Biology subjects

Hua, N.

Publications and source records attributed to Hua, N..

7 recordsLinked to original sources

bioRxiv2024

Evolutionary trajectory of TRPM2 channel activation by adenosine diphosphate ribose and calcium

Ion channel activation upon ligand gating triggers a myriad of biological events and, therefore, evolution of ligand gating mechanism is of fundamental importance. TRPM2, a typical ancient ion channel, is activated by adenosine diphosphate ribose (ADPR) and calcium and its activation has evolved from a simple mode in invertebrates to a more complex one in vertebrates, but the evolutionary process is still unknown. Molecular evolutionary analysis of TRPM2s from more than 280 different animal species has revealed that, the C-terminal NUDT9-H domain has evolved from an enzyme to a ligand binding site for activation, while the N-terminal MHR domain maintains a conserved ligand binding site. Calcium gating pattern has also evolved, from one Ca2+-binding site as in sea anemones to three sites as in human. Importantly, we identified a new group represented by olTRPM2, which has a novel gating mode and fills the missing link of the channel gating evolution. We conclude that the TRPM2 ligand binding or activation mode evolved through at least three identifiable stages in the past billion years from simple to complicated and coordinated. Such findings benefit the evolutionary investigations of other channels and proteins.

evolutionary biology↗

bioRxiv2022

Co-targeting BCL-XL and MCL-1 with DT2216 and AZD8055 synergistically inhibits small-cell lung cancer growth without causing on-target toxicities in mice

Small-cell lung cancer (SCLC) is an aggressive malignancy with limited therapeutic options. The dismal prognosis in SCLC is in part associated with an upregulation of BCL-2 family anti-apoptotic proteins, including BCL-XL and MCL-1. Unfortunately, the currently available inhibitors of BCL-2 family anti-apoptotic proteins, except BCL-2 inhibitors, are not clinically relevant because of various on-target toxicities. We, therefore, aimed to develop an effective and safe strategy targeting these anti-apoptotic proteins with DT2216 (our platelet-sparing BCL-XL degrader) and AZD8055 (an mTOR inhibitor) to avoid associated on-target toxicities while synergistically optimizing tumor response. Through BH3 mimetic screening, we identified a subset of SCLC cell lines that is co-dependent on BCL-XL and MCL-1. After screening inhibitors of selected tumorigenic pathways, we found that AZD8055 selectively downregulates MCL-1 in SCLC cells and its combination with DT2216 synergistically killed BCL-XL/MCL-1 co-dependent SCLC cells, but not normal cells. Mechanistically, the combination caused BCL-XL degradation and suppression of MCL1 expression, and thus disrupted MCL-1 interaction with BIM leading to an enhanced apoptotic induction. In vivo, DT2216+AZD8055 combination significantly inhibited the growth of cell line-derived and patient-derived xenografts and reduced tumor burden accompanied with extended survival in a genetically-engineered mouse (GEM) model of SCLC without causing significant thrombocytopenia or other normal tissue injury. Thus, these preclinical findings lay a strong foundation for future clinical studies to test DT2216+mTOR inhibitor combination in a subset of SCLC patients whose tumors are co-driven by BCL-XL and MCL-1.

cancer biology↗

bioRxiv2022

Cryomilling Tethered Chromatin Conformation Capture reveal new insights into inter-chromosomal interactions

Traditional methods used to map the three-dimensional organization of chromatin in-situ generally involve chromatin conformation capture by formaldehyde crosslinking, followed by detergent solubilization and enzymatic digestion of DNA. Ligation of proximal DNA fragments followed by next generation sequencing (NGS) generates contact information that enables a global view of the chromatin conformation. Here, we explore the use of cryomilling to physically fragmentize the cells under cryogenic conditions to probe chromatin interactions in the cryomilled cell fragments by the tethered chromatin conformation capture (TCC). Our results show that cryomilling TCC (CTCC) can generate a global contact map similar to that obtained with in-situ Hi-C. This result suggests that summation of chromatin interactions mapped in individual subcellular fragments can reconstitute the global contact map of intact cells in an ensemble manner, paving the way for chromatin conformation analyses of solid tissue by CTCC. Compared with the conventional in-situ methods such as Hi-C, CTCC shows more uniform access to different subcompartments of the folded genome. On the other hand, most inter-chromosomal (trans) contacts are diminished or lost in CTCC except for a group of unique trans contacts that remain intact throughout the cryomilling and in- vitro crosslinking steps. These apparently ultra-stable trans interactions have much enhanced signal in CTCC due to the elimination of signals of most, presumably weak and transient trans interactions. Systematic and comparative analyses between CTCC and in-situ Hi-C provide further insights into the chromatin structure organization and reveal a generally unentangled chromosome interface and the existence of stable inter-chromosomal contacts that may represent intermingled inter-chromosomal interfaces.

genomics↗

bioRxiv2022

Identification of Piperlongumine (PL) as an new E3 ligase ligand to induce targeted protein degradation

PROteolysis Targeting Chimeras (PROTACs) are bifunctional molecules that degrade target proteins through recruiting E3 ligases. However, their application is limited in part because few E3 ligases can be recruited by known E3 ligase ligands. In this study, we identified piperlongumine (PL), a natural product, as a covalent E3 ligase recruiter, which induces CDK9 degradation when it is conjugated with SNS-032, a CDK9 inhibitor. The lead conjugate 955 can potently degrade CDK9 in a ubiquitin-proteasome-dependent manner and is much more potent than SNS-032 against various tumor cells in vitro. Mechanistically, we identified KEAP1 as the E3 ligase recruited by 955 to degrade CDK9 through a TurboID-based proteomics study, which was further confirmed by KEAP1 knockout and the nanoBRET ternary complex formation assay. In addition, PL-Ceritinib conjugate can degrade EML4-ALK fusion oncoprotein, suggesting that PL may have a broader application as a covalent E3 ligase ligand in targeted protein degradation.

cancer biology↗

bioRxiv2021

Mapping the nuclear microenvironment of genes at agenome-wide scale

The nuclear folding of chromosomes relative to nuclear bodies is an integral part of gene function. Here, we demonstrate that population-based modeling--from ensemble Hi-C data--can provide a detailed description of the nuclear microenvironment of genes and its role on gene function. We define the microenvironment by the subnuclear positions of genomic regions with respect to nuclear bodies, local chromatin compaction, and preferences in chromatin compartmentalization. These structural descriptors are determined in single cell models on a genome-wide scale, thereby revealing the structural variability between cells. We demonstrate that the structural microenvironment of a genomic region is linked to its functional potential in gene transcription, replication and chromatin compartmentalization. Some chromatin regions are distinguished by their strong preferences to a single microenvironment, due to associations to specific nuclear bodies in most cells. Other chromatin shows high structural variability, which is a strong indicator of functional heterogeneity. Moreover, we identify specialized nuclear microenvironments, which distinguish chromatin in different functional states and reveal a key role of nuclear speckles in chromosome organization. We demonstrate that our method produces highly predictive 3-dimensional genome structures, which accurately reproduce data from TSA-seq, DamID, GPSeq and super-resolution imaging. Thus, our method considerably expands the range of Hi-C data analysis and is widely applicable.

genomics↗

bioRxiv2017

Clustering enzymes using E.coli inner cell membrane as scaffold in metabolic pathway

Clustering enzymes in the same metabolism pathway is a natural strategy to enhance the productivity. Several systems have been designed to artificially cluster desired enzymes in the cell, such as synthetic protein scaffold and nucleic acid scaffold. However, these scaffolds require complicated construction process and have limited slots for target enzymes. Following this direction, we designed a scaffold system based on natural cell membrane. Target enzymes (FabZ, FabG, FabI and TesA in fatty acid synthesis II pathway) are anchored on the E.coli inner membrane, showing the enhanced metabolism flux without the requirement of the further artificial interactions to force the clustering. Furthermore, anchoring the enzymes on the membrane enhances the products exportation, which further increases the productivity. Together, the proposed system has potential applications in producing valuable biomaterials.

synthetic biology↗

bioRxiv2017

PGS: a dynamic and automated population-based genome structure software

Hi-C technologies are widely used to investigate the spatial organization of genomes. However, the structural variability of the genome is a great challenge to interpreting ensemble-averaged Hi-C data, particularly for long-range/interchromosomal interactions. We pioneered a probabilistic approach for generating a population of distinct diploid 3D genome structures consistent with all the chromatin-chromatin interaction probabilities from Hi-C experiments. Each structure in the population is a physical model of the genome in 3D. Analysis of these models yields new insights into the causes and the functional properties of the genomes organization in space and time. We provide a user-friendly software package, called PGS, that runs on local machines and high-performance computing platforms. PGS takes a genome-wide Hi-C contact frequency matrix and produces an ensemble of 3D genome structures entirely consistent with the input. The software automatically generates an analysis report, and also provides tools to extract and analyze the 3D coordinates of specific domains.

bioinformatics↗