Mapping Multi-factor-mediated Chromatin Interactions to Assess Dysregulation of Lung Cancer-related Genes

Studies on the lung cancer genome are indispensable for developing a cure for lung cancer.Whole-genome resequencing,genome-wide association studies,and transcriptome sequencing have greatly improved our understanding of the cancer genome.However,dysregulation of longrange chromatin interactions in lung cancer remains poorly described.To better understand the three-dimensional(3D)genomic interaction features of the lung cancer genome,we used the A549 cell line as a model system and generated high-resolution chromatin interactions associated with RNA polymerase II(RNAPII),CCCTC-binding factor(CTCF),enhancer of zeste homolog 2(EZH2),and histone 3 lysine 27 trimethylation(H3K27me3)using long-read chromatin interaction analysis by paired-end tag sequencing(ChIA-PET).Analysis showed that EZH2/H3K27me3-mediated interactions further repressed target genes,either through loops or domains,and their distributions along the genome were distinct from and complementary to those associated with RNAPII.Cancer-related genes were highly enriched with chromatin interactions,and chromatin interactions specific to the A549 cell line were associated with oncogenes and tumor suppressor genes,such as additional repressive interactions on FOXO4 and promoter–promoter interactions between NF1 and RNF135.Knockout of an anchor associated with chromatin interactions reversed the dysregulation of cancer-related genes,suggesting that chromatin interactions are essential for proper expression of lung cancer-related genes.These findings demonstrate the 3D landscape and gene regulatory relationships of the lung cancer genome.

Investigation on Normal Dynamic Contact Characteristics of Mechanical Interface of Machine Tools

The dynamic contact characteristics of mechanical interface significantly impact the performance of machine tools.The static contact behaviors of mechanical interface have been studied.However,most mechanical interfaces are exposed to dynamic load.It is necessary to study the dynamic contact characteristics of mechanical interface.A normal dynamic microcosmic contact model is built using the statistical method,and the interactional effects of adjacent asperities are considered.The influences of the normal preload,vibrational frequency and displacement amplitude on normal contact stiffness and damping of mechanical interface are revealed.The predicted contact stiffness and damping of mechanical interface are verified by a series of simulations and experiments.