants on addiction behaviors using self-administration rat models.\n\nResultsWe identified and validated four genome-wide significant loci in the combined cohorts in the discovery stage: ADH1B rs1229984 (P=6.45x10-10), ANKS1B rs2133896 (P=4.09x10-8), AGBL4 rs147247472 (P=4.30x10-8) and CTNNA2 rs10196867 (P=4.67x10-8). Association results for each dependence group showed that ADH1B rs1229984 was only associated with alcoholism, while the other three loci were associated with heroin, methamphetamine addiction and alcoholism respectively. Variants that were strongly linked to rs2133896 affected ANKS1B gene expression, heroin use frequency and interacted with heroin dependence to affect gray matter of the left calcarine and white matter of the right superior longitudinal fasciculus. In addition, the reduced anks1b expression in the ventral tegmental area increased addiction vulnerability for heroin and methamphetamine in self-administration rat models.\n\nConclusionOur findings revealed several novel genome-wide significant SNPs and genes that synchronously affected the vulnerability and phenotypes for alcoholism, heroin and MA dependence. These findings could shed light on the root cause and the generalized vulnerability for SD.

genomics↗

bioRxiv2018

Desiccation Does Not Drastically Increase the Accessibility of Foreign DNA to the Nuclear Genomes: Evidence from the Frequency of Endosymbiotic DNA Transfer

Horizontal gene transfer (HGT) is a widely accepted force in the evolution of prokaryotic genomes. However, in eukaryotes, it is still in hot debate. Some bdelloid rotifers that are resistant to extreme desiccation and radiation were reported to have a very high level of HGTs. However, a similar report in another resistant invertebrate, tardigrades, has been mired in controversy. The DNA double-strand breaks (DSBs) induced by prolonged desiccation have been postulated to open the gateway of nuclear genome for foreign DNA integration and thus facilitate the HGT process. If so, the rate of endosymbiotic DNA transfer should also be enhanced. We first surveyed the abundance of nuclear mitochondrial DNAs (NUMTs) and nuclear plastid DNAs (NUPTs) in three groups of eukaryotes that are extremely resistant to desiccation, bdelloid rotifers, A. vaga and A. ricciae, tardigrades, H. dujardini and R. varieornatus, and the resurrection plants, D. hygrometricum and S. tamariscina. Excessive NUMTs or NUPTs have not been detected. Furthermore, we compared nine groups of desiccation-tolerant organisms with their desiccation-sensitive relatives but did not find significant difference in the NUMT/NUPT contents. Desiccation could induce DSBs, but it unlikely dramatically increase the frequency of foreign sequence integration in most eukaryotes. Only in the nuclear genomes enriched in repetitive sequences, the DSBs are predominantly repaired by non-homologous end joining (NHEJ) and desiccation-induced DSBs is possible to enhance the integration of foreign sequences into nuclear genome for some degree.

evolutionary biology↗

bioRxiv2018

Crosstalk between RNA Pol II C-Terminal Domain Acetylation and Phosphorylation via RPRD Proteins

Post-translational modifications of the RNA polymerase II C-terminal domain (CTD) coordinate the transcription cycle. Crosstalk between different modifications is poorly understood. Here, we show how acetylation of lysine residues at position 7 of characteristic heptad repeats (K7ac)--only found in higher eukaryotes--regulates phosphorylation of serines at position 5 (S5p), a conserved mark of polymerases initiating transcription. We identified the regulator of pre-mRNA domain-containing (RPRD) proteins as reader proteins of K7ac. K7ac enhanced CTD peptide binding to the CTD-interacting domain (CID) of RPRD1A and RPRD1B proteins in isothermal calorimetry and molecular modeling experiments. Deacetylase inhibitors increased K7ac- and decreased S5-phosphorylated polymerases, consistent with acetylation-dependent S5 dephosphorylation by an RPRD-associated S5 phosphatase. Consistent with this model, RPRD1B knockdown increased S5p, but enhanced K7ac, indicating RPRD proteins recruit K7 deacetylases, including HDAC1. We also report auto-regulatory crosstalk between K7ac and S5p via RPRD proteins and their interactions with acetyl- and phospho-eraser proteins.

molecular biology↗