Biology subjects

Ye, L.

Publications and source records attributed to Ye, L..

6 recordsLinked to original sources

bioRxiv2018

Niacin fine-tunes energy homeostasis through canonical GPR109A signaling

Niacin has long been considered as a high-potency drug for beneficially treating lipid abnormalities, however, its anti-atherosclerotic effects have been challenged by recent studies. Here, we demonstrated that oral supplementation of niacin resulted in a significant reduction in body weight and fat mass without affecting food intake in high-fat diet-fed wild-type mice, but not in GPR109A-defeicient mice. Further investigation showed that niacin challenge led to a remarkable inhibition of hepatic lipogenesis via a GPR109A-dependent ERK1/2/AMPK pathway. Additionally, we demonstrated that niacin treatment stimulated thermogenesis in brown adipose tissue by induction of thermogenic genes via GPR109A. Moreover, we observed that mice exposed to niacin exhibited a dramatic decrease in intestinal absorption of fatty acids. Together, our data demonstrate that acting on GPR109A, niacin shows the potential to maintain energy homeostasis by fine-tuning hepatic lipogenesis, BAT/beige thermogenesis and intestinal fat absorption, representing a potential approach to the treatment of lipid abnormalities.

cell biology↗

bioRxiv2018

A chromosome-scale assembly of the sorghum genome using nanopore sequencing and optical mapping

The advent of long-read sequencing technologies has greatly facilitated assemblies of large eukaryotic genomes. In this paper, Oxford Nanopore sequences generated on a MinION sequencer were combined with BioNano Genomics Direct Label and Stain (DLS) optical maps to generate a chromosome-scale de novo assembly of the repeat-rich Sorghum bicolor Tx430 genome. The final hybrid assembly consists of 29 scaffolds, encompassing in most cases entire chromosome arms. It has a scaffold N50 value of 33.28Mbps and covers >90% of Sorghum bicolor expected genome length. A sequence accuracy of 99.67% was obtained in unique regions after aligning contigs against Illumina Tx430 data. Alignments showed that 99.4% of the 34,211 public gene models are present in the assembly, including 94.2% mapping end-to-end. Comparisons of the DLS optical maps against the public Sorghum Bicolor v3.0.1 BTx623 genome assembly suggest the presence of substantial genomic rearrangements whose origin remains to be determined.

genomics↗

bioRxiv2017

Direct in vivo mapping of functional suppressors in glioblastoma genome

Glioblastoma (GBM) is one of the deadliest cancers, with limited effective treatments and single-digit five-year survival 1-7. A causative understanding of genetic factors that regulate GBM formation is of central importance 8-19. However, a global, quantitative and functional understanding of gliomagenesis in the native brain environment has been lacking due to multiple challenges. Here, we developed an adeno-associated virus (AAV) mediated autochthonous CRISPR screen and directly mapped functional suppressors in the GBM genome. Stereotaxic delivery of an AAV library targeting significantly mutated genes into fully immunocompetent conditional Cas9 mice robustly led to gliomagenesis, resulting in tumors that recapitulate features of human GBM. Targeted capture sequencing revealed deep mutational profiles with diverse patterns across mice, uncovering in vivo roles of previously uncharacterized factors in GBM such as immune regulator B2m, zinc finger protein Zc3h13, transcription repressor Cic, epigenetic regulators Mll2/3 and Arid1b, alongside canonical tumor suppressors Nf1 and Pten. Comparative cancer genomics showed that the mutation frequencies across all genes tested in mice significantly correlate with those in human from two independent patient cohorts. Co-mutation analysis identified frequently co-occurring driver combinations, which were validated using AAV minipools, such as Mll2, B2m-Nf1, Mll3-Nf1 and Zc3h13-Rb1. Distinct from Nf1-oncotype tumors, Rb1-oncotype tumors exhibit undifferentiated histopathology phenotype and aberrant activation of developmental reprogramming signatures such as Homeobox gene clusters. The secondary addition of Zc3h13 or Pten mutations drastically altered the gene expression profiles of Rb1 mutants and rendered them more resistant to the GBM chemotherapeutic temozolomide. Our study provides a systematic functional landscape of GBM suppressors directly in vivo, opening new paths for high-throughput molecular mapping and cancer phenotyping.

systems biology↗

bioRxiv2017

Pooled AAV-CRISPR Screen with Targeted Amplicon Sequencing

High-resolution, high-throughput direct in vivo screening of functional genetic factors in native tissues has long been challenging. Adeno-associated viruses (AAV) are powerful carriers of transgenes and have been shown to mediate efficient genome editing in various organs in mice. Here, we developed a new technological approach, Pooled AAV-CRISPR Screen with Targeted Amplicon Sequencing (PASTAS), and demonstrated its application for directly mapping functional cancer driver variants in the mouse liver in an autochthonous manner. Intravenous delivery of an AAV-CRISPR library targeting a set of the most frequently mutated tumor suppressor genes into fully immunocompetent conditional Cas9 knock-in mice consistently generated highly complex autochthonous liver tumors. The molecular landscapes of these genetically diverse tumors were mapped out by deep direct readout of Cas9-generated variants at predicted sgRNA cut sites using molecular inversion probe sequencing. Co-occurrence and correlation analyses as well as validation with lower complexity minipools further confirmed the potency of various co-mutated drivers. The PASTAS method can be applied to virtually any gene sets, any cancer types, or any type of in vivo genetic studies other than cancer.

systems biology↗

bioRxiv2017

Mapping in vivo genetic interactomics through Cpf1 crRNA array screening

Genetic interactions lay the foundation of biological networks in virtually all organisms. Due to the complexity of mammalian genomes and cellular architectures, unbiased mapping of genetic interactions in vivo is challenging. Cpf1 is a single effector RNA-guided nuclease that enables multiplexed genome editing using crRNA arrays. Here we designed a Cpf1 crRNA array library targeting all pairwise permutations of the most significantly mutated nononcogenes, and performed double knockout screens in mice using a model of malignant transformation as well as a model of metastasis. CrRNA array sequencing revealed a quantitative landscape of all single and double knockouts. Enrichment, synergy and clonal analyses identified many unpredicted drivers and co-drivers of transformation and metastasis, with epigenetic factors as hubs of these highly connected networks. Our study demonstrates a powerful yet simple approach for in vivo mapping of unbiased genetic interactomes in mammalian species at a phenotypic level.

genetics↗

bioRxiv2016

Chimeras Link to Tandem Repeats and Transposable Elements in Tetraploid Hybrid Fish

The formation of the allotetraploid hybrid lineage (4nAT) encompasses both distant hybridization and polyploidization processes. The allotetraploid offspring have two sets of sub-genomes inherited from both parental species and therefore it is important to explore its genetic structure. Herein, we construct a bacterial artificial chromosome library of allotetraploids, and then sequence and analyze the full-length sequences of 19 bacterial artificial chromosomes. Sixty-eight DNA chimeras are identified, which are divided into four models according to the distribution of the genomic DNA derived from the parents. Among the 68 genetic chimeras, 44 (64.71%) are linked to tandem repeats (TRs) and 23 (33.82%) are linked to transposable elements (TEs). The chimeras linked to TRs are related to slipped-strand mispairing and double-strand break repair while the chimeras linked to TEs are benefit from the intervention of recombinases. In addition, TRs and TEs are linked not only with the recombinations, but also with the insertions/deletions of DNA segments. We conclude that DNA chimeras accompanied by TRs and TEs coordinate a balance between the sub-genomes derived from the parents which reduces the genomic shock effects and favors the evolutionary and adaptive capacity of the allotetraploidization. It is the first report on the relationship between formation of the DNA chimeras and TRs and TEs in the polyploid animals.

genetics↗