Biology subjects

Dynan, W. S.

Publications and source records attributed to Dynan, W. S..

2 recordsLinked to original sources

bioRxiv2020

Characterization of exosome release and extracellular vesicle-associated miRNAs for human bronchial epithelial cells irradiated with high charge and energy ions

Exosomes are extracellular vesicles that mediate transport of nucleic acids, proteins, and other molecules. Prior work has implicated exosomes in the transmission of radiation nontargeted effects. Here we investigate the ability of energetic heavy ions, representative of species found in galactic cosmic rays, to stimulate exosome release from human bronchial epithelial cells in vitro. Immortalized human bronchial epithelial cells (HBEC3-KT F25F) were irradiated with 1.0 Gy of high linear energy transfer (LET) 48Ti, 28Si, or 16O ions, or with 10 Gy of low-LET reference {gamma}-rays, and extracellular vesicles were collected from conditioned media. Preparations were characterized by single particle tracking analysis, transmission electron microscopy, and immunoblotting for the exosomal marker, TSG101. Irradiation with high-LET ions, but not {gamma}-rays, stimulated exosome release by about 3-fold, relative to mock-irradiated controls. The exosome-enriched vesicle preparations contained pro-inflammatory damage-associated molecular patterns, including HSP70 and calreticulin. Additionally, miRNA profiling was performed for vesicular RNAs using NanoString technology. The miRNA profile was skewed toward a small number of species that have previously been shown to be involved in cancer initiation and progression, including miR-1246, miR-1290, miR-23a, and miR-205. Additionally, a set of 24 miRNAs was defined as modestly over-represented in preparations from HZE ion-irradiated versus other cells. Gene set enrichment analysis based on the over-represented miRNAs showed highly significant association with nonsmall cell lung and other cancers.

molecular biology↗

bioRxiv2019

Oncoprotein CoAA repeats interact with RNA polymerase II CTD repeats

The heptad repeating sequence of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II is highly conserved in eukaryotes. In yeast, a CTD code consisting of pairs of heptad repeats is essential for viability. However, the strict requirement of diheptad repeats for the CTD function in transcription and splicing is unexplained. Here we show that CoAA (gene symbol RBM14), an oncoprotein and mammalian transcriptional coactivator, possesses diheptad repeats and directly interacts with the CTD. CoAA comprises 27 copies of tyrosine-rich repeats and regulates pre-mRNA synthesis and alternative splicing. Tyrosine substitutions in either the CoAA repeats or the CTD repeats diminish their interactions. Ser2- or Ser5-phosphorylated CTD peptides exhibit higher binding affinity to CoAA than the corresponding non-phosphorylated CTD peptide. CoAA dynamically interacts with both the CTD and hnRNP M, which is an alternative splicing regulator also comprising diheptad repeats. Arginine methylation of CoAA switches its interaction from the hnRNP M repeats to the CTD repeats. This study provides a mechanism for CoAA at the interface of transcription and alternative splicing, and explains the functional requirement of diheptad repeats in the CTD. In the human genome, tyrosine-rich repeats similar to the CoAA repeats were only found in six oncoproteins including EWS and SYT. We suggest that the diheptad sequence is one of the signature features for the CTD interaction among oncoproteins involved in transcription and alternative splicing. We anticipate that direct RNA Pol II interaction is a mechanism in oncogenesis.

biochemistry↗